Disturbance reduction in servo systems

Disturbance accommodation control (DAC) is a method of control which allows for the reduction of the adverse effects of the external disturbances acting on the linear and some nonlinear systems (and in some cases complete absorption of the disturbance effects). For this control scheme to work, the disturbances must be of known waveform type, such as a step function, ramp function, sinusoidal function, etc. The basic idea of DAC is to model the disturbance, augment its state equations to the system state equations, and then reconstruct the states of this augmented system for use in a controller that minimizes the effects of the disturbance. Disturbance accommodation control is applied to reduce the adverse effects of step, ramp, and sinusoidal disturbances acting on a servo system.