I've been doing quite a lot of research on cable camera systems and I've decided to build one with a budget of around $10,000, but it may take more.

This is going to be a pretty big project and any advice when I'm going through this would be appreciated.

Right now I am trying to figure out the type and size of motor I will need for the movement of the trolley up and down the cable. I've decided to use one main 3/8 cable for the support instead of two because of easier and quicker set-up times. I'm also planning on having another, maybe nylon, cable connected to the trolley on each side to pull it up and down. I will draw a diagram perhaps. As for the motor I need to find out what the torque and rpm will be

I'll be using a 12" diameter wheel for the pulley system.

It needs to be able to go up about a 50% grade so like 45 degree angle

A max speed of about 35mph when cable is fairly flat

Carry about 50lbs max on the trolley.

I'm going to buy a wireless controlled motorized remote head to attach

I'm not sure how many of you out there are involved with using this type of setup, but I could use the help of anyone who is skilled in the RC department even or anyone who wants to help out.

Jeremy

I've been doing quite a lot of research on cable camera systems and I've decided to build one with a budget of around $10,000, but it may take more.

This is going to be a pretty big project and any advice when I'm going through this would be appreciated.

Right now I am trying to figure out the type and size of motor I will need for the movement of the trolley up and down the cable. I've decided to use one main 3/8 cable for the support instead of two because of easier and quicker set-up times. I'm also planning on having another, maybe nylon, cable connected to the trolley on each side to pull it up and down. I will draw a diagram perhaps. As for the motor I need to find out what the torque and rpm will be

I'll be using a 12" diameter wheel for the pulley system.

It needs to be able to go up about a 50% grade so like 45 degree angle

A max speed of about 35mph when cable is fairly flat

Carry about 50lbs max on the trolley.

I'm going to buy a wireless controlled motorized remote head to attach

I'm not sure how many of you out there are involved with using this type of setup, but I could use the help of anyone who is skilled in the RC department even or anyone who wants to help out.

Jeremy

Well, that does sound rather ambitious! What will it be used for? How are you going to stretch, or maintain tension on the cable?

Mike

Mostly action, sports, outdoor shots over canyons, events. Things like that.

The cable will be secured to tress or strong structures and will be anchored using steel cable anchors and winches.

you can use a cable winch found on 4x4 cars (the ones bolted on the front bumber of cars), it is very powerfull, runs on 12v, some have a remote control.
you just need to add a controller for speed and replace the cable with a thinner/longer one, and they are cheap.

If anyone has any knowledge of what type of electric motor would suit this job that would be a big help

any 12V DC motor with good multiplier would fit. you can find some for under 20$ at http://www.jameco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&langId=-1&categoryId=351540.
choose high torque , mid speed (30-50 RPM).
you add a small PWM controller to control speed and direction.
My opinion is you should move the cable not the camera on the cable.
a simple pulley at one end , the motor at the other end.
in case of problem, you can get you camera back, it does not stay stuck in the middle.

Sorry, I meant motor for the pulley system for the trolley going up and down the cable.

Finding a high precision motor is most likely in the $1000 range. I am thinking of having one main steel cable for the trolley to ride on and all of the movement will be controlled from another pulley system. A motor on one end, and a cable wraped around connecting to the trolley and wrapped back around to the other side. A motor able to bring this up to speeds of 30-35mph and carry about a 40-50lb trolley is what I'm trying to find.

I'm also trying to find a controller system similar to what controls a motorized head that I could set up to the motor pulling the camera. I don't want to use a RC hobby type controller.

With the weight you wish to suspend and the speed you want to move it, you will spend a good chunk of money. Fifty pounds suspended at any distance is going to put a load on the cable.

Like you mentioned, one cable to suspend then another lighter cable to move the camera would be best.

I'll check, but McMaster Carr and Grainger are great places to look. You will probably need a gear reduced motor will variable speed and it will probably in the 1 hp range, plus reversable.

Don't think you really want to do this like have have said, as it will cost a small fortune. Well into the thousands for something reliable.

A much lighter camera dolly/trolly and a less ambitious speed would seem in order.

Mike

Mike

With the weight you wish to suspend and the speed you want to move it, you will spend a good chunk of money. Fifty pounds suspended at any distance is going to put a load on the cable.

Like you mentioned, one cable to suspend then another lighter cable to move the camera would be best.

I'll check, but McMaster Carr and Grainger are great places to look. You will probably need a gear reduced motor will variable speed and it will probably in the 1 hp range, plus reversable.

