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DE-102024210846-A1 - Method for operating a power steering system

DE102024210846A1DE 102024210846 A1DE102024210846 A1DE 102024210846A1DE-102024210846-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 via a provided requested trajectory, after detection of a fault in the power steering the rack is moved towards a zero position, the movement of the rack towards the zero position 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 (9)

  1. Method for operating a power steering system (500) comprising 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 provided requested trajectory, after detection of a fault in the power steering system (502), the rack (504) is moved towards a zero position (312), the movement of the rack (504) towards the zero position (312) is aborted when the driver regains control of the vehicle (500) and intervention occurs via the steering handle (505).
  2. Procedure according to Claim 1 , in which the requested trajectory is provided by a trajectory controller (202).
  3. Procedure according to Claim 1 or 2 , in which a warning signal is first given to the driver after the fault is detected.
  4. Procedure according to Claim 3 , in which a visual and/or acoustic warning signal is emitted.
  5. Procedure according to one of the Claims 1 until 4 , in which the movement of the rack (504) towards the zero position (312) takes place after a debounce period (324).
  6. Procedure according to one of the Claims 1 until 5 , in which the movement of the rack (505) towards the zero position (312) is such that it is completed by the end of a waiting period (331).
  7. Procedure according to one of the Claims 1 until 6 , in which the movement of the rack (504) towards the zero position (312) is continuous.
  8. Procedure according to Claim 7 , in which the movement of the rack (505) towards the zero position (312) follows a ramp (329).
  9. Arrangement for operating a power steering system (502) comprising 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 arrangement (506) comprises an evaluation unit (508) which is used to carry out a method according to one of the Claims 1 until 8 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 wheel handles. During such driving operations, it must be ensured that safe continued driving is guaranteed even in the event of a system malfunction. In the event of a power steering malfunction, it is necessary to inform the driver of this malfunction and, if necessary, to put the vehicle into a condition in which there is no danger to other road users and the driver is not impaired. One way to do this, for example to correct the error of communication failure with the higher-level control unit ( 1 To intercept errors (reference number 16), the measure KLA (Keep Last Angle: Maintaining the Last Position) is used. As a first step, the driver is informed of the error. This is done, for example, with an acoustic and/or visual signal. This mechanism is also used in the event of a main microcontroller failure, e.g., due to the critical task overflow error. In this case, the system switches to the backup microcontroller, which itself does not have bus communication. In a second step, the last position or angle (KLA) on the rack is maintained until the driver regains control of the vehicle. If this takeover does not occur within a predetermined time period, e.g., within 2 seconds, manual steering can be activated and further measures can be taken. This procedure is necessary to prevent a sudden return of the steering to straight-ahead driving, especially when cornering. Disclosure of the invention Against this background, a method with the features of claim 1 and an arrangement according to claim 9 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. This handle is used to influence the direction of travel of a vehicle in which the power steering system is located and 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 predetermined by a requested trajectory, typically provided by a trajectory controller. That is, in this case, the driver's hands are not on the steering handle or the steering wheel; the driver does not intervene via the steering handle and therefore does not influence the direction of travel. This is also referred to as SAE Level 2+, where the power steering system takes over tasks previously performed by the driver. After a power steering fault is detected, the rack is now moved towards the zero position in a controlled manner with a specific, adjustable gradient. A fault signifies a condition in which the power steering no longer operates reliably. The zero position of the rack is the position in which the vehicle travels straight ahead. This procedure specifically addresses the fault response KLA (Communication and Alert System). This response is activated as described above, i.e., in the event of a fault, communication failure, or a switch to the backup microcontroller. a serious fault on the main microcontroller. The movement of the rack towards the zero position is aborted when the driver regains control of the vehicle and intervenes via the steering handles. This means that the driver's hands are once again on the steering handles. Before the rack is moved, a warning signal is typically given to the driver. This occurs as soon as possible after the fault occurs. If the driver reacts immediately to this warning signal, which can be recognized by the fact that they put their hands back on the steering handles and actively steer, then it may not be necessary to initiate the movement of the rack