WO2021008241A1 - 车用转向方法、***、行驶机构的转向方法及行驶机构 - Google Patents
车用转向方法、***、行驶机构的转向方法及行驶机构 Download PDFInfo
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- WO2021008241A1 WO2021008241A1 PCT/CN2020/092623 CN2020092623W WO2021008241A1 WO 2021008241 A1 WO2021008241 A1 WO 2021008241A1 CN 2020092623 W CN2020092623 W CN 2020092623W WO 2021008241 A1 WO2021008241 A1 WO 2021008241A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D6/00—Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits
Definitions
- the invention relates to the principle of vehicle steering, in particular, to a vehicle steering method, a vehicle steering system, and a traveling mechanism including the vehicle steering system.
- the first type is the traditional vehicle steering system, which consists of three parts: steering control mechanism, steering gear and steering transmission mechanism.
- a hydraulic or electric power steering or power system is also required to achieve steering assistance or automatic control.
- the second type is differential steering, where the wheels cannot be deflected, and the vehicle realizes steering by separately controlling the rotation speed of the left and right driving wheels. Commonly used on tracked vehicles or other wheeled special vehicles.
- the third type is the steering system of the steering gear. Each wheel is equipped with an independent steering gear. The steering gear can control the deflection of the wheel to realize the independent deflection angle of each wheel.
- the current steering mode has the following defects:
- the first type of driving mechanism steering method has the following defects.
- the steering system of this type of vehicle is still a traditional steering system, and a steering torque needs to be applied through the steering control mechanism and transmitted to the steering transmission mechanism through the steering gear to control the steering wheel deflection.
- the power source for steering is still a human driver or a dedicated steering motor.
- the second type of driving mechanism steering method has the following defects: the differential steering system makes the car body steer by controlling the rotation speed of the wheels on both sides, which causes the wheels to produce larger lateral slip, the tires are worn seriously, and the resistance is large. Higher requirements for power systems and vehicles.
- the third type of driving mechanism steering method has the following defects: the steering gear steering system is equipped with a dedicated steering steering gear for each wheel, resulting in a complicated system, a large space occupation, and a high cost.
- the first object of the present invention is to provide a vehicle steering method and vehicle steering system.
- the second object of the present invention is to provide a steering method of a traveling mechanism and a traveling mechanism.
- a vehicle steering method for distributed driving control of the wheels including: the steering wheel is directly or indirectly applied to the steering wheel by the distributed driving power source directly or indirectly, and the driving force in the opposite direction is generated between the steering wheel and the contact surface,
- the driving force generates a rotational torque T spin on the steering shaft of the steering wheel, and after overcoming the frictional resistance torque of the steering wheel around the steering shaft, such as the frictional resistance torque of the steering wheel around the steering shaft and the contact surface of the steering wheel and the steering wheel, it causes the The steering wheel rotates around the steering shaft of the wheel.
- the overall dynamic balance of the vehicle can be calculated, including at least one of the driving force, resistance, and centrifugal force, so that the vehicle can achieve a desired state of motion.
- the method also includes: setting a yaw moment T bias around the steering shaft of the steering wheel, which generates a corresponding moment that makes the wheel reach a stable state when the wheel deviates to a desired position, so as to form a stable steering.
- the yaw moment can change correspondingly with the change of the wheel yaw angle, and the direction of the rotation moment is always opposite when the wheel is yaw.
- the yaw moment is any torque value that allows the wheel to deflect; when the wheel is turned to the desired position, the yaw moment will be set to the torque that can maintain the wheel at this position.
- a deflection control element that can produce deformation is arranged between at least one connection point B and the vehicle body.
- the deflection control element When the wheel is pointing straight ahead, the deflection control element is in a free state and does not generate tension or pressure.
- the deflection control element is pulled or stretched a tensile force F / F, and a pressure is compressed pressure, controlling the steering wheel about the steering wheel shaft.
- the present invention has the following beneficial effects:
- the present invention utilizes the characteristic that the torque of each wheel of a distributed drive vehicle can be independently controlled. Instead of using a dedicated steering motor or a human driver as the power source for steering, it uses the forward or backward driving force of each wheel as the steering force.
- the power source can realize vehicle steering in a low-cost, simple, robust and sensitive way; controlling the magnitude of the force can be used to generate driving force between the steering wheel and the contact surface, without complicated steering gear and steering transmission mechanism,
- the structure is simple and does not take up a lot of space.
- the present invention can individually control the deflection angle of each steering wheel to better meet the overall steering demand of the vehicle;
- the steering wheels of the present invention do not need to be physically connected, which is conducive to the modular layout of the vehicle, which will greatly improve the space utilization efficiency of the vehicle, shorten the development cycle, and save the development cost.
- Figure 1 is a schematic diagram of vehicle steering based on Ackerman's theory
- Figure 2 is a left view of the force analysis of a single wheel in the present invention
- Figure 3 is a top view of the force analysis of a single wheel in the present invention.
- Figure 4 is a top view of the elastic element in the present invention being stressed
- Figure 5 is a top view of the elastic element in the present invention in another direction where the force is applied;
- 6A-6D are schematic diagrams of the whole vehicle steering in the present invention.
- FIG. 7 is a schematic diagram of the structure of the steering wheel in the present invention.
- Figure 8 is a schematic diagram of the entire vehicle structure of the steering system in the present invention.
- Figure 9 is a schematic diagram of an elastic element in a modification of the present invention.
- FIG. 10 is a flowchart of the vehicle steering method in the present invention.
- Fig. 11 is an example diagram of using an active air spring to make a deflection control element.
- the traveling mechanism includes various devices that can cause the object to move or displace, including but not limited to various wheeled or crawler-type mechanisms.
- the steering mechanism includes the control of various wheeled or crawler-type vehicles.
- the present invention is also based on Ackerman's theory.
- Ackerman steering geometry design when turning along a curve, the centers of the four wheel paths roughly meet on the extension line of the rear axle, so that the vehicle can turn smoothly, as shown in Figure 1.
- the traditional automobile steering system applies steering force to the wheel knuckles through the steering transmission mechanism, thereby generating torque that deflects the wheels.
- the present invention combines the characteristics of distributed driving that each wheel can independently control the driving torque, and proposes a new steering torque source and steering mode.
- the driving force of the steering wheel drives the wheels to deflect.
- the vehicle dynamics factors are simplified. For example, the lateral force of the tire, the kingpin inclination angle, and the tire deformation are not considered.
- the actual development and application can be based on The simplified model adds a balanced design that considers various related parameters.
- the specific description is as follows: when the distributed power source applies a counterclockwise torque T drive to the wheels (as shown in the left view of Fig. 2), the contact surface will give the wheels a driving force F to the left. In the top view on the right, the wheel deflects around the vertical wheel steering shaft (king pin) at point A.
- the driving force F from the ground to the tire will produce a rotational torque T spin on the steering shaft (king pin) of the wheel.
- T spin the magnitude of the driving force F can be controlled, thereby indirectly controlling the magnitude of the steering torque T spin .
- T spin is greater than T resistance , if the system has no other torque around the wheel steering axis (kingpin), the wheel will continue to deflect until the limit of the mechanical position.
- the vehicle steering vehicle mentioned later can be a device that contains 4 or more wheels to match the torque to achieve the desired driving, including unmanned vehicles, manned vehicles and other tools with driving functions, or simulation or Toys, models, etc. with similar functions.
- this example can also be applied to a device or system that has a movable wheel type or partial wheel type to complete the mobile function.
- the driving power source mentioned in the present invention includes a power source (such as a drive motor) that provides a torque consistent with the rotation direction of the wheel, and also includes a power source (such as a brake system) that provides a torque that is opposite to the rotation direction of the wheel.
- a power source such as a drive motor
- a power source such as a brake system
- a vehicle steering method for distributed driving control of the wheels including: the steering wheel is directly or indirectly applied to the steering wheel by the distributed driving power source to generate the driving force between the steering wheel and the contact surface.
