A control method and system for a vehicle

Abstract

The present application relates to the technical field of vehicle control, more particularly to a control method and system of vehicle.The control method of vehicle provided by the present application comprises the following steps: calculating a reference wheel speed according to an actually obtained wheel speed and a body inertia measurement unit signal; judging whether the vehicle wheel is slipping or locked according to the calculated reference wheel speed; if the vehicle wheel is slipping or locked, calculating a target motor speed according to the reference wheel speed; and performing closed-loop control on the motor speed to drive the motor to reach the target motor speed.The control method and system of vehicle provided by the present application can control the target motor speed by precisely regulating the torque, thereby realizing excellent vehicle anti-slip and anti-lock functions and providing strong guarantee for driving safety.

Description

Technical Field

[0001] This invention relates to the field of vehicle control technology, and more specifically, to a vehicle control method and system. Background Technology

[0002] In today's context of pursuing both environmental protection and energy efficiency, electric vehicles are gaining increasing popularity as a crucial component of future sustainable transportation. However, compared to traditional internal combustion engine vehicles, electric vehicles are more prone to slippage or engine lock-up during driving. This phenomenon primarily stems from the fact that the torque characteristics of the electric motor, the drive source of electric vehicles, differ significantly from those of traditional internal combustion engine engines.

[0003] Electric vehicle motors have significantly higher torque than internal combustion engine motors. This high torque gives electric vehicles unparalleled power performance during start-up and acceleration, allowing them to quickly increase speed. However, this powerful torque also brings a significant problem: electric vehicles are more prone to slippage or lock-up.

[0004] When the motor's torque is transmitted to the wheels, it must balance the torque exerted on the wheels by the ground. This balance is achieved through the friction between the tire and the ground. However, when the motor's torque T is too large, or the coefficient of friction of the ground (i.e., the coefficient of friction between the tire and the ground) is too small, this balance is broken. In this case, the motor's torque T will exceed F*r (where F is the friction force exerted by the ground on the wheel, and r is the radius of the wheel), causing the wheel to accelerate rapidly, resulting in slippage or wheel lock-up.

[0005] Slippage or wheel lock-up not only affects a vehicle's acceleration performance but also severely impacts its stability and safety. According to tire dynamics, as wheel speed increases rapidly, the tire's slip ratio changes accordingly. The slip ratio is a measure of the ratio of the tire's actual speed to the wheel's rotational speed, reflecting the relative motion between the tire and the ground. At a higher slip ratio, the friction between the tire and the ground decreases significantly, resulting in a corresponding reduction in the lateral force the wheel can provide (i.e., the force that resists lateral movement of the vehicle).

[0006] This reduction in lateral force directly leads to a decrease in the vehicle's lateral stability. In situations such as high-speed driving or emergency turns, insufficient lateral stability can easily lead to dangerous situations such as skidding or loss of control, endangering not only the lives of the driver and passengers but also posing a serious safety hazard to road traffic.

[0007] Therefore, how to control the vehicle to solve the problem of slippage or lock-up in electric vehicles has become a serious challenge. Summary of the Invention

[0008] The purpose of this invention is to provide a vehicle control method and system that solves the problem of poor control over slippage or lock-up of electric vehicles in existing automobiles.

[0009] To achieve the above objectives, the present invention provides a vehicle control method, comprising the following steps:

[0010] The reference wheel speed is calculated based on the actual wheel speed, motor speed, and vehicle body inertial measurement unit signals.

[0011] Based on the calculated reference wheel speed, determine whether the vehicle wheels are slipping or locked.

[0012] If the vehicle wheels slip or lock up, the target motor speed is calculated based on the reference wheel speed.

[0013] The motor speed is controlled in a closed loop to drive the motor to the target speed.

[0014] In some embodiments, the closed-loop control of the motor speed further includes the following steps:

[0015] The required drive torque is calculated based on the accelerator pedal opening.

[0016] Based on the calculated drive torque, the target torque of the motor is calculated.

