Collaborative Robot Contact Force Threshold Control
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Solution Overview
Problem
Existing human-collaborative robot systems fail to provide a sense of safety to workers when contact is detected, as they either perform sudden stops that may be perceived as threatening or do not adequately ensure safety in shared working spaces.
Innovation Solution
A human-collaborative robot system that includes detection units to measure physical quantities such as force, torque, or vibration upon contact, with a stop command unit that compares these values to threshold levels to selectively implement either a quick or slow stop, ensuring safety and reducing worker anxiety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot performs a sudden stop when contact is detected, then the safety of the robot and surrounding environment is ensured, but the worker may feel threatened and work is disturbed
Solution Approach 1:
The patent applies parameter changes by varying the stop method based on the magnitude of contact force detected. When contact force is below a threshold, a slow stop method is used to maintain worker comfort; when contact force exceeds the threshold, a quick stop method is used to ensure safety. This dynamic parameter adjustment resolves the contradiction between safety and worker comfort.
2Ease of operation
If the robot performs a slow stop to give a sense of safety to the worker, then worker comfort is improved, but the safety of the robot and surrounding environment may be compromised
Solution Approach 1:
The system dynamically changes the stop parameter based on contact force magnitude. A threshold value is set for contact force, and the stop method is selected accordingly: slow stop for minor contacts to maintain worker comfort, and quick stop for severe contacts to ensure safety. This resolves the contradiction by making the stop behavior adaptive rather than fixed.
3Reliability
If the robot always performs a predetermined stop operation when contact is detected, then safety is ensured, but the worker's work is disturbed even when there is little risk
Solution Approach 1:
The patent introduces a threshold-based parameter change mechanism where the stop operation type is determined by comparing contact force magnitude against a predetermined threshold. For contact forces below the threshold, a slow stop is performed that minimizes disruption to work flow. For contact forces above the threshold, a quick stop is performed to ensure safety. This adaptive approach maintains safety while reducing unnecessary interruptions.
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 balances safety by quickly stopping the robot in severe contact situations while providing a sense of safety by slow stopping in less severe cases, enhancing the overall safety environment for both the robot and human workers.
Implementation Method 1
a detection unit configured to directly or indirectly detect a physical quantity which is changed in response to contact force applied to the robot
Implementation Method 2
the physical quantity is force or torque applied to the robot from the external environment
Data Source
AI summary
A human-collaborative robot system includes a detection unit that directly or indirectly detects a physical quantity which is changed in response to contact force applied to a robot when the robot comes in contact with an external environment, and a stop command unit that compares the physical quantity detected by the detection unit with a first threshold value and a second threshold value greater than the first threshold value, stops the robot according to a predetermined stop method when the physical quantity is equal to or greater than the first threshold value and is smaller than the second threshold value, and stops the robot in a shorter period of time as compared with the predetermined stop method when the physical quantity is equal to or greater than the second threshold value.