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Robotic-assisted surgery systems like the Medtronic HUGO platform place motors and control electronics at the distal end of the arm, resulting in high distal mass, large inertia, and the need for a heavy 500 lb counterweight. This increases system footprint, makes repositioning difficult, and contributes to operating room staff fatigue.
This project investigates a pneumatic surgical drive architecture that relocates the distal mass to a compact base module. It is a feasibility study on position-controlled pneumatic actuators as a potential solution for future robotic surgical systems. It demonstrates that pneumatic actuators can replicate current motor-driven systems by achieving precise position control while withstanding dynamic loads. This approach leads to a reduction in weight at the distal end of the robotic arm.
This project is conducted in collaboration with Medtronic to implement a remote pneumatic drive architecture for their surgical robotic arm, relocating actuation components to the base to reduce distal mass and system footprint. Hydraulic, pneumatic, and tendon-driven actuation concepts were evaluated through system-level analyses and decision matrices, resulting in the selection of a pneumatic solution based on performance, controllability, and integration feasibility. The pneumatic actuator operates on a closed-loop position control system, enabling precise intermediate stroke positioning rather than traditional bang-bang actuation, a critical requirement for repeatable, safe tissue interaction in a surgical environment.
In parallel, a custom force-feedback test rig was designed and built to validate system performance under dynamic loading conditions. The rig features a load cell, motor driver, and embedded electronics running a closed-loop force control loop with a three-range PID gain scheduling strategy — separate tunings for low, mid, and high force regimes — to account for the changing dynamics of a pneumatic load across its operating range. The system achieves sub-100 ms response times and settles within one second across a 0 to 50 pound operating range, meeting the performance targets defined for a bench-top surgical proof-of-concept.
Full test fixture for pneumatic actuator feasibility study
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