Smooth Sinusoidal Motion without Gearing, Onboard Buffer/Contouring?

Hello,
My end goal is to have a stepper motor (200 steps/rotation) produce a smooth sinusoidal motion at 1Hz with an amplitude of 200-500 steps. Everything I've read so far has lead me to believe that this is impossible given the 7330 Motion Controller.
My best results were produced when an array of points were created, and used to change the Target Position inside a While Loop. The frequency was varied by changing number of points in the array that represent a complete cycle (an array of 32 data points results in a higher frequency than an array of 64 data points). However, this was not acceptable as the motion at 1Hz was not smooth. I've tried playing around with acceleration, deceleration, velocity, and S-curve Time, but to no avail.
I've thought about using the built in "Load Circular Arc" VI, and just assigning the 2nd motor axis as a dummy output, but this is not a good solution as I will eventually be using all 4 axis of the Motor Drive.
My question: Is it indeed impossible to produce a smooth sinusoidal motion of 1Hz with a 7330 Motion Controller? I realize "smooth" is objective, but the motion produced by the "Load Circular Arc" VI is "smooth" enough.
Equipment/Software:
PCI 7330 Motion controller
MID-7604 Motor Drive
LabView 2009
Any information towards this matter is greatly appreciated. Thank you,
Nick
Solved!
Go to Solution.

Nick,
as it looks like you have already found all possible solutions for your task. In fact arc moves with a dummy axis would be the only reliable solution for your setup. If you can't afford to waste an axis, the only alternative solution is to switch to a 7344, which supports contouring.
Please note, that the 7330 is our low cost solution for basic motion control tasks with stepper motors. Advanced trajectories are not within the scope of this product, so if this is a requirement, please contact your local NI branch. Depending if you have just recently purchased the 7330 or not, they might be able to offer you a hardware upgrade to the 7340.
Kind regards,
Jochen Klier
National Instruments

Similar Messages

How do you create a smooth slow motion

Attached are both the original clip, 2 second long, and 5 times slower clip of the original.
for some reason the slow motion is not smooth. is there a way to make it smooth?
thanks
arikw

If your camcorder can shoot 60p, import that clip, then right-click it and Modify > Interpret. The frame rate should show up as 59.94, go ahead and change that to 29.97 and then put the clip on the timeline. This should have the result of doubling the length of the clip and providing silky smooth 50% slow motion (without adding Speed Change, leave that at 100%).
Just picked up a new GoPro Hero 3 White, and it has 720p60 and I tried the above and it looks nice! The more expensive GoPros offer 720p120 and that should yield excellent 25% slow motion using the same methods. With the waterproof housing and wide angle lens, you could get right up close to that waterfall!
Thanks
Jeff

How to generate digital pulses to run stepper motor in a sinusoidal motion profile using NI DAQ 6229 card

Hi,
         I need to make a stepper motor undergo rotary oscillation with a sinusoidal motion profile. As it nears the extreme points it should decelerate and finally slow down to zero velocity and then it should reverse direction and accelerate until it reaches the other extremity where it should slow down and stop and reverse direction and repeat this motion.
        The hardware is NI DAQ 6229 and the stepper motor can be controlled using digital Hi-Low (1,0) pulses. For each high pulse(1's) the motor turns 1 step. I am able to generate a analog sine wave and convert it to digital data using Analog-to-Digital.vi But i am not able to convert the digital data to a stream of 1's and 0's in the correct sequence to get the sinusoidal profile with the amplitude and frequency i require.
        The direction of rotation can be changed by giving a pulse to another input of the stepper motor. So only half cycle of sine wave needs to be generated and it can be replayed after changing the direction to get the full sinusoidal profile.
Any ways of making this approach work or any new approaches to this problem would be helpful. Thank You.
Regards,
Prabu.
Solved!
Go to Solution.