- the driving force generates a rotational torque T spin on the steering shaft of the steering wheel, and overcomes the frictional resistance torque of the steering wheel around the steering shaft, such as the frictional resistance torque of the steering wheel around the steering shaft and the contact surface between the steering wheel and the steering wheel, causing the steering The wheel rotates around the steering shaft of the wheel.
- a deflection moment T bias around the steering axis of the steering wheel is set. This moment generates a corresponding torque that makes the wheel reach a stable state when the wheel deviates to a desired position to form a stable steering.
- the torque required for the steering wheel is opposite to the direction of rotation of the wheel, it can also be provided by the braking system.
- T- deflection refers to the torque with the following characteristics: when the wheel is not deflected, the magnitude is 0, and it can change accordingly with the change of the wheel deflection angle; when the wheel is in the deflection state, the deflection torque can follow the wheel deflection angle The size changes accordingly, and the direction of the rotational torque is always opposite when the wheel is deflected.
- this moment will cause the wheel to have a tendency to return to the positive direction, that is, this moment will always be opposite to the direction of T spin when the wheel is deflected.
- the steering wheel directly receives the torque required for steering generated by the driving power source, and the forward or backward driving force of each wheel is used as the power source for steering, so that the steering wheel and the contact surface are generated
- the driving force thus achieves the effect of steering, there is no complicated steering gear and steering transmission mechanism, the structure is simple and does not take up a lot of space.
- the invention realizes vehicle steering in a low-cost, simple, robust and sensitive way; in particular, through the control of the different driving forces of each wheel, the deflection angle of each steering wheel can be individually controlled to better meet the overall requirements of the vehicle. Turn to demand.
- At least one deformable deflection control element is arranged between at least one connection point B and the vehicle body.
- the deflection control element When the wheel is pointing straight ahead, the deflection control element is in a free state, and no tension or pressure is generated. When the force is applied, the wheel deflects.
- the deflection control element When the deflection control element is stretched to generate a tensile force F pull or/and compressed to generate a pressure F pressure , the steering wheel is controlled to rotate around the steering shaft of the wheel.
- the deflection control element is stretched to generate a tensile force F pull controls the steering wheel to rotate around the wheel steering axis, or the deflection control element is compressed to generate pressure F pressure controls the steering wheel to rotate around the wheel steering axis, or it can be stretched to generate a tensile force F pulls at the same time applying a compressive force and F pressure controls the steering wheel to rotate around the wheel steering shaft.
- connection point B first take a connection point B and a deflection control element as an example.
- At least one point B is introduced as the point of action for generating the T- bias force.
- OAB is a rigid body that can only rotate around the wheel steering shaft (king pin) at point A.
- Design at least one deflection control element that can produce deformation between point B and point C on the body: when the wheel is pointing straight ahead, the deflection control element is in a free state, and no tension or pressure is generated.
- the deflection control members to be compressed, the pressure generated force F, which is generated when the steering wheel about the axis (kingpin) of the torque and a spin torque, T, T drag torque resistance balance
- the wheel can maintain a stable deflection angle; when the driving torque T drive is canceled or reduced, the driving force F and T spin will disappear or decrease, and the wheel will return to normal under the F pressure .
- connection points B are points B1 and B2 respectively. Points B1 and B2 are connected to point A respectively.
- the connection points OA, AB1 and AB2 are set as rigid bodies. Deflection control elements are set on the points to achieve deformation. When the wheel is pointing straight ahead, multiple deflection control elements are in a free state, and no pulling force or pressure is generated. When the wheel is deflected by applying force, multiple deflection the control member is stretched and a tensile force F to pull / pressure or compression force F is generated, controls the steering wheel about the steering wheel shaft, such a process scheme may provide another implementation possible. And the stability is relatively strong.
- Active control T deviation can be achieved by actively changing the state of the deflection control element in response to the steering demand, such as changing the stiffness of the deflection control element through an electronic control device, or changing the length of the deflection control element through an electronic control structure to indirectly generate the torque T deviation . So that the wheels are maintained at a stable deflection angle.
- the active deflection control element can provide the centering torque, or it can automatically return to the center by adjusting the size and direction of the driving torque of the steering wheel. (Figure 11 is an example).
- One of the embodiments is to use an active air spring to make the deflection control element.
- the air compressor 25 can inflate or pump air into the air chamber 27, and the air chamber 27 will cause the overall stiffness of the deflection control element 26 due to the increase or decrease of the internal gas. Raise or lower to achieve rigidity control of the deflection control element.
- the stiffness change of the deflection control element will affect the steering response characteristics: when the stiffness of the deflection control element becomes smaller, the same driving torque can make the steering wheel deflect faster and achieve a larger deflection angle; otherwise, the deflection of the steering wheel will It will slow down and the deflection angle will be smaller.
- the wheel still has a certain resistance f when there is no driving torque, and it is only used as a driven wheel to roll forward.
- a small amount of compression of the deflection control element is still required to balance the rotational torque generated by this resistance.
- the resistance f when the wheels are pointing straight ahead can be tested through the actual vehicle, and the pressure generated by the small compression amount of the pre-designed deflection control element can be used to balance the resistance f when the wheels are running to ensure that the wheels go straight during driving. Similar to the above-mentioned influencing conditions, it does not conflict with the main principle and method of the present invention, and can be specifically considered and resolved in actual application development.
- a vehicle steering system that individually controls the deflection angle of the steering wheel by separately driving and controlling each wheel that needs to be steered controlled, including:
- the driving power source mentioned in the present invention includes a power source (such as a drive motor) that provides a torque consistent with the direction of rotation of the wheel, and also includes a power source that provides the direction of rotation of the wheel.
- Power source with opposite torque such as braking system
- At least one steering wheel used to receive the direct or indirect force of the distributed driving power source and generate driving force between the steering wheel and the contact surface;
- Control center used to calculate the direct or indirect force of the distributed driving power source, and calculate the rotational torque T spin generated by the driving force on the steering shaft of the steering wheel to overcome the relevant resistance torque, so that the steering wheel turns around the wheel steering shaft Rotate.
- the control center specifically refers to the vehicle electronic control unit (ECU) in the subsequent application examples.
- the vehicle steering system also includes a yaw control element to generate a yaw moment T yaw around the steering axis of the steering wheel. This moment generates a corresponding moment that makes the wheel reach a stable state when the wheel is deflected to the desired position to form a stable steering .
- the deflection moment generating device further includes:
- At least one deformable deflection control element is provided between the connection point B and the vehicle body.
- the deflection control element When the wheel is pointing straight ahead, the deflection control element is in a free state, and does not generate tension or pressure.
- deflection control element When the wheel is deflected by applying force, deflection control element is stretched or compressed to produce tensile force F pressing force F is generated, the control steering wheel about the steering wheel shaft.
- the deflection angle of each steering wheel can be individually controlled, and there is no need to establish a physical connection between the two steering wheels.
- this method can realize independent control of the deflection angle of each steering wheel according to the needs of the steering intention of the whole vehicle on various vehicles such as front-wheel steering, rear-wheel steering, and multi-axle, so as to achieve the least resistance or other required steering trajectories. .
- the steering method of the traveling mechanism of the present invention includes:
- the deflection angle of each steering wheel can be controlled separately, and there is no need to establish a physical connection between the two steering wheels,
- the steering center of the vehicle is on the extension line of the rear axle of the vehicle to achieve Ackerman steering.
- Each steering wheel controls the steering in the following way: the steering wheel is directly or indirectly applied to the steering wheel by the distributed driving power source, so that a driving force is generated between the steering wheel and the contact surface, and the driving force is applied to the steering shaft of the steering wheel.
- the rotation torque T spin is generated, and the related resistance torque is overcome, such as the steering wheel around the steering shaft and the friction resistance torque between the steering wheel and the contact surface, etc., causing the steering wheel to rotate around the wheel steering shaft.
