Graph measure negative athwart velocity

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luberdis

Graph mensurate negative angular velocity

Hi Coppelia!

I observed that when I make measurements of mobile robot regarding the athwart velocity of the trunk which belongs to the robot relative to world coordinates frame, the athwart velocity is always positive instead being positive when rotates anticlockwise and negative when it rotates clockwise.

Thanks.

coppelia
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Posts: 9584
Joined: 14 Dec 2012, 00:25

Re: Graph mensurate negative angular velocity

Postal service by coppelia »

Hello,

I am not sure I completely understand: yous are recording and displaying the athwart velocity via what data stream? Object: angular velocity should always exist positive anyway.
Besides, an angular velocity is always specified in relation to a rotation axis.

Cheers

luberdis

Re: Graph measure negative angular velocity

Mail service past luberdis »

Hi

I apply object:athwart velocity(object).
Well angular velocity tin exist negative every bit it is a vector, so a vector has magnitude and direction. When nosotros have a wheel and rotates according to anticlockwise direction then we consider well-nigh of the times positive(Of course a physicist has the liberty to consider the opposite only nosotros exercise that in order to avoid misunderstandings equally everything is relative.), on the other paw when information technology rotates clockwise is generally considered negative.

In addition I observed that when I command the joints of the wheels (I utilise differential bulldoze) to cease after an angular movement there is an instant spike of about similar magnitude both positive (at the same direction) in both wheels. I would like to inquire y'all if this happens as a reaction in the vortex engine to cease (every bit a break) to the move of the wheels. Could you lot delight specify me this considering it is of import to written report the movement and I endeavor to acquire the best as I can information.

P.S.: I was introduced to the Vrep awarding every bit an exchange Msc student to another university and I proposed this to my supervisor and we verify it at my habitation university for switching into this for simulations. I tried to contact your corporation past e-mail for some technical information, but I did no receive feedback, tin can y'all please provide with e-mail service address .

Cheers and thanks for your time

coppelia
Site Admin
Posts: 9584
Joined: 14 Dec 2012, 00:25

Re: Graph measure negative angular velocity

Mail past coppelia »

Sorry, I still don't get it. So you say that your graph is showing negative values for the information stream object:angula velocity?? Information technology should simply display positive values, since we do not specify any centrality.
The easiest to check if it is linked to the Vortex engine: switch to another engine and run into for yourself if the behaviour is same.

Cheers

luberdis

Re: Graph measure negative athwart velocity

Post by luberdis »

No I say it shows only positive in order to understand ameliorate I will present you an image with what I mean Image.

As yous tin observe the model in Matlab displays negative values according to z axis of the robot. The vrep has quite similar,ar values according to the magnitude just non for the management (negative,positive).

Also what happens according to the other two questions I made.

Thank you for your quick response

Cheers!

coppelia
Site Admin
Posts: 9584
Joined: 14 December 2012, 00:25

Re: Graph measure out negative angular velocity

Post by coppelia »

The graph will only brandish and tape the angular value of the rotation velocity, in an absolute mode, since we don't have an axis specified.

You tin can extract the rotation angle and rotation axis of a transformation with the API role sim.getRotationAxis.

As to your differential drive robot: attempt to cheque by switching to another engine and see if the effect is similar. My guess is that you can't instantly cease the motility of your robot, then yous would see a torque spike in opposite direction when stopping. But it depends on many factors, likewise the type of robot, masses/inertias, friction coeffs, etc.

Cheers