CN101298256B

CN101298256B - Electric power steering device and control method thereof

Info

Publication number: CN101298256B
Application number: CN2008100536329A
Authority: CN
Inventors: 孙鹤旭; 李练兵; 莫红影
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2008-06-25
Filing date: 2008-06-25
Publication date: 2011-01-19
Anticipated expiration: 2028-06-25
Also published as: CN101298256A

Abstract

The invention relates to an electric power steering device (EPS device) and a control method for the electric power steering device, comprising a torque sensor, a vehicle speed sensor, a current sensor, an electronic control unit (ECU), a power motor and a reducing mechanism; the electric power steering device also comprises a wheel static controller which consists of a transverse swing angular speed instruction generator, a state observer, a torque distribution controller and a tyre sliding controller. The EPS device and the control arithmetic of the EPS device compensate the problems of insufficient steering or over-steering due to the road surface or vehicle conditions, ensure the precise steering of the electric power system, ensure the normal steering of the automobile when the steering power system is failed and the steering power function can not be maintained by the EPS device, and have an guarantee failure safety control function. The control method of the invention adjusts the torque of all wheels under the situation of failure of the existing EPS system or insufficient steering and over-steering, forms the vehicle steering moment, ensures the completion of the steering action, completes the EPS failure safety control, and avoids the happening of the traffic accidents. The EPS device and the control method for the EPS device have the advantages of quick operation, reliable operation, low cost, etc.

Description

Electric power steering device and control method thereof

技术领域technical field

本发明涉及一种电动助力转向装置及其控制方法，具体为一种四轮制动分配控制的电动助力转向装置的故障安全控制策略。The invention relates to an electric power steering device and a control method thereof, in particular to a fail-safe control strategy of an electric power steering device with four-wheel brake distribution control.

背景技术Background technique

电动助力转向系统(EPS，Electric Power Steering)作为汽车主动安全性的关键组成，它直接影响着车辆2运行时的安全和操纵稳定性。随着现代汽车技术的迅猛发展，汽车转向机构的安全性也逐渐成为研究的重点。近年来，随着人们对安全、环保和节能的呼声越来越高，汽车电动助力转向系统作为一种“按需型”的转向机构受到业界的普遍青睐，代表了未来汽车转向技术的发展方向。当前技术中存在的缺陷有：(1)EPS本身难以补偿由于路面和车况原因造成的转向不足(under steering)和转向过度(over steering)问题，(2)在EPS失效的情况下，自身无法维持转向助力控制功能。当车辆2疾速行驶时，车轮与路面之问的附着力降低，即使是最好的驾驶员也很难将高速行驶的汽车保持在预定的路线上，汽车容易发生侧滑和跑偏，失去方向稳定性，甚至在急转弯的时候发生翻车事故，这时就需要EPS系统以避免交通事故的发生。但当EPS系统出现故障不能正常运行时，在转弯的时候容易发生翻车事故。Electric Power Steering (EPS, Electric Power Steering) is a key component of automobile active safety, which directly affects the safety and handling stability of the vehicle 2 during operation. With the rapid development of modern automobile technology, the safety of automobile steering mechanism has gradually become the focus of research. In recent years, as people's calls for safety, environmental protection and energy saving have become higher and higher, automotive electric power steering systems, as an "on-demand" steering mechanism, have been generally favored by the industry, representing the future development direction of automotive steering technology . The defects in the current technology are: (1) EPS itself is difficult to compensate for understeering and oversteering (oversteering) problems caused by road surface and vehicle conditions; (2) in the case of EPS failure, it cannot maintain Power steering control function. When the vehicle 2 is running at high speed, the adhesion between the wheels and the road surface is reduced, and it is difficult for even the best driver to keep the high-speed car on the predetermined route. Directional stability, even when a rollover accident occurs during a sharp turn, the EPS system is needed to avoid traffic accidents. However, when the EPS system fails and cannot operate normally, rollover accidents are prone to occur when turning.

EPS系统故障的安全控制问题可以表述如下：在汽车行驶过程中，因外界干扰，比如行人、车辆2或环境等突然变化(结冰、湿滑，以及碎石等)情况下，驾驶员采取一些紧急避让措施，使汽车进入不稳定行驶状态，即出现偏离预定行驶路线或翻转趋势等危险状态，而此时EPS系统的任意一个或几个环节发生故障，驾驶员做出反应，方向盘9有角度时，可以利用方向盘转角传感器检测方向盘9产生的角度，采用X-By-Wire系统用电来控制会大大地减小延迟，为危险情况下的紧急处理赢得了宝贵的时间，方向盘9无角度时可以利用力矩传感器检测扭动力矩来达到对车身的控制。从而能够自动并及时地帮助驾驶员改善汽车稳定性。The safety control problem of EPS system failure can be expressed as follows: During the driving process of the car, due to external disturbances, such as pedestrians, vehicles 2 or sudden changes in the environment (icing, wet slippery, and gravel, etc.), the driver takes some measures. Emergency avoidance measures make the car enter an unstable driving state, that is, a dangerous state such as deviating from the predetermined driving route or turning over, and at this time, any one or several links of the EPS system fail, the driver responds, and the steering wheel 9 has an angle When using the steering wheel angle sensor to detect the angle generated by the steering wheel 9, using the X-By-Wire system to control the electricity will greatly reduce the delay and win valuable time for emergency treatment in dangerous situations. When the steering wheel 9 has no angle The torque sensor can be used to detect the torque to achieve the control of the vehicle body. This can automatically and timely help the driver to improve the stability of the car.

发明内容Contents of the invention

本发明的目的在于提供一种电动助力转向装置及其控制方法，可以克服现有技术的缺陷。本发明是对四轮制动力矩或驱动力矩信号分配，辅助EPS转向或镇定车体动态，确保转向动作的完成，实现EPS故障安全控制，保证车辆的安全控制。The object of the present invention is to provide an electric power steering device and a control method thereof, which can overcome the defects of the prior art. The invention distributes four-wheel braking torque or driving torque signals, assists EPS steering or stabilizes vehicle body dynamics, ensures completion of steering action, realizes EPS fail-safe control, and ensures vehicle safety control.

