Perform System Analysis of Antenna Azimuth Position Control Figure 1 shows the antenna A schematic and functional block azimuth control system. The purpose of this system is to have the azimuth angle 0.(t), follow the input angle of the potentiometer, 8(t). The potentiometer converts the angular displacement into a voltage. Similarly, the output angular displacement is converted to a voltage by the potentiometer in the feedback path. The signal and power amplifier boost the difference between the input and output voltages. This amplified actuating signal drives the plant.
The Correct Answer and Explanation is:
System Analysis of Antenna Azimuth Position Control System
The antenna azimuth position control system is a classic example of a closed-loop control system designed to regulate the angular position (azimuth) of an antenna. Its purpose is to make the actual azimuth angle of the antenna, denoted by θo(t)\theta_o(t), follow the desired input angle θi(t)\theta_i(t), typically set by an operator through a potentiometer.
Functional Components:
- Input Potentiometer:
- Converts the desired azimuth angle θi(t)\theta_i(t) into a corresponding voltage signal.
- This voltage serves as the reference input to the control system.
- Feedback Potentiometer:
- Measures the actual antenna angle θo(t)\theta_o(t) and converts it into a voltage signal.
- This voltage represents the system’s output for feedback comparison.
- Comparator (Error Detector):
- Computes the error signal: e(t)=Vin(t)−Vout(t)e(t) = V_{\text{in}}(t) – V_{\text{out}}(t), where voltages represent angular displacements.
- The error signal determines how far the system is from the desired angle.
- Signal and Power Amplifier:
- Amplifies the error signal to generate a strong control input.
- This signal is sufficient to drive the plant (motor or actuator).
- Plant (Actuator and Antenna):
- The physical system that rotates the antenna to the desired angle.
- Accepts the control input and changes the output angle θo(t)\theta_o(t).
System Characteristics:
- Type: Negative feedback control system.
- Goal: Minimize the error e(t)e(t) to achieve θo(t)≈θi(t)\theta_o(t) \approx \theta_i(t).
- Stability: Can be assessed by analyzing the closed-loop transfer function.
- Performance Metrics: Include steady-state error, rise time, overshoot, and settling time.
Explanation
The antenna azimuth position control system functions as a closed-loop electromechanical control system where the primary objective is for the output azimuth angle θo(t)\theta_o(t) to track the input angle θi(t)\theta_i(t) accurately over time. This tracking is essential in applications such as radar, satellite communication, and military systems, where precise directional control is critical.
At the heart of the system is a feedback loop incorporating potentiometers to convert angular displacement into corresponding voltage signals. The input potentiometer transforms the desired antenna direction into a voltage signal. Simultaneously, the actual antenna position is monitored via a second potentiometer in the feedback path, which also outputs a voltage. These voltages are compared to produce an error signal.
The error signal, representing the difference between the desired and actual positions, is sent to a signal and power amplifier. This stage boosts the error signal’s magnitude, ensuring it is strong enough to drive the actuator. The actuator (plant) then physically rotates the antenna in response to the amplified signal.
The feedback mechanism continuously updates the system about the antenna’s current position, creating a dynamic response that adjusts the output to minimize the error. Over time, the system settles when the error becomes negligible, indicating that the output angle closely matches the input.
This feedback control setup ensures system accuracy, stability, and responsiveness. By analyzing the block diagram and modeling the system mathematically (e.g., using transfer functions and Laplace transforms), control engineers can further design and tune the system for desired performance such as fast response, minimal overshoot, and reduced steady-state error.
