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Old May 11, 2006, 01:15 PM
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gumstix + sparkfun 6DOF IMU

I'm finally ready to get a gumstix to play with and I'm thinking about getting Sparkfun's 6DOF board to give it something to talk to. Maybe a GPS also, one of Sparkfun's or a Gumstix GPSstix.

I'm lost on the hardware side! I think I need a breakout board?? Maybe I should continue to research before I buy. I would however like to get something that I know can be made ot work, and then spen the time making it work. If I can tilt th IMU and get a servo to move, I'm golden!!

Can I do it? Should I do it?

Better IMUs in the same price range? Ones with magnetometers?
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Old May 11, 2006, 01:31 PM
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OK, the outputs of the IMU are:

* Three gyro readings
* Three tilt readings
* Three temperature readings from ADXRS sensors
* Three 2.5V outputs from the ADXRS sensors for error correction
* One battery level voltage

This thing uses Bluetooth, and Bluetooth only? Is this a bad idea?
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Old May 11, 2006, 03:08 PM
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Originally Posted by space_case
This thing uses Bluetooth, and Bluetooth only? Is this a bad idea?
Earlier, on SparkFun's old site, they had a note that said if you don't need Bluetooth on their IMU they would take it off and you'd just have serial, for a slightly lower cost. I bet they would still do this for you; they're awfully friendly to work with.

They do seem to go a bit Bluetooth-crazy sometimes... it's fine, but not really needed for all projects. I think it came in handy for their rowing device that they made a while back, and that's probably how it got on there in the first place.


Luke
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Old May 20, 2006, 05:17 AM
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On the website if you open the link you can remove the bluetooth option for a $50 saving - think im gonna order one now
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Old May 20, 2006, 07:36 AM
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Does anyone have any feedback on how well the sparkfun imu works? I haven't seen one running, but I've held one in my hands. I was a bit surprised that the z axis board was really loose. It seemed like movement within the unit itself could account for +/- 5-10 degrees in angular error. The whole thing had a less-than-solid feel. I assume a person would have to do some extra work to make sure all the bits are locked down relative to themselves so there isn't any flapping or movement within the unit. What is a little vibration going to do to it? Also, if the sensors aren't oriented exactly orthogonal to each other, there is going to have to be some sort of calibration that's done in software to get good results. I know higher end units will do this sort of calibration at the factory and compensate for assembly variation with some high end matrix mathematics. I don't want to sound too negative on the sparkfun unit here since haven't seen it running, but holding one in my hand, I'm slightly sceptical. I think you probably get what you pay for (and the sparkfun unit could be a little overpriced in my speculation.) But again, I haven't seen it actually running so I'm curious what real world results people are getting with it.
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Old May 20, 2006, 10:36 AM
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Well, I've only ordered the gumstix so far. I spoke with a guy at Sparkfun about the unit. He said he was staring at the next gen prototype and that it would be a good bit better. It will have a magnatometer included, an ARM instead of a PIC, and cost a few hundred $$ more.

OK then, what is the best route for an IMU under $1000? Roll your own? ANything else out there?
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Old May 20, 2006, 10:37 AM
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Originally Posted by clolson
I was a bit surprised that the z axis board was really loose. It seemed like movement within the unit itself could account for +/- 5-10 degrees in angular error. The whole thing had a less-than-solid feel.
This doesn't sound too good
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Old May 21, 2006, 12:33 PM
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Have you considered Phoenix from http://www.o-navi.com/products.htm (approx $1K).
It seems to have everything (6DOF, GPS, static/dynamic pressure, servo outputs, and on top of that it is a software development platform of its own). I don't know more about it, than you can read on their home page. Has anybody experience with it?
Anyway, I am working on an (ever changing) UAV autopilot project based on gumstix. So far I have reproduced the results by pascal.brisset@wanadoo.fr, and I am able to control 6 servos with a X-box controller.
(http://perso.wanadoo.fr/pascal.bris...ml#pwm_accuracy)
At present I am making a coanda flying saucer (http://jlnlabs.imars.com/gfsuav/index.htm) and control it with a X-box controller through a gumstix.
I am still looking for a sensor package. I might go for SparkFun IMU ans GPS.
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Old May 21, 2006, 02:20 PM
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Quote:
Originally Posted by hogar
Have you considered Phoenix from http://www.o-navi.com/products.htm (approx $1K).
It seems to have everything (6DOF, GPS, static/dynamic pressure, servo outputs, and on top of that it is a software development platform of its own). I don't know more about it, than you can read on their home page. Has anybody experience with it?
Anyway, I am working on an (ever changing) UAV autopilot project based on gumstix. So far I have reproduced the results by pascal.brisset@wanadoo.fr, and I am able to control 6 servos with a X-box controller.
(http://perso.wanadoo.fr/pascal.bris...ml#pwm_accuracy)
At present I am making a coanda flying saucer (http://jlnlabs.imars.com/gfsuav/index.htm) and control it with a X-box controller through a gumstix.
I am still looking for a sensor package. I might go for SparkFun IMU ans GPS.

