I purchased an inexpensive gimbal for my quadcopter from Hobbyking, the actioncam inline gimbal for FPV and multi-rotor product id 450000070-0. It’s only $9 and doesn’t have to mount on the bottom of the quadcopter which solves my main issue since the QC has short legs and a battery on the bottom.
It came with no instructions just an exploded view and the above picture on their web site.
Assembly was reasonably easy though did things a little differently so the gimbal would mount on my talon v2 frame.
I am going to mount the gimbal to the top of my quadcopter and let it hang over the front. So to start, I remove the nylon screws and put two 20mm nylon standoff in instead:
Fortunately, I have a decent stock of nylon parts these days since purchasing this from amazon:
I then assembled the damping balls into the base plate and attached the base plate to the standoffs like this:
This mount is not rigid, but it is not unreasonable. If I’m not satisfied with it I will try to figure out something different.
When purchasing this unit, the servos recommended by someone in the reviews were wrong. I’m not savvy on the various sizes of servos, but you need one like this HobbyKing HK15178B for the pitch servo – it will fit in the cut out perfect and has the appropriate mounting holes:
Mount it like this:
The roll servo is a normal sized servo. I used a Hitec HS-322HD though the HK15138 is the same size. Note: I tried using a smaller servo here (HK15178B) to save weight, but it didn’t work very well – it flexed quite a bit more than a normal servo plus you can’t use the included mounting bolts. Here is the servo mounted between the damping plate and gear mounting plate:
Attaching the two subassemblies together you end up with this:
This is attached to the mounting plate already on the quadcopter by connecting it to the damping balls. Here is the entire assembly mounted on the quadcopter:
Note the nylon nuts run thru the outside damping balls: DO NOT do that. I ended up removing them and getting much more stable video.
and a front view:
Connecting the servos to the KK 2.1 board with rev 1.6 of firmware was a piece of cake – just connect the roll servo to M7 (motor 7) on the KK board and the pitch servo (the smaller white one) to M8.
All instructions I have seen indicates the servos will not work unless the props are spinning. That was not the case for me. My guess is firmware prior to 1.6 had this limitation. So I did not need to remove the props to set everything up; however, I did anyway the first time I went through this procedure just to be safe (the props are on in the picture the second time I went through this to document it).
I’ve seen various youtube videos on configuring the camera gimbal settings including this one:
Some additional tips I found useful. First, this gimbal is in a location making it hard to use a torpedo level. I used a level that goes into the hot shoe of my DSLR. It was perfect for this (you can get them at B&H photo):
With the level sitting in the gopro cradle, I started with the roll and pitch offset at 50 (and the gains at 500) and physically moved the parts on the servo hubs until they were as close to level as I could get them. Then I adjusted them with the roll and pitch offsets until the cradle was level on both axis. For me, the settings were:
Roll Offset: 52 Pitch Offset: 52
I then tilted the QC on the roll and pitch axis to see how I needed to adjust the gain settings. To my surprise, the servos went in the wrong direction. If I rolled the QC left, the servo moved the cradle even further left.
That was a moment of panic because I have not seen how to handle that situation anywhere. I figured since everything was working in reverse perhaps an initial value of -500 for both gain settings would be a good start. Sure enough, that worked and the servos countered the movements.
From that point on, it was just a matter of playing with the gains until I could rotate the QC on either axis and the gopro cradle would stay pretty level.
My settings for the gains are:
Roll Gain: -590 Pitch Gain: -590
At that point I was done and ready to strap in a gopro:
Here is a video of the gimbal in action and side by side video of the QC with and without the gimbal. It most definitely keeps the horizon fairly level. There is still some shaking going on and I plan to address that next.