Multi-Joint Robot Arm Control for Synchronized Screw Interaction
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Solution Overview
Problem
Existing robot systems with multi-joint robot arms face challenges in accurately interacting with workpieces due to velocity mismatches between the interactor and the screw, leading to improper screwing or insufficient pressing, which can result in inaccurate interaction.
Innovation Solution
A robot system with a multi-joint robot arm that includes a signal output to provide moving amount signals at fixed time periods, allowing an interaction controller to synchronize the interactor's movement with the workpiece, ensuring accurate and stable interaction by controlling the interactor's velocity and interaction amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the multi-joint robot arm presses the interactor against the screw without velocity synchronization control, then the robot system can operate with simple control, but the interactor velocity will mismatch with the screw velocity causing improper interaction
Solution Approach 1:
The patent implements feedback control by having the interaction controller receive velocity information about the screw movement and adjust the interactor's pressing velocity accordingly. The controller calculates the required interactor velocity based on the screw's rotational velocity and the screw pitch, ensuring synchronized movement between the interactor and screw throughout the fastening process.
Solution Approach 2:
The patent applies dynamics by making the interactor's pressing velocity variable rather than constant. The velocity is dynamically adjusted during the screwing process to match the screw's velocity profile, which changes as the screw penetrates the workpiece. This dynamic velocity matching ensures consistent interaction force and prevents slippage or excessive pressing.
2Reliability
If the interactor velocity is not synchronized with screw velocity, then the control system remains simple, but the interaction becomes unstable and inaccurate
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the velocity profile for the interactor based on the screw pitch and expected screwing speed. Before the actual screwing operation begins, the interaction controller is programmed with the relationship between screw velocity and required interactor velocity, allowing for stable and accurate interaction from the start of the process.
3Manufacturing precision
If the interactor is pressed too much or insufficiently against the screw, then the system can operate without complex sensors, but the screwing quality deteriorates
Solution Approach 1:
The patent applies parameter changes by adjusting the interactor's pressing velocity as a controllable parameter to achieve optimal interaction. By varying the velocity parameter based on the screw's movement, the system maintains proper contact force between the interactor and screw, ensuring precise screwing without requiring complex force sensors or pressure regulation mechanisms.
Data Source
AI summary
A robot system includes a multi-joint robot arm including a plurality of joints; a robot controller configured or programmed to control movement of the multi-joint robot arm; an interactor configured to interact with a workpiece; a signal output configured to output a moving amount signal based on a moving amount of the interactor arranged on a distal end part of the multi-joint robot arm at a fixed time period; and an interaction controller configured or programmed to control interaction of the interactor with the workpiece based on the moving signal output by the signal output.