Robotic Relay of Free-Space Optical Beams for Medical Applications
Guangshen Ma, Patrick Codd, Mark Draelos
AI summary
Problem
Conventional fixed-base galvanometer or robot-mounted laser systems lack the scanning flexibility and workspace coverage needed for complex 3D medical procedures like full-view tissue scanning or navigating around anatomical obstacles.
Approach
The authors introduce an N-mirror-N-robot framework that uses robot-mounted steering mirrors to direct free-space laser beams, supported by a novel kinematics model, optimization-based calibration, and a prototype validated with an RGB-D camera.
Key results
- Development of an N-mirror-N-robot kinematic framework for 3D laser beam planning
- A system calibration method estimating laser origin, camera pose, and mirror geometry via nonlinear optimization
- Prototype demonstration achieving ~2.0 mm average object tracking error limited by camera depth accuracy
- Simulation and experimental validation confirming feasibility for tracking paths, markers, phantoms, and real tissue
Why it matters
Enables precise, non-contact laser manipulation in space-restricted medical environments, paving the way for advanced multi-mirror surgical and diagnostic platforms.
Abstract
Medical robotic laser systems require high preci- sion beam steering and sensor integration to support diverse applications, ranging from surgical intervention to optical tis- sue diagnostics. While conventional galvanometer-based mirror systems offer high-fidelity control, their fixed-base architecture limits their utility in procedures requiring broad coverage or large angular ranges, such as 360-degree full-view scanning. To expand imaging flexibility, we propose a novel robot- mirror framework to use robot-attached mirrors to control a 3D free-space laser beam, which is referred to as “N- mirror-N-robot system” where N is the number of mirrors and robots. This framework allows for general laser beam planning to trace 3D targets by using multiple robot-and-mirror combinations. We develop a prototype for the special case with a single mirror attached to the robot (N = 1). This prototype integrates an RGB-D depth camera for object tracking, a 6- DOF robot-attached mirror, and a laser diode source. We propose a computational framework for system kinematics and calibration. Simulation and real experiments are conducted to track specified paths, markers, phantoms, and real tissue to verify the system feasibility. The results show an average object tracking error of approximately 2.0 mm that is close to the depth accuracy of the camera. This N = 1 prototype shows promise for N > 1 case and the potential for general 3D laser planning under arbitrary geometric constraints.