Numerical Control Stick Motion Correction via Advanced Timing
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Solution Overview
Problem
Existing methods for correcting stick motion in numerical control machine tools during reversal of movement direction are insufficient, as the timing of correction commands is not early enough, leading to residual stick motion issues.
Innovation Solution
A method that calculates and adds a reversal correction command to the servo motor's speed or torque command based on stored position commands, acceleration, torque, and current errors, determining an advancement time to adjust the correction timing, allowing for precise correction of stick motion before the actual reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a correction command is added based on the control period timing, then the control system operates within standard control cycles, but the correction timing is not early enough to fully eliminate stick motion
Solution Approach 1:
The patent calculates and applies the advancement time to determine when to add the correction command before the actual reversal occurs. By storing position commands and calculating the advancement time based on acceleration and other parameters, the system performs the correction action in advance of the reversal event, ensuring stick motion is eliminated while maintaining proper control timing.
2Manufacturing precision
If the correction command is added too early, then stick motion can be corrected, but the control timing becomes disconnected from the actual reversal moment
Solution Approach 1:
The patent uses feedback from stored position commands, acceleration calculations, and other measured parameters to dynamically calculate the advancement time. This feedback mechanism allows the system to determine the optimal correction timing based on actual system state, ensuring both early correction and accurate reversal timing synchronization.
Solution Approach 2:
The patent changes the timing parameter by calculating an advancement time offset from the reversal moment. This parameter adjustment allows the correction command to be applied at the precise optimal time before reversal, balancing early correction needs with accurate timing requirements.
3Manufacturing precision
If the control period is reduced to improve timing precision, then correction timing can be more accurate, but the control system complexity and processing load increase
Solution Approach 1:
The patent performs preliminary calculation of the advancement time using stored position commands and acceleration data before the reversal occurs. This preliminary action allows the system to determine the optimal correction timing without requiring continuous high-frequency control updates, thus improving precision without proportionally increasing system complexity.
Data Source
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AI summary
A stick motion correction method which corrects stick motion which occurs at the time of reversal of a feed axis of a numerical control machine tool stores a position command to be commanded to a servo motor from an NC program of a numerical control machine tool for each predetermined control period from a current position command to a position command after a predetermined time, calculates a reversal correction command based on the stored position commands, calculates an advancement time for advancing a timing of addition of the reversal correction command to a speed command or torque command of the servo motor from the reversal timing of the servo motor, based on information obtained from operation of the servo motor and adds the reversal correction command to the speed command or torque command of the servo motor to correct stick motion at a timing advanced from the reversal timing of the servo motor by exactly the advancement time. Due to this, it is possible to provide a stick motion correction method which enables correction of stick motion by a high precision.