www.tjprc.org SCOPUS Indexed Journal editor@tjprc.org MODELLING OF A VIBRATION-DRIVEN MODULE FOR CAPSULE LOCOMOTION SYSTEMS KHAC-TUAN NGUYEN 1 , VAN-DU NGUYEN 2 , KY-THANH HO 3 & NGOC-TUAN LA 4 1,2,3 Research Scholar, Thai Nguyen University of Technology, Thai Nguyen University, Vietnam 4 Research Scholar, Vinh University of Technology Education, Vietnam ABSTRACT This paper presents a model for locomotion systems based on the combination of vibration and impact of an oscillating mass with two-side elastic constraints. The proposed system is excited by a periodic half-sine waveform force. A mathematical model was developed to form a basis of the design and to choose proper operational parameters. The numerical solution showed that the system was able to move backward and forward as desired by simply reversing the excitation force. Several advantages of the new model, compared to the recent platform excited by square force were highlighted. Dynamics response of the new model was also analyzed by applying bifurcation technique. In addition, the new model was proved to able to move in desired direction under both anisotropic and isotropic friction conditions. This model is promising to apply in capsule robots, where the whole system must be encapsulated in a smooth form and should be able to move in different friction conditions. KEYWORDS: Self-Propulsion; Vibration-Driven Locomotion; Capsuled Robot; Isotropic Friction & Anisotropic Friction Received: Apr 21, 2020; Accepted: May 12, 2020; Published: May 29, 2020; Paper Id.: IJMPERDJUN202075 INTRODUCTION There have been growing demands and remarkable development of mobile systems witnessed in recent years, especially in the field of locomotion robots. The systems have extensive prospective applications, ranged from large-size systems (Cazalilla, Vallés, Valera, Mata, & Díaz-Rodríguez, 2016) working in remote and hostile environments, disaster rescues, pipeline inspection…(Yaguchi, Kamata, & Sugawara, 2016), (Shukla & Karki, 2016) to miniature robots for medical assistance (Mohamed, Elgamal, & Elsharkawy, 2018). Conventional mobile systems usually consist of external actuation components, such as wheels, legs or paddles, which would have restrictions in mechanical complexity, physical size, failure of moving parts, and affecting hazard to working environment. Consequently, the design of new locomotion systems without external driving mechanism is required so that it can be easily encapsulated in a smooth form. There have been two design principles of such encapsulated locomotion systems, as briefly summarized below. The two-mass system, initially proposed by Chernousko in 2002 (Chernous'ko, 2002), provides a promising propulsion mechanism for expected limbless locomotion platforms. In this system, the rectilinear motion of the primary mass (the system body) can be achieved by using a periodically driven internal mass interacting with the main body in the presence of dry friction. The internal mass must be controlled to move inside with special multi-phase accelerations (see (Huda & Yu, 2015), (Nikolay Bolotnik, 2015), (Su, Zhang, Tan, & Li, 2009), (Li, Furuta, &Chernousko, 2006) for example). The locomotion can be generated when the inertial force, caused by acceleration changes, exceeds the friction threshold between the body and the surrounding environment. The major Original Article International Journal of Mechanical and Production Engineering Research and Development (IJMPERD) ISSN (P): 2249–6890; ISSN (E): 2249–8001 Vol. 10, Issue 3, Jun 2020, 837–850 © TJPR Pvt. Ltd.