- control center can calculate the overall dynamic balance of the vehicle, including at least one of the driving force, resistance, and centrifugal force, so that the vehicle reaches the desired state of motion.
- the active deflection control element is used, according to the input of the deflection angle and the vehicle motion state, the characteristic targets including the stiffness and the length required for the deflection torque generator are obtained.
- the following uses a four-wheel, front-axle steering vehicle as an example to describe the application of the steering method of the present invention to the entire vehicle.
- the steering centers of the wheels need to coincide at one point. Since the two wheels of the rear axle cannot deflect, the steering centers of the two rear wheels are on the extension line of the rear axle, and the steering centers of the two front wheels intersect at the same point on the extension line of the rear axle (as shown in Figure 1).
- the deflection angles of the left and right steering wheels are not consistent (the deflection angle of the inner wheel is greater than the deflection angle of the outer wheel), and the force and direction of the deflection control element are also not consistent.
- the driving force required to achieve this two-wheel deflection And the direction is also different: the inner steering wheel needs the ground to give the tire the driving force to the rear of the vehicle to achieve; for the outer steering wheel, it needs to apply forward driving force. Under normal circumstances, the combined force of the two steering wheels cannot balance with the resistance in the direction of the vehicle or provide the acceleration required by the vehicle.
- FIGS. 6A-6D below list four working conditions on flat roads.
- Fig. 6A illustrates the situation of forward turning left.
- F1, F2, F3, and F4 respectively represent the driving force or backward drag force of the ground to each wheel.
- Fig. 6B shows a case of turning left and reversing.
- Fig. 6C is the working condition of forward turning right, and
- Fig. 6D is the working condition of reverse turning right.
- the steering wheel provided by the present invention includes a tire body, a steering knuckle 4, an upper control arm 2, a lower control arm 7, and a yaw control element 8 (as shown in Figure 8);
- the tire body may include an in-wheel motor and a tire.
- the tire here mainly refers to a rubber part.
- One side of the tire body is provided with a steering knuckle 4, the upper end of the steering knuckle 4 is connected to one end of the upper control arm 2, and the lower end of the steering knuckle 4 is connected to one end of the lower control arm 7;
- One end of the deflection control element 8 is connected to the steering knuckle 4; the other end of the upper control arm 2, the other end of the lower control arm 7, and the other end of the deflection control element 8 are used to connect the vehicle Frame assembly 5.
- the driving force of the wheels can be used to promote the steering of the vehicle, which can make the steering of the vehicle more convenient and faster and save costs.
- the steering wheel provided by the present invention further includes a first ball head 3 and a second ball head 10;
- the upper end of the steering knuckle 4 is connected to the upper control arm 2 through the first ball head 3; the lower end of the steering knuckle 4 is connected to the lower control arm 7 through the second ball head 10.
- the present invention also includes a third ball head 9 and a fourth ball head 6;
- One end of the deflection control element 8 is connected to the side end of the steering knuckle 4 through the third ball head 9, and the other end is used to connect to the frame assembly 5 through the fourth ball head 6.
- the tire body includes an in-wheel motor 12 and a tire 11; the in-wheel motor 12 is arranged in the inner cavity of the tire 11;
- the in-wheel motor 12 is connected to the steering knuckle 4 through a connecting shaft.
- the line connecting the centers of the first ball head 3 and the second ball head 10 is the main axis of the deflection of the tire body, ie.
- point B is introduced as the point of action for generating the T- bias force
- OAB is a rigid body that can only rotate around the wheel steering axis at point A, that is, the kingpin.
- the deflection control element 8 is designed between point B and point C on the vehicle body;
- the deflection control element 8 When the tire body points straight forward and the torque of the in-wheel motor 12 is less than the preset torque threshold, the deflection control element 8 is in a free state; no tension or pressure is generated.
- This torque threshold will be affected by factors such as tire size, vehicle weight, and steering knuckle size.
- the deflection control element 8 includes a first elastic member and a second elastic member
- One end of the first elastic member and the second elastic member is connected to the steering knuckle 4; one end of the first elastic member and the second elastic member is used to connect to the frame assembly 5;
- the first elastic member and the second elastic member are arranged on both sides of the steering knuckle 4 and are symmetrically distributed around the steering knuckle 4. When the first elastic member and the second elastic member are compressed, pressure is generated, and when the first elastic member and the second elastic member are stretched, no tensile force is generated.
- the function of a single deflection control element 8 can also be realized by the cooperation of the first elastic member and the second elastic member.
- the deflection angle of each steering wheel can be individually controlled, and there is no need to establish a physical connection between the two steering wheels.
- the present invention can realize independent control of the deflection angle of each steering wheel according to the needs of the steering intention of the whole vehicle on various vehicles such as front-wheel steering, rear-wheel steering, and multi-axle, so as to achieve minimum resistance or other requirements. Turn to track.
- the vehicle provided in the present invention includes the steering wheel in the above embodiment, and also includes a rear wheel body, a tie rod 20, a rear upper control arm 21, a rear lower control arm 22, and a frame assembly 5;
- the steering wheel is arranged at the front end of the frame assembly 5, and the steering wheel is connected to the frame assembly 5 through the deflection control element 8, the upper control arm 2, and the lower control arm 7;
- the rear wheel body is arranged at the rear end of the frame assembly 5, and the rear wheel body is connected to the frame assembly 5 through a tie rod 20, a rear upper control arm 21, and a rear lower control arm 22.
- the upper control arm 2 and the lower control arm 7 of the steering wheel are connected to the frame assembly 5 through the axle pin 1.
- the steering centers of the wheels need to coincide at one point. Since the two wheels of the rear axle cannot be deflected, the steering centers of the two rear wheels are on the extension line of the rear axle, and the steering centers of the left steering wheels of the two front wheels intersect at the same point on the extension line of the rear axle, as shown in Figure 6. . At this time, the deflection angles of the left and right steering wheels are inconsistent, that is, the deflection angle of the left steering wheel is greater than the deflection angle of the right steering wheel, and the force and direction of the deflection control element 8 are also inconsistent.
- the left steering wheel requires the ground to give the tires to the rear of the vehicle to achieve the driving force; for the right steering wheel, forward driving force is required.
- the combined force of the two steering wheels cannot balance with the resistance in the direction of the vehicle or provide the acceleration required by the vehicle.
- Figure 6 illustrates one of these situations.
- F1, F2, F3, and F4 respectively represent the driving force or backward drag force of the ground to each wheel.
- the right front suspension and the left front suspension are completely symmetrical in design, so they also have a steering function.
- the suspension of the two rear wheels in this embodiment also adopts a double-wishbone independent suspension.
- the difference from the front suspension is that the deflection control element 8 is replaced by the tie rod 20 with an invariable length. In this way, when a forward or reverse driving torque is applied to the rear wheels, since the length of the tie rod 20 is immutable, the rear wheels cannot rotate around their kingpins, so that they can only roll forward or rearward of the vehicle.
- the purpose of the front wheel steering is
- the vehicle steering method provided by the present invention is used to control the steering of the steering wheel.
- the steering wheel includes at least a tire body and a deflection control element.
- the tire body is connected to the frame assembly through the deflection control element 8. 5. Including the following steps (Figure 10 is only an implementation flow chart):
- Step S1 Obtain a steering instruction
- Step S2 Calculate the yaw angle of each steering wheel according to the steering command, and then calculate a steering torque of each wheel and issue a corresponding control command.
- the steering wheel deflects under this torque, and the vehicle turns;
- Step S3 Obtain the steering end command, recalculate the torque required by each wheel when going straight, and issue a control command to keep the wheel deflection torque no longer present, the wheels return to the center, and the vehicle goes straight.
