Modelica.Blocks.Sources

Library of signal source blocks generating Real and Boolean signals

Information

This package contains source components, i.e., blocks which have only output signals. These blocks are used as signal generators for Real, Integer and Boolean signals.

All Real source signals (with the exception of the Constant source) have at least the following two parameters:

The offset parameter is especially useful in order to shift the corresponding source, such that at initial time the system is stationary. To determine the corresponding value of offset, usually requires a trimming calculation.

Extends from Modelica.Icons.SourcesPackage (Icon for packages containing sources).

Package Content

Name	Description
RealExpression	Set output signal to a time varying Real expression
IntegerExpression	Set output signal to a time varying Integer expression
BooleanExpression	Set output signal to a time varying Boolean expression
Clock	Generate actual time signal
Constant	Generate constant signal of type Real
Step	Generate step signal of type Real
Ramp	Generate ramp signal
Sine	Generate sine signal
Cosine	Generate cosine signal
ExpSine	Generate exponentially damped sine signal
Exponentials	Generate a rising and falling exponential signal
Pulse	Generate pulse signal of type Real
SawTooth	Generate saw tooth signal
Trapezoid	Generate trapezoidal signal of type Real
KinematicPTP	Move as fast as possible along a distance within given kinematic constraints
KinematicPTP2	Move as fast as possible from start to end position within given kinematic constraints with output signals q, qd=der(q), qdd=der(qd)
TimeTable	Generate a (possibly discontinuous) signal by linear interpolation in a table
CombiTimeTable	Table look-up with respect to time and linear/periodic extrapolation methods (data from matrix/file)
BooleanConstant	Generate constant signal of type Boolean
BooleanStep	Generate step signal of type Boolean
BooleanPulse	Generate pulse signal of type Boolean
SampleTrigger	Generate sample trigger signal
BooleanTable	Generate a Boolean output signal based on a vector of time instants
RadioButtonSource	Boolean signal source that mimics a radio button
IntegerConstant	Generate constant signal of type Integer
IntegerStep	Generate step signal of type Integer
IntegerTable	Generate an Integer output signal based on a table matrix with [time, yi] values

Modelica.Blocks.Sources.RealExpression

Set output signal to a time varying Real expression

Information

The (time varying) Real output signal of this block can be defined in its parameter menu via variable y. The purpose is to support the easy definition of Real expressions in a block diagram. For example, in the y-menu the definition "if time < 1 then 0 else 1" can be given in order to define that the output signal is one, if time ≥ 1 and otherwise it is zero. Note, that "time" is a built-in variable that is always accessible and represents the "model time" and that Variable y is both a variable and a connector.

Parameters

Connectors

Modelica.Blocks.Sources.IntegerExpression

Set output signal to a time varying Integer expression

Information

The (time varying) Integer output signal of this block can be defined in its parameter menu via variable y. The purpose is to support the easy definition of Integer expressions in a block diagram. For example, in the y-menu the definition "if time < 1 then 0 else 1" can be given in order to define that the output signal is one, if time ≥ 1 and otherwise it is zero. Note, that "time" is a built-in variable that is always accessible and represents the "model time" and that Variable y is both a variable and a connector.

Parameters

Connectors

Modelica.Blocks.Sources.BooleanExpression

Set output signal to a time varying Boolean expression

Information

The (time varying) Boolean output signal of this block can be defined in its parameter menu via variable y. The purpose is to support the easy definition of Boolean expressions in a block diagram. For example, in the y-menu the definition "time >= 1 and time <= 2" can be given in order to define that the output signal is true in the time interval 1 ≤ time ≤ 2 and otherwise it is false. Note, that "time" is a built-in variable that is always accessible and represents the "model time" and that Variable y is both a variable and a connector.