[0017] Based on the target torque of the motor, the torque boundary of the motor is limited when controlling the speed of the motor.

[0018] In some embodiments, calculating the reference wheel speed further includes:

[0019] Establish a slope estimation model;

[0020] The reference wheel speed is calculated based on the slope estimation model, which considers the influence of slope on the signal of the vehicle body inertial measurement unit.

[0021] In some embodiments, establishing the slope model further includes:

[0022] Based on the height sensor installed on the suspension, the slope deviation introduced by the front and rear pitch of the suspension is corrected.

[0023] In some embodiments, the slope estimation model includes a kinematic model and / or a dynamic model:

[0024] The kinematic model is implemented based on the kinematic rules governing the changes in speed and acceleration of a vehicle on a slope;

[0025] The dynamic model is implemented based on the dynamic rules of longitudinal force, acceleration, and velocity of the vehicle on the slope.

[0026] In some embodiments, the calculation of the reference wheel speed based on the slope estimation model, which considers the influence of slope on the vehicle body inertial measurement unit signal, further includes:

[0027] The slope value of the current road is obtained based on the slope estimation model;

[0028] The longitudinal acceleration value of the vehicle is calculated based on the longitudinal acceleration signal from the vehicle body inertial measurement unit and the acceleration data caused by gravity due to slope.

[0029] In some embodiments, calculating the reference wheel speed further includes:

[0030] Based on the lateral and longitudinal acceleration signals at the vehicle's center of gravity detected by the vehicle body inertial measurement unit, and combined with the wheel speed, the reference wheel speed is calculated.

[0031] In some embodiments, the method for calculating the reference wheel speed further includes:

[0032] Simplify the vehicle into a rigid body model;

[0033] The specific values ​​of lateral acceleration, longitudinal acceleration, and yaw rate at a certain position of the rigid body are obtained by detecting the vehicle body inertial measurement unit.

[0034] Based on the kinematics of rigid bodies, the acceleration value at the wheel position point is calculated.

[0035] In some embodiments, determining whether the vehicle wheels slip or lock up based on the calculated reference wheel speed further includes:

[0036] Set up a Kalman filter estimator and use the actual wheel speed signal, the lateral acceleration, longitudinal acceleration and yaw rate of the vehicle body inertial measurement unit as the observed values;

[0037] Based on wheel speed, lateral acceleration, longitudinal acceleration, and yaw rate, determine whether the wheel is slipping or has a tendency to lock up;

[0038] Adjust the confidence level of the Kalman filter estimator observations based on the tendency of the wheels to slip or lock up;

[0039] Calculate the reference wheel speed based on the estimate from the Kalman filter estimator;

[0040] If the difference between the actual wheel speed and the reference wheel speed is greater than the first preset limit, it is determined that the wheel has slipped.

[0041] If the difference between the actual wheel speed and the reference wheel speed is less than the second preset limit, it is determined that the wheel has locked up.

[0042] In some embodiments, calculating the target motor speed based on the reference wheel speed further includes:

[0043] Based on the reference wheel speed of each wheel, combined with the target slip ratio, the target motor speed of the drive motor is converted according to the drive type.

[0044] In some embodiments, if the drive form is a combination of a single motor and a mechanical differential as the drive shaft, the speed of the target motor is calculated by the left wheel speed, the right wheel speed, the differential transmission ratio, and the reducer transmission ratio.

[0045] If the drive type is a distributed drive shaft, the target motor speed is calculated by the vehicle speed of the corresponding wheel and the gear ratio of the reducer.

[0046] In some embodiments, the closed-loop control of the motor speed to drive the motor to the target motor speed further includes:

[0047] Adjust the target torque of the motor to track and control the motor speed;

[0048] Set the adjustment range limit for the target torque of the motor to ensure that the direction of the target torque remains unchanged compared with before the adjustment and that the magnitude of the torque does not exceed the torque command value set before the adjustment.