本发明提供的电动助力转向装置包括：扭矩传感器、车速传感器、电流传感器、控制单元ECU(Electronic Control Unit)、助力电动机和减速机构；方向盘由输入轴与扭矩传感器连接在一起，扭矩传感器还与助力电动机连接在一起，扭矩传感器和助力电动机都与控制单元ECU连接。还包括车轮镇定控制器，组成为：The electric power steering device provided by the present invention includes: a torque sensor, a vehicle speed sensor, a current sensor, a control unit ECU (Electronic Control Unit), a booster motor and a reduction mechanism; the steering wheel is connected with the torque sensor by an input shaft, and the torque sensor is also connected with the power boost The electric motors are connected together, and both the torque sensor and the assist motor are connected with the control unit ECU. Also includes wheel stabilization controller, consisting of:

车轮镇定控制器和四轮驱动或制动力矩控制信号输出装置，车轮镇定控制器的组成为：Wheel stabilization controller and four-wheel drive or braking torque control signal output device, the composition of the wheel stabilization controller is:

横摆角速度指令发生器，用于得到横摆角速度指令值；The yaw rate command generator is used to obtain the yaw rate command value;

状态观测器，用于获得实际的横摆角速度值和侧滑角度值；State observer, used to obtain the actual yaw rate value and sideslip angle value;

转矩分配控制器，将不同大小的驱动转矩或制动转矩分别加到各个车轮上，形成转向力矩，使转向响应速度加快；The torque distribution controller adds different driving torques or braking torques to each wheel to form steering torque and speed up the steering response;

轮胎打滑控制器，通过调节车辆轮胎与路面间的作用力，提高汽车的主动安全性能。The tire slip controller improves the active safety performance of the vehicle by adjusting the force between the vehicle tire and the road surface.

所述的横摆角速度指令发生器是通过检测转向轮的转向角度δ_f与侧滑角β之差乘以速度v再除以重心与转向轮之间的距离l_f得到横摆角速度指令值γ^*。The yaw rate command generator obtains the yaw rate command value γ by multiplying the difference between the steering angle δ _f of the steering wheel and the sideslip angle β by the speed v and then dividing by the distance l _f between the center of gravity and the steering wheel ^* .

所述的状态观测器包括两个输入，即u和y，输出为观测器含n个积分器并对全部状态变量作出估计，G为观测器输出反馈阵，它把

负反馈至

处，使为配置观测器极点，提高其动态性能，尽快使

逼近于零而引入的，它是一种输出反馈。The state observer includes two inputs, i.e. u and y, and the output is The observer contains n integrators and estimates all the state variables, G is the observer output feedback array, it puts

negative feedback to

In order to configure the observer poles and improve its dynamic performance, use

Introduced by approaching zero, it is a kind of output feedback.

所述的转矩分配控制器是根据车体稳定所需要的旋转力矩大小，前后车轮组平均分配驱动力矩，左右车轮组互补分配转向力矩；或者采用只在前轮或后轮上对转矩进行平均分配。The torque distribution controller is based on the size of the rotation torque required for the stability of the car body, the front and rear wheel groups distribute the drive torque equally, and the left and right wheel groups complement each other to distribute the steering torque; equally distributed.

所述的轮胎打滑控制器是基于车轮速度计算加速度及驱动力信号，观测车体等效转动惯量，构建外部扰动信号观测器，从而形成轮胎打滑控制器。The tire slip controller calculates the acceleration and driving force signals based on the wheel speed, observes the equivalent moment of inertia of the vehicle body, and constructs an external disturbance signal observer to form a tire slip controller.

本发明提供的电动助力转向控制方法包括的步骤：The electric power steering control method provided by the present invention includes the steps:

1)通过检测方向盘的转角或转矩得到转向轮的转向角度；1) Obtain the steering angle of the steering wheel by detecting the rotation angle or torque of the steering wheel;

2)通过车身横摆角速度指令发生器得到预期的横摆角速度指令值；2) Obtain the expected yaw rate command value through the vehicle body yaw rate command generator;

3)通过状态观测器获得实际的横摆角速度和侧滑角度值；3) Obtain the actual yaw rate and sideslip angle value through the state observer;

4)采用前馈和PI调节器调节辅助转向转矩，通过转矩分配控制器将不同大小的驱动转矩或制动转矩分别加到各个车轮上，形成转向力矩，使转向响应速度加快、动作准确。4) Use feedforward and PI regulators to adjust the auxiliary steering torque, and add different driving torques or braking torques to each wheel through the torque distribution controller to form steering torque, so that the steering response speed is accelerated, The action is accurate.

5)轮胎打滑控制器通过调节车辆轮胎与路面间的作用力，提高汽车的主动安全性能。5) The tire slip controller improves the active safety performance of the vehicle by adjusting the force between the vehicle tire and the road surface.

当EPS失效时，通过检测方向盘的转角或转矩确定驾驶员希望的转向角δ_f，调节各个车轮的驱动转矩或制动转矩，形成车身转向力矩，强制车身按照驾驶员的控制要求转向，实现EPS的故障安全功能。When the EPS fails, the steering angle _δf desired by the driver is determined by detecting the steering wheel angle or torque, and the driving torque or braking torque of each wheel is adjusted to form the steering torque of the vehicle body, forcing the vehicle body to turn according to the driver's control requirements , to realize the fail-safe function of EPS.

本发明提供一种电动助力转向装置及其控制方法可以克服现有技术的缺陷。本发明是对四轮制动与驱动力矩信号分配，辅助EPS转向或镇定车体动态，确保转向动作的完成，实现EPS故障安全控制，保证车辆的安全控制。特别是：The invention provides an electric power steering device and a control method thereof, which can overcome the defects of the prior art. The invention distributes four-wheel braking and driving moment signals, assists EPS steering or stabilizes vehicle body dynamics, ensures completion of steering action, realizes EPS fail-safe control, and ensures vehicle safety control. in particular:

(1)适于在出现EPS本身难以补偿的由于路面和车况等原因造成的转向不足和转向过度问题时，确保转向动作的安全完成，避免交通事故的发生。(1) It is suitable for ensuring the safe completion of the steering action and avoiding traffic accidents when there are understeer and oversteer problems caused by road surface and vehicle conditions that EPS itself is difficult to compensate.

(2)在EPS失效的情况下，仍能准确保证汽车行驶的稳定性，避免了交通事故的发生。该设计具有操作快速、运行可靠、成本低等优点。(2) In the case of EPS failure, the stability of the vehicle can still be accurately guaranteed, and the occurrence of traffic accidents can be avoided. The design has the advantages of fast operation, reliable operation and low cost.

附图说明Description of drawings

图1为司机-车辆模型。Figure 1 shows the driver-vehicle model.

图2为车辆坐标系与汽车的主要运动形式。Figure 2 shows the vehicle coordinate system and the main movement forms of the car.

图3为状态观测器的结构框图。Figure 3 is a block diagram of the state observer.

图4为将车身坐标和路面坐标投影到水平面。Figure 4 shows the projection of the vehicle body coordinates and road surface coordinates to the horizontal plane.

图5为打滑控制器的结构框图。Figure 5 is a structural block diagram of the slip controller.

图6为车轮镇定控制器模型。Figure 6 is the wheel stabilization controller model.

图7为电动助力转向装置的结构示意图。Fig. 7 is a schematic structural diagram of an electric power steering device.

图8是本发明的控制流程图。Fig. 8 is a control flow diagram of the present invention.

图9是本发明的控制流程图。Fig. 9 is a control flow diagram of the present invention.

图10是车辆重心轨迹仿真曲线。Fig. 10 is the simulation curve of the track of the center of gravity of the vehicle.

