Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D12/00—Steering specially adapted for vehicles operating in tandem or having pivotally connected frames
  • B62D12/02—Steering specially adapted for vehicles operating in tandem or having pivotally connected frames for vehicles operating in tandem
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62D—MOTOR VEHICLES; TRAILERS
  • B62D47/00—Motor vehicles or trailers predominantly for carrying passengers
  • B62D47/006—Vehicles which can be divided in sub-vehicles; nestable vehicles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60D—VEHICLE CONNECTIONS
  • B60D1/00—Traction couplings; Hitches; Draw-gear; Towing devices
  • B60D1/48—Traction couplings; Hitches; Draw-gear; Towing devices characterised by the mounting
  • B60D1/481—Traction couplings; Hitches; Draw-gear; Towing devices characterised by the mounting adapted for being mounted to the front and back of trailers, carts, trolleys, or the like to form a train

Definitions

• the invention lies in the field of the stabilization of a convoy of mechanically coupled vehicles and relates to a method of stabilization by orientation of a vehicle convoy.
• the invention also relates to a convoy of vehicles connected two by two one behind the other.
• the self-service vehicles provided for this purpose and thus form a convoy of several vehicles, for example two, three or eight or more , the convoy being driven by a single driver.
• the invention is illustrated in this case but is not limited to the application to self-service vehicles and can be applied to any type of vehicle convoy.
• This type of vehicle convoy presents a problem of stability. Indeed, during the setting in motion of the convoy, the connected vehicles can perform unwanted lateral oscillations. These oscillations are more or less important depending on the trajectory of the convoy and its speed. This oscillation is dangerous, difficult to control and can lead to the complete loss of control of the convoy. At the extreme, it can result in the convoy's portfolio, that is to say that one of the vehicles of the convoy forms an acute angle with another of the vehicles of the convoy, such as a folded wallet. Other situations can generate such oscillations. One can cite in particular a trajectory of avoidance of successive obstacles requiring the circumvention of the obstacles by the entire convoy, involving oscillations of the vehicles of the convoy. On a slope, it is also possible that a convoy of vehicles is deformed. Similarly, a strong side wind can cause the convoy to oscillate.
• the invention aims to overcome all or part of the problems mentioned above by proposing a method of controlling a convoy of vehicles connected two by two one behind the other, to detect the slightest difference between the actual trajectory and the desired reference path so as to correct if necessary the position and / or orientation of each of the vehicles, before the appearance of lateral oscillations.
• a head vehicle capable of moving along a main axis, comprising a two-wheeled front train capable of being oriented along an axis of orientation forming an orientation angle with the main axis, where a two-wheeled rear axle is rotatable about a rear axle;
• a first sensor intended to estimate a position and an orientation of the leading vehicle
• At least one second vehicle comprising:
• a hinge configured to make the mobile rear axle rotate about a vertical axis substantially perpendicular to the reference plane relative to the nose gear
• the method according to the invention comprising the following steps:
• the trajectories are represented by components comprising the position and the orientation of the leading vehicle and for each second vehicle by a relative orientation corresponding to the orientation of the second vehicle with respect to the orientation of the vehicle which precedes it, and the determination of the difference between the real trajectory and the reference trajectory consists in calculating for each vehicle: • the difference between the components of its real trajectory and the components of its reference trajectory,
• the calculation of the first control vector is performed by means of a quadratic linear control method.
• a step of calculation by the computer of a second control vector comprising for each vehicle a second correction component to be applied to the rear axle of said vehicle, multiplied by a second coefficient of between 0 and 1, the sum of the first coefficient and the second coefficient being equal to 1, so as to minimize the difference between the real trajectory and the reference trajectory,
• the second correction component comprises a torque to be applied to the wheels of the rear axle of said vehicle.
• the stabilization method according to the invention comprises, for each vehicle, a step of distributing the torque to be applied to the rear axle of said vehicle in a first force to be applied to a first of the two wheels of the rear axle of said vehicle. and in a second force to be applied on a second of the two wheels of the rear axle of said vehicle.
