StereoCNC: A Stereovision-guided Robotic Laser System.

Abstract

This paper proposes an End-to-End stereovision-guided laser surgery system that can conduct laser ablation on targets selected by human operators in the color image, referred as StereoCNC. Two digital cameras are integrated into a previously developed robotic laser system to add a color sensing modality and formulate the stereovision. A calibration method is implemented to register the coordinate frames between stereo cameras and the laser system, modelled as a 3D-to-3D least-squares problem. The calibration reprojection errors are used to characterize a 3D error field by Gaussian Process Regression (GPR). This error field can make predictions for new point cloud data to identify an optimal position with lower calibration errors. A stereovision-guided laser ablation pipeline is proposed to optimize the positioning of the surgical site within the error field, which is achieved with a Genetic Algorithm search; mechanical stages move the site to the low-error region. The pipeline is validated by the experiments on phantoms with color texture and various geometric shapes. The overall targeting accuracy of the system achieved an average RMSE of 0.13 ± 0.02 mm and maximum error of 0.34 ± 0.06 mm, as measured by pre- and post-laser ablation images. The results show potential applications of using the developed stereovision-guided robotic system for superficial laser surgery, including dermatologic applications or removal of exposed tumorous tissue in neurosurgery.