Robot Teaching Control With Dual Force Threshold Collision Sensing
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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 with force detection units and a control unit that moves the end effector based on detected forces, decelerating or stopping when a second force threshold is exceeded, and repeatedly moving in small increments based on first force threshold conditions, to prevent collisions and ensure accurate positioning.
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 divides the force detection function into two independent systems: a first force detection unit (e.g., at the wrist) for teaching operations and a second force detection unit (e.g., at the base) for collision detection. This segmentation allows each detector to be optimized for its specific function, resolving the contradiction between teaching efficiency and collision detection accuracy.
Solution Approach 2:
The patent introduces an intermediary control unit that receives signals from both force detection units and integrates their information. The control unit determines whether to execute teaching movements or stop for collision avoidance by synthesizing inputs from both detectors, enabling both efficient teaching and accurate collision detection without direct conflict.
2Device complexity
If a single force threshold is used for both teaching and collision detection, then system complexity is reduced, but reliability deteriorates due to inability to distinguish teaching forces from collision forces
Solution Approach 1:
The patent applies different force threshold values to different locations: a first threshold for the wrist-mounted detector during teaching and a second threshold for the base-mounted detector during collision monitoring. This local differentiation of parameters allows the system to maintain low complexity while achieving high reliability through context-appropriate threshold settings.
3Device complexity
If force detection is only performed at the wrist, then device complexity is minimized, but collision detection capability near the base is lost
Solution Approach 1:
The patent segments the force detection system into multiple spatially distributed units: one at the wrist for teaching and one at the base for collision detection. This segmentation enables comprehensive monitoring without requiring a single complex omnidirectional sensor, maintaining relative simplicity while improving reliability.
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
The system effectively reduces the likelihood of robot breakage by accurately sensing and responding to forces during teaching, allowing precise movement and reducing teacher load, while maintaining low residual vibration and noise levels.
Implementation Method 1
one or more force detection units that detect a force applied to the movable unit
Data Source
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.