CHAPTER FIVE
PRACTICAL CONSIDERATIONS
In this chapter practical aspects dealing with implementing the control algorithm for the nonlinear servomechanism problem are treated.
First discussed is a modification of the already proposed control algorithm which is specifically tailored for tracking and disturbance rejection with respect to a nominal trajectory. The modified design is based on deviations from the nominal trajectory and since these deviations are generally small, the demand on the stabilizing capabilities of the controller is minimized. Another benefit of the design is that
tracking of a wide class of reference signals is made possible by supplementing the closed-loop feedback with open-loop control inputs.
The final section of this chapter deals with discrete-time
techniques so that the control algorithm can be implemented using a digital computer.
Controller Based on the Nominal Trajectories
In this section we develop a controller for the servomechanism problem which operates relative to nominal reference and disturbance signals. The design presented here employs not only feedback control but also feedforward control to achieve the desired trajectory. Although feedforward control is introduced, the control scheme is
formulated in essentially the same way as was done in previous treatment of the nonlinear servomechanism problem.