Device for determining the absolute angular position of the steering wheel of an electric power-assisted steering column of a motor vehicle using weighted dynamic parameters of the vehicle

A method for determining the absolute angular position of a steering wheel of an electric power-assisted steering column of a motor vehicle, comprising at least one means for measuring a dynamic parameter while the vehicle is running, the power-assisted steering column of the motor vehicle comprising:

• an electric assistance motor steered by an electronic computer and comprising a rotor performing a number of turns (Nturns—elec) during the rotation of the steering wheel,
• a reduction gear at the output of the gear reduction (Γ) electric motor,
• an angular position sensor of the rotor of the motor, of the“resolver” type and measuring a single-turn absolute position (θmono-elec) depending on a number of pairs of poles (n) distributed between the angular sensor and the rotor of the motor, and
• a torque sensor making it possible to determine the torque exerted on the steering wheel by the driver,
• the method being characterized in that it comprises the following steps:
• initializing, at 0, the number of turns (Nturns—elec) of the rotor of the electric motor when the vehicle is started,
• periodically determining a multi-turn relative angular position of the steering wheel, in particular using the formula:
• θ
• relative
• ⁢
• ⁢
• steering
• ⁢
• ⁢
• wheel
• =
• θ
• mono
• ⁢
• ⁢
• elec
• ×
• N
• turns
• ⁢
• -
• ⁢
• elec
• Γ
• ×
• n
• determining at least one dynamic parameter relating to the running conditions of the vehicle using the at least one means for measuring that parameter,
• determining internal data of the electric power-assisted steering column comprising the engine speed and the steering lock torque, which is equal to the sum of the steering torque of the motor and the torque exerted by the driver,
• determining an absolute steering wheel angle calculated according to the at least one dynamic parameter on the dynamic running conditions of the vehicle,
• checking the validity of the calculated value of the absolute steering wheel angle as a function of the dynamic running conditions of the vehicle in which it has been determined as well as internal data of the electric power-assisted steering column,
• weighting the calculated value of the absolute steering wheel angle according to a test of the validity of the calculated value of the absolute steering wheel angle, and the origin of said value, i.e. the measurement means used to determine said at least one dynamic parameter,
• determining a recalibration authorization value for the absolute position of the steering wheel, and
• recalibrating the position of the steering wheel on the recalibration authorization value.