[0049] To achieve the above objectives, the present invention provides a vehicle control system for implementing the vehicle control method described above, comprising a vehicle controller and a motor controller:

[0050] The vehicle controller calculates a reference wheel speed based on the wheel speed and the vehicle body inertial measurement unit signal; it determines whether the vehicle wheels are slipping or locking based on the calculated reference wheel speed; if the vehicle wheels slip or lock, it calculates the target motor speed based on the reference wheel speed.

[0051] The motor controller performs closed-loop control of the motor speed, driving the motor to reach the target motor speed.

[0052] To achieve the above objectives, the present invention provides a vehicle control system, including a motor controller:

[0053] The motor controller is used to implement the control method of the vehicle described above.

[0054] To achieve the above objectives, the present invention provides a vehicle control system, including an engine controller:

[0055] The engine controller is used to implement the control method for the vehicle described above.

[0056] The present invention proposes a vehicle control method and system that precisely regulates torque to control the target motor speed, thereby achieving excellent vehicle anti-skid and anti-lock braking functions and providing strong protection for driving safety. Attached Figure Description

[0057] The above-described and other features, properties, and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, in which the same reference numerals consistently denote the same features.

[0058] in:

[0059] Figure 1 A flowchart illustrating a vehicle control method according to an embodiment of the present invention is disclosed;

[0060] Figure 2 A schematic diagram of a vehicle control system according to an embodiment of the present invention is disclosed;

[0061] Figure 3 A flowchart of a vehicle control method according to an embodiment of the present invention is disclosed;

[0062] Figure 4 A schematic diagram illustrating slope estimation according to an embodiment of the present invention is shown;

[0063] Figure 5 A schematic diagram of suspension correction according to an embodiment of the present invention is disclosed;

[0064] Figure 6 A flowchart for determining vehicle slippage or lockup according to an embodiment of the present invention is disclosed;

[0065] Figure 7 A schematic diagram of a Kalman filter algorithm according to an embodiment of the present invention is disclosed;

[0066] Figure 8 The diagram shows the anti-slip control effect based on traditional methods;

[0067] Figure 9 A diagram illustrating the anti-slip control effect according to an embodiment of the present invention is shown.

[0068] The meanings of the labels in the figures are as follows:

[0069] 100 controller;

[0070] 210 First Motor Controller;

[0071] 220 Second Motor Controller;

[0072] 300 vehicle body inertial measurement unit. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0074] Figure 1 A flowchart illustrating a vehicle control method according to an embodiment of the present invention is disclosed. Figure 2 A schematic diagram of a vehicle control system according to an embodiment of the present invention is disclosed, such as... Figure 1 and Figure 2 As shown, the present invention proposes a vehicle control method, which includes the following steps:

[0075] Step S1: Calculate the reference wheel speed based on the actual wheel speed, motor speed, and vehicle body inertial measurement unit signal;

[0076] Step S2: Based on the calculated reference wheel speed, determine whether the vehicle wheels are slipping or locked.

[0077] Step S3: If the vehicle wheels slip or lock up, calculate the target motor speed based on the reference wheel speed;

[0078] Step S4: Perform closed-loop control on the motor speed to drive the motor to the target motor speed.

[0079] like Figure 2 As shown, the controller 100 acquires wheel speed data for all four wheels, including the first, second, third, and fourth wheel speeds. It also acquires lateral and longitudinal acceleration data, as well as yaw acceleration data, from the vehicle body inertial measurement unit 300. Based on this data, the controller 100 calculates the target motor speed.

[0080] During the control process, wheel slippage or lockup may occur. To effectively address this situation, once the controller 100 detects wheel slippage or lockup, it will adjust the required torque in real time. Specifically, the controller 100 will send a first target motor torque and a first target motor speed to the first motor controller 210, and a second target motor torque and a second target motor speed to the second motor controller 220. The first motor controller 210 and the second motor controller 220 perform closed-loop control of the motor speed to ensure that wheel slippage or lockup remains within a reasonable range.

