Joystick controller

[blimpguy]

Would like to build a 2 axis camera controller for HD cameras that is joystick controlled. There is a unit out there that does this from a small joystick controller runing pan, tilt and travel for time lapse.
It's programable to tell the cameras to go to preset positions.

Where do I start? All the controllers I have looked at are rather large. The site is Kessler Crane™ - Quality Professional Camera Cranes, Camera Jib & Camera Support Products - Home for the joystick controller.


Tks

[ksanalytical]

Blimp,

I'm by no means an expert, but the basics will be the input device (the joystick), a processor of some kind, and a drive/motor combination. At least that would cover the electronics.

Your choice of joystick would be decided based on whether you need variable speed or fixed speed driving. Assuming you want the thing to move faster as you push the joystick farther in a particular direction, you'll want a potentiometric joystick. The position of the stick will be output to the controller by two DC voltages, one for X and one for Y, which will increase of decrease based in its position.

If you're comfortable with linking the whole setup to a PC, you can use Mach3 or EMC2 as the controller to gain a lot of powerful motion control options very easily. You can even use an XBox controller as the joystick. If not, and no professional solution is within your budget, you're into programming a microcontroller. That's a whole new can of worms, but completely possible. Mach will allow you to drive to specific positions, reference the drives to a "home" position and even "learn" a series of movements to be later repeated. You could even use G-code to write your own custom motions.

The driver/motor part should probably be based on servos for the smoothest accelleration. Gecko makes excellent and reasonably priced drives which are compatible with small servo motors. I've had good luck with combinations from Home Shop CNC. These may be a little beefier than you need unless you're talking about a boom arm of some sort. They'll interface smoothly with Mach3 through the parallel port of the PC or by USb if you add a SmoothStepper between the computer and the drives. A breakout board is a good idea even for simple setups like this. :: CNC4PC :: iNtRo has excellent options. Particularly the C11T board which is designed to work specifically with Gecko servo drives.

Good luck.

Ken

[blimpguy]

Ken,

Thanks a bunch for taking the time to write. Now I have a startiing point that looks
promising.
I've read your post several times over and have looked at the links. I believe I understand the majority of what I need to research except the boards. I'm not
sure how the C11T and gecko drive work? Are both required to make the system work?
You were correct when your assumed a proportional joystick. I want to be able to pull
the joystick and ramp up speed as required. I worked with a crane crew last summer
and the owner slowly panned and tilted the camera at the end of an 85 foot crane. The
joystick plugged into a small box that sat on the table with pots to control the the speed
of the motors from the joystick.
I'm assuming this is where the C11T or the Gecko drive is going to be positioned. The joystick plugs into the C11T which takes input and converts the signal to the motors on
the control head ? Where does the gecko come in ?
I's like to use Mach 3 to remember the positions and for time lapse use. It like to be able to use both the joystick and the Mach 3 together or use the joystick alone. The memory
use is down the road. For know I'd like to be able to build a head the I can pan and tilt.
The end result is to be able to have a head on a trolley with a pre programmed shot. The easiest way to see a demo is at camBLOCK&#0153 | Modular Motion Control.

Thanks again for your help,

Jeff

[ksanalytical]

Jeff,

Sorry for being so slow. I travel most of the time and don't monitor this forum all that closely.

The C11T stands between the computer and the machine itself. A good one adds protection for the PC through optoisolation of the pins. Sounds fancy, but it's a simple idea.

The Gecko drivers are little electronic components which receive 5V pulses from the breakout board (C11T), PIC chip or direct from the parallel port. The drivers convert this into high amperage output to a motor. There are different drivers for stepper motors and servo motors. Your application would seem to lend itself to servos. Gecko G320X drivers are very popular, but they include some features designed for safety and motor protection which make them a little more complicated to operate. For instance, they require a 5 second 5V signal on the fault pin of the driver each time you start them up. The C11T board includes a simple microcontroller which takes care of fault monitoring and resetting. If you use steppers, the C11G board is comparable.

The joystick control will be much easier to implement through Mach3. If you stuck with gecko drives, you would want to program a microcontroller (PIC, AVR/Arduino or even a STAMP kit chip from RadioShack) which would convert the analog signal from the joystick to digital pulses for the drivers. This would be a substantial increase in complexity and would be best attempted after succeeding with the Mach3 interface first. The C11T will not attach directly to a joystick and perform any kind of processing on that input. for the purposes of the motors, it just passes digital pulses from the computer to the drivers.

Camblock looks really cool and would be very well suited to these types of controls. Good luck.

Ken