Electro-Mechanical Brake Control Using Velocity Observer
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Solution Overview
Problem
Precise control and response times of electro-mechanical brakes are limited by static and dynamic parameters such as brake stack stiffness, actuator rotor inertia, and thermal expansion, which current closed-loop control systems struggle to accurately address due to reliance on actuator position feedback from sensors.
Innovation Solution
The implementation of a brake observer and controller system that uses a resolver to measure angular velocity, computes an estimated position signal, and adjusts control inputs based on velocity and position feedback to adaptively manage braking force, incorporating gain values to control convergence and transient response, thereby mitigating the effects of thermal expansion and other parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed-loop control systems use actuator position feedback from sensors, then control precision can be improved, but response time is limited by thermal expansion and static parameters
Solution Approach 1:
The brake observer computes an estimated position signal in advance by integrating the velocity signal, providing predictive position information before actual position measurements are taken. This preliminary computation allows the control system to anticipate position changes and compensate for thermal expansion effects proactively, reducing response time while maintaining control precision.
Solution Approach 2:
The patent introduces a brake observer as an intermediary component that processes velocity signals and generates estimated position signals. This intermediary system bridges the gap between velocity measurements and position control, providing continuous position estimation without relying solely on direct position sensors, thereby improving both precision and response time.
2Manufacturing precision
If actuator position feedback is used for control, then braking force accuracy can be maintained, but thermal expansion effects cannot be adequately compensated
Solution Approach 1:
The system implements feedback by continuously comparing the estimated position signal from the brake observer with the actual position feedback from sensors. This feedback loop enables the controller to detect deviations caused by thermal expansion and adjust control inputs accordingly, maintaining braking force accuracy while compensating for thermal effects in real-time.
Solution Approach 2:
The brake observer dynamically adjusts control parameters based on changing thermal conditions. By integrating velocity signals and comparing estimated positions with actual positions, the system detects thermal expansion parameter changes and modifies control inputs to compensate, maintaining accurate braking force application despite thermal variations.
3Reliability
If direct position sensing is used, then control reliability can be improved, but system complexity and cost increase
Solution Approach 1:
Instead of using complex direct position sensing systems, the patent creates a copied or estimated position signal by integrating velocity measurements through the brake observer. This copied position information provides sufficient control reliability for most applications while significantly reducing system complexity and sensor requirements.
Solution Approach 2:
The brake observer serves multiple functions: it integrates velocity to estimate position, provides predictive position information for control, and enables compensation for thermal expansion effects. This multi-functional approach maintains control reliability while avoiding the need for separate complex position sensing systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the precision and response time of electro-mechanical brakes by effectively compensating for thermal expansion and other factors, improving the accuracy and speed of braking force application.
Implementation Method 1
Based upon a velocity signal from a resolver of the actuator
Implementation Method 2
a brake observer of the brake controller computes an estimated position signal based on the velocity signal
Implementation Method 3
due to thermal expansion of the piston face and/or the pressure plate, the actual separation distance between them may be greater than or less than the designed (i.e., intended) distance
Data Source
AI summary
Methods and apparatus to control electro-mechanical brakes are disclosed. A disclosed example method of controlling a brake actuator comprises receiving a value representative of a velocity of a piston associated with the brake actuator relative to a pressure plate mounted on a wheel, and determining a control input for the brake actuator based on the velocity value.