[0081] It should be clarified that the configuration of the vehicle body inertial measurement unit 300 and the controller 100 can be flexibly selected. They can exist independently or be integrated into one unit, and there are no specific restrictions on this.

[0082] Figure 3 A flowchart of a vehicle control method according to an embodiment of the present invention is disclosed below, which will be combined with Figures 1 to 3 These steps will be described in detail below. It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with and related to each other to form preferred technical solutions.

[0083] Step S1: Calculate the reference wheel speed based on the actual wheel speed, motor speed, and vehicle body inertial measurement unit signal.

[0084] The reference wheel speed can be calculated based on the wheel speed, motor speed, and the IMU (Inertial Measurement Unit) signal of the vehicle body.

[0085] Furthermore, the gradient can be estimated based on the wheel speed and the vehicle's IMU signal, and this gradient is also included in the calculation of the reference wheel speed.

[0086] Figure 4 A schematic diagram illustrating slope estimation according to an embodiment of the present invention is shown, such as... Figure 4 As shown, the calculation of the reference wheel speed further includes:

[0087] Establish a slope estimation model;

[0088] Based on the slope estimation model and considering the influence of slope on the vehicle body inertial measurement unit signal, the reference wheel speed is calculated.

[0089] The slope estimation model includes kinematic and / or dynamic models. Kinematic models primarily focus on the relationship between an object's motion state (position, velocity, acceleration) and its attitude (including slope), typically neglecting the object's mass, forces, and torques. Dynamic models, on the other hand, involve the forces and torques of the object during its motion, considering the influence of the slope on these factors.

[0090] In this embodiment, the kinematic model is implemented based on the kinematic rules governing the changes in the vehicle's velocity and acceleration on a slope, and the corresponding state variable expressions are as follows:

[0091] a(k+1) = a(k);

[0092] v(k+1)=v(k)+a(k)*dT;

[0093] z(k+1) = z(k);

[0094] Where a(k) is the acceleration at time k, v(k) is the velocity at time k, z(k) is the slope at time k, and dT is the discretization time.

[0095] In this embodiment, the dynamic model is implemented based on the dynamic rules of the vehicle's longitudinal force, acceleration, and velocity on the slope, and the corresponding state variable expressions are as follows:

[0096] a(k+1)=F / mg*z(k);

[0097] v(k+1)=v(k)+a(k)*dT;

[0098] z(k+1) = z(k);

[0099] Where a(k) is the acceleration at time k, v(k) is the velocity at time k, z(k) is the slope at time k, F is the longitudinal force on the vehicle, m is the mass of the vehicle, and g is the gravitational acceleration.

[0100] like Figure 4 As shown, if the vehicle is on a slope, the longitudinal acceleration sensor of the IMU (Inertial Measurement Unit) will inevitably be affected by the gravitational component on the slope. Therefore, in order to accurately calculate the reference wheel speed, this influence needs to be corrected. The specific steps further include:

[0101] First, the slope value of the current road is obtained based on the slope estimation model;

[0102] Subsequently, by combining the longitudinal acceleration signal Ax_sensor from the vehicle body inertial measurement unit with the acceleration data gsinθ caused by the slope gravity, the longitudinal acceleration value ax of the vehicle is calculated.

[0103] Where, Ax_sensor = ax + gsinθ.

[0104] This step aims to separate the influence of slope on acceleration measurements from the total measured values, thereby more accurately reflecting the vehicle's true motion. In other words, it is necessary not only to estimate the road slope value, but also to subtract the additional acceleration component caused by this slope value when calculating the vehicle's longitudinal acceleration.

[0105] Furthermore, in order to further improve the accuracy and reliability of the data and prevent potential interference from noise signals to the final results, this invention employs Kalman filtering technology to effectively process and optimize the data.

