System and method for independently controlling wheel slip and vehicle acceleration

• US 9,988,026 B2
• Filed: 12/22/2015
• Issued: 06/05/2018
• Est. Priority Date: 12/22/2015
• Status: Active Grant

• Current Assignee: Veoneer Nissin Brake Systems Japan Co., Ltd.
• Original Assignee: Autoliv Nissin Brake Systems Japan Co., Ltd. (Autoliv Incorporated)
• Inventors: Ying, Long
• Primary Examiner(s): Black, Thomas G
• Assistant Examiner(s): Lewandroski, Sara J
• Application Number:
  US14/977,919
• Publication Number:
  US 20170174192A1
• Time in Patent Office: 896 Days
• CPC Class Codes: B60T 2250/04 Vehicle reference speed; Vehicle body speed
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B60T 8/1761 responsive to wheel or brake dynamics, e.g. wheel slip, wheel acceleration or rate of change of brake fluid pressure
• CPC Class Codes: B60T 8/17616 Microprocessor-based systems
• CPC Class Codes: B60T 8/1766 Proportioning of brake forces according to vehicle axle loads, e.g. front to rear of vehicle
• CPC Class Codes: B60T 8/58 responsive to speed and another condition or to plural speed conditions
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 30/18 Propelling the vehicle
• CPC Class Codes: B60W 30/18172 Preventing, or responsive to skidding of wheels

Abstract

The present disclosure relates to a system for real time control of a wheel slip of each slipping wheel of a pair of wheels associated with an axle of a motor vehicle, simultaneously and independently with real time explicit control of said motor vehicle'"'"'s acceleration provided by each non-slipping wheel associated with the axle. The system makes use of a total controller and an asymmetric controller associated with the axle of the vehicle for generating two torque signals used to control the total and asymmetric dynamics respectively of the axle, and a distributor for distributing the two said torque signals into available actuators'"'"' targets. The two said controllers each contain feedback and feed forward control elements, is operable to sense wheel slippage condition of each wheel on the axle, and augments the feedback and feed forward control based on the sensed wheel slippage conditions.

Claims

1. A system for real time control of a wheel slip of each one of a pair of wheels associated with a first axle of a motor vehicle, simultaneously and independently with real time explicit control of an acceleration of said motor vehicle provided by each non-slipping one of the pair of wheels, the system comprising:

a coordinated wheel controller (CWC) subsystem having;

a first total controller associated with the first axle of the vehicle for generating a torque signal (T_TC) used to control total dynamics of the first axle; and

a first asymmetric controller associated with the first axle, which is operable to generate another torque signal (T_AC) to control asymmetric dynamics of the first axle;

the first total controller and the first asymmetric controller each further configured to include;

a wheel slip feedback control mode; and

a feed forward control mode;

the feed forward control mode enabling the controllers to induce changes in a specific wheel'"'"'s surface torque (T_S), and therefore influence vehicle acceleration;

the first total controller and the first asymmetric controller each further configured to detect a real time operating condition of each said wheel which includes a wheel slip condition and a wheel non-slip condition, and to augment the respective wheel slip feedback control mode and the feed forward control mode associated with each said controller, the augmentation being based on the detected operating condition of each said wheel and a pre-defined table of conditions; and

a distributor subsystem used for generating a drive torque target (T_D) if a drive train of the motor vehicle is associated with the first axle and the torque signal is controllable, and further generating a brake torque target for a left wheel (T_BL) and a brake torque target for a right wheel (T_BR) associated with the first axle, in response to the torque signal (T_TC) and the another torque signal (T_AC) of the CWC subsystem and in a manner such that the following equations are satisfied;

2. The system of claim 1, wherein the predefined table of conditions comprises conditions set forth in Table 1 of FIG. 7 hereof.

3. The system of claim 1, further comprising a direct torque management (DTM) subsystem having:

a DTM wheel control module for calculating the desired rate of change of a surface torque experienced by each wheel whenever each said wheel is operating in a stable operating region and not experiencing wheel slip.

