Robot Manipulator Force Control via Spatial Zone Detection
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Solution Overview
Problem
Manipulators, such as robots, pose a risk of injury or damage due to high process forces during operation, especially when interacting with people or obstacles outside their designated working areas, as existing safety measures are inadequate for continuous protection during machining processes.
Innovation Solution
A method that determines the position of a manipulator's working point and reduces applied forces outside a specified process area by adjusting motor load limitations and controller constants, ensuring minimal force application when not within the process area, and increased force application when within it, using sensors and kinematic calculations to define and maintain a safe operational range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high process forces are applied by the manipulator during operation, then machining efficiency and productivity are improved, but the risk of injury to people or damage to obstacles increases
Solution Approach 1:
The control device dynamically adjusts the maximum forces that can be applied by the manipulator based on the detected position of operating points. When operating points are outside the process area, the system limits the maximum applicable forces to prevent injury or damage. When operating points are within the process area, the system allows high forces to be applied for efficient machining. This dynamic adjustment resolves the contradiction between productivity and safety.
Solution Approach 2:
The system applies different force characteristics to different spatial locations. Within the defined process area, the manipulator is allowed to apply high forces for effective machining. Outside the process area, the system imposes force limitations to ensure safety. This spatial differentiation of force properties resolves the contradiction by allowing high forces only where needed for productivity while limiting forces in areas where safety is a concern.
2Object-affected harmful factors
If torque limitation is applied during direct programming to protect people, then safety is improved, but the ability to apply desired high process forces during operation is lost
Solution Approach 1:
The system implements dynamic torque limitation that changes based on the operational mode and position. During direct programming, torque is limited to protect people. During normal operation, when operating points are within the process area, the system allows high torques and forces to be applied for machining. This dynamic switching between limitation modes resolves the contradiction between safety during programming and force capability during operation.
Solution Approach 2:
The control device pre-defines process areas and force characteristics before operation begins. The system establishes spatial zones with different force permissions in advance, allowing operators to program safe paths and boundaries beforehand. This preliminary configuration enables the system to automatically apply appropriate force limitations or permissions during operation without manual intervention, resolving the contradiction between safety and force capability.
Data Source
Figure 1~3
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AI summary
The method involves determining position of an operating point (1.3) and determining whether the position of the operating point lies within a given process area (3) or not. The forces applied in the operating point of the manipulator are reduced, if the position of the operating point does not lies within given process area. Independent claims are included for the following: (1) a control equipment for a manipulator, particularly a robot; and (2) a manipulator, particularly a robot.