Hi,
   I finally figured out a way to do it. The analog sine wave is converted to digital and sampled. Consecutive values are compared and if the least significant bit(LSB) changes then a pulse is sent to the stepper motor to turn one step.
I have included the sub-VI's that accomplish it for the particular stepper motor and connector block i have. The front panel of both sub-VI's are quite messy but the block diagrams should be much clearer. The sub-VI's get their inputs from a third VI which i have not included. So take a look at the VI connector panel to figure it out. Hope this helps. Kinda messy but worked out fine in the end for my application.
Thanks again for all the help. I appreciate it very much.
Regards,
Prabu Sellappan
Graduate Student
Aerospace and Mechanical Enggineering
University of Southern California
Attachments:
start motor test waveform dtest.vi ‏73 KB
sine profile generation subVI.vi ‏41 KB

Smooth Slow Motion from 50 fps Clip in 50 fps Timeline

If I want 50% smooth slow motion from a 50 FPS video clip, I would normally ask PP to interpret that clip as 25 FPS - that works great.
If however I import the 50 FPS video clip and interprett it as 50 FPS, I would have to set the speed of the video clip in the timeline to 50% to get the same level of slow motion.
The question is - when I follow the latter method, does PP create new frames for the slow motion or is it clever enough to use all the frames from the original 50 FPS video clip? to put it another away, does PP always generate NEW frames for slow motion or does it try to use the frames we are attempting to ignore?
I've done some basic tests and so far I can't see any real difference between the two methods. This leads me to beleive PP is effectively using all of the original 50 frames when the 50 fps video clip is imported into a 50 fps timeline and then slowed down in the timeline by 50%. - if this is the case, well done PP!!! If this is not the case, then it would be a welcomed enhancement in future releases.
I guess what you are all wondering is why would I want to import a 50 fps video clip into a 50 fps timeline and then slow it down in the timeline - well, as a wedding Videographer, it is simply because some parts of the video need to be in slow motion and other parts like messages and speeches need to be interpreted at normal speed. If playback in the timeline is at normal speed, i find it simpler to slow down the "Walking Down the Isle" clips rather than having to speed up the speeaches and messages.
In short, when importing 50 fps video for smooth slow motion, are both the following methods equally effective in terms of smooth motion?
Method 1: Import the 50 fps video clip into 25 fps timeline
Method 2: import the 50 fps video clip into 50 fps timeline and set the speed of the video clip in the timeline to 50% - I'm assuming PP does not generate new frames and gets them from the original 50 fps file instead..
To put it another way, does PP ALWAYS attempt to generate new fromes when slowing down video in the timeline? When extra frames are available in the original video file, does PP try to get the extra frames from that file instead of generating new ones?

I recorded 2 video clips of the same scene. The camera was panning from right to left.
First video clip - recorded at 25 fps
second video clip - recorded at 50 fps
Both video clips recorded at the same panning speed of the same scene.
1. If I import the 25 fps video into 25 fps timeline and slow it down by 50%, the exported video looks jerky.
2. If I import the 50 fps video clip into 25 fps timeline, the exported video looks smooth motion.
3. If I import the 50 fps video clip into 50 fps timeline, slow it down in the timeline by 50%, and export the video as 25 fps then the result is still smooth motion.
I've only done the experiment once and may have to repeat to be absolutely sure.

Is it possible morphing in motion without plugins?

Hello:
I´d like to know if is it possible do a morphing in motion without external plugins?
Thanks a lot.

hi,
no not possible in Motion without plugins. Although not the same there's no substitute for a dissolve and a couple of clever masks.
adam

Can you still use soft motion without the scan engine on crio?