4. The system of claim 3, wherein the DTM subsystem further includes a DTM motion control handling module for calculating the another desired change of a surface torque experienced by each wheel in response to torque commands of an external system on each said wheel, whenever each said wheel is operating in a stable operating region and not experiencing wheel slip.

5. The system of claim 4, wherein the DTM subsystem further comprises a DTM arbiter module responsive to the DTM wheel control module and to the DTM motion control handling module, the DTM arbiter module being configured to arbitrate the outputs from the DTM wheel control module and the DTM motion control handling module which relate to the rate of change of surface torque for each one of the wheels which is operating in a non-slipping operating region, and

then for the DTM arbiter module to calculate rates of change of surface torque outputs (dT_TC and dT_AC) from the first total controller and the first asymmetric controller, respectively, of the CWC subsystem that are required to induce arbitrated rates of change of surface torques for the two wheels (dT_SL and dT_SR).

6. The system of claim 1, further comprising an initialization and saturation module for performing calculations needed to support the initialization and a reset of a controller of the CWC subsystem when system saturation is detected.

7. The system of claim 1, further comprising a control deviation subsystem configured to detect when each said wheel is slipping on a ground surface and when each said wheel is stable and not slipping on a ground surface.

8. The system of claim 7, wherein the control deviation subsystem is further configured to:

transform wheel speed targets for each of the wheels to axle total and axle symmetric targets;

transform individual wheel speed feedback associated with each of the wheels to axle total and axle symmetric feedback values; and

to calculate an axle total and an axle asymmetric control deviation value.

9. The system of claim 1, wherein the vehicle includes a second axle, and the system further comprises:

a second total controller operably associated with the second axle; and

a second asymmetric controller operably associated with the second axle;

both the second total controller and the second asymmetric controller configured identically to the first total controller and the first asymmetric controller, including having identical support from the distributor subsystem.

10. A system for real time control of a wheel slip of each one of a pair of slipping wheels associated with a first axle of a motor vehicle, simultaneously and independently with real time explicit control of an acceleration of said motor vehicle provided by a non-slipping one of the pair of wheels, the system comprising:

a control deviation module for determining whether either said wheel is slipping or stable and non-slipping, and for calculating a total control deviation and a total asymmetric control deviation of said axle;

a direct torque management (DTM) subsystem for controlling a surface torque of each of the wheels;

a coordinated wheel controller (CWC) subsystem having;

a first total controller associated with the first axle of the vehicle for generating a torque signal (T_TC) used to control total dynamics of the first axle;

a first asymmetric controller associated with the first axle, which is operable to generate another torque signal (T_AC) to control asymmetric dynamics of the first axle;

and each of said first total controller and said first asymmetric controller configured to implement a feed forward mode in which each is able to induce changes in a specific wheel'"'"'s surface torque (T_S), and therefore to influence vehicle acceleration;

the direct torque management (DTM) subsystem operating to determine a rate of change of surface torque outputs from each of the first total controller (dT_TC) and the first asymmetric controller (dT_TC) that are required to induce a desired rate of change of the surface torque for each said wheel (dT_SL and dT_SR); and

a distributor subsystem responsive to the CWC subsystem for generating a drive torque target T_D if a drive train of the motor vehicle is associated with the first axle and drive train is controllable, and for generating a brake torque target for a left wheel (T_BL) and for a right wheel (T_BR) each wheel associated with the first axle, in response to torque signal (T_TC) and the another torque signal (T_AC) from the CWC subsystem.

11. The system of claim 10, wherein the control deviation module generates the axle total control deviation and axle asymmetric control deviation by:

first transforming

12. The system of claim 10, wherein the DTM subsystem comprises:

a DTM wheel control module for calculating the desired rate of change of a surface torque experienced by each wheel whenever each said wheel is operating in a stable operating region and not experiencing wheel slip;

13. The system of claim 10, wherein the first total controller of the CWC subsystem is further configured to include:

a wheel slip feedback control mode, which is configured to apply a feedback control to a total control deviation of the first axle (V_{Dev_TC}) which is calculated by the control deviation module;

a feed forward control mode, which is configured to pass along the rate of change of surface torque output (dT_TC) of the first axle which is calculated by the DTM subsystem; and

configured to calculate and output a surface torque signal (T_TC) by augmenting the wheel slip feedback control mode and the feed forward control modes, wherein the augmentation is based on

