Best title I could come up with...
What I wanted to do:
gather, record and display information of my motorcycle about:
- acceleration (xyz)
- rotation/tilted position (xy)
- gps data
Gps data was omitted early on on for the lack of space for a gps antenna and the chip.
I chose the Rasperry Pi zero w to record and transmit the data, because it has wlan/bluetooth, persistant storage, an os capable of things like ftp, ssh or python and I was familiar with it. For this task, the raspi zero w is vastly overpowered. Basically I just want I2C connections for sensor data and displays, minimal storage (talking about KB here not MB) and some sort of connecting, preferably wireless. There are a lot of end consumer chips out there which fit the bill, however I went with what I know and what can be used later for a variety other things. Write me if you know a chipset, which is suitable.
I can watch 720p movies on the rasp w zero, but the power consumption is too much if I just want record sensor data.
Which means that the power supply needs to be bigger. I bought a cell phone external battery and took it apart. Soldered a micro usb to it and pluggled it in the raspi. Disabled all services on raspian (only command login, ssh and python) and got about ~ 5 hours of runtime. Battery capacity 1600 mah. That lasts. I can't do more than 3 hours on my yamaha without out a break. usually its in the alps and inbetween there are places where you want to stop.
The design revolved around fitting the raspi, battery, sensor, display and finding a place at the bike to attach it. The only place in view for the display is in the middle of the handlebar.
As you can see in the pictures, it is one unit containing every thing, which is just held by a 5mm counterpart. The rod has 32mm and the counterpart is 5mm thick and 10 wide. I didn't do any strenth calculations... the PLA I used in those dimensions, showed no signs of deformation after speeds of more than 200kph and vibration of 13000 rpm (~216 hz).
Basically you just need to find awawy to position everything around a rod, so that the display is visible, the on and off switch is accesible and the wiring inside has room.
It turned out that I'm rather untalented in soldering, so I got the raspi with pins, where you just need to plug in. On the other end, the display, battery, button, switch and accelerometer it had to be soldered. I did my best, which holds so far.
The housing designs and the components worked together as intended, however the accelerometer wasn't able to handle vibrations from the engine. It worked fine up until about 3000 rpm, at 5000 rpm the sensor only put out disturbances. I tried to use the build in low pass filter and use adaptive exponential smoothing algorithms on the data, but in the end, there was nothing conclusiv to be gathered.
Please write me if you have knowlege about accelerometer/position sensor. I wrapped the sensor in foam, I wrapped the connection to the rod in foam. Unfortunately it was not enough to dampen the vibrations.
I want to replace the raspi with a slimmer chip, find a sensor which can handle vibrations and add gps. Write me your ideas!