抽象的

Design and Development of a 3 axes Pneumatic Robotic Arm

Biswas Palok, S. Anandan Shanmugam

Pneumatic robots are essential for material handling in chemical industries where electric or hydraulic robots are unsuitable due to fire hazard. A 3 axes (3 Degrees of Freedom) articulated pneumatic robotic arm was designed and assembled in this project along with its control system. Pneumatic rod less linear actuators were used as the main drive system for the robotic arm and were controlled by pneumatic 5/3-way proportional directional control valve. The design of the arm for this project implements crank mechanism to convert linear actuation displacement to angular displacement about the joint. Two control systems were designed for the robotic arm: Programmable Logic Controller (PLC) and Arduino UNO microcontroller. It employed open loop control with PLC at first and closed loop PID control using Arduino UNO in the latter part of the study. MPU-6050 sensor was used for feedback signals to the Arduino UNO. Point to point motion control method was adopted for this robot arm and simple pick and place applications were carried out using a pneumatic gripper as the end effector. Mainly, the compressibility of air and the overall nonlinearity of the pneumatic servo system made it very difficult to achieve accurate positioning and control with PLC. Closed loop PID control with microcontroller and accelerometer and gyroscope enabled better control with joint angle accuracy of ±1 degrees. The force required by the pneumatic linear actuator to move the robot arm about its joint varied nonlinearly due to the design of the arm. Also, 5/3 directional control valve proved to be ineffective compared to 5/3 proportional valve in controlling the position of the actuators. The joint’s angular displacement was found to be varying roughly linearly with the stroke of the linear actuator and the pressure required to move the arm without any load was found to be around 2.75 bars.