Embedded Files
Northeastern University Senior Capstone Project | Fall 2025
R.E.V.A.N. Capstone Day Presentation
Overview
Overview
R.E.V.A.N. is a modular 3 to 6-DOF robotic arm educational kit designed to make robotics accessible to students of all skill levels. The key innovation that makes this possible is the modular, swappable joints.
Our result is a low-cost ($586), lightweight (5.2kg), safe educational platform that is fully customizable. A user can begin with 3-DOF and expand the arm as they learn more about kinematics.
Challenge
Challenge
Educational robotics kits are expensive ($8,000+)
Complex assembly and limited versatility
Barriers to entry for students and institutions
Solution
Solution
Robotic arm that can expand from 3-DOF to 6-DOF using swappable joints
Reconfigurable to take the place of multiple arms
3D printed parts for affordability
Wiring connected to one Arduino Mega in the base
Safe, cobot-inspired design to minimize pinch points
Design Process
Design Process
At the beginning of the Capstone program, our team split into two groups to focus on the mechanical and electrical parts of the project. I was a part of the mechanical team, which focused on designing:
42:1 and 30:1 gearboxes
Joint and link design
Swappability interface
Full CAD Model of R.E.V.A.N.
30:1 Two-Stage Cycloidal Gearbox
30:1 Two-Stage Cycloidal Gearbox
A cycloidal gearbox was chosen due to its high torque-to-weight capacity and distributed contact pressure across the gear lobes. They are also non-backdrivable due to their eccentric nature, allowing the gearbox to lock in place. This design was iterated upon many times in order to ensure enough torque was exerted.
Swappable Joint
Swappable Joint
The joint is made up of a NEMA-17 stepper motor, with the gearbox attached to the top of it. The external parts are 3D printed and fastened together using a combination of socket head screws, nuts, and heat-set inserts. Each joint also has enough space for wires to pass through the sides.
Swappable Interface
Swappable Interface
This interface was designed to be easy for a student to use, but also to be mechanically rigid to transfer torque. It also had to properly connect the electrical components together, meaning wiring would have to be able to seamlessly connect to other joints. We used a spring plunger system to easily connect and disconnect the joints.
Control System
Control System
To control the arm, we wired everything through an Arduino Mega. Each joint required a TMC2209 motor driver for Arduino control, a magnetic reed switch for calibration, and a resistor for joint and link identification. Each joint required four separate signals:
One to control motor movement
One to control motor direction
One to detect the joint's calibration position
One to identify the joint
Electrical Schematic for a Single Swappable Joint
FEA Analysis of Cycloidal Gear
Structural Analysis
Structural Analysis
FEA was performed on the gearbox, as that was the main component that would experience maximum torque.
Solidworks was used to perform a simple analysis based on the input torque of 0.45Nm, and the gear lobes were analyzed based on contact with the stationary outer ring rods.
The maximum Von Mises stress was found to be 13.2 MPa. Our chosen material was Onyx, which has a yield strength of 40 MPa, well below our stress experienced.
Results & Impact
Results & Impact
Our team created this project to lower the barrier to entry to robotics for students. We built differing joints and links to serve as educational tools for teaching about robotic concepts. Our self-contained joints and quick-disconnect system achieve an interchangeable design, using a simple pull-and-twist to lock or unlock the joints.
Final Specs:
Height: 32 inches
Weight: 5.2kg
Cost: $586 (full 6-DOF), $376 (3-DOF)
DOF: 3-6 (modular)
Acknowledgements and Further Info
Acknowledgements and Further Info
This project would not have been possible without the tireless work of my Capstone teammates John Chen, Alexander Feuer, Sarah Rescsanski, and Eric Wong. I also owe many thanks to our Capstone advisor, Professor Ahmad Nourian, who assisted us through the whole process.
If you are interested in more about this project, you can read our Executive Summary here, as well as find our final presentation.
Page updated
Google Sites
Report abuse