Parameters

Connectors

Modelica.Blocks.Sources.Clock

Generate actual time signal

Information

The Real output y is a clock signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Constant

Generate constant signal of type Real

Information

The Real output y is a constant signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Step

Generate step signal of type Real

Information

The Real output y is a step signal:

Extends from Interfaces.SignalSource (Base class for continuous signal source).

Parameters

Connectors

Modelica.Blocks.Sources.Ramp

Generate ramp signal

Information

The Real output y is a ramp signal:

If parameter duration is set to 0.0, the limiting case of a Step signal is achieved.

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Sine

Generate sine signal

Information

The Real output y is a sine signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Cosine

Generate cosine signal

Information

The Real output y is a cosine signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.ExpSine

Generate exponentially damped sine signal

Information

The Real output y is a sine signal with exponentially changing amplitude:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Exponentials

Generate a rising and falling exponential signal

Information

The Real output y is a rising exponential followed by a falling exponential signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Pulse

Generate pulse signal of type Real

Information

The Real output y is a pulse signal:

Extends from Modelica.Blocks.Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.SawTooth

Generate saw tooth signal

Information

The Real output y is a saw tooth signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.Trapezoid

Generate trapezoidal signal of type Real

Information

The Real output y is a trapezoid signal:

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.KinematicPTP

Move as fast as possible along a distance within given kinematic constraints

Information

The goal is to move as fast as possible along a distance deltaq under given kinematical constraints. The distance can be a positional or angular range. In robotics such a movement is called PTP (Point-To-Point). This source block generates the acceleration qdd of this signal as output:

After integrating the output two times, the position q is obtained. The signal is constructed in such a way that it is not possible to move faster, given the maximally allowed velocity qd_max and the maximally allowed acceleration qdd_max.

If several distances are given (vector deltaq has more than 1 element), an acceleration output vector is constructed such that all signals are in the same periods in the acceleration, constant velocity and deceleration phase. This means that only one of the signals is at its limits whereas the others are synchronized in such a way that the end point is reached at the same time instant.

This element is useful to generate a reference signal for a controller which controls a drive train or in combination with model Modelica.Mechanics.Rotational.Accelerate to drive a flange according to a given acceleration.

Extends from Interfaces.MO (Multiple Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.KinematicPTP2

Move as fast as possible from start to end position within given kinematic constraints with output signals q, qd=der(q), qdd=der(qd)

Information

The goal is to move as fast as possible from start position q_begin to end position q_end under given kinematical constraints. The positions can be translational or rotational definitions (i.e., q_begin/q_end is given). In robotics such a movement is called PTP (Point-To-Point). This source block generates the position q(t), the speed qd(t) = der(q), and the acceleration qdd = der(qd) as output. The signals are constructed in such a way that it is not possible to move faster, given the maximally allowed velocity qd_max and the maximally allowed acceleration qdd_max:

If vectors q_begin/q_end have more than 1 element, the output vectors are constructed such that all signals are in the same periods in the acceleration, constant velocity and deceleration phase. This means that only one of the signals is at its limits whereas the others are synchronized in such a way that the end point is reached at the same time instant.

This element is useful to generate a reference signal for a controller which controls, e.g., a drive train, or to drive a flange according to a given acceleration.

Extends from Modelica.Blocks.Icons.Block (Basic graphical layout of input/output block).

Parameters

Connectors

Modelica.Blocks.Sources.TimeTable

Generate a (possibly discontinuous) signal by linear interpolation in a table

Information

This block generates an output signal by linear interpolation in a table. The time points and function values are stored in a matrix table[i,j], where the first column table[:,1] contains the time points and the second column contains the data to be interpolated. The table interpolation has the following properties:

• The time points need to be monotonically increasing.
• Discontinuities are allowed, by providing the same time point twice in the table.
• Values outside of the table range, are computed by extrapolation through the last or first two points of the table.
• If the table has only one row, no interpolation is performed and the function value is just returned independently of the actual time instant.
• Via parameters startTime and offset the curve defined by the table can be shifted both in time and in the ordinate value.
• The first point in time always has to be set to 0, e.g., table=[1,1;2,2] is illegal. If you want to shift the time table in time use the startTime parameter instead.
• The table is implemented in a numerically sound way by generating time events at interval boundaries. This generates continuously differentiable values for the integrator.
• Via parameter timeScale the first column of the table array can be scaled, e.g. if the table array is given in hours (instead of seconds) timeScale shall be set to 3600.

