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arduIMU better than Thermopiles?

Posted by BriFly on July 10, 2010 at 7:59pm

I wanted to get peoples opinions on this.  Last week, before my ArduPilot/thermopile setup went wacky on me (servos were going crazy for no reason) I was somewhat impressed by how the thermopiles kept my airframe on a good heading and at somewhat consistent altitude.  After experiencing problems with it I decided to "upgrade" to the IMU.  I got everything hooked up and it tested well on the ground.  Today I tested it in the air and was disappointed by the results:

 

1) The system seemed to have very inconsistent airspeeds fluctuating from no throttle to full throttle on a consistent basis (no, i wasn't using an airspeed sensor....would this help?).

 

2) The altitude fluctuated so severly as compared to the thermopile setup.

 

3) The straight line travel between waypoints was very wavy and I was hard pressed to see it even do a straight line.  The thermopile setup seemed to go between waypoints pretty good in a straight line.

 

4) I initially setup the ArduPilot to steer using the enlarged rudder.  During every turn it seemed to lose altitude.  The thermopile setup used ailerons and seemed to have no issues with altitude loss in turns.  After seeing this I switched connections around so that the IMU setup would use ailerons.  But everytime I went above half throttle on the ground (and in the air) the ailerons extended to their extreme limits for no reason.  Why would it do that?

 

As far as code and such I tried the setups using 2.6.1 and 2.6.2 with the same results.  Any suggestions or hints on any of these items? 

Thanks!

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Replies

  • Moderator
    John Church July 11, 2010 at 1:01pm
    Meh- I wouldn't worry about the hardware being capable. All props to Jordi and the rest involved in hardware, but the hardware is useless without the software. I am confident that, with the right tuning/customizing (this is DIY), this hardware will fly your machine with the accuracy found in other models. And, maybe even better than other models, due to the open nature of the project.
  • Developer
    John Arne Birkeland July 11, 2010 at 10:59am
    "But everytime I went above half throttle on the ground (and in the air) the ailerons extended to their extreme limits for no reason. Why would it do that?"

    To much vibrations will do that because the sensors get over saturated. Try balancing the propeller.
    But yes, I have mixed feeling about the performance of the IMU my self also. I guess we have to keep in mind it is a $99 piece of hardware. Most IMU's cost hundreds if not thousands of dollars.
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