CN116061699A

CN116061699A - Matrix vector running control technology for eight-wheel hub motor driven vehicle

Info

Publication number: CN116061699A
Application number: CN202111268702.4A
Authority: CN
Inventors: 廖自力; 马晓军; 蔡立春; 刘春光; 张运银; 袁东; 魏曙光; 李嘉麒; 朱宁龙; 杨恒程; 张茜; 杨茜; 疏歆; 高亭亮
Original assignee: Academy of Armored Forces of PLA
Current assignee: Academy of Armored Forces of PLA
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-05-05

Abstract

The invention provides a matrix vector running control method for a motor-driven wheeled vehicle, which comprises the following steps: constructing a plane motion model of the motor-driven wheeled vehicle, wherein the motion model outputs expected yaw rate and centroid slip angle; designing a whole vehicle controller based on the plane motion model; the vehicle controller comprises an upper controller and a lower controller; the upper controller is a yaw moment controller, which includes: the centroid slip angle control module receives the centroid slip angle as input and outputs moment required by centroid slip angle control; and a yaw rate control module that receives the centroid slip angle as an input and outputs a moment required for yaw rate control; the moment required by the centroid side deflection angle control and the moment required by the yaw rate control are controlled by a coordination control module to obtain a final output control quantity; the final output control amount is input to the lower controller to perform torque vector control and slip ratio control, thereby outputting a torque required for each wheel of the motor-driven wheeled vehicle, thereby controlling the motor-driven wheeled vehicle.

Description

Matrix vector running control technology for eight-wheel hub motor driven vehicle

Technical Field

The invention relates to a matrix vector running control technology of an eight-wheel hub motor-driven vehicle, in particular to a matrix vector running control method for a motor-driven wheeled vehicle.

Background

A multi-wheel off-road vehicle or a multi-wheel vehicle serving as a maneuvering task, such as an 8×8 distributed electrically-driven wheeled armored vehicle, adopts a full-wheel independent driving mode based on an in-wheel motor, and can realize different torque distribution modes among axles and wheels by randomly distributing the torque of each wheel within the performance range of the driving motor on the premise of meeting the running requirement of the vehicle. Compared with the traditional internal combustion engine wheeled vehicle, for example, each driving motor of the 8 x 8 distributed electric driving wheeled armored vehicle can be independently controlled and are not mutually influenced, so that the functions of braking anti-lock, driving anti-skid, yaw moment control, rollover prevention control and the like are realized more easily, and the vehicle has unique advantages in the aspects of enhancing the stability of the vehicle, improving the energy efficiency of the whole vehicle and the like. But also put forward higher requirement to the control strategy of traveling of whole car at the same time, namely how under different road conditions, operating mode, user demand, through the torque of a plurality of in-wheel motors of rational distribution, realize the control objective of traveling of vehicle to guarantee the stability of traveling of vehicle under the complicated operating mode.

The prior art has made a lot of researches on how to fully develop the advantages of distributed driving. One of the common methods is direct yaw moment control, namely, by tracking the yaw rate and the centroid side deviation angle, the yaw moment of the whole vehicle required by the stable running of the vehicle is obtained and distributed to each wheel. The control method mainly has two problems when applied to an electrically driven armored vehicle, namely, how to coordinate and control two variables of yaw rate and centroid slip angle by an upper layer controller, and how to effectively distribute torque from the whole vehicle to each wheel. There are other methods of target optimization such as a multivariable control method designed on the basis of yaw-rate tracking, a parallel control method based on single-input single-output yaw-rate and centroid slip angle, a torque distribution method with tire utilization as an optimization target, and the like, although attempts are made to improve the drivability and stability of the vehicle. However, these methods of target optimization have difficulty meeting the complex road conditions and driving requirements of wheeled off-road or armored vehicles, and thus have many limitations in practical applications.

The invention aims to solve the problems, and designs a control system and a control method for meeting the requirements of complex road conditions and multiple tasks so as to meet the application requirements of a wheeled electric drive vehicle.

