Robot Torque Sensor Calibration for Accurate Interference Detection
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Solution Overview
Problem
Industrial robots equipped with torque sensors face challenges in maintaining accuracy and calibration, particularly due to distortion or nonlinear characteristics during assembly, which can lead to inaccurate torque detection and interference detection with surrounding objects.
Innovation Solution
An industrial robot system with a controller that includes a moment output unit to calculate and output the moment from the robot's posture and motion, a program storage unit for motion programs, and an output calibration unit to associate torque detection values with moment values, allowing for accurate calibration and contact detection, even with distorted or nonlinear torque sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a torque sensor is incorporated into the robot, then interference detection capability is improved, but measurement accuracy deteriorates due to distortion or nonlinear characteristics during assembly
Solution Approach 1:
The system performs preliminary calibration actions by moving the robot to predetermined positions and storing the relationship between torque sensor output values and arm weight moments. This preliminary calibration data is then used to correct measurement errors during actual operation, resolving the accuracy issue caused by assembly distortion.
Solution Approach 2:
The system establishes a feedback mechanism where the torque sensor output is continuously compared against the stored calibration data (relationship between output values and moments). This feedback loop enables real-time correction of measurement errors, maintaining high measurement precision despite assembly-induced distortion.
2Reliability
If the robot is equipped with torque sensor and control system, then interference detection is enabled, but device complexity increases
Solution Approach 1:
The robot performs self-calibration by automatically moving to predetermined positions and storing its own calibration data without requiring external calibration equipment or complex calibration procedures. This self-service approach reduces system complexity while maintaining detection capability.
Solution Approach 2:
The system simplifies complexity by focusing calibration on key parameters (torque sensor output values and arm weight moments at predetermined positions) rather than attempting to correct all possible distortion variables. This parameter-based approach makes the calibration process manageable despite the inherent complexity of assembly distortion.
Data Source
AI summary
An industrial robot system includes: a robot that includes a torque sensor on at least one rotary shaft; and a controller that controls the robot. The controller includes a moment output unit that outputs a value of moment from a posture of the robot or the posture and a motion of the robot, a program storage unit that stores a motion program, a drive control unit that causes each of component parts of the robot to perform a rotating motion around the rotary shaft in accordance with the motion program, and an output calibration unit that associates a torque detection value detected by the torque sensor with the value of moment output from the moment output unit in the rotating motion of each of the component parts around the rotary shaft performed by the drive control unit.