Vehicle driving force control method

• US 20050038588A1
• Filed: 08/14/2003
• Published: 02/17/2005
• Est. Priority Date: 08/14/2003
• Status: Abandoned Application

• Current Assignee: USGI Medical, Inc., Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: USGI Medical, Inc.
• Inventors: Shukla, Deepak
• Application Number:
  US10/641,411
• Publication Number:
  US 20050038588A1
• Time in Patent Office: Days
• US Class Current: 701/70
• CPC Class Codes: B60T 2210/12 Friction
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02

Abstract

A method of controlling the wheel speed of a vehicle wheel supported by a surface to achieve a desired vehicle acceleration, desired yaw rate or a desired vehicle velocity. The method receives sensor readings indicative of a vehicle state and operator input. From the received sensor readings a current wheel speed and a desired wheel speed are determined. A torque is applied to the wheel to correct for any wheel speed error, the difference between the desired wheel speed and the current wheel speed. To determine the amount of torque that may be applied to the vehicle wheel while preventing the wheel from slipping, a friction coefficient between the wheel and the surface may be determined.

Claims

1. A method of controlling the wheel speed of a vehicle wheel supported by a surface, said method comprising:

receiving a first and second sensor reading indicative of a vehicle state;

determining a current wheel speed from said first sensor reading;

determining a desired wheel speed from said second sensor reading;

determining a wheel speed error based on the difference between said desired wheel speed and said current wheel speed;

determining a torque to be applied to the vehicle wheel from said wheel speed error.

2. The method of claim 1 further including the steps of:

determining a friction coefficient between the wheel and the surface;

determining a current wheel torque using said desired wheel speed, said sensor readings and said friction coefficient;

determining a maximum torque that may be applied without slip of the vehicle wheel;

ensuring that the sum of said torque to be applied and said current torque is less than or approximately equal to said maximum torque.

3. The method of claim 1 further comprising the step of determining a vehicle velocity and wherein the step of determining said current wheel speed is based on said determined vehicle velocity.

4. The method of claim 3 wherein said step of determining a desired wheel speed includes the step of determining a desired vehicle acceleration.

5. The method of claim 3 wherein said step of determining a desired wheel speed further includes the step of determining a desired vehicle velocity.

6. The method of claim 5 wherein said desired vehicle velocity further includes the step of determining a vehicle acceleration.

7. The method of claim 3 wherein said step of determining a desired wheel speed includes the step of determining a desired yaw rate.

8. The method of claim 7 wherein said step of calculating a wheel speed error further includes the step of calculating a yaw rate error.

9. The method of claim 1 wherein said first sensor reading is a vehicle wheel speed and said second sensor reading is indicative of an operator input.

10. The method of claim 1 wherein said torque to be applied (T) is defined by:

T=I{dot over (ω

)}_d+RF_z{circumflex over (μ

)}_d(λ

_d)+K₁e+K₂ρ

²e

11. The method of claim 10 wherein the vehicle includes a left rear wheel and a right rear wheel, and wherein the step of determining a desired wheel speed is based on desired wheel speed for the left rear wheel (ω

_d,RL) which is defined by;

$\begin{array}{c}{\mathrm{\omega <br><br>}}_{d,\mathrm{RL}}=<br><br>\frac{v_x-b<br><br>\text{\hspace{1em}<br><br>}<br><br>r_d}{R_{\mathrm{RL}}}+\\ <br><br>{\widetilde{\mathrm{\omega <br><br>}}}_{d,\mathrm{RL}}<br><br>{❘<br><br>}_{t=0}<br><br>+{\mathrm{e<br><br>}}^{-k_{\mathrm{RL}}<br><br>t}<br><br>{\int <br><br>}_0^t<br><br>{\mathrm{e<br><br>}}^{k_{\mathrm{RL}}<br><br>t}<br><br>\left(k_{\mathrm{RL}}·<br><br>g<br><br>\left({\widehat{\mathrm{\mu <br><br>}}}_L^{\mathrm{\prime <br><br>}}\right)·<br><br>h<br><br>\left(\frac{e_v-b<br><br>\text{\hspace{1em}<br><br>}<br><br>e_r}{R_{\mathrm{RL}}}\right)\right)<br><br>d<br><br>t\end{array}$

12. The method of claim 10 wherein the vehicle includes a left rear wheel and a right rear wheel, and wherein the step of determining a desired wheel speed is based on said desired wheel speed for the right rear wheel (ω

_d,RR) which is defined by;

$\begin{array}{c}{\mathrm{\omega <br><br>}}_{d,\mathrm{RR}}=<br><br>\frac{v_x-b<br><br>\text{\hspace{1em}<br><br>}<br><br>r_d}{R_{\mathrm{RR}}}+{\widetilde{\mathrm{\omega <br><br>}}}_{d,\mathrm{RR}}<br><br>{❘<br><br>}_{t=0}+\\ <br><br>{\mathrm{e<br><br>}}^{-k_{\mathrm{RR}}<br><br>t}<br><br>{\int <br><br>}_0^t<br><br>{\mathrm{e<br><br>}}^{k_{\mathrm{RR}}<br><br>t}<br><br>\left(k_{\mathrm{RL}}·<br><br>g<br><br>\left({\widehat{\mathrm{\mu <br><br>}}}_L^{\mathrm{\prime <br><br>}}\right)·<br><br>h<br><br>\left(\frac{e_v-b<br><br>\text{\hspace{1em}<br><br>}<br><br>e_r}{R_{\mathrm{RR}}}\right)\right)<br><br>d<br><br>t\end{array}$

13. A method of controlling the wheel speed of a vehicle wheel supported by a surface, said method comprising:

receiving a sensor reading indicative of a vehicle travel state;

receiving a sensor reading indicative of operator input;

determining a desired yaw rate from said sensor readings indicative of a vehicle travel state and said sensor readings indicative of operator input;

determining a current wheel speed;

determining a desired wheel speed using said desired yaw rate;

calculating a wheel speed error based on the difference between said desired wheel speed and said current wheel speed;

determining an applied torque to be applied to the vehicle wheel from said wheel speed error.

14. The method of claim 13 further comprising the step of calculating a current vehicle velocity from said received sensor readings indicative of a vehicle travel state.

15. The method of claim 13 wherein the vehicle includes a left rear wheel and a right rear wheel, and wherein said step of determining said desired wheel speed includes the step of calculating a nominal desired velocity for each of the left and right wheels of the vehicle.

16. The method of claim 13 wherein said step of determining an applied torque includes the steps of mapping a hysteresis characteristic and mapping a dead band characteristic.

17. The method of claim 13 wherein said sensor reading indicative of operator input is a steering wheel angle signal.

18. A method of controlling the wheel speed of a vehicle wheel supported by a surface, said method comprising:

receiving sensor readings indicative of a vehicle travel state;

receiving sensor readings indicative of operator input;

determining a desired acceleration from said sensor readings indicative of a vehicle travel state and said sensor readings indicative of operator input;

determining a current wheel speed of the vehicle wheel;

determining a desired wheel speed of the vehicle wheel from said desired acceleration;

calculating a wheel speed error, said wheel speed error being the difference between said desired wheel speed and said current wheel speed;

determining an applied torque to be applied to the vehicle wheel from said wheel speed error.

19. The method of claim 18 further comprising the step of calculating a vehicle velocity from said sensor readings indicative of a vehicle travel state.

20. The method of claim 18 wherein said desired acceleration (α

_x,d) is defined by;

α

_x,d=H_th(s)f(x_th,v_x)−

k_brx_brsgn(v_x)−

k_v|v_x|−

k_α

v_x²