- the electronic control unit when the vehicle is started, the electronic control unit (ECU) first confirms whether it has received a steering request and a vehicle speed request from a human driver or an unmanned driving system. If a steering-related instruction is received, the ECU will first Calculate the required deflection angle of the left steering wheel 15 and the right steering wheel 16;
- the secondary steered wheels are the left rear wheel 17 and the right rear wheel 18, and may also be other non-steered wheels in the modified example.
- ECU calculates the torque of each wheel according to the dynamic balance of the whole vehicle; and then controls the motor of each wheel according to the calculation result.
- the vehicle can achieve stable steering.
- the ECU When an updated steering command is sent, the ECU will recalculate the torque distribution based on the steering command and the vehicle speed command, and the vehicle will start a new steering condition. Until the ECU receives the instruction of the vehicle to go straight, the ECU will redistribute torque to the four wheels to start driving straight.
- the present invention utilizes the feature that the torque of each wheel of a distributed drive vehicle can be independently controlled, instead of using a dedicated steering motor or a human driver as the power source for steering, it uses the forward or backward driving of each wheel.
- vehicle steering can be realized in a low-cost, simple and robust manner; the present invention can individually control the deflection angle of each steering wheel without establishing a physical connection between the two steering wheels;
- the overall steering movement, through the control of the different driving forces of each wheel, is more convenient to meet the overall steering, speed, and acceleration requirements of the vehicle; in the present invention, the deflection control element can be used to promote the steering of the vehicle through the driving force of the wheels, which can make the vehicle The steering is more convenient and quicker and saves costs.
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Abstract
一种车用转向方法、***、行驶机构的转向方法,其方法包括:转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩,使得转向轮与接触面之间产生驱动力,驱动力对转向轮的转向轴产生旋转力矩T 旋,并且克服相关的阻力矩,如转向轮绕转向轴及转向轮与接触面的摩擦阻力矩等,引起所述转向轮绕车轮转向轴转动。并且,设置一个绕转向轮的转向轴的偏转力矩T 偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。本申请的转向轮直接接受驱动动力源产生要求转向的力矩,使得转向轮与接触面之间产生驱动力(向前或向后),驱动力作为转向的动力来源从而达到转向的功效,结构简单且不占用大量的空间。
Description
本发明涉及车辆转向原理,具体地,特别涉及一种车用转向方法、车用转向***及包含车用转向***的行驶机构。
目前常见车用转向***主要有三类:一类为传统的汽车转向***,其由转向操纵机构、转向器和转向传动机构三大部分组成。一般还需要液压或电动的转向助力或动力***,以实现转向助力或自动控制。请参阅图1,当汽车转向时,驾驶员对转向操纵机构施加一个转向力矩,经转向器传递到转向传动机构,控制转向车轮偏转。第二类为差速转向,其车轮无法实现偏转,车辆通过分别控制左右两侧驱动轮的转速实现转向。常用在履带式车辆或其他轮式特种车辆上。第三类为舵机转向***,各车轮配备独立的转向舵机,通过舵机控制车轮的偏转可以实现各个车轮相互独立的偏转角度。还有一些其他非常见的转向***,如麦克纳姆轮转向***等。
目前现有的转向形式存在着下述缺陷:
第一,第一类的行驶机构转向方法存在以下的缺陷。
首先,传统行驶机构(比如,汽车)由于需要将驱动和转向两种运动进行解耦控制,因此需要一套独立的、复杂的转向***,包括转向操纵机构、转向器和转向传动机构;一般还需要液压或电动的转向助力或动力***,以实现转向助力或自动控制。特别是,现有转向体系中包括复杂的转向传动机构,不仅精度要求高,而且结构极其复杂。由此导致整个研发难度大,成本较高。另外,由于独立的转向***结构复杂,占用较大车辆内部空间,一般安装在车体下方,使得汽车离地高度受限,同时也影响在一些特殊车体的设计或应用场合的应用。比如,给老人或残疾人设计的行驶机构,由于车用转向***安装在车体下方,结构复杂,占用空间大,其高度也无法做得小,很影响老人或残疾人的使用舒适度。
其次,随着汽车设计对空间要求的提高,目前已经有分布式驱动用于车辆设计以提高空间效率,比如四轮采用轮毂电机的汽车。但是此类车辆的转向***仍然是传统的转 向***,需通过转向操纵机构施加一个转向力矩,经转向器传递到转向传动机构,控制转向车轮偏转。转向的动力源仍然为人类驾驶员或专门的转向电机。
