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Controlling/Setting of the Torque of a Motor in Robotics Module 2013

Hi all,

I am using Robotics Module 2013.
I currently work on a project about simulation of industrial robots but I have a problem with Robotics Module.

In simulator, we are able to set positions or velocities of motors.
By using this, I have tested my inverse kinematics algorithms and velocity profile tracking.

I want to share a video about it but in fact

I am unable to give a youtube video link.


But now, I am going to obtain the dynamical model of the robot

and I have to control torques of motors in the model.

So, how can I do it?
Is it possible?

Please help me

Thank you

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Message 1 of 18
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Hi dncr,

I know there is a way to calculate the torque of a joint using the joint position and acceleration using the following vi

also this vi calculates coriolis torque.

You can try to adjust the acceleration to get the appropriate torque, which in affect allows you to control the torque

 

hope this helps.

Paolo F.
National Instruments
Applications Engineer
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Message 2 of 18
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Thank you for your answer Mr/Mrs Paolo;

 

I know that VI but I think you miss understand my question.

 

I did not asked how to calculate torques


I asked that how can I apply the torques(which I have calculated some other way - such as adaptive control or robust control etc)

to the motors on the Simulator Display Window

 

I can set positions, I can set velocities but

I am unable to apply a torque or current.

 

Because of unable to apply a torque, I can not move linkages heavier than 1 kgs!

 


I will share a video of my simulation.

http://www.youtube.com/watch?v=Ipt8-BsxqWw

 


In this simulation, joints are controlled by set position and set velocities.

 

But for computed torque control techniques, I should apply torques to the motors and

see the responses of my control algorithm in simulation.

 

I hope I could tell my problem in details.

 

Thank you again

 

Dinçer Saygılı

Acrome Robotics

Istanbul Technical University

ARI-3 SciencePark

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Message 3 of 18
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Hi dncr,

I'm sorry, I just thought that if you were able to calculate the torques you could do a feedback loop until the torque desired was achieved. Or you could find the acceleration that correlates with the torque and use that.

Paolo F.
National Instruments
Applications Engineer
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Message 4 of 18
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Dear Paolo;

 

I tried to explain my problem in that topic with examples.

Please take a look at this subject.

 

Thank you

 

http://forums.ni.com/t5/LabVIEW/Robotics-Simulator-Mass-Problem/m-p/2668991/highlight/true#M794986

 

 

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Message 5 of 18
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Have you taken a look at the help file? This may shed some light on the issue:

 

http://zone.ni.com/reference/en-XX/help/372983D-01/

Applications Engineer
National Instruments
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Message 6 of 18
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Mr Eric;

 

Yes, I have already analyzed the Robotics Module Help.

 

It is beside the point.

There is no information about masses of links

or controlling the torque of a motor.

 

In fact I need to control the torques of the motors as a function of time,

so I can control the robot for a desired trajectory.

 

Thank you for your interest

 

Dinçer Saygılı

Acrome Robotics

Istanbul Technical University

ARI-3 SciencePark

 

 

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Message 7 of 18
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Since you have already calculated the required torques and required time, could you try using the Forward Dynamics VI? Take a look at this reference from the Robotics Help file:

 

http://zone.ni.com/reference/en-XX/help/372983D-01/lvrobovi/forward_dynamics/

 

It seems you will just need to create the torque function from this example:

 

labview\vi.lib\robotics\Kinematics\dyn\torque_function.vit

 

Hope this helps.

 

Robert R. | Applications Engineer | National Instruments
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Message 8 of 18
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Mr Robert;

 

I think you misunderstand the problem.

 

The problem is not generating trajectories for position or velocity.

In fact, I have completed them with my own algorithms by using MathScript.

 

The problem is all about simulating them.

 

The motors can not move heavy links on simulation.

Here is an example project that clarify what the problem is

 

10kgs (unable to move)

1kgs (movable)

 

In this projects, take a look at XML files.

In one of them the mass of yellow link is 1 kgs,

and in the other project it is 10 kgs.

 

If link is 10kgs,

the motor that attached to the joint is unable get the desired velocity due to the link mass.

 

I hope, now it is clear that what my problem is.

 

Thank you

 

Dinçer Saygılı

Acrome Robotics

Istanbul Technical University

ARI-3 SciencePark

 

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Message 9 of 18
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Hi dncr,

 

Perhaps the following example will help you with your problem?

 

https://decibel.ni.com/content/docs/DOC-24599

 

In the example there, it can "Compute the forward dynamics - i.e. the acceleration of the joints - given the input torques."

Rahul B.
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Message 10 of 18
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