Don't think you really want to do this like have have said, as it will cost a small fortune. Well into the thousands for something reliable.

A much lighter camera dolly/trolly and a less ambitious speed would seem in order.

Mike

Mike

The weight on the suspended cable is not an issue, we easily can do a 1000' 200lbs man ridden zipline type setup.

Like I said our budget for this project is around $10,000, we're aware that we are in need of an expensive motor. The 50lb weight is going to be the absolute max as with the 50% grade. The weight may be closer to 20-25lbs depending on cameras used and gyro.

The speed of the trolley is an must as the objects being filmed will be traveling at about that speed.

Thanks for those sites!

speed is not really a problem, acceleration is.
if you build your system with minimum friction, small motors will fit your needs for cheap, but you will not be able to start and stop at high speed or climb gig slope (45 degrees is a lot !)
you can cheat by using magnetic breaks for deceleration.
for the design of my crane, i choose the oopic controller (small processor on a board) with the magnevation controller (piggy board PWM board for 2 motors). Add a joystick and few line of code and you can drive almost any small device you want for less than 200$.
in your case you could go for a heavier PWM driver and bigger motor (like found in old big printers). You can easily build a demultiplier with 2 gear and a gear belt.
if can go lightweigth, you can even build a standalone motorized sled that run with a small cam on a cable. i am sur you can get hi-speed easily then.

Yeah, I'm going to have to find something with a high holding torque to be able to stop it on that angle with weight and powerful enough to get it moving once stopped. I do not expect it to go up a 45 degree slope with 50lbs at 35mph. Just at a decent speed. I need the fast speed at the most level point of the cable.

OK, If you really want help, why not list the real specifications you are looking to achieve.

Lengths, weights, etc..... Then we can help!

Mike

Those basically are the specs.

I will need to to be 1000-1200' in length.

Reach speeds up to 35mph.

Be able to climb up a 50% grade, maybe not at the full speed.

Carry a max of 50lbs.

50 lbs is huge. if you can accept to go with a 110v AC motor, you can take any motor (from a drilling machine for example or washing machine).
if you need to go on battery, it will be pretty difficult to find one.
http://www.surplusshed.com/pages/item/m2556.html
http://www.surplusshed.com/pages/item/m2237.html
but for the specs you mentioned, you will need a really bigger motor than that.
(do forget you have to move 2000' of cable either)

How about this

http://www.baldor.com/products/detail.asp?1=1&page=3&catalogonly=1&catalog=CDP3445&product=DC+Motors&family=General+Purpose%7Cvw%5FDCMotors%5FGeneralPurpose

I hate to be the bubble-buster, but this idea has red flags all over it.

How often will this system be used? If its a one-time thing, it'll be a LOT cheaper to rent. Also, if its an all-the-time thing or you're hiring it out, you should be careful of patent infringement. Checking patents on existing systems can help you figure out methods of implimentation, while also informing you of how you could possibly get in trouble. Believe it or not, you can infringe on a patent without ever selling/renting your construction. I believe Garrett Brown still has the patent on this technology. Just giving a heads up.

On the safety front, make sure that ALL liability is thought of. Cable can do nasty things under tension, things can fall, etc... And make sure to mount a stress indicator inline with the cable so you can monitor the forces going through it - safety first.

That said, sounds like a fun project. Good luck!

Renting is not an option, as we will be in many different locations and many different set-ups. A that price we could have ended up buying the $250,000 SuperflyCam. I believe their patents expired in 2004 actually.

I am aware the dangers of cable under tension.

Thanks

the motor you mentionned look very nice.
It runs under 90V (not specified if AC or DV, nor if it can runs in both direction).
The power should be ok.
The only problem i see with our specs is the length of cable.
1000' is very long in one shot and you will need a huge tension to keep it straigth. Huge tension = big cable =really heavy weight.
you will have to make very precise calculation to know if the cable will be able to support its own weight + the weight of sled + effort on start and stop.
i am living in switzerland, so such installation (basically a small skilift) is not uncommon.
You should try to contact somes companies selling skilift for small place, you could get an almost ready made system for cheaper than in video systems.

look here, there is almost all what you need
http://skilift.nashacanada.com/

The weight won't be bad. I'll be using a polyethylene synthetic rope with a breaking strength of close to 20,000 lbs for a 3/8" rope weighing only 3.5lbs per 100'. The rope only has a 4-5% stretch at the breaking point. So less than 1% at working load.

