I am just getting into Arduino because I am a DIY kind of person and I have a very specific project that I want to do.
I am an amateur photographer and videographer that specializes in landscapes. Long story short I would like to build a CableCam that would allow for me to run a chassis on a cable or set of cables that travels by way of a servo or stepper motor and also pans as it travels, for time lapse and standard video. Now, I will work through the programming later but to start I need advice on hardware.
For travel along a set of 2 cables, I have a design, but I need to know whether a stepper or servo would be recommended. They need to be able to hold roughly 8lbs in place along a relatively level plane and occasionally climb very shallow grades.
Which Arduino!? I want the controller module to be very small and removable so that I can program it and then plug it in and press run. I need good battery life given that i will be on the move (Separate power for the board and motors of course.) I know that I need two stepper motor shields or one dual shield but all of the literature is confusing and I truly cannot figure out what my smaller, most effective combination would be.
Also in the future I would like to add functionality to program it and perhaps abandon the time-lapse remotely via IR or bluetooth from my phone or a standard IR remote.
I apologize this was rushed but I am short on time while writing the post. I am so glad that this forum exists and I can't wait to get started.
Here's how I would approach this - if I am understanding your setup correctly:
kohlwebb:
I am an amateur photographer and videographer that specializes in landscapes. Long story short I would like to build a CableCam that would allow for me to run a chassis on a cable or set of cables that travels by way of a servo or stepper motor and also pans as it travels, for time lapse and standard video. Now, I will work through the programming later but to start I need advice on hardware.
First off, I would use two cables - doing so, while more complicated to setup, will likely be a more stable platform as the chassis moves.
kohlwebb:
For travel along a set of 2 cables, I have a design, but I need to know whether a stepper or servo would be recommended. They need to be able to hold roughly 8lbs in place along a relatively level plane and occasionally climb very shallow grades.
First off - I don't know what your design you have in mind is - so what I describe below may be completely different from what you had in mind. Or, it might be identical. Likely, it is somewhere in between.
If speed of movement isn't an issue, then servos may work ok. You'll likely want a fairly hefty servo - something along this line should work ok:
You would have to modify the servos to be continuous rotation (as these larger ones don't typically come this way). In fact that servo above might be overkill (actually, it probably is overkill). If you want to know what to use for actual torque, you'll have to calculate it based on a number of factors. I am going to let MarkT comment on this (hopefully he'll chime in) - otherwise, take a look on google on how to calculate torques based on shaft output size, mass of system being moved, max incline angles, etc. Get those numbers, maybe add 5-10 percent - and use that as you value (halve it for a single servo or stepper - if you plan to use two of them).
Take a look around ServoCity's site - they have a lot of great stuff that will likely help you.
Regardless of whether you use servos or steppers, I would use a pair, one on each side of the chassis - in the middle of the chassis. The camera should hang below this chassis. Inline with each shaft of the motors, but positioned slightly higher than the motors (but at the same level), should be a set of free-wheel pulleys with double flanges - screen door "wheels" that have a groove would work ok:
So - you would have a set of three axles - the outer two higher than the inner "axle" - with the middle axle being the two motors output axles from the gearbox - sorta like this:
That's a side view - but I think you'll understand. Basically, each cable goes over one pulley, then -wraps- around the axle of the stepper/servo, then goes over the other pulley. The shaft of the stepper/servo should be knurled to provide some "grip". Alternatively, you could use chain and sprockets - but that would be more complex and more expensive - depending on the run length.
I chose to design it with two servos instead of one, because you need to move along both cables - and a single servo/stepper driving one axle could introduce more complex mechanics (gearing, axles, bearings, etc). Note that if you use steppers, you will probably want to use ones with a gearbox (nothing too severe in ratio) - just to be able to stop the stepper and have it "hold" on an incline or such when no power is applied. For servos, this likely won't be an issue.
kohlwebb:
2. Which Arduino!? I want the controller module to be very small and removable so that I can program it and then plug it in and press run. I need good battery life given that i will be on the move (Separate power for the board and motors of course.) I know that I need two stepper motor shields or one dual shield but all of the literature is confusing and I truly cannot figure out what my smaller, most effective combination would be.
For your needs, I would go with something like a Arduino Nano - but even a standard Arduino would be fine; compared to the rest of the rig, it's still fairly small.
You'll need to size the batteries to your system - you might even want to go with off-board power, and run a power tether to the system. The motors will be fairly large energy hogs, and the lighter you can make the rig, the more time for power (especially if batteries are used) you'll have (because the weight of the batteries will be eliminated). Leave the Arduino on-board, and program it or set it up using USB (or bluetooth). If you code things right, you'll be able to do this fairly simply. There shouldn't be a need to remove the Arduino.
As for motor drivers - for servos, you don't need anything; just pair up the signal lines, attach power and ground (and hook the grounds of the servos to the ground of the Arduino!).
Steppers, though, get a little more tricky. You'll need proper stepper drivers sized for the stepper motors you select. You might want to check out Pololu's offerings:
Stay away from anything using an L298 or L293 - they won't be worth it.
kohlwebb:
Also in the future I would like to add functionality to program it and perhaps abandon the time-lapse remotely via IR or bluetooth from my phone or a standard IR remote.
You should be able to easily add this on, even using only a ATMega328 based Arduino (as long as you code things properly to conserve memory).
I hope all of the above helps you in some manner - or at least gives you some inspiration. Good luck with your project, however you end up building it!