Disclosure of Invention

In order to solve the problems existing in the prior art, the invention provides a matrix vector running control method for a motor-driven wheeled vehicle, which comprises the following steps: constructing a plane motion model of the motor-driven wheeled vehicle, wherein the motion model outputs expected yaw rate and centroid slip angle; designing a whole vehicle controller based on the plane motion model; the vehicle controller comprises an upper controller and a lower controller; the upper controller is a yaw moment controller, which includes: the centroid slip angle control module receives the centroid slip angle as input and outputs moment required by centroid slip angle control; and a yaw rate control module that receives the centroid slip angle as an input and outputs a moment required for yaw rate control; the moment required by the centroid side deflection angle control and the moment required by the yaw rate control are controlled by a coordination control module to obtain a final output control quantity; the final output control amount is input to the lower controller to perform torque vector control and slip ratio control, thereby outputting a torque required for each wheel of the motor-driven wheeled vehicle, thereby controlling the motor-driven wheeled vehicle.

Preferably, the lower controller includes a torque vector control module and a slip ratio control module, the torque vector control module takes the output of the yaw moment controller as input, outputs the motor torque of the driving wheel, and the motor torque of the driving wheel is modified by the slip ratio control module.

Preferably, the yaw rate control module includes a yaw rate slide film controller, and a slide film surface of the yaw rate slide film controller is:

wherein: s is(s) _γ A sliding mode variable for yaw rate control; c ₁ 、c ₂ Weights of yaw-rate error and rate of change, c ₁ ＞0，c ₂ More than 0, beta is the centroid slip angle, gamma is the yaw rate, gamma _d To the desired yaw rate, beta _d Is the desired centroid slip angle;

wherein P is an intermediate variable,

order the

Wherein ε is ₁ 、k ₁ The exponential approach law parameters are all larger than 0, and sgn is a sign function; there is then a number of such a method,

integrating the above to obtain yaw moment DeltaM required by yaw rate control _γ 。

Preferably, the centroid slip angle control module comprises a centroid slip angle synovial membrane controller, and a synovial membrane surface of the centroid slip angle controller is:

wherein: c ₃ 、c ₄ The weight of the centroid slip angle error and the change rate thereof are respectively; yaw moment control amount Δm of centroid slip angle _β Is that

Wherein: epsilon ₂ 、k ₂ An exponential approach law parameter; q is an intermediate variable which is used for the control of the temperature,

preferably, the coordination control module comprises a weighting function G, the yaw rate and the centroid slip angle are adjusted by the weighting function, and the final output control quantity delta M of the yaw moment controller is adjusted _z Is of the size of

ΔM _z ＝G·ΔM _γ +(1-G)ΔM _β

Wherein the weighting function is:

wherein: a. b is a threshold value controlled by adopting a centroid side piece angle respectively; when the centroid side deviation angle beta is less than or equal to a, only controlling the yaw rate; when the centroid side deflection angle a is more than beta and less than or equal to b, the centroid side deflection angle a and the centroid side deflection angle b are controlled in a combined way, and the larger the centroid side deflection angle is, the larger the weight of the centroid side deflection angle is; when the centroid side deflection angle beta is larger than b, only controlling the centroid side deflection angle; and the magnitude of the threshold values a and b can divide the control area according to the relation between the centroid slip angle and the tire lateral force, and then the final boundary value is determined through simulation experiments.

Preferably, the method further comprises: final output control quantity Δm for the yaw moment controller _z Synthesizing by using a torque vector method, wherein the synthesizing step comprises total driving force synthesis and yaw moment synthesis; the wheel torque of the motor-driven wheeled vehicle is divided into four groups by the shaft, and the longitudinal force F of the vehicle _xd And yaw moment M _z The size of (2) is:

wherein: f (F) _xij (i=1, 2,3,4 is the i-th axis, j=1, 2 is the left and right side) is the wheel longitudinal force; delta _xij (i=1, 2 is the i-th axis, j=1, 2 is the left and right sides) is the wheel angle; d is the wheelbase.

Preferably, the lower controller includes a torque vector control layer at which torque vector control including total driving force synthesis and yaw moment synthesis and slip ratio control are performed.

Preferably, the total driving force synthesis synthesizes the total driving force for forward movement of the vehicle according to the driver's demand and the vertical load ratio of the wheels.

Preferably, the yaw moment synthesis includes: Δm obtained by yaw moment controller _z The torque vectors of the front two shafts are synthesized according to the proportion, the yaw moment is not participated in by the rear two shafts, wherein the additional yaw moment is synthesized according to the proportion between the shafts, the addition and subtraction of the two wheels on the same axis are the same so as to maintain the total driving force unchanged, wherein

Wherein: Δfxij (i=1, 2 is the i-th axis, j=1, 2 is the left and right sides) is the wheel longitudinal force adjustment amount;

the final driving force can be obtained by adding the 8 wheel driving forces and the yaw moment adjustment amounts, respectively.

