Getting calclated values from mpu 9150

Question

for a school project we got a mpu 9150 (Gyro/Accelerometer/Magnetometer(?)) and we want to get Roll/Pitch/Yaw/Heading for it.

I used a code that was as an example in the libary, but it gives us only the raw datas in that format: ax/ay/az/gx/gy/gz/mx/my/mz. Thats not what we want.

I managed to get roll and pitch so far with the following snippet:

roll = atan2(ay, az)+PI;
pitch = atan2(-ax, az)+PI;

// Convert everything from radians to degrees:
pitch *= 180.0 / PI;
roll  *= 180.0 / PI;

And i read that i have to use the magnetometer to get the yaw, but i have no idea what formular i need for it.

In the example code there is also this snippet inside, maybe thats all i need to use or anyone knows other functions/methods i could use?

// read raw accel/gyro measurements from device
accelgyro.getMotion9(&ax, &ay, &az, &gx, &gy, &gz, &mx, &my, &mz);

// these methods (and a few others) are also available
//accelgyro.getAcceleration(&ax, &ay, &az);
//accelgyro.getRotation(&gx, &gy, &gz);

I working with the I2Cdev and MPU6050 libaries

Another question would be, what kind of things can i get from the sensor else? Is it possible to get the height or difference in height of it?

Thanks for help.

Answer 1

Raw values of your mpu are mostly very inexact, drifting away, ... not really usable. The MPU6050 libary is very useful to get useful values. To get your yaw/roll/pitch you could use the MPU6050 Libary like the example described in this example sketch . Just add

#define OUTPUT_READABLE_YAWPITCHROLL

on top this code an run it (with the right baudrate).

With your sensor it´s also possible to get the actual temperature.