Unexpected Throttle Behavior

I just loaded up 2.4 in my APM 2.5+ and went through the calibration process and set the throttle parameters and am experiencing unexpected behavior for the throttle. When in manual mode, steering works as expected, albeit courser resolution, but throttle does not work correctly. When moving the stick forward, it jitters the wheels but does not move it. When moving the stick backwards for reverse, it only has one speed, fast. It didn't matter that I reversed the channel on the radio or MP, the behavior was the same. 

If it helps, I'm using a Spektrum DX8 with an Orange 6 channel receiver. I made sure the truck was properly trimmed and the ESC was properly calibrated before adding the APM. 

Any ideas? I had something similar happen last year when I tried using the APM 2560 and IMU last year using Traxxas radio gear but chalked it up to the radio. 

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  • T3

    Okay, here's an update on the problem I had. I'm pretty sure I got it figured out.

    DON'T use the 3DR power module to get power to your APM. I swapped out the motor, ESC, and receivers and none of that fixed the problem. I even changed radio systems and still had the issue. I then stuck my wattmater (Eagle Tree e-Logger) on it and found that this thing, even though it's just a brushed motor, will pull enough amps to mess things up. I shut down my e-Logger once (100A limit) when I pulled the throttle hard and stopped. I figured it could be the power module so once I removed that, it took care of the problem.

    I now power the APM from an UBEC on 5V and then use the ESC BEC to power the servo at the normal 6V from the Traxxas ESC. J1 is not installed to accommodate this dual power setup.

    Now, onto the next problem. I'll start a new thread for that.

  • Admin


    I presently have two rover setups, one using an APM1.4/Oilpan and a Traxxas TQi R/C system and an APM2.5 coupled to a AR600 receiver and a DX7 transmitter. Both systems work fine.

    I calibrated the ESC while having the APM in the loop between the receiver and the ESC while in the manual mode. That was done after I had calibrated the radio in the CLI.

    You do have the throttle on APM output channel 3 and are using the elevator joystick as the throttle? The rover throttle range should be setup for 0 - 100%.

    You have the modes setup as auto, auto, learning, learning, manual, manual. You have verified that you are in the manual mode when the manual mode is selected on your transmitter?

    Are you sure that you do not have some aileron - elevator interaction on your transmitter that you do not know about?

    You have verified the radio channel ranges in the MP and you do not have some failsafe function being enabled?

    Hope that this might help get you started with your troubleshooting.



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