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 The opposite of timelapse - very fast motion rig... 
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Post The opposite of timelapse - very fast motion rig...
This is kind of off topic but still cool I think... :o



Fri Nov 16, 2012 2:04 am
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Post Re: The opposite of timelapse - very fast motion rig...
Very cool! Its a good time to remind everyone about Mantis because Dragonframe is finally getting up to normal speeds. I don't know why Mantis has been overlooked on this forum for so long. People here have been waiting and waiting for a fast version of Dragon while Mantis has been offering a nearly identical capability for a long time. You're the biggest secret on Timescapes. Chat it up a bit more. I think Dragonframe got a big boost here because a couple of Timescapes members have been showing off what their Dragon rigs can do, and the rest of us are copying them when we can afford it. Maybe you could post some interesting shots done with Mantis or some "how to do it videos", they seem to get people talking.


Fri Nov 16, 2012 6:40 am
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Post Re: The opposite of timelapse - very fast motion rig...
Here you go, a VERY highspeed dolly. Just put the camera in the pouch, start the video, and let-er-rip

Image

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Fri Nov 16, 2012 7:30 am
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Post Re: The opposite of timelapse - very fast motion rig...
sciencelookers wrote:
Very cool! Its a good time to remind everyone about Mantis because Dragonframe is finally getting up to normal speeds. I don't know why Mantis has been overlooked on this forum for so long. People here have been waiting and waiting for a fast version of Dragon while Mantis has been offering a nearly identical capability for a long time. You're the biggest secret on Timescapes. Chat it up a bit more. I think Dragonframe got a big boost here because a couple of Timescapes members have been showing off what their Dragon rigs can do, and the rest of us are copying them when we can afford it. Maybe you could post some interesting shots done with Mantis or some "how to do it videos", they seem to get people talking.


My take right or wrong on Mantis vis Dragonframe is that the first appears to be specialist software where as the latter is more mainstream / accessible Ie. hit the Buy button and its ready to use. Convince us otherwise ;)

Like the fast motion in the first post and as for the other "trajectory shot"..............LOL

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Fri Nov 16, 2012 11:12 am
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Post Re: The opposite of timelapse - very fast motion rig...
Only problem with the slingshot is it's not really "repeatable" which is the basic requirement for moco... :)


"My take right or wrong on Mantis vis Dragonframe is that the first appears to be specialist software where as the latter is more mainstream / accessible Ie. hit the Buy button and its ready to use. Convince us otherwise..."

If you want to buy Mantis it's pretty easy to get. It's also a dedicated motion control system - no compromises and lots more features than DragonFrame. Granted no "Buy It Now" Button - but I prefer to discuss first with the customer and be able to confirm it's really what they expect and need. I also provide a lot of direct support helping clients develop their rigs and respond to feedback on improvements and additions to the software. That is not what you would expect or get easily from a mainstream product...

But - yes - maybe some more show and tell videos might be a good idea...


Fri Nov 16, 2012 5:39 pm
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Post Re: The opposite of timelapse - very fast motion rig...
geraldft wrote:
Only problem with the slingshot is it's not really "repeatable" which is the basic requirement for moco... :)


"My take right or wrong on Mantis vis Dragonframe is that the first appears to be specialist software where as the latter is more mainstream / accessible Ie. hit the Buy button and its ready to use. Convince us otherwise..."

If you want to buy Mantis it's pretty easy to get. It's also a dedicated motion control system - no compromises and lots more features than DragonFrame. Granted no "Buy It Now" Button - but I prefer to discuss first with the customer and be able to confirm it's really what they expect and need. I also provide a lot of direct support helping clients develop their rigs and respond to feedback on improvements and additions to the software. That is not what you would expect or get easily from a mainstream product...

But - yes - maybe some more show and tell videos might be a good idea...


If I knew what I wanted then maybe Mantis would be a better choice and there lies the problem. I started with 1 axis and have now almost wired my controller for my current 6 motor configuration. Next...............??? So I would never be able to tell you what I wanted to enable me to order Mantis :D

Certainly some show and tell videos would be an excellent idea. Look forward to seeing some.

