Magnetic torque overlay steering system with off-road damping
View Patent ↗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.
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.