• the calculation of the correction components is carried out in real time.
• the calculation of at least one correction component is carried out only once during a predefined period, and the at least one correction component is estimated by linear interpolation between the adjacent correction components of its component. control vector during the predefined period.
• each second vehicle comprising an actuator adapted to apply to the articulation a force to the rotation of the rear axle relative to the front axle of said vehicle
• the stabilization method according to the invention comprises, if the deviation between the actual trajectory and the reference trajectory is greater than a predefined value:
• a step of calculation by the computer of a third control vector comprising for each second vehicle a third correction component to be applied to the articulation of said second vehicle, so as to minimize the difference between the real trajectory and the trajectory of the second vehicle; reference,
• a step of applying the third control vector by the actuator on the articulation of said vehicle is a step of applying the third control vector by the actuator on the articulation of said vehicle.
• the stabilization method according to the invention comprises, prior to the application of the control vector, a step of saturation of the control vector to be applied to said vehicle.
• the invention also relates to a convoy of vehicles connected two by two one behind the other, intended to move on a reference plane along a reference trajectory, the convoy of vehicles following a real trajectory, the convoy comprising:
• a leading vehicle capable of moving along a principal axis comprising
• a front axle with two wheels capable of being oriented along an axis of orientation forming with the main axis an angle of orientation
• a first sensor intended to estimate a position and an orientation of the leading vehicle
• At least one second vehicle comprising:
• a hinge configured to make the mobile rear axle rotate about a vertical axis substantially perpendicular to the reference plane relative to the nose gear
• the convoy being configured to implement such a stabilization method.
• FIG. 1 a schematically represents an embodiment of a convoy of vehicles according to the invention
• FIG. 1 b schematically represents a vehicle in plan view according to the invention
• FIG. 1 c schematically represents a convoy with three vehicles in plan view according to the invention
• FIG. 2 diagrammatically represents the steps of an embodiment of a control method according to the invention
• FIG. 3 schematically represents the steps of another embodiment of a control method according to the invention
• FIG. 4 schematically represents the steps of another embodiment of a control method according to the invention
• FIG. 5 diagrammatically represents the steps of another embodiment of a control method according to the invention.
• FIG. 6 represents an equation giving the difference between the real trajectory and the reference trajectory of the vehicle convoy.
• the invention is described with the example of a train consisting of three vehicles.
• the invention is applicable to a train more generally comprising a plurality of vehicles, that is to say at least one leading vehicle and a follower vehicle or several follower vehicles one behind the other.
• follower vehicle one understands a vehicle which can be advantageously also a vehicle of head, but the follower vehicle can also be passive, that is to say without capacity of piloting, for example a trailer.
• FIG. 1a shows schematically an embodiment of a convoy 10 of vehicles according to the invention.
• the convoy 10 comprises vehicles 1 1, 12 connected in pairs one behind the other, intended to move on a reference plane 13 in a reference path, the convoy 10 of vehicles in a real trajectory.
• the convoy 10 comprises a head vehicle 1 1 adapted to move along a main axis 1 6, comprising a front axle 14 with two wheels 17, 18 adapted to be oriented along an axis of orientation 22 forming with the main axis 1 6 an orientation angle 25, a rear axle 15 with two wheels 19, 20 movable in rotation about a rear axle 27, a first sensor 7 for measuring a position and an orientation of the head vehicle 1 1.
• the term first sensor is to be taken in the broad sense.
• the first sensor 7 may be a measurement sensor, for example a GPS or an inertial unit, but it may also be a means for estimating the position and orientation of the head vehicle 1 1, allowing to make an estimation based on the rotation of the wheels and the steering angles, possibly with the help of a gyrometer.
• the head vehicle 1 1 does not necessarily have hinge 21 since it is the towing vehicle and therefore it does not require rotational mobility of the rear train relative to the nose gear.