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Sat Nov 17, 2012 8:42 am
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Post Re: The opposite of timelapse - very fast motion rig...
My take right or wrong on Mantis vis Dragonframe is that the first appears to be specialist software where as the latter is more mainstream / accessible Ie. hit the Buy button and its ready to use. Convince us otherwise ;)


-------------------------------------------------------


Well, when I bought Mantis last year, all I had to do is connect a drive for each axis, connect the stepper motors to the drive, buy a small power supply unit from RS and bob's your uncle, I got it going, even on my Mac with Parallels.

I found the software OK, but like evereything new, you need to get used to it to get the best out of it. I don't know how well Dragonframe will work, but the help I have had from Gerald, the Mantis guy, has been impressive and worth every penny I spent on his system. You can run up to eight motors, more than enough for mostly everything. I've been messing around with it for one year and I am now building my full rig with six axes of movement if you include focussing. Later on I may add camera roll, and I will still have a spare channel, maybe for a model mover or rotary table.


Edward


Sun Nov 18, 2012 8:40 am
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Post Re: The opposite of timelapse - very fast motion rig...
Actually it would be good to see some user feedback on what dragon frame can do. It strikes me it is a convenient system if you are shooting stop mo animation and want to add basic motion control and it can control DMX lighting if that is your thing.

However - From what I can see, it does not have any form of camera sync which is vital for accurately matching multiple passes. It seems to only play at fixed realtime or stopmotion mode - no offspeed running like 12fps or 48 fps etc. It also doesn't have the ability to record live moves via human controlled input. There also seem to be no editing features other than moving key frames around.

Perhaps they will add more features as time goes on? But it's always going to be hampered a bit by squeezing the interface into an already busy system.

Mantis is a dedicated realtime motion control system with development responsive to users needs. It integrates with professional cameras such as Red and Alexa, as well as with DSLR's.

Regarding demos - do you want to see just the software in action or actually programming a rig? As it's quite a dense program it's hard to know where to start... :)


Sun Nov 18, 2012 4:04 pm
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Post Re: The opposite of timelapse - very fast motion rig...
This is a real nice demo showing how to setup a multiaxis keyframed shot and adjusting keyframe positions to tweak the motion. Its nice that he uses a rig as a "prop" for showing how the program relates to doing an actual shot.

http://vimeo.com/49291544

Maybe something like this showing how to use some of Mantis's features giving us an idea of what its like to use the system. Most of us use dolly/pan/tilt rigs instead of the crane, and some include focus or zoom motors. Give us the impression we know how to use Mantis and we won't be able to stop thinking of shots we're going to want to make with it.


Sun Nov 18, 2012 9:18 pm
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Post Re: The opposite of timelapse - very fast motion rig...
geraldft wrote:
Regarding demos - do you want to see just the software in action or actually programming a rig? As it's quite a dense program it's hard to know where to start... :)

My main interest would be in the interfacing of Mantis with stepper motors / alternative motor configurations with a few field examples of both real time and time-lapse examples.

I am currently creating a six axes system consisting eMotimo TB3 and an Arduimo Uno + Big Easy Drivers controlled by a Dragonframe sketch, I am doing it that way because I have the equipment and the knowledge (just ;) ). What would be the cost of replacing the the DF component with Mantis controlling the steppers / what other information would you need to create a quote.
I am a hobbyist that likes to see things move and have a limited budget that I extend by making / adapting items with a minimal range of workshop tools. If the process of costing / ordering Mantis was more transparent then I think a lot more of us would take a keener interest in it.