Preferably, the slip ratio control includes single wheel drive slip control and on-axis torque adjustment; the purpose of the slip control is to reduce drive torque setting; at the actual slip rate s and the desired slip rate s _d When the deviation e is large, the given torque is rapidly reduced; at s and s _d And when the deviation is smaller, eliminating a certain steady-state error.

Preferably, the anti-skid control adopts a PPI controller; p control is adopted when the error is large, and PI control is adopted when the error is small.

Drawings

Various embodiments or examples ("examples") of the present disclosure are disclosed in the following detailed description and drawings. The drawings are not necessarily drawn to scale. In general, the operations of the disclosed methods may be performed in any order, unless otherwise specified in the claims. In the accompanying drawings:

FIG. 1 illustrates a planar motion model of a distributed electrically driven vehicle according to the present invention;

FIG. 2 illustrates a vehicle control system for a distributed electrically driven vehicle in accordance with the present invention;

FIG. 3 is a graph of yaw efficiency versus steering radius for each axle drive wheel;

FIG. 4 is a block diagram of a torque vectoring controller according to the present invention;

FIG. 5 is a schematic diagram of a slip ratio controller according to the present invention;

FIG. 6 is a real-time simulation experiment platform for the present invention;

FIG. 7 is an experimental result of a simulation experiment of obstacle avoidance of a wheeled vehicle using the control system of the present invention;

fig. 8 is an experimental result of a skid resistance simulation experiment of a wheeled vehicle to which the control system of the present invention is applied.

Detailed Description

Before explaining one or more embodiments of the disclosure in detail, it is to be understood that the embodiments are not limited in their application to the details of construction and to the steps or methods set forth in the following description or illustrated in the drawings. The system and method of the present invention will be described in detail below with reference to the attached drawings.

1. Construction of plane motion model of wheeled vehicle

Assuming that the vehicle is operating in a linear region, the longitudinal speed is unchanged, the tire lateral force is proportional to the slip angle, and the influence of the running resistance is ignored. Neglecting the influences of a steering system and a suspension system, taking the longitudinal speed of the vehicle as a constant, and only considering lateral movement and yaw movement, and establishing a linear two-degree-of-freedom vehicle plane movement model, as shown in fig. 1. In FIG. 1, v is the vehicle speed, v _x 、v _y Longitudinal and lateral speeds of the vehicle, F _xi 、F _yi (i=1, 2,3,4 is the i-th axis) is the longitudinal and lateral forces of the wheel, respectively, L _i Representing the distance of the ith axis from the centroid of the vehicle, alpha _i Is the slip angle of the wheels, beta is the centroid slip angle, gamma is the yaw rate, delta ₁ And delta ₂ The steering angles of the wheels are the first axle and the second axle, O is the mass center of the vehicle, and O' is the steering center of the vehicle.

The relationship between the vehicle lateral acceleration and the lateral force satisfies the following relationship:

the yaw acceleration and yaw moment of the vehicle satisfy the following relationship

Wherein: m is the mass of the whole vehicle; i _z Is the moment of inertia about the centroid.

From the expressions (1) and (2), the desired yaw rate γ can be obtained _d And centroid slip angle beta _d Is that

Wherein: c (C) _i The cornering stiffness of the tires of each axle, a _s The rotation angle ratio of the front two axles is the rotation angle ratio of the front two axles; mu is the ground attachment coefficient; g is gravity acceleration;

l is the equivalent wheelbase, and the L is the equivalent wheelbase,

k is a stability coefficient, and the stability coefficient is the same as the stability coefficient,

2. design whole car controller

1. Method for determining vehicle control

For a vehicle running control system, the controller is a core part. The controller calculates the torque command of each driving motor according to the corresponding control strategy through analyzing the control signals of the driver and the motion state of the vehicle. The controller designed in the process is divided into two layers, namely an upper layer yaw moment controller and a lower layer torque vector controller, and the structure is shown in figure 2. In FIG. 2, ΔM _β Yaw moment, ΔM, required for centroid slip angle control _γ Required yaw moment for yaw rate control, deltaM _z The resulting total yaw moment is weighted. First, given a manipulation signal by a driver, a two-degree-of-freedom model of the vehicle obtains a desired yaw rate and a centroid slip angle of the vehicle according to the manipulation signal. And secondly, the upper layer yaw moment controller calculates the corresponding yaw moment respectively and coordinates the yaw moment and the yaw moment according to the weighting coefficient. And finally, the lower-layer torque vector controller distributes the yaw moment according to a torque vector synthesis method. Meanwhile, in order to avoid the situation that the wheel torque is too large and slip occurs, the output torque of the wheel is limited through a slip ratio controller.

