To calculate the Angular acceleration of link. [closed]

asked 2013-04-17 09:45:35 -0600

vedmathai gravatar image

updated 2013-04-17 11:52:39 -0600

Correct me if I am wrong, but isn't AngularVelocity= Torque/ Moment of Inertia. Linear velocity = Force/ mass. Since both

math::Vector3 Link::GetRelativeLinearAccel() const { return this->GetRelativeForce() / this->inertial->GetMass(); }

and

math::Vector3 Link::GetRelativeAngularAccel() const { return this->GetRelativeTorque() / this->inertial->GetMass(); }

are using GetMass() then, both torque and force are being divided by mass to give you linear velocity and angular velocity respectively which I think is physically incorrect. But it has been done even in the setter functions under Link.cc, I don't know if it was wanted it that way. Or I am seeing it wrong.

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Closed for the following reason the question is answered, right answer was accepted by nkoenig
close date 2013-07-23 21:25:18.611321

Comments

Can you post link to specific line of code in bitbucket? This may be worth posting an issue.

dcconner gravatar imagedcconner ( 2013-04-17 10:53:31 -0600 )edit

as @dcconner pointed out, you have misspelled velocity with acceleration

AndreiHaidu gravatar imageAndreiHaidu ( 2013-04-17 11:04:14 -0600 )edit

Thanks for pointing out the mistake in the heading. I have edited that.

vedmathai gravatar imagevedmathai ( 2013-04-17 11:53:36 -0600 )edit

and there is already an issue posted by John Hsu, https://bitbucket.org/osrf/gazebo/issue/607/link-getrelativeangularaccel-is-incorrect. But he was just referring to one of the functions. What I was asking was, why is it at every angular acceleration getter and setter function, only 'Torque/Mass' is used and not 'Torque/Inertia'.

vedmathai gravatar imagevedmathai ( 2013-04-17 11:57:59 -0600 )edit

When we fix issue #607, we'll fix it for all the relevant functions, not just the one listed in the issue details. Feel free to add links to other places that need a fix on the issue page.

scpeters gravatar imagescpeters ( 2013-04-18 00:15:45 -0600 )edit