In this section the software used in the design is explained. The distance of the ball is measured by the ultrasonic range sensor HCSR-04. Athree-point median filter is used to eliminate spikes in the measurements. A set point altitude is input to the software and the difference between the set point and current altitude is the error, which is the input of the PID controller. The output of the PID controller is the current command, which is sent to the blower driver so as to control the air flow speed and hence adjust the ball’s altitude. The current control driving the blower is shown in Figure 3.The reason for the current control circuit design is to be able to achieve a quick response and to operate in the narrow range required for the setup at hand. The current control circuit utilizes a TIP 120 Darlington transistor since the Arduino itself cannot provide the high current required by the blower motor. Fig. 3. Arduino circuit connections Fig. 6.Tuned PID parameters in MATLAB/Simulink Fig. 5. PID controller system in MATLAB/Simulink Conclusions and Future Works In this paper an experimental setup was developed to keep a ball in a pipe at a desired altitude. A PID controller was designed and tuned using MATLAB/Simulink with small overshoot and fast settling time. The controller was implemented using an Arduino Uno board to control the air flow
