Gait Trainer Support Device

Project Overview

Designed, prototyped, and tested a detachable and universal head and neck support device. This improved patient outcomes for children with developmental disabilities. Additionally, created a manufacturing manual for caregivers to recreate the device using COTS parts.

Project Duration

3 months

Skills

Solidworks, prototyping, manufacturing, project management, customer needs analysis, FMEA, stress simulation

Design Requirements

Stakeholders included parents, patients, and physical therapists. Additional sources were referenced to translate customer needs into quantitative targets.

no PVC

Suitable for patients aged 5-10
Lightweight (<4.5 kg)
<10m setup time
Low cost
Easily recreatable by parents with limited manufacturing knowledge

20-35 degree headrest angle

No latex
Quick release attachments
Provide adequate head support (assuming 6.4 Nm torque)
No sharp edges or points
Surfaces easily sanitizable between patients

Cobbs angle at 35 and 45 degrees

Cobb's angle is used to measure the curvature of the spine. A healthy neutral range is 20-35 degrees, therefore the headrest should only be designed to allow for this range of motion, although the caretaker can adjust the angle within this range based on the patient's needs.

Head and Neck Length = 0.16 m

Head Weight = 4.3 kg

Head and Neck CG = 0.09 m

Force = m*g = 42.1 N

Torque = r * F *sin(θ) = 1.6 Nm

With a safety factor of 4, this torque becomes 6.4 Nm

Force calculations for head and neck

Additional anthropometric data was used to calculate the mid-waist to head length range of the population, informing the device's required vertical adjustment range.

Concept Generation + Chosen Design

A function tree clarified the specific goals of the project, leading to the chosen design.

Function Tree

Chosen Design

The chosen design consists of two perpendicular canes, each of which are able to adjust length, allowing for the device's frontal and transverse motion. These canes are held together by a T-joint, and the headrest consists of a neck pillow to support and pad the patient's head, as well as a gooseneck to adjust the side panel angles. A more detailed depiction of the final design can be seen below.

Materials Selection

The neck pillow was chosen based on its Indentation Load Deflection (ILD) rating of 36 lbs, which provides comfort while also maintaining adequate support. More information on these specifications can be found via the ASTM D2574 standards.

Simulation

Device's von Mises stress under expected loading

Device displacement under expected loading

Device displacement under large loads (534 N)

According to the simulations, expected loading does not cause excessive deformation or stresses resulting in failure. However, under large loads, this device could experience high stresses and displacements, although not to fracture. The device clamps are also expected to fail prior to material deformation, so the patient's safety will be maintained.

Testing

Medical device standards informed the empirical testing for this device, as described and shown below.

Drop Test: Device is dropped from a height of 1 meter, then inspected for damage that could impair the device function.

Occiput Support Test: The 6.4Nm torque is applied to the headrest portion of the device.

Stability Test: Gait trainer is overbalanced by 10 degrees, testing whether the support device falls or unattaches.

Drop

Occiput Support

Stability

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