Development of a legged capsule for the gastrointestinal tract: an experimental set-up

The experimental study reported in this paper illustrates the development of a legged locomotion system for autonomous medical microrobots with the final goal to perform gastrointestinal (GI) diagnosis by minimally invasive endoscopy. An active teleoperated diagnostic capsule should be able to adapt its gait to changing gut diameters and vary its patterns to turn, rotate or stop based on the encountered pathologies. Therefore, in order to obtain propulsion in the GI tract, locomotion effectiveness, adaptability and dexterity are required. A biomechanical integrative approach has been followed, based on the investigation of biological legged locomotion models, with the aim to derive design rules for a legged artificial system. Because of the locomotion parameters which are critical for obtaining an effective locomotion are a lot and they are often difficult to be modelled and simulated, an experimental set-up has been developed in order to accomplish the problem analysis before designing the final endoscopic wireless capsule. An hexapod device with a sprawled insect-like posture has been developed. The device is provided with six superelastic legs, which are actuated by push-pull cables moved by traditional DC servomotors. Preliminary tests on porcine bowel and on latex GI simulators have been performed on a dedicated and sensorized design of a future test-bench, thus allowing to derive important guidelines for the wireless capsule development and for implementing the best gait