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Hello,

I could obtain the simulation of my multibody with kinematic closed chain (CKC).

However, it seems that from a specific time (around 12s) in my model I believe that I have some numerical instabilities. Indeed, I could compare my simulation results with another mulbody software. I obtain the same simulation until 12s and after in MapleSim, it appears many perturbations as you can see on the figures belows.

So, I think that I tune the numerical solver. This numerical solver must solve DAEs equations since my model contains 4 kinematic closed loops.

If i read correctly the help menu, there are the following methods to solve the DAEs :

- use specific DAE numerical solver (3 differents solvers are used : ck45 method, RKF45 method and Rosenbrock method

- use reformulation equations techniques (Baumgarte, Projection) which can be associated (I believe) with a classic solver like (RK4).

For the moment, I have obtained my results with the rosenbrock solver with error absolute : 1.0*10^(-4) and eror relative :error absolute : 1.0*10^(-4) 

Do you have some ideas or advices so as to find a better method to solve my multibody systems with kinematic closed loops ? This method should  prevent the creation of numerical instabilities.

Thanks a lot for your help

 

Hi,

I am trying to plot only the real part of the values obtained from the MapleSim model.  Probably there is a Modelica function to get only the real part of the values, but I am unable to find it. Could you please have a look at the code and let me know what I should do to solve this problem?

Best

Onder

 

The code is: (I want to plot the real part of R2)

 

model IKTest

parameter Boolean switched = false;
parameter Modelica.SIunits.Length L1 = 0.100;
parameter Modelica.SIunits.Length L2 = 0.102;
parameter Modelica.SIunits.Length L3 = 0.5;
//parameter Real c; //Complex number
//parameter c;

Modelica.Blocks.Interfaces.RealInput u[3]
annotation (Placement(transformation(extent={{-140,-20},{-100,20}},rotation=0)));
Modelica.Blocks.Interfaces.RealOutput y[3]
annotation (Placement(transformation(extent={{90,-10},{110,10}},rotation=0)));

Real Tx = u[1];
Real Ty = u[2];
Real Tz = u[3];
Real R1 = y[1];
Real R2 = y[2];
Real R3 = y[3];

equation

R1=atan(Ty/Tz);
R2=(acos((L1^2+L2^2-(sqrt(Tx^2+Ty^2+Tz^2))^2)/(2*L1*L2)));

//2*Modelica.Math.asin(1.0)
//R3=R2.re;

annotation (uses(Modelica(version = "3.1")));
end IKTest;

with(plots):

a:=polarplot(3-3*cos(theta),theta=0..2*Pi):

c:=plot((3*sqrt(2)+3)/2 + ((-3*sqrt(2))/(-3*sqrt(2)-6))*(x+((3*sqrt(2)+3)/2)),x=-10..10):

display(a,c,view=[-10..10,-10..10]);

 

a:= is the polar plot of the cardiod (3-3cos(theta)


In order to plot the tangent line to the cardiod in theta= 3Pi/4, I find the point (x,y) in rectangular coord x=(3-3cos(theta)cos(theta) and y=(3-3cos(theta)sin(theta); then I find the derivative of dx/dy=

[(3-3*cos(theta)*cos(theta)+sin(theta)(3sin(theta)]/[-(3-3cos(theta)sin(theta)+cos(theta)(3sin(theta)]and from here I get the slope.So I can plot c:= tangent line to the cardiod in 3Pi/4.

How can I avoid having to convert everyting to rectangular coords, and plot the tangent line in polars?

 

 

Hello,

I have a question concerning the initial conditions.

One interest of MapleSim is to enable to model a multibody systems with different kinds of coordinates : namely relative and absolute coordinates.

For a complex system, it seems to me that the determination of the initial position is not an easy task.

Consequently, I wonder if it is possible to determine the initial positions for the system in absolute coordinates thanks to the knowledge of the initials positions in relative coordinates.

In other words, I have already determined the initial positions of my system in relative coordinates but as I would like to simulate my system with absolute coordinates. I wonder if I can have a process to deduct the initial positions for the absolute coordinates for the initial positions in relative coordinates.

Thanks a lot for your ideas and help.

Hello,

In my model, in order to better follow a analytical study, i would like to make some calculations with my paramters.

For example, I have defined :

xa=1

ya=2

R=sqrt(xa²+ya²)

I would define R in the parameters area so as to use it for some definitions in the definition of body (i use especially maplesim for multibody systems.)

How is it possible to define parameters thanks to relations ?

Hello all,

When I try to do this example, in the multibody analysis, http://www.maplesoft.com/products/maplesim/ModelGallery/detail.aspx?id=137

Thats already written :

 

but when I enter theses formulas(mModel & MB), that write instead of the example:

"Analyzing system..."
"Performing constraint analysis..."
"The system has 2 degree(s) of freedom. It is modeled using 2

generalized coordinate(s) coupled by 0 algebraic constraint(s\

And I have no result if i do vPosCons := MB:-GetPosCons(); . What am I doing wrong?

