Blog - Sketching with Hardware

Detailed Description of the Project “Ein Münchner zwischen Himmel und Erde” (A „Munich’er“ between Heaven and Earth)

Published on: | Author: Barbara Maria Elisabeth Schindler | Categories: 2016b

Day 1 – Concept Phase

Scavenger hunt – that was the topic this time to which we should consider an object that could be used outdoor and includes a physical puzzle, which should be solved by the user to get a hint to the next object.

So as we were going outside for brainstorming, Katrin and I thought of games, which we were playing as children at the schoolyard. So french elastic came into our mind, but we saw the biggest problem in the two motors at both ends, which had to be strong enough for swinging the ropes. Also we had the idea of combining skipping as an interaction with putting up an umbrella, which should protect something like a candle from the wind or the rain.

But what appealed to us at most was the game called HOPSCOTCH (in German: Himmel und Hölle): there you have to hop into one numbered field after the other according to rules from which numerous versions exist. For our technical version, we decided on a base area on which all seven rectangular board and one semi circular one stand.

These fields should also have holes, which should be illuminated by bordering LEDs when somebody has jumped on it. First, we wanted for each hole one LED, so in total about 100 LEDs, but because of this we could had have problems with finding a power supply that would deliver enough ampere and with the wires which had to be thick enough for this high amperage. So we had to consider another solution: our idea was to place a reflecting surface on the base area under each board and to fix underside of each board a milky foil, which refracts the reflecting light, so that only four LEDs per board, in case of the semi circular field six LEDs, are necessary.

For determining if the user has jumped on the right field, we consider to attach something which consists of conductive material to the bottom side of each field and to the base area so if both are in direct contact, we can read this in the program running on the Arduino. In case for the base area, our choice fell on aluminium foil because on the one hand it can conduct electricity and on the other hand it has a specular surface which was perfect to reflect the light coming from the LEDs. For the boards, we thought that steel wool would be ideal because apart from the fact that it is very cheap it has a relatively big conductive surface like a ball so if the board is pushed down, the steel wool and the aluminium foil are getting easily in touch.

ConceptHopscrotch ConceptBoards

But the next question we were faced up with was how the board can be pushed down cushioned and get up autonomous? Our first concept includes springs but these would be too expensive and not easily to fix. So these yellow cleaning sponges, which are normally used in the kitchen, came into our minds. Besides they also aren’t expensive and available in many shops, they can easily be compressed when the user is hopping on the field and get autonomously back in their original shape afterwards again.


Another problem we found out at the first day was the thickness of the boards. As you can see on the picture, the boards we were just standing, not even jumping on it, sagged very fast. But because in the factory there was no wood that could be suitable for our purposes we decided to drive to a DIY market the next day.


Day 2 and 3 – The Realization Phase

In the DIY market, for the boards our choice fell on a type of wood which is thick and strong enough so that an adult person could jump on it without that it can breaks and which is also light enough so that the sponges can’t be pressed together by the board just because of its weight. To save time, we let the wood tailored there to the seven boards with a particular size of 38x33cm and a board of the size of 78x33cm for the semi circular area.


For the subsurface we decided on a low priced and thin species of wood and a size of round about 280x112cm so that all boards can be placed on it and on the sides there is enough safety space when the user fell of the board for example. But because this subsurface was too big for transporting it with the car, we let it tailored into four boards with a size of round about 112x70cm.

Arrived at the factory, we were placing all boards on this subsurface and realized that three of these four underground boards were enough: our plan was to position on the first area the boards 1 and 2, on the second area the boards 3, 4 and 5 and on the third the boards 6, 7 and 8 with a space of 2cm between the boards. And an advantage that implies this was that now our game can be divided into three parts for an easier transport and more space-saving storage.

Also we have planned how the four/six LEDs on each board could be placed at best and how long the wires between them have to be. After cutting the wires and removing the insulation, we soldered the wires at the LEDs of each board.

Also we drilled 4×4 holes per board and 8, 6, 4 and 2 respectively for the last board and fixed underside each board the milky foil, whereby at first we fixed underside on each hole a little rectangle of the same foil with the non-sticky side upturned so that the sticky side couldn’t shine through the holes and get dirty.

