Robot Arm Torque Control for Easier Lead-Through Stopping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing control devices for arm robots during lead-through operations face difficulties in stopping the arm easily due to estimation errors in motor torque and lack of appropriate load generation for the operator, leading to instability and potential risks.
Innovation Solution
A control device with a torque generation control unit that cancels friction in each axis and a torque changing unit that adjusts the canceling torque based on speed feedback, allowing for easier stopping and appropriate load generation during lead-through operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If friction is completely counteracted by canceling torque, then the arm moves smoothly during lead-through, but the arm becomes difficult to stop and inappropriate load is generated to the operator
Solution Approach 1:
The control device dynamically adjusts the friction canceling torque based on the arm's speed. When the arm is moving, full friction compensation is applied for smooth operation. When the arm approaches stopping, the friction compensation is reduced, allowing the operator to easily stop the arm while maintaining stability. This dynamic adjustment resolves the contradiction between smooth movement and easy stopping.
Solution Approach 2:
The control device changes the parameter of friction canceling torque from a constant value to a variable value that depends on arm speed. By modifying this parameter based on operational conditions, the system achieves both smooth movement during operation and easy stopping when needed, while generating appropriate load for the operator.
2Ease of operation
If friction is completely counteracted, then lead-through operation is smooth, but estimation error causes difficulty in stopping and excessive load to operator
Solution Approach 1:
The control device uses speed feedback from the arm's motion to adjust the friction canceling torque. The speed detection unit continuously monitors arm speed and feeds this information back to the control unit, which then adjusts the torque accordingly. This feedback mechanism reduces the impact of estimation errors and prevents excessive load on the operator while maintaining smooth operation.
Data Source
AI summary
To provide a control device of a robot having an arm which causes the arm to be stopped more easily than conventionally by generating a load of appropriate magnitude to an operator during lead-through. The present invention relates to a control device of a robot having an arm, the control device including: a motor that generates torque in each axis of the robot; a torque generation control unit that controls the motor so as to generate a canceling torque which cancels friction of each axis of the robot when controlling the robot by external force tracking; and a torque changing unit that changes the canceling torque to a reference value or less.