Research On Force Sensing And Compliance Control Of Colonoscopy Robot

Due to the aggravation of environmental pollution and constant changes in diet, colorectal cancer has nowadays become the third most common cancer among male, and the second among female. In China in particular, the incidence of colorectal cancer increases with an annual growth rate of 4%, twice the world level. Conventional colonoscopy adopted during the checking process, lacking in its bending capacity, easily causes discomfort and heavy pain on the part of the patients. It even leads to intestinal perforation in some extreme cases. Eager to find a solution, more and more scholars are now trying to apply robot technology into colorectal endoscopy.The relative floating property of human intestinal predetermines its unfixed position and shape, therefore requiring a much safer and more reliable process of inspection. To achieve that improvement of safety, this study looks into compliance control method and control system of the colonoscopy robot, which is based on a force sensing system. The force sensing system can keep a real-time control of the force between the robot and intestinal. The proposed compliance control method will make sure that such a force be kept within the safety threshold, thus making colonoscopy a much safer process. The study is divided into three parts:1. A design of the force sensing system and the sensor parameter identification. This study first makes a modeling and simulation analysis of surface deformation of the colonoscopy robot. Based on the results of that analysis, the pressure sensor and signaling circuit are designed. A further experiment is done on identifying the sensor parameter.2. A compliance control of the colonoscopy robot based on force sensing. First, the active control method relying on human guidance is proposed after analyzing the relationship of the joint motion. After that, a compliance control algorithm was raised after analyzing the biomechanics of the intestinal and coupling relationship between the joints of the robot.3. The construction of a control system and an experimental study. The control system consists of three major parts: the bending control system, the forwarding control system and the force sensing system. The hardware and software are designed and debugged separately. Based on this, the bending and the intestinal model experiments are conducted to verify the feasibility of the compliance control algorithm.The experimental results show that the design of the force sensing system can help provide a real-time perception of the force exerted when the colonoscopy robot bents over, thus meeting the requirement of both controlling and buffering the forces on human body. In addition, the intestinal model experiment proves that the proposed compliance control method helps improve the robot’s ability to sense the force between the robot and intestinal, keeping the force within the safety threshold and therefore ensuring a more secure process of colonoscopy.