Chaos in a Pendulum with Forced Horizontal Support Motion:
a Tutorial
R. VAN DOOREN
Department of Mechanical Engineering, Free University of Brussels, Pleinlaan 2, B-1050 Brussels, Belgium
Abstract-This contribution presents a tutorial on chaos in forced pendulum motion. A pendulum
system with its support forced along a horizontal line is considered. The bifurcation diagram in
function of the amplitude of the forced periodic motion shows several period doubling subharmonic
cascades, chaotic motions and windows of periodic motions. It is illustrated that the cascades are
governed by Feigenbaum’s number from Universality Theory. The chaotic attractors are investigated
for their characteristics such as its evolution in the phase plane, the computation of the Liapounov
exponents, the Liapounov dimension, the power spectrum and the winding number