Arduino-based PID Control of Humidity in Closed Space by Pulse Width Modulation of AC Voltage

Abstract

My previous work explored a method for constant temperature proportional-integral-derivative (PID) control in a closed space using an Arduino. Similarly, this paper proposes a method of PID control to keep the humidity constant in a closed space using Arduino. PID control by a pulse width modulation (PWM) signal with Arduino is used to keep the humidity constant due to the heat generated by an incandescent light bulb to which an AC voltage of 100 (V) is applied. Here, the humidity is measured using the temperature/humidity sensor DHT11. Specifically, the target value of humidity is set to 30 (%), and the experimental results of P, PD, PI, and PID controls are compared from the points of quick response and stationary performance. As an evaluation of stationary performance, the mean-square value of 1,000 data of the deviation (target value – measured humidity) is calculated, and the PID control is found to be the preferred control.