Method for controlling an assistance motor of a power steering system comprising an algorithm for compensating the oscillations of a steering wheel linked to the presence of an imbalance

A method for controlling an assistance motor of a power steering system, said power steering system comprising at least one steering wheel configured to receive a steering wheel torque applied by a driver, the assistance motor configured to apply a motor torque to a rack, at least one wheel connected to said rack, and at least one steering computer, the method comprising:

• executing, by the at least one steering computer, a main control algorithm, the main control algorithm comprising a step of determining a main motor torque as a function of at least the steering wheel torque;
• and
• executing, by the at least one steering computer, a compensation algorithm that compensates for an oscillation of the steering wheel induced by an imbalance present on at least one of the at least one wheel, the compensation algorithm comprising a step of determining a compensation motor torque such that the steering wheel torque becomes equal to a reference steering wheel torque, the reference steering wheel torque having a fixed value,
• wherein the step of determining the compensation motor torque comprises a phase of calculating a steering wheel torque error by determining a difference between the steering wheel torque and the reference steering wheel torque and a phase of filtering low frequencies by a high-pass filter, the high-pass filter having a cut-off frequency chosen to compensate said oscillation induced by said imbalance,
• wherein an operating frequency of the compensation algorithm is selectable independently of an operating frequency of the main control algorithm,
• wherein an amplitude of the oscillation of the steering wheel is directly related to a magnitude of the imbalance, the amplitude being measurable using the steering wheel torque, and
• wherein a frequency of the steering wheel oscillation is proportional to a vehicle speed,
• wherein the steering wheel applies torque to the rack at a first location of the rack, and the assistance motor applies the motor torque to the rack at a second location of the rack that is different from the first location.