Estimating Mechanical Play in Electromechanical Actuators
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Solution Overview
Problem
Current methods for monitoring the mechanical play in electromechanical actuators, such as those used in aircraft, are costly and lack a rapid and effective means to evaluate the amplitude of play, which is crucial for defect detection and health monitoring.
Innovation Solution
A method utilizing a state observer with a Kalman filter to estimate the amplitude of mechanical play by measuring the position and load of an electromechanical actuator's motor and mobile element, considering play as a component of the state, and calculating the amplitude from dynamic variable values using a discrete state observer model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a non-linear estimator based on Kalman filter is used to model play amplitude, then measurement precision of play amplitude is improved, but device complexity and resource consumption increase
Solution Approach 1:
The patent replaces complex mechanical play measurement systems with an electronic state observer based on Kalman filtering. The state observer uses electrical signals from position and load sensors to estimate mechanical play amplitude, substituting direct mechanical measurement with computational estimation that achieves high precision without complex mechanical instrumentation.
Solution Approach 2:
The patent transforms the play characterization problem from direct mechanical measurement to estimation of state parameters through a mathematical model. By representing play as a state variable in a dynamic system model and using Kalman filtering to estimate this state from measurable parameters (position, load), the system achieves accurate play amplitude measurement while keeping the physical system simple.
2Reliability
If comprehensive sensors and state observer are implemented for play estimation, then reliability of actuator monitoring is improved, but ease of operation and resource requirements worsen
Solution Approach 1:
The state observer system is designed to automatically estimate play amplitude using existing sensor data from the actuator's normal operation. The Kalman filter continuously processes position and load measurements to self-update play estimates without requiring manual intervention, specialized operating procedures, or additional complex instrumentation, thereby maintaining ease of operation while improving reliability.
3Productivity
If continuous monitoring of play amplitude is performed using state observer, then productivity of defect detection is improved, but loss of energy and computational resources increases
Solution Approach 1:
The state observer enables continuous estimation of play amplitude during normal actuator operation by continuously processing sensor measurements through the Kalman filter algorithm. This continuous monitoring provides real-time defect detection capability without requiring separate testing phases or interrupting actuator operation, thereby improving productivity while keeping computational demands manageable through efficient recursive estimation.
Data Source
AI summary
A method is provided for characterizing the amplitude of play in an electromechanical actuator comprising an electric motor, a movable element, an upstream sensor, a downstream sensor, and a force sensor. The method includes steps of measuring the position of the motor, the position of the movable element and the load applied to the movable element using the three sensors. On the basis of a computer model of the actuator and of the measurements, a value of the amount of mechanical play is estimated using a state observer considering the play to be a state component. The amplitude of the play is determined from a set of values of the dynamic variable obtained in the preceding step at various times.