• the invention applies similarly to a head vehicle 11 with a hinge 21. It is even advantageous to have a vehicle 1 1 head identical to the second vehicles 12. In other words, all vehicles are advantageously identical.
• the driver in a self-service vehicle station, the driver can use any vehicle 12 as a head vehicle 1 1, thus facilitating the logistics aspect of the vehicle fleet.
• the vehicle 12 serving as the head vehicle has its hinge 21 blocked.
• the hinge 21 is configured such that the angle 26 is zero.
• the front wheels 17, 18 of the second vehicles 12 are nominally configured such that the angle 25 is zero, that is to say that the front wheels 17, 18 are oriented along the main axis 16, but possibly the wheels 17 , 18 may be oriented at a small angle for convoy stabilization purposes, as explained below.
• the reference trajectory of the convoy is composed by the actual trajectory of the leading vehicle 1 1 and the trajectory of the second vehicles 12 driven by the head vehicle 1 1 and to which no external force is applied. In other words, the reference trajectory is described by the trajectory of the leading vehicle 1 1 and the trajectory of the second vehicles 12 which follow the head vehicle 1 1 as they can, without constraints or external forces.
• the reference trajectory comes from kinematics and represents a unique configuration.
• the computer 9 is positioned in the head vehicle 1 1 and communicates wired or wireless with the sensors 7, 8.
• each vehicle 1 1, 12 may include a computer 9.
• the computers 9 of each vehicle can calculate a path and communicate with each other, by wire or wireless.
• FIG. 2 schematically represents the steps of an embodiment of a control method according to the invention.
• the method according to the invention comprises the following steps.
• the method comprises a step 100 of estimation by the sensors 7, 8 of the position of the leading vehicle 1 1 and the orientation of the vehicles 1 1, 12.
• the sensors 7, 8 can be estimation means for estimating the position and orientation of the vehicles. They may also be measurement sensors, in which case the estimation step 100 corresponds to a step of measuring the position and the orientation of the vehicles.
• the sensor 7 measures the position of the leading vehicle 1 1 and each of the sensors 8 measures the position and orientation of the vehicle 1 1, 12 with which it is associated.
• This position and orientation information is transmitted, wired or wireless, to the computer 9.
• the method according to the invention comprises a step 101 of determination by the computer 9 of the difference between the real trajectory and the reference trajectory from the estimates of the sensors 7, 8.
• the computer 9 is configured to determine the reference trajectory from the trajectory of the leading vehicle 1 1 and kinematic equations.
• the computer 9 is able to calculate the actual trajectory of the convoy 10 from the position and the orientation of the second vehicles 12.
• FIG. 6 represents an equation giving the difference 50 between the real trajectory and the reference trajectory of the vehicle convoy.
• the index "ref” refers to the reference trajectory.
• the vector 51 denoted h is a vector comprising the orientation of a vehicle and its position, h index “ref” is therefore the vector comprising the orientation and the position of a vehicle for its reference trajectory and h is the vector including the orientation and position of a vehicle for its actual trajectory.
• the angle 52 is the difference in orientation 26 of the vehicle considered with respect to the preceding vehicle. For example for the second vehicle 12 in the second position of the convoy, the angle 52 corresponds to the difference of orientation 26 of the second vehicle with respect to its previous, that is to say the leading vehicle 1 1. The angle 52 therefore takes as value the difference between the angle 26 of the second vehicle 12 and the angle 26 of the leading vehicle 11.
• the difference 50 is thus calculated by considering in pairs all the vehicles 1 1, 12 of the convoy 10.
• the portion 53 of the difference 50 corresponds to the values mentioned above and the portion 54 of the difference 50 corresponds to the time derivatives of the values mentioned above.
• the trajectories are represented by components 53 comprising the position and the orientation of the leading vehicle 11 and for each second vehicle 12 by a relative orientation corresponding to the orientation of the second vehicle 12 with respect to the orientation of the vehicle. precedes it, and the determination of the difference 50 between the real trajectory and the reference trajectory consists in calculating for each vehicle the difference between the components of its real trajectory and the components of its reference trajectory (part 53) and the difference between the temporal derivative of the components of its real trajectory and the temporal derivative of the components of its reference trajectory (part 54).
