Posted by Chris Anderson on September 22, 2009 at 12:36pm
At last, the long-awaited ArduIMU is available! You can buy the hardware here (the first batch sold out within minutes, but he's making more quickly). The software is in beta, and you can find it here. It is, as promised, $99, making it the first sub-$100 AHRS in the world!
Proper documentation is coming soon, but here are the highlights:
Features
-3 Axis Accelerometer
-3 Axis Gyroscopes
-Arduino Compatible (Atmega328 onboard)
-Source Code included and Open Source!
-Power LED (Green)
-Status LEDs (Red, Blue, Yellow)
-SPI port available for more sensors.
-GPS port (uBlox ready!)
-Code based on Bill Premerlani's Direction Cosine Matrix
This is actually considered a full Attitude Heading Reference System, because it is IMU hardware plus the software to interpret the sensor readings and convert them into absolute attitude and heading information. The output is a serial ASCII string with raw sensor values and the DCM matrix values. You would use this with an autopilot board to convert those matrix values into commands for the your control surfaces.
The board works without the GPS module, but in that case the yaw readings are unreliable. If you add the GPS, the yaw is corrected. We will be releasing a magnetometer module to do the same thing indoors.
The following should be taken as constructive rather than purely critical, but why the whole solder-together deal on the IMU board...why not just use an Invensense IME3000 3 axis accelerometer, an IDG500 (the IDG 300 is being EOLd) and an IXZ500 [or if cheaper an equivalent set of STMicro sensors]- you could have a nice clean flat package, and could have made it a shield and added the Freescale airspeed sensor - a lower cost and hopefully better result package than using the current shield and the XYZ Thermopiles. - I guess what I am really asking is...besides cost, what were the driving factors of this board design? Additionally, if you did create this solution, and the corresponding software - you would have a drop-in solution to replace the current thermopile based shield (and obviously a built in user base of people to upgrade.)
Just to check, you meant 50Hz not 50MHz for DCM update rate. Did you arrive at that refresh rate to be compatible with the radio/servo PCM refresh rates or is that limited by the processing power you have available for the DCM calculations?
Also, if one wanted to adapt the ArduIMU to work with the current autopilot, one key question is whether the IMU requires GPS data in its calculation of attitude...my impression from the postings from Bill Premerlani was that his code uses the GPS heading data to update/correct the gyro/accel data.
I was afraid of that. I dont think the XYZ sensors will work where i live. too many mountains. guess i need to wait till ardumega, and find a use for my current ardupilot board.
Yes, that could be done, but we're focused on Ardupilot Mega, which will be designed from the ground up to use this. If the community wants to adapt the current Ardupilot code to use the IMU, that would be great, but it's not our priority at the moment.
Looks great, but I will await the ArduMega. I have no desire to move platforms until that ones comes out. Its great that we have an IMU - but 2 boards in the aircraft is a little much for my platforms.
@Bill P & Jordi.
Will there be a guide on integrating this IMU into the current Ardupilot and changing the code as TCIII says to get it to use the IMU over the shield and the XYZ sensors ?
Essentially you could remove the GPS from the Shield board, plug it into the ArduIMU, take the serial output of the ArduIMU and input it into the Ardupilot Rx input where the GPS used to go and remove the XY and Z sensors from the Shield board. Rewite the Ardupilot code to use the ArduIMU input to stabilize and guide the aircraft instead of the XY and Z sensors. This sounds like a description of the Ardupilot Mega.
This looks like a nice piece of kit. I have been looking at buying an reasonably priced autopilot far awhile now but the lack of z-sensors put me off. Will the board be distributed by any UK dealers like Cool Components (who supply the Ardupilot board?
I assume that the Ardupilot software will need to be re-written to take advantage of the new sensors
Comments
Again, just curious what the parameters were.
Just to check, you meant 50Hz not 50MHz for DCM update rate. Did you arrive at that refresh rate to be compatible with the radio/servo PCM refresh rates or is that limited by the processing power you have available for the DCM calculations?
Also, if one wanted to adapt the ArduIMU to work with the current autopilot, one key question is whether the IMU requires GPS data in its calculation of attitude...my impression from the postings from Bill Premerlani was that his code uses the GPS heading data to update/correct the gyro/accel data.
Thanks,
Dave
Like you, I am going to wait for the Ardupilot Mega. It will be nice not to have IR sensors plastered around the fuse!
Regards,
TCIII
Yes, that could be done, but we're focused on Ardupilot Mega, which will be designed from the ground up to use this. If the community wants to adapt the current Ardupilot code to use the IMU, that would be great, but it's not our priority at the moment.
@Bill P & Jordi.
Will there be a guide on integrating this IMU into the current Ardupilot and changing the code as TCIII says to get it to use the IMU over the shield and the XYZ sensors ?
Essentially you could remove the GPS from the Shield board, plug it into the ArduIMU, take the serial output of the ArduIMU and input it into the Ardupilot Rx input where the GPS used to go and remove the XY and Z sensors from the Shield board. Rewite the Ardupilot code to use the ArduIMU input to stabilize and guide the aircraft instead of the XY and Z sensors. This sounds like a description of the Ardupilot Mega.
Just a thought.
Regards,
TCIII
I assume that the Ardupilot software will need to be re-written to take advantage of the new sensors
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