Justin Michaud
2025 Arm
Gearbox
The arm differential used a compact cycloidal gearbox to combine two motor inputs into differential motion for the joint. While the concept functioned and demonstrated the feasibility of the mechanism, the first revision experienced issues under higher loads, compounded by tolerance limitations in the initial design. Due to shifting team priorities, the concept was not further developed within the project, though I plan to revisit and refine the gearbox as a separate personal project in the future.
J2 (Elbow)
The elbow joint (J2) of the arm was developed very late in the build cycle and required a rapid, practical solution to complete the mechanism. The final assembly combined modified metal components with a repurposed leadscrew taken from an Ender 3 printer to create a functional linear actuator driving the joint. While clearly a prototype solution, the system successfully demonstrated the required motion and allowed the arm to operate during testing.
Motors
The arm was actuated using Dynamixel smart servos, which provided a convenient control interface and simplified wiring through their built-in daisy-chain communication. This made integration and control straightforward during development. However, the available torque was relatively low for the size of the arm, requiring large gear reductions that significantly limited motion speed. While they were not the ideal long-term solution for this mechanism, the motors remain useful and will likely be repurposed for future projects that require lower torque.
Gallery
