Modelling of a vibro-impact self-propelled capsule in the small intestine

Abstract

This paper studies the modelling of a vibroimpact self-propelled capsule system in the small intestinal tract. Our studies focus on understanding the dynamic characteristics of the capsule and its performance in terms of the average speed and energy efficiency under various system and control parameters, such as capsule's radius and length, and the frequency and magnitude of sinusoidal excitation. We find that the resistance from the small intestine will become larger once the capsule's size or its instantaneous velocity increases. From our extensive numerical calculations, it is suggested that increasing forcing magnitude or choosing forcing frequency greater than the natural frequency of the inner mass can benefit the average speed of the capsule, and the radius of the capsule should be slightly larger than the radius of the small intestine in order to generate a reasonable resistance for capsule progression. Finally, the locomotion of the capsule along an inclined intestinal tract is tested, and the best radius and forcing magnitude of the capsule are also determined.

Modelling of capsule–intestine contact for a self-propelled capsule robot via experimental and numerical investigation

“…To model the hoop pressure, a local coordinate system [19,25] is built in Fig. 4, with x and R(x) representing the axial and radial directions, respectively.…”

Scenarios in the experimental response of a vibro-impact single-degree-of-freedom system and numerical simulations

“…Impacts occur, for example, in the capsule systems used in clinic endoscopy to inspect the surface lining of the intestine in the human body. The dynamics of this system is the subject of several works, of both numerical and experimental nature [2][3][4][5][6]. In these studies the endoscopy capsule is modelled by a two-degree-offreedom system, consisting of rigid capsule and a movable internal mass, the latter driven by a harmonic force with one-sided or two-sided constraints.…”

The vibro-impact capsule system in millimetre scale: numerical optimisation and experimental verification

“…In [17], Gu and Deng studied the dynamical response of a vibro-impact capsule system with Hertzian contact and random environmental perturbation. On the other hand, a lot of studies have focused on the prototype development of the vibroimpact capsule system for some specific practical applications, such as pipeline inspection [18][19][20], gastrointestinal capsule endoscopy [21], and ground moling [22]. The present study in this paper is to report our recent progress on scaling down the prototype design of the vibro-impact capsule system to a standard dimension for gastrointestinal capsule endoscopy, which is 26 mm in length and 11 mm in diameter.…”

“…The merit of such a capsule is its simplicity in mechanical design and control which does not require any external driving accessories, while allowing independent movements in a complex environment. The study of this method was initiated from mathematical modelling [7,8,26,27], early proof-of-concept investigation [28], multistable dynamics control [15,29], to our recent capsule-intestine contact modelling [30], intestinal friction study [31] and mesoscale demonstration [32,33]. Since the mathematical model of the system belongs to the class of piecewise-smooth dynamical systems, for this type of systems, the state space can be divided into disjoint subregions [34].…”