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9.5 Conclusion 159

5. Using acceleration feedback: Acceleration feedback improves the performance
of all types of servo motors. The improvement is greater for hydraulic and AC
motors, but the difference in dynamic performance between all types of motors
reduces. In this case, the saturated performance of servo motors influence the
final decision more than the dynamic characteristic, so that the maximum avail-
able torque is important. It should be noted when using acceleration feedback
that the velocity feedback must be differentiated. Therefore, high quality veloc-
ity transducer must be used so that there is not much noise in the acceleration
feedback. A filter must be used to minimize the noise in the acceleration feed-
back. Some manufacturers provide a current feedback instead of acceleration
feedback.
If, for a particular application, a number of servo motors satisfy for the dynamic
requirements, the final decision depends on capital cost, reliability, and availability.
In this chapter, a selection procedure has been outlined and it is only a guidance
for selection. The reader is encouraged to study the dynamic behavior by solving
the mathematical model of different complexities to ensure that the right motor has
been selected.