Question: I have a quadcopter like the below ([source of the image)](http://www.youtube.com/watch?v=wlJn0DX9Gzw)

![here](https://i.stack.imgur.com/95Z4u.png) 

and I have an IMU (inertial measurement unit) having acc sensors in X-Y-Z and gyro sensors in X-Y-Z. Now I am trying to find an iPhone app by which I can check the values such as rotation and accelerations in each dimensions over X-Y-Z coordinates. I need to export the data in order to design a proper smoothing algorithm probably with Kalman filter or incremental filter. I noticed that the IMU needs to be calibrated because levels do not start with zero for non-moving object. For this kind of things, independent measurements with iPhone could help to adjust things.

*So how can you use iPhone to evaluate an IMU chip? Which apps? Other considerations?*

Answer: 
What are the specifications on the iPhone accelerometer? If this were something I was working on, I would start with a static 3d test to validate the imu output when it was fixed In multiple known positions. The iPhone uses a fairly cheap part, you could probably figure out what the part number is by doing some sleuthing, and then you could figure out if the iPhone is better or worse then the imu's you are looking at

(Updates 5/27/13)
From this teardown <http://www.ifixit.com/Teardown/iPhone+4+Teardown/3130/2> Apple seems to use a ST Micro proprietary part. This part ST L3G4200D (<http://www.st.com/web/catalog/sense_power/FM89/SC1288/PF250373>) is mentioned as a potentially commercially available part.

The Iphone isn't intended as an IMU, and so if I were trading off performance vs cost when designing it, I'd go for the lowest performance, cheapest part that would work.

In your case, I'd build a fixture that I could mount an IMU in, and fix it in multiple orientations so I could determine how accurate and repeatable the IMU reading were in a known, accurate position as you're taking data. Make it so that you could put in arbitrary positions and you can evaluate coupling between directions. 

I like having measurement techniques that are accurate enough to truly evaluate differences between systems. If you're using a iPhone as your reference, then you'll probably have trouble figuring out the difference between multiple sensors.
The manufacturers such as [Apple](http://www.apple.com/asia/iphone/specs.html) do not seem to publish the details about the IMU chip. The word `"teardown"` returns ambiguous material over internet about specificications of different devices but hard to judge the material. I could not find the specifications -- anyway iPhone has all kind of sensors so you can get all kind of data. The below hase some apps listed, some of them are free.

**Sensors**

```
✔ 3D Accelerometer: X, Y, Z acceleration

✔ 3D Magnetometer and Compass

✔ Integrated Accelerometer and Gyro data

✔ Location and GPS: longitude, altitude, speed 

✔ Proximity Sensor

✔ Misc: mic level, capacitive touch, battery, light-sensor

```

**Apps**

1. [most sensors] <https://itunes.apple.com/us/app/sensor-monitor/id381075251?mt=8>
2. [accelemeter] <https://itunes.apple.com/en/app/accelerometer-data-pro/id308757921?mt=8>
3. [all sensors] <https://itunes.apple.com/us/app/sensor-data/id397619802?mt=8>