This is roughly the uncertainty in the servo system design of this study. Hence, system performance is marginal and it would take a more detailed study to determine whether the specification can be met. It can also be seen that with position feedback from the load, ringing may not be a problem. For the configuration where the position feedback is taken from the motor, the step responses shown in Figure 9 are obtained. The system is now faster than for Figure 8 but heavy ringing takes place due to the fact that the load movement is outside the servo loop.
Step responses for a system with position feedback from the motor.
The curves above show the movement of the load. Intense ringing occurs. In practice, the system will have a performance somewhere between that of Figure 8 and Figure 9. Hence ringing may be a problem and it is of interest to discuss methods of suppressing such effects. Two approaches can be identified.