I wouldn't use a 3/8 at 1000', I'm just showing that it doesn't weigh much. The tension at about 400' is only near 1000lbs with weight on cable.

here is a link to an expample of how it may be made www.aptosproductions.com/example.htm

i think you will need to use a design of sled where there is no part hanging over or under the cable.(a flat box with cable running on the side) this will prevent balancing due to wind, acceleration and decceleration.
http://www.giroud2.com/divers/image1.gif
the cable in the middle is for support, while the 2 other cables is the cable loop for displacement.(that is not a good design because difference in tension will induce rolling, so i would prefer to have the support cable outside and the motor cable inside, with the motor in the sled, but this is ok for light design only because small motor and small battery)
you can even make the camera being static inside the box and make a small turret with a surface mirror that can be oriented.
so the mechanism becomes very small an light.
I think a 10 to 15 HP motor will be enough.

The upper balance would be for a ken-lab gyro. I do like the idea of having a cable on each side. I've seen that design before and its works pretty good. Only thing is set-up times get much longer.

Ideally you'll probably need two gyros. I'm told these things suck a fair amount of power and then you might have another issue. They obviously will resist all afforts at moving the rig so acceleration will be limited. Good controllers can be programmed to factor that in.
Quite apart from the mechanics the control logic could be quite a thing to engineer depending on if you want absolute positioning of the camera or not.
I'd also figure in some effort at the aerodynamics of the rig, at 35mph you'll have quite a wind load to contend with.
Some critical frequency analysis of the whole system might be warranted, a long cable with a moving load in the middle could get into a very nasty oscillation either excited by it's own motion or wind. Dynamic tension control might help or else magnetic dampers on the cable tensioners.

Wow, really you think it will take a 10-15hp motor? To the wheel that turns the cable I will only need about 850rpm with a 12" wheel. And I calculated the 50lbs of weight being pulled at a 45 degree angle and it came out it be about 35.4 lbs.

I was thinking about a 5hp motor geared properly would be fine, but I may be wrong

Bob, Those are some good points

The controls for the camera will be from a wireless remote head stystem that we're going to buy so that will make things a lot easier than making our own.

I think with the points you made Girouds recommendation of having two cables would be a much better idea

I'd be looking at a cable to the camera for camera controls and power etc.
The batteries to run the camera, gyros and head are going to get heavy, really depends on how long you need to run the thing for. That does however add the complication of needing a cable winder with sliprings, messy for video but so is RF over that distance and very expensive if you're after a good live feed from the camera. Plus worse still all the RF systems have a big delay in them, the vision is encoded to mpeg-2 and then decoded in the receiver, something like an 8 frame delay.
Big problem during the Olympics down here, I think everything had to be delayed to match the roving cams on RF links.
Now that's fine when the camera operator sees the vision in RT but if you're trying to control a camera remotely with such a big delay, you'll have a problem.

Hmmm...
Dynamic tension control ,magnetic dampers, gyro, remote control, moving head, wireless transmission...
it iseems it will cost more than 10.000.
For the motor, you are right, 5 HP would be just enough, but it will suffer during acceleration.
for positionning on the cable, you put a simple wheel + a some reset mark on the cable (to prevent slippage) , it should cost almost nothing
you will find everything at http://www.totalrobots.com/access_files/sensors.htm#wheelwatcher

synthetic rope/wire, were would the best place to buy this be? I am in Australia so would it be better to buy local or from overseas which I am happy to if it is cheaper.

[QUOTE=Jeremy Teman;645249]Mostly action, sports, outdoor shots over canyons, events. Things like that.

QUOTE]

For that type of jobs I'd use a large RC Helecopter, except for covering stadiums that is. There is one available for around that price and they even include a HDV camera :-)

Andrew, you want to try to find some rope for about the $1-1.50/per foot range. I'm not sure where would be the best place for you, but I'm sure if you start searching around and getting quotes you'll know soon enough. Many boating companies have nice cordage that would work just fine. Just make sure you are getting something strong enough, like 30,000+lbs of breaking strength for a 5/16 rope. Same goes for the wire if you decide to go that route.

Andy, I don't believe I would be able to get the smoothness I'm looking for with a RC heli. Plus it will need to be able to mount a 35mm film camera as well. I would like to eventually buy/use one for getting angles not possible with a cable setup if you can get them at that price.

Where do you find a RC helicopter like you mentioned?