Hardware UX · Research & Fabrication

Designing a steering experience for lunar terrain

For the 2026 NASA Human Exploration Rover Challenge (Apr 9–11, Huntsville, AL), I led the human-centered process of deciding which steering architecture gave riders the best control, comfort, and confidence on simulated lunar and Martian terrain — then fabricated it.

Role

UX Research Lead (Steering) · Designer & Fabricator

Timeline

Sep–Dec 2025

Team

Wendy Tang · Ray Liu · Adhvik Aggarwal · Raúl Falcón

Tools

SolidWorks · Fusion360 · SLA/FDM · Carbon Fiber

The UX Challenge

Steering as a control experience, not just a mechanism

How might we design a steering system that lets exhausted riders maintain precise control over unpredictable terrain — while preserving comfort, legroom, chassis clearance, and mechanical efficiency?

The drivers had to maneuver through harsh obstacles under physical load, with limited visibility, a confined riding position, and constant suspension movement. The best system wouldn’t just turn the wheels; it would help riders feel stable, confident, and in control.

50°

Target steering angle under extreme driver load

9 ft

Targeted turning radius

94 lb

NASA-mandated maximum vehicle weight

Research · From Sketch to Linkage

Start cheap, fail fast, learn the motion

Before committing to carbon, we explored the steering motion in pencil and cardboard. Hand sketches mapped how rider input should translate to wheel angle, and low-fidelity four-bar linkages let us feel the geometry and catch problems early — for the cost of a sheet of MDF.

Early steering sketches and cardboard linkage mockups — Starting point — hand sketches and laser-cut linkages to study the motion.

Low-fidelity four-bar steering linkage prototype in MDF — A low-fidelity four-bar linkage — cheap to build, fast to test.

Research · Testing Architectures

Horizontal handlebar vs. Cranker Four-Bar

We compared two steering concepts through prototype testing and rider feedback. The Indirect Bearing (IB) handlebar was instantly familiar — riders understood it immediately and it resisted unintended forces well. But its layout fought our chassis geometry, creating tie-rod offset, packaging conflicts, and bump-steer risk that would make steering less predictable on rough terrain.

The Cranker Four-Bar (C4B) felt less familiar at first, but its perpendicular dual-crank linkage allowed a cleaner tie-rod path and better chassis integration — isolating rider input from terrain feedback for a more consistent, controllable response.

Indirect Bearing horizontal handlebar steering prototype — Indirect Bearing (IB) handlebar — familiar, but constrained by chassis geometry.

Cranker Four-Bar steering prototype — Cranker Four-Bar (C4B) — less familiar, but a cleaner, more terrain-ready linkage.

User Testing & Feedback

Familiarity didn’t guarantee better performance

We put both systems in front of riders. The handlebar felt more natural at first, but testing showed the crank reduced packaging conflicts and gave a more controllable, terrain-ready steering path. This footage is the central artifact behind the design decision.

User Testing — Handlebar vs. Crank · NASA x RISD Rover Steering.

Familiar ≠ better

Riders adapted to the handlebar instantly, but familiarity alone didn’t produce the most controllable steering.

Fewer conflicts

The crank reduced tie-rod offset and packaging conflicts, smoothing the steering path over obstacles.

Confidence over terrain

Feedback helped us balance intuitiveness, control, clearance, and confidence under load.

The Decision

A UX decision matrix, not a mechanical preference

We chose the C4B not because it was mechanically cooler, but because it delivered the strongest total experience under competition constraints — predictable response, reduced chassis interference, and room to evolve around the rider.

UX Criteria	Horizontal Handlebar / IB	Cranker Four-Bar / C4B
Familiarity	Strong — similar to bike/trike steering	Moderate — required rider adaptation
Sturdiness	Strong — resisted unintended rider forces	Moderate — vertical handlebar more exposed
Packaging	Weak — chassis geometry caused tie-rod offset	Strong — cleaner linkage path
Rough-terrain control	Weaker — bump-steer risk	Stronger — more consistent turn response
Leg clearance	Constrained by chassis and rider position	Improved through later iterations
Final UX fit	Familiar but mechanically compromised	Less familiar, but more controllable and terrain-ready

Final direction

Cranker Four-Bar Steering System

Iteration · Designing Around the Rider

Seven versions, each solving a real rider problem

Between Version 1 and Version 7, the geometry was entirely overhauled. Each iteration responded to a specific user or terrain problem — turning the steering into an ergonomic interface between rider, chassis, and terrain.

