My new AHRS!
Hey everyone. I'm just finishing up a new AHRS design (see picture below). The sensors it uses are almost exactly equivalent to the Razor from Sparkfun, but I added a nice 3.3V regulator and a STM32 processor running at 72 Mhz. The faster processor makes it easier to run a good filter.
The unit uses an Extended Kalman Filter for yaw, pitch, and roll estimation. It doesn't do centripetal compensation, but I routed out an extra UART and an SPI bus for anyone who wants to add extra sensors. I was thinking specifically about GPS when I selected the on-board regulator - it can supply up to 400 mA of current, which should be enough to power whatever GPS unit you wanted to throw at it. The firmware is open-source.
The unit uses an Extended Kalman Filter for yaw, pitch, and roll estimation. It doesn't do centripetal compensation, but I routed out an extra UART and an SPI bus for anyone who wants to add extra sensors. I was thinking specifically about GPS when I selected the on-board regulator - it can supply up to 400 mA of current, which should be enough to power whatever GPS unit you wanted to throw at it. The firmware is open-source.
I'll be selling them from my website by the end of the month: http://www.chrobotics.com. If you want one, contact me directly and mention that you are a member of DIY Drones - I'll drop the price for you. :-)
Replies to This Discussion
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Permalink Reply by Caleb Chamberlain on -
@Michael
Yeah the STM32 is a nice MCU. There is a new LPC chip from Phillips that also uses the ARM Cortex core, but it can be clocked up to 100 Mhz. I might look into that one for future projects.
As far as a roadmap goes... I'll be releasing a wide variety of sensors, from inertial sensors, to optic flow, to laser ranging, etc. I have a few more designs in the pipeline. I don't think that I'll develop a full autopilot, at least not to sell.
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Permalink Reply by Jonathan Lussier on -
Nice! It's a bit what I'm aiming at doing as well, same processor but I will be trying to make it as cheap, small, and light as possible, with very cheap gyro and accel/magnetometer. Hoping the kalman filter can compensate for the cheap sensors ;)
Keep up the good work!
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Permalink Reply by Patricio on -
Caleb, A little bit offtoice but, i am working on my IMU disign and i am having some trouble to find Eagle Libraries/footprints for the STM32F103T or STM32F103C, do you have them? If so could you share them with me? Thanks!
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