CN107600173A

CN107600173A - A kind of automobile hydraulic variable ratio steering and its Multipurpose Optimal Method

Info

Publication number: CN107600173A
Application number: CN201710852938.XA
Authority: CN
Inventors: ***; 赵万忠; 张子俊; 赵宏宇; 栾众楷; 王春燕
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2017-09-20
Filing date: 2017-09-20
Publication date: 2018-01-19
Anticipated expiration: 2037-09-20
Also published as: CN107600173B

Abstract

The invention discloses a kind of automobile hydraulic variable ratio steering and its Multipurpose Optimal Method, system includes machine driving module, hydraulic booster module, variable ratio module and main control module.For the steering, the mechanical configuration parameter and hydraulic parameter that selection has a great influence to steering behaviour are as optimized variable, optimization aim is steering response and steering energy consumption, under the constraints of steering sensitivity, multiple-objection optimization is carried out with the genetic algorithms of NSGA II of technology of sharing between the mixing microhabitat colony proposed.Hydraulic pressure variable ratio steering according to automobile running working condition, can adjust the size of steering gearratio, turned to when meeting low speed flexibly, high speed when stable direction characteristic.System core parameter in the case of can sailing stability ensureing row automobile, obtains preferable steering response after optimization, while reduces system capacity loss, obtains good synthesis steering behaviour.

Description

A kind of automobile hydraulic variable ratio steering and its Multipurpose Optimal Method

Technical field

The invention belongs to automobile steering system technical field, refer specifically to for a kind of automobile hydraulic variable ratio steering and Its Multipurpose Optimal Method.

Background technology

With the development of power steering system, motor turning performance is greatly improved.Automobile generally uses at present Hydraulic power-assist steering system and electric boosting steering system, export power by additionaling power source so that driver performs steering It is more light during operation.Hydraulic booster can provide larger torque, but assist torque can not accurately adjust and system energy consumption compared with Greatly；It is electric boosted to realize that assist characteristic changes with driving cycle, but due to electrical safety limit, there is provided power-assisted size It is restricted.Either hydraulic power-assisted steering or electric power steering, its steering gear ratio are all fixed unmodifiable.Become It is smaller that gearratio steering can be such that vehicle is driven when running at a low speed, turn to it is more flexible, improve vehicle flexibility and Driver is handling；When running at high speed, transmission is bigger, improves the stability and security of vehicle.

Research to steering variable ratio at present rarely has disclosure to the systematic research also in starting stage, the country Report.Foreign countries only have German BMW and Purely mechanical AFS active front formula steering, but the system are applied on limousine Using electric boosted mode, limited assist torque can only be provided, is difficult to apply in heavy goods vehicles.

Because hydraulic pressure variable ratio steering system structural is complicated, it is related to multiple subjects such as machinery, electronics, hydraulic pressure, simultaneously Also mutually there is influence in multiple Performance Evaluating Indexes, the Parameters Optimal Design of reasonable science plays key work to systematic function With.Therefore, accurate Optimized model is established, hydraulic pressure variable ratio steering key parameter is carried out using suitable optimized algorithm Optimization, is a particularly important job, the development to automobile power steering has impetus.

The content of the invention

Above-mentioned the deficiencies in the prior art are directed to, it is an object of the invention to provide a kind of steering of automobile hydraulic variable ratio System and its Multipurpose Optimal Method, to overcome problems of the prior art.The present invention makes to turn by variable ratio module Be driven to system in low speed it is smaller, be driven during high speed it is bigger, and by providing a kind of Multipurpose Optimal Method so that vapour In the case that car keeps riding stability, preferable steering response is obtained, while reduces system capacity loss, is obtained good comprehensive Close steering behaviour.

To reach above-mentioned purpose, the technical solution adopted by the present invention is as follows：

A kind of automobile hydraulic variable ratio steering of the present invention, including：Mechanical steering module, hydraulic booster module, Variable ratio module and main control module；

Described machine driving module includes steering wheel, rotary angle transmitter, torque sensor, steering spindle, circulating ball and turned to Device, pitman arm, steering drag link, steering trapezium and wheel；

Steering spindle upper end is connected with steering wheel, and lower end is connected with ball-and-nut steering gear input；

Ball-and-nut steering gear output end is connected with pitman arm；

Pitman arm is connected with the variable ratio module；

Steering drag link input connects the variable ratio module, output end connection steering trapezium and wheel, realizes car Take turns go to action；

Rotary angle transmitter connects on the steering wheel, inputs corner for obtaining driver, and pass to main control module；

Torque sensor is connected in steering spindle, for obtaining driver's input torque, and passes to main control module；

Described hydraulic booster module includes hydraulic booster motor, double acting liquid piece pump, rotary valve, power-assisted power cylinder；

Hydraulic booster motor output end is connected with double-action hydraulic pump intake；

The oil inlet connection fuel tank of double acting liquid piece pump, under the driving of hydraulic booster motor, by hydraulic oil from fuel-displaced oral instructions It is delivered to rotary valve；

The high pressure hydraulic fluid port and low pressure hydraulic fluid port of rotary valve pass through oil inlet pipe and the oil inlet and oil-out of ball-and-nut steering gear respectively Connection, its oil return opening are connected with the fuel tank；

Power-assisted power cylinder is made up of the part between the enclosure of the ball-and-nut steering gear and steering nut outside, The front-end and back-end of power-assisted power cylinder have a hydraulic fluid port, and fluid circulates between rotary valve during for carrying out hydraulic booster；

Described variable ratio module includes direct current generator, hydraulic pump, proportional direction valve, hydraulic cylinder, hydraulic cylinder piston；

Direct current generator output end is connected with hydraulic pump, and high pressure caused by hydraulic pump is transferred to the oil inlet of proportional direction valve；

Proportional direction valve uses 3-position 4-way form, changes operating position by the control signal of the main control module, And hydraulic oil is controlled to pass in and out the hydraulic cylinder nested with the steering drag link；

Hydraulic cylinder shell is fixedly connected with the pitman arm, hydraulic cylinder mounted inside single-rod piston；

The piston-rod end of hydraulic cylinder piston is connected with the steering drag link；

Described main control module senses with rotary angle transmitter, torque sensor, vehicle speed sensor, yaw velocity respectively Device is connected, the speed letter in steering wheel angle signal, dtc signal and vehicle traveling process for receiving driver's input Number and yaw rate signal, export three control signals by calculating, drive hydraulic booster motor, direct current generator and ratio respectively Proportional direction valve works.

A kind of Multipurpose Optimal Method of automobile hydraulic variable ratio steering of the present invention, comprises the following steps：

(1) automobile hydraulic variable ratio steering model, vehicle Three Degree Of Freedom model and tire model, wherein institute are established Stating automobile hydraulic variable ratio steering model includes steering wheel-steering shaft model, ball-and-nut steering gear model, hydraulic booster Modular model, variable ratio modular model；

(2) establish automobile hydraulic variable ratio steering Performance Evaluation System, with steering response, steering sensitivity and Steering energy consumption establishes corresponding performance function formula as Performance Evaluating Indexes；

(3) mechanical configuration parameter and hydraulic pressure to be had a great influence in automobile hydraulic variable ratio steering to steering behaviour Parameter is as optimized variable, using steering response and steering energy consumption as optimization aim, under the constraints of steering sensitivity, Establish automobile hydraulic variable ratio steering Model for Multi-Objective Optimization；

(4) automobile hydraulic variable ratio steering Model for Multi-Objective Optimization is based on, using common between mixing microhabitat colony The genetic algorithms of NSGA- II for enjoying technology carry out multiple-objection optimization, in the case where ensureing stability of automobile, obtain and preferably turn to Road feel, while reduce steering energy loss.

Preferably, steering wheel-steering shaft model in the step (1) is：

In formula：J_sFor steering wheel rotation inertia, B_sFor steering spindle viscous damping coefficient, θ_sFor steering wheel angle, T_SFor torque The torque value that sensor measures, T_dFor steering wheel input torque, k_sFor steering spindle rigidity, θ_lgFor steering screw corner；

Ball-and-nut steering gear model is：

In formula：J_lgFor the equivalent moment of inertia of steering screw, B_lgFor the equivalent viscous damping ratio of steering screw, F is to turn To the axial service load of screw rod, l is the centre-to-centre spacing of screw rod power, m_lmFor the quality of steering nut, x is the displacement of steering nut, B_lmFor the viscosity resistance coefficient of steering nut, F_lmFor nut axial force, T_csTorque, r are fanned for tooth_wPitch radius, B are fanned for tooth_csFor tooth The viscous damping coefficient of fan, θ_csCorner, T are fanned for tooth_pThe equivalent moment for being steering resisting moment on rocker arm shaft, J_csFor turning for tooth fan Dynamic inertia, F_EHPSThe power-assisted provided by hydraulic booster module, A_pFor the effective area of hydraulic cylinder piston, P_A、P_BRespectively hydraulic pressure Cylinder pressure at two ends；