[0106] Figure 5 A schematic diagram illustrating suspension correction according to an embodiment of the present invention is shown, such as... Figure 5 As shown, when the vehicle is pitching forward or backward, the slope estimation result will inevitably be biased. In order to accurately reflect the actual slope, necessary corrections need to be made based on the height sensor installed on the suspension, thereby eliminating the slope deviation introduced by the forward and backward pitch of the suspension.

[0107] Based on the lateral and longitudinal acceleration signals detected at a specific location on the vehicle by the vehicle body inertial measurement unit (IMU), and combined with wheel speed information, a reference wheel speed can be calculated. In this embodiment, the specific location on the vehicle is the vehicle's center of gravity.

[0108] Specifically, in order to effectively determine whether wheel slippage is occurring, the vehicle's current reference wheel speed must first be estimated. During this process, the controller can use the IMU to acquire lateral and longitudinal acceleration signals at the vehicle's center of gravity, and combine this with wheel speed data acquired by the wheel speed sensors. By comprehensively analyzing these signals, the vehicle's reference wheel speed can be estimated.

[0109] When calculating the reference wheel speed of a vehicle, the vehicle can be simplified into a rigid body model. The specific values ​​of the lateral acceleration, longitudinal acceleration, and yaw rate at the center of mass of this rigid body model can be obtained through an IMU. Based on the kinematic principles of rigid bodies, the acceleration values ​​at the wheel positions can be calculated.

[0110] Step S2: Based on the calculated reference wheel speed, determine whether the vehicle wheels are slipping or locked.

[0111] Figure 6 A flowchart for determining vehicle slippage or lockup according to an embodiment of the present invention is disclosed. Figure 7 A schematic diagram of a Kalman filtering algorithm according to an embodiment of the present invention is disclosed, as follows: Figure 6 and Figure 7 As shown, the step of determining whether the vehicle wheels slip or lock up based on the calculated reference wheel speed further includes:

[0112] Set up a Kalman filter estimator and use the actual wheel speed signal, the lateral acceleration, longitudinal acceleration and yaw rate of the vehicle body inertial measurement unit as the observed values;

[0113] Based on wheel speed, lateral acceleration, longitudinal acceleration, and yaw rate, determine whether the wheel is slipping or has a tendency to lock up;

[0114] Adjust the confidence level of the Kalman filter estimator observations based on the tendency of the wheels to slip or lock up;

[0115] Calculate the reference wheel speed based on the estimate from the Kalman filter estimator;

[0116] If the difference between the actual wheel speed and the reference wheel speed is greater than the first preset limit, it is determined that the wheel has slipped.

[0117] If the difference between the actual wheel speed and the reference wheel speed is less than the second preset limit, it is determined that the wheel has locked up.

[0118] Furthermore, based on the reference wheel speed and the actual wheel speed, if the difference between the wheel speed and the reference wheel speed is greater than the limit, it is determined that the wheel is prone to slipping or locking up.

[0119] The Kalman filter estimator is a highly efficient recursive filter (autoregressive filter) that can estimate the state of a dynamic system from a series of measurements containing statistical noise. In the field of vehicle control, Kalman filtering is widely used for vehicle speed estimation, vehicle state prediction, and other applications.

[0120] Step S3: If the vehicle wheels slip or lock up, calculate the target motor speed based on the reference wheel speed.

[0121] Based on the vehicle's reference wheel speed and target slip ratio, the target motor speed is converted into the drive motor speed according to the differential model, thus achieving closed-loop control of the motor speed. Slip ratio is an indicator that measures the degree of relative slippage between the wheel and the ground, describing the difference between the wheel's actual motion state and its theoretical rolling state.

[0122] Furthermore, the calculation of the target motor speed based on the reference wheel speed further includes:

[0123] Based on the reference wheel speed of each wheel, the target motor speed of the drive motor is converted according to the drive type.

[0124] If the drive configuration is a combination of a single motor and a mechanical differential as the drive shaft, the target motor speed is calculated by taking the left wheel speed, the right wheel speed, the differential gear ratio, and the reducer gear ratio together.