     1) a status of each wheel on the first axle that is calculated by the control deviation module and

     2) a predetermined strategy given by a table, where {dot over (ω

)}_A represents asymmetric dynamics;

14. The system of claim 10, wherein the first asymmetric controller of the CWC subsystem is further configured to include:

a wheel slip feedback control mode, which is configured to apply a feedback control to a asymmetric control deviation of the first axle (V_{Dev_AC}) which is calculated by the control deviation module;

a feed forward control mode, which is configured to pass along the rate of change of surface torque output (dT_AC) of the first axle which is calculated by the DTM subsystem; and

configured to calculate and output a torque signal (T_AC) by augmenting the wheel slip feedback control mode and the feed forward control modes, wherein the augmentation is based on

     1) a status of each wheel on the first axle that is detected by the control deviation module and

     2) a predetermined strategy given by a table, where T_BL represents brake torque for a left wheel of the wheel pair, where T_BR represents brake torque for a right wheel of the wheel pair, and where {dot over (ω

)}_A is asymmetric dynamics;

15. The system of claim 10, wherein the distributor subsystem is configured to calculate the drive torque target T_D and brake torque targets (T_BL and T_BR) for the first axle in response to the CWC subsystem'"'"'s output signals (T_TC and T_AC), in a manner such that the following equations are satisfied:

16. The system of claim 10, for a second axle of the motor vehicle, further comprising:

a second total controller operably associated with the second axle; and

a second asymmetric controller operably associated with the second axle;

both the second total controller and the second asymmetric controller configured identically to the first total controller and the first asymmetric controller, including having support from the control deviation module, the direct torque management subsystem, and the distributor subsystem.

17. A method for real time control of a pair of wheels associated with a first axle of a motor vehicle, wherein one of the pair of wheels is slipping, simultaneously and independently with real time explicit control of an acceleration of said motor vehicle provided by one wheel of the pair of wheels that is non-slipping and associated with the first axle, the method comprising:

using a first total controller associated with the first axle of the vehicle to generate a torque signal output (T_TC);

using a first asymmetric controller associated with the first axle to generate another torque signal output (T_AC) by detecting a real time operating condition of each said wheel which includes a wheel slip condition and a wheel non-slip condition, and

augmenting the first total controller and a wheel slip feedback control mode and a feed forward control mode of the first asymmetric controller, the augmentation being based on the detected operating condition of each said wheel and a pre-defined table of conditions; and

using a distributor subsystem used to generate a drive torque target T_D and a brake torque target, the brake torque target being for a left wheel (T_BL) and for a right wheel T_BR) associated with the first axle, in response to the first total controller and torque signal outputs of the first asymmetric controller (T_TC and T_AC), in a manner such that the following equations are satisfied;

18. The method of claim 17, wherein the predefined table comprises Table 1 of FIG. 7 hereof.

19. The method of claim 17, further comprising using the direct torque management (DTM) subsystem to calculate, for use as inputs to the feed forward control modes of the first total controller and the first asymmetric controller, a rate of change of surface torque output (dT_TC) and a rate of change of torque output (dT_AC) from the first total controller and the first asymmetric controller, respectively by:

using a DTM wheel control module to calculate the desired rate of change of a surface torque experienced by each wheel corresponding to a desired change of vehicle acceleration provided by each said wheel, whenever each said wheel is operating in a stable operating region and not experiencing wheel slip;

using a DTM motion control handling module to calculate another desired change of a surface torque experienced by each wheel in response to torque commands of an external system on each said wheel, whenever each said wheel is operating in a stable operating region and not experiencing wheel slip;

then using a DTM arbiter module to arbitrate outputs from the DTM wheel control module and DTM motion control handling module into a final rate of change of surface torque for each one of the wheels (dT_SL and dT_SR) which is operating in a non-slipping operating region; and

then applying a formula;