How to Build a Speed Sensor using Arduino?

The speed sensor system centers around an Arduino UNO R3 development board connected to two infrared (IR) sensors placed a fixed, known distance apart. Each IR sensor emits infrared light and detects its reflection; when a moving object passes in front of the first sensor, it interrupts the beam and triggers a state change detected by the Arduino. The microcontroller immediately starts an internal timer. As the object continues moving and triggers the second IR sensor, the timer stops. Using the measured time interval elapsed between the two triggers and the known physical distance between the sensors, the Arduino calculates the speed of the object using standard kinematic equations. This computed velocity is then transmitted via the I2C communication protocol to a 16x2 LCD display, which renders the real-time speed output for the user. Power is supplied to the entire circuit via a 12V power adaptor connected through the board's DC barrel jack, ensuring stable operation for both the logic microcontroller and the peripheral display and sensor modules wired across the breadboard using connecting wires.