Feedback Control of a SISO System

The figure below shows symbolic representation of a single input single output (SISO) vibration system. Many closed loop control system could be modelled in this form. A typical application of such control system is in the field of engine vibration control. The figure below illustrates such a system. The disturbance force generated at the engine is transmitted to the vehicle through engine mounts. The vibration is sensed by a single accelerometer ( single output), passed to the controller which produces a negative of the output signal (ref, is usually zero in vibration problem). The control signal is amplified through a power amplifier and fed to the actuator. The actuator force is of such a magnitude and direction that it cancels the effect of vibration.

Figure 23.1: Closed loop control of a SISO system

The input-output relationship of a dynamic system is represented as a black-box consisting of frequency domain description of the system transfer function.