2. Design yaw moment controller

The yaw moment controller has the function of solving the magnitude of the yaw moment required by the running of the vehicle, and the sliding mode control has the characteristics of good robustness, quick response, simple control, suitability for a nonlinear system and the like, so that the invention adopts a sliding mode control algorithm. After the two-degree-of-freedom model is additionally controlled by yaw moment, the differential equation is as follows

Designing a yaw rate sliding mode controller, and defining a sliding mode surface as

Wherein: s is(s) _γ A sliding mode variable for yaw rate control; c ₁ 、c ₂ Weights of yaw-rate error and rate of change, c ₁ ＞0，c ₂ ＞0.

Substituting the formula (7) into the formula (8) to obtain

Wherein P is an intermediate variable,

design of sliding mode control law by using exponential approach law, let

Wherein ε is ₁ 、k ₁ The exponential approach law parameters are all larger than 0, and sgn is a sign function. Typically, a system has serious buffeting when approaching rapidly, and k should be increased appropriately to weaken buffeting ₁ Is suitably reduced at the same time as epsilon ₁ Is combined with (9) to obtain

Integrating (11) to obtain yaw moment DeltaM required for yaw rate control _γ .

Designing a mass center slip-form controller, and defining a slip-form surface as

Wherein: c ₃ 、c ₄ The weight of the centroid slip angle error and the change rate thereof are respectively. The control law is designed by using the exponential approach law with reference to the yaw rate control, and the yaw moment control quantity delta M of the centroid slip angle can be obtained _β Is that

there is a complex coupling relationship between yaw rate and centroid slip angle. The invention is realized by setting a weighting functionAnd G, carrying out coordinated control on the number G and the number G. When the centroid side deviation angle of the vehicle is small, the gains of the yaw rate and the steering wheel angle can be used for representing the stability of the vehicle, and the vehicle can stably run only by controlling the yaw rate change. When the situation of tail flick, sideslip and the like occurs to the vehicle, the centroid sideslip angle of the vehicle is larger, and the centroid sideslip angle of the vehicle can be rapidly increased, and the influence of the tail flick and sideslip movement on the yaw rate of the vehicle body is smaller, so that the yaw rate under the working condition cannot well reflect the running state of the vehicle, and the movement of the vehicle can be effectively controlled through centroid sideslip angle control. Thus, both weighting functions are used for adjustment, and the final output control quantity DeltaM of the yaw moment controller _z Is of the size of

ΔM _z ＝G·ΔM _γ +(1-G)ΔM _β . (15)

In order to make the transition process smoother, a weighting function G is designed using a Z membership function (zmf), the expression of which is as follows:

wherein: a. b are thresholds respectively controlled by the centroid side piece angle. When the centroid side deflection angle is smaller than beta and less than or equal to a, only controlling the yaw rate; when the centroid side deflection angle a is more than beta and less than or equal to b, the centroid side deflection angle a and the centroid side deflection angle b are controlled in a combined way, and the larger the centroid side deflection angle is, the larger the weight of the centroid side deflection angle is; when the centroid slip angle beta is larger than b, only the centroid slip angle is controlled. The magnitude of the threshold values a and b can divide a control area according to the relation between the centroid slip angle and the tire lateral force, and then a final boundary value is determined through a simulation experiment.