• the axes of rotation 27 of the rear axle 15 of the preceding vehicle and the axes of rotation 28 of the wheels of the front axle of the follower vehicle are merged.
• a change in the direction of the steered wheels 17, 18 destroys this collinearity and causes a relative slippage.
• the orientation of the wheels 17, 18, that is to say the value of the first correction component is low, this skid remains tolerable, for example less than 15 degrees.
• the first correction component of each second vehicle is less than 5 degrees.
• the kinematic model of the convoy can be represented by a set of constraints by imposing the longitudinal speed on the leading vehicle, that there is no lateral speed at the wheels and that there is the same speed in translation at the level of articulation of two successive vehicles.
• the kinematic model makes it possible to determine the kinematic torsors of each vehicle, each kinematic torsor comprising the angular velocity of the vehicle and a 2D translation velocity vector.
• the dynamic model is constructed in a modular way considering all vehicles as rigid solids coupled by dynamic constraints.
• the dynamic model does not include a model of longitudinal wheel-ground behavior, considered perfect. Only a model of lateral wheel-ground behavior is considered.
• the dynamic model makes it possible to determine the dynamic torsors of each vehicle, each dynamic torsor including the moment of the vehicle and a 2D force velocity vector.
• the calculation of the first correction components can be performed in real time.
• the calculation of at least a first correction component can be performed once during a predefined period, and the at least one correction component is estimated by linear interpolation between the adjacent correction components of its correction vector. command during the predefined period. Linear interpolation limits the computation time of the first control vector.
• the quadratic linear control method does not deal with the limitation of orientation angles 25.
• a last saturation stage limits the control as a function of maximum speeds and amplitudes of orientation.
• the method according to the invention therefore advantageously comprises a step 103 of saturation of the first control vector to be applied to said vehicle.
• the method comprises a step 104 of applying the first control vector to the two wheels of the front axle of each second vehicle so as to minimize the difference between the real trajectory and the reference trajectory. It is therefore the application of the first control vector as initially calculated, to which each calculated component, that is to say the first correction components, has been multiplied by the first coefficient and then saturated.
• the method according to the invention makes it possible to obtain a correction in the form of an orientation angle of the wheels of one, two or more second vehicles 12.
• the wheels of all the second vehicles can therefore receive a correction command of their orientation angle.
• the method comprises a step 100 of estimation (or measurement) by the sensors 7, 8 of the position of the head vehicle 11 and the orientation Vehicles 1 1, 12.
• the sensor 7 estimates (or measures) the position of the leading vehicle 1 1 and each of the sensors 8 estimates (or measures) the position and orientation of the vehicle 8 with which it is associated.
• This position and orientation information is transmitted wired or wirelessly to the computer 9.
• the method according to the invention comprises a step 101 of determination by the computer 9 of the difference between the real trajectory and the reference trajectory from the estimates or measurements of the sensors 7, 8.
• the computer 9 is configured to determine the reference trajectory from the trajectory of the leading vehicle 1 1 and kinematic equations.
• the computer 9 is able to calculate the actual trajectory of the convoy 10 from the position and the orientation of the second vehicles 12.
• each of the two wheels 19, 20 of the rear axle 15 of each vehicle January 1, 12 comprises a motorization means and a brake.
• the drive means are independent and the brake of each wheel can be controlled independently.
• the method according to the invention comprises a step 202 of calculation by the computer 9 of a second control vector comprising for each vehicle 1 1, 12 a second correction component to be applied to the rear axle 15 of said vehicle.
• the second correction component comprises a torque to be applied to the wheels of the rear axle of said vehicle.
• the second control vector is calculated following the same approach as that of the calculation of the first control vector. By solving the aforementioned equations, it is then possible to calculate the second control vector using a quadratic linear control method.