Hydraulic booster modular model is：

In formula：θ_m1For the corner of hydraulic booster motor, J_m1For hydraulic booster motor and the Equivalent Rotational of double-acting vane pump Inertia, B_m1For hydraulic booster motor and the equivalent viscous damping coefficient of double-acting vane pump, T_m1For helping for hydraulic booster motor output Power torque, T_pump1For double-acting vane pump work torque, L_A1For hydraulic booster armature inductance coefficent, U_A1For hydraulic booster Armature voltage, I_A1For hydraulic booster armature electric current, R_A1For hydraulic booster armature resistance, K_T1For hydraulic booster The voltage induced coefficient of motor, ω₁For the angular speed of hydraulic booster motor, q is double-acting vane pump discharge capacity, and B is stator thickness, R₂For stator major axis radius, R₁For stator minor axis radius, Z is vane pump blade number, and t is vane thickness, P_sFor output oil pressure, C_q For discharge coefficient, A_iWith Δ P_iFor the orifice size and pressure differential of i-th of valve port, x_rFor valve port opening, Q_sFor the flow of valve port；

Variable ratio modular model is：

In formula：m_zFor piston and piston rod equivalent mass, B_zFor piston and piston rod Equivalent damping coefficient, x_zFor hydraulic cylinder Piston displacement, x_pFor relative displacement, F_zFor the steering drag suffered by hydraulic cylinder piston, F_bcdFor thrust hydraulic cylinder size, A_pLFor liquid Pressure cylinder piston effective area, P_LPoor, the J for hydraulic cylinder pressure at two ends_m2For DC motor rotor rotary inertia, θ_m2Turn for direct current generator Angle, B_m2For direct current generator viscous damping coefficient, T_LFor direct current generator load torque, T_em2For direct current generator electromagnetic torque, F_TTTo turn Power, r are transmitted to rocking arm_yFor pitman arm length, T_csTorque is fanned for tooth；

Vehicle Three Degree Of Freedom model and tire model are respectively：

In formula：U is longitudinal velocity, and m is complete vehicle quality, I_zRotary inertia for car mass to z-axis, I_xFor sprung mass To the rotary inertia of x-axis, ω_rFor yaw velocity, β is side slip angle, and φ is vehicle roll angle, and α is front-wheel side drift angle, δ For front wheel steering angle, I_xzIt is sprung mass to x, the product of inertia of z-axis, d is wheelspan, G_PFor screw rod to front wheel drive ratio, h is suspension Barycenter is to the distance of roll axis, N_βFor caused by unit side slip angle to the torque of z-axis, N_rProduced for unit yaw velocity The raw torque to z-axis, N_φFor caused by unit roll velocity to the torque of z-axis, N_δFor caused by unit front wheel angle to z The torque of axle, L_pFor caused by unit roll velocity to the moment of face of x-axis, L_φOutside caused by unit angle of heel to x-axis Torque, Y_rFor ground cornering force, Y caused by unit yaw velocity_βIt is lateral for ground caused by unit vehicle side drift angle Reaction force, Y_φFor ground cornering force, Y caused by unit angle of heel_δIt is lateral for ground caused by unit front wheel angle Reaction force, k₁For front-wheel cornering stiffness, E₁For the radian factor.

Preferably, the Performance Evaluation System established in the step (2) includes steering response, steering sensitivity and steering Three Performance Evaluating Indexes of system energy consumption, the steering response performance function formula are：

In formula：

Z₁=qk_TT+lA_pk_ak₁k_s+lA_pk_ak₂k_s；

The performance function formula of the steering sensitivity is：

In formula：

A₂=muL_pN_δ+I_xN_δY_β-I_xN_βY_δ

A₁=muL_φN_δ-L_pN_δY_β+L_pN_βY_δ-hum_sN_φY_δ+hum_sN_δY_φ

A₀=-L_φN_δY_β+L_φN_βY_δ

B₁=-muL_φN_r+muL_pN_β-L_pN_βY_r+hum_sN_φY_r-I_zL_φY_β+L_pN_rY_β-I_xzN_φY_β

-hum_sN_rY_φ+I_xzN_βY_φ

B₀=muL_φN_β-L_φN_βY_r+L_φN_rY_β-hum_sN_φY_β+hum_sN_βY_φ

F₁=-muL_pN_δ+L_pN_δY_r+I_zL_φY_δ-L_pN_rY_δ+I_xzN_φY_δ-I_xzN_δY_φ

F₀=-muL_φN_δ+L_φN_δY_r-L_φN_rY_δ+hum_sN_φY_δ-hum_sN_δY_φ

H₂=-muI_xzN_δ-huI_zm_sY_δ

H₁=-hum_sN_δY_r+I_xzN_δY_β+hum_sN_rY_δ-I_xzN_βY_δ

H₀=hum_sN_δY_β-hum_sN_βY_δ

Q₆=B₄X₂

Q₅=B₄Y₂+B₃X₂

Q₄=B₄Z₂+B₃Y₂+B₂X₂

The performance function formula of the steering energy consumption is：

E=P_ECU-loss+2P_motor-loss+2P_pump-loss+2P_v-loss

In formula：

Represent controller energy consumption；

P_motor-loss=M_c+C_Frω+C_Fr2ω²+ C, represent energy consumption of electrical machinery；

P_pump-loss=P_pump-in-P_pump-out, represent hydraulic pump energy consumption；

Represent hydraulic valve energy consumption；

In formula：R_AFor armature resistance, I_AFor armature supply, U_sFor controller both end voltage, R_elecFor controller resistance, M_cFor Torque loss caused by being rubbed in motor, C_FrIt is speed than coefficient of friction, ω is motor speed, C_Fr2For fast ratio square coefficient of friction, C is motor unknown losses.

Preferably, in the step (3), mechanical configuration parameter and liquid that optimized variable selection has a great influence to steering behaviour Parameter is pressed to make, including：The rotary inertia J of hydraulic booster motor_m1, direct current generator rotary inertia J_m2, torque sensor rigidity k_s、 Double-acting vane pump stator thickness B, double-acting vane pump major axis radius R₂, tooth fan pitch radius r_w；

Object function is：

In formula：k'₁、k'₂For weight coefficient；

Represent steering response；

f(x₂)=P_ECU-loss+2P_motor-loss+2P_pump-loss+2P_v-loss, represent system energy consumption；

Constraints is：

Take ω₀=45Hz so that functionMeet 0.0011≤f (x₃)≤0.0081, Ensure that steering sensitivity is in zone of reasonableness.

Preferably, between the mixing microhabitat colony in the step (4) technology of sharing the genetic algorithms of NSGA- II, specifically Step is as follows：

Step 4.1：Using binary coding method to chromosome coding, the solution space of problem is converted into and meets heredity The search space of algorithm process requirement, initiation parameter；

Step 4.2：Randomly generate new population Q_t, at the t=0 moment, N number of feasible solution Y is randomly generated, brings feasible solution into institute Object function f (x) is stated, calculates the local congestion distance L [k] between individual adaptation degree F' and individual corresponding with target function value D=L [k] d+L [k+1] m-L [k+1] m, according to obtained individual adaptation degree, by population Q_tIt is divided into several sub-group P_K, k=1,2, 3......；

Step 4.3：Each sub-group independently evolve and perform selection, intersect and mutation operation, so as to get solution be uniformly distributed, Obtain population Q of new generation_t+1；The local congestion distance obtained using the algorithms of NSGA- II is to Q_t+1Individual carry out it is quick non-dominant Sequence, obtained result and parent Q_tMerge, then keep strategy to select individual composition new population Q' with elite_t+1, Optimization is set to be carried out towards direction optimal Pareto；

Step 4.4：By new population Q'_t+1Initial population as niche algorithm, it is assumed that individual i ∈ S, S are shared group Body, j ∈ O, O are other colonies, and Max size are total group number；According toI= 1,2 ..., Max size*15%, calculate colony and share fitness S, according to the average fitness of each sub-group, select average The best sub-group of fitness shares colony as microhabitat；

Step 4.5：Defect individual is selected in Max size*15% ratios to each sub-group, calculates between colony excellent The Hamming distances of body

Step 4.6：Based on shared mechanism between microhabitat colony, the similarity between defect individual is judged according to Hamming distances, The fitness of the shared sub-group of adjustment isThe fitness of other sub-groups is

Step 4.7：By the adjusted sub-group of fitness, using the elite plan of the quick non-dominated ranking of the algorithms of NSGA- II Slightly, the poor sub-group of performance is eliminated, reselects and produces new sub-group P'_K, k=1,2,3......, and form new population Q”_t+1；

Step 4.8：Population is evaluated, if number of iterations reaches defined maximum or meets the condition of convergence, terminated Optimize, otherwise circulation step 4.4 to step 4.7；

Step 4.9：Chromosome is decoded, and disaggregation is sorted to obtain optimal pareto disaggregation.

Beneficial effects of the present invention：

Automobile hydraulic variable ratio steering proposed by the present invention, it can change and turn to according to automobile difference driving cycle Drive system compares size.When automobile is run at a low speed, variable ratio module provides a superposition displacement so that transmission is smaller, carries High vehicle flexibility and driver are handling；For automobile when running at high speed, variable ratio module provides opposite direction displacement so that passes It is dynamic bigger, improve the stability and security of vehicle.The system can preferably manipulate sense to driver and drive road feel, together Shi Jiaqiang Automobile operation stability, reduces accident.

