Electromechanical Brake Force Control via Adaptive Parameter Identification
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Solution Overview
Problem
Existing control systems for electromechanical brake systems face slower response times and reduced performance due to high signal-to-noise ratios when using direct force signals, and inaccuracies associated with parameter variations from temperature fluctuations, friction, and wear when using actuator displacement to determine force.
Innovation Solution
A method that models force as a function of parameters like linear and nonlinear stiffness coefficients, motor damping, and torque constants, allowing for adaptive identification and updating of these parameters based on motor position, velocity, and current signals to accurately determine and control the observed force exerted by the actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct force signals are used to control the electromechanical brake system, then the braking force can be directly monitored, but the response time becomes slower and performance is reduced due to filtering requirements for high signal-to-noise ratio
Solution Approach 1:
The patent introduces an intermediary approach by using actuator displacement as a mediator to infer braking force through a spring model, rather than directly measuring force. This displacement-based indirect measurement avoids the high noise levels and filtering requirements of direct force sensors, thereby improving response time while maintaining sufficient measurement accuracy for control purposes.
Solution Approach 2:
The patent replaces the mechanical direct force measurement system with a computational model that calculates force from displacement measurements. By substituting physical force sensors with a mathematical spring model F = kx, the system eliminates the need for direct force signal processing and filtering, significantly improving response time and performance.
2Speed
If actuator displacement is used to determine force by modeling the brake system as a spring, then the response time improves, but inaccuracies occur due to parameter variations from temperature fluctuations, friction effects, and wear
Solution Approach 1:
The patent applies dynamics by making the spring constant k a variable parameter that adapts to changing operating conditions rather than a fixed value. The system continuously updates the stiffness coefficient based on observed behavior, allowing the model to compensate for temperature fluctuations, friction effects, and wear, thereby maintaining measurement precision while preserving the fast response time benefits.
Solution Approach 2:
The patent changes the parameter representation from a fixed spring constant to a dynamically adjustable stiffness coefficient. By allowing the parameter k to vary and be重新identified based on observed force-displacement relationships, the system compensates for parameter variations caused by temperature, friction, and wear, maintaining accuracy without sacrificing the rapid response characteristics.
3Device complexity
If the brake system parameters are kept fixed, then the control system is simpler, but the accuracy deteriorates due to parameter variations from temperature, friction, and wear
Solution Approach 1:
The patent applies preliminary action by performing parameter identification and updating the stiffness coefficient before critical inaccuracies develop. The system periodically or continuously reidentifies parameters based on observed behavior, proactively compensating for temperature changes, friction effects, and wear before they significantly degrade performance, thus maintaining accuracy without requiring overly complex real-time adjustment mechanisms.
Data Source
AI summary
A method for controlling a force exerted by an actuator on a load, the actuator being driven by a motor, the method including the steps of modeling the force as a function of at least one parameter, the parameter having an initial value, determining a new value for the parameter, determining an observed force based at least in part upon the new value for the parameter and controlling a positioned of the actuator based at least in part upon the observed force.