Method for operating an control device for a braking system of a motor vehicle, control device and motor vehicle
The invention relates to a method for operating a control device for a braking system of a motor vehicle, wherein the control device receives a braking request from a driver assistance system and determines a target value of a braking operation parameter of the braking system and determines an ideal temporal process for the braking operation parameter, which gradually leads to the target value, complying with a predetermined jerk criterion, and a determines a control fault of an actual value of the braking operation parameter in relation to the ideal process and determines a request value for a controller of a brake pressure pump of the braking system from the control fault on the basis of a controller unit. According to the invention, the control device determines a maximum achievable temporal gradient of the braking operation parameter by means of the brake pressure pump and examines whether the gradient fulfills a freezing criterion and, in the case of the freezing criterion being fulfilled, limits at least one control operation parameter of the controller unit and/or a gradient of the brake request.
1. A method for operating a control device for a braking system of a motor vehicle, wherein the control device is configured to:
receive a braking request from a driver assistance system;
determine a target value of a braking operation parameter of the braking system for said braking request;
determine an ideal temporal course for said braking operation parameter, which ideal temporal course gradually leads to the target value corresponding to a predetermined jerk condition;
determine a control error of an actual value of the braking operation parameter in relation to the ideal temporal course and determine a request value for a closed-loop controller of a brake pressure pump of the braking system from said control error on the basis of a closed-loop controller unit; and to
set the request value in the closed-loop controller; wherein
the control device is configured to determine a maximum achievable temporal gradient of the braking operation parameter using the brake pressure pump and to check whether the maximum achievable temporal gradient fulfills a predetermined freezing criterion, and, when the freezing criterion is fulfilled, to limit at least one control operation parameter of the closed-loop controller unit and/or a gradient of the braking request to a respectively prescribed maximum value, so that the control device configures the closed-loop controller unit depending on the current capacity of the brake pressure pump with regard to the maximum achievable temporal gradient of the braking operation parameter at the current operating point.
2. The method according to claim 1 , wherein the closed-loop controller unit comprises a closed-loop controller having an I component (integral component) and the I component is limited as the at least one control operation parameter.
3. The method according to claim 1 , wherein, when the freezing criterion is not fulfilled, the at least one control operation parameter, as a function of the control error, is allowed to become larger than the respectively prescribed maximum value.
4. The method according to claim 1 , wherein the freezing criterion requires the maximum achievable temporal gradient to be smaller than a gradient of the ideal temporal course.
5. The method according to claim 1 , wherein, after it has been identified that the freezing criterion has been fulfilled, the at least one control operation parameter is limited after a predetermined waiting time.
6. The method according to claim 1 , wherein the braking operation parameter is a braking moment or a braking pressure or a braking force.
7. The method according to claim 1 , wherein an elapsed length of time starting at the reception of the braking request is determined and for at least one current point in time, a current value of the maximum achievable temporal gradient determined depending on a value of the elapsed length of time and on a basis of a model of the braking system.
8. The method according to claim 7 , wherein the model approximates a functional relationship between a conveyed brake fluid volume and a resulting braking pressure using a second order polynomial.
9. The method according to claim 1 , wherein the predetermined jerk criterion requires a jerk produced in the motor vehicle to be smaller than a predetermined maximum value when the braking request is set.
10. The method according to claim 1 , wherein the jerk criterion requires a jerk produced in the motor vehicle to be constant.
11. The method according to claim 1 , wherein the braking request is received from one or more of an adaptive cruise control system, a parking assistance system, a braking speed-control system, and a braking speed-limiter.
12. A control device for a braking system of a motor vehicle, wherein the control device comprises a processor that is configured to:
receive a braking request from a driver assistance system;
determine a target value of a braking operation parameter of the braking system for said braking request;
determine an ideal temporal course for said braking operation parameter, which ideal temporal course gradually leads to the target value corresponding to a predetermined jerk condition;
determine a control error of an actual value of the braking operation parameter in relation to the ideal temporal course and determine a request value for a closed-loop controller of a brake pressure pump of the braking system from said control error on the basis of a closed-loop controller unit; and to
set the request value in the closed-loop controller; wherein
the control device is configured to determine a maximum achievable temporal gradient of the braking operation parameter using the brake pressure pump and to check whether the maximum achievable temporal gradient fulfills a predetermined freezing criterion, and, when the freezing criterion is fulfilled, to limit at least one control operation parameter of the closed-loop controller unit and/or a gradient of the braking request to a respectively prescribed maximum value, so that the control device configures the closed-loop controller unit depending on the current capacity of the brake pressure pump with regard to the maximum achievable temporal gradient of the braking operation parameter at the current operating point.
13. A motor vehicle comprising a driver assistance system and a braking system, wherein the driver assistance system and the braking system are coupled to one another via a control device that is configured to:
receive a braking request from a driver assistance system;
determine a target value of a braking operation parameter of the braking system for said braking request;
determine an ideal temporal course for said braking operation parameter, which ideal temporal course gradually leads to the target value corresponding to a predetermined jerk condition;
determine a control error of an actual value of the braking operation parameter in relation to the ideal temporal course and determine a request value for a closed-loop controller of a brake pressure pump of the braking system from said control error on the basis of a closed-loop controller unit; and to
set the request value in the closed-loop controller; wherein
the control device is configured to determine a maximum achievable temporal gradient of the braking operation parameter using the brake pressure pump and to check whether the maximum achievable temporal gradient fulfills a predetermined freezing criterion, and, when the freezing criterion is fulfilled, to limit at least one control operation parameter of the closed-loop controller unit and/or a gradient of the braking request to a respectively prescribed maximum value, so that the control device configures the closed-loop controller unit depending on the current capacity of the brake pressure pump with regard to the maximum achievable temporal gradient of the braking operation parameter at the current operating point.