3. Design torque vector controller

(1) Yaw efficacy analysis

Δm obtained by yaw moment controller _z Synthesized by a torque vector control method. Wheel torque is divided into 4 groups by axle. Because the thrust generated by the wheels is parallel to the ground, the resultant force generated by the wheels can only be parallel to the ground, and only the movement of the vehicle in the plane is considered. Longitudinal force F of vehicle _xd And yaw moment M _z Is of the size of

The equation set is an underdetermined equation set, and has infinite solutions, namely, the torque combination capable of realizing the control target has infinite solutions, and special solutions are required. The invention adopts a rule-based allocation method. For the simple yaw torque distribution problem, the simplest is the average distribution principle, that is, the driving torque adjustment amounts of the left and right driving wheels increased or decreased are the same, and the method is simple and direct, but fails to take the difference of the yaw actions of the driving wheels into consideration. Yaw torque is essentially the result of the action of tire forces. Due to the influence of factors such as vehicle structural characteristics and steering wheel angles, when different wheels apply the same driving moment or braking moment, the generated yaw moment is different, and the ratio of the yaw moment generated by the driving wheels to the driving moment of the driving wheels is defined as yaw efficiency. Yaw efficiency K of drive wheel i _i Can be expressed as

Wherein: t (T) _i For the torque output by the driving wheel i, T _i ＝F _i ·r，F _i R is the effective radius of the tire and is the longitudinal force of the tire; ΔM _i Is F _i The generated yaw moment about the center of the vehicle.

The tire force F generated by the yaw moment additionally applied to the tire is regarded as directly acting in the tire longitudinal direction. Obviously, when the same force F is applied to the non-steered wheels of the rear two axles (i=3, i=4) of the vehicle, the yaw moment generated by the non-steered wheels is the same and has the same magnitude

As shown in fig. 1, taking left steering as an example, the yaw moments generated by the front two-axis (i=1, i=2) steering wheels when the same force is applied to the front two-axis (i=1, i=2) steering wheels are respectively

The steering wheel angle and steering radius relationship thus obtained can be approximately expressed as

Wherein: r is the turning radius.

Combining (18) to (21) to obtain

The steering radius and yaw efficiency relationship of each drive wheel is shown in fig. 3.

As can be seen from fig. 3: in the case of a smaller steering radius, the yaw efficiency of the front two axles (steering axles) is higher, and the smaller the steering radius, the larger the difference thereof; when the swing torque is distributed, the yaw torque component of the wheels with high yaw torque efficiency is increased, so that the driving force utilization efficiency can be improved, and the dynamic response speed can be improved; when the steering radius of the vehicle is increased, the yaw rate is reduced, the required yaw moment is smaller, and the front two shafts are adopted for yaw moment synthesis to meet the steering requirement, so that the rear two shafts only need to provide the longitudinal force required by the vehicle to advance. The additional yaw moment is thus composed exclusively of the torque vectors of the steering wheels, i.e. the first two sets of vectors, the latter two sets of vectors only taking part in the composition of the longitudinal forces.

(2) Design torque vector controller

Fig. 4 shows a construction diagram of a torque vectoring controller according to the present invention. In FIG. 4, T ₁ ～T ₈ Torque for 8 wheels, T' _1-8 To synthesize the torque of 8 wheels required for longitudinal driving force, Δt _1-8 The front 4 wheel torque adjustment required to synthesize the additional yaw moment. As can be seen from fig. 4, the main torque vector control process is divided into the following two steps, step 1 is performed for total driving force synthesis, step 2 is performed for yaw moment synthesis, and motor torques of 8 driving wheels are obtained.

First, the total driving force for the vehicle to advance is synthesized according to the driver's demand and the vertical load proportion of the wheels. Since the vertical load of the wheel is a dynamic variable quantity during the running of the vehicle, the invention divides the vertical load into two parts for calculation, namely a static load and a dynamic variable quantity. The factors causing the dynamic change of the load are mainly acceleration/deceleration, steering, climbing, obstacle surmounting and the like of the vehicle, only the movement of the vehicle in a plane is considered, the influence factors such as climbing and obstacle surmounting of the vehicle are ignored, the roll and pitch movements are not considered, only the load change of the vehicle when the vehicle runs on a horizontal road surface is analyzed, and the load is considered to be influenced by longitudinal/lateral acceleration only. The vertical load of 8 wheels is expressed as

Wherein: f (F) _zij (i=1, 2,3,4 is the i-th axis, j=1, 2 is the left and right side) is the wheel vertical load; h represents the height of the mass center of the vehicle from the ground; a, a _x 、a _y For vehicle longitudinal and lateral acceleration. L (L) _a ，L _b As an intermediate variable, the number of the variables,

L _a ＝(L ₁ -L ₂ )+(L ₁ +L ₃ )+(L ₁ +L ₄ ) (24)

