July - December 2025 (currently in progress)
Problem Statement:
To design a safe, low-cost, three-to-six degree-of-freedom robot arm that features swappable joints to maximize versatility as an educational tool.
The design consists of two parts: The permanent lower 3 joints and the swappable upper 3 joints. Each joint, permanent and swappable, is a self-contained unit with a gearbox and motor. The joints are connected by links; the permanent lower 3 links and the swappable upper 3 links. The quick disconnect mechanism consists of a spring plunger that locks the rotating part of the joint to the link. REVAN is held down by a baseplate that clamps onto tables.
A topology study is a simulation in SolidWorks where you can import an assembly and all loads on that assembly. The simulation shows what material is required for the load and what is in excess. We have also redesigned these links to have a properly aligned center of mass. Our preliminary designs were misaligned and needed to be changed for proper design specs. Based on this study, our team was able to have a mass reduction of 38% in our links from iteration 1 to 4.
Our gearboxes will by cycloidal drives, meaning that the loading is eccentric. We choose this style of gearbox because it outputs high torque, is strong, and does not have backlash. We will have 2 versions of these gearboxes. One will be a 30:1 ratio for the lower 3 joints, and the other will be a 15:1 ratio for the upper joints. These gear ratios were calculated off the robots weight and our chosen motor (NEMA 17). We are 3D printing these gearboxes for budget constraints; however, we would like to machine them in the future.
Our design is quick-swappable, meaning that the upper 3 joints can swap in-and-out with other joints. This mechanism is done by a spring plunger. It clicks into place and holds firm. To release it, you simply push inwards with a force and then twist/pull to take off the joint. We are currently performing validation on this design.
Below is the poster my team created for our first poster session in Capstone 2. This is an overview of all the work we have currently completed, and a display of all the work we have yet to accomplish. I am very proud of this milestone and will continue to work hard on this.
The next stage of this project is 3D printing and building our joints to begin testing and validating our system. Please stay tuned for these updates in the coming months!