The 2024-2025 RoboNav team aims to design, build, and test a versatile rover for the University Rover Challenge (URC), simulating Mars exploration. The rover will perform tasks like autonomous navigation, scientific sample analysis, and robotic manipulation. This year’s improvements include a lighter four-wheel suspension, a modular science package, and a redesigned robotic arm to enhance performance and manufacturability, while also fostering member development and interdisciplinary collaboration. 

As a mechanical member of the robotic arm subgroup, I focus on designing, fabricating, and assembling the connections from the shoulder joint to the bicep, the elbow, and the forearm joint. This work is essential for ensuring the arm’s structural integrity and precise motion. Additionally, I serve as a mentor for this year’s Mini Rover Challenge (MRC), guiding new members in mechanical design, manufacturing, and team collaboration to prepare them for contributing to the main rover project. 

Planning Spreadsheet for Determining Lengths and Forces

I collaborated closely with my mechanical lead to design the interface between the cycloidal gearbox and the bicep beam. The connection begins with an aluminum ring featuring 13 precisely drilled holes in a circular pattern, aligned to match the 13 bolt holes on the cycloidal gearbox. This ring is bolted directly to the gearbox to ensure a secure attachment and minimize backlash.

The aluminum tube is then welded to a larger aluminum tube, referred to as the shoulder tube, which features a tightening mechanism consisting of a nut and bolt for additional stability. Attached to the shoulder tube is a resin-printed clamp, engineered to serve multiple purposes. This clamp includes two bolts for radial tightening and three horizontal bolts that interface securely with the carbon fiber bicep beam.

The resin-printed clamp also integrates the mounting system for the elbow joint motor and gearbox. Both components, along with the first timing pulley of the belt-driven system, are bolted from the sides, ensuring alignment and mechanical efficiency. This modular design simplifies assembly and maintenance while maintaining a lightweight yet robust structural connection.

The belt-driven bicep beam is a key structural and functional element of the arm, designed to transfer power efficiently from the elbow joint motor to the rotating elbow joint. The system begins with the elbow joint motor and gearbox powering a 1.312-inch diameter timing pulley positioned at the base of the carbon fiber bicep beam. A 36-inch-long timing belt connects this pulley to a larger 2.125-inch diameter timing pulley located at the opposite end of the beam.

The bicep beam itself is constructed from a 2.125-inch diameter carbon fiber tube, 18 inches in length, selected for its high strength-to-weight ratio. This length was calculated during the kinematic planning phase to ensure the arm could perform all required University Rover Challenge tasks while maintaining optimal structural efficiency.

At the far end of the beam, the 2.125-inch timing pulley is bolted directly into the rotating bracket of the elbow joint, forming a seamless power transmission path. This design prioritizes torque efficiency and minimizes backlash, enabling precise arm movements necessary for competition tasks.

The elbow joint enables precise rotational motion and a robust connection between the bicep and forearm beams. It consists of two primary brackets: a rotating bracket that secures the forearm beam and a stationary bracket that interfaces with the bicep beam. 

The arm assembly integrates precision components for robust performance in the URC. Starting with the cycloidal gearbox as the shoulder joint, it is bolted to an aluminum tube welded to the carbon fiber bicep beam. A motor, timing pulley, and belt system drive the elbow joint, connecting the bicep and forearm beams.

The forearm beam is clamped securely within an aluminum connecting tube and reinforced internally for added strength. At the wrist, dual motor and pulley systems power a differential mechanism for fine rotational and bending control. A slip ring connects the wrist to a precision end effector, enabling intricate tasks required during competition.

This compact and efficient design ensures precise motion and durability for demanding operations.

Full Assembly with Arm

Full Assembly with Science Module

• Challenge: Maintaining structural integrity under load required robust connections that avoided dependence on resin-printed components. 

• Solution: To address this, a bolted aluminum ring was welded directly to the cycloidal gearbox and bicep beam tube for enhanced strength. Additionally, a top and bottom plate were used to secure the stationary bracket, ensuring reliable support for the elbow joint. The rotating bracket was fabricated entirely from aluminum for durability. To further reinforce the elbow joint, an aluminum tube with clamping force was bolted through the stationary bracket and forearm beam, providing a secure interface. 

As an MRC mentor, I am helping new members develop their skills in designing and fabricating mini rovers. My work emphasizes practical solutions based on my past experience and new skills, ensuring that the team works effectively and efficiently. 

I assist the team of new members throughout the design and fabrication process. This includes guiding them in making decisions, helping with presentations, and providing practical design solutions based on my previous experience and new skills. Likewise, I serve as their first point of contact for all things RoboNav related.

My team came in first place in our in-house MRC competition in February 2025. They built a robot that could successfully traverse the environment and manipulate objects, including a rack-and-pinion mechanism to push buttons and a 2-DOF arm to move buckets.