User manual MATHWORKS SIMULINK CONTROL DESIGN 3

[. . . ] Simulink® Control DesignTM 3 User's Guide How to Contact MathWorks Web Newsgroup www. mathworks. com/contact_TS. html Technical Support www. mathworks. com comp. soft-sys. matlab suggest@mathworks. com bugs@mathworks. com doc@mathworks. com service@mathworks. com info@mathworks. com Product enhancement suggestions Bug reports Documentation error reports Order status, license renewals, passcodes Sales, pricing, and general information 508-647-7000 (Phone) 508-647-7001 (Fax) The MathWorks, Inc. 3 Apple Hill Drive Natick, MA 01760-2098 For contact information about worldwide offices, see the MathWorks Web site. Simulink® Control DesignTM User's Guide © COPYRIGHT 2004­2010 by The MathWorks, Inc. The software described in this document is furnished under a license agreement. The software may be used or copied only under the terms of the license agreement. [. . . ] io is a vector of objects and has an entry for each linearization port used by the block. Each object within the vector, io, has the following properties: Active Block OpenLoop Set this value to 'on', when the I/O is used for linearization, and 'off' otherwise Name of the block the with which I/O is associated Set this value to 'on', when the feedback loop at the I/O is open, and 'off', when it is closed 7-76 getlinio PortNumber Type Integer referring to the output port with which the I/O is associated Choose one of the following linearization I/O types: · 'in': linearization input point · 'out': linearization output point · 'outin': linearization output then input point · 'inout': linearization input then output point Description String description of the I/O object You can edit this I/O object to change its properties. Alternatively, you can change the properties of io using the set function. To upload an edited I/O object to the Simulink model diagram, use the setlinio function. Use I/O objects with the function linearize to create linear models. Example Find linearization inputs/outputs in a Simulink model. Before creating a vector of I/O objects using getlinio, you must add linearization annotations representing the I/Os, such as input points or output points, to a Simulink model. Open the Simulink model magball by typing magball at the MATLAB prompt. Right-click the signal line between the Magnetic Ball Plant and the Controller. Select Linearization Points > Input Point from the menu to place an input point on this signal line. A small arrow pointing toward a small circle just above the signal line represents the input point. Select Linearization Points > Output 7-77 getlinio Point from the menu to place an output point on this signal line. A small arrow pointing away from a small circle just above the signal line represents the output point. To create a vector of I/O objects for this model, type: io=getlinio('magball') This syntax returns a formatted display of the linearization I/Os. Linearization IOs: -------------------------Block magball/Controller, Port 1 is marked with the following properties: - No Loop Opening - An Input Perturbation - No signal name. Linearization will use the block name Block magball/Magnetic Ball Plant, Port 1 is marked with the following properties: - An Output Measurement - No Loop Opening - No signal name. Linearization will use the block name There are two entries in the vector, io, representing the two linearization annotations previously set in the model diagram. MATLAB displays: · the name of the block associated with the I/O · the port number associated with the I/O · the type of IO (input perturbation or output measurement referring to an input point or output point respectively) · whether the IO is also a loop opening By default, the I/Os have no loop openings. Display the properties of each I/O object in more detail using the get function. 7-78 getlinio Find linearization inputs/outputs in a Linear Analysis Plots block to update the I/Os: 1 Open the watertank model, and specify input and output (I/O). a Right-click the Desired Water Level output signal, and select Linearization Points > Input Point. b Right-click the Water-Tank System output signal, and select Linearization Points > Output Point. The linearization I/O markers appear in the model, as shown in the next figure. Alternatively, you can use linio. 2 Drag and drop a Bode Plot block from the Simulink Control Design Linear Analysis Plots library into the model window. 3 Find all I/Os used by the Bode Plot block. io = getlinio('watertank/Bode Plot') When you drag and drop the block, the block I/Os are set to the model I/Os. The following results appear at the MATLAB prompt: Linearization IOs: -------------------------- 7-79 getlinio Block watertank/Desired - No Loop Opening - An Input Perturbation Water Level, Port 1 is marked with the following properties: - No signal name. Linearization will use the block name Block watertank/Water-Tank System, Port 1 is marked with the following properties: - An Output Measurement - No Loop Opening - No signal name. Linearization will use the block name 4 Open the loop specified by the block I/Os. io(2). OpenLoop = 'on'; Note The loop opening does not affect the model I/Os. 5 Update the I/O in the Bode Plot block. oldio = setlinio('watertank/Bode Plot', io) See Also get, linearize, linio, set, setlinio 7-80 getlinplant Purpose Syntax Description Compute open-loop plant model from Simulink diagram [sysp, sysc] = getlinplant(block, op) [sysp, sysc] = getlinplant(block, op, options) [sysp, sysc] = getlinplant(block, op) Computes the open-loop plant seen by a Simulink block labeled block (where block specifies the full path to the block). [. . . ] · Simulating the model by clicking or selecting Simulation > Start. This action also linearizes the portion of the model between the specified linearization input and output. · Adding legend on the linear system characteristic plot by clicking . See Also Tutorials Check Singular Value Characteristics · "Visualize Bode Plot of Simulink Model During Simulation" on page 2-28 9-305 Singular Value Plot · "Visualize Linear System Characteristics at Multiple Simulation Snapshots" on page 2-52 · "Visualize Linear System Characteristics of a Continuous-Time Model Discretized During Simulation" on page 2-60 · Plotting Linear System Characteristics of a Chemical Reactor 9-306 Trigger-Based Operating Point Snapshot Purpose Library Description Generate operating points, linearizations, or both at triggered events Simulink Control Design Attach this block to a signal in a model when you want to take a snapshot of the system's operating point at triggered events such as when the signal crosses zero or when the signal sends a function call. To extract the operating point or perform the linearization, you need to simulate the model using either the findop or linearize functions or the simulation snapshots option in the Control and Estimation Tools Manager. [. . . ]