The Multipurpose Optimal Method of automobile hydraulic variable ratio steering proposed by the present invention, be suitable for comprising machinery, Multiple subjects such as electronics, hydraulic pressure are, it is necessary to consider the complication system of the multiple Performance Evaluating Indexes of steering simultaneously.Pass through this method Optimization to steering key parameter, automobile can make it that in the case where ensureing riding stability, obtain and preferably turn to Road feel, simultaneity factor energy consumption effectively reduce, and obtain good synthesis steering behaviour.

The genetic algorithms of NSGA- II of technology of sharing between mixing microhabitat colony proposed by the present invention, effectively by between colony Shared mechanism and introducing elitism strategy, can make full use of the restriction and contact between each population of nature, keep colony It is multifarious simultaneously, retain excellent colony as far as possible.Compared to common genetic algorithm, technology of sharing between mixing microhabitat colony The genetic algorithms of NSGA- II can improve population quality, effectively avoid population precocious, while the search capability and convergence rate of algorithm Increase.

Brief description of the drawings

Fig. 1 is the theory structure block diagram of automobile hydraulic variable ratio steering of the present invention；

Fig. 2 is the flow chart of optimization method of the present invention；

Fig. 3 is optimized algorithm flow chart；

In figure, 1- steering wheels, 2- rotary angle transmitters, 3- torque sensors, 4- steering spindles/steering screw, 5- teeth fan, 6- enters Oil pipe, 7- rotary valves, 8- check valves, 9- double-acting vane pumps, 10- hydraulic booster motors, 11- oil return pipes, 12- fuel tanks, 13- are turned to Drag link, 14- steering trapeziums, 15- wheels, 16- direct current generators, 17 hydraulic pumps, 18- proportional direction valves, 19- hydraulic cylinders, 20- liquid Pressure cylinder piston, 21- pitman arms, 22- steering nuts, 23- main control modules, 24- power-assisted power cylinders, 25- ball-and-nut steering gears, A- angular signals, b- dtc signals, c- GESs, d- yaw rate signals, e- hydraulic booster motor control signals, f- are straight Flow motor control signal, g- proportion directional valve control signals.

Embodiment

For the ease of the understanding of those skilled in the art, the present invention is made further with reference to embodiment and accompanying drawing Bright, the content that embodiment refers to not is limitation of the invention.

Shown in reference picture 1, a kind of automobile hydraulic variable ratio steering of the invention, including：Mechanical steering module, liquid Press power-assisted module, variable ratio module and main control module (ECU) 23；

Described machine driving module includes steering wheel 1, rotary angle transmitter 2, torque sensor 3, steering spindle 4, circulating ball Steering gear 25, pitman arm 21, steering drag link 13, steering trapezium 14 and wheel 15；

The upper end of steering spindle 4 is connected with steering wheel 1, and lower end is connected with ball-and-nut steering gear input；

Ball-and-nut steering gear output end is connected by tooth fan 5 with pitman arm 21；

Pitman arm 21 is connected with the variable ratio module；

The input of steering drag link 13 connects the variable ratio module, output end connection steering trapezium 14 and wheel 15, Realize the go to action of wheel 15；

Rotary angle transmitter 2 is connected on steering wheel 1, inputs corner for obtaining driver, and pass to main control module 23；

Torque sensor 3 is connected in steering spindle 4, for obtaining driver's input torque, and passes to main control module 23；

Described hydraulic booster module includes hydraulic booster motor 10, double acting liquid piece pump 9, rotary valve 7, power-assisted power cylinder 24；

The output end of hydraulic booster motor 10 is connected with the entrance of double-action hydraulic pump 9；

The oil inlet connection fuel tank 12 of double acting liquid piece pump 9, under the driving of hydraulic booster motor 10, hydraulic oil is by unidirectional Valve 8 is delivered to rotary valve 7 from oil-out；

The high pressure hydraulic fluid port and low pressure hydraulic fluid port of rotary valve 7 by the oil inlet of oil inlet pipe 6 and ball-and-nut steering gear 25 and go out respectively Hydraulic fluid port is connected, and its oil return opening is connected with the fuel tank 12；

Power-assisted power cylinder 24 is by the portion between the enclosure of the ball-and-nut steering gear 25 and the outside of steering nut 22 Be grouped into, the front-end and back-end of power-assisted power cylinder have a hydraulic fluid port, during for carrying out hydraulic booster between rotary valve 7 oil Liquid stream is led to；

Described variable ratio module includes direct current generator 16, hydraulic pump 17, proportional direction valve 18, hydraulic cylinder 19, hydraulic pressure Cylinder piston 20；

The output end of direct current generator 16 is connected with hydraulic pump 17, and high pressure caused by hydraulic pump 17 is transferred to proportional direction valve 18 Oil inlet；

Proportional direction valve 18 uses 3-position 4-way form, changes working position by the control signal of the main control module Put, and control hydraulic oil to pass in and out the hydraulic cylinder 19 nested with the steering drag link 13；Adoption rate direction valve, can same time control The direction of running of hydraulic power oil processed and uninterrupted.It is simultaneously emitted by by main control module to direct current generator and proportional direction valve two Signal, the flow of influent cylinder pressure can be made to obtain more precise control.

The shell of hydraulic cylinder 19 is fixedly connected with the pitman arm 21, hydraulic cylinder mounted inside single-rod piston；

The piston-rod end of hydraulic cylinder piston 20 is connected with the steering drag link 13；

Described main control module senses with rotary angle transmitter, torque sensor, vehicle speed sensor, yaw velocity respectively Device is connected, the speed in steering wheel angle signal a, dtc signal b and vehicle traveling process for receiving driver's input Signal c and yaw rate signal d, three control signals are exported by calculating, drive hydraulic booster motor 10, direct current respectively Machine 16 and proportional direction valve 18 work.

During work, main control module receives speed, yaw rate signal, is passed by optimal steering is calculated Dynamic ratio, while the corner and dtc signal of driver's input are contrasted, obtain actual transmission and compare size.According to optimal gearratio and reality The difference of border gearratio is main control module output hydraulic pressure assist motor control signal e regulations ball-and-nut steering gear power-assisted size, straight Flow motor control signal f regulation variable ratio modules hydraulic flow, proportion directional valve control signal g regulation proportional direction valve work Position.Wherein, when actual transmission ratio is more than optimal gearratio, proportional direction valve is in the work of right position, and hydraulic cylinder right chamber enters height Force feed, left chamber go out low pressure oil, and hydraulic cylinder piston opposing hydraulic cylinder inversely moves, and reduce steering output gearratio；Work as reality When border gearratio is less than optimal gearratio, proportional direction valve is in the work of left position, and hydraulic cylinder left chamber enters hydraulic oil, right chamber goes out low pressure Oil, hydraulic cylinder can match the positive movement of opposing hydraulic cylinder, increase steering gearratio；The work of variable ratio module is not needed When, proportional direction valve is in intermediate position, and hydraulic oil directly returns to fuel tank through oil return opening, and hydraulic pump is in unloading condition, Reduce energy expenditure.

Steering wheel-steering shaft model is：

Ball-and-nut steering gear model is：

In formula：J_lgFor the equivalent moment of inertia of steering screw, B_lgFor the equivalent viscous damping ratio of steering screw, F is to turn To the axial service load of screw rod, l is the centre-to-centre spacing of screw rod power, m_lmFor the quality of steering nut, x is the displacement of steering nut, B_lmFor the viscosity resistance coefficient of steering nut, F' is nut axial force, T_csTorque, r are fanned for tooth_wPitch radius, B are fanned for tooth_csFor tooth The viscous damping coefficient of fan, θ_csCorner, T are fanned for tooth_pThe equivalent moment for being steering resisting moment on rocker arm shaft, J_csFor turning for tooth fan Dynamic inertia, F_EHPSThe power-assisted provided by hydraulic booster module, A_pFor the effective area of hydraulic cylinder piston, P_A、P_BRespectively hydraulic pressure Cylinder pressure at two ends；

Hydraulic booster modular model is：

Variable ratio modular model is：

Vehicle Three Degree Of Freedom model and tire model are respectively：

The steering response performance function formula of foundation is：

In formula：

Z₁=qk_TT+lA_pk_ak₁k_s+lA_pk_ak₂k_s；

The performance function formula of the steering sensitivity of foundation is：

In formula：

A₂=muL_pN_δ+I_xN_δY_β-I_xN_βY_δ

A₁=muL_φN_δ-L_pN_δY_β+L_pN_βY_δ-hum_sN_φY_δ+hum_sN_δY_φ

A₀=-L_φN_δY_β+L_φN_βY_δ

B₁=-muL_φN_r+muL_pN_β-L_pN_βY_r+hum_sN_φY_r-I_zL_φY_β+L_pN_rY_β-I_xzN_φY_β-hum_sN_rY_φ+I_xzN_βY_φ

B₀=muL_φN_β-L_φN_βY_r+L_φN_rY_β-hum_sN_φY_β+hum_sN_βY_φ

F₁=-muL_pN_δ+L_pN_δY_r+I_zL_φY_δ-L_pN_rY_δ+I_xzN_φY_δ-I_xzN_δY_φ

F₀=-muL_φN_δ+L_φN_δY_r-L_φN_rY_δ+hum_sN_φY_δ-hum_sN_δY_φ

H₂=-muI_xzN_δ-huI_zm_sY_δ

H₁=-hum_sN_δY_r+I_xzN_δY_β+hum_sN_rY_δ-I_xzN_βY_δ

H₀=hum_sN_δY_β-hum_sN_βY_δ

Q₆=B₄X₂

Q₅=B₄Y₂+B₃X₂

Q₄=B₄Z₂+B₃Y₂+B₂X₂

The performance function formula of the steering energy consumption of foundation is：

E=P_ECU-loss+2P_motor-loss+2P_pump-loss+2P_v-loss

In formula：

Represent controller energy consumption；

Represent hydraulic valve energy consumption；

Wherein：R_AFor armature resistance；I_AFor armature supply, U_sFor controller both end voltage, R_elecFor controller resistance, M_cFor Torque loss caused by being rubbed in motor, C_FrIt is speed than coefficient of friction, ω is motor speed, C_Fr2For fast ratio square coefficient of friction, C is motor unknown losses.

