A Stability Coordinated Control Method for a Drive System Containing a Hub Motor

Abstract

The present invention discloses a stability coordination control method for a drive system containing a wheel hub motor. The method obtains the instability degree parameter by obtaining the vehicle's center of mass side slip angle and yaw angular velocity, and divides the vehicle's stable state into a stable zone, a transition zone, and an instability zone according to the relationship between the instability degree parameter and the vehicle speed. When driving, the ESC controller allocates the drive system control tasks according to the instability degree parameter, the vehicle's stable state, and the tire adhesion, and allocates the drive system control tasks to itself / wheel hub motor controller / VCU. The method improves the robustness of vehicle stability control under extreme working conditions, fully utilizes the wheel hub motor controller to perform yaw control in the vehicle's linear zone, improves the steering response characteristics of the vehicle, and gives full play to the advanced nature of the wheel hub electric drive chassis.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle stability control, and in particular to a stability coordination control method for a drive system including a wheel hub motor. Background Art

[0002] Compared with traditional fuel vehicles, overdrive-by-wire electric vehicles have different power transmission systems. In-wheel motor drive technology also has more potential for electronic control and intelligent advantages due to its faster response speed, better control performance and higher control accuracy. Based on the above advantages, it is easier to achieve advanced chassis dynamics integrated control.

[0003] Based on the Any-Drive (front hub + rear hub) wheel hub electric drive chassis in the prior art, the TVCU can independently perform yaw stability control by utilizing the characteristics of the distributed drive electric vehicle motor torque response and independent torque control. The actuator of the TVCU (wheel hub motor controller) is the left / right rear wheel hub motor, which is the same as some actuators of the ESC system, and the TVCU will inevitably bring an additional yaw torque to the vehicle during control, which will affect the stability of the vehicle and even cause the vehicle to become unstable under some working conditions. Therefore, a stability coordination control method is required for the ESC and vehicle drive system (VCU+TVCU) to ensure the robustness of vehicle stability control.

[0004] To solve the above technical problems, the solution of the prior art 1 compensates the yaw rate through real-time differential of the rear wheels; however, the disadvantage of the prior art 1 is that it does not take into account the impact of the rear wheel hydraulic brake on the driving feel and comfort, and limits the ability of the front wheel steering, and does not consider the dynamic response of the vehicle under extreme working conditions. The solution of the prior art 2 independently distributes the driving torque of the distributed three motors through the TVCU to improve the vehicle's handling stability; the disadvantage of the prior art 2 is that it ignores the role of ESC in vehicle driving and does not consider the weight of hydraulic braking on the braking capacity of the entire vehicle. Summary of the invention

[0005] The object of the present invention is to provide a stability coordination control method for a drive system including a wheel hub motor, so as to enhance the robustness of the stability control of the whole vehicle.

[0006] In order to solve the above technical problems, the present invention provides a technical solution: a stability coordination control method for a drive system including a hub motor, wherein the drive system includes a front axle motor, a left rear hub motor, and a right rear hub motor. The method is enabled in a normal driving state of the vehicle and is executed by an ESC controller, and comprises the following steps:

[0007] Obtaining the vehicle's center of mass sideslip angle and yaw rate, and obtaining the instability degree parameter according to the center of mass sideslip angle and yaw rate;

[0008] The instability degree parameter is compared with the instability degree parameter setting threshold. If the instability degree parameter is greater than the instability degree parameter setting threshold, a yaw moment control command is sent to the front axle motor, the left rear wheel hub motor, the right rear wheel hub motor and the wheel cylinders of each wheel; if the instability degree parameter is less than the instability degree parameter setting threshold, the tire adhesion is obtained and the tire adhesion is compared with the tire adhesion setting threshold.