[0125] The specific formula is: Target motor speed = (left wheel speed + right wheel speed) * differential gear ratio * reducer gear ratio / 2;

[0126] If the drive type is a distributed drive shaft, the target motor speed is calculated by the vehicle speed of the corresponding wheel and the gear ratio of the reducer.

[0127] The specific formula is: Target motor speed = Corresponding wheel speed * Reducer transmission ratio.

[0128] Step S4: Perform closed-loop control on the motor speed to drive the motor to the target motor speed.

[0129] During the process of controlling the motor speed, the target torque value of the motor, which is calculated by the driver based on the input of the accelerator pedal, will be dynamically adjusted.

[0130] Specifically, the closed-loop control of the motor speed also includes the following steps:

[0131] Drive torque calculation: Calculate the required drive torque based on the accelerator pedal opening;

[0132] Target torque calculation: Based on the calculated drive torque, the target torque of the motor is calculated.

[0133] Speed ​​tracking control: Based on the target torque of the motor, the motor is controlled to keep the actual motor speed tracking the target motor speed, and the torque boundary of the motor is limited when controlling the motor speed.

[0134] During the speed tracking process, the motor will adjust its target torque in a timely manner according to the actual operating conditions to ensure that the actual speed can be accurately tracked and stabilized at the target speed.

[0135] Furthermore, the target torque of the motor is adjusted to track and control the motor speed;

[0136] Set the adjustment range limit for the target torque of the motor to ensure that the direction of the target torque remains unchanged compared with before the adjustment and that the magnitude of the torque does not exceed the torque command value set before the adjustment.

[0137] It should be noted that, as Figure 2 The "Controller 100" shown does not refer to a specific hardware device, but rather an important component of the software control strategy. In practical applications, it can be various types of controllers, such as a vehicle controller, a motor control unit (MCU), or an engine control system (EMS), depending on the vehicle's design and configuration.

[0138] Although the methods described above are illustrated and depicted as a series of actions for the sake of simplicity, it should be understood and appreciated that these methods are not limited by the order of the actions, as some actions may occur in a different order and / or concurrently with other actions from the illustrations and descriptions herein or not illustrated and described herein but which may be understood by those skilled in the art, according to one or more embodiments.

[0139] The scope of powertrain products encompasses vehicle controllers, engine controllers, and motor controllers. Based on the aforementioned powertrain products, this invention proposes three vehicle control systems with unique functional architectures, aiming to realize the aforementioned vehicle control methods.

[0140] Based on the above vehicle control method, the first vehicle control system proposed in this invention includes a vehicle controller and a motor controller:

[0141] The vehicle controller calculates a reference wheel speed based on the wheel speed and the vehicle body inertial measurement unit signal; it determines whether the vehicle wheels are slipping or locking based on the calculated reference wheel speed; if the vehicle wheels slip or lock, it calculates the target motor speed based on the reference wheel speed.

[0142] The motor controller performs closed-loop control of the motor speed, driving the motor to reach the target motor speed.

[0143] Based on the above vehicle control method, the second vehicle control system proposed in this invention includes a motor controller:

[0144] The motor controller is used to implement the vehicle control method described above.

[0145] In the second type of vehicle control system, the motor controller plays a crucial role, fully realizing the vehicle's anti-skid or anti-lock braking control functions and ensuring safety and stability during driving.

[0146] Based on the above vehicle control methods, the present invention proposes a third vehicle control system, including an engine controller:

[0147] The engine controller is used to implement the vehicle control method described above.

[0148] The vehicles targeted by this invention are not limited to a specific number of wheels, nor are they limited to electric vehicles or gasoline-powered vehicles.

[0149] The specific working details of the vehicle control system correspond to the aforementioned vehicle control methods, so the specific details will not be repeated here.

[0150] The vehicle control method and system proposed in this invention are not limited to a specific motor or engine arrangement, but include, but are not limited to, power configurations such as engine configuration, single motor configuration, front and rear dual motor configuration, and distributed four-motor configuration.

