Designing a Motion Control System for Motorized Robot Arm

Title Designing a Motion Control System for Motorized Robot Arm
Authors Saqibur Rahman, Md. Reaz Ahammed, Fatama Hoque Mohona
Semester Fall, 2015

Robot ArmOur project is focused on designing a robot arm and controlling it via a suitable controller. We have used an HC-05 Bluetooth module with an Arduino Mega microcontroller to control the arm. The arm’s chassis is made out of acrylic sheet and has three metal gear servo motors and one unipolar stepper motor. The arm has two degrees of freedom: Pitch and Yaw. We have used Arduino RC application from Android Play store as a means of sending control commands to the Bluetooth controller. The arm is capable of moving 360o about the Z axis. In our project report, we have calculated the forces that work while the arm is in motion. The arm can carry a net load of 500 grams. We have also found out the mathematical model and open and closed loop transfer functions of the arm. We have run simulations in MATLAB for step response, root locus, pole zero plot and bode plot.

During the implementation part, we faced some difficulty programming the arm as we are fairly new with programming the Arduino. However, we overcame the problem after seeking help of friends and faculties from our department. There is one glitch in our project. The primary servo motor responsible for pulling the arm up does not go all the way up. This is because the weight of the arm is actually a bit more than that calculated theoretically. Two servos working in parallel would solve the problem but it was too late to redesign the entire chassis. Our arm works fine and is able to lift weights and place it accurately to another position with the help of the stepper motor. A picture of our completed robot arm is given on the next page.