Where are the trajectory generator property and invoke nodes in softmotion for LV 2011?
These functions are not longer found in the pallet? Are they no longer supported?
All the new soft motion examples are using the scan engine. Can I use soft motion without the scan engine????
Steve
SteveA
CLD
FPGA/RT/PDA/TP/DSC

Hi Ian,
I apologize that this wasn't stated in the release notes. While your code should have upgraded without breaking, the release documentation should have mentioned that the advanced trajectory genertor functionality is no longer supported. If you still want to use the trajectory generator functions, they are still shipped with SoftMotion, they are just not on the palette. I have attached a zip file that has 4 .mnu files that will get them on the palette. To install these, do the following:
Close LabVIEW
Make a copy of the following directory: C:\Program Files (x86)\National Instruments\LabVIEW 2011\menus\Categories\VisionMotion\_nism. In case something goes wrong, we will want to have a copy of this directory so that we can replace it.
Copy the 4 .mnu files from the attachement into the above _nism directory (the original, not the copy). If it asks you to replace any of the exisiting files, please do. You don't have to copy the readonly.txt file.
Start LabVIEW. You should know have the trajectory generator functions in your SoftMotion Advanced palette.
Keep in mind that we no longer support these functions. This means that they are not tested in new releases and any bugs will likely not get fixed.
I would recommend that you use the new API for any new designs. You can still get most of the functionality of the old API but without the complexity. If you want to generate setpoints at 5ms then you will run the scan engine at 5ms. This is certainly easier than having to do the timing yourself, but it does take away some control from the user. If you give me a brief overview of what you mean by synchronization, I will let you know the best way to do it with the new API.
Thanks,
Paul B.
Motion Control R&D
Attachments:
_nism.zip ‏4 KB

Onboard buffer size

Hi, can anyone tell me the difference between the "buffer size" and "onboard buffer size" under the DAQmx buffer>>output property?
Thanks,
David
www.controlsoftwaresolutions.com
Solved!
Go to Solution.

OnbrdBufSize - is the fast memory every DAQ card has to store the acquired data. It's like RAM in the PC. For example here you find that the NI PCI 6120 has 128MB of this memory which will equal to some amount of samples the buffer can store (this number you will read). This said it also explains why you can read and not set this property.
Output.BufSize - Before you start data acquisition software buffer is defined based on the task you perform. I think it just allocates part of the fast memory of the DAQ card. The reason why the buffer is set (either by the user or automatically) is to have defined memory space for each task. Imagine you have more tasks using the card and each of them needs some memory of the card - if I am wrong correct me somebody.
If your acquisition is finite (sample mode on the Timing function/VI set to Finite Samples), NI-DAQmx allocates a buffer equal in size to the value of the samples per channel attribute/property. For example, if you specify samples per channel of 1,000 samples and your application uses two channels, the buffer size would be 2,000 samples. Thus, the buffer is exactly big enough to hold all the samples you want to acquire.
If the acquisition is continuous (sample mode on the Timing function/VI set to Continuous Samples), NI-DAQmx allocates a buffer equal in size to the value of the samples per channel attribute/property, unless that value is less than the value listed in the following table. If the value of the samples per channel attribute/property is less than the value in the table, NI-DAQmx uses the value in the table.
Sample Rate Buffer Size
No rate specified 10 kS
0–100 S/s 1 kS
100–10,000 S/s 10 kS
10,000–1,000,000 S/s 100 kS
>1,000,000 S/s 1 MS
LV 2011, Win7

Techniques for smooth continuous motion in a game

Hello all,
I'm working on a brick-breaker variant and all is going well except for the motion of the ball-- it isn't as smooth as I'd like. I've done some reading on the subject and have come away with two promising techniques for smooth continuous animation:
1. Use time based position update functions rather than frame-based. This basically allows you to cheat the SWF's FPS setting and make a certain object move more fluidly without jacking up the entire movie's FPS. This is handy and does have a dramatic effect, but it also costs much CPU and/or battery power to process so it (might) not be suitable for continuous motion. It is better left to tweens and other animations that are both short and critical. Also, I found that in order to get the ball moving at a reasonable speed for difficult gameplay I had to either lower the time delay or increase the velocity modifier to the point that the ball appeared to half-vanish much of the time (presumably) because it was getting too far ahead of the movie's frame renderer. As such, this method really isn't suitable for managing continuous core gameplay mechanics.
2. Convert velocity modifiers to floating point values rather than integers. This worked very well to smooth out the motion a bit, and has had no adverse side effects so far as I can see. It doesn't quite get the ball to the level of smooth animation I'd like, however.
Currently my movie's FPS is set to 45 and I'd prefer not to go any higher than that if possible. With floating point modifiers and 60 FPS everything is very smooth, but I am wary of using an FPS setting so high, particularly as this is eventually going to be a mobile app and therefore battery life is a consideration. Does anyone know any more tricks to smooth continuous, game-mechanics-centric motion?
Is there perhaps any magic that can be worked with the new Stage Video API and/or any other hardware acceleration offered by flash player/AIR? Is Stage Video even usable in iOS and/or Android apps created in Flash CS5?
Thanks,
CCJ

