Eric Ragnarsson

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These are questions asked by Eric Ragnarsson

Hi

I have crreated a transfer function of a rather complex system using TransferFunction() and recived a transfercundtion of a rather high order (n=10). However due to the kinematics of the model I know that is is posible to expres as an second order transfer function.

So I have been locking around Maple for a function that can help me reduce or approwqimate the transfer function as a sencond order but I have not found anything.

Is there a way to reduce/approximate an n order transfer function to a second order transfer function?

Mvh

Eric Ragnarsson

 

Hi

I am trying to implement normally distributed noise into a maplesim simulation. I thought this would be done most easily thru adding a modelica custom component. There are some examples to go on on the web however Modelica are not really good at explaining there implementation. 

The code for my implemented block can be seen below. 

 

model Noise2
    import MBI = Modelica.Blocks.Interfaces;
    import MBN = Modelica.Blocks.Noise;
    import MMD = Modelica.Math.Distributions.Uniform;
    
    output MBI.RealOutput out annotation (Placement(transformation(extent={{100,-10},{120,10}}))); 

    inner Modelica.Blocks.Noise.GlobalSeed globalSeed(fixedSeed=42);
    
    MBN.NormalNoise generator(samplePeriod=0.1,distribution=MMD.density(0, -1, 1));

    
    Real y(useGlobalSeed=true, useAutomaticLocalSeed = false, fixedLocalSeed=false, startTime = 0);
    
equation
    out = generator.y;
end Noise2;

 

However this results in the following error

Argument 1 must have integer[4] data type

 

Due to my inexperience with Modelica, I don't even know were to start searching for the error. So I turn to this wonderful community in my hour of need, How do I implement normal distributed noise in maplesim?

Mvh

Eric Ragnarsson

Hi

I have created a robot ar with p starting position X, Y, Z and a spring that connects to the robot end effector with a spring that is L long. I have exported this simulink model to an FMU inorder to use it in python. 

Is it posible to change the value of X, Y, Z and L using pyfmi before using it in pythuon and if it is, then how?

 

Thanks again for youre time and help. I know that this is not exaclyt inside the expertise of this fine comunity but have no were else to go.

Eric R

Hi

I have created an model of a UR5e robot complete with mass and inertia however I have a problem with implementing the viscus friction. I have the viscus friction values for each of the joints calculated from another program, I just need to implement them.

 

Mvh

Eric Ragnarsson

Hi

I have constructed a model of an UR5e in maplesim with the hop to be able to test my controller writen in python on it. 

I hope to be able from the model to

  • Enter a tourqvalue for the joints.
  • Extract joint angles, joint velocitys as well as the forces and tourqes that affects the end effector.
  • (If posible) visualize the sumulated robot arm so I can se that the motion reflects that of the real robot arm.

the simulated robot arm 

The question is how to best do this in a semi realtime way?

I have been looking into generating a FMU but if there are other ways to do this, then I am open to ides. 

The contorller is based on a haptic algoritm for connecting two robot arms and I will only get one robot arm due to prise and space constraints.

This means that I will reseave realtime information from the real robot arm into my python controller that then i supose to take inforamtion from the simulated arm and with information from both arms calculate the tourqe values for both arms joints. 

 

Thanks in advance for all youre help

Eric Ragnarsson

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