DUBSI - the Dutchroll Blockset for Simulink

Block-library: DUBSI

The Dutchroll Blockset for Simulink (in short: DUBSI) is a collection of several general-purpose Simulink blocks. The blockset is also available as the blocklibrary BLOCKLIB_MISC of the Flight Dynamics and Control Toolbox; DUBSI is the stand-alone version of that blocklibrary.

Why Dutchroll?

The 'Dutch Roll' is one of the characteristic motions of an airplane. It is a combination of rolling and yawing, which results in an elliptic motion of the wingtips. Because of this close relation with aircraft dynamics, the website for the Flight Dynamics and Control (FDC) Toolbox was named 'www.dutchroll.com' and all software projects and publications which have any relation with the FDC toolbox will be published under the 'Dutchroll Software' label.

The DUBSI blockset

The picture below gives an overview of the blockset. Click on the figure to see a full-size screenshot; then click on any individual block in that screenshot for help about that particular block.

DUBSI blocklibrary

Summary of the blocks

The blockset has been subdivided in 7 sections: Sinks, Gains, Signals & Switches, Discrete, Nonlinear, and Transformations. These sections largely mirror the usual Simulink libraries, except for the Transformations section, which contains three rotation matrices that can be used to express a vector in a different, rotated, reference frame. The 7 sections contain the following blocks:

Sources
     Block Fcn
generates a block-shaped signal
     Doublet
generates a 'doublet signal'; i.e. an upward block-signal, followed by a downward block-signal, or vice-versa
     Band-limited Ramp
generates a ramp signal with a fixed upper- or lower-limit
     n-Pulse Generator
generates a sequence of n evenly-spaced pulses
     1-cos wave
generates a wave signal, which is defined by an 1-cos function
     Source Selector
allows the user to select a source signal from a pull-down menu
Sinks
     To Workspace
alternative for the normal To Workspace block, which makes it possible to send outputs to a structure in the Matlab workspace
     To Workspace with throughput
same as above, except that this version can be placed in-line, thanks to its output port which passes through the input signal without changing it
Gains
     Scheduled Gain
multiplies the second input signal by a gain that depends on the first input signal
     Scheduled Gain (right to left)
same as above, but oriented from right to left
Signals & Switches
     On/Off Switch
switches a signal on or off, depending on the value of a switch control-signal
     Conditional Switch
selects either the first, or the third input value, depending on a switch criterion that is a function of the second input
     Output Director
directs an input signal to either the first or the second output port, depending on a threshold value
     Circuit Selector
activates one out of two signal circuits, depending on a threshold value
Discrete
     Moving Average
computes the moving average value from a user-specified number of evenly-spaced input samples
Nonlinear
     Soft Limiter
shapes the input signal according to a function that is similar to the shaping function of a Saturation block from the Simulink library 'Nonlinear', except that in this case the shaping function generates a 'soft' transition to the upper and lower limit values
     Norm
determines the norm (i.e. the length) of an input vector of arbitrary length
     Normalizer
normalizes vectors of arbitrary length
Transformations
     rot x
transforms a three-dimensional vector from one reference frame to another, whereby the new reference frame is obtained by rotating the old reference frame along its x-axis
     rot y
transforms a three-dimensional vector from one reference frame to another, whereby the new reference frame is obtained by rotating the old reference frame along its y-axis
     rot z
transforms a three-dimensional vector from one reference frame to another, whereby the new reference frame is obtained by rotating the old reference frame along its z-axis
     cross-product
determines the cross-product of two (3x1)-vectors

Copyright information

Dutchroll Blockset for Simulink, DUBSI, copyright 2002-2003, M.O. Rauw. DUBSI 1.0.2 is OSI Certified Open Source Software. It has been released under and is subject to the terms of the Open Software License (OSL), version 1.1. Please read this License carefully before using this software. If you do not or cannot agree to the terms of this License, please do not use this material.

A full list of contents of the DUBSI distribution can be found in the file README.TXT in the main DUBSI directory. Notice that the OSL 1.1 applies to all files mentioned in that document, plus all on-line helpfiles (*.html, *.gif, and *.css).

Availability

The DUBSI blockset is being distributed at no charge via SourceForge (a direct download link can be found here). Alternatively, a copy of the package can be obtained via the Matlab Central website.

May 4, 2003