What was the Bit-Rate of your Exported MOV file?
Good luck,
Hunt

Smooth Slow motion - THIS IS HOW !

Just thought i'd throw this in to try and give back a little to these boards.
I have seen slo motion come up quite a bit .
I work with alot of action footage and beat match soundtracks so speed changes are important to me!
I work in DV PAL - this should still work for NTSC!
Change the speed of your clip in FC via any one of the 3 methods that are available.
Anything below 50%starts to look choppy on the standard settings
Double click on the clip - go to the viewer -that now references the clip to be retimed - click on motion tab - go to motion blur and check the box
Here is the trick - set motion blur to ZERO and resample 16 or 32 times
render away.
voila !- pretty good smooth slo mo that can get down to as low as 20% and still look pretty good!

Oh James you beat me to the response.
I just tried the OPs technique on a wide shot of a baseball double play @ 40% slowmo. It looks much better than the choppy slo mo that I would have had to settle with. I purposely chose a wide shot because I wanted to see if the blur would make a distracting visual difference. It does of course on a wide shot, (at least for my eye) but I bet on medium and clos-ups it's a true gem.
Thanks Oz for the post

Decent slow motion without artifacts?

I can't get decent half speed slow motion in AE CS6. Frame blending looks horrible with all the double contours in fast moving objects, and pixels motion looks much better motion wise, but introduces horrible motion artifacts. I also tried Pixel Motion using the Timewarp effect to have more control over tweaking it, but no matter what parameters I change, I still get the artifacts. So it looks like After Effects by itself doesn't have a good way to do slow motion that looks great, at least not for the footage I'm using.
Are there any other filters I can try, whether in AE or 3rd party that will go a great job?
Thanks,
Sebastian

As Rick said, blaming it on a specific plug-in/ feature is kinda missing the point. Half the magic happens during shooting. If I knew I'd want to slow things down, I'd get the camera that would offer the highest framerate and least compression, even if it means an expensive rental of an ARRI camera. If that's not possible then you'll have to make do with what you have and try to fix it in post. Using a sophisticated tool like Twixtor no doubt is always an option, but many times it starts with simpler things like trying to reduce block artifacts or evening out color. Such basic stuff often helps the algorithms a lot. The same as you would when doing keying. Also you can always try to mask specific parts and slow them down in separate pre-comps. It may give alignment issues, but if you want to do some sky replacment or keying, it would be acceptable to proceed this way...
Mylenium

How about using a 60fps video for a smooth slow motion effect in a 30fps project ?

