Robot Learning Control for Vibration Suppression
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Solution Overview
Problem
In applications requiring constant speeds, such as laser machining and sealing, vibrations arise due to acceleration/deceleration limitations of motors and reduction gears, leading to poor processing quality and increased work time, as existing methods require trial and error to maintain constant speed without vibration.
Innovation Solution
A robot control system with a sensor for detecting position, a learning control unit that calculates correction amounts to suppress vibrations, and an operating speed change rate adjusting section to optimize speed variations within allowable conditions, allowing the robot to learn and converge on stable operating parameters without human intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If robot operations are accelerated to shorten tact time, then productivity is improved, but vibrations arise in the robot tip due to insufficient rigidity of reduction gears and robot arm
Solution Approach 1:
The patent applies feedback control by measuring vibrations at the robot tip using a sensor and using this information to adjust control commands. The learning control unit stores vibration data and correction amounts, continuously refining control to suppress vibrations while maintaining high-speed operation, thus resolving the contradiction between productivity improvement and vibration suppression.
Solution Approach 2:
The patent changes control parameters dynamically by adjusting operating speed change rates based on measured vibrations. The system learns optimal speed profiles and correction amounts through repeated operations, modifying control parameters to minimize vibrations while maintaining accelerated operation speeds, thereby achieving both high productivity and low vibration.
2Object-affected harmful factors
If learning control is carried out by attaching a sensor to the robot tip and measuring vibrations during operations, then vibrations are suppressed, but work time increases due to required trial and error in teaching operation programs
Solution Approach 1:
The patent implements self-service learning control where the robot system automatically performs learning operations and generates correction amounts without external intervention. The learning control unit autonomously measures vibrations, calculates correction amounts, stores learning results, and applies them to subsequent operations, eliminating the need for manual trial and error teaching and thus reducing work time while maintaining vibration suppression.
3Manufacturing precision
If constant speed is maintained during processing operations, then processing quality is improved, but vibrations arise at corners due to acceleration/deceleration limitations of motors and reduction gears
Solution Approach 1:
The patent applies dynamics by making the operating speed change rate adjustable and adaptive rather than fixed. The system dynamically adjusts speed profiles during operation, particularly at corner positions, by learning optimal speed change rates that maintain constant speed where needed while accommodating acceleration/deceleration limitations at corners, thus preventing vibrations while maintaining processing quality.
4Speed
If sudden acceleration/deceleration is used to keep constant speed at corners, then constant speed is maintained, but vibrations worsen processing quality
Solution Approach 1:
The patent changes control parameters by adjusting operating speed change rates based on learned vibration characteristics. Instead of using sudden acceleration/deceleration, the system learns and applies gradual, optimized speed transitions that maintain constant speed where required while minimizing vibrations at corners, thereby preserving both speed consistency and processing quality.
Data Source
AI summary
A control device repeats learning of: calculating an allowable condition for speed variations during a processing operation based on an allowable condition for processing error; setting an operating speed change rate used to increase or reduce an operating speed of a robot mechanism unit using a calculated allowable condition for speed variations; and, while increasing or reducing the operating speed change rate over a plurality of repetitions within a range not exceeding a maximum value of the operating speed change rate and within a range of an allowable condition for vibrations occurring in a control target, calculates a new correction amount based on an amount of difference between a position of the control target detected based on a sensor and a target position, and a previously-calculated correction amount.