Method for providing steering assistance for an electromechanical steering system of a motor vehicle comprising a redundantly designed control device

Patent metadata

Field	Value
Publication number	US-2021206427-A1
Application number	US-201916967476-A
Country	US
Kind code	A1
Filing date	Feb 7, 2019
Priority date	Feb 12, 2018
Publication date	Jul 8, 2021
Grant date	—

Abstract

Methods for providing steering assistance for an electromechanical steering system having a redundant control unit with a primary and a secondary control path. Respective primary and secondary control paths each have a computing unit, gate driver module, and power module. The method includes detecting an applied steering torque; calculating a primary and secondary motor target torque in the primary computing unit as a function of the applied steering torque; transmitting the primary motor target torque to a primary motor controller of the primary computing unit; determining primary motor currents to operate a primary electric motor or a primary winding group of the electric motor in the primary motor controller; transferring the secondary motor target torque from the primary computing unit to a secondary motor controller and determining secondary motor currents for operation of a secondary electric motor or a secondary winding group of the electric motor.

First claim

1 .- 13 . (canceled)

14 . A method for providing steering assistance for an electromechanical steering system of a motor vehicle having a steering pinion connected to a lower steering shaft, which engages a rack mounted in a housing to be movable along a longitudinal axis for steering wheels, at least two electric motors or one electric motor with at least two winding groups for steering assistance, a torque sensor arranged between an upper steering shaft connected to the steering wheel and the lower steering shaft, and an electronic control unit for calculating the steering assistance, wherein the electronic control unit comprises a redundant control device with a primary control path and a secondary control path, wherein the primary control path has a primary computing unit, a primary gate driver module and a primary power module, and the secondary control path has a secondary computing unit, a secondary gate driver module, and a secondary power module, the method comprising:
detecting an applied steering torque with the torque sensor, when in a fault-free case, calculating a primary motor target torque and a secondary motor target torque in the primary computing unit as a function of at least the applied steering torque, transferring the primary motor target torque to a primary motor controller of the primary computing unit, determining primary motor currents for operating a primary electric motor or a primary winding group of the electric motor in the primary motor controller, transferring the secondary motor target torque from the primary computing unit by means of a signal line to a secondary motor controller of the secondary computing unit, and determining secondary motor currents for the operation of a secondary electric motor or a secondary winding group of the electric motor in the secondary motor controller of the secondary computing unit.

15 . The method of claim 14 , further comprising:
detecting a fault state in one of the control paths, and switching off the steering assistance of the faulty control path.

16 . The method of claim 15 wherein when one of the control paths is in a fault state, the faulty control path stops the communication with the fault-free computing unit over the signal line and the fault-free control path detects the fault state on the basis of the missing communication.

17 . The method of claim 14 , further comprising:
switching off, when the primary control path has a fault, the steering assistance by the primary electric motor or the primary winding of the electric motor, calculating the secondary motor target torque in the secondary computing unit as a function of the applied steering torque, transferring the secondary motor target torque to the secondary motor controller of the secondary computing unit, and determining the secondary motor currents for operating the secondary electric motor or a secondary winding group of the electric motor in the secondary motor controller of the secondary computing unit.

18 . The method of claim 14 wherein the primary computing unit is connected to a primary motor vehicle bus, wherein the secondary computing unit communicates with the motor vehicle via the primary motor vehicle bus by means of the signal line present between the primary and secondary computing units.

19 . The method of claim 14 wherein the primary control path is connected to a primary motor vehicle bus and the secondary control path is connected to a secondary motor vehicle bus which is separated from the primary motor vehicle bus.

20 . The method of claim 14 comprising at least one further input variable selected from vehicle speed, instantaneous rotor position measured by means of a rotor position sensor, or measured current values in the phase windings.

21 . The method of claim 14 wherein the primary control path and the secondary control path each have an integrated circuit connected to the power supply, which takes on the current monitoring of the corresponding computing unit and a rotor position sensor.

22 . The method of claim 14 wherein each of the primary control path and the secondary control path has an external power supply.

23 . The method of claim 14 wherein the secondary computing unit is configured to be less powerful than the primary computing unit.

24 . The method of claim 14 wherein the primary and secondary computing unit is an MCU.

25 . The method of claim 14 wherein the integrated circuits are SBCs.

26 . An electromechanical steering system for a motor vehicle, comprising:
a steering pinion connected to a lower steering shaft, which engages a rack for steering wheels which is mounted in a housing so as to be movable along a longitudinal axis, at least one electric motor configured to generate steering assistance, a torque sensor disposed between an upper steering shaft connected to a steering wheel and the lower steering shaft and which detects a user-applied torque, and an electronic control unit for calculating the steering assistance, which has a redundant control device configured to perform the method of claim 14 .

Assignees

• Thyssenkrupp Presta Ag
• Thyssenkrupp Ag

Inventors

• Balogh Andras
• Horvath Gergely
• Varga Tamas
• Pinter Gergely

Classifications

• B62D5/0403

  characterised by constructional features, e.g. common housing for motor and gear box · CPC title

• B62D5/0484 Primary

  for reaction to failures, e.g. limp home · CPC title

• B62D5/046

  Controlling the motor · CPC title

• B62D5/049

  detecting sensor failures · CPC title

• B62D5/0463

  calculating assisting torque from the motor based on driver input · CPC title