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Prototyping

At the beginning of the project. When I had my initial concept. I started to think about ways to realise the product. To aid me in this I got together a focus group. The focus group and I then sat down and came up with some that would fit the my concept. A few of these ideas were:

Once we had a list of these ideas we began to whittle them down until we had a handful of the best ideas left. With each of the stronger ideas I began to think about, and sketch ways in which they could be realized.

After thinking through the designs, and motions, I decided to go with the interactive coffee table design. The thing about the coffee table design that I particularly liked is that coffee tables are a common piece of living/TV room furniture. The table could easily accommodate all the electronics necessary to run the able, and still appear as an ordinary coffee table. That was a major aim of mine. To have a product that was unobtrusive to the eye, that would appear like any other coffee table, except from a few small differences.

Development of the table

For the table, the initial idea was to have a lifting bar that lifted out of the centre of the table, the lifts would be done and then the bar would be replaced in the table to return it to being a coffee table.  This however brought a few problems. One in particular was the complete lack of a sensor suitable for the job of sensing small changes in altitude, which meant I would have a problem doing it that way. So I thought about and sketched other motions and exercise methods that could be of use.

In the end I decided to use a squat/lift style of motion, show above on the left. I chose this motion because it doesn’t require much space to do, it’s simple and is an effective form of exercise. The testers said “Quite natural & organic movement”, “unusual for a table, but effective for exercise.” They also said “Simple action…rather intuitive, not a lot of explanation needed…not too strenuous.”

Other changes to the table design

After I decided on my final motion a few other issues had to be addressed. The first was that because the product was to be used as a table when not in use, a few people comment that they wouldn’t want to have to clear the table before watching TV. These comments made me adapt the lifting mechanism to make the lifting section only the surround of the table. So the centre would stay as a static surface, meaning you wouldn’t have to clear the table.

  Something a few of the participants of the individual testing commented on was the weight of the table. They said things like “wasn’t too heavy…if it was much heavier it might be too heavy”, “It’s fine for me…after a few weeks it might get too easy.” and “for adults it maybe too light, but it’s about right for teenagers” As the example of my product that will be on display at the degree show will be mostly used by adults, I decided to set the weight of the table to be suitable for the 18 – 45 age range.

So from these changes I came to the final design for the table and the mechanism for the lifting bar.

The aesthetics

I have mentioned the functional aesthetics of the table, but now I want to speak a little on the other part of the table’s aesthetics. As I said earlier, I wanted the table to look like the average coffee table that you would find in any living room. So I didn’t want it to be extravagant and flashy, because then it would be obvious and look out of place. As a result I have kept the table looking fairly simple, but still tried to make it look attractive, a table you would want to buy.

The display

An important part of the table was the way it showed the user how much time they had earned/ used. For this I wanted to keep it simple, intuitive and visual. I looked into a few ways of creating visual feedback, such as LCD display, analog gauges, and LED arrays.

 In the end I used a series of LEDs. To make it easily visible I used high brightness LEDs, and have used different coloured LEDs to differentiate between times. A numbered plaque to show which time is which will accompany the LEDs  I didn’t just want the display to be a row of LEDs , I wanted it to resemble other gauges, but still be sleek and simple. I did a few designs to see how that could be done.

Another thing that I thought was important, and so did my testers, was a display to show if you had completed a lift. Otherwise you could have done 20 lifts with only 5 counting. So I put in small display using LEDs to show when lift is completed.

Development of the electronics

The electronics in the table are a very important, and right from when I had thought of the concept for this project I had very strong ideas on what they should be.

When looking for a way to control the electronics I initially thought of using either a PicAxe or BASIC stamp chip, but Ali (Course technician, and all around legend) suggested I use the Arduino board that the earlier year were going to learn to use. The main benefits of the Arduino are that it is simple to use, has multiple input/outputs and can be used when disconnected from the computer.

The basic idea I had at the start of the project was to control the power going to the TV set, by using a relay to turn on and off the power when its sent a message from the Arduino board.

For a long time I tried to make this work. Even calling on an electronic engineer to try and make the circuit for me. In the end I decided that it was too dangerous for me to complete myself, and to much hassle to get it made for me.

The next step was then to think of a way to simulate the experience. To do this a few people suggested hacking a remote control and using it to turn the TV on and off. Doing this proved a little tricky and fiddly, but with a small solid-state relay I managed to control the remote with the Arduino.

Sensing the table lifts

 Sensing the lifting of the table has been a problem from the start of the project. Finding sensors that would suit the motion has been a difficult job. For the purposes of testing the rest of the electronics I been using a distance/proximity sensor. Although this worked well for the testing, it would probably not suit the final product because it is too easy interfered with. I went through a number of other options to find a suitable sensor, including flex/bend sensor, slide potentiometers and still didn’t find one that worked well or was readily available. So now I have decided to try and build my own sensor. A few ideas on how to do this are to make a small liquid based inclination sensor, or a plunger style sensor.

Coding

By using the Arduino board I had given myself the option of using few coding languages such as Pure Data, Max MSP, Flash, but I chose to use Arduino’s own code. I did this because it meant that I wouldn’t need to have the table connected to a computer, plus it’s a simple language that follows most basic coding principles.