Embedded, miniaturized and distributed control for a colonoscopy robotic platform

Luigi Manfredi, PhD, Alfred Cuschieri, Professor

The Institute for Medical Science and Technology, University of Dundee, UK

CODIR (COlonic Disease Investigation by Robot hydro-colonoscopy) is a five year project funded by the European Research Council for basic and applied research related to the development of a robotic hydro-colonoscopy (RHC) system in order to replace flexible colonoscopy with a patient-friendly system for inspection of the colonic mucosa.

The CODIR’s system is based on filling the colon with a biocompatible warm liquid solution through which an autonomous, flexible, tethered robotic platform will ascend to the caecum. The actual wireless technology cannot stream high quality and reliable video especially in a colon full of saline solution, which reduces the signal transmission due to its conductivity.

The use of a tether greatly improve the streamed video quality, but it would also provide a locomotion resistance related to the number, size, mechanical properties and coating of the wires. This work proposes a control system for a RHC based on a distributed hardware with an ad-hoc bus and communication protocol that: a) reduces the number and the size of the wires keeping a real-time and a safe control on the RHC; b) achieves a miniaturized electronic hardware design; c) because the number and size of the wires are very small which reduce the tether’s resistance, improving the platform’s maneuverability; d) reduces the effort to implement the

locomotion/navigation’s high level control. The hardware design allows the system to be modular and flexible and applicable to a wide variety of surgical robotic systems and applications. Each sensor and actuator has embedded a DSP in order to control the device and to reduce the amount of data exchanged with the main unit’s external control.

Preliminary results
The main control unit, with sizes of 17mm and 35mm, uses a USB interface enabling a real time control of all the actuators and sensors inside the platform. It allows the system to manage and synchronize all the devices, which provides a clock of 1KHz to Matlab that permits the system to be in real-time. The inertial sensory system’s bandwidth is up to 400Hz, has a diameter of 17mm and is composed of 9 sensors (3D accelerometer, 3D gyroscope, 3D magnetometer) with embedded sensors fusion firmware in order to acquire and control the orientation of the platform and to stabilize the camera during the video streaming. The pressure sensory system has a diameter of 6mm and is used to keep the liquid pressure inside the colon under the patient’s acceptable pain level (25mmHg). The system designed allowed to use four wires with a diameter of 0.18mm each, which strongly improve the system’s dexterity.

Preliminary tests suggest that the size and the bandwidth of the system guarantue a real-time control and a design of a platform with an external diameter of 18 mm. Further improvements in the design are still necessary in order to deal with safety issues, to reduce the size of the hardware and to integrate the full HD camera system.
Acknowledgment: Project supported by the European Commission under the FP7, ERC-AG-ID1 ERC, ref. 268519.

Session: Podium Presentation

Program Number: ET003

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