Thank you

Hello,

I would like to open a modelica model with MapleSIM. When I do "import modelica", I received the error message : "import failed : no library found".

I believed the modelica library was already installed on maplesim but may be not. Do I need to install modelica library ? and if yes, how ?

More generally speaking, how can I do to open a modelica model on maplesim?

Thank you for your help.

I have some data for a model in MapleSim that I would like to use a time look up table with.  I've found that the two options for interpolation are linear and 1st derivative, but the data was intended to be interpretted as piecewise constant.  Is there any way to acheive this option in MapleSim?

Hi

I tried to import the modelica library Buildings1.6 from the modelica website and get always the error "Nothing found in the modelica library". 

Is it possible to import modelica libraries? 

Thank you very much

Does MapleSim 6 cover temperature dependent fluid media? In the modelica standard library (MSL), there is for example a medium model for T-dependent properties, defined by tables or polynomials (Modelica.Media.Incompressible).

 

Is it included in MapleSim 6 or can be somehow modelled?

 

Thanks!

Maplesoft regularly hosts live webinars on a variety of topics. Below you will find details on some upcoming webinars we think may be of interest to the MaplePrimes community.  For the complete list of upcoming webinars, visit our website.

 

Hollywood Math (with more new examples!)

Over its storied and intriguing history, Hollywood has entertained us with many mathematical moments in film. John Nash in “A Beautiful Mind,” the brilliant janitor in “Good Will Hunting,” the number theory genius in “Pi,” and even Abbott and Costello are just a few of the Hollywood “mathematicians” that come to mind.

Although the widespread presentation of mathematics on the silver screen is not always entirely accurate, it does serve as a great introduction to the study of mathematics in general. During this webinar Maplesoft will present a number of examples of mathematics in film. See relevant, exciting examples that you can use to engage your students.At the end of the webinar you’ll be given an opportunity to download an application containing all of the Hollywood examples that we demonstrate.

To join us for the live presentation, please click here to register.

 

Applications of Symbolic Computation in Control Design

You may already use Maple and/or MapleSim within your organization to solve various problems, but did you know that they have capabilities for control design as well? In one of our upcoming featured webinars for this month, we will explore the Control Design toolbox including the ability to extract symbolic equations of plant models, perform symbolic linearization, design symbolic controllers, and generate very fast code for HIL testing.

The following examples will be demonstrated:

• PID Control

• LQR, Kalman filter design

• Gain scheduling

• Feedback linearization

To join us for the live presentation, please click here to register.

Updates are now available for both Maple 18 and MapleSim 6.4.

Maple 18.01 includes a variety of enhancements, including:

  • Significantly enhanced  efficiency for many  numerical linear algebra computations
  • New keyboard shortcuts for “Execute All” ([Ctrl or Cmd]+[Shift]+[Enter]) and for entering slideshow mode ([F11] or [Cmd]+[F11])
  • Improved export of 2-D plots
  • PDF export improvements for documents that include  code edit regions
  • Enhancements to the limit command

 To get this update, you can use Tools>Check for Updates from within Maple, or visit Maple 18.01 Downloads.

MapleSim 6.4.01 includes:

  • Improvements to the templates for creating custom components using discrete state space and discrete transfer function descriptions
  • Improved handling of variable names that include both symbols and numbers
  • UTF-8 filename support
  • Improved backwards compatibility of the Parameter Inspector with older models

 

In MapleSim, use  Help>Check for Updates or visit MapleSim 6.4.01 Update. For best performance, we recommend that you run MapleSim 6.4.01 with Maple 18.01.

 

eithne

Hi everybody.

 

There are several weeks I'm on a school project and for it we need a Maplesim Simulation. It contains a sine voltage (source), a diode bridge (simplify), a condenser and a resistor. The problem is : when I want to simulate it, an error message appears : System is undetermined. I dopn't understand why I've this and from where's the problem...

 

If you could help me asap, it will be very very nice.

 

Have a nice day.

Recently I started to learn to use maplesim. I wanted to set up a feedback system which is used to control the speed of DC motor. I don't know how to build it. Please give me some advice. I really appreciate your help.

Hi

I want to create a linearied model for a single or multi degree of freedom vibration system by MapleSim. i faced a lot of problem such as causalize ports, i search the user manual but i didn't find it useful. i attach a very simply one degree of freedom vibration system. i wondering if every one create a linearized model for it. my final goal is governing the equation and determine the natural frequency with nyquist plots. i have mapleSim 6.2 and Maple 17. Thanks

 

prob1.msim

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