
Re: DIY motorized/timelapse head
Dmax wrote:
80 views and just one reply ? have I posted in the wrong section ?
Well, I wouldn't say it's the wrong section but there is a 'Timelapse Motion Control Systems & Dollies' section. Setup & Rigs is more of a showcase section.
Some thoughts:
I like your panning section. I'm not sure about the tilt axis. Is it stable?
Ramping is a good feature, but to achieve this I would say that the mechanism should have something like 0.01 degree precision. Maybe you can achieve that, since you're using encoders. I didn't know about the encoder in old Microsoft mice. Do you know what type of mouse I should look for if I want to savage that part?
What language are you using to program your 16F uC? Assembly? I moved to 18F parts (18F4620 and 18F2620 are favourites) to benefit from Microchip's free C compiler, floating point math libraries etc. For example, I use the hyperbolic tangent for ramps, rather than linear segments. The linear ramp - if that's what you're doing - is fine, but has a discontinuous first derivative, which can sometimes be seen in the end footage. Tanh has continuous derivatives.
For anything other than very simple interfaces I like using simple 4x4 keypads. Can't remember if it's the same on the 16F87x family, but I just stick it on PORTB and use the interrupt-on-change feature. Really simple.
Also, pay close attention to periodic error in your mechanism - personally I think this is more of a problem than backlash (more frequently discussed). I went to great trouble building a pan-tilt head, and for the most part it was a success, however it had a very subtle pulsing to its motion. Over time this became fairly irritating.