第二类的行驶机构转向方法存在以下的缺陷是:差速转向***通过控制两侧车轮的转速使得车身转向,这就导致车轮产生较大的侧向滑动,轮胎的磨损严重,阻力较大,对动力***及车辆要求较高。
第三类的行驶机构转向方法存在以下的缺陷是:舵机转向***由于每个车轮都配有专门的转向舵机,导致***复杂,占用空间大,成本也较高。
发明内容
针对现有技术中的缺陷,本发明的第一目的是提供一种车用转向方法和车用转向***。
针对现有技术中的缺陷,本发明的第二目的是提供一种行驶机构的转向方法及行驶机构。
一种车用转向方法,用以车轮进行分布式驱动控制,包括:转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩,转向轮与接触面之间产生反方向的驱动力,所述驱动力对转向轮的转向轴产生旋转力矩T
旋,并且克服转向轮绕转向轴的摩擦阻力矩后,如转向轮绕转向轴及转向轮与接触面的摩擦阻力矩等,引起所述转向轮绕车轮转向轴转动。并且,还可以计算车辆整体动力学平衡,包含驱动力、阻力、离心力在内的至少其中之一因素,使车辆达到期望的运动状态。
其方法还包括:设置一个绕转向轮的转向轴的偏转力矩T
偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。
当车轮处于偏转状态时,偏转力矩可随着车轮偏转角度大小的变化而相应变化,且在车轮偏转时始终与旋转力矩的方向相反。或者
在车轮没有偏转到期望位置前,偏转力矩为任意允许车轮偏转的扭矩值;当车轮转到期望位置时,偏转力矩将设定为能维持车轮在此位置的扭矩。
选择至少一作为产生偏转力矩的力作用点B,设置连接处OA、AB为刚性体,O点为车轮的几何中心,A点为O点绕着车轮转向轴旋转的转动点,B点作为产生偏转力矩的力作用点,在至少一连接点B与车身之间设置一可产生变形的偏转控制元件,当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,偏转控制元件被拉伸产生拉力F
拉或/和被压缩产生压力F
压,控制转向 轮绕车轮转向轴转动。
与现有技术相比,本发明具有如下的有益效果:
1、本发明利用分布式驱动车辆各轮扭矩可独立控制的特点,不是利用专门的转向电机或人类驾驶员作为转向的动力来源,而是利用各个车轮的向前或向后驱动力作为转向的动力来源,以一种低成本、简单、稳健、灵敏的方式实现车辆转向;控制该力的大小即可利用使得转向轮与接触面之间产生驱动力,没有复杂的转向器和转向传动机构,结构简单且不占用大量的空间。
2、本发明通过对每个车轮不同驱动力的控制,可单独控制每个转向轮的偏转角度,更好的满足车辆整体的转向需求;
3、本发明的转向轮之间无需物理连接,有利于车辆模块化布置,将极大提升车辆的空间利用效率,缩短研发周期,节省研发成本。
通过阅读参照以下附图对非限制性实施例所作的详细描述,本发明的其它特征、目的和优点将会变得更明显:
图1为基于阿克曼理论的车辆转向示意图;
图2为本发明中单车轮受力分析的左视图;
图3为本发明中单车轮受力分析的俯视图;
图4为本发明中弹性元件受力的俯视图;
图5为本发明中弹性元件受力的另一方向的俯视图;
图6A-图6D为本发明中整车转向示意图;
图7为本发明中转向轮的结构示意图;
图8为本发明中转向***整车结构示意图;
图9为本发明变形例中弹性元件的示意图;
图10为本发明中车用转向方法的流程图;
图11为采用主动式空气弹簧制作偏转控制元件的示例图。
图中:1为轴销;2为上控制臂;3为第一球头;4为转向节;5为车架总成;6为第四球头;7为下控制臂;8为偏转控制元件;9为第三球头;10为第二球头;11为车胎;12为轮毂电机;13为左转向轮的偏转控制元件,14为右转向轮的偏转控制元件,15为左转向轮;16为右转向轮;17为左后轮本体;18为右后轮本体;19为电子控制 单元;20为拉杆;21为后上控制臂;22为后下控制臂;23为第一弹性件;24为第二弹性件25为空气压缩机;26为偏转控制元件;27为气室。
下面结合具体实施例对本发明进行详细说明。以下实施例将有助于本领域的技术人员进一步理解本发明,但不以任何形式限制本发明。应当指出的是,对本领域的普通技术人员来说,在不脱离本发明构思的前提下,还可以做出若干变形和改进。这些都属于本发明的保护范围。
首先需要说明的是行驶机构包括各种能使物体产生移动或位移的装置,其包括且不限于各种轮式或履带式的机构,转向机构包括以控制各类轮式或履带式车辆的行驶方向以实现行驶方向与原有既行方向有所不同的机构。
在本实施例中,本发明同样基于阿克曼理论。依据阿克曼转向几何设计的车辆,沿着弯道转弯时,使四个轮子路径的圆心大致上交会于后轴的延长线上,让车辆可以顺畅的转弯,如图1所示。
对于车辆来说,若要实现车轮的偏转,必须施加一个绕车轮转向轴的力矩,即绕车轮主销的力矩。传统汽车转向***通过转向传动机构对车轮转向节施加转向力,从而产生让车轮偏转的力矩。本发明结合分布式驱动各轮可独立控制驱动力矩的特点,提出了一种新的转向力矩来源与转向方式,由转向轮的驱动力带动车轮偏转。
以下首先以单个车轮为例来进行说明,过程中对车辆动力学因素进行了简化,如未考虑轮胎的侧向力、未考虑主销倾角、未考虑轮胎变形等,在实际开发应用中可基于简化模型增加考虑各相关参数的平衡设计。具体描述如下:当分布式动力源向车轮施加逆时针的力矩T
驱时(如图2左视图),接触面将给车轮一向左侧的驱动力F。在右侧的俯视图中,车轮绕过A点的竖直方向的车轮转向轴(主销)偏转。地面给轮胎的驱动力F会对车轮转向轴(主销)产生一个旋转力矩T
旋,当此力矩足以克服***绕车轮转向轴(主销)的阻力矩T
阻时,车轮将会绕车轮转向轴(主销)转动。通过控制驱动力矩T
驱的大小即可控制驱动力F的大小,从而间接控制转向力矩T
旋的大小。当T
旋大于T
阻时,如果***没有其他绕车轮转向轴(主销)的力矩,车轮将发生持续偏转,直到机械位置的极限。为了能稳定的控制车轮偏转程度,需要引入一个新的绕车轮转向轴(主销)的力矩T
偏,此力矩需要在车轮偏转到期望位置时能产生大小合适的力矩,可以使车轮达到稳定状态,从而维持在该角度,形 成稳定的转向。
我们后续提及的车用转向的车可以是包含了4轮或多轮匹配扭矩以实现期望的行驶的装置,包括无人驾驶车、有人驾驶车等具有行驶功能的工具,也可以是仿真或具有相似功能的玩具、模型等。当然,本实例也可以应用于具有可移动的以轮式或借助部分轮式来完成移动功能的装置或***。
在本发明中提及的驱动动力源包括提供与车轮旋转方向一致的力矩的动力源(如驱动电机),也包括提供与车轮旋转方向相反的力矩的动力源(如制动***)。
一种车用转向方法,用以对车轮进行分布式驱动控制,包括:转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩,使得转向轮与接触面之间产生驱动力,所述驱动力对转向轮的转向轴产生旋转力矩T
旋,并且克服转向轮绕转向轴的摩擦阻力矩后,如转向轮绕转向轴及转向轮与接触面的摩擦阻力矩等,引起所述转向轮绕车轮转向轴转动。设置一个绕转向轮的转向轴的偏转力矩T
偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。
当转向轮所需力矩与车轮旋转方向相反时,也可以由制动***提供。
实现此力矩的方式又可以分为主动式和被动式两种。被动式控制的T
偏指具有以下特点的力矩:在车轮没有偏转时大小为0,并可随着车轮偏转角度大小的变化而相应变化;当车轮处于偏转状态时,偏转力矩可随着车轮偏转角度大小的变化而相应变化,且在车轮偏转时始终与旋转力矩的方向相反。一般来说,此力矩将促使车轮产生回正趋势,也即此力矩在车轮偏转时始终与T
旋的方向相反。主动式控制的T
偏指具有以下特点的力矩:在车轮没有偏转到期望位置前,偏转力矩,T
偏为任意允许车轮偏转的扭矩值;当车轮转到期望位置时,偏转力矩T
偏将设定为能维持车轮在此位置的扭矩。
