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    Odd behavior from ModalAI 4 in 1 ESC

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    • M
      Matthew Wellner @Alex Kushleyev
      last edited by 21 May 2024, 06:27

      @Alex-Kushleyev the motor / prop combination is a mn4004 or mn4006 with a tmotor MS1101.

      I switched over to the 138 ESC last night to see if the ESC board was just bad, but I'm still having similar issues.

      Thanks again for the help!
      Matt

      A 1 Reply Last reply 21 May 2024, 14:36 Reply Quote 0
      • A
        Alex Kushleyev ModalAI Team @Matthew Wellner
        last edited by Alex Kushleyev 21 May 2024, 14:37 21 May 2024, 14:36

        @Matthew-Wellner , remember we had a discussion about 5 months ago, where i helped with the tuning. At that time, did you get the setup to work? https://forum.modalai.com/topic/2979/can-you-power-voxl2-from-the-modalai-6s-esc/ . Did anything change since then in terms of your motor / propeller setup? did this issue suddenly start occurring without a hardware change? (any crashes that could have damaged the ESC?)

        Also, is your motor a Tmotor MN4006 or SunnySky? Also, what KV and what voltage are you applying (4s / 6s). I do have these propellers.

        Alex

        M 1 Reply Last reply 21 May 2024, 17:25 Reply Quote 0
        • M
          Matthew Wellner @Alex Kushleyev
          last edited by 21 May 2024, 17:25

          @Alex-Kushleyev sorry for the slow response. I never actually test flew the setup outside of a few quick lift offs because we were making some housing changes. I thought the platform just needed to be tuned.

          I have run 3 different motors with similar behaviors - sunnysky 4004 (400kv), tmotor 4004 (400kv) and tmotor 4006 (380kv) all at 6s voltage with 11" props. I also tried 10" master airscrew props with the 4006s.

          I swapped the 0134-6 ESC with a 0138 ESC yesterday after the the 0134-6 got hot enough that, I think, one of the motor wires desoldered itself.

          Thanks again for the help!
          Matt

          A 1 Reply Last reply 21 May 2024, 19:08 Reply Quote 0
          • A
            Alex Kushleyev ModalAI Team @Matthew Wellner
            last edited by 21 May 2024, 19:08

            @Matthew-Wellner , thanks for the clarification. I do have the tmotor 4006 and sunysky motors, since i ordered it last time we had the discussion.

            Lets take a look at the px4 log once you have a chance to share it. Thanks.

            Alex

            M 1 Reply Last reply 21 May 2024, 19:36 Reply Quote 0
            • M
              Matthew Wellner @Alex Kushleyev
              last edited by 21 May 2024, 19:36

              @Alex-Kushleyev I'm sorry to have to ask this, but is there a way to upload the logs via this interface? When I try and upload a file I get a permissions error.

              A 1 Reply Last reply 21 May 2024, 19:38 Reply Quote 0
              • A
                Alex Kushleyev ModalAI Team @Matthew Wellner
                last edited by 21 May 2024, 19:38

                @Matthew-Wellner , no problem, if you are ok sharing the log publicly, here is how we usually do it : upload it here https://review.px4.io/ and send a link. from there i can inspect and download the log for further analysis.

                M 1 Reply Last reply 21 May 2024, 19:39 Reply Quote 0
                • M
                  Matthew Wellner @Alex Kushleyev
                  last edited by 21 May 2024, 19:39

                  @Alex-Kushleyev Is there a way to share it privately? Otherwise I can send it to the link you already shared.

                  A 1 Reply Last reply 21 May 2024, 20:14 Reply Quote 0
                  • A
                    Alex Kushleyev ModalAI Team @Matthew Wellner
                    last edited by 21 May 2024, 20:14

                    @Matthew-Wellner , i will reach out to you via email

                    M 1 Reply Last reply 21 May 2024, 20:35 Reply Quote 0
                    • M
                      Matthew Wellner @Alex Kushleyev
                      last edited by 21 May 2024, 20:35

                      @Alex-Kushleyev thanks! I responded. The ESC parameters file were exactly as you example except for the calibration parameters (the 3 numbers we need from the calibration routine). I averaged the numbers I collected from running the calibration on each ESC.

                      A 1 Reply Last reply 21 May 2024, 21:00 Reply Quote 0
                      • A
                        Alex Kushleyev ModalAI Team @Matthew Wellner
                        last edited by Alex Kushleyev 21 May 2024, 21:00 21 May 2024, 21:00

                        @Matthew-Wellner , As we discussed offline, I am going to post the summary for the likely issue here:

                        By setting "demag_timing: 1" in esc params, it enabled some experimental feature, which fails to work correctly above certain rpm. It prevents motor from spinning faster when more power is applied (above a certain rpm). You can see from plots above, the desired command for motor 4 (purple) goes higher, but actual rpm is flat lined around 5700rpm (black). Also the current jumps up significantly for motor 4 (black) when it hits that ceiling.

                        For your motor, please disable this "feature" by setting demag_timing to 0. Depending on your current timing advance, we may keep that the same or increase slightly.

                        After disabling demag_timing-> 0, i would recommend performing rpm step tests to make sure the de-syncs still do not happen.

                        I am sorry about this, I will update documentation to not recommend using this feature.

                        9ac17b56-3431-408e-bd34-a7006eeb55ef-image.png

                        zoomed in
                        c12f7747-3523-416b-8467-f462ee7b7561-image.png

                        Alex

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