[0009] If the tire adhesion is greater than the set tire adhesion threshold, a yaw moment control command is sent to the front axle motor, left and right wheel hub motors, right rear wheel hub motor and each wheel brake cylinder; if the tire adhesion is less than the set tire adhesion threshold, the vehicle stability state is obtained according to the vehicle speed and instability degree parameters;

[0010] If the vehicle's stable state is in the stable zone, a VCU / wheel hub motor controller control mode activation command is sent to the VCU and wheel hub motor controller; if the vehicle's stable state is in the transition zone, a wheel hub motor controller control mode activation command is sent to the wheel hub motor controller; if the vehicle's stable state is in the unstable zone, a yaw moment control command is sent to the front axle motor, left and right wheel hub motors, right rear wheel hub motor and wheel cylinders of each wheel; the stable zone, transition zone and unstable zone are preset intervals.

[0011] According to the above scheme, the instability degree parameter is expressed as f(β, r), β is the eccentricity angle of the center of mass, r is the yaw angular velocity, and f(β, r) is specifically expressed as follows:

[0012] f(β, r) = qΔβ + (1-q)Δr

[0013] Among them, the value of q is as follows:

[0014]

[0015] In the above two equations, β1 and β2 are the upper limit and lower limit of the center of mass sideslip angle respectively obtained through experimental calibration; Δβ and Δr are the changes of the center of mass sideslip angle and the yaw angular velocity respectively.

[0016] According to the above scheme, after the VCU / wheel hub motor controller control mode activation instruction is sent to the VCU and the wheel hub motor controller, the VCU and the wheel hub motor controller enter the VCU / wheel hub motor controller control mode. In this control mode, the VCU performs the required torque distribution, and the VCU controls the front axle motor according to the required torque distribution result, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

[0017] According to the above scheme, after the VCU / wheel hub motor controller control mode activation instruction is sent to the VCU and the wheel hub motor controller, the VCU and the wheel hub motor controller enter the VCU / wheel hub motor controller control mode. In this control mode, the wheel hub motor controller performs the required torque distribution, and the VCU controls the front axle motor according to the required torque distribution result, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

[0018] According to the above scheme, after sending the hub motor controller control mode activation command to the hub motor controller, the hub motor controller enters the hub motor controller control mode. In this mode, the hub motor controller distributes the required torque, and the hub motor controller controls the left rear hub motor and the right rear hub motor according to the required torque distribution result.

[0019] According to the above scheme, the yaw moment control instruction includes a torque control instruction and a hydraulic control instruction, wherein the torque control instruction corresponds to the front axle motor, the left rear wheel hub motor, and the right rear wheel hub motor, and the hydraulic control instruction corresponds to the brake wheel cylinder of each wheel.

[0020] According to the above scheme, the preset interval is obtained by calibrating the instability degree parameters and vehicle speed in the experiment.

[0021] An ESC controller for stability coordination control, the ESC controller is used to execute the steps of the stability coordination control method of a drive system containing a hub motor as described above.

[0022] A stability coordination control system for a drive system containing a hub motor, the system comprising an ESC controller, a VCU and a hub motor controller; wherein the ESC is used to execute the steps of the stability coordination control method for a drive system containing a hub motor described above; the VCU is used to enable the VCU / hub motor controller control mode after receiving a VCU / hub motor controller control mode enable instruction; the hub motor controller is used to enable the VCU / hub motor controller control mode after receiving a VCU / hub motor controller control mode enable instruction, or to enable the hub motor controller control mode after receiving a hub motor controller control mode enable instruction.

[0023] A car, the driving system of which comprises a front axle motor, a left rear wheel hub motor and a right rear wheel hub motor, and the car is provided with a stability coordination control system of the driving system containing the wheel hub motor as described above.

