Near-side drive
The inner hand-wheel connects directly to the rear wheel on the user's operating side.
Research and Design Intern
Frido
Formerly Arcatron Mobility
Pune, IndiaJune 2021 - July 2022
A year-long introduction to accessible product development that culminated in a prototype-ready concept for a foldable manual wheelchair that can be propelled and steered with one hand.
The Design Challenge
Independent mobility with one functional arm.
Hemiplegia can leave one side of the body paralyzed, making a standard self-propelled wheelchair difficult to use without assistance. Powered alternatives exist, but they add cost, weight, charging needs, and more components to maintain.
The goal was a fully mechanical chair that offered true one-hand propulsion and steering while staying lightweight, foldable, affordable, and familiar to manufacture.
How It Works
Two hand-wheels, two driven wheels, one operating side.
Two coaxial hand-wheels sit on the same side of the chair. They let the user control each rear wheel independently without reaching across the body or relying on motors and electronics.
Cross-chair transfer
The outer hand-wheel sends torque through a compact transfer mechanism to the far rear wheel.
One-hand steering
Pushing both inputs together moves straight; favoring either input creates the turning moment needed to arc or pivot.
CAD Evidence
SolidWorks views that drove the design decisions.
These CAD views show the concept at the stage where the folding frame, rear wheel layout, caster packaging, and one-hand drive mechanism could be checked together as an assembly.
Full SolidWorks assembly
A complete wheelchair assembly used to evaluate the frame, folding members, footrests, caster placement, and hand-wheel layout.
Side packaging view
A closer side view showing the coaxial wheel layout and the space needed around the rear wheels and front caster modules.
Rear mechanism view
A rear three-quarter view used to reason through axle routing, hand-wheel reach, and the folding constraints around the chair frame.
Designing Around the Fold
Making the mechanism practical, buildable, and serviceable.
01
Split rear axle
An early through-axle blocked the wheelchair's folding path. Replacing it with a two-piece axle and coupler preserved alignment while allowing the chair to collapse.
02
Existing OEM parts
The design reused parts and suppliers already familiar to the factory, reducing new tooling, simplifying service, and keeping the concept closer to production reality.
03
Safer wheel geometry
A low-spoke molded wheel was selected over a bicycle-style rim to balance manufacturing cost, user safety, durability, and practical load distribution.
04
Accessible maintenance
C-clips, reachable rods and cables, standard caster modules, and familiar shop tolerances were retained so common repairs would not require specialized tools.
Learning from the factory
Before designing the chair, I followed the factory workflow from raw steel tube preparation through cutting, bending, tack welding, powder coating, final assembly, and quality inspection. That exposure made the CAD work more grounded in how parts are actually held, joined, checked, stored, repaired, and shipped.
Tube cutting and bending
Tack welding and fixtures
Final assembly
Quality inspection
CAD and prototype skills
SolidWorks became the main design environment for wheel, caster, frame, footrest, armrest, seat, axle, and folding assemblies. I also learned model slicing, PLA print preparation, nozzle and bed temperature setup, and three-axis printer calibration.
CAD decisions checked through assembly and fold-path interference
Supporting CAD Practice
Learning how different gears are modeled.
Before tackling the wheelchair assembly, I practiced modeling common gear geometries in SolidWorks. The exercises developed comfort with revolves, sweeps, helixes, cuts, mirrors, and circular patterns.
Spur gear
Helical gear
Bevel gear
Herringbone gear
Worm gear
Outcome
Prototype-ready, but not released as a product.
I owned the concept from factory study through SolidWorks assemblies and bench-level validation, then presented it for internal prototyping. The company chose not to create a new SKU because regional demand was too narrow for a small manufacturer with portions of production outsourced.
The result was still a complete engineering proposal: a lightweight, mechanical solution that protected folding capability, reused existing parts, and prioritized predictable control and independent mobility.
What I would test next
- Add a selector clutch that locks both hand-wheels together for easier straight-line travel.
- Evaluate a belt or chain transfer to reduce rod-end maintenance without sacrificing foldability.
- Run a structured ergonomics study covering grip diameter, spacing, angle, comfort, and control.
- Build and test a physical prototype with hemiplegic users and rehabilitation professionals.