Chaos Suppression Of An Underactuated Manipulator: Experimental Results

In this paper, a phase space reconstruction technique and the estimation of the maximum Lyapunov exponent allow to show that the long-term dynamics of a two-link, planar, underactuated manipulator may be chaotic. The problem of stabilizing unstable periodic orbits (UPO's) embedded in the system chaotic set (attractor) is considered. A time delay feedback control strategy for chaos is used to stabilize an UPO of the system. The main advantage of the proposed control method is its simple structure. This structure can be implemented in almost any physical system, even if information about some system variables is not available. Besides, system stabilization is achieved with small control efforts, because the control scheme makes use of the inherent properties of the system chaotic behavior. Experimental results showing the closed loop system performance around a period one UPO are shown.