[0151] Specifically, in the engine configuration, all the functions of the present invention are deployed in the engine controller, which constitutes the third vehicle control system of the present invention.

[0152] For a single-motor configuration, there are two deployment schemes: one is to deploy the target speed calculation function in the vehicle controller, while the motor speed control function is deployed in the motor controller. This scheme is the first vehicle control system proposed in this invention. The other is to deploy all functions in the motor controller. This scheme constitutes the second vehicle control system of this invention.

[0153] The deployment methods for both front and rear dual-motor configurations and distributed four-motor configurations follow the deployment principle of single-motor configurations, that is, selecting appropriate control units for functional deployment based on specific circumstances.

[0154] The following section uses the first vehicle control system proposed in this invention as an example to explain in detail the actual effect of its functional control.

[0155] Figure 8The diagrams reveal the anti-slip control effect based on traditional methods, such as... Figure 8 As shown, the traditional method achieves control of the vehicle's anti-slip function through the coordinated action of the electronic stability control system, vehicle controller, and motor controller. Curve 81 represents the actual rotational speed of the drive wheels, while curve 82 reflects the actual rotational speed of the non-drive wheels. Observation clearly shows that when drive wheel slippage occurs, although torque adjustment measures can reduce the severity of slippage to some extent, a slippage state of approximately 0.5 seconds still exists, and the slip ratio remains at a relatively high level.

[0156] Figure 9 A diagram illustrating the anti-slip control effect according to an embodiment of the present invention is shown, such as... Figure 9 As shown, curve 91 represents the actual rotational speed of the drive wheels, while curve 92 reflects the actual rotational speed of the non-drive wheels. The vehicle control system proposed in this invention significantly improves the efficiency and effectiveness of anti-slip control. Specifically, in the initial stage of drive wheel slippage, i.e., within 0.1 seconds after slippage begins, the system can effectively eliminate wheel slippage, and the slip ratio is maintained at a relatively low level.

[0157] The present invention proposes a vehicle control method and system that achieves excellent vehicle anti-skid and anti-lock braking functions by precisely adjusting torque to control the target motor speed, thereby providing a strong guarantee for driving safety.

[0158] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" are not specifically singular and may include plural forms. Generally speaking, the terms "comprising" and "including" only indicate the inclusion of explicitly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements.

[0159] The above embodiments are provided for those skilled in the art to implement or use the present invention. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited to the above embodiments, but should be the maximum scope that conforms to the innovative features mentioned in the claims.

Claims

1. A method for controlling a vehicle, characterized in that, Includes the following steps: The reference wheel speed is calculated based on the actual wheel speed, motor speed, and vehicle body inertial measurement unit signals. Based on the calculated reference wheel speed, determine whether the vehicle wheels are slipping or locked. If the vehicle wheels slip or lock up, the target motor speed is calculated based on the reference wheel speed. Closed-loop control of motor speed is implemented to drive the motor to the target motor speed; The calculation of the reference wheel speed further includes: Based on the lateral and longitudinal acceleration signals detected at a certain position of the vehicle by the vehicle body inertial measurement unit, and combined with the wheel speed, the reference wheel speed is calculated. The method for calculating the reference wheel speed further includes: Simplify the vehicle into a rigid body model; The specific values ​​of lateral acceleration, longitudinal acceleration, and yaw rate at a certain position of the rigid body are obtained by detecting the vehicle body inertial measurement unit. Based on the kinematics of rigid bodies, the acceleration value at the wheel position point is calculated; The step of determining whether the vehicle wheels are slipping or locked based on the calculated reference wheel speed further includes: Set up a Kalman filter estimator and use the actual wheel speed signal, the lateral acceleration, longitudinal acceleration and yaw rate of the vehicle body inertial measurement unit as the observed values; Based on wheel speed, lateral acceleration, longitudinal acceleration, and yaw rate, determine whether the wheel is slipping or has a tendency to lock up.

