3-DoF Robotic Arm
NOTE: This webpage and project is still in progress
Project Details
Type
Start Date
End Date
Members
Personal Project
May 2020
Mar 2021 (Paused)
1
Objective
The purpose for a project like this was to prototype and design a robot from the ground up. I could have just bought a robot, but where's the fun in that? A project like this really pushes my knowledge and abilities to the test since it's such a multidisciplined project.
Progress
This project is on hold due to schoolwork. So far, gearboxes, encoders, and arm designs have been finished. The plan is to complete and test the 3 DoF arm via inverse kinematics before attempting to upgrade to a 6 DoF arm.
Encoder Attachment for Stepper Motors
Encoders are expensive and my stepper motors do not have a rear shaft to account for an encoder. This is an attempt to create a cheap attachable quadrature encoder to NEMA stepper motors. Super glue is used to attach the rear shaft. The rear shaft and super glue can be removed with Acetone.
Gearbox Design I
This is the first iteration of the gearbox design. The type of gearbox used is compound planetary gearbox. The issue was that the output shaft is too loose; a bearing will be needed.
Gearbox Design II
This is the second iteration of the gearbox design. A parametrically modeled bearing is now integrated into the compound planetary gearbox design. Output shaft is now more secure than before. However, due to the nature of planetary gears, gear backlash is not prevented.
Gearbox Design III
This is the third iteration of the gearbox design. During research for another type of gearbox other than planetary, I stumbled upon the harmonic drive. Due to the complexity of the drive, I did not have access to the proper materials for the flexible shaft gear. The harmonic drive was not operable with PLA plastic.
Gearbox Design IV
This is the fourth iteration of the gearbox design. After scraping the Harmonic Drive idea, further research into no backlash gear systems lead me to cycloidal drives. So far, this is the most successful iteration of the gearbox I have attempted. There were issues from the home-made bearings such as the wobbling of the plate about the axis of rotation. Although the wobble is minor, the error in precision will propagate through a system such as a robotic arm, which is unacceptable. A proper bearing replacement will be made in the future.
Robot Arm Test I
As of now, it is a 3 degrees of freedom (DoF) system. The purpose of this is to test the functionality of the motors individually.