Development and testing of a compact endoscope manipulator for minimally invasive surgery

Objective: This report describes the design, development, and testing of a novel compact surgical assistant robot to control the orientation and insertion depth of a laparoscopic endoscope during minimally invasive abdominal surgery. In contrast to typical endoscope manipulators, the described robot is particularly compact and lightweight, is simple to set up and use, occupies no floor or operating table space, and does not limit access to the patient in any way. Materials and Methods: The sterilizable endoscope manipulator is sufficiently small and lightweight at 625 g and 110 mm in diameter that it can be placed directly on the abdomen of the patient without interfering with other handheld instruments during minimally invasive surgery. It consists of an annular base, a clamp to hold an endoscope trocar, and two joints which enable azimuth rotation and inclination of the endoscope about a pivot point at the incision. The endoscope insertion depth is controlled by a cable winding acting against a compression spring on the endoscope shaft. Voice recognition and miniature keypad user command interfaces are provided, and the manipulator motors are backdriveable for manual repositioning. Results: Endoscope camera trajectory-following accuracy and response-time results were measured using an optical localizer. Experimental results are given comparing the current prototype with the previous cable-driven prototype. The endoscope manipulator and its user interface were tested and evaluated by several surgeons during a series of minimally invasive surgical training procedures on cadavers and animals. Conclusions: The endoscope manipulator described has been shown to be a viable, practical device with performance and functionality equivalent to those of commercially available models, yet with greatly reduced size, weight, and cost.