• the second control vector corresponds to a torque to be applied to the rear axle of the vehicles.
• the method according to the invention comprises for each vehicle a step 205 of distribution of the torque to be applied to the rear axle 15 of said vehicle in a first force to be applied to a first of the two wheels of the rear axle 15 of said vehicle and in a second force to apply on a second of the two wheels of the rear axle 15 of said vehicle.
• the method according to the invention can provide a correction corresponding to the control which calculates a translational force and a target torque which result in pairs on the wheels, which can be positive or negative independently. Activation of the motorization means and / or the brake of at least one wheel of the rear train is done to meet the trajectory correction needs to be made to the convoy of vehicles.
• the activation of the motorization means and / or the brake of at least one wheel of the rear axle which results from the calculation of the second control vector, can intervene to correct the speed, the acceleration or deceleration of the convoy, but also this activation can intervene to reduce the difference between the real trajectory and the reference trajectory of the convoy of vehicles, therefore not necessarily for a correction in terms of speed or speed variations, but simply in terms of positioning of the vehicles.
• the limitations or saturations of controls must take into account the aspects of asymmetry for the same wheel between the maximum engine torque (provided by the means of motorization of the wheel whose maximum torque decreases as a function of speed) and the maximum resistant torque, depending mainly on braking, more important in absolute value.
• the control limitations or saturations must also take into account the coupling management aspects between propulsion (that is to say a longitudinal force) and the moment for the stabilization of the convoy 10. It is chosen to favor stabilization, the moment calculated by the calculator. Once this value of moment calculated, it is distributed at best on the two wheels according to the saturations, managed on each wheel.
• the propulsion control is calculated in a second time, which implies that the convoy of vehicles can be braked or slowed down if the stabilization requires it even if in terms of propulsion, it would be necessary to accelerate.
• the calculation of the second correction components can be performed in real time.
• the calculation of at least one second correction component can be performed once during a predefined period, and the at least one correction component is estimated by linear interpolation between the adjacent correction components of its correction vector. command during the predefined period. Linear interpolation limits the computation time of the first control vector. This saving of computation time is very important since the application of the course corrections to be made to the convoy 10 must be very reactive in order to correct the trajectory as soon as a smaller deviation appears.
• the second correction component to be applied to the rear axle 15 is multiplied by a second coefficient of between 0 and 1, the sum of the first coefficient and the second coefficient being equal to 1.
• the weighting by the second coefficient is intended to couple the second control vector to the first control vector, as previously mentioned.
• the control method may consist of a linear combination of the first and second control vectors.
• the values taken by the first and second coefficients make it possible to combine the two corrections to be made (on the orientation of the wheels of the front axle and on the torque and the braking applied to the rear axle).
• the linear combination of these two corrections makes it possible to favor one of the two corrections, for example the orientation of the wheels 17, 18 by giving the first coefficient a value closer to 1.
• the values assigned to the first and second coefficients are adjustable over time, depending on the type of correction desired, depending on whether one wishes to emphasize the orientation of the wheels of the front axle or on the torque and / or braking of the wheel. rear axle.
• This linear combination also makes it possible to disconnect one of the corrections, by assigning a zero value to the associated coefficient. For example, if one does not wish to change the orientation of the wheels of the train of the second vehicles, it suffices to set the first coefficient to 0.
• the combination of the two corrections allows a more effective trajectory correction since it combines two correctors , both the angle of orientation of the wheels and the torque to be applied to the rear axle, which allows the vehicle convoy to stay as close to the reference trajectory in terms of positioning and speed.
• a last stage of saturation limits the control according to the maximum torque.