Hopefully this topic will draw a few more into the debate :D

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Mon Nov 19, 2012 6:16 am
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Post Re: The opposite of timelapse - very fast motion rig...
Ah bit of debate here so will join in (not having much luck elsewhere :D ) I am probably one of the first people on this forum to pre mote Dragonframe . This isn’t because of any preference more due to the fact I come from a animation background ,set builder so not that glamorous .
Dragonframe is a excellent animation tool all the biggest studios use it too produce films like Paranorman , Frankenweenie . You can magnify live view. You can vector draw on the screen and it will work out timings . Their are extensive lip sink tools but of course all this is totally wasted on a timplapser.
Another big limitation is no real time moves and its a pain. You can potentially tweak every aspect of a move but to run a test shot just takes to long . About 5mins for 200 frames depending on how far the motors have to move each shot . Their is a fella Doug Kropla who as achieved almost real time moves but I can t work out how he’s done it .
The strongest feature Dragonframe as for the timelapser besides the motion control is the cinematography window . In here you can control all aspects of the camera remotely . So achieving spot on exposer and focus is easy .
If I had enough funds I think I would use both Mantis and Dragonframe because both are excellent products and as people have said if you get in touch with Gerald he is very helpful. I think Mantis is probably the only product you could uses if you are a videographer who wants to combine live video with special effects type shots. The ability to record live moves and replay them in any mode is essential for modern motion graphics .
If Gerald was to bring out a slimmed down version that ran on a pad and didn’t rely on a Kflop board I think he would be onto a winner . Think Mark Roberts have a light version of their Flair software that runs on a smart phone great for timelapsers who don’t want to lug tons of gear about .


Tue Nov 20, 2012 3:58 am
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Post Re: The opposite of timelapse - very fast motion rig...
I think after having tried real time moves, I wouldn't want anything else. Most guys here is do this as a hobby, they don't want to spend for a professional "solution", or they perhaps enjoy tinkering with Arduinos and the like, like I did to start with. And I had great fun. But it wasn't getting me anywhere near what I wanted to achieve quickly enough.

I bought the Kessler head, I bought the Omnislider, all fine for simple moves, but not programmable with keyframes and not multi axis as I wanted. Gerald came to the rescue, the price was right, actually even cheap considering that you get something that does everything I need.

You still have to build your own rig though, and it's not as easy as I first thought because I've made lots of mistakes. I wasted my time with the Phidget motors, which come with a planetary gear head 100:1 which has (to me) unacceptable backlash. Luckily I now have a pan tilt focus head with Harmonic drives that has zero backlash and very nice smoothness.

I remember my desperation with the planetary gears until one day Gerald suggested, why don't you bite the bullet and get yourself a couple of Harmonic Drives? It works out more expensive than people imagine, but less expensive than a M Roberts head, obviously they have to make a profit!

But for timelapse you don't need all this accuracy anyway :D


Tue Nov 20, 2012 3:16 pm
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Post Re: The opposite of timelapse - very fast motion rig...
What harmonic drives? Are they some kind of geared stepper motor? I am fixin to repeat your mistake with the Phidgets geared steppers. You can save me a lot of time and money by posting a link to where you got the harmonic drives. Did you get the harmonic drive already attached to stepper motors or did you have to purchase the motors and drives separately? A picture of the P/T head you made with them would also be nice if you don't mind me stealing your design. Thanks.


Sun Nov 25, 2012 10:07 am
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Post Re: The opposite of timelapse - very fast motion rig...
Yes, harmonic drives are basically zero backlash gears. They work differently from planetary gears. They are used in the aircraft industry, robotics, telescopes, CNC, etc.
Mine are tiny compared to the big sizes you can get. These are about 32 times each more expensive than a Phidget geared motor. Since you need at least two, it's only a proposition if you are really serious or fanatical!

I tried finding them second hand, but couldn't, so I bought new. They will last, as they are very well built and have a very robust front ball bearing that takes strong dual axe forces.

I've included a picture of mine, which has a 100:1 reduction (cute, isn't it!) Your motor connects to the pulley, in my case with an identical pulley. I've machined the bottom circular part that bolts to the harmonic drive with 6 bolts. This flat base has a 3/8 tripod thread underneath. The size in this case is like a Nema17 motor, 35mm long (without the top pulley or the bottom circular part)


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Mon Nov 26, 2012 3:46 am
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Post Re: The opposite of timelapse - very fast motion rig...
They are seriously nice units.