The mechanical configuration parameter and hydraulic parameter that optimized variable selection has a great influence to steering behaviour are made, including：Hydraulic pressure helps The rotary inertia J of force motor_m1, direct current generator rotary inertia J_m2, torque sensor rigidity k_s, double-acting vane pump stator thickness B, double-acting vane pump major axis radius R₂, tooth fan pitch radius r_w；

During in order that driver obtaining certain steering response, steering energy expenditure is as small as possible, using information of road surface Effective frequency range (0, ω₀) in frequency domain energy average value represent the size of steering response, object function is：

In formula：k'₁、k'₂For weight coefficient；

Represent steering response；

Constraints is：

Take the average value ω of road surface effective information frequency₀=45Hz so that functionIt is full 0.0011≤f of foot (x₃)≤0.0081, ensure that steering sensitivity is in zone of reasonableness, automobile keeps stable transport condition.

Shown in reference picture 3, a kind of Multipurpose Optimal Method of automobile hydraulic variable ratio steering of the invention, propose NSGA- II genetic algorithms of technology of sharing, are comprised the following steps that between mixing microhabitat colony：

Concrete application approach of the present invention is a lot, and described above is only the preferred embodiment of the present invention, it is noted that for For those skilled in the art, under the premise without departing from the principles of the invention, some improvement can also be made, this A little improve also should be regarded as protection scope of the present invention.

Claims

A kind of 1. automobile hydraulic variable ratio steering, it is characterised in that including：Machine driving module, hydraulic booster module, Variable ratio module and main control module；

Described machine driving module include steering wheel, rotary angle transmitter, torque sensor, steering spindle, ball-and-nut steering gear, turn To rocking arm, steering drag link, steering trapezium and wheel；

Steering spindle upper end is connected with steering wheel, and lower end is connected with ball-and-nut steering gear input；

Ball-and-nut steering gear output end is connected with pitman arm；

Pitman arm is connected with the variable ratio module；

Steering drag link input connects the variable ratio module, output end connection steering trapezium and wheel, realizes that wheel turns To action；

Rotary angle transmitter connects on the steering wheel, inputs corner for obtaining driver, and pass to main control module；

Torque sensor is connected in steering spindle, for obtaining driver's input torque, and passes to main control module；

Described hydraulic booster module includes hydraulic booster motor, double acting liquid piece pump, rotary valve, power-assisted power cylinder；

Hydraulic booster motor output end is connected with double-action hydraulic pump intake；

Double acting liquid piece pump oil inlet connects fuel tank, under the driving of hydraulic booster motor, hydraulic oil is delivered to from oil-out and turned Valve；

The high pressure hydraulic fluid port and low pressure hydraulic fluid port of rotary valve are connected by oil inlet pipe with ball-and-nut steering gear oil inlet and oil-out respectively, its Oil return opening is connected with the fuel tank；

Power-assisted power cylinder is made up of the part between the enclosure of the ball-and-nut steering gear and steering nut outside, power-assisted The front-end and back-end of power cylinder have a hydraulic fluid port, and fluid circulates between rotary valve during for carrying out hydraulic booster；

Described variable ratio module includes direct current generator, hydraulic pump, proportional direction valve, hydraulic cylinder, hydraulic cylinder piston；

Direct current generator output end is connected with hydraulic pump, and high pressure caused by hydraulic pump is transferred to the oil inlet of proportional direction valve；

Proportional direction valve uses 3-position 4-way form, changes operating position by the control signal of the main control module, and control Hydraulic oil processed passes in and out the hydraulic cylinder nested with the steering drag link；

Hydraulic cylinder shell is fixedly connected with the pitman arm, hydraulic cylinder mounted inside single-rod piston；

The piston-rod end of hydraulic cylinder piston is connected with the steering drag link；

Described main control module respectively with rotary angle transmitter, torque sensor, vehicle speed sensor, yaw-rate sensor phase Even, for receive GES in the steering wheel angle signal of driver's input, dtc signal and vehicle traveling process and Yaw rate signal, three control signals are exported by calculating, drive hydraulic booster motor, direct current generator and ratio side respectively Worked to valve.
2. a kind of Multipurpose Optimal Method of automobile hydraulic variable ratio steering, it is characterised in that comprise the following steps：

(1) automobile hydraulic variable ratio steering model, vehicle Three Degree Of Freedom model and tire model are established, wherein, it is described Automobile hydraulic variable ratio steering model includes steering wheel-steering shaft model, ball-and-nut steering gear model, hydraulic booster mould Block models, variable ratio modular model；

(2) automobile hydraulic variable ratio steering Performance Evaluation System is established, with steering response, steering sensitivity and steering System energy consumption establishes corresponding performance function formula as Performance Evaluating Indexes；

(3) mechanical configuration parameter and hydraulic parameter to be had a great influence in automobile hydraulic variable ratio steering to steering behaviour As optimized variable, using steering response and steering energy consumption as optimization aim, under the constraints of steering sensitivity, establish Automobile hydraulic variable ratio steering Model for Multi-Objective Optimization；

(4) automobile hydraulic variable ratio steering Model for Multi-Objective Optimization is based on, shares skill using between mixing microhabitat colony The genetic algorithms of NSGA- II of art carry out multiple-objection optimization, in the case where ensureing stability of automobile, obtain and preferably turn to road Sense, while reduce steering energy loss.
3. the Multipurpose Optimal Method of automobile hydraulic variable ratio steering according to claim 2, it is characterised in that Steering wheel-steering shaft model in the step (1) is：

<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <msub> <mi>J</mi> <mi>s</mi> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mi>s</mi> </msub> <mo>+</mo> <msub> <mi>B</mi> <mi>s</mi> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;</mo> </mover> <mi>s</mi> </msub> <mo>=</mo> <msub> <mi>T</mi> <mi>d</mi> </msub> <mo>-</mo> <msub> <mi>T</mi> <mi>s</mi> </msub> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>=</mo> <msub> <mi>k</mi> <mi>s</mi> </msub> <mrow> <mo>(</mo> <msub> <mi>&theta;</mi> <mi>s</mi> </msub> <mo>-</mo> <msub> <mi>&theta;</mi> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> </mtable> </mfenced>

In formula：J_sFor steering wheel rotation inertia, B_sFor steering spindle viscous damping coefficient, θ_sFor steering wheel angle, T_SFor torque sensing The torque value that device measures, T_dFor steering wheel input torque, k_sFor steering spindle rigidity, θ_lgFor steering screw corner；

Ball-and-nut steering gear model is：

<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <msub> <mi>J</mi> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mo>+</mo> <msub> <mi>B</mi> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;</mo> </mover> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>T</mi> <mi>s</mi> </msub> <mo>-</mo> <mi>F</mi> <mo>&CenterDot;</mo> <mi>l</mi> </mtd> </mtr> <mtr> <mtd> <msub> <mi>m</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> <mover> <mi>x</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mo>+</mo> <msub> <mi>B</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> <mover> <mi>x</mi> <mo>&CenterDot;</mo> </mover> <mo>=</mo> <msub> <mi>F</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>T</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <mo>/</mo> <msub> <mi>r</mi> <mi>w</mi> </msub> <mo>+</mo> <msub> <mi>F</mi> <mrow> <mi>E</mi> <mi>H</mi> <mi>P</mi> <mi>S</mi> </mrow> </msub> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>J</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mi>s</mi> </msub> <mo>+</mo> <msub> <mi>B</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;</mo> </mover> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>T</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>T</mi> <mi>p</mi> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>F</mi> <mrow> <mi>E</mi> <mi>H</mi> <mi>P</mi> <mi>S</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>A</mi> <mi>p</mi> </msub> <mrow> <mo>(</mo> <msub> <mi>P</mi> <mi>A</mi> </msub> <mo>-</mo> <msub> <mi>P</mi> <mi>B</mi> </msub> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> </mtable> </mfenced>

