Experiments on the Edge of Chaos of a Planar Closed Chain Underactuated Mechanism

摘要

Experiment investigation of planar five-bar underactuated mechanism is carried out. The focus is on chaotic motion and the edge of chaos, at which the motion of the mechanism changes from period to chaos. The angular velocity of active joint is taken as the controlling parameter, i.e. the input angular velocity. Eighty seven values of input angular velocity ranging from 0.57 to 49.78 rpm are set to experiments. The displacements of the slider connected with frame are measured. Based on the data acquired, chaotic motion is identified by means of phase portrait, Poincare mapping and Lyapunov exponent. The results of experiments show that the motion of mechanism undergoes from periodic motion to chaotic motion with the increasing of the input angular velocity. The edge of chaos is not a value of input angular velocity, but a range of input angular velocities. And at the edge of chaos, the periodic motion coexists with chaotic motion, and the motion of the mechanism alternates between the two states of motion.