Just thought I would pitch in on this one. I also looked quite seriously at these drives a while ago but my budget did not allow. :cry:

Pan/tilt is merciless when it comes to backlash. Woe betide anybody that does not deal with it...... But .. For those that cannot afford ..... there is a simple way to remove backlash completely. You pre- load the gear train and employ counter torque or torque bias.

It's cheap .... like really cheap...... As long as you are prepared to compromise a bit.

As I say it may be of interest to some ..... Hence the post .... but I simply employ a slide on the tilt to ensure the weight is forward of the camera I.e lens heavy. This always ensures a tight mesh. On the pan I have concentrated on getting a sloppy planetary gearbox ( one that is very loose). I then use a low profile needle roller thrust bearing to carry the pan/tilt load and to reduce friction to an absolute minimum. The camera then floats slightly on the pan axis embracing the backlash. I then pre- load in the opposite direction to the one I am headed. (I use a spring that allows plenty of movement)

You then set the torque to oppose the pre-load (i use a controller that allows you to adjust the current) If you get the balance right you can index backwards and forwards with a completely tight mesh. Because of the 100-1 box holding torque/ power in not a problem.

Here is an interesting summary re approaches >> http://motionsystemdesign.com/engineeri ... mark-0399/

Check out the table

Out of interest torque bias is used a lot in radar systems and deep space telescopes. They use two motors in opposition but out of balance

I still want harmonic drives though.... I just need to save harder :D

John

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Mon Nov 26, 2012 10:00 am
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Post Re: The opposite of timelapse - very fast motion rig...
John,
Before getting my HD's, I had a go with antibacklash worm gears, the split-in-half kind which forces the gears to mesh. I had limited success. You have to be very precise in aligning all the shafts and bearings (not impossible) but I found myself spending hours trying to make a success of it. I gave up because my engineering knowledge and machinery is not so advanced. I would've got there eventually, but time is of the essence and also I can legitimately claim these things against tax, etc, so you can see why I cut corners.

But those with patience and technical ability can certainly go for worm gears, albeit they may end up with a relatively large contraption, bearing in mind that you really need a reduction of at least 50:1 (I prefer 100:1) so that means a lot of teeth in the gears (and therefore biggish diameters) to achieve the reduction in a simple manner.

Or go for more precise planetary gears (quite costly, you may as well bite the bullet and get HD's)


Mon Nov 26, 2012 11:23 am
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Post Re: The opposite of timelapse - very fast motion rig...
Ah backlash my favourite . You quickly learn that any gearbox that comes at a reasonable price also comes with a reasonable amount of backlash and when you start panning and tilting rolling it is a problem .
I am also getting the impression theirs different kinds of zero backlash .I consider my rig to have zero backlash buts its hard to measure I do multi pull passes and check alignment by difference blending . Their doesn’t seem to be a problem and I don’t use harmonic gearboxes.
I suppose a timing belt my have a tiny bit of play but not enough to cause a problem . Must admit I find it odd spending a lot of money on a harmonic gearbox then to couple it to a motor with a timing belt which could possibly introduce that tiniest amount of play . If perfection is what you are after would it not be better to directly connect the motor to the gearbox . Or have I miss understood ,this can happen quite easily these days. :D


Mon Nov 26, 2012 11:26 am
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Post Re: The opposite of timelapse - very fast motion rig...
How do you achieve no backlash with your system? Is it really non backlash if you do forward and backward moves?

With a proper timing belt and proper tension, there is no backlash whatsoever. But even if there was some infinitesimal move in the timing belt (which there shouldn't, bear in mind you are meshing half the number of teeth in the pulley at the same time, with belt tension and with a relative low input torque!) this imaginary infinitesimal move would then be divided by 100, as this happens at the input stage, so go figure!


Mon Nov 26, 2012 12:05 pm
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Post Re: The opposite of timelapse - very fast motion rig...
BTW, DISPLACEMENT, I seem to remember we have the same milling machine, the SX2.

I've just thrown away the leadscrews and fitted Acme leadscrews/nuts. They have reduced the mill backlash considerably, almost completely, though not in a harmonic drive perfect sort of way!

