With advances in modern industries, there exists an inherent need for students to be prepared in areas of robotics and automation for their future careers. While theoretical approaches to robotics education are valuable, a laboratory portion of these classes allows students to apply their knowledge in a real product/system. However, inclusion of such a lab can be difficult due to inaccessibility to useful, real-world robots or high cost of modern robots. This study sought to develop a small, cost-effective robotic arm that students would create during the lab portion of their robotics class as a mode to teach the prototyping, programming, and troubleshooting associated with modern robotics.Prior to this study, an introductory robotics course, ME:4140 Modern Robotics and Automation, was observed at the University of Iowa. While the class includes a lab section, the content it can provide is limited due to the relatively low ratio of robots to students and lack of cohesiveness between labs. Thus, this study sought to interweave prototyping and programming in labs while increasing student access to robots.To achieve such a robotic arm, certain specifications were set. The robotic arm must cost under $100, possess six degrees of freedom, run on simple hardware, and fit within a 12” cube with scalability to larger designs if desired. The idea was to have students work groups of 3-4 over the course of a semester to design, build, and program the arm. This work would culminate in a final project where the robot would have to autonomously achieve some real-world task.Design of this arm was heavily rooted in principles of mathematics and rigid body analysis. Preliminary hand-drawn designs were created based on existing industrial robotic arms and adapted to fit the predefined constraints. The arm was designed from the end-effector to the base with stress analysis performed at each joint. Suitable designs were then modeled using 3D computer aided design software. Models were then optimized to incorporate hardware and motors to operate each joint of the arm. Parts were then ordered or manufactured before the arm was assembled. Finally, the arm was configured to operate using forward kinematics on simple hardware.The final arm design consisted of a 3D printed end-effector that utilized a rack and pinion attached to a linking four-bar to operate a two finger jaw. The gripper was designed to grasp various types of small objects. The body of the arm was constructed from PVC piping due to its strength and low-cost. Joints connecting the PVC were specially-designed, 3D print housings with inset high-strength bearings and stepper motors driving a belt-and-pulley system for rotation. The whole arm was then attached on a lazy susan to allow for 360 degrees of motion. Motor wires for each joint were fed through the housings and PVC to the base where a motor controller and Raspberry Pi were mounted. Simple code developed in Python was used to rotate each joint and the gripper using forward kinematics.Overall, this work was able to create a six degree of freedom robotic arm costing ~$100 that fits into a 12” cube. The arm is capable of retrieving small items and is simple enough that it can be replicated and modified by students. Engaging in this project enables students to gain experience in the design, prototyping, programming, and troubleshooting involved in robotics. With the arm built, future research seeks to create a kit replete with instructions, parts, and code for students to use during their project.

Robotic Arm for Programming, Instruction, and Design (Rapid)

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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