Forward and backward motion control of a vibro-impact capsule system

Abstract

A capsule system driven by a harmonic force applied to its inner mass is considered in this study. Four various friction models are employed to describe motion of the capsule in different environments taking into account Coulomb friction, viscous damping, Stribeck effect, pre-sliding, and frictional memory. The non-linear dynamics analysis has been conducted to identify the optimal amplitude and frequency of the applied force in order to achieve the motion in the required direction and to maximize its speed. In addition, a position feedback control method suitable for dealing with chaos control and coexisting attractors is applied for enhancing the desirable forward and backward capsule motion.The evolution of basins of attraction under control gain variation is presented and it isshown that the basin of the desired attractors could be significantly enlarged by slight adjustment of the control gain improving the probability of reaching such an attractor.

Experimental verification of the vibro-impact capsule model

“…The bifurcation studies presented in this paper are carried out for a range of system parameters where physical arrangement is feasible. For example, varying the frequency of external excitation in the range of ω ∈ (0, 0.4) allows to validate the results presented in [3] but also to demonstrate some new finding. Also, an ideal secondary linear spring assumption used in previous studies in [1][2][3] is discussed in this paper and the implications for the presented experimental set up are revealed.…”

“…This paper presents a verification on a novel experimental rig of the vibro-impact capsule model, which has been studied numerically by Liu et al in [1][2][3]. The capsule is excited by the harmonic force applied to the inner mass and the proposed mathematical model interprets the interactions between the inner mass and the capsule by assuming them as a whole possessing intrinsic stiffness and damping.…”

“…[4]). On the other hand, when the force is applied to the inner mass, the interaction between the capsule and the inner mass needs to be described, and Liu et al [1][2][3] used intrinsic stiffness and damping of the internal connection to consider overall dynamics of the capsule under applied harmonic force. In order to verify this modelling approach, a novel experimental rig was designed and manufactured, and an experimental study of the vibro-impact capsule system is presented in this paper.…”

“…the stiffness ratio, and the frequency and the amplitude of the excitation. In [2], the dynamic analysis of the capsule system in various friction environments was performed, while in [3] forward and backward motion control of the system was investigated using a position feedback controller. This paper provides an experimental verification of the vibroimpact capsule model proposed in [1].…”

Controlling multistability in a vibro-impact capsule system

“…On the other hand, coexistence of several stable solutions offers great flexibility in the performance of engineering systems, because the system behavior can be changed without altering its major control parameters. For this reason, a significant amount of effort has been dedicated to the development of control strategies that allow judiciously switching between stable solutions in a multistable dynamical scenario; see, e.g., [1,5,6] and the references therein.…”