2. The vehicle control method according to claim 1, characterized in that, The closed-loop control of the motor speed also includes the following steps: The required drive torque is calculated based on the accelerator pedal opening. Based on the calculated drive torque, the target torque of the motor is calculated. Based on the target torque of the motor, the torque boundary of the motor is limited when controlling the speed of the motor.

3. The vehicle control method according to claim 1, characterized in that, The calculation of the reference wheel speed also includes: Establish a slope estimation model; The reference wheel speed is calculated based on the slope estimation model, which considers the influence of slope on the signal of the vehicle body inertial measurement unit.

4. The vehicle control method according to claim 3, characterized in that, The slope estimation model includes a kinematic model and / or a dynamic model: The kinematic model is implemented based on the kinematic rules governing the changes in speed and acceleration of a vehicle on a slope; The dynamic model is implemented based on the dynamic rules of longitudinal force, acceleration, and velocity of the vehicle on the slope.

5. The vehicle control method according to claim 3, characterized in that, The slope estimation model, which considers the influence of slope on the vehicle body inertial measurement unit signal and calculates the reference wheel speed, further includes: The slope value of the current road is obtained based on the slope estimation model; The longitudinal acceleration value of the vehicle is calculated based on the longitudinal acceleration signal from the vehicle body inertial measurement unit and the acceleration data caused by gravity due to slope.

6. The vehicle control method according to claim 3, characterized in that, The establishment of the slope estimation model further includes: The slope deviation introduced by the front and rear pitch of the suspension is corrected based on the height sensor installed on the suspension.

7. The vehicle control method according to claim 1, characterized in that, The step of determining whether the vehicle wheels are slipping or locked based on the calculated reference wheel speed further includes: Adjust the confidence level of the Kalman filter estimator observations based on the tendency of the wheels to slip or lock up; Calculate the reference wheel speed based on the estimate from the Kalman filter estimator; If the difference between the actual wheel speed and the reference wheel speed is greater than the first preset limit, it is determined that the wheel has slipped. If the difference between the actual wheel speed and the reference wheel speed is less than the second preset limit, it is determined that the wheel has locked up.

8. The vehicle control method according to claim 1, characterized in that, The step of calculating the target motor speed based on the reference wheel speed further includes: Based on the reference wheel speed of each wheel, combined with the target slip ratio, the target motor speed of the drive motor is converted according to the drive type.

9. The vehicle control method according to claim 8, characterized in that, If the drive form is a combination of a single motor and a mechanical differential as the drive shaft, the speed of the target motor is calculated by the speed of the left wheel, the speed of the right wheel, the transmission ratio of the differential, and the transmission ratio of the reducer. If the drive type is a distributed drive shaft, the target motor speed is calculated by the vehicle speed of the corresponding wheel and the gear ratio of the reducer.

10. The vehicle control method according to claim 1, characterized in that, The method of performing closed-loop control of the motor speed to drive the motor to the target motor speed further includes: Adjust the target torque of the motor to track and control the motor speed; Set the adjustment range limit for the target torque of the motor to ensure that the direction of the target torque remains unchanged compared with before the adjustment and that the magnitude of the torque does not exceed the torque command value set before the adjustment.

11. A vehicle control system for implementing the vehicle control method as described in any one of claims 1 to 10, characterized in that, This includes the vehicle controller and the motor controller: The vehicle controller calculates a reference wheel speed based on the wheel speed and the vehicle body inertial measurement unit signal; it determines whether the vehicle wheels are slipping or locking based on the calculated reference wheel speed; if the vehicle wheels slip or lock, it calculates the target motor speed based on the reference wheel speed. The motor controller performs closed-loop control of the motor speed, driving the motor to reach the target motor speed.

12. A vehicle control system, characterized in that, Including the motor controller: The motor controller is used to implement the vehicle control method as described in any one of claims 1 to 10.

13. A vehicle control system, characterized in that, Including the engine controller: The engine controller is used to implement the vehicle control method as described in any one of claims 1 to 10.

Images