Brushless Gimbals Revisited - 2018

edited October 12 in Control Systems
NB. This new discussion has been augmented with some of my notes from the thread titled 'Xiaomi Yi or SJCam'.

The newer action cameras and lighter 3 axis brushless gimbals are well advanced since I first started out with gimbals 3 years ago. See:
arch.ced.berkeley.edu/kap/discuss/index.php?p=/discussion/5704/building-a-gimbal-kap-rig
and
arch.ced.berkeley.edu/kap/discuss/index.php?p=/discussion/5875/kaping-with-brushless-gimbal-rigs-12-months-on

The most obvious improvement is in the software used to set up the gimbal’s control parameters. In the ‘old days’ you could spend hours adjusting the PIDs and still not get them right. The initialisation phase before each shoot required absolute stillness and could take up to a minute to complete and worst of all the gimbal could lose lock hundreds of feet in the air requiring a return trip to terra firma for a re-start……no fun at all!

The new Tarot T-3D gimbal I have tested is a great leap forward by comparison. I’ve been flying it for a few weeks now and even in gusty 30 knot winds it has never lost lock. It initialises in a few seconds and best of all the main PID parameters are easily adjustable even when using cameras other than the GoPro intended by the manufacturer. But its main feature is the ability to vary the speed of rotation in all three axes to match the camera’s lens, ie slow for wide angle lenses and even slower for narrow or telephoto lenses. This enables perfect tracking and panning in the hands of a skilled operator.

Yi 4K Gimbal KAP Rig
Yi 4K Gimbal KAP Rig

This rig uses the the Tarot gimbal plus an additional pan servo drive. The brushless gimbal has a panning range of +/- 125 degrees either side of centre with an allowance of 20 degrees more to cater for wind disturbances. This range is adequate for most circumstances but the ‘blind’ area behind the camera may well be of interest but inaccessible particularly after a change in wind direction. The pan servo allows easy centring of the camera prior to a KAV shoot ensuring the whole scene can be captured as the target object is tracked along it's path using the gimbal pan control.

A word of caution for those intending to use the Tarot gimbal for kite aerial video:

The Tarot and other readily available brushless gimbals are intended for the drone market and therefore the gimbal has been designed to follow the drone’s heading. Small unintended variations in heading are corrected by the gimbal while larger variations are assumed to be intentional and the gimbal will slowly follow, ensuring that the camera’s heading always aligns with the drone’s. The gimbal's pitch and roll motors keep the camera fixed at the right angle regardless of the drone or kite movement.

So, a sweeping pan made by the drone is tracked by the camera which will also sweep around following the drone’s heading albeit more slowly and gently in line with gimbal’s internal settings.

The downside of this is that when fixed to a kite string, significant changes in wind direction will mimic the drone’s sweeping pan movement and the camera will slowly track around to the new heading. In many cases this is of little concern since most videos require editing anyway and any unintended panning movement can be easily cut from the final version.

But if you’re expecting a rock solid platform for your camera then a drone gimbal may not be your best bet. Perhaps others could report on their experiences and point the way to the perfect solution!

Al

Comments

  • Very good idea the opening of this new subject, I have understood your warning, I remain motivated and I will therefore think a little more about this project and the difficulties to balance the basket, at the same time, I will carefully follow the exchanges, images and videos made with this technique ...
    Thank you Al
    Hervé
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