L _b ² ＝(L ₁ -L ₂ ) ² +(L ₁ +L ₃ ) ² +(L ₁ +L ₄ ) ² (25)

the total driving force demand of the vehicle is synthesized according to the vertical load proportion, and the calculation formula is that

Next, Δm obtained by the yaw moment controller is calculated _z The torque vectors of the front two shafts are synthesized according to the proportion, and the rear two shafts do not participate in yaw moment synthesis. Because the wheel angle of the 1 st axle is larger than the wheel angle of the 2 nd axle and the two have fixed proportion, the additional yaw moment is synthesized between the axles according to proportion, and the addition and subtraction of the two coaxial wheels are the same so as to maintain the total driving force unchanged, and the additional yaw moment has the following characteristics that

Wherein: Δfxij (i=1, 2 is the i-th axis, j=1, 2 is the left and right sides) is the wheel longitudinal force adjustment amount.

The driving force of each wheel satisfying the longitudinal force demand and the front four-wheel driving force adjustment amount satisfying the yaw moment demand can be obtained from the formulas (26) and (27). The final driving force can be obtained by adding the 8 wheel driving forces and the yaw moment adjustment amounts, respectively.

(3) Design slip rate controller

Since the driving force of the vehicle is limited by the maximum attachment coefficient of the ground, if the applied driving force is too large, the wheels will slip greatly, so that the lateral force approaches saturation, the lateral stability of the vehicle is rapidly reduced, and the slip rate when the wheels are driven must be controlled. Conventional mechanical vehicles typically control the slip rate of the wheels through a traction control system or differential lock. Each wheel of the armored vehicle driven by the hub motor is independently driven, and the armored vehicle is a relatively independent system and can control a single wheel. The main function of the anti-slip control is to reduce the given driving torque, and when the deviation e between the actual slip rate s and the expected slip rate sd is large, the given torque is required to be reduced rapidly, and the output value of the anti-slip control is large; when the deviation between s and sd is small, a certain steady state error needs to be eliminated. P control is adopted when the error is large, and PI control is adopted when the error is small. Fig. 5 shows a schematic diagram of a P-PI segment controller.

When partial wheels of the vehicle slip in the steering process, the anti-slip controller can reduce the torque output of the target motor, if the torque of other driving motors is not corrected, the yaw moment output of the whole vehicle is influenced inevitably, and the yaw moment output is different from an expected value, so that the expected stable steering of the vehicle cannot be realized.

From the viewpoint of maintaining the balance of the vehicle longitudinal driving force and yaw moment, there are two methods: firstly, the longitudinal driving force of the vehicle is kept unchanged, at this time, the lost driving moment (delta T) of the slip wheels can be evenly distributed to other non-slip wheels on the same side, and the method can lead to the yaw moment synthesized by the torque vectors among groups to be changed, so that the total yaw moment requirement can not be met. And secondly, the total yaw moment is kept unchanged, and the torque of the coaxial other driving wheel of the pulley wheel can be reduced by delta T at the same time, so that the yaw moment synthesized by the torque vectors among the groups is unchanged, but the total driving force of the vehicle is reduced. Considering that the reason why the vehicle slips is mainly that the road adhesion coefficient is low, the driving force of each wheel is close to the adhesion limit, the lateral force margin of the vehicle can be improved by reducing the torque, and the lateral stability and the steering stability of the vehicle are improved, so that a control method for maintaining the yaw moment unchanged is adopted.

3. Example verification

The invention adopts a real-time simulation experiment based on dSPACE software to verify the control system and the control method provided by the invention, and the structure of hardware on a real-time simulation platform is shown in figure 6. The platform realizes a closed-loop feedback system of a man-vehicle, which consists of a driver-controller (dsace) -a hub motor model (RT-Lab) -a vehicle model (Vortex).

The functions of each module of the hardware-in-loop real-time simulation platform are as follows:

1) The driver manipulates the system. The driver CAN operate the vehicle to run through an accelerator pedal, a brake pedal, a steering wheel, gears and the like, and the operating signals are transmitted to the dSPACE control terminal through the CAN bus.

2) A controller system. The system consists of a dSPACE real-time simulation system, and a control algorithm of a traveling vehicle sends a control signal to a driving motor through a bus according to a control instruction of a driver and a vehicle state.

