The objective of this lab is to design a fuzzy logic motor controller. The desired speed is received from a user interface (either a keypad or the SCI). You should use a variable-speed DC motor, playing careful attention to the voltage and current specifications of the motor. Attach onto the motor shaft a circular disk, and paint contrast lines in a circular pattern around the disk. Mount a reflectance optical sensor, such as the QRB1113 or QRB1134, pointing toward the disk, and interface it so that there is a digital square wave with a frequency related to the speed of the shaft. Build the state estimator that measures both shaft speed and acceleration in real time. Measure the current required to spin the motor at full speed. Design a PWM actuator so the software can control the delivered power to the motor. It is OK if the actuator precision is greater than the 8-bit fuzzy logic numbers. Make sure the snubber diode can handle the back EMF generated when the motor is switched off. Use the PWM in open-loop fashion and the state estimator to generate a DC response curve like that shown in Figure 13.24. Furthermore, you should measure the time-constant of the physical plant (time to 0.69 of final response after a step change in input). Design and implement an initial fuzzy logic controller and add debugging instruments to measure fuzzy variables in real time. Run through an experimental fine-tuning, optimizing the fuzzy parameters in order to minimize both controller error and response time.
Figure 13.24
