Technical solutions are described for mitigating traction steer using an electric power steering system (EPS). A control system for a power steering system including a processor and memory are provided. The memory includes instructions that, when executed by the processor, cause the processor to generate a motor command as a function of a handwheel velocity, and to modify the motor command based upon a traction torque signal. A method for controlling a power steering system is also provided. The method includes generating a motor command as a function of a handwheel velocity; modifying the motor command based upon a traction torque signal; and applying the motor command to an actuator of the power steering system.

Technical solutions are described for mitigating traction steer using an electric power steering system (EPS). A control system for a power steering system including a processor and memory are provided. The memory includes instructions that, when executed by the processor, cause the processor to generate a motor command as a function of a handwheel velocity, and to modify the motor command based upon a traction torque signal. A method for controlling a power steering system is also provided. The method includes generating a motor command as a function of a handwheel velocity; modifying the motor command based upon a traction torque signal; and applying the motor command to an actuator of the power steering system.

A method and system for estimating surface roughness of a ground for an off-road vehicle to control ground speed comprises detecting motion data of an off-road vehicle traversing a field or work site during a sampling interval. A pitch sensor is adapted to detect pitch data of the off-road vehicle for the sampling interval to obtain a pitch acceleration. A roll sensor is adapted to detect roll data of the off-road vehicle for the sampling interval to obtain a roll acceleration. An electronic data processor or surface roughness index module determines or estimates a surface roughness index based on the detected motion data, pitch data and roll data for the sampling interval. The surface roughness index can be displayed on the graphical display to a user or operator of the vehicle, or applied to control or execute a ground speed setting of the vehicle.

A method and system for estimating surface roughness of a ground for an off-road vehicle to control ground speed comprises detecting motion data of an off-road vehicle traversing a field or work site during a sampling interval. A pitch sensor is adapted to detect pitch data of the off-road vehicle for the sampling interval to obtain a pitch acceleration. A roll sensor is adapted to detect roll data of the off-road vehicle for the sampling interval to obtain a roll acceleration. An electronic data processor or surface roughness index module determines or estimates a surface roughness index based on the detected motion data, pitch data and roll data for the sampling interval. The surface roughness index can be displayed on the graphical display to a user or operator of the vehicle, or applied to control or execute a ground speed setting of the vehicle.

[Problem] An object of the present invention is to provide an electric power steering apparatus capable of smoothly switching the control systems without self-steer by gradually changing a control torque of the torque control and a command value of the position/speed control upon fade processing that switches the control systems.

[Means for Solving the Problem] The present invention is the electric power steering apparatus including a torque sensor to detect a steering torque and a motor control unit to control a motor that applies an assist torque to a steering system of a vehicle, comprising: a function to switch a control system of the motor between a torque control system of a torque system to control a motor output torque and a position/speed control system of a steering angle system to control a steering angle of a steering in accordance with a predetermined switching trigger, wherein each of a steering angle command value and a steering angle speed of the position/speed control system and an assist torque level of the torque control system gradually change sensitive to the steering torque, when shifting from the torque control system to the position/speed control system or vice versa.

[Problem] An object of the present invention is to provide an electric power steering apparatus capable of smoothly switching the control systems without self-steer by gradually changing a control torque of the torque control and a command value of the position/speed control upon fade processing that switches the control systems.

[Means for Solving the Problem] The present invention is the electric power steering apparatus including a torque sensor to detect a steering torque and a motor control unit to control a motor that applies an assist torque to a steering system of a vehicle, comprising: a function to switch a control system of the motor between a torque control system of a torque system to control a motor output torque and a position/speed control system of a steering angle system to control a steering angle of a steering in accordance with a predetermined switching trigger, wherein each of a steering angle command value and a steering angle speed of the position/speed control system and an assist torque level of the torque control system gradually change sensitive to the steering torque, when shifting from the torque control system to the position/speed control system or vice versa.

A steering assist system for a vehicle comprises a steering assist module configured to determine a baseline assistance force to be applied to a steering system of the vehicle, and a transient disturbance compensation module configured to determine a transient compensation force to compensate for transient conditions that urge the vehicle to deviate from a straight path. The transient compensation force is based at least partially on the determined baseline assistance force. The system also includes a steady-state disturbance compensation module configured to determine a steady-state compensation force to compensate for steady-state conditions that urge the vehicle to deviate from the straight path, the steady-state compensation force being based at least partially on the determined baseline assistance force. Methods relate to controlling steering systems.

Technical features of a steering system include a control module that dynamically determines an operating mode based on a set of input signal values such as lateral acceleration signal values and corresponding handwheel position values. The control module dynamically determines and learns classification boundaries between multiple operating modes based the input signal values. The control module further calibrates the steering system according to operating mode that is determined using the classification boundaries.

Technical features of a steering system include a control module that dynamically determines an operating mode based on a set of input signal values such as lateral acceleration signal values and corresponding handwheel position values. The control module dynamically determines and learns classification boundaries between multiple operating modes based the input signal values. The control module further calibrates the steering system according to operating mode that is determined using the classification boundaries.

Restriction values (upper limit and lower limit) for an assist control amount are set individually for each of state amounts including steering torque τ used to compute the assist control amount. A value obtained by summing such restriction values is set as a final restriction value for the assist control amount. Even though the assist control amount with an abnormal value is computed, the assist control amount is restricted to an appropriate value by the final restriction value. In addition, a transition is made from a primary assist control amount which is restricted to a secondary assist control amount computed separately from the primary assist control amount at the timing when a certain time elapses since the assist control amount is restricted. As the steering torque τ is increased, the speed of transition from the primary assist control amount to the secondary assist control amount is increased.