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Permalink Reply by Don Cramer on July 15, 2011 at 7:27pm

Could it be that the craft is tilted slightly? If so then the lower side should generate higher rpm than the other (trying to level itself). Also, dont use trims. Reset them to zero.

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Permalink Reply by roger on July 15, 2011 at 8:06pm

On Don's note, a simple balancing your ardu on your fingers will do the trick at least in my case. What I did was put one finger approximately in the middle of the ardu arm on the left and do the same on the right. Then lift it a bit. If the ardu tilts towards you then the back part is lighter than the front part so you have to re arrange some of the item on the ardu like push back the batteries so the copter will balance out. If its the other way around, then do the appropriate shift in weight. Once you are satisfied, do the same procedure for the remaining arm pair ... hope it helps.

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Permalink Reply by Sanjaya Kumar on July 16, 2011 at 12:56pm

Make sure that the motors are exactly vertical. If one or more rotors have a non-zero thrust in the x-y plane, then two of the motors have to work extra hard to compensate for that.

I had the same problem -- I noticed on the raw-sensor radio output that two motors were consistently drawing more power and it was because my frame has booms with a round cross-section and one of the motors was tilted as a result. Correcting the tilt solved the problem.

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Permalink Reply by Marc Dantonio on July 16, 2011 at 1:06pm

@Don

I now have a bubble level to put on the vehicle at which point I will 'level' it and see what happens. I will zero trims...

@Roger

I will balance the craft but this test was done with no props and with no liftoff possible. This was simply a 1/3 throttle test and the right side motors show less thrust. This is without props as I said... It is POSSIBLE dont you think that if the gyro doesnt think its level that it might automatically call for more left side thrust? In other words, it was leveled at a non-level setting and therefore now thinks it must compensate by adding some right bank to the craft?

@Sanjaya

Thanks for answering... If I was testing with props I would say this was a possibility. Plus the craft is in no way getting airborne yet. It is simply sitting on a table and spinning up motors only to 1/3 throttle. With props installed, we require approximately 40% throttle to lift off perhaps 45% it appears.

 

I think I will try to re-level the craft using the CLI mode AFTER using the bubble level to level the APM... I will let everyone know what happens...

 

Thank you very much so far...

Marc

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Permalink Reply by Sebastian Gralla on July 16, 2011 at 1:18pm

you can recalibrate by holding sticks in disarm position for about 10 seconds (the LEDs will start flashing)

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Permalink Reply by Don Cramer on July 16, 2011 at 1:36pm

IMO, it may actually be better to slap some props on the thing and do some test hovers on a super calm day or indoors. THEN take a look at what each engine may be doing. I know in theory the motors are supposed to start all at the same time, operate at the same speed, etc.. At least in a stable hover in no wind conditions on a well balanced quad all props SHOULD be spinning the same or close rpm's..

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