Methods, systems and apparatus for steering wheel vibration reduction in electric power steering systems

A vehicle comprising:

• a steering wheel coupled to one or more tires to steer the one or more tires;
• and
• an electric motor coupled to the one or more tires to generate a motor torque that assists the steering of the one or more tires;
• and
• a control module coupled to the electric motor and configured to:
• determine a gross torque attributable to periodic disturbances in the vehicle;
• identify a desired amount of suppression for the periodic disturbances at the steering wheel;
• determine an offset torque based on the gross torque and the desired amount of suppression;
• and
• generate a motor command signal in a manner that is influenced by the offset torque, wherein the motor command signal is applied to the electric motor to control the motor torque and attenuate the periodic disturbances communicated to the steering wheel.

A method for reducing vibrations at a steering wheel caused by periodic disturbances in a steering system corresponding to one or more tires of a vehicle, the steering system including the steering wheel and an electric motor coupled to the steering wheel and the one or more tires to apply a motor torque that assists the steering of the one or more tires by the steering wheel, the method comprising:

• determining quadrature and coincident components of a measured disturbance torque at an angular frequency corresponding to the one or more tires;
• determining a cancellation component of the motor torque;
• determining a gross torque attributable to the periodic disturbances in the steering system based on the cancellation component and the quadrature and coincident components of the measured disturbance torque at the angular frequency;
• identifying a gain factor corresponding to a desired amount of suppression of the vibrations;
• multiplying the gross torque by the gain factor to obtain an offset torque;
• transforming the offset torque to quadrature and coincident offset torque components;
• generating a quadrature extracted envelope component based on a first difference between the quadrature component of the measured disturbance torque at the angular frequency and the quadrature offset torque component, the quadrature extracted envelope component corresponding to an amplitude envelope of the first difference;
• generating a coincident extracted envelope component based on a second difference between the coincident component of the measured disturbance torque at the angular frequency and the coincident offset torque component, the coincident extracted envelope component corresponding to an amplitude envelope of the second difference;
• and
• generating a motor command signal based at least in part on the quadrature and coincident extracted envelope components, wherein the motor command signal influences the motor torque to attenuate the vibrations transmitted to the steering wheel by the desired amount.