Sustainability · User-Centered Design · 2023

Pedal Power Mobile
Phone Charger

A human-powered charging station designed for energy-scarce environments — FEA-validated weldment frame, double-groove pulley transmission, and anthropometric sizing for 5th to 95th percentile users.

Year 2023

Role Project Leader · Lead Mechanical Designer

Institution HTTTC Douala

Duration 3 weeks

Category Sustainability · User-Centered · Electronics

The Problem

Frequent power outages at the University of Douala left students unable to charge their phones, disrupting research, communication, and daily academic life. The problem was not isolated — unreliable electricity is a daily constraint for communities across Cameroon.

As project leader, I assembled a team of three engineering students at HTTTC and set a goal: design and build a human-powered charging solution in three weeks for the Science and Engineering Festival.

The constraints were tight: limited budget, no team experience with weldment design or FEA, and a requirement to accommodate users from the 5th to 95th anthropometric percentile while keeping the device portable enough for field use.

The Approach

We adopted Design for Manufacturing principles and the Empathize-Define-Ideate-Prototype-Test framework. I taught myself advanced SolidWorks weldment techniques and FEA in one week to meet the deadline.

Frame design consumed most of the engineering effort — I iterated through multiple configurations to optimise seat height, handlebar position, and pedal geometry for diverse users, while integrating a double-groove pulley power transmission system and all electronic components within the structure.

When FEA revealed stress concentrations at critical joints under 800+ N loading, I added strategic gusset reinforcements to prevent fatigue failure. Hollow steel tubing was selected for its strength-to-weight ratio, achieving a 40 kg portability target without compromising structural safety. Pulleys and belts were positioned externally for easy interchangeability.

The Outcome

A working prototype was presented at the HTTTC Festival, validating human-powered charging as a viable solution for energy-scarce environments. The simulation-driven design approach prevented structural failures and built confidence in our decisions — reducing costly physical iterations.

This project reinforced a principle I now apply across all design work: optimising for anthropometric diversity is not a constraint — it is the measure of a design's real-world value.

Leading under aggressive deadlines also taught me that technical excellence alone is not enough. Clear task distribution, collaborative design reviews, and patient onboarding of teammates proved equally critical to delivering a working prototype in three weeks.

See the PPMPC in action — Watch the animation on LinkedIn

Technical Documentation