Wheel imbalance rejection module

Patent metadata

Field	Value
Publication number	US-9862411-B2
Application number	US-201514812221-A
Country	US
Kind code	B2
Filing date	Jul 29, 2015
Priority date	Jul 30, 2014
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A control system and method for a hydraulic-power steering system of a vehicle including magnetic torque overlay (MTO) is provided. The control system and method minimize undesirable vibration in a handwheel of the vehicle as a result of disturbance in its front road wheels (e.g., road-wheel imbalance). In the control system and method, a base torque command is determined or generated. At least the base torque command is passed to a disturbance-rejection module. The disturbance-rejection module modifies the base torque command to minimize the vibration.

First claim

Having thus described the invention, it is claimed:

1. A control method of reducing vibration in a handwheel of a magnetic torque overlay (MTO) steering system, the method comprising:
providing a base torque command, a left wheel speed signal associated with a left road wheel, right wheel speed signal associated with a right road wheel, a handwheel angular position signal, and an estimation of torque signal to a wheel imbalance rejection (WIR) module for generation of a final torque command by modifying the base torque command based at least in-part by comparing the left and right wheel speed signals to determine a wheel imbalance between the left and right road wheels and to identify a force of disturbance attributable from the left and right wheel speed signals and thereby generate the final torque command; and
controlling the MTO steering system to generate a desired assist torque based on the final torque command.

2. The control method set forth in claim 1 , further comprising:
providing the left and right wheel speed signals to respective first and second wheel speed conversion and filter modules of the WIR module configured to respectively output first and second unfiltered radian signals, and first, and second filtered signals having units of frequency toward generation of the final torque command.

3. The control method set forth in claim 2 , further comprising:
averaging the first and second filtered signals to generate an averaged filtered signal toward generation of the final torque command.

4. The control method set forth in claim 3 , further comprising:
passing the averaged filtered signal, the base torque command, and the estimation of torque signal to a notch filter of the WIR module to generate a notched torque command toward generation of the final torque command.

5. The control method set forth in claim 4 , further comprising:
passing the first and second filtered signals, the first and second radian signals, the averaged filtered signal, and the handwheel angular position signal to a subsystem of the WIR module for generating a subsystem output command; and
summing the subsystem output command with the notched torque command to generate the final torque command.

6. The control method set forth in claim 5 , further comprising:
establishing coefficients for a unity gain resonance filter of the notch filter from the averaged filtered signal; and
locating a pole at a wheel imbalance frequency for a current operating speed and the base torque command is run through the unity gain resonance filter to extract content at the wheel imbalance frequency thereby generating a filtered torque command.

7. The control method set forth in claim 6 , further comprising:
passing the averaged filtered signal and estimation of torque signal to a notch filter gain module of the notch filter to generate a gain value;
multiplying the filtered torque command by the gain value to generate an adjusted-filtered torque command; and
subtracting the adjusted-filtered torque command from the base torque command to generate the notched torque command.

8. The control method set forth in claim 7 , further comprising:
applying a frequency scaled table of the notch filter gain module to the averaged filtered signal to generate;
filtering the estimation of torque signal to generate a filtered value;
applying a torque scaled table of the notch filter gain module to the filtered value; and
enabling the notch filter when both the averaged filtered signal and the filtered value are within a desired range as reflected via the respective frequency and torque scaled tables.

9. The control method set forth in claim 1 , further comprising:
providing a vehicle speed signal, the estimation of torque signal, the handwheel angular position signal, and a differential pressure signal outputted by an MTO steering assist unit into a torque-command module for generation of the base torque command.

10. The control method set forth in claim 1 , further comprising:
converting the final torque command expressed in units of torque to a current command; and
sending the current command to the MTO steering assist unit.

11. The control method set forth in claim 10 , further comprising:
sending the current command and the differential pressure signal to a torque estimation module for generating a next estimation of torque signal.

12. The control method set forth in claim 11 , wherein the left and right wheel speed signals have units of frequency.

13. A control center for a MTO steering system comprising:
a WIR module configured to receive a base torque command, a handwheel angular position signal, an estimation of torque signal, a left wheel speed signal, and a right wheel speed signal to identify a force of disturbance attributable from the left and right wheel speed signals and thereby generate a final torque command used to establish a desired assist torque.

14. The control center set forth in claim 13 , further comprising:
a torque command module configured to receive a differential pressure signal, the estimation of torque signal, a vehicle speed signal, and the handwheel angular position signal to generate a base torque command.

15. The control center set forth in claim 13 , wherein the WIR module includes left and right wheel speed conversion and filter modules configured to respectively receive the left and right wheel speed signals expressed in units of frequency, and generate respective left and right filtered signals expressed in units of frequency, and generate respective left and right radian signals expressed in units of degrees.

16. The control center set forth in claim 15 , wherein the left and right filtered signals are averaged to generate an averaged filtered signal, wherein the WIR module includes a notch filter configured to receive the averaged filtered signal, the base torque command, and the estimation of torque signal to generate a notched torque command, and wherein the notched torque command is reflective of the base torque command subtracted by an adjusted-filtered torque command generated by the averaged filtered signal and the estimation of torque signal.

17. The control center set forth in claim 16 , wherein the notch filter includes a unity gain resonance filter configured to receive the base torque command and apply coefficients reflective of the averaged filtered signal to generate a filtered torque command, and includes a notch filter gain module configured to receive the averaged filtered signal and the estimation of torque signal, compare the signals to data tables and generate a gain value base on the comparison, and wherein the adjusted-filtered torque command is based on the filtered torque command and the gain value.

Assignees

• Steering Solutions Ip Holding

Inventors

• Birsching Joel E
• Champagne Anthony J
• Hales Michael K

Classifications

• B62D7/222 Primary

  acting on the steering wheel · CPC title

• B62D5/0472

  for damping vibrations · CPC title

• B62D5/06

  fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle · CPC title

• B62D5/0835 Primary

  characterised by means for actively influencing the deflection angle of the valve, e.g. depending on driving parameters · CPC title