Development Of Micro-robot For The Active Exploration Gastrointestinal Track

A miniature robot for intestinal inspection was developed to resolve the main problems of clinical conventional push-type gastrointestinal endoscope and capsule endoscope, which gave a new way for intestinal inspection and diagnosis with minimal invasion or non-invasion. For the gut environment, a highly efficient drive micro-mechanism has been designed according to the requirements that robots can be swallowed. Combining with other research programs in this laboratory----wireless communicating and powering technology, we overcome the difficulty which prevents the robot from going further into body.When we begin to develop the GI capsule robot, it's a primary problem to choose a movement pattern. Based on the analysis of environmental characteristics of human intestine, the status of the development on gastrointestinal tract robot is introduced firstly. Then advantages of several main movement patterns are analyzed and compared. At last, from the point of dynamics and human security, we carry out comparative analysis between foot-like movement and earthworm movement, pneumatic drive and mechanical drive, locomotion using impact and one using friction. And a solution about inchworm-like movement is chosen based on hydraulic drive and two DC brushless motors.The capsule uses two brushless DC motors to realize the motion of forward, backward, stopping and other movements. In order to overcome the conflicts between hydraulic drive and the "wireless", the pump of capsule compresses forwards one time to inflate one gasbag and suction the other gasbag into a vacuum; then the pump compresses in back to suction this gasbag into a vacuum and to inflate the other gasbag. The pump and gasbags are specially designed and fabricated for the capsule. Special note is the volume of the two gasbags is same, half of the total volume available in the pump; a latex gasbag with soft gills is able to obviously increase the friction with the digestive track. Cooperating with other research groups, wireless communication sub-module and wireless power supply sub-module are designed for the capsule system. Then a controlling module which includes MCU, DC brushless motor driver and simulative switch is developed together. All of the PCB modules and the movement mechanism make the'wireless'and uninterrupted power supply come true. The contracted capsule prototype is 40 mm in length, 13 mm in diameter and 13g in weight.We designed several groups of experiments to test performance with the motorized endoscopic robot. Experiments results demonstrate that the micro-robot can travel with a speed 45mm/min in a soft plastic pipe and with a typical speed ranging between 10 and 30 mm/min in the digestive track.