3) A motor drive system. And running the real-time simulation model of the hub motor in the RT-Lab, receiving a control instruction sent by the controller, and sending the running state to the controller and the Vortex vehicle dynamics model.

4) A dynamic real-time simulation system. And carrying out real-time simulation and scene display of vehicle dynamics in the Vortex simulation system, obtaining the real-time running state of the vehicle and feeding back to other systems. Before the simulation experiment, the accuracy of the vehicle model is verified by comparison with a real vehicle experiment, so that the simulation requirement can be met.

The simulation object is an 8×8 distributed electrically driven wheeled armored vehicle, the main parameters of the vehicle and the motor are shown in table 1, and the motor type is a permanent magnet synchronous motor.

Table 1 vehicle and motor main parameters

1. Good road surface obstacle avoidance driving simulation

And (3) referring to a double-lane-change experimental method, simulating the driving process of the vehicle emergency obstacle avoidance, and checking part of the dynamic performance and the operation stability of the vehicle. The simulation conditions were: the road adhesion coefficient was 0.85, the initial vehicle speed was 60km/h, the time was 12s, the distance was 200m, and 8-wheel torque average distribution vehicles without yaw moment control were set as a control group. Fig. 7 shows the simulation results of this experiment.

According to the simulation result of fig. 7, the steering wheel and the pedal are first manipulated by the driver to make the vehicle travel along a predetermined trajectory. As can be seen from the simulation results in fig. 7: at 3s, the steering wheel angle starts to change, the vehicle without control drives the track to have a transverse deviation of 2.4m from an ideal track at a maximum point of transverse displacement, the maximum value of the yaw rate is 15.4 degrees/s, and the maximum value of the centroid side deflection angle is 2.3 degrees; after yaw moment control is applied, the torques of the wheels are redistributed, and torque differences are generated on the inner side and the outer side, so that yaw moment is generated, the moment of the outer side wheel is ensured to be larger than that of the inner side wheel when the vehicle turns, the transverse deviation of the driving track from the ideal track at the maximum point of transverse displacement is reduced to 0.5m, the yaw rate and the centroid side deviation angle are obviously reduced, and the change is more gentle. The result shows that the yaw moment and the torque vector control can play a control role, so that the vehicle can run according to a preset track, and the running stability of the vehicle is improved.

2. Split pavement acceleration driving simulation

In order to verify the control effect of the anti-skid controller when the wheel adhesion conditions at two sides are different, a split road surface driving simulation is carried out, and the road surface adhesion coefficients at two sides are respectively set to be 0.3 and 0.85. In the simulation process, a driver does not operate a steering wheel and only runs by stepping on an accelerator pedal, and the running states of the vehicle in a non-control state and a non-skid control state are recorded by taking the wheels at the left and right sides of a 1 st axle as observation objects, as shown in fig. 8.

As is clear from fig. 8 (a) and 8 (c), in the uncontrolled state, since the road surface adhesion systems on both sides are different, the wheel rotation speed on the low adhesion side is significantly higher than that on the high adhesion side, and the wheel slip occurs in the case where the given torque is the same; as is clear from fig. 8 (b) and 8 (d), by applying the slip prevention control, the low traction side wheel slip condition control is evident; as can be seen from fig. 8 (e), in the uncontrolled state, the torque value given by the accelerator pedal is distributed to the left and right motors, the actual output value of the high adhesion side motor substantially coincides with the given value, while the motor speed is excessively high due to wheel slip on the low adhesion side, and the actual output torque of the motor is significantly lower than the given value of the accelerator pedal; as is clear from a comparison of fig. 8 (e) and 8 (f), under the anti-skid control, the low traction side wheel torque is adjusted, the slip state of the wheels is improved, and at the same time, the high traction side wheel torque is adjusted so that the total yaw moment is zero, and the lateral stability of the vehicle is maintained.

In summary, the invention provides a direct yaw moment and torque vector control method for an 8×8 distributed electrically driven wheeled armored vehicle. In the implementation process of the invention, a layered controller is designed, an upper layer controller adopts sliding mode control to respectively calculate the yaw rate and the yaw moment of the centroid side deflection angle, and a weighting function is designed to coordinate the yaw rate and the yaw moment to output the total yaw moment. The lower controller divides 8 wheels into 4 groups of vectors according to the shaft, obtains each wheel torque according to the yaw moment and the longitudinal force demand and a torque vector synthesis method, and designs an anti-skid controller to control the slip ratio of the wheels. The invention also adopts hardware to verify the proposed control method in a real-time simulation platform. Experimental results show that under the action of the proposed control strategy, the vehicle has better response characteristics compared with a vehicle without control, the actual yaw rate and the running track well track expected values, and the running stability of the vehicle is improved.