Hey all,
I happen to have a video camera that is able to shoot either in 720p/60fps or 720p/30fps.
As you guessed it, 60 fps mode is very useful for action sports when you want to do some slow motion effect running very smoothly.
I have few questions I would love to be answered, and I was not able to find answers till now.
Here they are :
1/ If I want my final video file to be, let's say, 25 fps, is it mandatory that my project is 25 fps too ?
What will happen if I do a 30fps project and that I export to a 25fps file ? Does Premiere simply remove some extra frames ? Or will it lead to a longer video ? What consequence on the final result if frames are removed ? I mean, will I be able to see any difference or will the difference remain theorical ?
2/ Let's say I have both 30fps and 60fps videos. I set my project to 30fps. If I import my 60fps video to the timeline, it will be adjusted to 30fps and some frames disappear to keep the duration the same. Okay, this is clear to me.
But now, what if I import my 60fps to the timeline, but set the speed to 50% ? Will Premiere apply the 50% to the original file (therefore I should have all the frames displayed on the timeline : 60/2=30 fps), or to the 30fps-adjusted file of the timeline, leading to some jerky footage?
3/ If I want to use my 60fps for slow motion purpose in my 30fps project, would it be a good idea to right-click on this file in the project windows, going to the "modify" menu to set the image frequency to 30fps ?
Because while doing so, if I drag the file to the timeline, I noticed it would last 2 times longer (resulting in a slow motion video) Does that mean that ALL the frames of the original video are displayed ? Can someone tell me what exactly does Premiere ?
I would be very grateful if someone could tell me what are the correct settings to chose in order to realise the best slow motion videos as possible.
Thanks in advance !

With due respect... this does not answer my question and does not help me that much , but anyway, thank you for the very constructive answer ^^.
I'm not sure I would even have considered doing this by myself...
I hope I do not get this kind of answer because you feel like my question was silly or unpolite... To my mind this was a pretty serious question.
Shooternz, next time you need to go 150 km far away from where you are, go by feet rather than with a car, I'm sure you will have plenty of satisfaction too. Just cross the fingers for you not to be in a hurry while it's raining outside.
Well, I may be naive but i thought some experts already had the answer to this (I guess I'm not the only one who intend to do some slo mo), and would have been kind enough to share this knowledge with me. That's what sometimes happens in communities.
Please note I do not intend others to do the job for me, I'm just asking if someone already knows the answer.
I asked this question because I couldn't find any documentation about this, and I guess asking on internet was the next step, as testing would be like the last resort, being very time consuming.
It was easy to check the effect of dragging a file to the timeline to see if it played normally or not, but it's definitely not to count and compare each frame of some sample file to find if some are lacking, or have been doubled or what....
I assume I would be very happy with just a simple theorical answer either...
So once again, if someone already has been into such questions, I would really pleased him or her to share or report what they experienced. Thanks in advance.

Smooth Slow Motion

I am looking for a way to create 50 percent slow motion based on odd and even fields. Instead of replicating the odd or even field to make a 15 frames per second, jittery, slow motion, I want to separate the odd and even field, and then interpolate the missing half frame, thus producing a 30 frame per second smooth motion clip that is based on the 60 half frames per second frame rate of video. I know this can be done because Premiere does it automatically. Note: I am not trying to make smooth motion where there is a half translucent image of the preceding frame always on top of the current frame.

Okay, I think Graeme Nattress wrote a plugin to do that, but here's a way to do it in FCP...
Cut your clip on V1 and V2, slow each down 50% with no frame blending. On each clip put the de-interlace filter, on V1 take it from field 1, on V2 take it from field 2. Now apply the blink filter and set it for 1 frame on and 1 frame off. This way it will take first one frame from V1, then one from V2, etc...
Mind you this is a lot of monkey motion, but it should give you the effect you are looking for.
Try it, post back...
Patrick

Smoothing combined motion, pan + truck-in

Hi
I know there's been some talk on this before, but I couldn't find an answer to my problem.
Smoothing a pan is easy, by using the beziers in the canvas window. And creating a smooth zoom by itself aswel, though this works differently as I can (so it seems) only rightklick the keys and turn them into 'ease-in / ease-out, or smooth or somthing.
But the problem is when I run a combined motion, like a pan and truck-in, I can't find a way to combine them into one smooth movement. The default smoothing of both ways (the truckin and the pan) isn't synchronised.
I wonder if there's a way to put both 'hard' movements in a clip or something (like in 3D) and smooth that, might give the same result.
Or any 'free' plugin I could use ?
Thx
Jan