Example:

   table = [0  0
            1  0
            1  1
            2  4
            3  9
            4 16]
If, e.g., time = 1.0, the output y =  0.0 (before event), 1.0 (after event)
    e.g., time = 1.5, the output y =  2.5,
    e.g., time = 2.0, the output y =  4.0,
    e.g., time = 5.0, the output y = 23.0 (i.e., extrapolation).

Extends from Interfaces.SO (Single Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.CombiTimeTable

Table look-up with respect to time and linear/periodic extrapolation methods (data from matrix/file)

Information

This block generates an output signal y[:] by linear interpolation in a table. The time points and function values are stored in a matrix table[i,j], where the first column table[:,1] contains the time points and the other columns contain the data to be interpolated.

Via parameter columns it can be defined which columns of the table are interpolated. If, e.g., columns={2,4}, it is assumed that 2 output signals are present and that the first output is computed by interpolation of column 2 and the second output is computed by interpolation of column 4 of the table matrix. The table interpolation has the following properties:

• The time points need to be strictly increasing if smoothness is ContinuousDerivative, otherwise monotonically increasing.
• Discontinuities are allowed, by providing the same time point twice in the table.
• Values outside of the table range, are computed by extrapolation according to the setting of parameter extrapolation:

    extrapolation = 1: hold the first or last value of the table,
                       if outside of the table scope.
                  = 2: extrapolate by using the derivative at the first/last table
                       points if outside of the table scope.
                       (If smoothness is LinearSegments or ConstantSegments
                       this means to extrapolate linearly through the first/last
                       two table points.).
                  = 3: periodically repeat the table data
                       (periodical function).
                  = 4: no extrapolation, i.e. extrapolation triggers an error
  

• Via parameter smoothness it is defined how the data is interpolated:

    smoothness = 1: linear interpolation
               = 2: Akima interpolation: Smooth interpolation by cubic Hermite
                    splines such that der(y) is continuous, also if extrapolated.
               = 3: constant segments
               = 4: Fritsch-Butland interpolation: Smooth interpolation by cubic
                    Hermite splines such that y preserves the monotonicity and
                    der(y) is continuous, also if extrapolated.
               = 5: Steffen interpolation: Smooth interpolation by cubic Hermite
                    splines such that y preserves the monotonicity and der(y)
                    is continuous, also if extrapolated.
  

• If the table has only one row, no interpolation is performed and the table values of this row are just returned.
• Via parameters startTime and offset the curve defined by the table can be shifted both in time and in the ordinate value. The time instants stored in the table are therefore relative to startTime. If time < startTime, no interpolation is performed and the offset is used as ordinate value for all outputs.
• The table is implemented in a numerically sound way by generating time events at interval boundaries. An interval boundary is defined by two identical time values following each other. For example

     table = [0, 0;
              1, 0;
              1, 1;
              2, 3;
              3, 5;
              3, 2;
              4, 4;
              5, 5];
  

  defines three intervalls: 0..1, 1..3, 3..5. Within an interval the defined interpolation method is applied (so the table outputs within an interval are continuous,and if the interpolation method is smooth, also continuously differentiable). No time events are generated within an interval in order that also intervals with many points do not reduce the simulation efficiency (note in package Modelica version 3.2 and earlier, time events had been generated).
  If the table points are largely changing, it is adviseable to force time events by duplicating every time point (especially, if the model in which the table is present allows the variable step integrator to make large integrator steps). For example, if a sawtooth signal is defined with the table, it is more reliable to define the table as:

