Prototypes

The goal of our project is to develop and build a powered wheelchair in 10 months. This requires a tight timetable and there is not much room for errors. As a result of this timeframe it is not possible to make a prototype of each module to make sure it is working properly. These modules are: chair, frame, battery system, support system, balancing, tracks, tilt mechanism and drive chain.
We sorted the systems according to their risk and impact on our final system. We decided to build and test the three most critical systems which are crucial for a successful product. These are the balancing system, the clutch and the tracks.

 

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The balancing system shall consist of a Segway-like construction. We wanted to use as many of the final parts as possible. This means using a chain to drive the wheels, the motors and controllers as well as the IMU planned for the final version.

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The clutch prototype shall consist of the clutch, a servo motor and an encoder as well as a drive motor. We want to figure out if using a single lever has enough force or if additional constructive measurements have to be made. Also we want to read if the clutch is opened or closed using the encoder built in the servo motor.

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The goal of the track prototype is to test the behaviour on the stairs. We calculated the required strength and made estimations for the friction coefficient. Nevertheless it is important to compare this theoretical values with practical experience. For this reason we manufactured a prototype which takes advantage of the tensioning mechanism and the tracks we ordered. For propulsion we used replacement motors from Maxon which give us the same torque as the final ones but at a lower speed.

Focus Project

Focus projects are projects for students of mechanical engineering in the last year of the bachelor. Sometimes students of electric engineering join them to help with the electronics. In most of the projects the goal is to build a prototype of a product you could sell. To achieve that there are also industrial designers from the ZHdK that help build the prototype.

The main purpose of those projects are the didactic. In some projects there were also patents applied.

This is a list of some focus projects from the ETH:

Story

In this post is about our vision and our product and how we got there.

IDEA

Early in 2013 all students of Mech. Eng. were informed about the focus projects an the ETH. Focus projects are designed to put the knowledge acquired at ETH to practical use. Most projects are initiated by professors and their department. Nevertheless students have the opportunity to apply for a project of their own.

Our project began with an idea of Beni Winter, he wanted to develop a robot able to climb stairs. This machine should balance on one wheel and transport a camera for the purpose of filming. Basically something like the rezero able to film and climb stairs with a high degree of agility. After a couple of meetings with Prof. Sigwart we decided to build a wheelchair capable of climbing stairs. The project got accepted and we presented it all other colleges. This resulted in a team of seven Mech. Eng. students and one electrical engineer. To give our product a good design two Zhdk students joined our team.

In the summer break of 2014 we wanted to decide how our wheelchair should climb stairs.We had several concepts, which we narrowed down to two options:

A wheelchair with big wheels. The bigger the wheels the more the stairs become like a ramp. A support arm makes sure the chair is always in a safe position and can not fall down.

Bild1

The second idea was to put four rubber tracks on the side of the wheelchair. The rubber tracks should be tilted down to climb stairs and move up to drive around.

Bild2

 

The problem with the idea with big wheels was that this is not very comfortable and secure. On the other hand the rubber tracks are very heavy and the system would be very complex. So we decided to take the best of both worlds.

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Website

Hi there

We just had fun setting up this website. Hope you enjoy reading about our Project.

Here you are able to know everything about scalevo since we are updating this website every week with new content. If you are from the press, you should visit our press corner, there you can also contact us and get some material for your work.

If you are interested in helping us achieving our goal, give us a call :)