Robot Arm Impedance Control for Object Stability
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Solution Overview
Problem
Conventional robot arm control systems fail to prevent tilting and falling of objects during object transportation, especially when the person's posture is poor or when handling hard or sharp objects, due to insufficient force or bad posture leading to misoperation.
Innovation Solution
A control device and method for a robot arm that acquires working posture information and calculates a degree of danger, increasing the robot arm's rigidity accordingly to maintain stability and prevent tilting or falling, by adjusting mechanical impedance based on the calculated danger level and object characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot arm operates with high flexibility and low restoring force to ensure safety during human-robot cooperation, then safety is improved, but operation precision deteriorates when small forces are applied
Solution Approach 1:
The patent applies dynamics by making the robot arm's impedance characteristics changeable in real-time based on operational conditions. The control device dynamically adjusts the restoring force generated by the robot arm depending on the detected operation state, allowing the system to transition between high flexibility (for safety) and high precision (for accurate manipulation). This dynamic adaptation resolves the contradiction by allowing both safety and precision to be achieved at different times as needed.
Solution Approach 2:
The patent changes the physical parameters of the robot arm's mechanical impedance based on operational requirements. By detecting operation state and accordingly adjusting the restoring force parameter, the system can maintain high precision when small forces are needed while ensuring safety through low restoring force when humans are closely interacting. This parameter change strategy allows the robot arm to adapt its characteristics to different operational contexts.
2Ease of operation
If the robot arm maintains low restoring force to accommodate human operation, then ease of operation is improved, but stability deteriorates causing misoperation due to trembling hand or insufficient force
Solution Approach 1:
The control device changes the restoring force parameter based on detected operation states. When the system detects that the human operator is experiencing difficulty (trembling hand, insufficient force, bad posture), it dynamically adjusts the restoring force to provide appropriate support, thereby maintaining both ease of operation and stability simultaneously.
Solution Approach 2:
The patent implements feedback by continuously detecting the operation state (including human posture, applied forces, and operation conditions) and using this information to adjust the robot arm's restoring force in real-time. This closed-loop control ensures that the robot arm provides appropriate support to maintain stability while preserving ease of operation for the human user.
3Adaptability or versatility
If the robot arm operates with flexible impedance to allow human cooperation, then adaptability is improved, but reliability deteriorates when handling hard or sharp objects causing burden on the person
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the impedance parameters of the robot arm based on the type of object being handled and the operation conditions. When handling hard or sharp objects, the control device increases the restoring force to provide adequate support and prevent burden on the human operator, while maintaining adaptability for different object types through real-time parameter adjustment.
Solution Approach 2:
The system uses dynamics to adapt its impedance characteristics in real-time based on operational requirements. The control device detects operation state and dynamically changes the robot arm's restoring force, allowing the system to be adaptable to different objects (including hard and sharp ones) while maintaining reliability by providing appropriate support when needed.
Data Source
AI summary
A control device for a robot arm is designed such that, based on information on a transportation state database in which information on a transportation state of a person operating the arm is recorded, an impedance setting unit sets a mechanical impedance set value of the arm, and an impedance control unit controls a mechanical impedance value of the arm to the mechanical impedance set value thus set.