Robot Teaching Force Control for Collision Detection Near the Base
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Solution Overview
Problem
Existing robot teaching methods using external force detection struggle to accurately sense collisions near the base, leading to potential robot breakage due to inadequate force threshold settings and collision detection mechanisms.
Innovation Solution
A robot system equipped with force detection units and a control unit that adjusts movement based on detected forces, decelerating or stopping the end effector when a second force threshold is exceeded, and intermittently moving the end effector according to applied forces, reducing the risk of collision and robot damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the robot hand moves in a fixed amount due to short-time external force application, then teaching efficiency is improved, but collision detection accuracy near the base deteriorates
Solution Approach 1:
The patent segments the force detection function into two distinct threshold levels: a first force threshold for normal teaching operations and a second force threshold for collision detection. This segmentation allows the system to differentiate between intentional teaching forces and harmful collision forces, resolving the contradiction by enabling both efficient teaching movement and accurate collision detection near the base.
Solution Approach 2:
The patent changes the force threshold parameter dynamically based on the detected force magnitude. When the detected force exceeds the second threshold, the system immediately stops the teaching movement, preventing collision damage. This parameter change strategy allows the system to maintain high teaching efficiency during normal operations while providing robust collision protection when needed.
2Measurement precision
If force threshold is set low for accurate collision sensing, then collision detection sensitivity is improved, but false detection increases causing interrupted teaching
Solution Approach 1:
The patent divides the force detection range into two segments using dual thresholds: the first threshold handles normal teaching force variations, and the second threshold detects actual collisions. This segmentation prevents false detections during normal teaching while maintaining high sensitivity for real collision events, thus preserving teaching continuity.
Solution Approach 2:
The system implements feedback control by continuously monitoring the detected force and comparing it against the second threshold. When the force exceeds this threshold, the system provides immediate feedback by stopping the teaching movement, preventing both false interruptions and actual collision damage.
3Reliability
If force threshold is set high to avoid false detection, then teaching continuity is maintained, but collision detection accuracy deteriorates
Solution Approach 1:
The patent segments the force threshold into two levels: a lower first threshold for normal operations and a higher second threshold for collision detection. This segmentation ensures that teaching continuity is maintained during normal operations while collision detection accuracy is preserved at the higher threshold level.
Solution Approach 2:
The system prepares for potential collisions by pre-setting the second force threshold and the corresponding stop condition. This preliminary action ensures that when a real collision occurs, the system can immediately detect and respond to it, maintaining both teaching continuity and collision detection accuracy.
4Ease of operation
If the robot operates in compliance control mode for direct teaching, then ease of operation is improved, but collision protection capability deteriorates
Solution Approach 1:
The patent implements feedback control by continuously monitoring the detected force during compliance control operations. When the force exceeds the second threshold, the system provides immediate feedback by switching from compliance control to position control and stopping the movement, thus maintaining ease of operation while providing robust collision protection.
Solution Approach 2:
The system dynamically switches between compliance control mode for ease of operation and position control mode for collision protection. This dynamic control strategy allows the robot to operate freely during normal teaching while automatically providing rigid protection when collision risks are detected.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances accurate movement and reduces the likelihood of robot breakage by effectively sensing and responding to applied forces, allowing precise positioning while minimizing residual vibrations and teacher fatigue.
Implementation Method 1
one or more force detection units that detect a force applied to the movable unit
Data Source
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AI summary
When a first condition that a time in which magnitude of a first detection force detected by a force detection unit is larger than a first force threshold value continued for a time longer than zero and shorter than a first time threshold value is satisfied in teaching, a movable unit is moved in a predetermined amount in a direction according to a direction of the first detection force. When a second condition that magnitude of a second detection force detected by the force detection unit is larger than a second force threshold value that is larger than the first force threshold value is satisfied during movement of an end effector, the movable unit is decelerated or stopped.