The possibility of eliminating chaos in a dynamical system or of decreasing the leading Liapunov exponent by applying a weak periodic external forcing to the system is demonstrated through the example of a periodically driven pendulum. The applications of the external forcing also results in other striking changes in the dynamics such as a stabilization of narrow subharmonic steps and the achievement of very low winding numbers.

• Received 12 June 1990

DOI:https://doi.org/10.1103/PhysRevLett.66.2545