图11是不带有本发明装置的EPS故障失效后的横摆角速度和转向曲线。Fig. 11 is the yaw rate and steering curves after the failure of the EPS without the device of the present invention.

图12是带有本发明装置的EPS故障失效后的横摆角速度和转向轨迹曲线。Fig. 12 is the yaw rate and steering trajectory curves after the failure of the EPS with the device of the present invention.

具体实施方式Detailed ways

下面结合附图和实施例对本发明进一步说明。The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

如图所示，1是司机，2是车辆，3是电动转向器，4是所需侧向速度，5是助力扭矩，6是汽车横摆角速度，7是转向角，8是司机扭矩，9是操纵方向盘，10是扭矩传感器，11是助力电动机，12是四轮驱制动信号，13是传感器信号，15是加速度，16是控制单元ECU，17扭矩传感器信号，18是助力电流。As shown in the figure, 1 is the driver, 2 is the vehicle, 3 is the electric steering gear, 4 is the required lateral speed, 5 is the assist torque, 6 is the vehicle yaw rate, 7 is the steering angle, 8 is the driver torque, 9 10 is the torque sensor, 11 is the power-assisted motor, 12 is the four-wheel drive braking signal, 13 is the sensor signal, 15 is the acceleration, 16 is the control unit ECU, 17 is the torque sensor signal, and 18 is the power-assisted current.

EPS由扭矩传感器10、车速传感器、电流传感器、控制单元ECU16、助力电动机11和减速机构等组成。其中，扭矩传感器10和转角传感器是EPS中最为核心的传感器。早期的EPS，特别是低速型(只在某一车速以下提供助力效果)EPS，还带有电磁离合器。当车速超过某一设定值(如30km/h)时，由于高速时转向阻力力矩减小，驾驶员操纵方向盘9即可转向，ECU 16控制电磁离合器分开，此时相当于手动转向。带有离合器的EPS在出现故障时，由ECU 16控制离合器分开，断开电动机的助力效果，系统进入手动转向模式。The EPS is composed of a torque sensor 10 , a vehicle speed sensor, a current sensor, a control unit ECU 16 , an assist motor 11 , and a speed reduction mechanism. Among them, the torque sensor 10 and the rotation angle sensor are the most core sensors in the EPS. The early EPS, especially the low-speed type (which only provides a boost effect below a certain speed) EPS, also has an electromagnetic clutch. When the vehicle speed exceeds a certain set value (such as 30km/h), due to the reduced steering resistance torque at high speed, the driver can steer the steering wheel 9, and the ECU 16 controls the electromagnetic clutch to separate, which is equivalent to manual steering. When the EPS with clutch breaks down, the ECU 16 controls the clutch to separate, disconnects the power assist effect of the motor, and the system enters the manual steering mode.

EPS工作过程原理为：扭矩传感器10与转向轴(小齿轮轴)连接在一起，驾驶员转动方向盘9时，扭矩传感器10开始工作，把输入轴和输出轴在扭杆作用下产生的相对转动位移变成电信号传给ECU16，ECU16根据车速传感器信号13、扭矩传感器信号17和x、y加速度15决定电动机的旋转方向和助力电流18大小，并输出四轮驱制动信号12，通过对四轮制动力矩或驱动力矩的分配，辅助EPS转向或镇定车体动态，从而实时控制助力转向。它可以很容易实现电动机在不同车速时提供不同的助力效果，保证汽车低速行驶时轻便灵活，高速行驶时稳定可靠。因此EPS转向特性的设置具有较高的自由度。The working principle of EPS is: the torque sensor 10 is connected with the steering shaft (pinion shaft). When the driver turns the steering wheel 9, the torque sensor 10 starts to work, and the relative rotational displacement generated by the input shaft and output shaft under the action of the torsion bar It becomes an electrical signal and transmits it to ECU16. ECU16 determines the direction of rotation of the motor and the size of the assist current 18 according to the vehicle speed sensor signal 13, torque sensor signal 17 and x, y acceleration 15, and outputs four-wheel drive braking signal 12. The distribution of braking torque or driving torque assists EPS steering or stabilizes vehicle body dynamics, thereby controlling power steering in real time. It can easily realize that the electric motor provides different boosting effects at different speeds, ensuring that the car is light and flexible when driving at low speeds, and stable and reliable when driving at high speeds. Therefore, the setting of EPS steering characteristics has a high degree of freedom.

图1描述了车身在空间运动的六个自由度及坐标系。以车辆坐标系为基准，可将汽车的运动分解为：(1)沿x轴的纵向运动；(2)沿y轴的侧向运动；(3)沿z轴的垂直运动；(4)绕x轴的侧倾运动；(5)绕y轴的俯仰运动；(6)绕z轴的横摆运动。一般认为汽车的横摆角速度γ6和质心侧偏角β是描述汽车运动状态的重要参数，这两个参数能够在很大程度上表征汽车的稳定性。因此在对汽车进行操纵稳定性的分析中主要考虑与这两个参数密切相关的纵向运动、横摆运动和侧向运动。Figure 1 describes the six degrees of freedom and the coordinate system of the body moving in space. Based on the vehicle coordinate system, the motion of the car can be decomposed into: (1) longitudinal motion along the x-axis; (2) lateral motion along the y-axis; (3) vertical motion along the z-axis; Rolling motion around the x-axis; (5) pitching motion around the y-axis; (6) yaw motion around the z-axis. It is generally believed that the yaw rate γ6 and the side slip angle β of the car are important parameters to describe the motion state of the car, and these two parameters can characterize the stability of the car to a large extent. Therefore, in the analysis of vehicle handling stability, the longitudinal motion, yaw motion and lateral motion closely related to these two parameters are mainly considered.

图2为将图1的车辆坐标系和路面坐标系投影到水平面的三自由度汽车模型，忽略前后轮距的微小差别，P为车辆的重心，l_f为P到前轴的距离，l_r为P到后轴的距离，α_f为前轮侧偏角，α_r为后轮侧偏角，δ_f为转向轮的转向角度，v为车速。F_{x_fl}，F_{x_fr}，F_{x_rr}，F_{x_} _rl分别为左前、右前、左后、右后轮胎纵向力F_{y_fl}，F_{y_fr}，F_{y_rl}，F_{y_rr}分别为左前、右前、左后、右后轮胎横向力，I为汽车的转动惯量。γ为汽车横摆角速度6。β为汽车车体侧滑角。N为左右侧受力之差造成的车身转向扭矩。Figure 2 is a three-degree-of-freedom vehicle model that projects the vehicle coordinate system and road surface coordinate system in Figure 1 onto the horizontal plane, ignoring the small difference between the front and rear wheelbases, P is the center of gravity of the vehicle, l _f is the distance from P to the front axle, l _r is the distance from P to the rear axle, α _f is the side slip angle of the front wheel, α _r is the side slip angle of the rear wheel, δ _f is the steering angle of the steering wheel, and v is the vehicle speed. F _{x_fl} , F _{x_fr} , F _{x_rr} , F _{x_rl} are the tire longitudinal force F _{y_fl} , F _{y_fr} , F _{y_rl} , _{F y_rr} _are the left front, right front, left rear, right rear tire transverse force respectively Force, I is the moment of inertia of the car. γ is the vehicle yaw rate6. β is the sideslip angle of the vehicle body. N is the body steering torque caused by the difference between the left and right sides.