[0024] The beneficial effects of the present invention are as follows: the instability degree parameter is calculated by obtaining the vehicle's center of mass side slip angle and yaw angular velocity, and the vehicle's stable state is divided into a stable zone, a transition zone, and an unstable zone according to the relationship between the instability degree parameter and the vehicle speed. When driving, the ESC controller allocates the drive system control task according to the instability degree parameter, the vehicle's stable state, and the tire adhesion. The method utilizes the ESC controller to monitor and take over the drive system in real time, enhances the robustness of the vehicle stability control under extreme working conditions, and utilizes the wheel hub motor controller in the linear zone (stable zone and transition zone) for yaw control, thereby improving the steering response characteristics of the vehicle and giving full play to the advanced nature of the wheel hub electric drive chassis. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flow chart of a stability coordination control method of a drive system including a hub motor according to a first embodiment of the present invention;

[0026] Figure 2 is a curve diagram showing the relationship between the weight coefficient q and |β| in the first embodiment of the present invention;

[0027] Figure 3 is a schematic diagram of dividing vehicle stable states according to the first embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of tire adhesion judgment according to the first embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0030] Embodiment 1:

[0031] See also Figure 1 A stability coordination control method for a drive system including a hub motor, wherein the drive system includes a front axle motor, a left rear hub motor, and a right rear hub motor. The method is enabled in a normal driving state of the vehicle and is executed by an ESC controller, and comprises the following steps:

[0032] Obtaining the vehicle's center of mass sideslip angle and yaw rate, and obtaining the instability degree parameter according to the center of mass sideslip angle and yaw rate;

[0033] The instability degree parameter is compared with the instability degree parameter setting threshold. If the instability degree parameter is greater than the instability degree parameter setting threshold, a yaw moment control command is sent to the front axle motor, the left rear wheel hub motor, the right rear wheel hub motor and the wheel cylinders of each wheel (the generation of the yaw moment control command is the same as the conventional ESC control method in the prior art, which will not be described in detail here); if the instability degree parameter is less than the instability degree parameter setting threshold, the tire adhesion is obtained and the tire adhesion is compared with the tire adhesion setting threshold for judgment;

[0034] If the tire adhesion is greater than the tire adhesion setting threshold, the yaw moment control command is sent to the front axle motor, left and right wheel hub motors, right rear wheel hub motor and each wheel brake cylinder; if the tire adhesion is less than the tire adhesion setting threshold, the vehicle stability state is obtained according to the vehicle speed and instability degree parameters (see the tire adhesion judgment method for details). Figure 4 , Figure 4 The horizontal and vertical axes in the figure represent the lateral and longitudinal adhesion of the tire, respectively. The largest circle represents the maximum adhesion that the tire can achieve, and the smaller red circle represents the set threshold of the tire adhesion. xi w is the axial distance from the horizontal axis where the longitudinal force of the wheel reaches the limit of the tire adhesion circle boundary, yi is the longitudinal axial distance at which the lateral force of the wheel reaches the boundary limit of the tire adhesion circle); f(w i ) is the function for calculating the weight coefficient, and defines f(w i )as follows:

[0035]

[0036] Where z is the given tire force stability range, such as Figure 4 As shown in the smaller red circle. i )>0, the wheel is considered to have reached its adhesion limit.

[0037] If the vehicle is in a stable state, a VCU / wheel hub motor controller control mode activation command is sent to the VCU and wheel hub motor controller; if the vehicle is in a transitional state, a wheel hub motor controller control mode activation command is sent to the wheel hub motor controller; if the vehicle is in an unstable state, a yaw moment control command is sent to the front axle motor, the left and right wheel hub motors, the right rear wheel hub motor and the wheel cylinders of each wheel; the stable zone, transition zone and unstable zone are pre-calibrated according to the instability degree parameters and vehicle speed in the test (see Figure 3 , V x is vehicle speed).

[0038] Further, see Figure 2, the instability parameter is expressed as f(β, r), β is the mass center eccentricity angle, r is the yaw rate [the mass center eccentricity angle and yaw rate of the vehicle have a significant impact on the vehicle's operational stability, so the size of the two needs to be strictly controlled during vehicle operation to prevent vehicle instability, and there is a coupling effect between the two, so when calculating the instability parameter f(β, r), it is necessary to perform weighted joint control of the two], f(β, r) is specifically expressed as follows,

[0039] f(β, r) = qΔβ + (1-q)Δr

[0040] See also Figure 2 , where the weight coefficient q is taken as follows:

[0041]

[0042] In the above two equations, β1 and β2 are the upper limit and lower limit of the center of mass sideslip angle respectively obtained through experimental calibration; Δβ and Δr are the changes of the center of mass sideslip angle and the yaw angular velocity respectively.

