<b>Design and Fabrication of Sentry Gun based on Mechatronics System</b> The project is concerned with the design and fabrication of sentry gun using Mechatronics System. It is a gun which is automatically aims and fires at the targets that are detected by a camera. The sentry gun uses a camera based weapon system to detect track a target and hardware to aim and fire at the target. As per today’s military status, this system is not readily used by the military even though it has a greater potential. The system would replace the active function of an armed guard while keeping a human life out of harm. Overall, this system has a lot of potential in the modern day military strategy and would help soldiers in the field of operation. The main components of the project are Arduino, Servo motor, Camera, Paintball gun. An Arduino is a microcontroller, which can be interfaced with the computer and can control the servo motor. Three servo motors are used to control the movement of the gun and base, such as “Pan” control servo motor, “Tilt” control servo motor and “Trigger” control servo motor. The Pan Servo motor controls the side to side movement of the gun. The Tilt servo motor controls the up down movement of the gun and the remaining servo motor is used to squeeze the trigger of the gun. The camera will scan the object depending upon the Arduino code and the feedback is sent back to the Arduino controller. The gun has the ability to scan its field of view using a camera and can fire automatically at the target. The camera image is processed in the Arduino controller and the target is fixed with the help of servo motor and the target is aimed and fired. This project can be used as a defensive gun weapon in military battlefields and it can also be used for the local security purpose, businesses or as a house guard. The benefit of this sentry gun gives more accuracy, safety, less cost, nil risk for the guard and has a diverse scope in future battle fields. sentry gun, automation, image processing, arduino, mechatronics system 499-505 Issue-2 Volume-2 Pradeep S | Anand V | Harish Kumar R | Ragu R