根据牛顿力学定律列出如下汽车运动方程：According to Newton's laws of mechanics, the equations of motion of the car are listed as follows:

纵向运动：ma_x＝F_{x_fl}+F_{x_fr}+F_{x_rl}+F_{x_rr} Longitudinal movement: max _x = F _{x_fl} + F _{x_fr} + F _{x_rl} + F _{x_rr}

横向运动：ma_y＝F_{y_fl}+F_{y_fr}+F_{y_rl}+F_{y_rr} Lateral movement: ma _y =F _{y_fl} +F _{y_fr} +F _{y_rl} +F _{y_rr}

摆运动： $I \overset{\cdot}{γ} = l_{f} (F_{y_fl} + F_{y_fr}) - l_{r} (F_{y_rl} + F_{y_rr}) + N$ pendulum movement: $I \overset{\cdot}{γ} = l_{f} (f_{the y_fl} + f_{the y_fr}) - l_{r} (f_{the y_rl} + f_{the y_rr}) + N$

$N N = = \frac{d d}{22} ((- - {F f}_{x x__fl fl} + + {F f}_{x x__fr fr} - - {F f}_{x x__rl rl} + + {F f}_{x x__rr rr}))$

轮胎所受的横向力可由下式表示：The lateral force on the tire can be expressed by the following formula:

F_{y_fl}＝α_fC_fl F_{y_fr}＝α_fC_fr F _{y_fl} = α _f C _fl F _{y_fr} = α _f C _fr

F_{y_rl}＝α_rC_rl F_{y_rr}＝α_rC_rr F _{y_rl} = α _r C _rl F _{y_rr} = α _r C _rr

C_fl～C_rr分别是每个轮的侧偏刚度。C _fl to C _rr are the cornering stiffnesses of each wheel, respectively.

将车身速度在车轮中心平行于车身坐标系的方向进行分解，即可求得车轮中心在车身坐标上的速度分量Decompose the vehicle body speed in the direction of the wheel center parallel to the body coordinate system, and then the velocity component of the wheel center on the body coordinate system can be obtained

${v v}_{x x__fl fl} = = v v cos cos β β - - \frac{γd γ d}{22},, {v v}_{y the y__fl fl} = = v v sin sin β β + + γ γ {l l}_{f f}$

${v v}_{x x__fr fr} = = v v cos cos β β + + \frac{γd γ d}{22},, {v v}_{y the y__fr fr} = = v v sin sin β β + + γ γ {l l}_{f f}$

${v v}_{x x__rl rl} = = v v cos cos β β - - \frac{γd γ d}{22},, {v v}_{y the y__rl rl} = = v v sin sin β β - - γ γ {l l}_{r r}$

${v v}_{x x__rr rr} = = v v cos cos β β + + \frac{γd γ d}{22},, {v v}_{y the y__rr rr} = = v v sin sin β β - - γ γ {l l}_{r r}$

因此各轮胎的侧偏角(车本身斜向行进的速度与轮胎有一定夹角)的表达式为：Therefore, the expression of the side slip angle of each tire (the speed of the car itself traveling obliquely and the tire has a certain angle) is:

${α α}_{f f 11} = = arctan arctan ((\frac{{v v}_{y the y__fl fl}}{{v v}_{x x__fl fl}})) - - {δ δ}_{f f 11} = = arctan arctan ((\frac{v v sin sin β β + + γ γ {l l}_{f f}}{v v cos cos β β - - \frac{γd γd}{22}})) - - {δ δ}_{f f 11}$

${α α}_{r r 11} = = arctan arctan ((\frac{{v v}_{y the y__rl rl}}{{v v}_{x x__rl rl}})) = = arctan arctan ((\frac{v v sin sin β β - - γ γ {l l}_{r r}}{v v cos cos β β - - \frac{γd γd}{22}}))$

${α α}_{f f 22} = = arctan arctan ((\frac{{v v}_{y the y__fr fr}}{{v v}_{x x__fr fr}})) - - {δ δ}_{f f 22} = = arctan arctan ((\frac{v v sin sin β β + + γ γ {l l}_{f f}}{v v cos cos β β + + \frac{γd γd}{22}})) - - {δ δ}_{f f 22}$

${α α}_{r r 22} = = arctan arctan ((\frac{{v v}_{y the y__rr rr}}{{v v}_{x x__rr rr}})) = = arctan arctan ((\frac{v v sin sin β β - - γ γ {l l}_{r r}}{v v cos cos β β + + \frac{γd γd}{22}}))$

把静止坐标系X-O-Y下的加速度分别投影到车身坐标系x-y的x轴、y轴上：Project the acceleration in the static coordinate system X-O-Y onto the x-axis and y-axis of the body coordinate system x-y respectively:

${a a}_{x x} = = - - v v ((\overset{\cdot &Center Dot;}{β β} + + γ γ)) sin sin β β + + \overset{\cdot &Center Dot;}{v v} cos cos β β$

${a a}_{y the y} = = v v ((\overset{\cdot \cdot}{β β} + + γ γ)) cos cos β β + + \overset{\cdot &Center Dot;}{v v} sin sin β β$

这样得到汽车的加速度为：This gives the acceleration of the car as:

$\overset{\cdot &Center Dot;}{v v} = = a a = = {a a}_{x x} cos cos β β {+ + a a}_{y the y} sin sin β β + + v v ((\overset{\cdot &Center Dot;}{β β} + + γ γ)) sin sin β β cos cos β β - - v v ((\overset{\cdot \cdot}{β β} + + γ γ)) cos cos β β$

电动汽车的重心侧滑角β的表达式为：The expression of the sideslip angle β of the center of gravity of the electric vehicle is:

$β β = = arctan arctan ((\frac{{v v}_{y the y}}{{v v}_{x x}}))$

将β、γ作为状态量，系统的状态方程为：Taking β and γ as the state quantities, the state equation of the system is:

$\overset{\cdot &Center Dot;}{x x} = = Ax Ax + + Bu Bu$

其中，in,

$A A = = [\begin{matrix} \frac{(({C C}_{fl fl} + + {C C}_{fr fr} + + {C C}_{rl rl} + + {C C}_{rr rr}))}{mv mv} & \frac{{l l}_{f f} (({C C}_{fl fl} + + {C C}_{fr fr})) - - {l l}_{r r} (({C C}_{rl rl} + + {C C}_{rr rr}))}{m m {v v}^{22}} - - 11 \\ \frac{{l l}_{f f} (({C C}_{fl fl} + + {C C}_{fr fr})) - - {l l}_{r r} (({C C}_{rl rl} + + {C C}_{rr rr}))}{I I} & \frac{{l l}_{f f}^{22} (({C C}_{fl fl} + + {C C}_{fr fr})) + + {l l}_{r r}^{22} (({C C}_{rl rl} + + {C C}_{rr rr}))}{Iv IV} \end{matrix}]$