本发明可以没有传统车辆的独立转向机构,转向轮直接接受驱动动力源产生的要求转向的力矩,各个车轮的向前或向后驱动力作为转向的动力来源,使得转向轮与接触面之间产生驱动力从而达到转向的功效,没有复杂的转向器和转向传动机构,结构简单且不占用大量的空间。本发明以一种低成本、简单、稳健、灵敏的方式实现车辆转向;特别是通过对每个车轮不同驱动力的控制,可单独控制每个转向轮的偏转角度,更好的满足车辆整体的转向需求。
实施例一
以下以被动式控制T
偏的一种实现方式为例进行介绍:
选择至少一作为产生偏转力矩的力作用点B,设置连接处OA、AB为刚性体,O点为车轮的几何中心,A点为O点绕着车轮转向轴旋转的转动点,B点作为产生偏转力矩的力作用点,
在至少一连接点B与车身之间设置至少一可产生变形的偏转控制元件,当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,偏转控制元件被拉伸产生拉力F
拉或/和被压缩产生压力F
压,控制转向轮绕车轮转向轴转动。连接点B可以有多个,同样可产生变形的偏转控制元件也可以有多个。即,偏转控制元件被拉伸产生拉力F
拉控制转向轮绕车轮转向轴转动,也可以是偏转控制元件被压缩产生压力F
压控制转向轮绕车轮转向轴转动,也可以是被拉伸产生拉力F
拉同时施加以压缩力F
压控制转向轮绕车轮转向轴转动。
在本实例中,先以一个连接点B、一个偏转控制元件为例。
引入至少一B点作为产生T
偏的力的作用点,OAB为刚性体,只能绕过A点的车轮转向轴(主销)旋转。在B点与车身上的C点之间设计至少一可产生变形的偏转控制元件:当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力。
当车轮向右偏转时(如图4所示),偏转控制元件将被拉伸,产生拉力F
拉,当其产生的绕车轮转向轴(主销)的力矩与力矩T
旋、阻力矩T
阻平衡时车轮即可维持稳定的偏转角度;若此时取消或减小驱动力矩T
驱,F与T
旋将消失或减小,绕主销形成的力矩将不再平衡,车轮将在拉力F
拉的带动下回正。当车轮向左偏转时(如图5所示),偏转控制元件将被压缩,产生压力F
压,当其产生的绕车轮转向轴(主销)的力矩与力矩T
旋、阻力矩T
阻平衡时车轮即可维持稳定的偏转角度;当取消或减小驱动力矩T
驱,驱动力F与T
旋将消失或减小,车轮将在F
压带动下回正。
车轮偏转稳定时的力矩平衡方程为:T
旋=T
阻+T
偏
车轮向右转向时有下式成立:F×OA=T
阻+F
拉×L
1;车轮向左转向时有下式成立:F×OA=T
阻+F
压×L
2。
连接点可以是多个,比如以图9为例,连接点B分别为B1、B2点,B1、B2点分别与A点连接,设置连接处OA、AB1、AB2为刚性体,在B1、B2点上分别设置偏转控制元件,来实现可产生变形,当车轮指向正前方时,多个偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,多个偏转控制元件被拉伸产生拉力F
拉和/或被压缩产生压力F
压,控制转向轮绕车轮转向轴转动,这种处理方案可 以提供另一种实现可能。并且稳定性也比较强。
实施例二
以下以主动式控制T
偏的一种实现方式为例进行介绍:
主动式控制T
偏可对应转向需求通过主动改变偏转控制元件的状态实现,比如通过电控装置改变偏转控制元件的刚度,或是通过电控结构改变偏转控制元件的长度从而间接产生力矩T
偏,从而使车轮维持在稳定的偏转角度。当车轮需要回正时,可以由主动式偏转控制元件提供回正力矩,也可通过调整转向轮的驱动力矩大小和方向使其自动回正。(图11为例)。其中一种实施例为采用主动式空气弹簧制作偏转控制元件,空气压缩机25可以向气室27充气或抽气,气室27将因为内部气体的增加或减少而引起偏转控制元件26整体的刚度升高或降低,从而实现对偏转控制元件的刚度控制。偏转控制元件的刚度变化则会影响转向响应特性:当偏转控制元件的刚度变小,同样的驱动力矩可以让转向轮更快的偏转,并达到更大的偏转角度;反之,转向轮的偏转将会变慢,偏转角度也会更小。
在实际情况下,还需考虑一些复杂的影响工况。如:车轮在没有驱动力矩,只作为从动轮向正前方做滚动运动时仍然有一定的阻力f。此时仍然需要偏转控制元件有一微小的压缩量以平衡此阻力产生的旋转力矩。为此可以通过实车测试出车轮指向正前方行驶时的阻力f,通过预先设计偏转控制元件的微小压缩量产生的压力平衡掉车轮行驶时的阻力f,以保证车轮在行驶过程中直行。类似以上这种影响工况,与本发明的主体原理与方法不冲突,可在实际应用开发中予以具体考虑解决。
一种车用转向***,通过对每个需要控制转向的车轮进行分别驱动控制,单独控制所述转向轮的偏转角度,包括:
分布式驱动动力源:用于为转向车轮提供转向的力,本发明中提及的驱动动力源包括提供与车轮旋转方向一致的力矩的动力源(如驱动电机),也包括提供与车轮旋转方向相反的力矩的动力源(如制动***);
至少一转向轮:用于接受分布式驱动动力源直接或间接的作用力,并在所述的转向轮与接触面之间产生驱动力;
控制中心:用于计算分布式驱动动力源直接或间接作用力的大小,并计算驱动力对转向轮的转向轴产生的旋转力矩T
旋,以克服相关的阻力矩,使得转向轮绕车轮转向轴转动。控制中心在后续的应用例中特别指的是车辆电子控制单元(ECU)。
车用转向***还包括偏转控制元件,用以产生一个绕转向轮的转向轴的偏转力矩 T
偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。
偏转力矩产生装置进一步包括:
选择至少一作为产生偏转力矩的力作用点B,设置连接处OA、AB为刚性体,O点为车轮的几何中心,A点为O点绕着车轮转向轴旋转的转动点,B点作为产生偏转力矩的力作用点,
在连接点B与车身之间设置至少一可产生变形的偏转控制元件,当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,偏转控制元件被拉伸产生拉力F
拉或被压缩产生压力F
压,控制转向轮绕车轮转向轴转动。
使用本发明所述的转向方法,可单独控制每个转向轮的偏转角度,且无需在两个转向轮间建立物理连接。对于车辆整体转向运动,通过对每个车轮不同驱动力的控制,满足车辆整体的转向、速度、加速度的需求。因此,此方法在前轮转向、后轮转向、多轴等多种车辆上均可根据整车转向意图的需要对各个转向轮实现偏转角度的单独控制,从而实现阻力最小或其他需要的转向轨迹。
综上所述,本发明行驶机构的转向方法,包括:
可单独控制每个转向轮的偏转角度,且无需在两个转向轮间建立物理连接,
对于车辆整体转向运动,通过对每个转向车轮不同驱动力的控制,使车辆的转向中心在车辆后轴的延长线上,实现阿克曼转向,
每一转向轮通过以下方式控制转向:转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩,使得转向轮与接触面之间产生驱动力,所述驱动力对转向轮的转向轴产生旋转力矩T
旋,并且克服相关的阻力矩,如转向轮绕转向轴及转向轮与接触面的摩擦阻力矩等,引起所述转向轮绕车轮转向轴转动。
本实例控制中心可以计算车辆整体动力学平衡,包含驱动力、阻力、离心力在内的至少其中之一因素,使车辆达到期望的运动状态。当采用主动式偏转控制元件时,根据偏转角度、车辆运动状态在内的输入,获得偏转力矩产生装置所需设定包括刚度、长度在内的特性目标。
以下以四轮、前轴转向车辆为例,对本发明所述的转向方式在整车上的应用进行说明。针对此种形式的车辆,为了使整个转向过程中的阻力最小,转向运动尽可能平顺,需要各轮的转向中心重合于一点。由于后轴两车轮不可以偏转,因此两后 轮的转向中心在后轴的延长线上,且两前轮的转向中心相交于后轴延长线的同一点(如图1所示)。此时左右两侧转向轮的偏转角大小不一致(内侧轮的偏转角大于外侧轮的偏转角),偏转控制元件的受力大小和方向也不一致,为实现此两轮偏转所需驱动力的大小和方向也就不同:内侧转向轮需要地面给轮胎指向车辆后方的驱动力才可以实现;对于外侧转向轮,则需施加向前的驱动力。通常情况下,两转向轮的合力并不能与车辆行驶方向的阻力平衡或提供车辆需要的加速度。为了使四轮驱动力的合力与整车前进的阻力平衡或提供车辆需要的加速度,就需要在后轴两轮上施加不同方向的驱动力矩或制动力矩进行匹配,以实现车辆按照期望的运动方式稳定前进。根据车辆动力学,综合考虑驱动力、阻力、侧向力、重力及路面因素等,通过车辆在纵向和横向的力平衡可求出各轮的驱动力分配。下图6A-6D列举了平坦路面下的四种工况。图6A列举了前进左向转弯的情况,图中F1、F2、F3、F4分别表示地面给各轮的驱动力或倒拖力。图6B为左转倒车的一种情况。图6C为前进右转的工况,图6D为倒车右转的工况。
