Our brainstorming was very intensive. We examined various factors, especially the items “Good” vs. “Evil”. We associated night, fear and attack with “Evil”. Why we chose a teddy bear is very easy to describe. During our whole brainstorming we always recollected to the teddy bear. It never turns out of our minds. It is the typical toy of everyone’s childhood. Everybody has a relationship to his teddy. It is a typical companion, so we decided to apply our teddy associations as the “Good” aspect for the project.
We thought about situations where we would like to have a special friend with us. Sometimes when it is very late and you have to go home alone you feel very uncomfortable. An attender would be perfect in such a situation. In the case an attacker follows you or attacks you, your friend the teddy bear includes some rescue levels. Possible features would be an included pepperspray, barking sound, police sound, blue light effects or an emergency call to the police.
Our concept is a teddy bear, not too big, which fits in every handbag to carry it with you. We decided to integrate three rescue levels depending on the degree of danger. When you are going home alone in the night and you feel uncomfortable or you are imagining that someone is following you, the first level of the Rescute can be activated. Immediately the bear starts to bark. Thus, the follower will notice you are not alone, he will think you have a dog with you, not knowing that there is far more in your bag. Perhaps the follower is already warned and goes away. If not, you can select the second level. The bear starts to shake his head and its eyes begin to flash in blue. Additionally, there comes police sound out of its body. The bear simulates the police arriving. If this is not discouraging the attacker or he starts attacking you you can select the third and last level of Rescute, the Pepper spray with light effects. This will help you to target perfectly at the aggressors eyes. The third level will give you enough time to run away or to get help.
How does it work?
First of all, we thought about the connective of our bear, the basis of our levels. Therefore, we remembered of the toys which have an integrated music box, controllable by a trigger line. We want to use this principle for our project. We used a pipe with copper tape. For each level we put two piece of copper tape inside the pipe which are separated from each other. These tapes will be connected by steel wool which connects the two copper tape sides. The wool hangs on a line. This line could be applied by lift pass holder which is fixed on the inner bottom of the bear. It closes the circuit and the effects will be triggered. When someone pulls the line the wool connects two of the tapes and releases the connective effect.
For the sound effects we used a greeting card sound modul. We tried to build an audio amplifier to multiply the sound but this was not easy. So we put a pipe above the original loud speaker. This improved the volume of the sound with a great difference.
For the blue eyes we bought white lamps and painted them blue. The shaking head is a servo which is fixed between the shoulders of the bear. The moving part is fixed with plexiglass and hot glue at the head.
The pepperspray is integrated by a hacked airwick. This airwick starts to spray by getting an electric impulse via piezo ignition. We controlled this impulse by one pin of the arduino. For the audience at the presentation we did not use a pepperspray but a airwick spray.
For the light effect of the spray we used three red lamps and three white lamps connected by a transistor with two parallel circuits, one for white light, one for red light. For those lights the arduino energy was not enough. Thus, we used a 9 V power plug.
Pins already contain electrical charge:
To connect our pipe circuit to the arduino, we wanted to read the digital pin. While we uploaded the signal via serial, we discovered that the pins already contained a electrical charge although the circuit was not yet closed. To circumvent this problem we attached groundings by resistors. These connect the pins with ground. So the right signal was read by serial.
Find a right transistor:
For the light effect of the pepperspray we needed a transistor circuit. The circuit was easy to build but to find the right transistor not. Transistors and voltage regulators look very similar, so our first trials failed because we used no transistor. After we found the “real” transistor we had to decide which transistor type we need. Which number is for which voltage and which type (npn, pnp) is appropriate for our circuit. So for the usage of transistors, you have to read a lot of data sheets and documentations about transistors. As the right transistor was found, we discovered that all transistors differ in their allocation of emitter, collector and base. So we had to read more data sheets and we learned to like them.
The next problem is also concerned with the light effect of the pepperspray: Our led chain did not react on input from the Arduino pin. The leds were glowing all the time, also without power of the arduino. Different voltages caused this problem. 5 V of the Arduino USB port are not similar to the 5 V of the power supply. This could be corrected by equipotential. Now the Arduino has only one power source: power plug, which is directly connected to arduino.
Experiment to construct an amplifier:
The greeting card sound modules were very quite. So we wanted to construct a amplifier. We found a simple circuit diagram and started to construct.
Because we did not have the named transistor, we used another. Indeed, the bigger speaker was able to make some noise, unfortunately not our recorded barking and siren sound. Because time was precious, we decided to take the physical way. A pipe should amplify the volume. This worked great.
In spite of correct circuite and correct code we had problems to activate the sound modules with the arduino pins. We checked all contacts with the multimeter and could not find any leak.
Our problem was that we used only one speaker for two music modules. So the 5 V power of the arduino was divided in two parts. The power from source went back over the ground connection from the other sound module without activating the speaker. So each module had only 2.5 V, insufficient power to play back sounds.
The problem could be resolved by usage of a second speaker.
Steel wool in pipe circulation:
The steel wool on the line damaged several times the copper tape and the solder joint. So we lost the contact to the Arduino pin and the whole prototype did not work anymore. We had to exchange the circuit several times.
For presentation we wrapped the steel wool loosely with more copper tape, so that is more softer than the steel wool but as flexible. This is no perfect solution, but we could present our prototype without problems.
If we would have had more time to strengthen Rescute, we would like to test more variants for the pipe circuit instead of the steel wool. Perhaps something more smooth with less attrition.
Moreover we would like to use a better sound module with amplifier for the barking and siren sound. So that it sounds more realistic.
If our implementation of our concept is perfect without failures, we would beef up the concept with a fourth rescue level. While the fourth level is triggered, Rescute shall send automatically an emergency call. Maybe this could be implemented by a bluetooth connection to the smartphone, which afterwards dials automatically the 112.
Unfortunately the week is over and we have no time left to extend Rescute.