$B B = = [\begin{matrix} - - \frac{{C C}_{fl fl} + + {C C}_{fr fr}}{mv mv} & 00 \\ - - \frac{{l l}_{f f} (({C C}_{fl fl} + + {C C}_{fr fr}))}{I I} & \frac{11}{I I} \end{matrix}],,$ $x x = = [\begin{matrix} β β \\ γ γ \end{matrix}],,$ $u u = = [\begin{matrix} {δ δ}_{f f} \\ N N \end{matrix}]$

图3为构造的β角状态观测器的结构示意图。为充分反映车辆在线性区和非线性区的运行状态，将全部的状态变量(车身横摆角速度γ和车体侧滑角β)都用于状态观测器的状态估计中，并将车辆横摆角速度γ和车体侧向加速度a_y作为状态观测器的输出反馈变量。为此，在状态观测器设计中，首先重新构造a_y：Fig. 3 is a structural schematic diagram of the constructed β angle state observer. In order to fully reflect the running state of the vehicle in the linear region and the nonlinear region, all the state variables (body yaw rate γ and body sideslip angle β) are used in the state estimation of the state observer, and the vehicle yaw rate The angular velocity γ and the lateral acceleration a _y of the vehicle body are used as the output feedback variables of the state observer. To do this, in the state observer design, a _y is first reconstructed:

a_y＝v(a₁₁β+a₁₂γ+b₁₁δ+γ)a _y =v(a ₁₁ β+a ₁₂ γ+b ₁₁ δ+γ)

该状态观测器的状态方程及输出方程为：The state equation and output equation of the state observer are:

$\overset{\cdot \cdot}{\overset{^^}{x x}} = = A A \overset{^^}{x x} + + Bu Bu - - G G ((\overset{^^}{y the y} - - y the y))$

$\overset{^^}{y the y} = = C C \overset{^^}{x x} + + Du Du$

式中：In the formula:

C＝[va₁₁v(a₁₂+1)]，D＝[vb₁₁ 0]，y＝[a_y]C=[va ₁₁ v(a ₁₂ +1)], D=[vb ₁₁ 0], y=[a _y ]

G是状态观测器的反馈增益矩阵，

是x的估计值。G is the feedback gain matrix of the state observer,

is the estimated value of x.

系统的可观性由下式决定：The observability of the system is determined by the following formula:

$rank rank [\begin{matrix} C C \\ CA CA \end{matrix}] = = rank rank [\begin{matrix} {va va}_{1111} & v v (({a a}_{1212} + + 11)) \\ {va va}_{1111}^{22} + + v v (({a a}_{1212} + + 11)) {a a}_{21 twenty one} & {va va}_{1111} {a a}_{1212} + + v v (({a a}_{1212} + + 11)) {a a}_{22 twenty two} \end{matrix}] &NotEqual; &NotEqual; 00$

化简得：Simplified:

${a a}_{1111} {a a}_{22 twenty two} {a a}_{1212} + + {a a}_{1111} {a a}_{22 twenty two} - - {a a}_{1111}^{22} - - {a a}_{1212}^{22} {a a}_{21 twenty one} - - {22 a a}_{1212} {a a}_{21 twenty one} - - {a a}_{21 twenty one} &NotEqual; &NotEqual; 00$

状态观测器鲁棒性和稳定性的关键首先在于合理构造增益矩阵G的值，即G值的设计要考虑减小模型误差的影响，同时，矩阵A-GC的特征值都应该在稳定的区域内。The key to the robustness and stability of the state observer lies in the reasonable construction of the value of the gain matrix G, that is, the design of the G value should consider reducing the influence of model errors, and at the same time, the eigenvalues of the matrix A-GC should be in a stable area Inside.

状态观测器的系数矩阵为：A+GCThe coefficient matrix of the state observer is: A+GC

$A A + + GC GC = = [\begin{matrix} {a a}_{1111} & {a a}_{1212} \\ {a a}_{21 twenty one} & {a a}_{22 twenty two} \end{matrix}] - - [\begin{matrix} {g g}_{11} \\ {g g}_{22} \end{matrix}] [\begin{matrix} {va va}_{1111} & v v (({a a}_{1212} + + 11)) \end{matrix}]$

$= = [\begin{matrix} {a a}_{1111} - - {g g}_{11} {va va}_{1111} & {a a}_{1212} - - {g g}_{11} v v (({a a}_{1212} + + 11)) \\ {a a}_{21 twenty one} - - {g g}_{22} v v {a a}_{1111} & {a a}_{22 twenty two} - - {g g}_{22} v v (({a a}_{1212} + + 11)) \end{matrix}]$

状态观测器特征方程为：The characteristic equation of the state observer is:

$f f ((s the s)) = = | | SI Si - - ((A A - - GC GC)) | | = = |\begin{matrix} s the s - - {a a}_{1111} + + {g g}_{11} v v {a a}_{1111} & - - {a a}_{1212} + + {g g}_{11} v v (({a a}_{1212} + + 11)) \\ - - {a a}_{21 twenty one} + + {g g}_{22} v v {a a}_{1111} & s the s - - {a a}_{22 twenty two} + + {g g}_{22} v v (({a a}_{1212} + + 11)) \end{matrix}|$

$= = {s the s}^{22} + + [[{g g}_{22} v v (({a a}_{1212} + + 11)) - - {a a}_{22 twenty two} - - {a a}_{1111} + + {g g}_{11} v v {a a}_{1111}]] s the s + + {a a}_{1111} {a a}_{22 twenty two} - - {a a}_{1212} {a a}_{21 twenty one}$

$+ + {g g}_{22} [[{a a}_{1212} v v {a a}_{1111} - - {a a}_{1111} v v (({a a}_{1212} + + 11))]] + + {g g}_{11} [[{a a}_{1212} v v (({a a}_{1212} + + 11)) - - {a a}_{1111} v v {a a}_{1212}]]$

$= = 00$

可以假设系统在稳定区域内的极点为s＝-pIt can be assumed that the poles of the system in the stable region are s=-p

对应特征方程为：The corresponding characteristic equation is:

f^*(s)＝(s+p)²＝s²+2ps+p²＝0f ^* (s)=(s+p) ² = ^s2 +2ps+ ^p2 =0

f(s)与f^*(s)对应待定系数得如下方程：f(s) and f ^* (s) correspond to undetermined coefficients as follows:

$\{\begin{matrix} {g g}_{22} v v (({a a}_{1212} + + 11)) - - {a a}_{22 twenty two} - - {a a}_{1111} + + {g g}_{11} v v {a a}_{1111} = = 22 p p \\ {a a}_{1111} {a a}_{22 twenty two} - - {a a}_{1212} {a a}_{21 twenty one} - - {g g}_{22} {a a}_{1111} v v + + {g g}_{11} [[{a a}_{1212} v v (({a a}_{1212} - - {a a}_{1111} + + 11))]] = = {p p}^{22} \end{matrix}$

解方程组可得到状态观测器的反馈增益矩阵GThe feedback gain matrix G of the state observer can be obtained by solving the equations

${g g}_{11} = = \frac{(({a a}_{1212} + + 11)) {p p}^{22} + + 22 {a a}_{1111} p p + + {a a}_{1111}^{22} + + {a a}_{1111} {a a}_{22 twenty two} + + {a a}_{1212} {a a}_{21 twenty one} + + {a a}_{1212}^{22} {a a}_{21 twenty one} - - {a a}_{1111} {a a}_{22 twenty two} - - {a a}_{1111} {a a}_{1212} {a a}_{22 twenty two}}{(({a a}_{1212}^{33} + + 22 {a a}_{1212}^{22} - - {a a}_{1111} {a a}_{1212}^{22} + + {a a}_{1111}^{22} - - {a a}_{1111} {a a}_{1212} + + {a a}_{1212})) v v}$

${g g}_{22} = = \frac{{a a}_{1111} {p p}^{22} - - 22 (({a a}_{1212}^{22} - - {a a}_{1111} {a a}_{1212} + + {a a}_{1212})) p p - - {a a}_{1111}^{22} {a a}_{22 twenty two} + + {a a}_{1111} {a a}_{1212} {a a}_{21 twenty one} - - {a a}_{1212}^{22} {a a}_{22 twenty two} - - {a a}_{1212} {a a}_{22 twenty two} + + {a a}_{1111} {a a}_{1212} {a a}_{22 twenty two} - - {a a}_{1111} {a a}_{1212}^{22} - - {a a}_{1111} {a a}_{1212} + + {a a}_{1111}^{22} {a a}_{1212}}{(({a a}_{1111} {a a}_{1212}^{22} + + {a a}_{1111} {a a}_{1212} - - {a a}_{1111}^{22} - - {a a}_{1212}^{44} - - 22 {a a}_{1212}^{33} - - {a a}_{1212}^{22})) v v}$

$G G = = [\begin{matrix} {g g}_{11} \\ {g g}_{22} \end{matrix}]$

反馈增益矩阵G根据系统传递函数的稳定区间内的极点来进行改变，达到系统现场稳定的要求。The feedback gain matrix G is changed according to the poles in the stable interval of the system transfer function to meet the requirements of the system's field stability.

本发明所设计的控制器如图4所示，主要包括以下几个部分：横摆角速度指令发生器、转矩分配控制器(TDC)、轮胎打滑控制器(WSC)，和状态观测器。当EPS失效时，通过检测方向盘9的转角或转矩而得到转向轮的转向角度δ_f，通过横摆角速度指令发生器得到预期的横摆角速度γ值，采用前馈和PI(比例积分)调节器调节使响应速度加快、动作准确，转矩分配控制器分配驱动转矩或制动转矩借助轮胎打滑控制器作用于车身，通过状态观测器检测γ，β值来组成闭环控制。The controller designed by the present invention is shown in Fig. 4, and mainly includes the following parts: a yaw rate command generator, a torque distribution controller (TDC), a tire slip controller (WSC), and a state observer. When the EPS fails, the steering angle _δf of the steering wheel is obtained by detecting the rotation angle or torque of the steering wheel 9, and the expected yaw rate γ value is obtained through the yaw rate command generator, which is adjusted by feedforward and PI (proportional integral) The controller adjusts to speed up the response and make the action accurate. The torque distribution controller distributes the driving torque or braking torque to act on the body with the help of the tire slip controller, and the state observer detects the γ and β values to form a closed-loop control.

当电动车转弯时，轮胎的方向与实际移动方向间有一定夹角：When the electric car turns, there is a certain angle between the direction of the tire and the actual moving direction:

${α α}_{f f} = = β β + + \frac{γ γ}{V V} {l l}_{f f} - - {δ δ}_{f f}$

提高电动车的操作性能的方法是尽量使电动车的前轮沿着导航角的方向前进，即尽量减小α_f。因此按照下述关系式：The way to improve the maneuverability of the electric vehicle is to make the front wheels of the electric vehicle advance along the direction of the navigation angle as far as possible, that is, to reduce α _f as much as possible. Therefore, according to the following relation:

γ^*＝(δ_f-β)v/l_f γ ^* ＝(δ _f -β)v/l _f

可以得到最佳横摆角速度指令值γ^*。The optimum yaw rate command value γ ^* can be obtained.

根据车体稳定所需要的旋转力矩大小，前后车轮组平均分配驱动力矩，左右车轮组互补分配转向力矩。具体的转矩分配控制器可以用如下方法实现：According to the size of the rotation torque required for the stability of the car body, the front and rear wheel groups evenly distribute the driving torque, and the left and right wheel groups complement each other to distribute the steering torque. The specific torque distribution controller can be realized by the following methods:

N＝N_f+N_r N=N _f +N _r

${N N}_{f f} = = \frac{d d}{22} (({F f}_{x x__fr fr} - - {F f}_{x x__fl fl})) = = \frac{11}{22} N N$

${N N}_{r r} = = \frac{d d}{22} (({F f}_{x x__rr rr} - - {F f}_{x x__rl rl})) = = \frac{11}{22} N N$

${F f}_{x x__fr fr} = = {F f}_{x x__fr fr}^{* *} + + \frac{N N}{22 d d}$

${F f}_{x x__fl fl} = = {F f}_{x x__fl fl}^{* *} - - \frac{N N}{22 d d}$

${F f}_{x x__rr rr} = = {F f}_{x x__rr rr}^{* *} + + \frac{N N}{22 d d}$

${F f}_{x x__rl rl} = = {F f}_{x x__rl rl}^{* *} - - \frac{N N}{22 d d}$

其中N_f是前车轮驱动力矩，N_r是后车轮驱动力矩，d是两轮间的距离。Among them, N _f is the driving torque of the front wheel, N _r is the driving torque of the rear wheel, and d is the distance between the two wheels.

