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DE-102024210828-A1 - Method for operating a power steering system

DE102024210828A1DE 102024210828 A1DE102024210828 A1DE 102024210828A1DE-102024210828-A1

Abstract

Method for operating a power steering system comprising a steering handle by which the direction of travel of a vehicle can be influenced and which acts on a rack whose position determines the direction of travel, wherein the vehicle is in a state in which the direction of travel is specified by a requested trajectory calculated by the power steering system, after detection of a fault in the power steering system the control of the rack is carried out via a substitute position controller, the control via the substitute position controller is aborted when the driver regains control of the vehicle and intervention via the steering handle takes place.

Inventors

  • Thomas Wanner
  • Jishnu Radhakrishnan
  • Akshay Cariappa Panathale Nandakumar

Assignees

  • Robert Bosch Gesellschaft mit beschränkter Haftung

Dates

Publication Date
20260513
Application Date
20241112

Claims (8)

  1. Method for operating a power steering system (500) which has a steering handle (505) by which the direction of travel of a vehicle (500) can be influenced and which acts on a rack (504) whose position determines the direction of travel, wherein: the vehicle (500) is in a state in which the direction of travel is specified by a requested trajectory calculated by the power steering system (502), >after detection of a fault in the power steering system (502), the rack (504) is controlled via a substitute position controller (260, 507), >the control via the substitute position controller (260, 507) is aborted when the driver regains control of the vehicle (500) and intervention via the steering handle (505) takes place.
  2. Procedure according to Claim 1 , in which a warning signal is first given to the driver after the fault is detected.
  3. Procedure according to Claim 2 , in which a visual and/or acoustic warning signal is emitted.
  4. Procedure according to one of the Claims 1 until 3 , in which the substitute position controller (260, 507) controls the rack (504) in such a way that the direction of travel corresponds to the requested trajectory.
  5. Procedure according to Claim 4 , which checks whether the requested trajectory leads to an invalid rack position.
  6. Procedure according to Claim 6 , in which, if an invalid rack position is detected, the last valid rack position is maintained.
  7. Procedure according to one of the Claims 1 until 6 , which is performed during a ride at SAE Level 2+.
  8. Arrangement for operating a power steering system with a unit designed to carry out a procedure rens after one of the Claims 1 until 7 is set up.

Description

The invention relates to a method for operating a power steering system and an arrangement for carrying out the method. State of the art Power steering, also known as assisted steering, reduces the force required to operate steering controls, particularly the steering wheel. This is helpful, for example, when steering while stationary, maneuvering, and at low speeds. Typically, an additional torque is provided by a motor, which compensates for the steering effort applied by the driver. In such a power steering system, for example, a rack and pinion drive is used, in which a rack is moved by a pinion turned by the steering handle and then usually moves a tie rod. The movement of this rack, especially its speed, is monitored to ensure the safe operation of the entire power steering system. Different levels of automation can be implemented in vehicle operation, depending on the extent to which the driver is supported in using the vehicle. SAE levels (SAE: Society of Automotive Engineers) are defined to precisely classify the degree of automation, using a scale of six levels. Level 0 corresponds to driving without any automation, while Level 5 represents full automation. These levels thus classify assisted, automated, and autonomous driving (Level 5). This section discusses SAE Level 2 and SAE Level 2+ in more detail, where the driver is permitted to remove their hands from the steering handlebars or steering wheel. During such driving operations, it must be ensured that safe continued driving is guaranteed even in the event of a system malfunction. Disclosure of the invention Against this background, a method with the features of claim 1 and an arrangement according to claim 8 are presented. Embodiments are described in the dependent claims and in the description. The presented method is used to operate a power steering system that includes a steering handle for influencing the vehicle's direction of travel. This handle acts on a rack whose position determines the direction of travel. In this method, the vehicle is in a state where the direction of travel is specified by a requested trajectory calculated by the power steering system. This corresponds, for example, to SAE Level 2+. After a fault is detected in the power steering system, the rack is controlled via a backup position controller. A fault is a condition in which the power steering can no longer be operated safely or even fails completely. The backup position controller is a quality management (QM) consumer, i.e., a consumer without a safety classification. The control via the substitute position controller is aborted when the driver regains control of the vehicle and an intervention is made via the steering handle. The presented procedure provides for replacing the "Damping Mitigation Measure" with the "Switching to a backup position controller" measure in the event of a power steering failure. This is a quality management (QM) consumer without a safety classification or safeguards. Therefore, it is only used for a limited period, e.g., 2.5 seconds. The presented arrangement serves to carry out the procedure and includes an evaluation unit configured for this purpose. The arrangement and/or the evaluation unit is/are implemented in hardware and/or software. The arrangement can be integrated into a vehicle control unit or be designed as such a control unit. The presented method ensures that the requested trajectory is followed at least for a limited period of time, unlike other methods which dampen the rack movement, preventing jerky movement but allowing the movement itself. Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention. Brief description of the drawings 1 A block diagram shows a vehicle at the vehicle level.2 A block diagram shows a steering control unit.3 A block diagram shows an embodiment of the presented safety mechanism.4 A flowchart shows a possible, highly simplified representation of the presented procedure.5 The figure shows, in a schematic, highly simplified representation, a vehicle with one embodiment of the described arrangement. Embodiments of the invention The invention is schematically illustrated with reference to embodiments in the drawings and is described in detail below with reference to the drawings. 1 The block diagram shows the basic structure of a vehicle at the vehicle level. The diagram depicts sensors 12, a vehicle state 14, an SAE L2+ vehicle control system 16, a driver monitoring system 18, a human-machine interface (HMI) 20, a driver 22, a powertrain control system 24, a powertrain 26, a brake system 28, a steering control system 30, and a steering system 32. 1 This particularly highlights the specific problem