Skills applied

• Rewired the toy's activation circuit to an external push switch.
• Soldered every new joint and insulated it with heat-shrink tubing.
• Added a plug-and-jack breakaway connection to prevent cord entanglement.
• Verified the build against design requirements and ASTM F963-17.
• Benchmarked build cost against a commercially adapted toy.

Motivation

Standard push-button toys assume fine motor control that many children with motor, cognitive, or sensory impairments do not have. The objective was to improve access to play for children with limited dexterity while keeping the toy safe and affordable.

Technical details

• Baseline toy: one push switch in each lower leg; either triggers audio and mechanical ear movement in a peekaboo or dancing routine.
• The lead from the first internal switch was disconnected and soldered to the external switch, which sits in a small plastic enclosure.
• The peekaboo routine is retained. Both internal switches and the dancing routine were removed.
• Recommended next iteration: remove only one internal switch to preserve more play features, and reduce build labor.

My contribution

• Developed the circuit schematics of the stock and modified drive systems (Figs. 2.3 and 2.4).
• Shared in soldering the new connections, drilling, and assembling the PVC steering bar and seat cushions.
• Authored an individual design report on the team build.

Motivation

Powered wheelchairs are expensive, are seldom available to very young children, and are designed for transportation more than play. Following the Go Baby Go model from the University of Delaware, the objective was an affordable, safe, and customizable powered mobility device built from a commercial ride-on car. Stakeholders were children with developmental disabilities, parents and caregivers, physical therapists, and educators.

Technical details

• Stock circuit: a fused 12 V battery powers a control board whose two relays set motor polarity for forward and reverse. The pedal acts as a push switch.
• The pedal leads were cut, routed up the steering column, and soldered to the GO button. Horn and music buttons were removed; music remains on the dashboard.
• The steering bar is fastened through the wheel with a metal connector and reinforced with polystyrene. Cut PVC ends are capped and taped.
• Foam, yoga-block, and PVC supports attach to the seatback with Velcro, so they reposition as the child grows.
• Recommended next iteration: test stability on a 10° incline with supports installed, and replace hot-glued attachments with mechanical fasteners.

My contribution

• During concept selection, advocated with a teammate for bypassing the remote's buttons with soldered leads, over mechanical dowels that press them. The team adopted the soldered design after the dowel concept failed.
• Helped rewire the remote's PCB to a compact two-AAA battery pack.
• Helped sand the 3D-printed housing.
• Co-authored the design report and co-presented the design review.

Motivation

Go Baby Go chapters and course builds such as Project 02 produce capable mobility devices, but they depend on a nearby chapter, volunteer skill, tools, and permanent changes to the car. Commercial pediatric power mobility costs over $2,000. The objective was a device a caregiver can install without tools or engineering skill.

Technical details

• The remote's PCB was removed from its stock housing and repowered from a compact two-AAA pack.
• Forward, left, and right are kept. Releasing forward stops the car, so a brake input is unnecessary; speed and reverse were removed.
• Each large button closes the same circuit as the original PCB button, so the PCB transmits its original control signals unchanged.
• The housing encloses the PCB, battery pack, and wiring and closes with sunk screws. Velcro straps through its slots let it move between cars.
• Limitation: pairing with a car requires opening the housing once to press two internal buttons.
• Next steps: user testing with children and caregivers, attachment testing on more steering wheels, adjustable button spacing, and extended cycle testing.

Skills in practice

• Building an EMG amplifier on a solderable breadboard, read by an ESP32 microcontroller.
• Filtering EMG to 20–500 Hz and detecting repetitions from a moving-RMS envelope.
• Comparing loads by RMS amplitude and FFT-derived spectral frequency.
• Pairing an electrophysiological signal with a biochemical marker of exertion.

Motivation

Muscle fatigue has both an electrical and a metabolic signature. Measuring surface EMG together with lactate links the electrical activity of the working muscle with its metabolic state.

Test protocol

• Exercises performed to failure under light, medium, and heavy loads.
• EMG compared across loads by RMS amplitude and spectral frequency to distinguish motor unit recruitment patterns.
• In the first light-load recording, a repetition is counted where the moving-RMS envelope rises above the resting threshold (Fig. 4.3).