I am flying a Flamegear X468 gimbal on my DJI F550 Hexacopter. I am using HITEC HS65-MG analog servos.
The servo drives 10 degrees of tilt for every one degree of aircraft pitch. If the gimbal and aircraft are level with the ground, the gimbal will be pointing straight down to the ground with only 10 degrees of "Nose Up" of pitch from the aircraft. I currently am using the most current version of the APM mission planner 1.2.27. Is there some way to scale down the motor travel? I do not see anything in the mission planner configuration tool.
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Also, here's a little trick I used to help when tuning the gimbal settings:
Strap a laser pointer to the gimbal, so you can see the dot hitting the wall ahead. Then when you tilt the copter up and down you can see if the red dot stays in the same spot or has lag/gain on that axis. I found I needed different values for up versus down. Repeat for roll with the laser pointer aiming sideways.
It's much easier to see if the red dot is moving, rather than trying to eyeball whether the gimbal is staying level or not, particularly if you stick some tape to the wall where the red dot hits when level.
The PWM represents the position of the servo. Most servos are neutral at 1500 microseconds and have endpoints at or near 1000 microseconds (counterclockwise 60 degrees) and 2000 microseconds (clockwise 60 degrees). Some servos will have more than 60 degrees of rotation in each direction, like 90 degrees in each direction.
The degrees settings represent the capabilities of the gimbal (not the servo). So if the gimbal can pitch down 30 degrees and up 15 degrees those would be your minimum and maximum degrees for that axis. To reach those minimum and maximum degrees it might not take the full range of the servo (for example 1000-1750 microseconds instead of 1000-2000 microseconds).
By matching those parameters with the capabilities of the gimbal and the required servo positions for those angles it should perfectly counter the motion of the APM as long as the servo is fast enough to keep up (if the servo is not fast enough there might be some lag). The numbers don't have to be exact because not ever servo is the same but hopefully that gives you an idea of what each parameter means.
There are options in the Mission Planner to control the gimbal stabilization and control. It will be on the left side in the configuration mode, I think under advanced parameters or something like that. I'm not on a machine with the Mission Planner otherwise I would make some screenshots for you. Though if you can't find it I can post some more information this evening.
I'm having the exact opposite problem.
I've tried two servo's and either of them only move about 45 or 50 degrees, where I need them to travel more like 150 degrees. I could compensate a bit by rigging a super long servo arm, but it would be better if I could get the APM to drive them the full range. I have set everything to the 800-2200 servo range and -90 to 90 degrees. The servo(s) only travel a tiny fraction of that range.