LabVIEW Based Closed Loop DC Motor Speed Control and Performance Analysis Under Variable Load Condition

This paper describes a low-cost closed-loop speed controller for a 12 V brushed DC motor, written so that the build can be repeated. An ESP32 times the pulses of an optical slot sensor on an 8-slot disc, filters the speed and sends it over USB serial every 20 ms. A LabVIEW VI runs the PID controller and returns a PWM command (0–255) that the ESP32 applies to an L298N driver. All hardware, firmware, VI and test settings are listed, together with the tuning procedure. Mechanical load is applied by hand with a friction pad. We analyse the delay in the loop and show, from the firmware parameters, that the speed filter (about 47 ms of mean lag) dominates the estimated 63 ms loop dead time, while USB-serial timing jitter is only a few milliseconds. In a demonstration run, the PID output stayed between 231 and 248 counts and the mean speed was within about 4 % of the setpoint, but the speed estimate was very noisy because of the hand-cut disc.