A Novel Expanding Mechanism of Gastrointestinal Microrobot: Design, Analysis and Optimization

Abstract

In order to make the gastrointestinal microrobot (GMR) expand and anchor in the gastrointestinal tract reliably, a novel expanding mechanism of the GMR is proposed in this paper. The overlapping expanding arm is designed to be used to increase the variable diameter ratio (ratio of fully expanded diameter to fully folded diameter) to 3.3, which makes the robot more adaptable to the intestinal tract of different sections of the human body. The double-layer structure of the expanding arm increases the contact area with the intestine, reducing the risk of intestinal damage. The kinematics and mechanical model of the expanding arm are established, and the rigid velocity, rigid acceleration, and expanding force of the expanding arm are analyzed. The elastodynamics model of the expanding arm is established. Through the finite element analysis (FEA), the velocity, acceleration, and the value and distribution of the stress of the expanding arm under elastic deformation are obtained. Based on the elastodynamics analysis, the structure of the expanding arm is optimized. By the structure optimization, the thickness of the expanding mechanism is reduced by 0.4mm, the weight is reduced by 31%, and the stress distribution is more uniform. Through the mechanical test, the minimum expanding force of the expanding mechanism is 1.3 N and the maximum expanding force is 6.5 N. Finally, the robot is tested in the rigid pipeline and the isolated intestine to verify the reliability and safety of the expanding mechanism.

The Modelling, Analysis, and Experimental Validation of a Novel Micro-Robot for Diagnosis of Intestinal Diseases

“…In order to obtain a large variable diameter ratio, two-layer expanding legs are adopted. It should be noted that the three sets of expanding legs are not driven by three pairs of pinions, as is traditional way [ 23 , 24 ]. They are driven by the same pair of annular gears, rotating relatively, shown in Figure 4 c, which better ensures their synchronization.…”

A Dielectric Elastomer Actuator-Driven Vibro-Impact Crawling Robot

“…Verma et al [ 16 ] demonstrated a pneumatic soft robot based on a buckling pneumatic actuator that is capable of crawling in tubes with turns, inclines, and variable-diameters. Wang et al [ 17 ] proposed a novel expansion mechanism for a gastrointestinal microrobot by adopting a double-layer overlapping design. This mechanism has a diameter adjusting ratio of 3.3, which enables effective anchoring and flexible crawling of the robot.…”

Design and analysis of a wireless power transfer system for capsule robot using an optimised planar square spiral transmitting coil pair

“…3 Therefore, the gastrointestinal capsule robot (CR), which features controllable locomotion and radial expansion, has become the focus of current research. [5][6][7][8][9][10] Different from CE in passive motion, the active CR integrates miniature actuators, cameras and other power consumption units, and therefore, it can consume several hundred milliwatts. Thus, how to provide stable and efficient power has always been a bottleneck to be broken through.…”