this is my first post on here, I've been busy building myself a quad based on a Flamewheel 450 style frame. Running a Arducopter with the latest firmware. once I had finished the main build i set about starting to test and calibrate everything.
now i have a Fr Sky D4R-II receiver hooked via cppm to the arducopter, now at this time my Transmiteer is a JR x2610 with Frsky DHT-U now i found during radio calibration that the channels were in the wrong order, now as i can't change on the Transmitter i swapped the channels on the APM all was well i thought, motors all spun up when armed, seamed to throttle up well, so i popped the props on to see how she would handle just taking the weight off, slight throttle up and she went to flip to the right, recalibrated the gyro double and triple check all connections and same again, weird i thought so i started to bug test. Full left roll and slight throttle and she was only trying to drift right.
So i decided to start eliminating items, put her into ESC calibration mode, calibrated motors and checked their spin and all seamed ok, re-fitted props (still in Cal mode) and carefully spin her up, she lifted the weight evenly and with gentle support on the top of the gps hovered for the first time :) so motors and ESC all good.
I then turned my attentions to the telemetry data, when i noticed something odd, the ouputs for motors 1 and 4, so i tried flashing the latest firmware, resetting all values to default, tried PID settings i found listed as basic start ones for my frame to try and eleminate gain issues and still no change.
then over the weekend it hit me, when i changed the RCMAP settings I switched the roll and throttle. so this evening i sat and had a play, and re calibrated the radio but leaving the throttle in center rather than rest.... and she hovered!
It appears that using RCMAP to switch the channels doesn't switch the attributes for that channel which can very easily lead to a quad flipping over.
I'm not sure if others have come across this or know of anyway to solve as i'm concerned that my failsafes won't work correctly as it stands. I searched for hours over the weekend but kept turning up the same responses of recalibrating radios and ESC's when it turns out to be a firmware glitch, I hope my findings can be of use to others, I'm aware i could avoid by using a bigger receiver but i used the one i have to save wiring, space and weight. I am awaiting a 9XR-Pro atm so at least i can revert the apm back to defaults and it not be a concern.
This is a known issue with APM and RCMAP. There should be several post regarding this bug. The RC1-4 do not follow the RCMAP causing the issue. This can be corrected by doing a radio calibration and then swap the values to the correct position to match the map.
Pixhawk with the latest firmware corrects this issue.
so i'm I correct in understanding that where i have swapped channels 1 and 3, then i should alter the various values of RC1-4 to represent the correct values, ie rc1 is currently the figures for ch3 and rc3 the values related to ch1. ATM i'm on APM 2.8, but I would like to build a hex once i've cut my teeth on this one and am thinking when i do i'll go down the route of pixhawk.
Thank you for your help, I shall sit down and have a play with those settings