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Thread Subject:
how can I get velocity and acceleration from angular position signal.

Subject: how can I get velocity and acceleration from angular position signal.

From: Hiba

Date: 14 Jun, 2010 15:15:23

Message: 1 of 5

Hello everyone
I would like to know the best Matlab function I could use in order to get velocity signal and acceleration acceleration from only the angular position signal.
I kbnow that theres' methods like gradien, diff, but I don't get good results
It's so important to use a function that could help me a velocity and acceleration signal, as precisely as possible.
I appreciate your help.
Regards
Hiba

Subject: how can I get velocity and acceleration from angular position

From: dpb

Date: 14 Jun, 2010 15:45:23

Message: 2 of 5

Hiba wrote:
> Hello everyone
> I would like to know the best Matlab function I could use in order to
> get velocity signal and acceleration acceleration from only the angular
> position signal.
> I kbnow that theres' methods like gradien, diff, but I don't get good
> results
> It's so important to use a function that could help me a velocity and
> acceleration signal, as precisely as possible.
> I appreciate your help.
> Regards
> Hiba

One can try to fit the displacement signal and then analytically
differentiate; how well it will work will, of course, depend on how
noise-free the measurement is, how small the time jitter in the
measurement and how good the interpolating function models the
underlying actual movement.

Depending on the rates, some filtering might be beneficial; whether it's
possible at all depends first at a minimum, on the quality of the
measurement.

--

Subject: how can I get velocity and acceleration from angular position signal.

From: James Tursa

Date: 14 Jun, 2010 16:34:04

Message: 3 of 5

"Hiba " <hibahage@hotmail.com> wrote in message <hv5h2a$sil$1@fred.mathworks.com>...
> Hello everyone
> I would like to know the best Matlab function I could use in order to get velocity signal and acceleration acceleration from only the angular position signal.
> I kbnow that theres' methods like gradien, diff, but I don't get good results
> It's so important to use a function that could help me a velocity and acceleration signal, as precisely as possible.
> I appreciate your help.
> Regards
> Hiba

You might try to use a Kalman Filter for this.

James Tursa

Subject: how can I get velocity and acceleration from angular position signal.

From: Roger Stafford

Date: 14 Jun, 2010 17:26:05

Message: 4 of 5

"Hiba " <hibahage@hotmail.com> wrote in message <hv5h2a$sil$1@fred.mathworks.com>...
> Hello everyone
> I would like to know the best Matlab function I could use in order to get velocity signal and acceleration acceleration from only the angular position signal.
> I kbnow that theres' methods like gradien, diff, but I don't get good results
> It's so important to use a function that could help me a velocity and acceleration signal, as precisely as possible.
> I appreciate your help.
> Regards
> Hiba

  If you are talking about an object's position in space, even in the two-dimensional xy-plane, knowing only an angular position is not sufficient information to determine its velocity and acceleration. You need to have some kind of information about the object's distance from the point with respect to which the angle is being measured.

Roger Stafford

Subject: how can I get velocity and acceleration from angular position signal.

From: Hiba

Date: 16 Jun, 2010 10:01:24

Message: 5 of 5

Hello everyone
thank you all for your answers
In fact, i'm working on a robot of 6 degree of freedom, and I can get the joint position. I'm using the functions ''butter'' and ''filtfilt'' to filter this signal forward and backward by using a ''butterworth'' filter.
and then I have to get the signal of the velocity from the filtered signal. Any suggestions for an analytical equations to differentiate/derivate this signal. Gradient and diff are not suitable in my case.
I have to do the same to get the acceleration.
Thanks in advance for your reply
Regards
Hiba

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