Fabrication and Control of 4-DOF, Autonomous Robotic Arm using Low Cost AVR Controller

A.W. Butt, J. Iqbal, S. Bano, N. Hassan, and R. Ilyas (Pakistan)


Manipulator, inverse kinematics, Digital image processing, closed loop controls and low cost.


This paper summarizes the design, fabrication and control of a four degree of freedom autonomous robotic arm using digital image processing. Control of the robotic arm has been achieved successfully using four servo motors, each of which incorporates high resolution quadrature encoders. The robotic arm is equipped with a pair of audio video cameras. These cameras transmit real time video to a Pentium based processor. The image processing module searches the video stream for predefined templates and calculates the coordinates of the object to grasp and transmits them serially to an array of microcontrollers. The microcontrollers implement inverse kinematics algorithms and implement position control on the motors. The motors are actuated using the internal PWM channels of the microcontroller and MOSFET based power amplifiers. The robotic arm also has the provision of being controlled without the cameras relying on user input for the starting and terminating coordinates. These coordinates are fed to the controller directly using a keypad and LCD module by-passing the Pentium processor. Thus even without a vision system the robotic arm may be defined as being autonomous. The end effector is a two finger gripper. The robotic arm has a load bearing capacity of 500gms and a maximum workspace of 650mm along the horizontal plane.

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