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Velocity Estimator for Quadrature Servo Signals

IP.com Disclosure Number: IPCOM000035326D
Original Publication Date: 1989-Jul-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 3 page(s) / 69K

Publishing Venue

IBM

Related People

Ell, TE: AUTHOR

Abstract

Fig. 1 (the block diagram) shows the basic parts for the velocity estimator. There are two integrators, five unity gain inverters, one inverting summer with a gain of ten, and eight analog switches. Fig. 2, the timing diagram, shows the three analog input signals needed to run the estimator. These signals are +Current, +Cosine, and +Sine. (Image Omitted) The output of the estimator is the analog signal +Estimated Velocity. The remaining signals are internally generated logic signals which control analog switches. The Circuit Diagram shows the actual hardware used for the estimator. The module count stands at eight off the self parts. The passives required are two capacitors and the 33 resistors.

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Velocity Estimator for Quadrature Servo Signals

Fig. 1 (the block diagram) shows the basic parts for the velocity estimator. There are two integrators, five unity gain inverters, one inverting summer with a gain of ten, and eight analog switches. Fig. 2, the timing diagram, shows the three analog input signals needed to run the estimator. These signals are +Current, +Cosine, and +Sine.

(Image Omitted)

The output of the estimator is the analog signal +Estimated Velocity. The remaining signals are internally generated logic signals which control analog switches. The Circuit Diagram shows the actual hardware used for the estimator. The module count stands at eight off the self parts. The passives required are two capacitors and the 33 resistors.

The position signal is generated by selecting between four different waveforms. For example, between time t0 and t1, +Sine is selected through switch 4 with switches 1-3 open. From time t1 through t3, +Cosine is selected with switch 2 closed and switches 1 and 3-4 open. From t3 through t4, -Sine is selected through switch 3 and from t4 through t5, -Cosine is selected through switch 1.

All of the switches are controlled by two comparators. The relationships for the comparators are: comparator 1 if +Sin > +Cosine then output = 1 if +Sin < +Cosine then output = 0 comparator 2 if -Sin > +Cosine then output = 1 if -Sin < +Cosine then output = 0

It is important to note here that all of the switch settings depend on the present states of the two inputs and on no past values.

A very simple description of how the estimator works is as follows: the current signal is integrated once to obtain velocity and a second time to derive position. Looking at Fig. 2, it is apparent that +Estimated Velocity is produced th...