I would like a PTZ controller that moves the camera in proportion to the movement of a control handle. In other words, the handle would control the camera in the same way that the handle on a standard tripod head moves a camera directly mounted on the head. Moving the handle x degrees up, down left, or right aims the camera x degrees down, up, right or left respectively. This is in contrast to the rate control offered by joysticks. Is there accepted terminology for such a control scheme?
You are indeed using the correct terminology.
Currently the only solution I am aware of is an example by an individual who builds tank simulators and it does not have any direct applications to cameras.
There is one other aspect to consider with such a controller... even if your joystick is able to issue the absolute movement commands the camera must be able to not only accept them but execute them properly.
As an example the PTZOptics P/T/Z camera utilize a belt drive system that if bumped causes the head to think it's in a different X,Y location... while the camera will accept absolute movement commands it has the potential to yield an incorrect result.
The most ideal scenario would be an "absolute movement controller" paired with a P/T/Z camera that utilizes servos so that it is always aware of it's current absolute location even when bumped.
The subject matter is definitely one I have been investigating but we do not currently have plans for anything to solve this issue.
As it is a subject of interest to me if you care to discuss it in more depth please let me know and it will be my pleasure.
Thanks for your reply. That is all very interesting. My application is streaming church services. 20 years ago our church had a television program which we shot with two 70's vintage Ikegami tube cameras (ITC-730?) mounted on tripods. So we had to provide space for the tripods, cameras, monitors, and cameramen, in the aisles of a small church. Now we have a much larger church, and much smaller SONY PTZ camera which we operate remotely with a joystick. After 10 years of practice I just can't do smooth camera moves with a joystick. With the old cameras we moved the camera exactly where we wanted it, as smoothly as we liked. Every time I try to use the joystick, I wish for my big old ugly camera.
It astounds me that that there's not a standard off-the-shelf absolute position PTZ. There have to be others who miss their old tripods like I do. I see football games with cameras running down wires to any position on the field. News broadcasts feature their robotic cameras. We have the technology. Now the cameras are arbitrarily small and can be mounted discreetly anywhere. But we only have rate control joysticks rather than linear position controls.
Your point about bumping the camera out of its known position is important when the camera is computer controlled, requiring predictable, repeatable moves. In fact the only cameras I find with absolute positioning are being used in computer controlled roles, for 3dof or 6dof simulations and the like. I think I am really looking for linear control as opposed to the rate controls of the joystick. My cameraman will position based on what he sees on the monitor, just as he did with the tripod. He won't mind if the camera/handle relationship has shifted by a degree or two since last week. In fact proportional linear control would work.
I agree that the system would be a closed loop servo arrangement, with optical encoders or some type sensor on both camera axes, which the controller will drive to match the control handle position. The best system will have minimum lag or overshoot in the control loop. The light weight of a small camera should accommodate those requirements nicely.
In my daydreams I picture building such a system myself. It would be a fun project. But I really thought there would be enough demand that I could find one somewhere, even an expensive one, on the shelf.
Again, thanks for the reply. It is certainly a subject of interest to me as well. I'm interested in any pointers you can offer.
I'm getting ready to pull the trigger and buy some new equipment, but I have the same concern as Kenneth. I would like to see a proportional control of the PTZ functions.
Might I assume that the joystick on the camera controller utilizes switches not potentiometers?
If it utilized potentiometers then the output of the potentiometer be used to modify the speed setting based on relative position.
I realize that this would require a major redesign of the controller, but well worth it! The way I see it there would be no modifications necessary to the cameras.