LINEAR SERVO THEORY 



619 



There are many other specific devices used to convert from mechanical 

 to electrical quantities. Most are equivalent to the potentiometer or syn- 

 chro circuit, one such being a lobing radar antenna, which delivers a voltage 

 proportional to an angular difference. A different, less widely used device 

 is the accelerometer, a generator which delivers an output voltage propor- 

 tional to the angular acceleration of its shaft. Its characteristic is that of a 

 transfer inductance or inertia. 



T=Hte 



de 



(0) 



(b) 



Fig. 2 — Motor as a transfer device, (a) Motor and load, (b) Equivalent mechanical mesh. 



POTENTIOMETER 



~- e^Ste 



SYNCHRO CIRCUIT 



n 



62 



e= s.' e,-e- 



TACHOMETER 



e e = R* e 



Fig. 3 — Alechanical-electrical transfer devices. 



2.2 Frequency Analysis 



A brief review of the basic concepts of periodic analysis will be presented. 

 It is assumed that the driving force applied to a network may be analyzed 

 in terms of a series of sinusoidal components of various amplitudes, fre- 

 quencies, and phases. The network response to each sinusoidal component 

 is then evaluated, and the over-all result obtained by a summation of all 

 such elementary responses. This is tlie formal procedure. Actually 



