Servo Control Device Friction Correction for Tracking Accuracy
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Solution Overview
Problem
Conventional servo control devices fail to adequately correct tracking errors caused by friction, especially when the feed drive mechanism is stopped temporarily during movement in the same direction, leading to increased errors when reversing direction.
Innovation Solution
A servo control device with a moving-state determination unit, a correction-amount selection unit, and an addition unit that simulates the motor's response to determine the moving state and adjusts the drive command with a correction amount to account for friction changes, ensuring accurate tracking even when the motor is stopped temporarily.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If correction is performed only when speed command value sign is reversed, then the device complexity is reduced, but tracking error occurs when feed drive mechanism is stopped temporarily during movement in the same direction
Solution Approach 1:
The patent applies preliminary action by determining the moving state in advance through motor response simulation before actual motion occurs. The moving-state determination unit simulates motor response to predict whether the feed drive mechanism is actually moving, and correction is applied proactively based on this prediction rather than reactively after errors occur. This resolves the contradiction by adding a predictive layer that maintains accuracy without requiring complex real-time monitoring during motion.
Solution Approach 2:
The patent implements feedback by using the simulated motor response as a virtual sensor to determine moving state. The moving-state determination unit continuously simulates motor response and feeds back the determined moving state to the correction amount selection unit, which adjusts correction amounts accordingly. This feedback mechanism enables accurate tracking by continuously adapting correction based on predicted actual motion state, resolving the issue of uncorrected errors during temporary stops.
2Manufacturing precision
If correction amount is increased to account for friction changes, then tracking error is reduced, but the correction amount becomes excessive when feed drive mechanism is stopped temporarily before reversing direction
Solution Approach 1:
The patent applies preliminary action by simulating motor response in advance to determine the actual moving state before correction is applied. By predicting whether the mechanism is truly moving or temporarily stopped through motor response simulation, the system can proactively select appropriate correction amounts, preventing both under-correction and over-correction scenarios.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the correction amount based on the determined moving state. When the moving state indicates actual motion, full friction correction is applied; when the moving state indicates temporary stop, reduced or zero correction is applied. This dynamic parameter adjustment resolves the contradiction by adapting correction magnitude to the actual physical state, eliminating over-correction while maintaining accuracy.
3Manufacturing precision
If friction correction is applied continuously, then tracking accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent applies preliminary action by using motor response simulation to predict actual motion state before applying correction. This predictive approach allows correction to be applied only when and where needed, rather than continuously, thereby reducing energy consumption while maintaining tracking accuracy during critical motion phases.
Solution Approach 2:
The patent implements partial action by applying friction correction selectively based on the determined moving state rather than continuously. Correction is applied partially or fully only when the simulated motor response indicates actual motion is occurring, and reduced or omitted when temporary stops are detected, optimizing the balance between accuracy and energy efficiency.
Data Source
AI summary
A servo control device including a servo control unit that calculates a drive command that causes a feedback position from a motor to be driven to follow a command position, to drive the motor according to the drive command, a moving-state determination unit that determines a speed of the motor is by simulating a response of the motor, and outputs a determination result as a moving state, a correction-amount selection unit that selects a correction amount according to a change pattern of the moving state at a timing when the determined moving state changes, and an addition unit that adds the correction amount output from the correction-amount selection unit to the drive command calculated by the servo control unit to generate a corrected drive command, and sets the corrected drive command as a drive command to the motor instead of the drive command calculated by the servo control unit.