I need help with moment of inertia

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dkunosic

Newbie level 2 moment of inertia matlab

I hope that somebody can help me with this problem. I do not know how to calculate total momet of inertia for two-link planar arm with the following data:

a1 = a2 = 0.8m
l1 = l2 = 0.5m
ml1 = ml2 = 20kg
Il1 = Il2 = 10kgm2 (moment of inertia relative to the centres of mass of the two links)
Ra1 = Ra2 = 20 Ω
Im1 = Im2 = 0.04kgm2 (moment of inertia with respect to the axes of the two rotors)
kt1 = kt2 = 3Nm/A

ktp = 1
ktp = ktv = 0.4
ζ = 0.6

I need this in order to make comparasion betwen various control schemes in matlab.

Thank you.

Tohu

Full Member level 1 matlab moment of inertia

h**p://scienceworld.wolfram.com/physics/MomentofInertia.html
h**p://www.physics.uoguelph.ca/tutorials/torque/Q.torque.inertia.html
h**p://en.wikipedia.org/wiki/Moment_of_inertia

these links give to you all needing information. I not understand what you have to do. Moment of inertia is a parameter, very like to the kinetic energy, actually this is a directly connect with this energy. Every detail have a three moment of inertia, one for each axes x,y,z. In your case for you will be interest moment of inertia toward the axes of rotation.
If you see second link you will find a formula to calculating it for a solid rotation detail.
After this you can calculate the energy store in to the detail rotating with a speed x, or torque to accelerating the detail with acceleration y.

dkunosic

Points: 2

sstoilov

Newbie level 4 to calculate moment of inertia of a robotic arm

Look at the Ben Sandler's book: "Robotics - Designing the mechanisms for Automated Machinery" - page 318 (and around) is explained how to calculate dynamics for robot/manipulators like SCARA type arms, which I guess is exactly what you need

dkunosic

Points: 2

hanglb

Junior Member level 1 how to calculate moment of inertia

You can look up theoritical mechanics.There are some tables about moment.
Also, If the shape is not regular, you can look up finite element method to solve it.

dkunosic

Points: 2

VVV moment of inertia in matlab

I am not an expert, and I don't even know if your problem can be reduced to my example, but here's my two cents:

Apply the parallel axis theorem:
The moment of inertia about any axis equals the moment of inertia relative to the parallel axis through the center of mass, plus the mass of the body times the square of the perpendicular distance between the axes.

Let's assume the links are as in the figure and we want to calculate the total moment of inertia with respect to an axis perpendicular to the paper, going through point A. I do not know what a1 and a2 are and I am going to assume that l1 and l2 are the link lengths, from bearing to bearing (points A, B, C).

For the first link, the moment of inertia is then:

For the second link, the maximum moment of inertia occurs when the arm is straight (again with respect to the axis through A, perpendicular to the paper)

This is the maximum, with the arm completely extended. For intermediate values, you need to calculate the actual distance from the center of mass of link 2 to point A, as a function of the angle between the two links.

Witt that said, the maximum total moment of inertia relative to axis through point A and perpendicular to the plane of the paper is:

I hope this helps. Otherwise, perhaps you can post a drawing, since I am not familiar with these notations, I more or less guessed them.

Regards,
VVV

dkunosic

Points: 2

newborn

Member level 2 inertia matlab

check out in any college level physix (dynamix) book and solve it. Someone posted a physix book here earlier.

rag_perfect

Banned dkunosic

Points: 2

dkunosic

Newbie level 2 matlab to calculate moment of inertia

Hi,

I found solution for this problem. Thank you very much.

Regards.

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