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#1
09-04-2014, 03:05 PM
 Melody Member Join Date: Aug 2014 Posts: 26
How to get real time position of a object which is connected to a haptic device

How to get real time position of a object which is connected to a haptic device?

My haptic device is phantom omni

I tried to print it out, it shows [0,0,0] all the time.

I need to read the real time position and then apply different functions based on different positions.
#2
09-08-2014, 03:27 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,471
Do you get changing positions with the following code?

Code:
```import viz
import vizact
viz.go()

sensable = viz.add('sensable.dle')
device = sensable.addHapticDevice()

def printPosition():
print device.getPosition()

vizact.ontimer(0,printPosition)```
#3
09-11-2014, 10:23 AM
 Melody Member Join Date: Aug 2014 Posts: 26
Thanks Jeff.

May I ask how can I get the real-time spring force I applied?
I tried <effect>.getMagnitude(). But what I get is a constant I set in addSpringEffect.

<device>.addSpringEffect( gain=None
,magnitude=None
,position=None
,referenceFrame=None )
Position here represents the effect position, right?

And what is the relationship between magnitude and spring force? In F = k(P-X), magnitude is the max spring force?
#4
09-11-2014, 03:16 PM
 Jeff WorldViz Team Member Join Date: Aug 2008 Posts: 2,471
Quote:
 May I ask how can I get the real-time spring force I applied?
After you've defined and enabled the spring effect you could create your own function that returns the spring effect force based on F = k(P - X). Something like the following:

Code:
```import vizmat

def getSpringForce():

#get effect position and gain.
P = springEffect.getPosition()
k = springEffect.getGain()

#get haptic device position
X = device.getPosition()

#return force
return k * vizmat.Distance(P,X)```
Quote:
 Position here represents the effect position, right?
Yes, the position value you pass in when you define the spring effect is the effect position.

Quote:
 And what is the relationship between magnitude and spring force? In F = k(P-X), magnitude is the max spring force?
The magnitude of the effect force is capped at the magnitude value you define.
#5
09-15-2014, 03:35 PM
 Melody Member Join Date: Aug 2014 Posts: 26
Thank you so much!!!

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