Friction and backlash induced limit cycles in mechanical control systems

In this paper the oscillatory behaviour of position control systems is analysed. It is considered that in the controlled mechanical system both friction and backlash type nonlinearities are present and the controller contains integral term. For such systems a method is proposed to determine a limit cycle condition between the mechanical system parameters and controller parameters. A simulation model was developed to examine the chaotic nature of the control system response. Some specific chaos measures of the response (fractal dimension and Lyapunov exponent) are determined.