Selective Joint Torque Control for Robot Force Precision
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Solution Overview
Problem
Existing control systems for serial robotic systems face computational challenges when controlling the force applied by joints, especially when operating in torque mode, which is more computationally expensive than position mode.
Innovation Solution
The method involves using a processor to detect contact between a tool and a surface, identifying a specific joint to control torque, and sending a command to switch the joint motor to torque mode, allowing the joint to apply a calculated torque value while other joints continue to operate in position mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If torque mode control is applied to multiple joints for force control, then force control precision is improved, but computational cost increases
Solution Approach 1:
The patent segments the control approach by applying torque mode to only the specific joint that is in contact with the surface, while keeping other joints in position mode. This selective segmentation reduces the number of joints requiring computationally expensive torque control, thereby lowering overall computational cost while maintaining force control precision where needed.
Solution Approach 2:
The patent applies local quality by implementing torque mode control locally at the contact joint rather than globally across all joints. The control system identifies the specific joint experiencing contact force and applies torque control only to that joint, optimizing computational resources by providing high-precision force control only where contact occurs.
2Force
If torque mode is used for force control, then force application capability is improved, but system complexity increases
Solution Approach 1:
The patent implements dynamic switching between position mode and torque mode based on real-time contact detection. The control system dynamically adapts by transitioning the contact joint to torque mode when contact is detected and maintaining other joints in position mode, thereby optimizing force application capability while managing system complexity through adaptive, condition-based control.
Solution Approach 2:
The patent extracts the torque control function from the global control system and applies it selectively to only the contact joint. By taking out torque mode from the universal control approach and applying it locally where needed, the system maintains force application capability while reducing overall control system complexity compared to applying torque mode to all joints.
Data Source
AI summary
A method includes using at least one processor to detect that a tool coupled to an end effector of a robot having multiple joints is contacting a surface. The robot includes multiple joint motors configured to control multiple motions of the multiple joints. One or more control systems are configured to control each of the joint motors in a joint position mode. The method also includes identifying, via the at least one processor, a first joint of the multiple joints in response to detecting that the tool is contacting the surface. The method also includes sending, via the at least one processor, a command to at least one of the one or more control systems associated with a first joint motor of the multiple joint motors that corresponds to the first joint. The command is configured to cause the at least one of the one or more control systems to operate in a torque mode. The method also includes sending, via the at least one processor, a joint torque value to the at least one of the one or more control systems. The at least one of the one or more control systems is configured to cause the first joint to apply the joint torque value via the first joint motor.