A user friendly interface to control any osc or midi enabled interface with your Twiz.
The Twiz are wireless motion sensors sending data using Bluetooth Low energy.
Their IMU (Inertial Measurement Unit) has 9 degrees of freedom and their sensor fusion (3D accelerometer + 3D gyroscope + 3D magnetometer) is made on board.
The fusion result is sent as Euler angles, telling how it is tilted compared to the gravity vector and how it is oriented compared to the north pole.
Example on ubuntu:
sudo add-apt-repository ppa:kivy-team/kivy-daily # nightly build sudo apt-get update sudo apt-get install python-kivy
git clone git://github.com/kivy/kivy.git cd kivy make python setup.py install --user # optional: cd .. && rm -rf kivy
sudo apt-get install bluez libbluetooth-dev pip install --user pybluez # apparently needed in Linux Mint
rtmidi2 (optional, not used currently):
sudo apt-get install python-pip libasound2-dev sudo pip install rtmidi2
assimp is a library for loading/rendering 3d models, installing it can make the 3d visualisation slightly better, but the visualisation should be fine without it.
sudo apt-get install cmake git clone https://github.com/assimp/assimp cd assimp cmake -G 'Unix Makefiles' make sudo cp **/libassimp.so /usr/local/lib cd port/PyAssimp python setup.py install --user
But the access to the BLE dongle might need sudo:
sudo python main.py
...and if the 3d cube blinks, using optirun might fix the problem on certain graphic cards:
sudo optirun python main.py # more here: wiki.ubuntu.com/Bumblebee
The data received is as follow:
* 3D accelerometer values * 3D Euler angles (fusion of gyroscope and magnetometer)
These values are advertised in the manufacturer data packet as 12 bytes representing 6 signed integers, each of them being normalized on 16 bits:
* Order of the data: 0011 2233 4455 AABB CCDD EEFF x y z yaw pitch roll [accel values] [euler angles] * accel values range: [-2.0 g ; +2.0 g[ * euler angles range: [-180.0 ; +180.0[
Note: the range of a 16 signed bit value is [-2^15 ; 2^15 - 1]
1) If we look at the bytes #4 and #5, we get z = 0x4455. To get the acceleration value, the calculation is:
z_accel = 0x4455 * 4.0 / 2^16 = 17493 * 4.0 / 2^16 = 1.0677 G (Gravity, not grams ;p)
Note: When the sensor is horizontal with the battery below, z should be -1.
2) To get the yaw angle, corresponding to 0xAABB in our example:
yaw_angle = 0xAABB * 360.0 / 2^16 = -21829 * 360.0 / 2^16 = -119.9 degrees
Note: the accuracy of magnetometers is not that great yet, the fusion with the gyroscope improves it but decimals are not really relevant.