[0043] Furthermore, after sending the VCU / wheel hub motor controller control mode activation instruction to the VCU and the wheel hub motor controller, the VCU and the wheel hub motor controller enter the VCU / wheel hub motor controller control mode, in which the VCU performs the required torque distribution, the VCU controls the front axle motor according to the required torque distribution result, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

[0044] Further, after sending the wheel hub motor controller control mode activation instruction to the wheel hub motor controller, the wheel hub motor controller enters the wheel hub motor controller control mode, in which the wheel hub motor controller performs the required torque distribution, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

[0045] Furthermore, the yaw moment control instruction includes a torque control instruction and a hydraulic control instruction, wherein the actuators corresponding to the torque control instruction are the front axle motor, the left rear wheel hub motor, and the right rear wheel hub motor, and the actuators corresponding to the hydraulic control instruction are the brake wheel cylinders of each wheel.

[0046] The technical effects produced by this embodiment include improved driving comfort and safety; in terms of driving comfort, the steering response characteristics of the car in the linear region are improved, and the advanced nature of the hub electric drive chassis is fully utilized; in terms of safety, the robustness of the vehicle stability control is improved to prevent false triggering of functions.

[0047] Embodiment 2:

[0048] The difference between this embodiment and the first embodiment is that after sending the VCU / wheel hub motor controller control mode activation instruction to the VCU and the wheel hub motor controller, the VCU and the wheel hub motor controller enter the VCU / wheel hub motor controller control mode, in which the wheel hub motor controller performs the required torque distribution, the VCU controls the front axle motor according to the required torque distribution result, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

[0049] Embodiment three:

[0050] An ESC controller for stability coordination control, the ESC controller is used to execute the steps of the stability coordination control method of a drive system containing a hub motor described in embodiment 1 or embodiment 2.

[0051] Embodiment three:

[0052] A stability coordination control system for a drive system containing a hub motor, the system comprising an ESC controller, a VCU and a hub motor controller; wherein the ESC is used to execute the steps of the stability coordination control method for a drive system containing a hub motor described in Example 1 or Example 2; the VCU is used to enable the VCU / hub motor controller control mode after receiving a VCU / hub motor controller control mode enable instruction; the hub motor controller is used to enable the VCU / hub motor controller control mode after receiving a VCU / hub motor controller control mode enable instruction, or enable the hub motor controller control mode after receiving a hub motor controller control mode enable instruction.

[0053] Embodiment 4:

[0054] A car, the driving system of which comprises a front axle motor, a left rear wheel hub motor and a right rear wheel hub motor, the car being provided with a stability coordination control system of the driving system comprising the wheel hub motor as described in the third embodiment.

[0055] Embodiment five:

[0056] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the stability coordination control method of a drive system containing a hub motor as described in Embodiment 1 or Embodiment 2.

