Electromechanical Actuator Control for Brake Systems
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Solution Overview
Problem
Existing brake-by-wire systems lack precision in setting predetermined setpoint values and curves for electromechanical actuators, leading to suboptimal control behavior.
Innovation Solution
A method that determines a first actuator speed setpoint using the setpoint and actual value, and a second actuator speed setpoint based on a predetermined relationship between the controlled variable and the actuator position, to calculate a manipulated variable for the electromechanical actuator, enhancing speed pre-control and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single actuator speed setpoint is determined using only the setpoint and actual value, then the control structure remains simple, but the setting precision and response accuracy of the actuator are insufficient
Solution Approach 1:
The actuator speed setpoint is segmented into two distinct components: a first actuator speed setpoint determined from the setpoint and actual value, and a second actuator speed setpoint determined from the predetermined relationship between controlled variable and actuator position. This segmentation allows each component to contribute differently to the overall control, improving precision while maintaining manageable complexity through structured decomposition.
Solution Approach 2:
A predetermined relationship between the controlled variable and actuator position is established in advance. This preliminary action enables the system to quickly determine the second actuator speed setpoint based on pre-characterized system behavior, improving response accuracy without requiring complex real-time calculations during operation.
2Speed
If the actuator responds quickly to pressure changes, then the response speed is improved, but the control precision and accuracy deteriorate due to overshooting and oscillations
Solution Approach 1:
The control system continuously monitors the actual value of the controlled variable and uses this feedback to adjust both the first actuator speed setpoint (from the regulator) and the second actuator speed setpoint (from the predetermined relationship). This dual feedback mechanism enables the system to maintain high response speed while correcting for overshooting and oscillations in real-time, thereby preserving control accuracy.
3Productivity
If a linear function is used to calculate model actual pressure value for overcoming air gaps, then large air gaps can be quickly overcome, but the general accuracy of control behavior is not improved
Solution Approach 1:
The system applies different control strategies for different operating conditions: a linear function is used specifically for overcoming large air gaps to maximize speed, while the predetermined relationship between controlled variable and actuator position is used for general operation to maintain high accuracy. This localized application of different models ensures optimal performance in each specific scenario without compromising overall control quality.
Data Source
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AI summary
The invention relates to a method for controlling an electromechanical actuator (1, 2) of a brake system for motor vehicles, according to which method an actual value, in particular a measured actual value, of a controlled variable (PSys,Ist, FIst) is intended to be set to a specified target value (PSys,Soll, FSoll), wherein a first actuator speed target value (ωAkt,Soll,DR,Ctrl) is determined on the basis of the target value (PSys,Soll, FSoll) and the actual value (PSys,Ist, FIst), in particular by means of a first controller (19, 20), and wherein a manipulated variable (ωAkt,Soll, MAkt,Soll) for the electromechanical actuator (1, 2) is determined on the basis of the first actuator speed target value and a second actuator speed target value (ωAkt,Soll,DR,FFW, 1), wherein the second actuator speed target value (ωAkt,Soll,DR,FFW, 1) is determined on the basis of the target value and a specified relationship (30, 40) between the controlled variable (PSys, F) and a variable (XAkt) corresponding to a position of the electromechanical actuator. The invention further relates to a control device for an electromechanical actuator (1, 2) of a brake system for motor vehicles.