Consider the case of Antenna Azimuth position control system. The Schematic and functional block diagrams are shown in Fig. 3 and Fig. 4 respectively. The purpose of the system is to have azimuth angle output of the system θ(t), follow the input angle of the potentiometer, θi(t). The input command is an angular displacement. The potentiometer converts the angular displacement into a voltage. The signal and power amplifiers boost the difference between the input and output voltages. This amplified actuating signal drives the plant.
Antenna
Desired
θ0(t) Azimuth angle output
θi(t) azimuth angle input
Differential amplifier and power amplifier
Motor
Potentiometer
Figure 3: Schematic of Antenna Azimuth position control system
Input
Power Motor, load Preamplifier amplifier and gears Vp(s) = 100
Ea(s) = 0.2083/(s(s + 1.71))
potentiometer
θ(s)
1/T
1
Output potentiometer
Figure 4: Functional block diagram
a) For the antenna azimuth position control system, Identify the system type and the steady state error in terms of gain K, for step, ramp, and parabola inputs. [5 Marks]
b) Sketch the root locus of the antenna azimuth position control system as K varies from 0 to ∞ (Hint: find all the necessary data). [7 Marks]
c) Using Routh's stability criterion, Identify the range of preamplifier gain K for stability [3 Marks]