Robot Joint Motion Limiting with Physical Stoppers for Task Safety
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Solution Overview
Problem
Conventional robot control technologies fail to ensure safety during task execution, as they rely solely on software control, which can lead to errors and risks, especially when handling heavy objects or using high-risk instruments.
Innovation Solution
A control device with a limitation portion at the joint of a robot that physically limits the motion of links by controlling stoppers attached to actuators, adjusting the movable range based on the task executed, to prevent unintended movements and ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If software control is used to limit robot motion, then the robot can execute tasks with flexibility, but safety cannot be ensured due to potential software errors
Solution Approach 1:
The motion limiting function is segmented into two independent systems: software control for flexibility and mechanical stoppers for safety. The mechanical stoppers are physically attached to the robot links and divide the motion space into allowed and forbidden regions, providing redundant safety protection independent of software reliability.
Solution Approach 2:
Mechanical stoppers are pre-positioned to physically block motion beyond safe boundaries before software errors can cause dangerous movements. The stoppers act as a pre-prepared safety mechanism that passively prevents exceeding motion limits regardless of software state.
2Reliability
If mechanical stoppers are added to physically limit motion, then safety is improved, but device complexity increases
Solution Approach 1:
The mechanical stoppers serve multiple functions: they physically limit motion to ensure safety, define movable ranges for different tasks, and can be repositioned to adapt to various operational requirements. This multi-functionality justifies the added structural complexity.
Solution Approach 2:
The limitation portion acts as an intermediary mechanical element between the actuator and the link, providing a simple yet effective motion boundary without requiring complex control systems. The stopper mechanism is a straightforward mechanical intermediary that translates control intentions into physical motion limits.
3Reliability
If movable ranges are strictly limited by mechanical stoppers, then safety is enhanced, but the robot's operational range is reduced
Solution Approach 1:
The mechanical stoppers are designed to be repositionable rather than fixed, allowing the movable ranges to be dynamically adjusted based on task requirements. The limitation portions can be moved to different positions on the links to expand or contract operational ranges while maintaining safety boundaries for each specific task.
Data Source
AI summary
A control device (120) according to the present application includes a limitation portion that is provided in a joint portion, which joins two or more links, of a robot and that physically limits motion of the links, and a control unit (122f) that limits movable ranges of the links by controlling the limitation portion corresponding to a predetermined joint portion on the basis of a task executed by the robot. With this configuration, it becomes possible to secure safety of when the robot executes a task.