应用例
基于上述原理论,在本发明的实施例中,本发明提供的转向轮,包括轮胎本体、转向节4、上控制臂2、下控制臂7以及偏转控制元件8(如图8所示);在本实例中轮胎本体可以包括轮毂电机和车胎,这里的车胎主要是指橡胶部分。
所述轮胎本体的一侧设置有转向节4,所述转向节4的上端连接所述上控制臂2的一端,所述转向节4的下端连接所述下控制臂7的一端;
所述偏转控制元件8的一端连接所述转向节4;所述上控制臂2的另一端、所述下控制臂7的另一端以及所述偏转控制元件8的另一端用于连接所述车架总成5。
在本实施例中,本发明中通过应用偏转控制元件,能够通过车轮驱动力促使车辆转向,能使车辆转向更方便快捷,节约成本。
在本发明一实施例中,本发明提供的转向轮,还包括第一球头3和第二球头10;
所述转向节4的上端通过所述第一球头3连接所述上控制臂2;所述转向节4的下端通过所述第二球头10连接所述下控制臂7。
本发明还包括第三球头9和第四球头6;
所述偏转控制元件8的一端通过所述第三球头9与所述转向节4的侧端相连,另一端用于通过所述第四球头6连接到车架总成5上。
所述轮胎本体包括轮毂电机12和车胎11;所述轮毂电机12设置在所述车胎11的 内腔中;
所述轮毂电机12通过连接轴与转向节4连接。
所述第一球头3和第二球头10的球心连线为所述轮胎本体偏转的主轴,即。
在本发明的一实施例中,引入B点作为产生T
偏的力的作用点,OAB为刚性体,只能绕过A点的车轮转向轴,即主销旋转。在B点与车身上的C点之间设计有所述偏转控制元件8;
当所述轮胎本体指向正前方时,所述轮毂电机12的扭矩小于预设置的扭矩阈值时,所述偏转控制元件8为自由状态;不产生拉力也不产生压力。此扭矩阈值会受到轮胎尺寸、车重、转向节尺寸等因素的影响。
当所述轮胎本体向右偏转时,如图4所示,所述轮毂电机12驱动所述轮胎本体向内侧偏转时,所述偏转控制元件8为拉伸状态,产生拉力F拉,当其产生的绕车轮转向轴的力矩与力矩T旋、阻力矩T
阻平衡时车轮即可维持稳定的偏转角度;若此时取消或减小驱动力矩T
驱,F与T旋将消失或减小,车轮将在拉力F
拉的带动下回正。
当所述轮胎本体向左偏转时,如图5所示,所述轮毂电机12驱动所述轮胎本体向外侧偏转时,所述偏转控制元件8为压缩状态;产生压力F
压,当其产生的绕车轮转向轴的力矩与力矩T
旋、阻力矩T
阻平衡时车轮即可维持稳定的偏转角度;当取消或减小驱动力矩T
驱,F与T
旋将消失或减小,车轮将在F
压带动下回正。
在变形例中,如图9所示,所述偏转控制元件8包括第一弹性件和第二弹性件;
所述第一弹性件、所述第二弹性件的一端连接所述转向节4;所述第一弹性件、所述第二弹性件的一端另一端用于连接所述车架总成5;
所述第一弹性件和所述第二弹性件设置在所述转向节4的两侧且以所述转向节4为中心对称分布。当所述第一弹性件和所述第二弹性件被压缩时产生压力,当所述第一弹性件和所述第二弹性件被拉伸时不产生拉力。通过第一弹性件和所述第二弹性件的配合同样能够实现单个偏转控制元件8的功能。
当使用本发明提供的转向轮时,可单独控制每个转向轮的偏转角度,且无需在两个转向轮间建立物理连接。对于车辆整体转向运动,通过对每个转向轮施加不同驱动力的进行控制,满足车辆整体的转向、速度、加速度的需求。因此,本发明能够在在前轮转向、后轮转向、多轴等多种车辆上均可根据整车转向意图的需要对各个转向轮实现偏转角度的单独控制,从而实现阻力最小或其他需要的转向轨迹。
在本发明实施例中,本发明中提供的车辆,包括上述实施例中的转向轮,还包括后 轮本体、拉杆20、后上控制臂21、后下控制臂22和车架总成5;
所述转向轮,设置于所述车架总成5的前端,所述转向轮通过所述偏转控制元件8、上控制臂2、下控制臂7与所述车架总成5连接;
所述后轮本体,设置于所述车架总成5的后端,所述后轮本体通过拉杆20、后上控制臂21、后下控制臂22连接所述车架总成5。
所述转向轮的上控制臂2、下控制臂7通过轴销1与所述车架总成5连接。
进一步对本发明所述的转向轮在整车上的应用进行说明。针对此种形式的车辆,为了使整个转向过程中的阻力最小,转向运动尽可能平顺,需要各轮的转向中心重合于一点。由于后轴两车轮不可以偏转,因此两后轮的转向中心在后轴的延长线上,且两前轮左侧转向轮的转向中心相交于后轴延长线的同一点,如图6所示。此时左右两侧转向轮的偏转角大小不一致,即左侧转向轮的偏转角大于右侧转向轮的偏转角,所述偏转控制元件8的受力大小和方向也不一致,为实现此两转向轮偏转所需驱动力的大小和方向也就不同:左侧转向轮需要地面给轮胎指向车辆后方的驱动力才可以实现;对于右侧转向轮,则需施加向前的驱动力。通常情况下,两转向轮的合力并不能与车辆行驶方向的阻力平衡或提供车辆需要的加速度。为了使四轮驱动力的合力与整车前进的阻力平衡或提供车辆需要的加速度,就需要在后轴两轮上施加不同方向的驱动力矩或制动力矩进行匹配,以实现车辆按照期望的运动方式稳定前进。如图6列举了其中的一种情况,图中F1、F2、F3、F4分别表示地面给各轮的驱动力或倒拖力。
右前悬架与左前悬架在设计上完全对称,因此也具备转向功能。本实施例中两后轮的悬架也采用双横臂式独立悬架,与前悬架不同的是所述偏转控制元件8被长度不可变的所述拉杆20所取代。这样当在后轮施加正向或反向的驱动力矩时,由于所述拉杆20的长度不可变,后轮将无法绕其主销旋转,从而只能向车辆正前方或后方滚动,实现了只有前轮转向的目的。
在本发明实施例中,本发明提供的车辆转向方法,用于控制转向轮的转向,所述转向轮至少包括轮胎本体和偏转控制元件,所述轮胎本体通过偏转控制元件8连接车架总成5,包括如下步骤(图10仅为一种实施流程图):
步骤S1:获取转向指令;
步骤S2:根据所述转向指令计算每一转向轮的偏转角度,进而计算各轮的一转向扭矩并发出相应的控制指令,转向轮在此扭矩下偏转,车辆转弯行驶;
步骤S3:获取转向结束指令,重新计算直行时各轮所需扭矩,并发出控制指令,维 持车轮偏转的扭矩不复存在,车轮回正,车辆直行。
具体为,在本实施例中,当车辆启动后电子控制单元(ECU)首先确认是否收到来自人类驾驶员或无人驾驶***的转向请求及车速请求,如果收到了转向相关指令,ECU将首先计算左转向轮15、右转向轮16所需的偏转角度;
在本实施例中,所述从转向轮为左侧后轮17和右侧后轮18,在变形例中也可以为其他非转向轮。
然后ECU再根据整车动力学平衡计算各轮扭矩;接着再根据计算结果对各轮的电机进行控制。
在此种扭矩分配下,车辆即可实现稳定的转向。
当有更新的转向指令发送过来时,ECU将重新根据转向指令和车速指令计算扭矩分配,车辆也将开始新的转向工况。直到ECU收到车辆直行的指令后,ECU将重新给四个车轮分配扭矩,以开始直线行驶。
在本实施例中,本发明利用分布式驱动车辆各轮扭矩可独立控制的特点,不是利用专门的转向电机或人类驾驶员作为转向的动力来源,而是利用各个车轮的向前或向后驱动力作为转向的动力来源,以一种低成本、简单、稳健的方式实现车辆转向;本发明可单独控制每个转向轮的偏转角度,且无需在两个转向轮间建立物理连接;对于车辆的整体转向运动,通过对每个车轮不同驱动力的控制,更方便满足车辆整体的转向、速度、加速度的需求;本发明中通过应用偏转控制元件,能够通过车轮驱动力促使车辆转向,能使车辆转向更方便快捷,节约成本。
以上对本发明的具体实施例进行了描述。需要理解的是,本发明并不局限于上述特定实施方式,本领域技术人员可以在权利要求的范围内做出各种变形或修改,这并不影响本发明的实质内容。
Claims (25)
