Question

Produce a brief description to the sources of non linearity in control systems ((mentioning its effect on the system response))

Answer 1

Sources of non-linearity in control system
A non-linear system is defined as a system whose output is not proportional to the variation of the input signal. In non-linear system, there exists at least one nonlinear component. In linear control system, we assume that for a small range of operation the linear analysis is valid. However, when the operating range is large, the linear controller is poorly performed. Hence, non-linear controller would be required.
Now, we need to know what the sources of nonlinearity are. In most of the control application, nonlinearity is mainly arisen due to the nonlinear forces associated with the system’s performance. In robotic operation, nonlinear forces are mainly coming from the unwanted frictional forces such as Coriolis and centripetal forces. Now, when the speed of operation increases, the performance of the controller degrades. The hard nonlinearities such as Coulomb friction, saturation, dead-zones, backlash, hysteresis etc. are the major sources of nonlinearities.
The effects of nonlinearities cause undesirable behavior of the system responses such as unstability in the limit cycles, undesired system behavior, slow time variation of the parameters etc.