[0057] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A stability coordination control method for a drive system including a hub motor, characterized in that: The drive system includes a front axle motor, a left rear wheel hub motor, and a right rear wheel hub motor. The method is enabled when the vehicle is in normal driving state and is executed by an ESC controller, and includes the following steps: Obtaining the vehicle's center of mass sideslip angle and yaw rate, and obtaining the instability degree parameter according to the center of mass sideslip angle and yaw rate; The instability degree parameter is compared with the instability degree parameter setting threshold. If the instability degree parameter is greater than the instability degree parameter setting threshold, a yaw moment control command is sent to the front axle motor, the left rear wheel hub motor, the right rear wheel hub motor and the wheel cylinders of each wheel; if the instability degree parameter is less than the instability degree parameter setting threshold, the tire adhesion is obtained and the tire adhesion is compared with the tire adhesion setting threshold. If the tire adhesion is greater than the set tire adhesion threshold, a yaw moment control command is sent to the front axle motor, left and right wheel hub motors, right rear wheel hub motor and each wheel brake cylinder; if the tire adhesion is less than the set tire adhesion threshold, the vehicle stability state is obtained according to the vehicle speed and instability degree parameters; If the vehicle is in a stable state, a VCU / wheel hub motor controller control mode activation command is sent to the VCU and wheel hub motor controller; if the vehicle is in a transitional state, a wheel hub motor controller control mode activation command is sent to the wheel hub motor controller; if the vehicle is in an unstable state, a yaw moment control command is sent to the front axle motor, left and right wheel hub motors, right rear wheel hub motor and wheel cylinders of each wheel; the stable zone, transition zone and unstable zone are preset intervals; The instability degree parameter is expressed as f(β,r), β is the eccentricity angle of the center of mass, and r is the yaw angular velocity. The specific expression of f(β,r) is as follows: f(β,r)=qΔβ+(1-q)Δr Among them, the value of q is as follows: Among them, β1 and β2 are the upper limit and lower limit of the center of mass sideslip angle obtained through experimental calibration; Δβ and Δr are the changes of the center of mass sideslip angle and the yaw rate respectively; The preset interval is obtained by calibrating the instability degree parameter and the vehicle speed in the experiment.

2. The stability coordination control method of a drive system including a hub motor according to claim 1, characterized in that: After sending the VCU / wheel hub motor controller control mode enable command to the VCU and wheel hub motor controller, the VCU and wheel hub motor controller enter the VCU / wheel hub motor controller control mode. In this control mode, the VCU performs the required torque distribution, and the VCU controls the front axle motor according to the required torque distribution result, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

3. The stability coordination control method of a drive system including a hub motor according to claim 1, characterized in that: After sending the VCU / wheel hub motor controller control mode enable command to the VCU and wheel hub motor controller, the VCU and wheel hub motor controller enter the VCU / wheel hub motor controller control mode. In this control mode, the wheel hub motor controller performs the required torque distribution. The VCU controls the front axle motor according to the required torque distribution result, and the wheel hub motor controller controls the left rear wheel hub motor and the right rear wheel hub motor according to the required torque distribution result.

4. The stability coordination control method of a drive system including a hub motor according to claim 1, characterized in that: After sending the hub motor controller control mode activation command to the hub motor controller, the hub motor controller enters the hub motor controller control mode, in which the hub motor controller performs the required torque distribution, and the hub motor controller controls the left rear hub motor and the right rear hub motor according to the required torque distribution result.

5. The stability coordination control method of a drive system including a hub motor according to claim 1, characterized in that: The yaw moment control instruction includes a torque control instruction and a hydraulic control instruction, wherein the torque control instruction corresponds to the front axle motor, the left rear wheel hub motor, and the right rear wheel hub motor, and the hydraulic control instruction corresponds to the brake wheel cylinder of each wheel.

6. An ESC controller for stability coordinated control, characterized in that: The ESC controller is used to execute the steps of the stability coordination control method of a drive system containing a hub motor as described in any one of claims 1-5.

7. A stability coordination control system for a drive system including a hub motor, characterized in that: The system includes an ESC controller, a VCU and a hub motor controller; wherein the ESC is used to execute the steps of the stability coordination control method of a drive system containing a hub motor as described in any one of claims 1-5; the VCU is used to enable the VCU / hub motor controller control mode after receiving a VCU / hub motor controller control mode enable instruction; the hub motor controller is used to enable the VCU / hub motor controller control mode after receiving a VCU / hub motor controller control mode enable instruction, or to enable the hub motor controller control mode after receiving a hub motor controller control mode enable instruction.

8. A car, characterized in that: The driving system of the automobile comprises a front axle motor, a left rear wheel hub motor, and a right rear wheel hub motor. The automobile is provided with a stability coordination control system of the driving system comprising the wheel hub motor as claimed in claim 7.

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