In formula：J_lgFor the equivalent moment of inertia of steering screw, B_lgFor the equivalent viscous damping ratio of steering screw, F is steering spiral shell The axial service load of bar, l be screw rod power centre-to-centre spacing, m_lmFor the quality of steering nut, x is the displacement of steering nut, B_lmFor The viscosity resistance coefficient of steering nut, F_lmFor nut axial force, T_csTorque, r are fanned for tooth_wPitch radius, B are fanned for tooth_csFor tooth fan Viscous damping coefficient, θ_csCorner, T are fanned for tooth_pThe equivalent moment for being steering resisting moment on rocker arm shaft, J_csRotation for tooth fan is used to Amount, F_EHPSThe power-assisted provided by hydraulic booster module, A_pFor the effective area of hydraulic cylinder piston, P_A、P_BRespectively hydraulic cylinder two End pressure；

Hydraulic booster modular model is：

<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <mrow> <msub> <mi>J</mi> <mrow> <mi>m</mi> <mn>1</mn> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>B</mi> <mrow> <mi>m</mi> <mn>1</mn> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;</mo> </mover> <mrow> <mi>m</mi> <mn>1</mn> </mrow> </msub> <mo>=</mo> <msub> <mi>T</mi> <mrow> <mi>m</mi> <mn>1</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>T</mi> <mrow> <mi>p</mi> <mi>u</mi> <mi>m</mi> <mi>p</mi> <mn>1</mn> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>U</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <mo>=</mo> <msub> <mi>U</mi> <mrow> <mi>S</mi> <mn>1</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>I</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <msub> <mi>R</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>U</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <mo>=</mo> <mi>L</mi> <msub> <mover> <mi>I</mi> <mo>&CenterDot;</mo> </mover> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mi>R</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <msub> <mi>I</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <mo>+</mo> <msub> <mi>K</mi> <mrow> <mi>T</mi> <mn>1</mn> </mrow> </msub> <msub> <mi>&omega;</mi> <mn>1</mn> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>I</mi> <mrow> <mi>A</mi> <mn>1</mn> </mrow> </msub> <mo>=</mo> <msub> <mi>KT</mi> <mi>s</mi> </msub> <mo>=</mo> <msub> <mi>KK</mi> <mi>s</mi> </msub> <mrow> <mo>(</mo> <msub> <mi>&theta;</mi> <mi>s</mi> </msub> <mo>-</mo> <msub> <mi>&theta;</mi> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <mo>)</mo> </mrow> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mi>q</mi> <mo>=</mo> <mn>2</mn> <mi>B</mi> <mo>&lsqb;</mo> <mi>&pi;</mi> <mrow> <mo>(</mo> <msup> <msub> <mi>R</mi> <mn>2</mn> </msub> <mn>2</mn> </msup> <mo>-</mo> <msup> <msub> <mi>R</mi> <mn>1</mn> </msub> <mn>2</mn> </msup> <mo>)</mo> </mrow> <mo>-</mo> <mrow> <mo>(</mo> <msub> <mi>R</mi> <mn>2</mn> </msub> <mo>-</mo> <msub> <mi>R</mi> <mn>1</mn> </msub> <mo>)</mo> </mrow> <mi>Z</mi> <mi>t</mi> <mo>&rsqb;</mo> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>P</mi> <mi>S</mi> </msub> <mo>=</mo> <mfrac> <mi>&rho;</mi> <mrow> <mn>8</mn> <msup> <mrow> <mo>(</mo> <msub> <mi>C</mi> <mi>q</mi> </msub> <msub> <mi>A</mi> <mn>1</mn> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </mfrac> <msup> <mrow> <mo>(</mo> <msub> <mi>Q</mi> <mi>S</mi> </msub> <mo>+</mo> <msub> <mi>A</mi> <mi>P</mi> </msub> <mfrac> <mrow> <msub> <mi>dx</mi> <mi>r</mi> </msub> </mrow> <mrow> <mi>d</mi> <mi>t</mi> </mrow> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> <mo>+</mo> <mfrac> <mi>&rho;</mi> <mrow> <mn>8</mn> <msup> <mrow> <mo>(</mo> <msub> <mi>C</mi> <mi>q</mi> </msub> <msub> <mi>A</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </mfrac> <msup> <mrow> <mo>(</mo> <msub> <mi>Q</mi> <mi>S</mi> </msub> <mo>-</mo> <msub> <mi>A</mi> <mi>P</mi> </msub> <mfrac> <mrow> <msub> <mi>dx</mi> <mi>r</mi> </msub> </mrow> <mrow> <mi>d</mi> <mi>t</mi> </mrow> </mfrac> <mo>)</mo> </mrow> <mn>2</mn> </msup> </mrow> </mtd> </mtr> </mtable> </mfenced>

In formula：θ_m1For the corner of hydraulic booster motor, J_m1For hydraulic booster motor and the equivalent moment of inertia of double-acting vane pump, B_m1For hydraulic booster motor and the equivalent viscous damping coefficient of double-acting vane pump, T_m1Power-assisted for the output of hydraulic booster motor turns Square, T_pump1For double-acting vane pump work torque, L_A1For hydraulic booster armature inductance coefficent, U_A1For hydraulic booster motor Armature voltage, I_A1For hydraulic booster armature electric current, R_A1For hydraulic booster armature resistance, K_T1For hydraulic booster motor Voltage induced coefficient, ω₁For the angular speed of hydraulic booster motor, q is double-acting vane pump discharge capacity, and B is stator thickness, R₂For Stator major axis radius, R₁For stator minor axis radius, Z is vane pump blade number, and t is vane thickness, P_sFor output oil pressure, C_qFor stream Coefficient of discharge, A_iWith Δ P_iFor the orifice size and pressure differential of i-th of valve port, x_rFor valve port opening, Q_sFor the flow of valve port；

Variable ratio modular model is：

<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <mrow> <msub> <mi>m</mi> <mi>z</mi> </msub> <mrow> <mo>(</mo> <msub> <mover> <mi>x</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mi>z</mi> </msub> <mo>+</mo> <msub> <mover> <mi>x</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mi>p</mi> </msub> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>B</mi> <mi>z</mi> </msub> <msub> <mover> <mi>x</mi> <mo>&CenterDot;</mo> </mover> <mi>z</mi> </msub> <mo>=</mo> <msub> <mi>F</mi> <mrow> <mi>T</mi> <mi>T</mi> </mrow> </msub> <mo>+</mo> <msub> <mi>F</mi> <mrow> <mi>b</mi> <mi>c</mi> <mi>d</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>F</mi> <mi>z</mi> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>F</mi> <mrow> <mi>b</mi> <mi>c</mi> <mi>d</mi> </mrow> </msub> <mo>=</mo> <msub> <mi>A</mi> <mrow> <mi>p</mi> <mi>L</mi> </mrow> </msub> <msub> <mi>P</mi> <mi>L</mi> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>J</mi> <mrow> <mi>m</mi> <mn>2</mn> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mrow> <mi>m</mi> <mn>2</mn> </mrow> </msub> <mo>+</mo> <msub> <mi>B</mi> <mrow> <mi>m</mi> <mn>2</mn> </mrow> </msub> <msub> <mover> <mi>&theta;</mi> <mo>&CenterDot;</mo> </mover> <mrow> <mi>m</mi> <mn>2</mn> </mrow> </msub> <mo>=</mo> <msub> <mi>T</mi> <mrow> <mi>e</mi> <mi>m</mi> <mn>2</mn> </mrow> </msub> <mo>-</mo> <msub> <mi>T</mi> <mi>L</mi> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <msub> <mi>F</mi> <mrow> <mi>T</mi> <mi>T</mi> </mrow> </msub> <mo>=</mo> <mfrac> <msub> <mi>T</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <msub> <mi>r</mi> <mi>y</mi> </msub> </mfrac> </mrow> </mtd> </mtr> </mtable> </mfenced>

In formula：m_zFor piston and piston rod equivalent mass, B_zFor piston and piston rod Equivalent damping coefficient, x_zFor hydraulic cylinder piston Displacement, x_pFor relative displacement, F_zFor the steering drag suffered by hydraulic cylinder piston, F_bcdFor thrust hydraulic cylinder size, A_pLFor hydraulic cylinder Piston effective area, P_LPoor, the J for hydraulic cylinder pressure at two ends_m2For DC motor rotor rotary inertia, θ_m2For direct current generator corner, B_m2For direct current generator viscous damping coefficient, T_LFor direct current generator load torque, T_em2For direct current generator electromagnetic torque, F_TTTo turn to Rocking arm transmits power, r_yFor pitman arm length, T_csTorque is fanned for tooth；

