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DavidKhan1-Visitor
1-Visitor
September 27, 2013
Solved

S profile for Servo motor

  • September 27, 2013
  • 1 reply
  • 26466 views

Hi all

Could any one help me to make a velocity profile for servo motor which is S profile.the only information i have is that of thetha (position).The total angle rotated by the servo motor is 1800 degree and this angle is covered in 6 seconds.The starting time for this motor is 6th second of simulation and ending time is 12th second.it doesnot start from zero.

thanks.


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Best answer by TomD.inPDX

Let's start here. This is a user defined profile. It has 5 entries. The 6 second delay... the ramp... the hold... the decel ramp... and the final delay.

Note how "t" is used in the expressions because the current value of "t" must be considered to use them in calculations (same with angle for position profiles).

Unfortunately, I cannot find a way to show more datapoints on the graph. It is a bit misleading. If you look at the formulas, and the time domains, you will see where the ramp actually starts and where it ends. You can tweak the position of the "=" sign to fine tune when these milestones are actually hit. It does make a difference in relation to your frame settings during the analysis.

Plot these and see if you get the analysis to run. Remember to use kinematic on the analysis type. Set the time for 19 seconds and I recommend a frame rate of 25 <<== this is so the time will match a video capture at a frame rate of 25. Options are 25, 30 or 50 in the play dialog.

MotionProfile_velocity.PNG

1 reply

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TomD.inPDX17-Peridot
17-Peridot
September 27, 2013

Use the user defined profiles.

I am not sure I understand "S" profile, however... from T6 to T12, that do you want the motor to do?

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DavidKhan1-VisitorAuthor
1-Visitor
September 27, 2013

An S profile or sinus profile is the advanced form of traphezoidal profile.which lkooks line the profiles shown in the pictures attached.Picture 1A is the S curve and 1B is the taphezoidal curve.the second picture is the profile mentioned here http://communities.ptc.com/docs/DOC-3546#comment-11213 by Antonius Dirriwachter

while the first picture has taken from http://www.pmdcorp.com/news/articles/html/Mathematics_of_Motion_Control_Profiles.cfm

s+curveee.gif

cos_power_motor_curve.JPG

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TomD.inPDX17-Peridot
17-Peridot
September 27, 2013

The one challenge with velocity and acceleration profiles is controlling the total revolutions. In these cases, the revolutions is simply a result so no one really knows where it will stop without some other calculations. How critical is the 1800 total revolutions? For this we might have to consider the "position" profile in order to fit the other 2 curves appropriately.

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