Design of Robotic Arm Using Delay Based Operation of DC Geared Motors With a Microcontroller

Abstract

This paper provides the design of a simple robotic arm for pick and place operations as well as other material handling operations. The movements of the arm are anthropometric i.e. resembling the human arm with respect to degrees of freedom so as to provide a human touch in industrial and space operations. This system operates using controlled motion of DC geared motors along with a microcontroller based system (8051 or PIC based). Use of PWM (Pulse Width Modulation) can be used to control the RPM of DC geared motors. This system has the advantage of being simple and low cost with a varied flexibility of operation. A collective array of sensors viz. voice sensor, infrared light sensors, proximity sensors etc. can be incorporated to form a feedback induced closed loop system. Whereas for tasks of picking and placing at a fixed location from another location the system can be operational at open-loop. The material for the robotic arm can be polypropylene or acrylic or aluminium to reduce weight without compromising on the strength and lifting capacity of the robotic arm, such that the torque of the DC geared motors (actuators) at each joint are sufficient to lift the arm along with the weight at the end effector. Clutch and gear shifting mechanism can be used to increase the degrees of freedom per actuator. The driving circuit mainly consists of the microcontroller and H-bridge drivers using an 8-bit port to control 4 DC geared motors per port simultaneously or one at a time using delay commands. DC geared motors are quite cheaper than stepper motors and RC Servos thus reducing the total cost of the system drastically. Plus being light weight, DC geared motors reduce the total weight of the system. This paper will also throw light on the programming aspects for the microcontroller (8051 or PIC based) along with the compatible flash programmers and HEX code generators. This project will further explain on the approach followed in the mechanical design of the robotic arm (motion, work volume etc.) as well as the possible future applications of the robotic arm. Also the design of the robotic arm on CAD tools like Solidworks will be discussed in brief along with the modeling and simulation of the various links of the arm as well as the whole assembly of the system. With increasing popularity of Automation, robotic arms are the present and future of all industrial operations. Finally the paper concludes on the further improvements in design and technology.