Electromechanical Actuator Control for High-Inertia Motor Reversal
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Solution Overview
Problem
High-power electromechanical actuators with high inertia electric motors face challenges in achieving quick response and reversal due to excessive current requirements, as standard feedback controls are inadequate for high-frequency motor speed reversals.
Innovation Solution
A control system that determines the command time and stop time for an electromechanical actuator, using position sensors and motor rotational speed to calculate deceleration and compare it with available current, allowing for predictive deceleration of the electric motor to ensure accurate positional control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If standard feedback controls are used for high-frequency motor speed reversals, then the actuator can change direction, but excessive current is required beyond motor design limits
Solution Approach 1:
The controller predicts the stop time required to halt motor movement before the reversal is commanded. By comparing this predicted stop time with the time available before the next command, the system performs preliminary deceleration actions to ensure the motor can reverse direction without exceeding current limits. This predictive approach allows high-frequency reversals while maintaining current consumption within safe operating boundaries.
2Device complexity
If the motor is designed for constant speed applications, then the motor structure is simplified, but the high inertia prevents quick response and direction changes
Solution Approach 1:
The controller continuously monitors motor position, speed, and operational state through feedback from sensors. Using this real-time feedback, the controller calculates predicted stop times and adjusts deceleration commands dynamically. This feedback mechanism enables the high-inertia motor to respond quickly to direction changes by optimizing the deceleration profile, effectively compensating for the motor's inherent slowness without requiring a redesign of the motor itself.
Solution Approach 2:
The control system dynamically adjusts the deceleration rate based on real-time motor state and command timing requirements. Rather than using a fixed deceleration profile, the system modifies acceleration and deceleration rates adaptively, allowing the motor to optimize its response time for each specific operational context while maintaining structural simplicity.
3Measurement precision
If the motor decelerates earlier to allow for stopping before position reversal, then response accuracy improves, but the effective operational time is reduced
Solution Approach 1:
The controller changes the timing parameters of deceleration based on the predicted stop time and command interval. By dynamically adjusting when deceleration begins and at what rate, the system optimizes the balance between achieving accurate positioning and maximizing the effective operational time. This parameter optimization ensures that the actuator reaches the commanded position accurately while minimizing unnecessary idle time between operations.
Data Source
AI summary
A method of operating an electromechanical actuator (EMA) system includes determining a command time remaining for an actuator to attain a commanded position and determining a stop time required to stop movement of the actuator. The command time is compared to the stop time, and an electric motor driving the actuator is decelerated if the stop time is equal to or greater than the command time. An electromechanical actuator system includes an actuator and an electric motor operably connected to the actuator, the electric motor configured to drive movement of the actuator. A controller is operably connected to the electric motor to control operation of the actuator. The controller is configured to determine a command time remaining, determine a stop time, compare the command time to the stop time, and decelerate the electric motor if the stop time is equal to or greater than the command time.