FreeIMU / FreeFlight IMU / 9 DOF sensor stick etc.

[Doron]

Fabio

I have been following a few posts on the group about several IMU's . (so many... i don't have the time to read all...)

Please help me sort this out :

1) How is FreeIMU different/better then the Sparkfun 9 degrees sensor stickfor $99.95 (other then LLC ?)

2) How is it different/better then the Freeflight IMU for $??.??

3) When will you be able to sell it?

4) What is the price of your IMU (ready to fly) delivered to US ?


Thanks.

-Doron.

[JussiH]

Hi Doron

The main difference is in the sensor choice

FreeFlight IMU uses ITG3200 gyrom BMA180 Accel and HMC5883L magnetometer. In addition to these there is also a BMP085 pressure sensor!

9DOF stick uses ITG3200, ADX345 and HMC5843.

They will probably be available soon! Prices are not set yet, but it will be able to compete very well with Sparkfun 9DOF stick!

[fax8]

> 1) How is FreeIMU different/better then the Sparkfun 9 degrees sensor
> stickfor $99.95 (other then LLC ?)

The sensors are the same.

The differences are:
FreeIMU is a true libre hardware project: released under CC-BY-SA and designed with a libre PCB design software. On the project page you find all the info to build your own FreeIMU.

FreeIMU breaks out accel and gyro interrupt pins for interrupt based reading of the sensors.

FreeIMU has solder jumpers for configuring the addresses of the accelerometer and the gyroscope, so that you can have 2 accelerometers and 2 gyroscopes on the same I2C bus (not really useful on a quad but nice to have on other applications: eg: human movement tracking)

FreeIMU v0.2 integrates a LLC and all the pullups so the connections are very simple (see thevideo).

Each FreeIMU comes fully tested by me (many Sparkfun boards have some non functioning sensors resulting in issues for the users).

FreeIMU comes with an easy to use orientation sensing library ready to be implemented in your project.

2) How is it different/better then the Freeflight IMU for $??.??

FreeIMU is a true libre hardware, FreeFlight IMU is not (designed with a non libre PCB editing software, released under a licence which won't allow you selling your free flight imu clones and derivatives).

LLC integrated in FreeIMU v0.2

FreeIMU uses the ADXL345 instead of the BMA180

no pressure sensor in FreeIMU

FreeIMU is ROHS compatible. PCBs have been produced in the USA while the building process is hand made by myself here in Italy using lead free solder paste.
I know that past prototypes of FFIMU have been produced in China. Don't know where they plan to mass produce them.

Don't know the selling price of FreeFlight IMU nor if it will be available in the short term. As they are planning for mass production they'll probably have a more competitive price as soon as they goes out of prototyping. With FreeIMU, I'm not interested in keeping the prices low but rather make it a fast evolving project produced in very small batches to fastly adapt to new sensors ,technologies and users need. I already have version 0.3 with the ADXL346 and HMC5883 designed and ready for production as well as a breakout board for the MPU6050 which I'll test asap and evaluate for inclusion in FreeIMU on future versions.

3) When will you be able to sell it?

Next batch end of next week.

4) What is the price of your IMU (ready to fly) delivered to US ?

There is a fixed price for FreeIMU prototypes:
70 euro FreeIMU v0.1
75 euro FreeIMU v0.2

Prices include shipping (but as you are in the USA expect a 2 to 3 weeks shipping time or pay the additional costs for a better shipping option).

As you live in the USA, I would suggest you to have FreeIMU PCB built with Dorkbot PDX, buy the sensors and components as per the BOM file (http://www.varesano.net/files/FreeIMU_factory.csv) and reflow solder it by yourself.

Gerbers, KiCAD sources and everything you need to build your own FreeIMU at http://www.varesano.net/projects/hardware/FreeIMU


Hope this helps. If you have other questions I'm here.

Fabio Varesano

[Doron]

This is very exciting development ! ! !

I am curious how well they perform in the 'real-world'... with Temperature gradients, power supply noise, motor(s) noise, RF-noise and mostly ... the dreaded LF/HF vibrations

Does anyone know if there are any such controlled tests ? (identical airframe, different IMU's (also different control logic)

-Doron.

[fax8]

I'm not aware of any of such tests.