- 一种车用转向方法,其特征在于,用以对车轮进行分布式驱动控制,包括:转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩,使得转向轮与接触面之间产生驱动力,所述驱动力对转向轮的转向轴产生旋转力矩T 旋,并且克服转向轮与转向轴、转向轮与接触面的摩擦阻力矩后,引起所述转向轮绕车轮转向轴转动。
- 如权利要求1所述的车用转向方法,其特征在于,包括:设置一个绕转向轮的转向轴的偏转力矩T 偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。
- 如权利要求2所述的车用转向方法,其特征在于,包括:当车轮处于偏转状态时,偏转力矩可随着车轮偏转角度大小的变化而相应变化,且在车轮偏转时始终与旋转力矩的方向相反。
- 如权利要求2所述的车用转向方法,其特征在于,包括:在车轮没有偏转到期望位置前,偏转力矩为任意允许车轮偏转的扭矩值;当车轮转到期望位置时,偏转力矩将设定为能维持车轮在此位置的扭矩。
- 如权利要求2至4中任意一项所述的车用转向方法,其特征在于,包括:选择至少一作为产生偏转力矩的力作用点B,设置连接处OA、AB为刚性体,O点为车轮的几何中心,A点为O点绕着车轮转向轴旋转的转动点,B点作为产生偏转力矩的力作用点,在至少一连接点B与车身之间设置一可产生变形的偏转控制元件,当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,偏转控制元件被拉伸产生拉力F 拉和/或被压缩产生压力F 压,控制转向轮绕车轮转向轴转动。
- 如权利要求5所述的车用转向方法,其特征在于,偏转控制元件被拉伸产生拉力F 拉,产生绕车轮转向轴的偏转稳定力矩T 偏,其与旋转力矩T 旋、阻力矩T 阻平衡时,转向轮可维持稳定的偏转角度;若取消或减小驱动力矩T 驱,驱动力F与旋转力矩T 旋将消失或减小,绕转向轴形成的力矩将不再平衡,车轮将在拉力F 拉的带动下回正。
- 如权利要求5或6所述的车用转向方法,其特征在于,包括:偏转控制元件被压缩产生压力F 压,当其产生的绕车轮转向轴的偏转力矩T 偏与旋转 力矩T 旋、阻力矩T 阻平衡时车轮即可维持稳定的偏转角度;当取消或减小驱动力矩T 驱,驱动力F与T 旋将消失或减小,车轮将在F 压带动下回正。
- 如权利要求1所述的车用转向方法,其特征在于,包括:根据车辆动力学平衡,考虑整车驱动力、阻力、离心力在内的至少其中之一因素,并综合考虑转向需求,计算车辆各种运动状态下各车轮的驱动力,并实时向驱动力执行机构和/或制动力执行机构输出指令。
- 如权利要求4所述的车用转向方法,其特征在于,包括:通过电控装置改变偏转控制元件的刚度,或是通过电控结构改变偏转控制元件的长度从而间接产生力矩T 偏,从而使车轮维持在稳定的偏转角度,当车轮需要回正时,通过调整转向轮的驱动力矩使其自动回正,或由主动式偏转控制元件提供回正力矩。
- 如权利要求1所述的车用转向方法,其特征在于,包括:当转向轮所需力矩与车轮旋转方向相反时,可选择制动***提供或由转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩来实现转向。
- 一种车用转向***,其特征在于,通过对每个需要控制转向的车轮进行分别驱动控制,单独控制所述转向轮的偏转角度,包括:分布式驱动动力源:用于为转向车轮提供转向的力;至少一转向轮:用于接受分布式驱动动力源直接或间接的作用力,并在所述得转向轮与接触面之间产生驱动力;转向轮的转向轴:为转向轮的偏转提供旋转支撑;控制中心:用于计算分布式驱动动力源直接或间接作用力的大小,使得其产生的旋转力矩T 旋与偏转力矩T 偏、阻力矩T 阻平衡,实现转向轮的偏转;和/或计算车辆整体动力学平衡,包含驱动力、阻力、离心力在内的至少其中之一因素,使车辆达到期望的运动状态。
- 如权利要求11所述的车用转向***,其特征在于,还包括:偏转控制元件,用以产生一个绕转向轮的转向轴的偏转力矩T 偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。
- 如权利要求12所述的车用转向***,其特征在于,偏转力矩产生装置进一步包括:选择至少一作为产生偏转力矩的力作用点B,设置连接处OA、AB为刚性体,O点为 车轮的几何中心,A点为O点绕着车轮转向轴旋转的转动点,B点作为产生偏转力矩的力作用点,在连接点B与车身之间设置至少一可产生变形的偏转控制元件,当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,偏转控制元件被拉伸产生拉力F 拉或/和被压缩产生压力F 压,控制转向轮绕车轮转向轴转动。
- 如权利要求13所述的车用转向***,其特征在于,偏转控制元件进一步包括:在与OA的刚性体连接处分别设置多个AB刚性体,多个AB分别连接偏转控制元件。
- 如权利要求13所述的车用转向***,其特征在于,控制中心进一步包括:当采用主动式偏转控制元件时,根据偏转角度、车辆运动状态在内的输入,获得偏转力矩产生装置所需设定包括刚度、长度在内的特性目标。
- 一种行驶机构的转向方法,其特征在于,包括至少四轮在内的行驶机构匹配扭矩以实现设定的行驶方式:可单独控制每个转向轮的偏转角度,且无需在两个转向轮间建立物理连接,对于车辆整体转向运动,通过对转向车轮不同驱动力的控制,两后轮的转向中心在后轴的延长线上,且两前轮的转向中心相交于后轴延长线的同一点,转向轮通过以下方式控制转向:转向轮被分布式驱动动力源直接或间接单独施加转向所需力矩,使得转向轮与接触面之间产生驱动力,所述驱动力对转向轮的转向轴产生旋转力矩T 旋,并且克服转向轮与转向轴、转向轮与接触面的摩擦阻力矩后,,引起所述转向轮绕车轮转向轴转动,所述阻力矩包括转向轮绕转向轴及转向轮与接触面的摩擦阻力矩。
- 如权利要求16的行驶机构的转向方法,其特征在于,包括:当转向轮所需力矩与车轮旋转方向相反时,也可以由制动***提供。
- 如权利要求16的行驶机构的转向方法,其特征在于,包括:内侧转向轮需要接触面给转向轮指向车辆后方的驱动力;对于外侧转向轮,则需施加向前的驱动力。
- 如权利要求18的行驶机构的转向方法,其特征在于,包括:在后轴两轮上施加不同方向的驱动力矩或制动力矩进行匹配,以实现车辆按照期望的运动方式稳定前进。
- 如权利要求16的行驶机构的转向方法,其特征在于,包括:设置一个绕转 向轮的转向轴的偏转力矩T 偏,此力矩在车轮偏转到期望位置时产生使车轮达到稳定状态的相应力矩,以形成稳定的转向。
- 如权利要求20所述的车用转向方法,其特征在于,包括:当车轮处于偏转状态时,偏转力矩可随着车轮偏转角度大小的变化而相应变化,且在车轮偏转时始终与旋转力矩的方向相反。
- 如权利要求20所述的车用转向方法,其特征在于,包括:在车轮没有偏转到期望位置前,偏转力矩为任意允许车轮偏转的扭矩值;当车轮转到期望位置时,偏转力矩将设定为能维持车轮在此位置的扭矩。
- 如权利要求20至22中任意一项所述的车用转向方法,其特征在于,包括:选择至少一作为产生偏转力矩的力作用点B,设置连接处OA、AB为刚性体,O点为车轮的几何中心,A点为O点绕着车轮转向轴旋转的转动点,B点作为产生偏转力矩的力作用点,在至少一连接点B与车身之间设置一可产生变形的偏转控制元件,当车轮指向正前方时,偏转控制元件处于自由状态,不产生拉力也不产生压力,当车轮被施加力产生偏转时,偏转控制元件被拉伸产生拉力F 拉和/或被压缩产生压力F 压,控制转向轮绕车轮转向轴转动。
- 如权利要求16所述的车用转向方法,其特征在于,包括:根据车辆动力学平衡,考虑驱动力、阻力、离心力在内的至少其中之一因素,计算车辆各种运动状态下各车轮的驱动力,并实时向驱动力执行机构和/或制动力执行机构输出指令。
- 一种行驶机构,包括9至15所述的车用转向***。
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