Method for operating a power steering mechanism

• US 9,555,829 B2
• Filed: 05/09/2013
• Issued: 01/31/2017
• Est. Priority Date: 11/15/2010
• Status: Active Grant

• Current Assignee: Robert Bosch Automotive Steering GmbH (Robert Bosch GmbH)
• Original Assignee: Robert Bosch Automotive Steering GmbH (Robert Bosch GmbH)
• Inventors: Sprinzl, Michael
• Primary Examiner(s): Nguyen, Nga X
• Assistant Examiner(s): WALLACE, DONALD JOSEPH
• Application Number:
  US13/890,641
• Publication Number:
  US 20130245893A1
• Time in Patent Office: 1,363 Days
• Field of Search: 701/41, 701/42, 701/43, 701/44
• US Class Current: 1/1
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: B62D 5/0481 monitoring the steering system, e.g. failures
• CPC Class Codes: B62D 5/0493 detecting processor errors, e.g. plausibility of steering direction
• CPC Class Codes: B62D 6/008 Control of feed-back to the steering input member, e.g. simulating road feel in steer-by-wire applications

Abstract

Provided is a method for operating a power steering system and to such a power steering system. A motor torque is computed by an electronic processor and is established by suitable motor actuation, wherein a plausibility check of the computed motor torque is carried out, taking a measured manual torque into consideration. A value of the additional torques of at least one special function is further considered in the plausibility check.

Claims

1. A method for operating a power steering system comprising an electronic processor for computing a motor torque, an electric motor for introducing the motor torque, and a device for detecting a measured manual torque, the method comprising:

computing the motor torque by the electronic processor as a function of the measured manual torque;

correcting said measured manual torque by either one of adding or subtracting a value of added torques of at least one special function to said measured manual torque to achieve a corrected manual torque that equals the measured manual torque plus or minus said value of added torques of said at least one special function;

substituting the corrected manual torque for the measured manual torque as an input to a plausibility check of the computed motor torque;

performing said plausibility check of the computed motor torque by the electronic processor based on said corrected manual torque; and

introducing the computed motor torque by the electric motor in dependence of a result of performing the plausibility check.

2. A method according to claim 1, wherein the measured manual torque, which is detected by way of a manual torque sensor, is controlled by specifying a target manual torque.

3. A method according to claim 1, which is carried out based on the following requirements:

the added torques must only be requested in appropriate special situations and must be monitored and limited in terms of time; and

the added torques must be subject to a plausibility check of application direction for said added torques and exclude undesirable, potentially oscillating changes in signs.

4. A control unit comprising an electronic processor and a computer program code means that configures the electronic processor to perform the following:

compute a motor torque as a function of the measured manual torque;

correct said measured manual torque by either one of adding or subtracting a value of added torques of at least one special function to said measured manual torque to achieve a corrected manual torque that equals the measured manual torque plus or minus said value of added torques of said at least one special function;

substitute the corrected manual torque for the measured manual torque as an input to a plausibility check of the computed motor torque;

perform said plausibility check of the computed motor torque by the electronic processor based on said corrected manual torque;

introduce the computed motor torque by the electric motor in dependence of a result of performing the plausibility check.

5. A control unit comprising said electronic processor and a computer-readable data medium that configures the electronic processor to perform the following:

compute a motor torque as a function of a measured manual torque;

correct said measured manual torque by either one of adding or subtracting a value of added torques of at least one special function to said measured manual torque to achieve a corrected manual torque that equals the measured manual torque plus or minus said value of added torques of said at least one special function;

substitute the corrected manual torque for the measured manual torque as an input to a plausibility check of the computed motor torque;

perform said plausibility check of the computed motor torque by the electronic processor based on said corrected manual torque; and

introduce the computed motor torque by the electric motor in dependence of a result of performing the plausibility check.

6. A method for operating a power steering system having a parameter-based steering safety function without deactivating the safety function and without modification of parameters of the safety function, the power steering system comprising an electronic processor for computing a motor torque, an electric motor for introducing the motor torque, and a device for detecting a measured manual torque, the method comprising:

computing the motor torque by the electronic processor that is established by suitable motor actuation of the electric motor, said computed motor torque being a function of the measured manual torque;

checking by the electronic processor, prior to said suitable motor actuation, for plausibility of the computed motor torque based on a corrected manual torque; and

introducing the computed motor torque by the electric motor when said checking results in said computed motor torque being plausible so as to achieve a power steering system output torque that is a superposition of the computed motor torque to said measured manual torque; and

introducing the computed motor torque by the electric motor in dependence of a result of performing the plausibility check; and

wherein said corrected manual torque is the measured manual torque plus or minus a value of added torques of at least one special function;

wherein the electronic processor is configured to correct said measured manual torque by either one of adding or subtracting said value of added torques of said at least one special function to achieve said corrected manual torque as said measured torque plus or minus said value of added torques so as to avoid deactivating said parameter-based safety function when introducing said computed motor torque and so as to avoid a need to modify parameters of the parameter-based safety function in order for the parameter-based safety function to pass; and

wherein the electronic processor is configured to check for plausibility of the computed motor torque by substituting the corrected manual torque for the measured manual torque as an input to said parameter-based safety function.