Lie Group-Based User Motion Refinement Control for Teleoperation of a Constrained Robot Arm

In unilateral teleoperation systems, robots often face challenges when performing tasks with specific geometric constraints. These constraints restrict the robot's movements to certain directions, requiring accurate control of its position and orientation. If the operator's commands do not consider these constraints, excessive contact force may occur, potentially damaging the robot and its environment. Such scenarios can also trigger frequent emergency stops, even with conventional admittance control. To mitigate these issues, we propose a new teleoperation framework tailored for handling geometric constraints. This framework comprises two main components. 1) Geometric Constraint Identification: We use a straightforward line regression method based on Lie group theory to identify geometric constraints. 2) Motion Command Reshaping: The operator's motion commands are safely recalculated using a projection filter coupled with a Lie group setpoint controller. This approach ensures that the robot's movements strictly conform to the identified geometric constraints. As a result, this approach significantly reduces the interaction forces and prevents the risk of severe failures or accidents.