Robot Noncontact Sensing for Position-Dependent Object Detection
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Solution Overview
Problem
Industrial robots equipped with noncontact sensors face challenges in accurately detecting moving objects due to environmental disturbances, which can vary depending on the robot's operating position, potentially leading to incorrect detection of objects entering the area.
Innovation Solution
The robot stores reference output values of the noncontact sensor at multiple measurement points within its movable range and compares these with current output values to determine if a moving object is present, using threshold values to adjust motion speed or issue warnings, thereby reducing the influence of environmental disturbances regardless of the operating position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a noncontact sensor is used to detect moving objects, then the robot can detect the presence of objects without physical contact, but the sensor readings are affected by environmental disturbances that vary with operating position
Solution Approach 1:
The system performs preliminary measurement at each operating position to establish reference values before actual detection. The control unit stores reference values for each position, which are then used to compare against current sensor readings during operation, thereby compensating for position-dependent environmental disturbances.
Solution Approach 2:
The system changes the reference parameter (sensor output value) based on the operating position. By adjusting the reference value according to the specific position being occupied by the robot, the system adapts to varying environmental conditions at different locations, maintaining detection accuracy across the workspace.
2Reliability
If the robot stops motion frequently to prevent collisions, then safety is improved, but productivity decreases
Solution Approach 1:
The control unit continuously monitors the noncontact sensor output and compares it against stored reference values. When the difference exceeds a threshold, the system provides feedback to stop motion. This feedback mechanism enables precise collision prevention by responding only to genuine obstacles rather than environmental variations.
Solution Approach 2:
The system applies a threshold-based approach where motion is stopped only when the sensor output difference exceeds a predetermined threshold. This partial action approach avoids unnecessary stops for minor variations while ensuring safety when genuine obstacles are detected, optimizing the balance between safety and productivity.
Data Source
AI summary
A robot with a noncontact sensor is configured to: perform the predetermined motion in a state where the moving object does not enter, and thereby store, for each of a plurality of measurement points set in a movable range of the robot, an output value of the noncontact sensor as a reference output value in advance, and stop the predetermined motion when the output value of the noncontact sensor changes from the reference output value at the measurement point closest to a current operating position of the robot by a first threshold value or larger when the robot is performing the predetermined motion in a state where the moving object could possibly enter and the current operating position of the robot is in a range in which it is necessary to determine an entering state of the moving object.