     table = [0, 0;
              1, 2;
              1, 2;
              2, 0;
              2, 0;
              3, 2;
              3, 2];
  

  instead of

     table = [0, 0;
              1, 2;
              2, 0;
              3, 2];
  

  because time events are then generated at every time point.
• Via parameter timeScale the first column of the table array can be scaled, e.g. if the table array is given in hours (instead of seconds) timeScale shall be set to 3600.
• For special applications it is sometimes needed to know the minimum and maximum time instant defined in the table as a parameter. For this reason parameters t_min/t_minScaled and t_max/t_maxScaled are provided and can be accessed from the outside of the table object. Whereas t_min and t_max define the scaled abscissa values (using parameter timeScale) in SIunits.Time, t_minScaled and t_maxScaled define the unitless original abscissa values of the table.

Example:

   table = [0, 0;
            1, 0;
            1, 1;
            2, 4;
            3, 9;
            4, 16]; extrapolation = 3 (default)
If, e.g., time = 1.0, the output y =  0.0 (before event), 1.0 (after event)
    e.g., time = 1.5, the output y =  2.5,
    e.g., time = 2.0, the output y =  4.0,
    e.g., time = 5.0, the output y = 23.0 (i.e., extrapolation via last 2 points).

The table matrix can be defined in the following ways:

1. Explicitly supplied as parameter matrix "table", and the other parameters have the following values:

      tableName is "NoName" or has only blanks,
      fileName  is "NoName" or has only blanks.
   

2. Read from a file "fileName" where the matrix is stored as "tableName". Both ASCII and MAT-file format is possible. (The ASCII format is described below). The MAT-file format comes in four different versions: v4, v6, v7 and v7.3. The library supports at least v4, v6 and v7 whereas v7.3 is optional. It is most convenient to generate the MAT-file from FreeMat or MATLAB® by command

      save tables.mat tab1 tab2 tab3
   

   or Scilab by command

      savematfile tables.mat tab1 tab2 tab3
   

   when the three tables tab1, tab2, tab3 should be used from the model.
   Note, a fileName can be defined as URI by using the helper function loadResource.
3. Statically stored in function "usertab" in file "usertab.c". The matrix is identified by "tableName". Parameter fileName = "NoName" or has only blanks. Row-wise storage is always to be preferred as otherwise the table is reallocated and transposed.

When the constant "NO_FILE_SYSTEM" is defined, all file I/O related parts of the source code are removed by the C-preprocessor, such that no access to files takes place.

If tables are read from an ASCII-file, the file needs to have the following structure ("-----" is not part of the file content):

-----------------------------------------------------
#1
double tab1(6,2)   # comment line
  0   0
  1   0
  1   1
  2   4
  3   9
  4  16
double tab2(6,2)   # another comment line
  0   0
  2   0
  2   2
  4   8
  6  18
  8  32
-----------------------------------------------------

Note, that the first two characters in the file need to be "#1" (a line comment defining the version number of the file format). Afterwards, the corresponding matrix has to be declared with type (= "double" or "float"), name and actual dimensions. Finally, in successive rows of the file, the elements of the matrix have to be given. The elements have to be provided as a sequence of numbers in row-wise order (therefore a matrix row can span several lines in the file and need not start at the beginning of a line). Numbers have to be given according to C syntax (such as 2.3, -2, +2.e4). Number separators are spaces, tab ( ), comma (,), or semicolon (;). Several matrices may be defined one after another. Line comments start with the hash symbol (#) and can appear everywhere. Other characters, like trailing non comments, are not allowed in the file.

MATLAB is a registered trademark of The MathWorks, Inc.

Extends from Modelica.Blocks.Interfaces.MO (Multiple Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.BooleanConstant

Generate constant signal of type Boolean

Information

The Boolean output y is a constant signal:

Extends from Interfaces.partialBooleanSource (Partial source block (has 1 output Boolean signal and an appropriate default icon)).