I'm running out of serial port in the design. How many do you have?

Mine:

IMU
GPS (some interfaces use 2 ports??)
RFM
servo circuit
pressure sensors (3)
possible AOA. beta sensors

I'm still learning a lot, but I went ahead and bought the gumstix to play with.
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Old May 22, 2006, 02:23 PM
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I have a Gumstix with a STUART Waysmall. It has 2 serial RS232 and a GPIO PAD (I2C, STUART, NSSP, AC97, 4xGPIO). I use 1 GPIO to control servos (ref. design in http://perso.wanadoo.fr/pascal.bris...ml#pwm_accuracy). I count on connecting IMU and GPS to the serial ports and the rest on the GPIO's.
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Old May 22, 2006, 05:12 PM
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Quote:
Originally Posted by hogar
I have a Gumstix with a STUART Waysmall. It has 2 serial RS232 and a GPIO PAD (I2C, STUART, NSSP, AC97, 4xGPIO). I use 1 GPIO to control servos (ref. design in http://perso.wanadoo.fr/pascal.bris...ml#pwm_accuracy). I count on connecting IMU and GPS to the serial ports and the rest on the GPIO's.
Good, thanks.
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Old Jul 10, 2006, 08:05 PM
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Please welcome to join this platform, for a FULL SEC UAV Project.

Gumstix is Software Embedded Control, so its exact advance solution!

We can build this easy upgradeable UAV system together here, as an Open Source!

http://www.sourceforge.net/projects/full-uav-sec

Idea & Outline, (Module)
PXA 255 Hardware design,
Algorithms & Programming,...


Sonar Alti., Digital Compass, Expansion Interface, CAN Bus, Motor controller,-
Temperature, Servos --------------------> Gumstix -----> GPS
IMU, Pressure, Airspeed, ----> ADCís --------> Gumstix -----> Comms Radio


We look to start work allocation soon!

Nice to meet you!

Jeffrey.
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Old Jun 04, 2009, 03:26 PM
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Startup on 6DOF Atomic IMU

Being a beginner, facing some problems regarding running of 6DOF IMU and interpretting its output............here is my query
> I hv bought an 6DOFatomic imu module. i soldered the right angled headers incorrectly to the serial port and during desoldering the pad of the rx pin came out (Is there any way to get a new pad or to fix this?) . So now i'm using the Din and Dout pins on the xbee to receive data via hard wired uart(but I am not connecting XBee module). I'm also connecting the vcc and ground pins. Another imp factor is that i'm using my arduino as a ftdi board here.. so using the Rx, Tx, Gnd and Vcc pins and have managed to somehow run the atomic mixer in this manner...do anyone answer me the following questions???
>
> 1) What other pins do i need to use to receive data in proper format by this method.???
> 2) What is the use of RTS and CTS pins?? (i hv previously used a bluetooth module in a remote and had shorted those pins.. i dont know why, but it was in the instruction manual)
> 3) Is the data packet received by the xbee from the imu different than that received by the hard wired uart connection from the IMU??
> 4) Why is there so great a time lag between IMU movement and display on the mixer?
> 5) What is the exact format of the packet that i receive after taking out the signal which would otherwise go to the XBee?

Please answer the query asap.. .....
Thanx in advance...........................
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Old Jun 04, 2009, 05:51 PM
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Kirkland, WA
Joined May 2009
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Quote:
Originally Posted by clolson
Does anyone have any feedback on how well the sparkfun imu works? I haven't seen one running, but I've held one in my hands. I was a bit surprised that the z axis board was really loose. It seemed like movement within the unit itself could account for +/- 5-10 degrees in angular error. The whole thing had a less-than-solid feel. I assume a person would have to do some extra work to make sure all the bits are locked down relative to themselves so there isn't any flapping or movement within the unit. What is a little vibration going to do to it? Also, if the sensors aren't oriented exactly orthogonal to each other, there is going to have to be some sort of calibration that's done in software to get good results. I know higher end units will do this sort of calibration at the factory and compensate for assembly variation with some high end matrix mathematics. I don't want to sound too negative on the sparkfun unit here since haven't seen it running, but holding one in my hand, I'm slightly sceptical. I think you probably get what you pay for (and the sparkfun unit could be a little overpriced in my speculation.) But again, I haven't seen it actually running so I'm curious what real world results people are getting with it.
I am working on an IMU-based autopilot project with my neighbor, and we purchased the Sparkfun 6-DOF IMU (the cheap one). We were also very wary of the attachment of the vertical boards, but they are well connected and (relatively) sturdy. The sensors are noisy and can have a pretty big bias. We've got some simple gyro integration software running on it now (no compensation using gravity) and we can generate 10-20 degrees of error in a minute of hand-driven movement. You do get what you pay for.
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