Multi-objective optimisation based on reliability analysis of a self-propelled capsule system

In order to promote the stability of a self-propelled capsule moving in digestive tract, the target moving speed, the minimal impact force and the minimal energy consumption are considered as the optimisation objectives simultaneously. The uncertainty of small intestine environment is described by varying the external friction coefficient of capsule. Under such circumstances, NSGA-II, Monte Carlo, and Six-Sigma algorithms are combined to conduct the multi-objective optimisation of both the control and structure parameters based on reliability analysis. Compared with the passive capsules which can only move in one direction relying on small intestine peristalsis, the bi-directional motion can be fulfilled by the self-propelled capsule via adjusting its optimisation parameters. According to the obtained optimisation result, the forward motion of the capsule can achieve a large scale of moving speeds; however, it is difficult for the capsule moving backward with high speed. The reliabilities of both the energy consumption and the impact force can reach 100% via reliability optimisations; however, the reliability of the target moving speed of capsule is hard to be promoted up to 90%. Both the optimisation method and the optimisation result introduced in the paper are expected to be benefit to the improvement of the self-propelled capsule system and its application in wireless endoscope.

Automated summary

This paper focuses on the stability of a self-propelled capsule moving in the digestive tract and proposes a multi-objective optimization method. By adjusting the optimization parameters, the capsule achieves bi-directional motion and improves the reliability of energy consumption and impact force through reliability optimization. The research findings are of great significance for improving the self-propelled capsule system and its application in wireless endoscopy.