Magnetic torque overlay steering system with off-road damping

Patent metadata

Field	Value
Publication number	US-10414433-B2
Application number	US-201615215805-A
Country	US
Kind code	B2
Filing date	Jul 21, 2016
Priority date	Jul 22, 2015
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

Technical solutions are described for generating a damping torque in a magnetic torque overlay (MTO) steering system. An example method includes generating a damping torque based on a vehicle speed value, a handwheel velocity value, and a differential pressure value. The method further includes detecting an off-road condition, and in response, computing an off-road damping torque signal based on one or more of the vehicle speed value, the handwheel velocity value, the differential pressure value, and a handwheel angle value. The method also includes scaling the damping torque by the off-road damping torque signal in response to detecting the off-road condition.

First claim

What is claimed is:

1. A steering system comprising:
an off-road damping module configured to:
determine that the steering system is being back-driven and in response:
increment a step value; and
in response to the step value crossing a predetermined maximum-value, set an activation value; and
compute an off-road damping signal, the activation value indicative of whether to use the off-road damping signal to compute a damping torque value; and

a torque generation module configured to:
receive the off-road damping signal computed by the off-road damping module; and
compute a damping torque value based on the off-road damping signal and differential pressure signal value in the steering system.

2. The steering system of claim 1 , wherein the torque generation module computes the damping torque as a product of the off-road damping signal, and a damping blend signal that is based on the differential pressure signal value.

3. The steering system of claim 2 , wherein the damping blend signal is based on a differential pressure value across the steering system.

4. The steering system of claim 1 , wherein the off-road damping module computes the off-road damping signal in response to a vehicle speed being below a predetermined value.

5. The steering system of claim 1 , wherein the off-road damping signal is computed based on a handwheel angle signal, a handwheel velocity signal, a vehicle speed signal, and a differential pressure signal.

6. The steering system of claim 1 , wherein the off-road damping module is configured to activate computing the off-road damping signal in response to a steering wheel of the steering system moving away from a center position.

7. The steering system of claim 6 , wherein the off-road damping module determines that the steering wheel is moving away from the center position based on a sign of a value of a handwheel velocity signal and a sign of a value of a handwheel angle signal.

8. The steering system of claim 1 , wherein the off-road damping module is configured to deactivate computing the off-road damping signal in response to a steering wheel of the steering system moving towards a center position.

9. The steering system of claim 1 , wherein the off-road damping module determines that the system is being back-driven in response to a handwheel speed signal value and a handwheel angle signal value being of the same sign, and the differential pressure signal value being a different sign.

10. The steering system of claim 1 , wherein the off-road damping module is further configured to determine that the steering system is not being back-driven and in response:
decrement the step value; and
in response to the step value being below a predetermined minimum-value, deactivate using the off-road damping signal by resetting the activation value.

11. The steering system of claim 1 , wherein the steering system is a magnetic torque overlay (MTO) based steering system.

Assignees

• Steering Solutions Ip Holding

Inventors

• Birsching Joel E

Classifications

• B62D6/008 Primary

  Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications · CPC title

• B62D5/06 Primary

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

• B60W10/20

  including control of steering systems · CPC title