High precision robotic system design for microsurgical applications.

The introduction of robotic systems in medical surgery has achieved the goal of decreasing procedures invasiveness positively impacting the patient’s prognosis by reducing the incisions size, surgical infections, and hospitalization time. Nowadays robotic surgery is used as an integral part of urology, gynaecology, abdominal and cardiac interventions. Despite its adoption in several surgical specialties, robotic technology remains limited in microsurgery. These limitations arise from the fact that most commercial medical robots achieve millimetre precision levels, being unsuitable for manipulating fine structures with dimensions <0.8mm such as blood vessels.

In this paper, we present the development of a robotic system providing sub-millimetre motion resolution for the potential manipulation of fine structures. The design is based on a linear delta robotic geometry consisting of three linear actuators, three pairs of parallel legs and twelve spherical joints, enabling high stability, low inertia, and high motion precision all required for microsurgical tasks. The motion, resolution and repeatability of the developed system were experimentally tested.

Our results showed that the proposed design motion resolution is 3.37 ±0.3μm in both the X and Y axes and 1.32 ±0.2μm in the Z axis considering individual steps. We tested the system considering hexagon and serpentine trajectories with dimensions similar to those found in blood vessels, we found that performing the same trajectory for five times showed a displacement between these. For the hexagon path, the migration occurs in its lower section, with a displacement error of 9 ±1.35μm. Similarly, for the serpentine path, an error of 40 ±2.13μm occurs between adjacent lines. Though the addition of displacement and angle compensation these errors were reduced by 39.6% and 85.9%, for the hexagon and serpentine trajectories respectively. These results demonstrate the potential use of the here presented robotic system for its application in neurosurgery, plastic, and breast cancer surgery.