Vehicle Three Degree Of Freedom model and tire model are respectively：

<mfenced open = "{" close = ""> <mtable> <mtr> <mtd> <msub> <mi>I</mi> <mi>z</mi> </msub> <msub> <mover> <mi>&omega;</mi> <mo>&CenterDot;</mo> </mover> <mi>r</mi> </msub> <mo>-</mo> <msub> <mi>I</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <mover> <mi>&phi;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mo>=</mo> <msub> <mi>N</mi> <mi>r</mi> </msub> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mo>+</mo> <msub> <mi>N</mi> <mi>&beta;</mi> </msub> <mi>&beta;</mi> <mo>+</mo> <msub> <mi>N</mi> <mi>&phi;</mi> </msub> <mi>&phi;</mi> <mo>+</mo> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <mi>&delta;</mi> </mtd> </mtr> <mtr> <mtd> <mi>m</mi> <mi>u</mi> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mo>+</mo> <mover> <mi>&beta;</mi> <mo>&CenterDot;</mo> </mover> <mo>)</mo> <mo>-</mo> <msub> <mi>m</mi> <mi>s</mi> </msub> <mi>h</mi> <mover> <mi>&phi;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mo>=</mo> <msub> <mi>Y</mi> <mi>r</mi> </msub> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mo>+</mo> <msub> <mi>Y</mi> <mi>&beta;</mi> </msub> <mi>&beta;</mi> <mo>+</mo> <msub> <mi>Y</mi> <mi>&phi;</mi> </msub> <mi>&phi;</mi> <mo>+</mo> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> <mi>&delta;</mi> </mtd> </mtr> <mtr> <mtd> <msub> <mi>I</mi> <mi>x</mi> </msub> <mover> <mi>&phi;</mi> <mo>&CenterDot;&CenterDot;</mo> </mover> <mo>-</mo> <msub> <mi>m</mi> <mi>s</mi> </msub> <mi>u</mi> <mo>(</mo> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mo>+</mo> <mover> <mi>&beta;</mi> <mo>&CenterDot;</mo> </mover> <mo>)</mo> <mi>h</mi> <mo>-</mo> <msub> <mi>I</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mover> <mi>&omega;</mi> <mo>&CenterDot;</mo> </mover> <mi>r</mi> </msub> <mo>=</mo> <msub> <mi>L</mi> <mi>p</mi> </msub> <mover> <mi>&phi;</mi> <mo>&CenterDot;</mo> </mover> <mo>+</mo> <msub> <mi>L</mi> <mi>&phi;</mi> </msub> <mi>&phi;</mi> </mtd> </mtr> </mtable> </mfenced>

<mrow> <msub> <mi>T</mi> <mi>r</mi> </msub> <mo>=</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>G</mi> <mi>p</mi> </msub> </mfrac> <mrow> <mo>(</mo> <mi>&beta;</mi> <mo>+</mo> <mfrac> <mrow> <mi>a</mi> <mi>&gamma;</mi> </mrow> <mi>u</mi> </mfrac> <mo>+</mo> <msub> <mi>E</mi> <mn>1</mn> </msub> <mi>&phi;</mi> <mo>-</mo> <mi>&delta;</mi> <mo>)</mo> </mrow> </mrow>

In formula：U is longitudinal velocity, and m is complete vehicle quality, I_zRotary inertia for car mass to z-axis, I_xIt is sprung mass to x-axis Rotary inertia, ω_rFor yaw velocity, β is side slip angle, and φ is vehicle roll angle, and α is front-wheel side drift angle, and δ is front-wheel Steering angle, I_xzIt is sprung mass to x, the product of inertia of z-axis, d is wheelspan, G_PFor screw rod to front wheel drive ratio, h is to hang barycenter extremely The distance of roll axis, N_βFor caused by unit side slip angle to the torque of z-axis, N_rFor caused by unit yaw velocity to z The torque of axle, N_φFor caused by unit roll velocity to the torque of z-axis, N_δFor caused by unit front wheel angle to the power of z-axis Square, L_pFor caused by unit roll velocity to the moment of face of x-axis, L_φFor caused by unit angle of heel to the moment of face of x-axis, Y_r For ground cornering force, Y caused by unit yaw velocity_βFor the lateral reaction in ground caused by unit vehicle side drift angle Power, Y_φFor ground cornering force, Y caused by unit angle of heel_δFor the lateral reaction in ground caused by unit front wheel angle Power, k₁For front-wheel cornering stiffness, E₁For the radian factor.
4. the Multipurpose Optimal Method of automobile hydraulic variable ratio steering according to claim 3, it is characterised in that The Performance Evaluation System established in the step (2) includes steering response, steering sensitivity and the individual character of steering energy consumption three Energy evaluation index, the steering response performance function formula are：

<mrow> <mfrac> <mrow> <msub> <mi>T</mi> <mi>h</mi> </msub> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mi>T</mi> <mi>r</mi> </msub> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>=</mo> <mfrac> <mrow> <msub> <mi>K</mi> <mrow> <mi>T</mi> <mi>T</mi> </mrow> </msub> <mi>q</mi> </mrow> <mrow> <msub> <mi>X</mi> <mn>1</mn> </msub> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <msub> <mi>Y</mi> <mn>1</mn> </msub> <mi>s</mi> <mo>+</mo> <msub> <mi>Z</mi> <mn>1</mn> </msub> </mrow> </mfrac> </mrow>

In formula：

<mrow> <msub> <mi>X</mi> <mn>1</mn> </msub> <mo>=</mo> <mi>q</mi> <mrow> <mo>(</mo> <msub> <mi>J</mi> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <mo>+</mo> <mfrac> <mrow> <msub> <mi>m</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> <mi>p</mi> <mi>l</mi> </mrow> <mrow> <mn>2</mn> <mi>&pi;</mi> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <msub> <mi>J</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <mi>p</mi> <mi>l</mi> </mrow> <mrow> <mn>2</mn> <msup> <msub> <mi>&pi;r</mi> <mi>w</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <msub> <mi>m</mi> <mi>z</mi> </msub> <msup> <msub> <mi>plr</mi> <mi>y</mi> </msub> <mn>2</mn> </msup> </mrow> <mrow> <mn>2</mn> <msup> <msub> <mi>&pi;r</mi> <mi>w</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>lA</mi> <mi>p</mi> </msub> <msub> <mi>J</mi> <mrow> <mi>m</mi> <mn>1</mn> </mrow> </msub> <msub> <mi>n</mi> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>lA</mi> <mi>p</mi> </msub> <msub> <mi>J</mi> <mrow> <mi>m</mi> <mn>2</mn> </mrow> </msub> <msub> <mi>n</mi> <mn>3</mn> </msub> <mo>+</mo> <mfrac> <mrow> <msub> <mi>m</mi> <mi>z</mi> </msub> <msub> <mi>k</mi> <mi>x</mi> </msub> <msub> <mi>r</mi> <mi>y</mi> </msub> <msup> <mi>p</mi> <mn>2</mn> </msup> <mi>l</mi> <mi>q</mi> </mrow> <mrow> <msup> <mrow> <mo>(</mo> <mn>2</mn> <mi>&pi;</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> <msup> <msub> <mi>r</mi> <mi>w</mi> </msub> <mn>3</mn> </msup> </mrow> </mfrac> </mrow>

<mfenced open = "" close = ""> <mtable> <mtr> <mtd> <mrow> <msub> <mi>Y</mi> <mn>1</mn> </msub> <mo>=</mo> <mi>q</mi> <mrow> <mo>(</mo> <msub> <mi>B</mi> <mrow> <mi>l</mi> <mi>g</mi> </mrow> </msub> <mo>+</mo> <mfrac> <mrow> <msub> <mi>B</mi> <mrow> <mi>l</mi> <mi>m</mi> </mrow> </msub> <mi>p</mi> <mi>l</mi> </mrow> <mrow> <mn>2</mn> <mi>&pi;</mi> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <msub> <mi>B</mi> <mrow> <mi>c</mi> <mi>s</mi> </mrow> </msub> <mi>p</mi> <mi>l</mi> </mrow> <mrow> <mn>2</mn> <msup> <msub> <mi>&pi;r</mi> <mi>w</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <msub> <mi>B</mi> <mi>z</mi> </msub> <msup> <msub> <mi>plr</mi> <mi>y</mi> </msub> <mn>2</mn> </msup> </mrow> <mrow> <mn>2</mn> <msup> <msub> <mi>&pi;r</mi> <mi>w</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>)</mo> </mrow> <mo>+</mo> <msub> <mi>lA</mi> <mi>p</mi> </msub> <msub> <mi>B</mi> <mrow> <mi>m</mi> <mn>1</mn> </mrow> </msub> <msub> <mi>n</mi> <mn>1</mn> </msub> <mo>+</mo> <msub> <mi>lA</mi> <mi>p</mi> </msub> <msub> <mi>B</mi> <mrow> <mi>m</mi> <mn>2</mn> </mrow> </msub> <msub> <mi>n</mi> <mn>3</mn> </msub> <mo>+</mo> <mfrac> <mrow> <msub> <mi>B</mi> <mi>z</mi> </msub> <msub> <mi>k</mi> <mi>x</mi> </msub> <msub> <mi>r</mi> <mi>y</mi> </msub> <msup> <mi>p</mi> <mn>2</mn> </msup> <mi>l</mi> <mi>q</mi> </mrow> <mrow> <msup> <mrow> <mo>(</mo> <mn>2</mn> <mi>&pi;</mi> <mo>)</mo> </mrow> <mn>2</mn> </msup> <msup> <msub> <mi>r</mi> <mi>w</mi> </msub> <mn>3</mn> </msup> </mrow> </mfrac> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>+</mo> <mfrac> <mrow> <msup> <mi>q</mi> <mn>2</mn> </msup> <msup> <msub> <mi>A</mi> <mi>p</mi> </msub> <mn>2</mn> </msup> <mi>&rho;</mi> <mi>p</mi> <mi>l</mi> </mrow> <mrow> <mn>4</mn> <msup> <msub> <mi>&pi;c</mi> <mi>q</mi> </msub> <mn>2</mn> </msup> <msup> <msub> <mi>A</mi> <mn>1</mn> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <msup> <msub> <mi>r</mi> <mi>y</mi> </msub> <mn>2</mn> </msup> <msup> <msub> <mi>plA</mi> <mrow> <mi>p</mi> <mi>l</mi> </mrow> </msub> <mn>2</mn> </msup> <msub> <mi>k</mi> <mi>x</mi> </msub> </mrow> <mrow> <mn>2</mn> <msup> <msub> <mi>&pi;r</mi> <mi>w</mi> </msub> <mn>2</mn> </msup> </mrow> </mfrac> <mo>+</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>lA</mi> <mi>p</mi> </msub> <msub> <mi>A</mi> <mrow> <mi>p</mi> <mi>l</mi> </mrow> </msub> <msub> <mi>k</mi> <mi>x</mi> </msub> <msub> <mi>r</mi> <mi>y</mi> </msub> <msup> <msub> <mi>px</mi> <mi>v</mi> </msub> <mn>2</mn> </msup> <msup> <mi>q</mi> <mn>2</mn> </msup> </mrow> <mrow> <mn>2</mn> <msub> <mi>&pi;r</mi> <mi>w</mi> </msub> </mrow> </mfrac> </mrow> </mtd> </mtr> </mtable> </mfenced>

