Design and Construction of a Microcontroller-Based Five Degree of Freedom Robotic Arm Using Servo Motors

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Ndwiga, Nicholus Kariuki
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Kenyatta University
Integration of robotic arms into working tasks has currently increased magnificently in performing the very repetitive, dangerous or difficult tasks. Typically, a robotic arm is a mechanical arm that is programmable to mimic the behavior of a human arm in terms of how it functions. Computers and microcontrollers have widely been used in the control of robotic arms with the help of sensors, levers, buttons, wireless devices, just to mention but a few. More advanced technology has lately revolutionized their control, ranging from the haptic technology using accelerometers to human-brain control through noninvasive technology. One of the areas robotic arms are used in our day to day life is in land movers like in excavators, bulldozers, backhoes, front loaders and trenching machines. The available arms for these devices need personnel throughout their operations to control and manipulate their movements using gears, levers, pistons, pedals and sometimes buttons. There is a great need to complement their movement so that they can autonomously operate once they are powered. This research focused on the design, implementation and control of a robotic arm with five degree of freedom (DOF) using servo motors. It was designed to entirely operate by itself in a repetitive routine. A control circuit based on a PIC18F4550 microcontroller interfaced with a servo motor was built and a suitable software for the control of the rotation of motor developed. The control circuit was used to send appropriate Pulse Width Modulation (PWM) signals to different motors to produce the desired rotation. In this study five servo motors were employed to realize the robotic arm. Three servos were utilized to control the body motion including base, shoulder, and elbow and two servos were used for the motion of end effector, the wrist and the gripper. The software for the control of rotation of the motors was done using C programming language. The codes were developed and debugged using the mikroC PRO for PIC Integrated Development Environment (IDE). PICkit™3 in-circuit programming module was used to upload the program to the microcontroller through PICkit™3 programmer software. The materials were assembled and joined to construct the robotic arm which was tested in the University laboratory to demonstrate repetitive picking, lifting and dropping of objects of specific weight from one place to another without the influence of the operator.
A Thesis Submitted in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science (Electronics and Instrumentation) in the School of Pure and Applied Sciences of Kenyatta University.