Motor Speed Feedback Control for Gear Transmission Error
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Solution Overview
Problem
Conventional positioning systems fail to adequately suppress variations in the rotation speed of the output shaft of an actuator, leading to unstable behavior of the load connected to it due to angular transmission errors.
Innovation Solution
A motor control system that includes a detection unit for monitoring rotation speed, a speed deviation generation unit, an angular transmission error compensation unit, and a current control unit to correct the speed command and current supplied to the motor, thereby compensating for angular transmission errors and stabilizing the load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional positioning systems correct position commands based on error correction data, then positioning error is corrected, but rotation speed variation of the output shaft cannot be suppressed
Solution Approach 1:
The system introduces speed feedback by detecting the rotation speed of the output shaft and feeding it back to the control unit. The control unit calculates speed deviation between the actual speed and command speed, then adjusts the current command to suppress speed variation. This feedback mechanism directly addresses the inability of conventional positioning systems to control speed variations.
Solution Approach 2:
The system changes the control parameter from position-only correction to include speed deviation correction. By introducing speed as an additional control parameter and adjusting the current command based on speed deviation, the system achieves both positioning accuracy and speed stability that were previously conflicting.
2Device complexity
If angular transmission error is not compensated, then the system configuration remains simple, but load behavior becomes unstable
Solution Approach 1:
The control unit acts as an intermediary that estimates angular transmission error based on speed deviation and uses this estimation to correct the current command. This intermediary approach allows the system to compensate for transmission errors without adding complex mechanical components, maintaining simplicity while improving reliability.
Solution Approach 2:
The system replaces mechanical error compensation mechanisms with an electronic control approach. Instead of using mechanical pre-adjustments or complex gear arrangements to compensate for transmission errors, the system uses electronic estimation and correction of current commands based on detected speed deviations, achieving the same effect with simpler electronics.
3Speed
If speed control is added to position control, then rotation speed variation is suppressed, but control system complexity increases
Solution Approach 1:
The system merges speed control functionality into the existing position control framework by having the control unit perform both position error correction and speed deviation correction in a unified control algorithm. This integration allows speed control to be added without requiring completely separate control systems, thereby limiting the increase in overall complexity.
Data Source
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AI summary
A motor control system that controls a motor (11) by controlling a current supplied to the motor (11) based on a position command input from a host device and controls an operation of a speed reducer (13) including an input shaft (13a) connected to an output shaft (11a) of the motor (11) and an output shaft (13b) connected to a load, the motor control system including: a detection unit (12) that detects an event for detecting a rotation speed of the output shaft (11a) of the motor (11); a speed deviation generation unit (31) that generates a speed command based on the position command and calculates a speed deviation which is a deviation between the speed command and the rotation speed of the output shaft (11a) of the motor (11) detected based on the event detected by the detection unit (12); an angular transmission error compensation unit (34) that estimates an angular transmission error between a rotation angle of the output shaft (11a) of the motor (11) and a rotation angle of the output shaft (13b) of the speed reducer (13), and corrects the speed command, the speed deviation, or the rotation speed of the output shaft (11a) of the motor (11) detected based on the event detected by the detection unit (12), based on the estimated angular transmission error, a current command generation unit (36) that generates a current command based on the speed deviation; and a current control unit (23) that controls a current supplied to the motor (11) based on the current command.