Z₁=qk_TT+lA_pk_ak₁k_s+lA_pk_ak₂k_s；

The performance function formula of the steering sensitivity is：

<mrow> <mfrac> <mrow> <msub> <mi>&omega;</mi> <mi>r</mi> </msub> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mi>&theta;</mi> <mi>h</mi> </msub> <mrow> <mo>(</mo> <mi>s</mi> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>=</mo> <mfrac> <mrow> <msub> <mi>K</mi> <mi>s</mi> </msub> <mo>&CenterDot;</mo> <mrow> <mo>(</mo> <msub> <mi>A</mi> <mn>3</mn> </msub> <msup> <mi>s</mi> <mn>3</mn> </msup> <mo>+</mo> <msub> <mi>A</mi> <mn>2</mn> </msub> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <msub> <mi>A</mi> <mn>1</mn> </msub> <mi>s</mi> <mo>+</mo> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>)</mo> </mrow> </mrow> <mrow> <msub> <mi>Q</mi> <mn>6</mn> </msub> <msup> <mi>s</mi> <mn>6</mn> </msup> <mo>+</mo> <msub> <mi>Q</mi> <mn>5</mn> </msub> <msup> <mi>s</mi> <mn>5</mn> </msup> <mo>+</mo> <msub> <mi>Q</mi> <mn>4</mn> </msub> <msup> <mi>s</mi> <mn>4</mn> </msup> <mo>+</mo> <msub> <mi>Q</mi> <mn>3</mn> </msub> <msup> <mi>s</mi> <mn>3</mn> </msup> <mo>+</mo> <msub> <mi>Q</mi> <mn>2</mn> </msub> <msup> <mi>s</mi> <mn>2</mn> </msup> <mo>+</mo> <msub> <mi>Q</mi> <mn>1</mn> </msub> <mi>s</mi> <mo>+</mo> <msub> <mi>Q</mi> <mn>0</mn> </msub> </mrow> </mfrac> </mrow>

In formula：

<mrow> <msub> <mi>A</mi> <mn>3</mn> </msub> <mo>=</mo> <mo>-</mo> <msub> <mi>muI</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <mo>+</mo> <msup> <mi>h</mi> <mn>2</mn> </msup> <msubsup> <mi>um</mi> <mi>s</mi> <mn>2</mn> </msubsup> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <mo>-</mo> <msub> <mi>huI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> </mrow>

A₂=muL_pN_δ+I_xN_δY_β-I_xN_βY_δ

A₁=muL_φN_δ-L_pN_δY_β+L_pN_βY_δ-hum_sN_φY_δ+hum_sN_δY_φ

A₀=-L_φN_δY_β+L_φN_βY_δ

<mrow> <msub> <mi>B</mi> <mn>4</mn> </msub> <mo>=</mo> <msubsup> <mi>muI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> <mn>2</mn> </msubsup> <mo>-</mo> <msub> <mi>muI</mi> <mi>x</mi> </msub> <msub> <mi>I</mi> <mi>z</mi> </msub> <mo>+</mo> <msup> <mi>h</mi> <mn>2</mn> </msup> <msub> <mi>uI</mi> <mi>z</mi> </msub> <msup> <msub> <mi>m</mi> <mi>s</mi> </msub> <mn>2</mn> </msup> </mrow>

<mrow> <msub> <mi>B</mi> <mn>3</mn> </msub> <mo>=</mo> <msub> <mi>muI</mi> <mi>z</mi> </msub> <msub> <mi>L</mi> <mi>p</mi> </msub> <mo>+</mo> <msub> <mi>muI</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>r</mi> </msub> <mo>-</mo> <msup> <mi>h</mi> <mn>2</mn> </msup> <msubsup> <mi>um</mi> <mi>s</mi> <mn>2</mn> </msubsup> <msub> <mi>N</mi> <mi>r</mi> </msub> <mo>+</mo> <msub> <mi>hI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>N</mi> <mi>&beta;</mi> </msub> <mo>+</mo> <msub> <mi>huI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>Y</mi> <mi>r</mi> </msub> <mo>-</mo> <msubsup> <mi>I</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> <mn>2</mn> </msubsup> <msub> <mi>Y</mi> <mi>&beta;</mi> </msub> <mo>+</mo> <msub> <mi>I</mi> <mi>x</mi> </msub> <msub> <mi>I</mi> <mi>z</mi> </msub> <msub> <mi>Y</mi> <mi>&beta;</mi> </msub> </mrow>

<mfenced open = "" close = ""> <mtable> <mtr> <mtd> <mrow> <msub> <mi>B</mi> <mn>2</mn> </msub> <mo>=</mo> <msub> <mi>muI</mi> <mi>z</mi> </msub> <msub> <mi>L</mi> <mi>&phi;</mi> </msub> <mo>-</mo> <msub> <mi>muL</mi> <mi>p</mi> </msub> <msub> <mi>N</mi> <mi>r</mi> </msub> <mo>-</mo> <msub> <mi>muI</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>&beta;</mi> </msub> <mo>+</mo> <msup> <mi>h</mi> <mn>2</mn> </msup> <msubsup> <mi>um</mi> <mi>s</mi> <mn>2</mn> </msubsup> <msub> <mi>N</mi> <mi>&beta;</mi> </msub> <mo>+</mo> <msub> <mi>muI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>N</mi> <mi>&phi;</mi> </msub> <mo>+</mo> <msub> <mi>I</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>&beta;</mi> </msub> <msub> <mi>Y</mi> <mi>r</mi> </msub> <mo>-</mo> <msub> <mi>I</mi> <mi>z</mi> </msub> <msub> <mi>L</mi> <mi>p</mi> </msub> <msub> <mi>Y</mi> <mi>&beta;</mi> </msub> </mrow> </mtd> </mtr> <mtr> <mtd> <mrow> <mo>-</mo> <msub> <mi>huI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>Y</mi> <mi>&beta;</mi> </msub> <mo>-</mo> <msub> <mi>I</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>r</mi> </msub> <msub> <mi>Y</mi> <mi>&beta;</mi> </msub> <mo>+</mo> <msub> <mi>huI</mi> <mi>z</mi> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>Y</mi> <mi>&phi;</mi> </msub> </mrow> </mtd> </mtr> </mtable> </mfenced>

B₁=-muL_φN_r+muL_pN_β-L_pN_βY_r+hum_sN_φY_r-I_zL_φY_β+L_pN_rY_β-I_xzN_φY_β-hum_sN_rY_φ+I_xzN_βY_φ

B₀=muL_φN_β-L_φN_βY_r+L_φN_rY_β-hum_sN_φY_β+hum_sN_βY_φ

<mrow> <msub> <mi>F</mi> <mn>3</mn> </msub> <mo>=</mo> <mo>-</mo> <msub> <mi>hI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <mo>+</mo> <msubsup> <mi>I</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> <mn>2</mn> </msubsup> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> <mo>-</mo> <msub> <mi>I</mi> <mi>x</mi> </msub> <msub> <mi>I</mi> <mi>z</mi> </msub> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> </mrow>

