Co-Handling Robot Force Control for Transparent Body Interaction
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Solution Overview
Problem
Existing industrial robots with insufficiently transparent or irreversible joints face challenges in co-handling tasks due to mechanical friction, inertia, and interaction limitations, leading to complex designs, high costs, and difficulty in mastering the systems.
Innovation Solution
A co-handling robot with a multiaxis force sensor and a modified force-increasing control law that amplifies operator forces at the tool while reducing joint friction, allowing sensitive interaction with the robot body without altering its mechanical architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a force-increasing control law is applied to amplify operator forces at the tool, then force amplification is achieved, but joint friction increases and transparency deteriorates
Solution Approach 1:
The control law is segmented into distinct functional loops: an outer force-increasing loop that amplifies operator forces, and inner transparency loops that compensate for joint friction and maintain transparency. This segmentation allows each loop to address specific requirements independently, resolving the contradiction between force amplification and friction reduction.
Solution Approach 2:
The control system introduces intermediary compensation mechanisms that act as mediators between the force-increasing function and the transparency requirement. The friction compensation loop serves as an intermediary that counteracts the harmful friction effects generated by the force-increasing loop, allowing both functions to coexist.
2Ease of operation
If the robot system is made mechanically transparent to allow free movement, then co-handling quality improves, but the ability to interact with the robot body deteriorates
Solution Approach 1:
The control system applies different transparency characteristics to different parts of the robot system. The tool interaction interface maintains high transparency for smooth co-handling, while the robot body interactions preserve natural force feedback. This local differentiation of transparency quality allows both co-handling ease and interaction capability to be optimized simultaneously.
3Manufacturing precision
If industrial robots with irreversible joints are used, then positioning precision is improved, but co-handling capability deteriorates due to joint locking
Solution Approach 1:
The patent replaces the mechanical reversibility requirement with a control-based solution. Instead of modifying the irreversible mechanical joints, a control law is implemented that mathematically compensates for the irreversibility effects, allowing co-handling operations with irreversible joints while maintaining positioning precision.
Data Source
AI summary
A co-handling robot has a mixed-forced control law providing high effector sensitivity and enabling interaction with the body of the robot. A multi-axis force sensor is carefully positioned between the end member (flange) of an industrial co-handling robot and the tool supported thereby. A modified increased force control law is implemented in the robot controller by introducing a saturation function.