Up, Step, Go = Learn, Develop, Grow!

Walking Aid for Children with Developmental Delay

Presented By: Michelle Vito-SchaakeBachelor of Engineering (Biomedical)

Supervisors: David Hobbs & Laura De Palma

ENGR5710A and B: Results Seminar(9 Units)

Product Objective Aims to provide a walking aid for children (1-

2.5yrs old)with gross motor Developmental Delay, which encourages gait and muscle strengthening. Resistance settings for muscle strengthening Provides a stable base for a standing or walking

toddler Gait training ability Room for growth Child and user friendly

Kim Sim Lee (BME Masters) Initated project in 2012 Developmental Delay, Market Analysis Possible geometric structure of product

My Project Objective Control System

The product’s Control System aims to provide the following: Braking Mechanism: To further enhance anti-tipping

feature, as well as provide safety and assurance for toddler and parent

Toddler Training Modes: To strengthen muscles and furthermore, encourage and challenge the child to stand up and walk

Developmental Delay (DD) Developmental Delay (DD)

is defined as an ongoing development lag where a child does meet their developmental milestones within the expected age bracket.

It affects the child’s ability to learn and develop new skills, but does not affect their ability to physically grow.

Two clinical groups: Transient and Persistent

Social

Intellectual

Language

Fine Motor

Gross Motor

Previous Studies Cerebral Palsy : A form of

persistent DD Studies have shown muscle

strengthening does NOT significantly affect their ability to walk

Children with CP have different muscle structure and struggle with the control of their limbs

Children with transient DD have normal developing muscles

Gait Development and Analysis Most children are able to walk

after 18 months. Children with DD learn to walk

at a later stage, therefore they are heavier.

EMG studies show variation is walking speed can trigger new muscle patterns A.R Den Otter, A. G. (2004).

Speed Related Changes in Muscle Activity From Normal to Very Slow Walking Speeds . Gait and Posture, 19,270-278.

Current Walkers

Kaye Walker

Rifton Gait Trainer

Kid WalkBoikido Wooden Wagon Walker

Common baby walkers. Banned in Canada since 2004

Problem Statement

There are no existing walkers available in the market for toddlers with gross motor DD

Project Process and Progress

Literature review – understanding developmental delay and gait

Defining the specifications of the project

Conceptualization of the system Selecting components of the design Component Testing

Current Stage

Engineering Design Process

Requirements & Specifications Light weight Able to carry 30kg load max weight of child is approx. 25kg

Encourage leg strengthening – resistance training

Encourage walking Able to apply to existing walkers without

making it look like a walker for children with DD

Velocity range: 0 m/second – 0.4167 or 0.5556 m/second (1.5 – 2km/hr)

Conceptualization

Project aim had two tasks: Braking and Muscle Strengthening

systems Primary focus was braking:

Basic Start/Stop – push buttons Brake pad

Shifting the primary focus to gross motor muscle training

Morphological & Weight Chart

Name Brakes(0.25)

Variable Resistance(0.25)

Energy Efficient(0.16)

Bulky and Heavy(0.16)

Safe(0.25)

Cost(0.16)

Total

Bike Brake Yes (0.15) Yes (0.15) Yes (0.096) Likely (0.048)

Likely (0.075)

Likely (0.048)

0.5670

Automation trolley brake

Yes (0.15) No (0.025) Yes (0.096) Likely (0.048)

Yes (0.15) Likely (0.048)

0.5170

Centred Ring on Axial

Yes (0.15) Yes (0.15) Likely (0.048)

No (0.096) Yes (0.15) Likely(0.048)

0.6420

Gear system

Yes (0.15) Yes (0.15) Likely (0.048)

Yes (0.016) Likely (0.075)

Likely (0.048)

0.4870

Rod/ pistol Yes (0.15) No (0.025) Yes (0.096) No (0.096) Likely (0.075)

Yes (0.096) 0.5380

Fifth wheel system

Yes (0.15) 

Yes (0.15) Likely (0.048)

No (0.096) Yes (0.15) Likely (0.048)

0.6420

DC motor Driven System (x4 WD)

Yes (0.15) Yes (0.15) Yes (0.096) Likely(0.048) Yes (0.15) Yes (0.096) 0.69

Colour Probability (%)

  60  30  10

Selected Design

H-BridgeMotor Driver

Microcontroller

Sensor measuring Velocity

∑Input (Force) Output

(Force)

Stage Aims to Encourage…

1 Standing and balance

2 Taking the first steps

3 Taking more steps with resistance

4 Walking with resistance

Design Justification Advantages

Based on the weight chart it is the more logical solution

Fulfils both sections of the design task – Braking and resistance training

Slight changes can be applied to suit most systems

Cost efficient Disadvantage

Cannot be applied to all systems

Battery dependent

Manufacturing & Test Model

Engineering Block Diagram

H-BridgeL293D

Motor Driver

DC Motor50:1

Microcontroller

Arduino uC32

Sensor measuring

VelocityQuadrature

Encoder

∑Input (Force) Output

(Force)

Electronic Components

Component Testing

Mode Setting: Sends 1 pulse of voltage over a certain period of time to the DC motor.

Where:0 =1000 µs (Forward)90 = 1500 µs (Stop)180 = 2000 µs (reverse)

Component Testing Results Indications of error

involved: Unexpected behaviour Disagreement with

specifications Inconsistent data between

two power sources with the same input voltage

Problems with code?

0

22.2

5 450

1

2

3

4

5

6

Motor Setting (0-45) vs Km/hr (10 cm)

Km/hr (10 cm)

Motor Mode

Velocity (km/hr)

022

.5 4567

.50

0.51

1.52

2.5

Motor Setting vs KM/hr(10cm wheel)

KM/hr(10cm)

Motor Setting

velo

cit

y (

km

/hr)

External Testing Needed an external validation method. Testing solution – the use of a tachometer

DC regulated power source DC motor, arduino

and motor driver

Tachometer

External Testing Results

Time (minutes) Voltage 6V 9V 12V

1 59.62 rpm 70.36 rpm 121.89 rpm2 59.75 rpm 71.1 rpm 121.86 rpm3 59.62 rpm 71.19 rpm 122.45 rpm

4 60.09 rpm 70.86 rpm 122.16 rpmAverage rpm (rpm ± SD) 59.77 rpm ± 0.22 70.8775 rpm ± 0.37 122.09 rpm ± 0.28

Tachometer 59 rpm 70 rpm 121 rpmm/min 5.9 7 12.1

m/second 0.098 0.116 0.201

Revolutions per Minute (RPM) at set Voltage and PWM (Encoder Setting = 45) Of DC motor with a 10cm wheel

Reasons:• Inconsistent power source• Lack of knowledge and understanding of

the DC motor’s behaviour

Future Work Implement and test the circuit

design Modification and improve design

(dependent on time) Communication of final design

Thesis Report Expo and poster

Knowledge Gaps: Implementing a PID Defining the boundaries of each training stage Weight of the overall system Alternate power source in order to keep motor

running consistantly

Engineering Design Process

Conclusion There are no existing walkers, customised for

toddlers with DD Engineering design method - enables to

evaluate solutions in a logical and thorough manner.

End of year goal: To have a working prototype of a walking aid for children with gross motor DD.