<mrow> <msub> <mi>F</mi> <mn>2</mn> </msub> <mo>=</mo> <msub> <mi>muI</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <mo>-</mo> <msup> <mi>h</mi> <mn>2</mn> </msup> <msubsup> <mi>um</mi> <mi>s</mi> <mn>2</mn> </msubsup> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <mo>-</mo> <msub> <mi>I</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>&delta;</mi> </msub> <msub> <mi>Y</mi> <mi>r</mi> </msub> <mo>+</mo> <msub> <mi>I</mi> <mi>z</mi> </msub> <msub> <mi>L</mi> <mi>p</mi> </msub> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> <mo>+</mo> <msub> <mi>huI</mi> <mrow> <mi>x</mi> <mi>z</mi> </mrow> </msub> <msub> <mi>m</mi> <mi>s</mi> </msub> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> <mo>+</mo> <msub> <mi>I</mi> <mi>x</mi> </msub> <msub> <mi>N</mi> <mi>r</mi> </msub> <msub> <mi>Y</mi> <mi>&delta;</mi> </msub> </mrow>

F₁=-muL_pN_δ+L_pN_δY_r+I_zL_φY_δ-L_pN_rY_δ+I_xzN_φY_δ-I_xzN_δY_φ

F₀=-muL_φN_δ+L_φN_δY_r-L_φN_rY_δ+hum_sN_φY_δ-hum_sN_δY_φ

H₂=-muI_xzN_δ-huI_zm_sY_δ

H₁=-hum_sN_δY_r+I_xzN_δY_β+hum_sN_rY_δ-I_xzN_βY_δ

H₀=hum_sN_δY_β-hum_sN_βY_δ

Q₆=B₄X₂

Q₅=B₄Y₂+B₃X₂

Q₄=B₄Z₂+B₃Y₂+B₂X₂

<mrow> <msub> <mi>Q</mi> <mn>3</mn> </msub> <mo>=</mo> <msub> <mi>B</mi> <mn>3</mn> </msub> <msub> <mi>Z</mi> <mn>2</mn> </msub> <mo>+</mo> <msub> <mi>B</mi> <mn>2</mn> </msub> <msub> <mi>Y</mi> <mn>2</mn> </msub> <mo>+</mo> <msub> <mi>B</mi> <mn>1</mn> </msub> <msub> <mi>X</mi> <mn>2</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>F</mi> <mn>3</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <mfrac> <mi>a</mi> <mi>V</mi> </mfrac> <msub> <mi>A</mi> <mn>3</mn> </msub> </mrow>

<mrow> <msub> <mi>Q</mi> <mn>2</mn> </msub> <mo>=</mo> <msub> <mi>B</mi> <mn>2</mn> </msub> <msub> <mi>Z</mi> <mn>2</mn> </msub> <mo>+</mo> <msub> <mi>B</mi> <mn>1</mn> </msub> <msub> <mi>Y</mi> <mn>2</mn> </msub> <mo>+</mo> <msub> <mi>B</mi> <mn>0</mn> </msub> <msub> <mi>X</mi> <mn>2</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>F</mi> <mn>2</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <mfrac> <mi>a</mi> <mi>V</mi> </mfrac> <msub> <mi>A</mi> <mn>2</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>E</mi> <mn>1</mn> </msub> <msub> <mi>H</mi> <mn>2</mn> </msub> </mrow>

<mrow> <msub> <mi>Q</mi> <mn>1</mn> </msub> <mo>=</mo> <msub> <mi>B</mi> <mn>1</mn> </msub> <msub> <mi>Z</mi> <mn>2</mn> </msub> <mo>+</mo> <msub> <mi>B</mi> <mn>0</mn> </msub> <msub> <mi>Y</mi> <mn>2</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>F</mi> <mn>1</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <mfrac> <mi>a</mi> <mi>V</mi> </mfrac> <msub> <mi>A</mi> <mn>1</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>E</mi> <mn>1</mn> </msub> <msub> <mi>H</mi> <mn>1</mn> </msub> </mrow>

<mrow> <msub> <mi>Q</mi> <mn>0</mn> </msub> <mo>=</mo> <msub> <mi>B</mi> <mn>0</mn> </msub> <msub> <mi>Z</mi> <mn>2</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>F</mi> <mn>0</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <mfrac> <mi>a</mi> <mi>V</mi> </mfrac> <msub> <mi>A</mi> <mn>0</mn> </msub> <mo>+</mo> <mfrac> <mrow> <mi>q</mi> <mi>l</mi> </mrow> <msub> <mi>r</mi> <mi>w</mi> </msub> </mfrac> <mo>&CenterDot;</mo> <mfrac> <mrow> <mn>2</mn> <msub> <mi>dk</mi> <mn>1</mn> </msub> </mrow> <msub> <mi>n</mi> <mn>2</mn> </msub> </mfrac> <msub> <mi>E</mi> <mn>1</mn> </msub> <msub> <mi>H</mi> <mn>0</mn> </msub> </mrow>

The performance function formula of the steering energy consumption is：

E=P_ECU-loss+2P_motor-loss+2P_pump-loss+2P_v-loss

In formula：

Represent controller energy consumption；

P_motor-loss=M_c+C_Frω+C_Fr2ω²+ C, represent energy consumption of electrical machinery；

P_pump-loss=P_pump-in-P_pump-out, represent hydraulic pump energy consumption；

Represent hydraulic valve energy consumption；

In formula：R_AFor armature resistance, I_AFor armature supply, U_sFor controller both end voltage, R_elecFor controller resistance, M_cFor motor Torque loss caused by middle friction, C_FrIt is speed than coefficient of friction, ω is motor speed, C_Fr2For fast ratio square coefficient of friction, C is Motor unknown losses.
5. the Multipurpose Optimal Method of automobile hydraulic variable ratio steering according to claim 4, it is characterised in that In the step (3), mechanical configuration parameter and hydraulic parameter that optimized variable selection has a great influence to steering behaviour are made, including： The rotary inertia J of hydraulic booster motor_m1, direct current generator rotary inertia J_m2, torque sensor rigidity k_s, double-acting vane pump it is fixed Sub- thickness B, double-acting vane pump major axis radius R₂, tooth fan pitch radius r_w；

Object function is：

<mrow> <mi>f</mi> <mrow> <mo>(</mo> <mi>x</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <msub> <msup> <mi>k</mi> <mo>&prime;</mo> </msup> <mn>1</mn> </msub> </mrow> <mrow> <mi>f</mi> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>1</mn> </msub> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>+</mo> <msub> <msup> <mi>k</mi> <mo>&prime;</mo> </msup> <mn>2</mn> </msub> <mi>f</mi> <mrow> <mo>(</mo> <msub> <mi>x</mi> <mn>2</mn> </msub> <mo>)</mo> </mrow> </mrow>

In formula：k'₁、k'₂For weight coefficient；

Represent steering response；

f(x₂)=P_ECU-loss+2P_motor-loss+2P_pump-loss+2P_v-loss, represent system energy consumption；

Constraints is：

Take ω₀=45Hz so that functionMeet 0.0011≤f (x₃)≤0.0081, ensure Steering sensitivity is in zone of reasonableness.
6. the Multipurpose Optimal Method of automobile hydraulic variable ratio steering according to claim 5, it is characterised in that The genetic algorithms of NSGA- II of technology of sharing, are comprised the following steps that between mixing microhabitat colony in the step (4)：

Step 4.1：Using binary coding method to chromosome coding, the solution space of problem is converted into and meets genetic algorithm The search space of processing requirement, initiation parameter；

Step 4.2：Randomly generate new population Q_t, at the t=0 moment, N number of feasible solution Y is randomly generated, brings feasible solution into the mesh Scalar functions f (x), calculate local congestion distance L [k] d=L between individual adaptation degree F' and individual corresponding with target function value [k] d+L [k+1] m-L [k+1] m, according to obtained individual adaptation degree, by population Q_tIt is divided into several sub-group P_K, k=1,2, 3......；

Step 4.3：Each sub-group independently evolve and perform selection, intersect and mutation operation, so as to get solution be uniformly distributed, obtain Population Q of new generation_t+1；The local congestion distance obtained using the algorithms of NSGA- II is to Q_t+1Individual carry out quick non-dominated ranking, Obtained result and parent Q_tMerge, then keep strategy to select individual composition new population Q' with elite_t+1, make optimization The direction optimal towards Pareto is carried out；

Step 4.4：By new population Q'_t+1Initial population as niche algorithm, it is assumed that individual i ∈ S, S are to share colony, j ∈ O, O are other colonies, and Max size are total group number；According to Calculate colony and share fitness S, according to the average fitness of each sub-group, select averagely suitable The best sub-group of response shares colony as microhabitat；

Step 4.5：Defect individual selected in Max size*15% ratios to each sub-group, calculates defect individual between colony Hamming distances

Step 4.6：Based on shared mechanism between microhabitat colony, the similarity between defect individual is judged according to Hamming distances, is adjusted The fitness of shared sub-group isThe fitness of other sub-groups is

Step 4.7：By the adjusted sub-group of fitness, using the elitism strategy of the quick non-dominated ranking of the algorithms of NSGA- II, wash in a pan Eliminate and show poor sub-group, reselect and produce new sub-group P'_K,K=1,2,3......, and form new population Q "_t+1；

Step 4.8：Population is evaluated, if number of iterations reaches defined maximum or meets the condition of convergence, terminates to optimize, Otherwise circulation step 4.4 is to step 4.7；

Step 4.9：Chromosome is decoded, and disaggregation is sorted to obtain optimal pareto disaggregation.