DrillingHoles DrillingHoles2

BoardMilkyFoil1 BoardMilkyFoil2

The sponges we cutted in half and fixed little wooden boards on it, which should act as spacers between the LEDs and the subsurface so when somebody has hopped on a board, the LEDs don’t get destroyed. Also we sprayed them with white colour so that they would reflect the light coming from the LEDs. But we hadn’t considered on a characteristic of sponges: they imbibe liquids. And because of this fact, they imbibe almost the whole white colour and so it didn’t function really well.

Sponges1 Sponges2


Day 4 – The Extra Day

Because we had spent the half Thursday at the DIY market, we decided also to utilize some hours of the Sunday at the factory.

The wires were soldered at the LEDs BETWEEN the boards and fixed the LEDs on the boards. Also we wrapped the steel wools with some aluminium foil so that strands of the wool can’t touch the aluminium foil on the subsurface unintentionally and main conductive, fixed on each wrapped steel wool a little copper tape, on which we soldered one wire per board and stuck these wools on the middle of each board with hot-melt adhesive. The sponges we stuck with the wood side on the boards at their corners and with double-sided adhesive tape we fixed the eight aluminium foil areas on the boards of the subsurface.

SteelWool FixingLEDs SubsurfaceBoard


Day 5 and 6 – The Completion and Code Phase

FinalPrototype UnderTheBoard

The last two days, we were busy with finishing our project and writing the program code.

So besides designing the subsurface we fixed the sponges of the boards on the areas of aluminium foil again with with hot-melt adhesive and planned the concept for the wiring.


At first, our concept, which you can see at the picture, was to use plug connectors for each subsurface board so that these boards could have easily been transported and stored space-saving and also the wires could have been continued by plugging these connectors. The problem was that these connectors weren’t available at Monday and so we had to find another wiring concept. As you can see on the schematics, the wires coming from the steel wools and the LED-DataInput are plugged directly to the correspondent pins of the Arduino. Of the aluminium foil-areas and the LED, the Ground-wires converge to the Ground of the power supply, to whose positive terminal the positive wire from the LED is connected and which has to provide 5V and round about 2A because of the type and the count of the LEDs.

SchematicAluminiumFoilsSteelWools SchematicLEDs CompleteSchematic

In our program code, each aluminium foil area has been assigned to one of the digital pins, which function as Inputs and from which a HIGH-signal is coming out. So if the user has jumped on a board and the aluminium and the steel wool are in contact, the power can discharge through the ground-wire and the signal read by the digital pin is LOW. Also assigned to a pin has been the Data Input of the first LED of the strip, for whose activation piloting we have used the Neopixel-Library of Adafruit. We implemented three increasingly different levels, which the user has to complete to get the hint to the object of the next team. Before the beginning of each level, the LEDs of the first board are pulsing in white and if the user pushes it down, the choreography, which has to be hopped, is shown. Then a LED-countdown runs and the user has to start. When a wrong board or not only the right board is pushed down, all LEDs pulse in red and the same level has to be jumped again. Closing, the LEDs illuminate to the direction of the next project if the last level and so our game is done.

If you are interested in our program code, you can look here.


The Story of “Der Münchner im Himmel” (The „Munich’er“ in Heaven)

As we thought about the phrase “Himmel und Hölle” (in English: “Heaven and Hell”), in our mind the well-known story of “Der Münchner im Himmel” (The “Munich’er” in Heaven”) of Ludwig Thoma came into our mind, in which the “Munich’er” Aloisius came in the heaven, but he doesn’t feel very comfortable there and so he is sent by God for some days the week back to Munich, which is the heaven for Aloisius. And because we found that this story would match to our game, we designed the subsurface with sprays like, besides clouds in the heaven, the “Hofbräuhaus”, glasses of beer and important buildings of munich like the “Frauenkirche” and the “Olympiaturm”. Also this story offers us the option for the choreography of the last level, which the user has to keep in mind and jump the way “upwards” to the heaven and then the way back to Munich, the other “heaven”. And so the user is jumping as “ein Münchner zwischen Himmel und Erde” (a “Munich’er” between Heaven and Earth).


linked categories 2016b


Write a comment