Motor Angular Position Control With Delay-Aware Switching
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Solution Overview
Problem
Motor position control systems face challenges in minimizing overshooting of target angular positions, particularly due to system delays and limitations in motor acceleration, deceleration, and velocity, which affect operational efficiency and accuracy.
Innovation Solution
A motor control method utilizing a proportional controller and a time-optimal controller, where the proportional controller manages rotational speed between a target position and a switching point, and the time-optimal controller takes over beyond the switching point, with the switching point determined to minimize overshoot and maximize speed within system limits, accounting for communication delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a proportional controller is used to control rotational speed near the target position, then positioning accuracy is improved, but the time to reach the target position increases
Solution Approach 1:
The control process is divided into two segments: a first controller (time-optimal) operates when the motor shaft is far from the target position to maximize speed, and a second controller (proportional) operates when the motor shaft is near the target position to ensure accuracy. This segmentation allows each controller to optimize for its specific operating range, resolving the contradiction between speed and accuracy.
2Productivity
If the motor operates at maximum speed to improve productivity, then the time to reach target position is reduced, but overshooting of the target position occurs
Solution Approach 1:
The system determines a switching point in advance where the controller transitions from time-optimal to proportional control. This preliminary determination of the switching point allows the motor to operate at maximum speed initially while ensuring that the transition to accuracy-oriented control occurs at the optimal moment, preventing overshoot.
Solution Approach 2:
The system continuously monitors the rotational position of the motor shaft and uses this feedback to determine when to switch between controllers. The switching point is determined based on feedback about system delay and current position, allowing the system to adjust the transition point to prevent overshooting while maintaining high speed.
3Productivity
If the switching point is set closer to the target position to maximize speed, then productivity is improved, but positioning accuracy deteriorates due to system delay
Solution Approach 1:
The system determines the switching point dynamically based on feedback about system communication delay. By measuring or estimating the delay in the control system, the switching point is adjusted to compensate for this delay, ensuring that the proportional controller engages at the right moment to prevent overshoot while maintaining maximum speed during the earlier phase.
Data Source
AI summary
A motor controller to control rotational speed of an output shaft of an electric motor. The motor controller includes a proportional controller and a time-optimal controller. The proportional controller controls the rotational speed when a present rotational position of the shaft is between a target rotational position and a switching point, inclusively. The time-optimal controller controls the rotational speed when the present rotational position is not between the target rotational position and the switching point. Also introduced herein are aspects pertaining to determining the switching point in a manner that minimizes overshooting the target rotational position while maximizing expediency at which the target rotational position is reached.