Control RC Servo with a joystick, hard wired?

I'm looking to make a camera control for a camera using some type of joystick. I've seen a few projects to make a servo driver but anyone have any ideas on how to make something with a joystick, just need two axis like a joystick. Anyone know how to tie a joystick into one of those drivers. I'd really like to have two joysticks controlling 4 servos. Thanks

Reply to
Barkster
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Sure. The servos need a nominal 1.5ms pulse that varies 1ms to 2ms over the lock to lock range of the servo. Couple of 555s should work, with a

3rd one triggering the variable pulse at a 50Hz rep rate.
Reply to
BobG

On 28 Mar 2006 14:15:08 -0800 in sci.electronics.design, "Barkster" wrote,

No. You have to use two of those drivers.

Reply to
David Harmon

A google search for "555 servo" will produce circuits like below that might can use the pots in the joystick. Might be easier to hack an RC unit like the bottom link to control the servos.

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Reply to
Si Ballenger

It's maybe not quite as simple as the other posters have suggested. Hooking the sticks directly to devices to generate a pulse train to move the servos will result in something that works, but the sticks will control position not velocity. Sticks central is point straight ahead, if you want it to point to a specific spot, you've got to hold the joysticks on that spot. (assuming a central return stick)

Reply to
Ian Stirling

I worked with some RC servos once, and at the time, there was a motor controller available, where the stick actually controlled the speed of the motor, and could reverse it. You would need some kind of end stops - those RC servos are designed to hold position if they lose the signal; with a motor controller, if you lose the signal, the motor keeps turning at the most recently commanded speed and can break stuff if you don't have some kind of limit switches.

Good Luck! Rich

Reply to
Rich Grise

Real easy if you are into microcontrollers. Read the sticks with A/D, do what you want with the data, then create your pulses in software.

Luhan Monat "Without Microcontrollers, we're pretty much screwed"

Reply to
Luhan

The servo will position itself at the speed the joystick is positioned, fast stick movement for fast servo movement, slow stick movement for slow stick movement.

You probably can use the buttons on the stick to switch the pulsed output on and off using something like a small double throw double pole relay. A setup could be two 555 chips, one for up/down, and one for left/right control. The pulsed outputs from these two chips go through the relay that is closed contacts when the stick button is pressed. Press the button and move the stick to position the two servos as desired, then release the button and the servos stay where they are and the stick can return to the neutral position. Send the relay outputs to a 6 position dual contact rotary switch so that up to 6 pan/tilt cams can be individually selected. I haven't used the 555 chips, but I've done much the same thing with a joystick connected to a computer to control my DIY servo pan/tilt cam (below).

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Reply to
Si Ballenger

Why use a uC where a simple NE556 will do? IMO they are still using some sort of pos or neg puls width modulation. ok, ok, size is almost the same, u can add ramp behavior, ... ;)

Heinz

Reply to
Heinz Liebhart

Did this with an AVRTiny. Actually the only way to do this conveniently.

You do *not* want to change the pulses according to the joystick position (like RC stuff does), you want to increase / decrease pulse lengths when the joystick is moved, and *leave it there* when the joystick is centered. The dreaded 555 will not do that! (unless you add a lot of extra hardware) (Any of the 6 ports of a garden variety HEF40106 will make a better pulse generator if you want to go that way :-)

If no pulse is offered to a servo (make sure it's a low impedance "0")

- the servo will remain at last position.

--
 - René
Reply to
René

Sweet camera control, guess it isn't as easy as I thought. I'm not looking for precision and this is how I stoped my servos from returning to center. I cut off the prong that moves the pot along with the control arm gear, thus giving me 360 degrees and stops where I quit sending pulses. Now if I can only hardwire it, even if I could hardwire a old controller straght to the servos, eliminating the reciever.

Reply to
Barkster

How about simply connecting a toggle switch directly to the motor in the servo? Or directly to the potentiometer (not using any electronics in the servo)? If your servo needs only very little power (and to move a camera, it probaly will), just try this. It may burn out the pot in your joystick, but it may be worth a try because it is probably the simpelest thing by far:

5V o---------------o---------------------- | | +-+ | | | R/2 | +-+ | | ,-. +-+ o-----[( M )]-------->| | R pot | `-´ +-+ +-+ | | | R/2 | +-+ | | < GNDo---------------o----------------------
Reply to
Matthias Melcher

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