Rice Robotics

I joined Rice Robotics’ BattleBots team partway through a season and worked primarily on mechanical design for two 1 lb-class robots. The baseline layout was a two-wheel drive platform with a front-mounted spinning weapon. My role focused on weapon and armor geometry, materials selection, weight optimization, motor integration, and making the chassis robust enough to survive repeated impacts while remaining competitive in the arena.

Context and design goals

BattleBots is a head-to-head competition where small design decisions determine whether a robot survives a hit or delivers a decisive strike. We chose the 1 lb class to keep the project accessible and rapid to iterate. From the outset I was tasked with refining a concept already chosen by the team: maximize offensive reach and impact with a front spinner, protect vulnerable subsystems with minimal forward armor, and shave mass aggressively so the robot met the strict weight limit without sacrificing performance.

Robot 1 — Team build: challenges, experiments, and engineering solutions

Our first full-scale team robot was nearly double the target mass after the first prints and assemblies. The weapon, manufactured from solid steel, and full-coverage printed armor were the largest contributors. Early arena tests exposed three clear failure modes: the carbon-fiber top and bottom plates flexed under load and eventually fractured, the weapon often failed to deliver consistently damaging hits, and the robot lacked traction and pushing ability.

To address the weapon mass and energy-transfer problem I redesigned the weapon geometry to deliver comparable or greater momentum while reducing mass from roughly 88 g to about 55 g. This required analyzing how impact impulse is delivered over strike duration and adopting geometry used successfully in other small spinners. The result preserved peak force while lowering inertial cost.

For chassis rigidity I increased plate thickness and added three thicker carbon-fiber reinforcement spokes beneath the chassis oriented toward the weapon. Attempts to replace composite plates with 3D-printed carbon-fiber filament were unsuccessful; iterating back to thicker composite plates with additional internal reinforcement reduced flex and vibration enough to avoid repeat catastrophic failure. To recover traction I redesigned the wheels from a flat TPU band around a PLA shell to a printed tread pattern and sourced a higher-traction, rubber-like TPU. The new tread formulation and pattern increased push ability dramatically.

Finally, experiments with weapon RPM revealed that our weapon was spinning too fast for effective energy transfer: at high angular velocity the blade tended to swipe past opponents without engaging long enough to transfer peak impulse. I implemented a gear reduction that lowered RPM while keeping torque, increasing contact time per strike and improving hit effectiveness.

Testing validated the main concepts: the robot won an opening match and subsequent modifications improved strike performance, but continued limitations in maneuverability and carbon-fiber fatigue highlighted the need for further stress forecasting and more practice time in driver training. Throughout this phase I coordinated print runs, staged motor tests, and prioritized incremental weight cuts based on measured contributions to total mass rather than intuition alone.

Robot 2 — Personal prototype: full design ownership and outcomes

For my next semester I led a personal design entered in an internal club tournament. I intentionally designed a compact barrel-style robot to leverage dense, localized impacts and flipping ability that are well suited to rapid 3D-printed prototyping. The weapon evolved from a helix concept to a flat lip and finally to a modified triangular cross-section along the barrel; the triangular profile produced consistent catch points for flipping while remaining printable in TPU and structurally simpler than the helix.

Material choices reflected the tradeoffs between stiffness and energy absorption. Most components were printed in TPU and PLA to speed iteration, while top and bottom armor used thicker PLA in lieu of very thin carbon fiber to mitigate the top-down failures we had previously observed. Integrating the weapon motor directly into the barrel maximized the effective strike footprint, but required precise mating features so the motor could be pinned in place without excess material. Because the motor and electronics budget was tightly constrained—roughly 175–200 g allowance—I designed minimal printed standoffs and clips to secure internals and wiring; this reduced internal migration during impacts and improved repairability.

In competition the barrel robot won its opening match, tied the second, and forfeited the third due to limited repair time. The design placed around third to fourth out of roughly a dozen entries. The barrel geometry proved effective at flipping opponents but was vulnerable to brittle failure under very hard impacts. Front-heavy mass distribution aided under-robot engagements but risked nosing into the floor if the robot length increased. I documented these findings and the compact-mount techniques so teammates could adopt the lessons in their own builds.

Technical skills and engineering judgment demonstrated

I executed multiple full design cycles that balanced mass, stiffness, and energy delivery. I applied momentum- and impulse-based thinking when downsizing weapon mass, used iterative prototyping to select materials (PLA, TPU variants, and carbon-fiber composites) that met competing demands for stiffness and impact absorption, and implemented mechanical reinforcements to reduce resonance and catastrophic failure. I tuned drivetrain and weapon gearing based on observed dynamic behavior rather than nominal motor specs, embedding motors where necessary to maximize weapon footprint while minimizing chassis complexity.

Beyond part design, I established compact mounting strategies for motors and electronics that minimized material and mass while dramatically increasing internal stability. I displaced guesswork with targeted tests—mass audits, RPM vs. strike-duration trials, traction pattern comparisons—and used those data-driven results to prioritize design changes that returned the greatest performance per gram removed.

Outcomes and practical impact

The team robot demonstrated that careful weapon geometry and reinforced carbon-fiber structure could produce reliable performance at 1 lb scale, winning a match and informing subsequent chassis revisions. The personal barrel robot validated a compact, motor-embedded approach that other members cited when improving their own builds. Practices I introduced—secure internal mounting and conservative mass budgeting tied to measured part contributions—were adopted across the group and improved repairability and reliability in later iterations.

Closing reflection

The BattleBots projects at Rice Robotics sharpened my ability to make systems-level tradeoffs under strict mass and manufacturability constraints. I learned to combine dynamic reasoning about impacts with practical prototyping and materials selection to produce robust, competitive machines. The process of iterating designs, diagnosing failure modes, and implementing targeted fixes prepared me to tackle larger mechanical systems where similar tradeoffs between materials, dynamics, and manufacturability are critical.

Here we see the top down of the Pancake 2.0, which had individual motors for the wheels and the upgraded weapon and chassis which I worked on.

Two weapon designs, with the newer, rebalanced design on the left and the older design on the right.

Weapon motor, which despite the size had significantly max torque, then comparable bots.