或者采用只在前轮或后轮上进行转矩平均分配的方法。即Or use an even distribution of torque on the front or rear wheels only. Right now

$N_{f} = \frac{d}{2} (F_{x_fr} - F_{x_fl}) = N$ 或 $N_{r} = \frac{d}{2} (F_{x_rr} - F_{x_rl}) = N$ $N_{f} = \frac{d}{2} (f_{x_fr} - f_{x_fl}) = N$ or $N_{r} = \frac{d}{2} (f_{x_rr} - f_{x_rl}) = N$

驱动力或制动力经由车轮镇定控制器送到车轮上。车轮镇定控制器的工作原理是，构建一个负载观测器，让车轮按照车轮动力模型，根据驱动力指令值产生速度，即便在容易打滑的路面上，也会把打滑限制在允许范围内。车轮镇定控制器如图6所示，其闭环传递函数可以描述为：The driving force or braking force is sent to the wheels via the wheel stabilization controller. The working principle of the wheel stabilization controller is to build a load observer, so that the wheels can generate speed according to the driving force command value according to the wheel dynamic model. Even on slippery roads, the slip will be limited within the allowable range. The wheel stabilization controller is shown in Figure 6, and its closed-loop transfer function can be described as:

${G G}_{CL CL} = = \frac{(({τ τ}_{11} s the s + + 11)) (({τ τ}_{22} s the s + + 11))}{(({τ τ}_{11} s the s + + 11)) (({τ τ}_{22} s the s + + 11)) + + K K (({J J}_{n no} / / J J - - 11))}$

其中τ₁，τ₂是低通滤波器的时间常数，J_n折合到车轮上的全部转动惯量的额定值，J是车轮上的全部转动惯量的实际观测值 $J = T / {\overset{\cdot}{ω}}_{w} .$ Among them, τ ₁ and τ ₂ are the time constants of the low-pass filter, J _n is equivalent to the rated value of the total moment of inertia on the wheel, and J is the actual observed value of the total moment of inertia on the wheel $J = T / {\overset{\cdot}{ω}}_{w} .$

当J＝J_n时，闭环传递函数等于1；打滑发生时车体在车轮上的等效转动惯量就会减小，传递函数就会小于1，这样就减小了车轮的驱动转矩，从而抑制打滑的进一步发展。When J=J _n , the closed-loop transfer function is equal to 1; when slipping occurs, the equivalent moment of inertia of the car body on the wheel will decrease, and the transfer function will be less than 1, thus reducing the driving torque of the wheel, thereby Inhibits the further development of skids.

(参考文献Lianbing Li，Shinya Kodama，Yoichi Hori.Anti-Skid Control forEV Using Dynamic Model Error based on Back-EMF Observer.Proc.IECON 2004，Busan，Korea)。(Reference Lianbing Li, Shinya Kodama, Yoichi Hori. Anti-Skid Control for EV Using Dynamic Model Error based on Back-EMF Observer. Proc. IECON 2004, Busan, Korea).

通过判断扭矩传感器和横轴加速度变化的因果关系，可以判定EPS是否因故障而失效。By judging the causal relationship between the torque sensor and the change in the acceleration of the transverse axis, it can be determined whether the EPS has failed due to a fault.

在EPS发生故障失效的情况下，通过检测扭矩传感器的输出值，用如下公式推测驾驶员的转向角度指令值：In the case of EPS failure, by detecting the output value of the torque sensor, use the following formula to estimate the driver's steering angle command value:

${\overset{~ ~}{δ δ}}_{f f} = = K K \cdot \cdot {T T}_{S S}$

其中

是转向角度指令值的推测值，T_S是图7中扭矩传感器10的输出值17，K是把输出值17转换为转向角度指令值的推测值的比例系数，其大小为大于0，在0.035附近。in

is the estimated value of the steering angle command value, T _S is the output value 17 of the torque sensor 10 in Fig. nearby.

图8和图9是本发明的控制流程图。图8中，在EPS正常工作的情况下，通过检测扭矩传感器信号或从EPS的ECU中读取，获得一个适当的辅助转向力矩指令值，然后由力矩分配环节分配至各个车轮。并不对车身转向姿态进行闭环反馈。8 and 9 are control flow diagrams of the present invention. In Figure 8, when the EPS is working normally, an appropriate auxiliary steering torque command value is obtained by detecting the torque sensor signal or reading from the ECU of the EPS, and then distributed to each wheel by the torque distribution link. There is no closed-loop feedback on the steering attitude of the vehicle body.

图8的EPS故障失效情况和图9的两种情况，均采用车身转向姿态进行闭环反馈。The EPS fault failure situation in Figure 8 and the two situations in Figure 9 both use the body steering posture for closed-loop feedback.

本装置采用表1所示数据，采用日本尼桑系列，三月号(MARCH)车型，依据上述四轮车辆模型， $\overset{\cdot}{x} = Ax + Bu$ This device adopts the data shown in Table 1, adopts the Japanese Nissan series, the March issue (MARCH) model, and according to the above-mentioned four-wheel vehicle model, $\overset{&Center Dot;}{x} = Ax + Bu$

其中，in,

在摩擦系数为1.0的干燥柏油路面上进行计算机仿真测试，仿真结果如图10～12所示。A computer simulation test was carried out on a dry asphalt road with a friction coefficient of 1.0, and the simulation results are shown in Figures 10-12.

表1车辆仿真模型参数Table 1 Vehicle simulation model parameters

系统参数 System parameters 数值value 单位unit 车胎tire 半径rradius r 0.260.26 米 rice 转动惯量J_r Moment of inertia J _r 2.52.5 kgm² kgm ² 车轮阻力F_r Wheel resistance F _r 11*9.811*9.8 牛顿newton 减速比NgearReduction ratio Ngear 13.413.4 电机转矩系数C_T Motor torque coefficient C _T 0.21220.2122 车轮折算质量M_w Converted wheel mass M _w Jr/r/rJr/r/r 侧偏刚度C_fl，C_fr，C_rl，C_rr ^* Cornering stiffness C _fl , C _fr , C _rl , C _rr ^* 2.5×10⁴ 2.5×10 ⁴ 车身body 质量MQuality M 11001100 kgkg

全长l_all full length l _all 3.73.7 米 rice 转动惯量IMoment of inertia I kgm² kgm ² 重心到前轴距离l_f Center of gravity to front axle distance l _f 1.01.0 米 rice 重心到后轴距离l_r Distance from center of gravity to rear axle l _r 1.361.36 米 rice 前后轴距lFront and rear wheelbase l Lf+lrLf+lr 米 rice 前轮轴距d_f ^** Front wheelbase d _f ^** 1.361.36 米 rice 后轮轴距d_r ^** Rear wheelbase d _r ^** 1.331.33 米 rice 空气阻力F_a Air resistance F _a 0.5520.552 Ns²/m² Ns ² /m ² 其他初始参数Other initial parameters 车身初始速度V_initBody initial velocity V_init 1515 米/秒m/s 车轮初始速度Vw_initWheel initial speed Vw_init 1515 米/秒m/s 初始侧滑角β_initInitial sideslip angle β_init 00 radrad

初始横摆角速度γ_initInitial yaw rate γ_init 00 rad/secrad/sec

^*C_fl，C_fr，C_rl，C_rr取其平均值。 ^* Take the average value of C _fl , C _fr , C _rl , and C _rr .

^**前后轴距近似一致，因此取平均值，并均用d表示。 ^** The front and rear wheelbases are approximately the same, so the average value is taken and expressed in d.

