Motion Control and Motor Drives

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Recommendation for visual tracking system, stepper or servo?

Hi all,

 

I have an application that involves a directional antenna mounted on a pan/tilt device.  There is a camera mounted concentric to the antenna, and the goal is to use the camera to track a small rocket being launched from 1km-2km away so that the antenna always points towards the rocket.  The pan/tilt involves 2 axes of motion.

 

Let's assume the camera can pinpoint the XY coordinates of the rocket from the image.  The more this point deviates from the center of the image (say, 320,240 from a 640 x 480 image), the velocity of the motors should change on the fly to compensation for this deviation.

 

I want to be able to change velocities (positive AND negative) in a loop, without too much hassle.  Currently I'm surveying PCI plug-in boards using the NI-Motion API and also cRIO with the SoftMotion API.  I've had experience programming in both.  I'm a little skeptic about SoftMotion, according to this post:

 

http://forums.ni.com/t5/LabVIEW/Velocity-profiling-with-SoftMotion-Module/td-p/1062345

 

The NI-Motion manual also mentions "velocity override" in Chapter 5, but I don't see this providing velocity changes in the negation direction.  I also would like to avoid using the 9505 and FPGA programming.  Has anyone done a similar application, and can you comment on what NI HW and what type of motors (stepper or servo) you used?Thanks!

 

John Wu

Riobotics Technology Consulting

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我看過這個範例,看起來是可以用的。關鍵是在Load Velocity in RPM這個指令,範例中它是根據一個case被觸發 ... 我需要的是這個指令一直不斷的被觸發,例如每10ms一次,不知道這樣會不會造成一些問題?

 

-John

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