Super Short Distance Vehicle

In the last few days I had the privilege to participate at the amazing Science Hack Day Berlin!

It was the first time for me. I just went there and listened to the speeches of some people who wanted to invent something more or less related to science. It was full of talented and crazy people! A very nice atmosphere and an unforgettable event, thanks to the beautiful staff !

The rules were: you have less than 48h time to build/hack something related to science. I didn’t know those rules. I arrived late and I heard Peter Westerhoff‘s pitch (never met before). He needed someone to help him with the electronic part of his idea: the Super Short Distance Vehicle.

Do you really know what kind of transportation do you need if you daily commute to your job by public transport? No, you don’t!

You need something that’s fast, light, with maximum 10-15 km of range. You need the SSDV! (If you are not sure about this, you can ask Peter, he will surely convince you).

I and Peter, my German alter ego, discussing the next improvements

The basic idea was to add a lithium battery pack and a brushless motor to a standard kickboard. It was more complicated than we thought! We installed a 300W 7.7V brushless motor, used for trucks models. These guys are really powerful but they run really fast! We opted for a belt transmission, with a gear ratio of some 30:1, reaching a maximum (safe) theoretical speed of 12km/h. In order to achieve this, we asked the patient staff to print something: a reduction gear and a plate to keep the belt on the rear wheel of the kickboard.

3D printing of the gear

The motor needs to be controlled by a dedicated controller. We also needed to set the speed with a special servo tester, also coming from the models world. It’s basically a pulse generator that tells the controller how fast should turn the motor. We add a smiling safety footswitch on the kickboard: if you want to move, you have to press it with your foot. If you jump off the board, the motor will stop.

Smiling footswitch

It’s a common dual SPDT switch used for home lighting. We have engineered it by adding an additional spring so that it goes back to the “open” position, and we connected the two switches together with a small wood board. The switches open the circuits of two of the three phases of the brushless motor. We also needed to tweak it a little to fit the generous wiring of the motor (must be capable of delivering almost 40A!)

Tweaked switch

We put a 5.000 mAh battery pack just under the board. That should provide sufficient autonomy to go to the train station and from there to work!

The question is… Is it working? The answer is in the video below!

Yep, maybe we still need some tuning… but DAMN, that’s a SSDV!!!

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