V1–V2 · Steering angle

Elongated the sidebars to widen the steering range and tighten the turning radius.

V2–V3 · Ground clearance

Shifted pivot points above the center tube so the mechanism wouldn’t strike obstacles during suspension travel.

V4–V5 · Leg clearance

Offset side pivots outward and added dual handlebars to keep clear of the drivers’ legs.

Major obstacles and improvements across steering versions V1–V7 — V1–V7 — each geometry change mapped to a control, clearance, or terrain problem.

Orthographic dimensions of the final crank steering system — Orthographic views & dimensions of the final Crank Steering System.

Fabrication · Built for Feel

Lighter, smoother, stronger — for the rider

Once the C4B was validated, I helped translate it into a lightweight, durable assembly. Every fabrication choice mapped back to the rider experience: less fatigue, more predictable steering, better reliability during competition.

Carbon fiber linkages

Thin-walled carbon tubing cut weight while preserving rigidity — less mass for the rider to fight.

3D-printed internal supports

LW-PLA inserts embedded in wet layups reinforced high-stress joints for durability.

Low-friction bushings

SLS-printed bushings and shoulder bolts kept actuation smooth under heavy rider load.

Cutting carbon fiber cloth for the steering linkages — Cutting carbon fiber for the steering linkages.

Layered carbon fiber crank steering component — A laid-up carbon crank component before trimming and integration.

Documentation & Technical Storytelling

Communicating the decision

I served as technical editor for the steering section of our 100+ page NASA Design Review — translating prototype results and tradeoffs into a clear narrative for NASA reviewers, with rigorous citation accuracy for safety review.

NASA Phoenix Award · Greatest improvement between reports

Our documentation earned the NASA Phoenix Award for the greatest improvement between reports.

Excerpt from the NASA Design Review report — Excerpt from the 100+ page NASA Design Review report.

Validation · Real Riders

Putting real bodies on the final build

The truest test of a steering UX is people actually riding it. We put teammates of different heights and builds on the finished rover — confirming the seating position, leg clearance, and steering reach worked for real riders, not just the CAD model.

Two riders seated on the finished RISD Rover — Two riders on the finished rover — validating riding position and steering reach.

Rider steering the RISD Rover along a riverfront path — Solo riding test — checking control and comfort on the move.

Two teammates riding the RISD Rover on a brick path — Different riders, same rover — ergonomics that hold across body types.

Close-up of the final crank steering system in use while riding — The final Cranker Four-Bar steering in use — hands on the crank, wheels tracking true.

Fits real bodies

Cockpit, legroom, and reach validated across riders of different heights and builds.

Confident control

Riders kept a stable, predictable hold on the crank while pedaling under load.

Ready for terrain

Clean tracking on flat ground translated to composure over obstacles at the challenge.

Outcome

A steering system designed around the rider

The final Cranker Four-Bar system turned CAD exploration into a race-ready carbon-fiber assembly on the RISD Rover chassis — selected by testing architectures, listening to riders, and iterating around real ergonomic constraints.

Final render of the Cranker Four-Bar steering system — Final Cranker Four-Bar (C4B) steering assembly — render.

Steering assembly integrated onto the RISD Rover chassis — The C4B steering integrated onto the race-ready RISD Rover.

RISD Rover team holding the finished rover at NASA HERC 2026 — RISD Rover Team — NASA HERC 2026, U.S. Space & Rocket Center, Huntsville, AL.

Demo — NASA x RISD Rover · Final Crank Steering (May 2026).

Rider taking the RISD Rover over an obstacle at NASA HERC 2026 — Where it all comes together — controlled, confident steering over real terrain at NASA HERC 2026.

Next project

CurioXR

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