A child with Caudal Regression Syndrome is in need of a therapeutic tricycle to help improve knee flexion.
A child with Caudal Regression Syndrome is in need of a tricycle for mobility as well as therapy. The parents and coordinator of our child would like a bike to not only help with the child’s therapeutic needs but also to be able to get her out and moving freely on her own. Our goal is to help improve the child’s knee flexion while giving her the bicycle riding experience.
1. The Trike needs to support our child’s weight.
2. The Trike needs to be adaptable and able to grow with child.
3. The Trike needs to withstand the forces she can currently exert as well as the in the future as she grows stronger and more capable.
4. The Trike needs to be easily operable for a small child.
5. The Trike needs to help the child progressively increase mobility in her knees.
6. The Trike needs to be fun to ride.
We Researched our basic Designs to see if they were already designed, or for sale. This is what we found
1. Electric/Motorized Tricycle – More faster moving parts that can fail. Battery Powered.
Electric/Motorized Tricycles are for older kids, or drift bikes. They all seem electrically powered, not aided. Could be modified to fit the needs of the child.
2. Traditional Hand Cranked Bike – Hard to steer. Simplest to design / build.
3. Lever Powered Recumbent Bike “Catapult” – Extremely customized. Lacks pedal to create bending in the knees. For adults only.
The design we have chosen will incorporate 2 electric motors. The Main of which will be used to drive the trike, and the secondary one which will operate the therapeutic aspect of the project. The Design will center around a pre-existing trike model that we plan to heavily modify to suit the needs of the child.
The Trike will be a modified version of a pre-existing trike that is common to pre-schools and therapy centers. The front end will have the existing crank set removed and be modified to fit an electric motor. We plan to make the seat adjustable forwards and backwards to accommodate for the child’s growth over time. We intend to meet the therapeutic needs of the child by incorporating a separate crank set farther back on the trike that will be driven by an electric motor. This crank set will allow the child’s legs to be slowly driven in a way that overtime should help to increase knee flexion. The battery as well as controllers for both motors will be located in a dual purpose basket on the rear of the trike. This will allows to waterproof all the critical components and connections as well as providing a convenient carry basket for the child.
Electric Crank Set
Here we calculated the force required for the bike to go up a 20 Degree hill, while in grass. We got the coeffecient of grass from an study done in New Zealand (see reference below). We also created an exel spreadsheet to find to required torque needed to get up this hill without accelerating, with diameter increasing by 1 inch. We could not find any max torque specs for the motor, but we have concluded that since the hub motor we are wanting to use is made to work with the weight of full sized adults, we are assuming that we will have plenty of torque with a 750W motor for her to get around.
Here we are calculating the required force needed for mounting brackets. We are puttng a basket on the back of the bike to put the battery, hub motar controler, a mirco controler, and some buck converter. The mirco controler and the buck converter’s weight we are assuming is neglegable compared to the weight of the battery and the hub motar controlar. We are also assuming that the weight of the basket itself is neglegable. Due to the symetry of the static systm, reaction at point B is going to aid in supporting the loads.
Our finding concludes that the total reaction forces is 24.6lbs. The selection / design of mounting brackets will be based off this calculation. Very likely we will weld the basket to the bike frame instead of mounting it.