Elastic-Band Powered Vehicle: Precision Roller System
This project involved the end-to-end design of an elastic-band-powered vehicle able to travel 10 metres, maintain a straight trajectory, and pass through goal posts 1 metre apart without external assistance. The system had to be fabricated entirely from repurposed wood, metal, and plastic, using only elastic potential energy as its propulsion source. My final system achieved the closest approach to the goal of any team, travelling 9 metres with a clean, straight path on the second attempt.
Problem
To construct a vehicle/system using only repurposed materials with propulsion limited exclusively to elastic bands. No pushing, slingshotting, or assisted release permitted. The entire system must travel as a unified vehicle, begin motion autonomously upon release, travel on the floor surface, move in a straight path, and fit between 1-metre-wide posts. Full design documentation required including 20-node problem structure, multi-level objective tree, function analysis diagram, photographs, and full PDF report.
Approach
The chosen architecture was a central-shaft elastic torsion roller system, in which the entire cylindrical body acted as the wheel, axle, and chassis simultaneously. This provided excellent directional stability and reduced lateral drift.
Key design elements included: full-body roller geometry (maximised moment of inertia and promoted straight-path stability), central wire shaft (enabled efficient elastic torsion loading with minimal energy loss), poster-board discs (ensured rotational symmetry and balanced mass distribution), repurposed-material frame (integrated wood, metal, and plastic components), minimal friction bearings (reduced energy loss), and two-band winding system (allowed controlled torque build-up and smoother energy release).
Three design pathways were explored: axle-car configuration, multi-wheel elastic pull-back design, and full-body roller vehicle. The roller configuration was selected for its superior straight-line stability and repeatability.
Methods & Tools
- Mechanical system design under material and energy constraints
- Problem structuring (20+ nodes)
- Hierarchical objective definition
- Functional decomposition and systems thinking
- Low-friction mechanical design
- Torque storage and controlled energy release
- Fabrication precision using repurposed materials
- Analytical reporting and engineering communication
- Reliability engineering through iterative refinement
Outcome
- Attempt 1: 4 m
- Attempt 2: 9 m (nearest to target of any team)
- Received 10/10 for sketches & direction
- Received 10/10 for physical prototype
- Received 5/5 for submission draft
- Awarded 8/10 for achieved goal
- Awarded 13/15 for distance travelled
- Awarded 13/15 for path of travel
- Awarded 18/20 for vehicle impression
- Awarded 15/15 for submission form
- Instructor requested to use project as example of 'excellent submission'
- Post-test: hit target 5 consecutive times after minor adjustments
- Overall Grade: 92/100 (A+)
Key Leverage
This project underscored the profound impact of disciplined systems thinking on physical performance. By treating torque delivery, rotational symmetry, and frictional inefficiencies as interconnected subsystems, I built a vehicle capable of near-perfect straight-line stability. Achieving the closest result in class—and ultimately reaching five consecutive successes—demonstrated the value of methodical iteration and precision in mechanical execution.