About a year and a half ago, Tom Wolsky posted the following to a thread that isn't on the server now:
"Let's say you're zooming into a picture. You're starting say a scale of 20% centered on the screen and you going to scale up to 100%, and as you zoom in (scale) you want to move to the upper right corner of the image. Scaling takes place around the anchor point. The anchor point is normally the center of the image. As you move toward the upper right you're actually scaling around a point that's moving farther and farther away from where you're going. This causes overshoot, especially if the scale and center values are eased. (Scaling is not exponential anyway so this exacerbates the problem.) If you animate the anchor point to move opposite the center point, the scaling will continue to happen around the anchor point, which is now moving with you toward where you're going. It'll give you a bit better motion, but you still have to give yourself a little wiggle room.
"Let me give you some numbers. I'm starting with an image that's 3600x2670. At it's start the image is centered and scaled to 24%. I can't go all the way to 20% because I'll get overshoot on the start when I put on easing because scale is logarithmic, while center is arithmetic. At the end of the motion the image is scaled to 100. It's center is now -1335, 932. (Again because of overshoot I can't go much closer to the edge.) Easing is set for center and scale, and as I'm sure you've seen you get the image sliding off the screen even with leaving the slack that I did. Now add the anchor point animation. Set the start keyframe at 0,0 the same as the center point. Set the end keyframe to 1335, -932, the opposite of the center keyframe and you'll get a motion that stays in the screen. If you could set easing for the anchor point it would be even smoother, but that's not practical in the FCP interface. You get a little snaking effect at the end. All in all pretty inadequate for good motion control.
"I tried it Motion as well. The first problem is the application can't handle the image at full resolution. It could do the movement with scale animation and a motion path behavior. It was kind of adequate, but easing on the scaling was pretty poor and didn't achieve good results.
A major issue in both applications is the the scaling starts quickly and gets slower and slower. This is because of the lack of exponential scaling, and until this is addressed neither application will be more than barely adequate at best when it comes to large scale motion control. Basically neither of them are acceptable for professional work on large format, large scale images. I won't even go into how totally inadequate FCP is for easing stop and go motion."

Smoothing slow motion

Hi everyone. I'm using fcp7 and I do skateboarding videography. I'm using a Sony PD170 at 29 frames per sec. When I add a slow motion to a clip it doesn't look really clear, I'm slowing it down 65%. Is there an effect or something that I can add to it to make it smoother? Thanks for your help.

I'm using fcp7 and I do skateboarding videography. I'm using a Sony PD170 at 29 frames per sec. When I add a slow motion to a clip it doesn't look really clear, I'm slowing it down 65%. Is there an effect or something that I can add to it to make it smoother? < </div>
We see this post from-- interestingly, skate auteurs-- often so there is some searching you can do to discover past threads.
The issue is probably your shutter speed, not the number of framesper seconds. The 170 can only shoot NTSC at 29.97fps. Fast action requires more frames per second to allow more descreet slices to spread out. But if you were shooting at the default shutter of 1/60th second, your skater has moved a great distance while the shutter is open creating image/motion blur that cannot be removed.
If you were shooting at, say, 1/250 or 1/2,000th second, your individual frames would be crisp and you might be able to separate the fields out from the frames for twice the number of discreet slices of time at the cost of the loss of half the vertical resolution resolution, only half of the horizontal lines would be available in each field.
bogiesan

Smoothing keyframe motion

I'm playing with curving/beliziar keyframe motions for the first time. I'm working in FCP5.
I have one video clip, scaled to 40%, it starts on the left side of the screen,
moves to the center, then goes straight up and off the top of the screen.
No problem doing it with "hard" motions.
But, how do make it into a curved motion...meaning instead of going hard
straight to the center of the screen and then up, as it's moving towards
the center of the screen it starts to smoothly curve upwards so it's not
a hard hit in the center and then up,...but more like a swoop up.
I've tried adding a SMOOTH to the centering keyframe but it won't let me,
and I'm not changing scale during the move.
Any input would be appreciated. Thanks.

right click or control click on your center motion point in the canvas and select "linear". It will change to a bezier point.
N

Smooth Sinusoidal Motion without Gearing, Onboard Buffer/Contouring?

Similar Messages

Maybe you are looking for