图10是车辆重心轨迹仿真曲线。图10中I是不加本发明装置的车辆重心轨迹仿真曲线，由于转向控制精度低，响应有滞后，驾驶员多次修正轨迹，II是使用本分明装置后的车辆重心转向轨迹仿真曲线，曲线表明增加本装置后转向控制准确度改善。Fig. 10 is the simulation curve of the track of the center of gravity of the vehicle. Among Fig. 10, I is the simulation curve of the vehicle center of gravity track without adding the device of the present invention. Because the steering control precision is low, the response has a lag, and the driver corrects the track many times. II is the vehicle center of gravity steering track simulation curve after using the clear device, the curve It shows that the steering control accuracy is improved after adding the device.

图11是不带有本发明装置的EPS故障失效后的横摆角速度和转向曲线。III图是车速V和轮速V_w，IV图是横摆角，V图是横摆角速度，VI图是转向角度。VII图是车辆重心轨迹。Fig. 11 is the yaw rate and steering curves after the failure of the EPS without the device of the present invention. The figure III shows the vehicle speed V and the wheel speed V _w , the figure IV shows the yaw angle, the figure V shows the yaw rate, and the figure VI shows the steering angle. Figure VII is the trajectory of the center of gravity of the vehicle.

图12是带有本发明装置的EPS故障失效后的横摆角速度和转向轨迹曲线。VIII图是车速V和轮速V_w，IX图是横摆角，X图是横摆角速度，XI图是转向角度。XII图是车辆重心轨迹。Fig. 12 is the yaw rate and steering trajectory curves after the failure of the EPS with the device of the present invention. Graph VIII shows vehicle speed V and wheel speed V _w , graph IX shows yaw angle, graph X shows yaw rate, and graph XI shows steering angle. Figure XII is the locus of the vehicle's center of gravity.

图10表明EPS故障失效后不能转向。图12表明增加本发明装置后，EPS故障失效后仍能通过四轮转矩分配控制实现转向操作。Figure 10 shows that the steering cannot be turned after the EPS failure fails. Fig. 12 shows that after the device of the present invention is added, the steering operation can still be realized through the four-wheel torque distribution control after the EPS failure fails.

本发明是在电动助力转向系统EPS的基础上，通过对四轮制动力矩或驱动力矩的分配，辅助EPS转向或镇定车体动态，保证车辆2的安全控制。使汽车能在原有的EPS系统失效或EPS本身难以补偿由于路面和车况原因造成的转向不足和转向过度问题的情况下，驾驶员做出反应，通过检测方向盘9的转角或转矩得到转向轮的转向角度δ_f，通过横摆角速度指令发生器得到预期的γ值，通过状态观测器获得实际的横摆角速度γ和侧滑角β值，对横摆角速度通过转向动作的稳定控制的同时，输出四轮制动与驱动分配信号，采用前馈和PI调节器调节辅助转向转矩，通过转矩分配控制器将不同大小的驱动转矩或制动转矩分别加到各个车轮上，形成转向力矩，使转向响应速度加快、动作准确，实现EPS的故障安全功能。该系统不仅在EPS正常情况下能够保证车辆2的稳定运行，即使在EPS失效时也能保证汽车的正常转向。The present invention is based on the electric power steering system EPS, through the distribution of the four-wheel braking torque or driving torque, assists the EPS steering or stabilizes the dynamics of the vehicle body, and ensures the safety control of the vehicle 2 . When the original EPS system fails or the EPS itself is difficult to compensate for the understeer and oversteer problems caused by the road surface and vehicle conditions, the driver can respond by detecting the steering wheel 9 The angle or torque of the steering wheel is obtained. Steering angle δ _f , the expected γ value is obtained through the yaw rate command generator, and the actual yaw rate γ and sideslip angle β values are obtained through the state observer, while the yaw rate is stably controlled through the steering action, the output Four-wheel braking and driving distribution signals, using feedforward and PI regulators to adjust the auxiliary steering torque, and adding different driving torques or braking torques to each wheel through the torque distribution controller to form steering torque , so that the steering response speed is accelerated, the action is accurate, and the fail-safe function of EPS is realized. The system can not only ensure the stable operation of the vehicle 2 under normal EPS conditions, but also ensure the normal steering of the vehicle even when the EPS fails.

Claims

1. An electric power steering device, comprising:

Torque sensor, vehicle speed sensor, current sensor, control unit ECU, booster motor and deceleration mechanism; the steering wheel is connected with the torque sensor by the input shaft, and the torque sensor is also connected with the booster motor, and both the torque sensor and the booster motor are connected with the control unit ECU connection; characterized in that it also includes:

Wheel stabilization controller and four-wheel drive or braking torque control signal output device, the composition of the wheel stabilization controller is:

The yaw rate command generator is used to obtain the yaw rate command value;

State observer, used to obtain the actual yaw rate value and sideslip angle value;

The torque distribution controller adds different driving torques or braking torques to each wheel to form steering torque and speed up the steering response;

The tire slip controller improves the active safety performance of the vehicle by adjusting the force between the vehicle tire and the road surface;

The yaw rate command generator obtains the yaw rate command value γ by multiplying the difference between the steering angle δ _f of the steering wheel and the sideslip angle β by the speed v and then dividing by the distance l _f between the center of gravity and the steering wheel ^* .

2. The electric power steering device according to claim 1, characterized in that the torque distribution controller distributes the driving torque equally between the front and rear wheel groups, and the left and right wheel groups complement each other according to the size of the rotation torque required for vehicle body stability. Steering torque; or with an even distribution of torque on the front or rear wheels only.

3. The electric power steering device according to claim 1, characterized in that the tire slip controller calculates the acceleration and driving force signals based on the wheel speed, observes the equivalent moment of inertia of the vehicle body, and constructs an external disturbance signal observer, Thus forming a tire slip controller.

4. A method for controlling the electric power steering device according to claim 1, characterized in that it comprises the steps of:

1) Detect or read the steering wheel angle, and calculate the steering angle of the steering wheel;

2) Obtain the yaw rate command value through the vehicle body yaw rate command generator;

3) Obtain the actual body yaw rate and sideslip angle value through the state observer;

4) Use feedforward and PI regulators to adjust the steering assist torque, and add different driving torques or braking torques to each wheel through the torque distribution controller to form steering torque, so that the steering response speed is accelerated, Accurate movement;

5) The tire slip controller improves the active safety performance of the vehicle by adjusting the force between the vehicle tire and the road surface;

6) When the EPS fails, determine the steering angle δf desired by the driver by detecting the steering wheel angle or torque, adjust the driving torque or braking torque of each wheel, form the steering torque of the vehicle body, and force the vehicle body to turn according to the driver's control requirements , to realize the fail-safe function of EPS.

5. The control method according to claim 4, characterized in that the steering angle of the steering wheel or the command value of the steering assist torque is calculated through the torque sensor or the position sensor on the motor, or the steering angle value obtained from the control unit EUC.