Although the invention has been described with reference to the embodiments shown in the drawings, equivalent or alternative means may be used without departing from the scope of the claims. The components described and illustrated herein are merely examples of systems/devices and methods that may be used to implement embodiments of the present disclosure and may be replaced with other devices and components without departing from the scope of the claims.

Claims

1. A matrix vector travel control method for a motor-driven wheeled vehicle, comprising:

constructing a plane motion model of the motor-driven wheeled vehicle, wherein the motion model outputs expected yaw rate and centroid slip angle;

designing a whole vehicle controller based on the plane motion model; it is characterized in that the method comprises the steps of,

the whole vehicle controller comprises an upper controller and a lower controller;

the upper controller is a yaw moment controller, which includes:

the centroid slip angle control module receives the centroid slip angle as input and outputs moment required by centroid slip angle control;

and a yaw rate control module that receives the centroid slip angle as an input and outputs a moment required for yaw rate control;

the moment required by the centroid side deflection angle control and the moment required by the yaw rate control are controlled by a coordination control module to obtain a final output control quantity;

the final output control amount is input to the lower controller to perform torque vector control and slip ratio control, thereby outputting a torque required for each wheel of the motor-driven wheeled vehicle, thereby controlling the motor-driven wheeled vehicle.

2. The matrix vector travel control method according to claim 1, wherein the lower controller includes a torque vector control module and a slip ratio control module, the torque vector control module takes an output of the yaw moment controller as an input, outputs a motor torque of a driving wheel, and the motor torque of the driving wheel is corrected by the slip ratio control module.

3. The matrix vector travel control method according to claim 1, wherein the yaw-rate control module includes a yaw-rate slide controller whose slide surface is:

wherein P is an intermediate variable,

order the

4. The matrix vector travel control method of claim 1 wherein the centroid slip angle control module comprises a centroid slip angle slide controller having a slide surface of:

5. the matrix vector travel control method according to claim 1, wherein the coordination control module includes a weighting function G via which a yaw rate and a centroid slip angle are adjusted, and the final output control amount Δm of the yaw moment controller after the adjustment _z Is of the size of

ΔM _z ＝G·ΔM _γ +(1-G)ΔM _β

Wherein the weighting function is:

6. The matrix vector travel control method according to claim 5, characterized by further comprising: final output control quantity Δm for the yaw moment controller _z Synthesizing by using a torque vector method, wherein the synthesizing step comprises total driving force synthesis and yaw moment synthesis; the wheel torque of the motor-driven wheeled vehicle is divided into four groups by the shaft, and the longitudinal force F of the vehicle _xd And yaw moment M _z The size of (2) is:

7. The matrix vector travel control method according to claim 1, characterized in that the lower-layer controller includes a torque vector control layer at which torque vector control including total driving force synthesis and yaw moment synthesis and slip ratio control are performed.

8. The matrix vector travel control method according to claim 7, characterized in that the total driving force synthesis synthesizes the total driving force of the vehicle forward movement according to the driver's demand and the vertical load proportion of the wheels.

9. The matrix vector travel control method according to claim 8, characterized in that the yaw moment synthesis includes: Δm obtained by yaw moment controller _z The torque vectors of the front two shafts are synthesized according to the proportion, the yaw moment is not participated in by the rear two shafts, wherein the additional yaw moment is synthesized according to the proportion between the shafts, the addition and subtraction of the two wheels on the same axis are the same so as to maintain the total driving force unchanged, wherein

10. The matrix vector travel controller according to claim 7The method is characterized in that the slip ratio control comprises single-wheel drive slip control and coaxial torque adjustment; the purpose of the slip control is to reduce drive torque setting; at the actual slip rate s and the desired slip rate s _d When the deviation e is large, the given torque is rapidly reduced; at s and s _d And when the deviation is smaller, eliminating a certain steady-state error.

11. The matrix vector travel control method of claim 10 wherein the antiskid control employs a PPI controller; p control is adopted when the error is large, and PI control is adopted when the error is small.