Parameters

Connectors

Modelica.Blocks.Sources.BooleanStep

Generate step signal of type Boolean

Information

The Boolean output y is a step signal:

Extends from Interfaces.partialBooleanSource (Partial source block (has 1 output Boolean signal and an appropriate default icon)).

Parameters

Connectors

Modelica.Blocks.Sources.BooleanPulse

Generate pulse signal of type Boolean

Information

The Boolean output y is a pulse signal:

Extends from Modelica.Blocks.Interfaces.partialBooleanSource (Partial source block (has 1 output Boolean signal and an appropriate default icon)).

Parameters

Connectors

Modelica.Blocks.Sources.SampleTrigger

Generate sample trigger signal

Information

The Boolean output y is a trigger signal where the output y is only true at sample times (defined by parameter period) and is otherwise false.

Extends from Interfaces.partialBooleanSource (Partial source block (has 1 output Boolean signal and an appropriate default icon)).

Parameters

Connectors

Modelica.Blocks.Sources.BooleanTable

Generate a Boolean output signal based on a vector of time instants

Information

The Boolean output y is a signal defined by parameter vector table. In the vector time points are stored. At every time point, the output y changes its value to the negated value of the previous one.

The precise semantics is:

  if size(table,1) == 0 then
     y = startValue;
  else
     //            time < table[1]: y = startValue
     // table[1] ≤ time < table[2]: y = not startValue
     // table[2] ≤ time < table[3]: y = startValue
     // table[3] ≤ time < table[4]: y = not startValue
     // ...
  end if;

Note, the result of this block depends only on time, but not on the simulation start time (changing the simulation start time, will result exactly in the same output y at the same time instant ti);

Extends from Interfaces.partialBooleanSource (Partial source block (has 1 output Boolean signal and an appropriate default icon)).

Parameters

Connectors

Modelica.Blocks.Sources.RadioButtonSource

Boolean signal source that mimics a radio button

Information

Boolean signal source that mimics a radio button: Via a table, a radio button is pressed (i.e., the output 'on' is set to true) and is reset when an element of the Boolean vector 'reset' becomes true. If both appear at the same time instant, setting the button according to the table has a higher priority as resetting the button. Example:

  RadioButtonSource start(buttonTimeTable={1,3}, reset={stop.on});
  RadioButtonSource stop (buttonTimeTable={2,4}, reset={start.on});

The "start" button is pressed at time=1 s and time=3 s, whereas the "stop" button is pressed at time=2 s and time=4 s. This gives the following result:

This example is also available in Modelica.Blocks.Examples.Interaction1

Parameters

Connectors

Modelica.Blocks.Sources.IntegerConstant

Generate constant signal of type Integer

Information

The Integer output y is a constant signal:

Extends from Interfaces.IntegerSO (Single Integer Output continuous control block).

Parameters

Connectors

Modelica.Blocks.Sources.IntegerStep

Generate step signal of type Integer

Information

The Integer output y is a step signal:

Extends from Interfaces.IntegerSignalSource (Base class for continuous Integer signal source).

Parameters

Connectors

Modelica.Blocks.Sources.IntegerTable

Generate an Integer output signal based on a table matrix with [time, yi] values

Information

This block generates an Integer output signal by using a table. The time points and y-values are stored in a matrix table[i,j], where the first column table[:,1] contains the Real time points and the second column contains the Integer value of the output y at this time point.

An assert is triggered, if no table values are provided, if the time points are not strict monotonically increasing, or if the second column of the table matrix does not contain Integer values.

If the simulation time is less than the first table time instant, then the output y = table[1,2].
If the simulation time is greater than the last table time instant, then the output y = table[end,2].

Example:

   table = [  0, 1;
              1, 4;
            1.5, 5;
              2, 6];

results in the following output:

Extends from Interfaces.IntegerSO (Single Integer Output continuous control block).

Parameters

Connectors