Collaborative Robot Safety via Dual Force Detection Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In human-collaborative robot systems, hand-guided operations can compromise human safety as the robot does not stop even when contact is made during active hand-guided mode, and frequent false triggering occurs due to included operating force in force sensor readings.
Innovation Solution
A human-collaborative robot system with a first force detection section for external forces and a second force detection section for operating forces, where the safety assurance operation command section compares the net external force (calculated by subtracting operating force from external force) with a threshold, commanding the robot to reduce or stop external forces when exceeding the threshold during hand-guided operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hand-guided operation is activated to allow manual robot operation, then ease of operation is improved, but safety is worsened because the robot will not stop even when contact is made
Solution Approach 1:
The force detection function is segmented into two distinct sections: a first force detection section that detects external forces including contact forces, and a second force detection section that detects only operating forces during hand-guided operation. This segmentation allows the system to differentiate between intentional human operation and unintentional contact, enabling safety functions to remain active during hand-guided operation while still providing safety stops when actual contact occurs.
2Reliability
If the safety assurance function is activated during hand-guided operation to ensure safety, then safety is improved, but productivity is worsened due to frequent false stops
Solution Approach 1:
The operating force detected by the second force detection section is extracted and subtracted from the external force detected by the first force detection section. This extraction removes the intentional human operating force from the safety evaluation, allowing the safety assurance function to operate continuously during hand-guided operation without causing false stops, while still detecting actual contact forces that should trigger safety stops.
3Device complexity
If the force sensor detects both external force and operating force together, then measurement simplicity is improved, but measurement precision is worsened because the operating force is included in the external force detection
Solution Approach 1:
The system dynamically adjusts the force evaluation based on the operation mode. During hand-guided operation, the control device subtracts the operating force detected by the second force detection section from the external force detected by the first force detection section. This dynamic adjustment maintains measurement precision by accounting for the operating force while keeping the physical detection structure simple with only two force detection sections.
Data Source
AI summary
A human-collaborative robot system includes a first force detection section that detects external force acting on a robot; a second force detection section that detects only an operating force acting on the robot when a human manually operates the robot; and a safety assurance operation command section that, in the case where the external force detected by the first force detection section exceeds a predetermined threshold value, commands a safety assurance operation of causing the robot to move in a direction that reduces the external force or causing the robot to stop. When the human is manually operating the robot while the robot is in the stopped state, the safety assurance operation command section compares a value obtained by subtracting the operating force detected by the second force detection section from the external force detected by the first force detection section with a predetermined threshold value.