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Download 1.59 - Department of Computer and Electronics Engineering
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Department of Electronics Engineering – UoP Control System: Sample problems Engr. Cezar N. Velasco Jr. 1. A variable resistor, called a potentiomer, the resistance is varied by moving a wiper arm control solutions along a fixed resistance. The resistance from A to C is fixed, but the resistance from B to C varies with the position of the wiper arm. If it takes 10 turns to move the wiper arm from A to C, draw a block diagram of the potentiometer showing the input variable, the output variable, and (inside the block) the gain, which is a constant and is the amount by which the input is multiplied to obtain the output. Answer: 5 turns yields 50 V. Therefore K = 50 𝑉𝑜𝑙𝑡𝑠 5 𝑥 2𝑝𝑖 𝑟𝑎𝑑 = 1.59 K- Constant 2. A temperature control system operates by sensing the difference between the thermostat setting and the actual temperature and then opening a fuel valve an amount proportional to this difference. Draw a functional closed-loop block diagram and identifying the input and output transducers, the controller, and the plant. Further, identify the input and output signals of all subsystems. Desired Temp Temp diff + Voltage Diff Actual Temp 3 Thermostat - Fuel flow Amplifier and valves Heater 3. An aircraft's attitude varies in roll, pitch, and yaw as defined in Figure. Draw a functional block diagram for a closedloop system that stabilizes the roll as follows: The system measures the actual roll angle with a gyro and compares the actual roll angle with the desired roll angle. The ailerons respond to the roll angle error by undergoing an angular deflection. The aircraft responds to this angular deflection, producing a roll angle rate. Identify the input and output transducers, the controller, and the plant. Further, identify the nature of each signal. Department of Electronics Engineering – UoP Control System: Sample problems Engr. Cezar N. Velasco Jr. Desired Roll angle input voltage Pilot controls + - Error signal Position Aileron Position Control Roll rate Aircraft dynamics Roll angle Integrate Gyro voltage Gyro 4. Assignment: Many processes operate on rolled material that moves from a supply reel to a take-up reel. Typically, these systems, called winders, control the material so that it travels at a constant velocity. Besides velocity, complex winders also control tension, compensate for roll inertia while accelerating or decelerating, and regulate acceleration due to sudden changes. A winder is shown in Figure 1.3. The force transducer measures tension; the winder pulls against the nip rolls, which provide an opposing force; and the bridle provides slip. In order to compensate for changes in speed, the material is looped around a dancer. The loop prevents rapid changes from causing excessive slack or damaging the material. If the dancer position is sensed by a potentiometer or other device, speed variations due to buildup on the take-up reel or other causes can be controlled by comparing the potentiometer voltage to the commanded speed. The system then corrects the speed and resets the dancer to the desired position. Draw a functional block diagram for the speed control system, showing each component and signal.