• the method according to the invention therefore advantageously comprises a step 203 of saturation of the second control vector to be applied to said vehicle.
• the method comprises a step 204 for applying the second control vector, by the motorization means and / or the brake to the rear axle of said vehicle, so as to minimize the difference between the real trajectory and the reference trajectory. . It is therefore the application of the second control vector as initially calculated at which each computed component, that is to say the second correction components, has been multiplied by the second coefficient, and then saturated.
• FIG. 4 schematically represents the steps of another embodiment of a control method according to the invention.
• This embodiment is described in this figure as an isolated and independent embodiment of the embodiments presented in FIGS. 2 and 3.
• this embodiment of the control method can also be implemented in combination, successively or in parallel, with the embodiment shown in Figure 2 and / or the embodiment shown in Figure 3.
• each second vehicle 12 comprises an actuator adapted to applying on the articulation 21 a force resistant to the rotation of the rear axle 15 relative to the front axle 14 of said vehicle.
• the method comprises, if the difference between the real trajectory and the reference trajectory is non-zero or greater than a predefined value, a step 302 of calculation by the computer 9 of a third control vector comprising for each second vehicle 12 a third correction component to be applied to the hinge 21 of said second vehicle, so as to minimize the difference between the real trajectory and the reference trajectory.
• This correction is based on a cylinder controlled in resistant force. It is a passive actuator, with the advantage of consuming little energy. Unlike an active actuator, this jack does not apply a required effort, but only a force resistant to movement, equal to the desired effort when the movement is effective, and less than the desired effort (or zero) when there is no movement. We can, in a simplified way, represent this control as a dry friction whose maximum value of effort is controlled.
• the action of the jack is not to act so that the angle 26 is between a minimum value and a maximum value allowed, but to apply a force resistant to movement.
• the load applied is not necessarily related to the angle of orientation of the wheels 17, 18.
• the resistant force applied may be determined in particular by the type of jack used.
• the jack may be hydraulic type, with a valve held by a spring. Pressure is then applied to the valve and beyond a certain preset pressure, the valve moves and there is movement of the cylinder. The pressure can be applied in one direction or another.
• a last stage of saturation limits the command according to the maximum damping.
• the method according to the invention therefore advantageously comprises a step 303 of saturation of the third control vector to be applied to said vehicle.
• the method comprises a step 304 of applying the third control vector by the actuator on the articulation of said vehicle.
• FIG. 5 schematically represents the steps of another embodiment of a control method according to the invention.
• This figure illustrates the possible combinations between the various embodiments of a control method.
• Each embodiment can be implemented individually. Or it is possible to cumulate two, for example the calculation of the first control vector and the calculation of the second control vector or the calculation of the first control vector and the calculation of the third control vector, or the calculation of the second control vector.
• the three approaches complement each other without the need to favor one or the other.
• the invention is based on the fact that the convoy does not oscillate. Indeed, the oscillations can not develop since as soon as a smaller deviation is detected, the control method is immediately implemented.
• the invention also relates to a convoy configured to implement a control method as described above. More specifically, the computer 9 is configured to implement such a method. For reasons of ease of logistics, it is interesting that all vehicles are identical, but it can be noted that the presence of a calculator in each vehicle is not mandatory.
• the invention applies with at least one computer 9 in the overhead vehicle. In this case, the sensors of the second vehicles communicate their data to the computer 9.

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=57286647

Family Applications (1)

Country Status (4)

Families Citing this family (2)

Family Cites Families (1)

• 2016
  • 2016-08-26 FR FR1657959A patent/FR3055284B1/fr active Active
• 2017
  • 2017-07-18 EP EP17737843.7A patent/EP3504108A1/de not_active Withdrawn
  • 2017-07-18 WO PCT/EP2017/068122 patent/WO2018036723A1/fr unknown
  • 2017-07-18 US US16/325,708 patent/US20210354753A1/en not_active Abandoned

Also Published As

Similar Documents

Legal Events