I have also fitted digital readouts for the X and Y axes, what a difference all this makes! Now I can enjoy machining parts at last!

It's the bloody clamping of the pieces to the rotary table that I really hate....


Mon Nov 26, 2012 12:16 pm
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Post Re: The opposite of timelapse - very fast motion rig...
Hello Edward yes all my drives are timing pulleys of different sorts depending on the load they are under. And I do believe I get zero back lash . It seemed the most cost effective way as long as you are prepared to quite a bit of engineering yours self . But thats the bit I like anyway and having my CNC makes it easy .So yes I agree timing pulleys are very good !
Yes I have the same mill as you but haven’t converted the lead screws. I may do in the future but to be honest I cant see the point at the moment . The tolerances I am getting seem to be sufficient . I use Mach3 to drive it which as backlash compensation built in and you get digital read outs of the table position too . Very good program actually .
On the clamping side I just tend to use a mill vice and parallels all the time . Suppose we could start a thread on the machines that make our machines but that may be a bit to geek


Mon Nov 26, 2012 1:19 pm
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Post Re: The opposite of timelapse - very fast motion rig...
A thread about machining would be of great interest to me. But I'm pretty geek.

I found a butt-simple way of fighting backlash. The right angle (worm gear) gearboxes I use for lensmotors have a considerable amount of backlash. It doesn't matter in that application because it is only moving in one direction on each shot and its always pushing on the same side of the gear teeth. There are no problems with wind blowing it around like you'd have with a pan-tilt head. There was no reason to deal with their backlash until I got the idea of using two of them for a pan-tilt. The right angle drives have two output shafts going out opposite sides of the gearbox. I can drive an axis with one output shaft while applying a little brake to the other output shaft. The brake resists forces such as wind which would otherwise wiggle the head, but the motor overwhelms the brake when it has to move. You can adjust the brake to pinch gently when there is little wind and have it pinch more if there is more wind or if an unbalanced load is to be moved past its tipping point. It works great.

I am pretty obsessive about my hobby. Ed and Gerald have been really helpful with their advice about harmonic drives. I was lucky enough to get a deal on two identical ones on ebay. Although my worm drives with brakes would work, I just had to try making a P/T with those nice harmonic drives. The plan is to use the toothed pulleys and belts to couple them to some small stepper motors, so thanks for the comments about them too.


Mon Nov 26, 2012 3:28 pm
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Post Re: The opposite of timelapse - very fast motion rig...
Hi

An interesting topic. I have been a big fan of harmonic drives for many reasons.

My first pan tilt head used a worm gear with spring loading to control backlash. But making the spring too heavy creates resistance which limits speed, too little and an uneven load can make the tilt fall over - and under fast moves even the pan can clunk. (All this is worse with heavier cameras.)

For animation and timelapse pre-loaded gears work ok - but to build mechanically it can be rather complex to do well. Another approach is to use straight cut gears with pre-loading but two stages might be needed to achieve sufficent gear reduction in a compact frame. And as Edward found it's not the easiest thing to build.

The beauty of the harmonic drives is most of the hard work is done. A decent integrated support bearing on the output, sealed long lasting industrial quality inside. Very smooth transmission and practically free of backlash compared to most other solutions.

How they work is rather simple once you get it - plenty of info online if you search - but basically a very clever idea which doesn't need many moving parts. They were first used by NASA for their lunar robot vehicle.

Belt drive from the motor works well - despite possible concerns about backlash. Small timing belts can have a tiny amount - but because it's on the drive side of the gear it translates into much less. You can of course get HD's with integrated motors, but then they become rather elongated which may be a concern if you're trying to keep the head compact.

All that said and done - backlash is not always such a problem for certain shots. If the drive is always in the same direction then every pass can still match. The problems come more when changing direction during the shot and when shooting real time. Even with a frictional damping there is going to be a little pause and clunk as the backlash is taken up. (At the start this can be alleviated by pre-loading the move - ie. back it up a little before moving to start.)

As Edward has discovered the pan tilt head is the most important part of the rig - and a good one will last forever... :)


Thu Nov 29, 2012 8:52 pm
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