Somewhat basic questions about forces applied to levers

Question

Somewhat basic questions about forces applied to levers

flarobotdad (Mechanical)

(OP)

3 Jun 15 16:56

I am admittedly a tadpole in this world, so if you cannot bring yourself to respond positively then I understand.

I am developing an interest in remote photography, where cameras are either mounted high on stands or suspended from kite rigs and controlled remotely. Many different designs exist for the actual framework which holds the camera, and I am curious about the most efficient way to pivot or rotate a given load as it relates to the position of the actuator/servo and the pivot point. I would suppose there are some rudamentary instructional axioms which govern how to efficiently apply force to levers and pivot points to reduce the strain on the servo as well as generate the most amount of transferred force on the load.

This is just a random picture off google search as an example:
PICTURE OF KAP RIG

IF you look at that image, the tilt motion looks to be direct drive from the servo. I would think that there is a better way to apply that rotational power.

Additionally, if I have published this thread in the wrong section of the forum, I apologize in advance.

Nicholas

rjoto (Mechanical) · Answer 1 · 2015-06-03 18:59:59

From the picture I can see two points of rotation. The top one looks like it is geared down once from the servo. The one on the side looks like it is probably direct drive as you said. The picture's not very big so it's hard to tell. As long as you size your servo correctly it shouldn't be an issue. That's probably the most efficient way to do it but it probably depends on the size of your rig vs the size of the camera and how important weight is in the whole matter. Gearing it down once could also be an option. In general, I would probably stay away from "levers" for rotation. It complicates things and makes it harder to get linear rotation. Also make sure to mount your camera so the axes of rotation go through the center of mass. That's probably a much more important factor.

IRstuff (Aerospace) · Answer 2 · 2015-06-04 01:51:53

That's a two-axis pan and tilt. It looks like it's using fairly standard RC servos to drive the two axes. That actually is the optimum approach, assuming that the rotational inertia about that axis is rotationally symmetric, i.e., that it's balanced on that axis. These types of servos are generally relatively low speed, so any sort of gearing will tend to significantly drive down the angular speed.

Note that this type of gimbal will not do image stabilization, or will not do it well, so long lens imagery will tend to be blurry. Even still, if the UAV is small, it will have its own rotational disturbances, so some sort of electronic image stabilization should be looked into if video output is desired.

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MikeHalloran (Mechanical) · Answer 3 · 2015-06-04 02:17:36

Servo issues become someone else's problem when you use a quadcopter as a camera platform.

Mike Halloran
Pembroke Pines, FL, USA

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Somewhat basic questions about forces applied to levers