Re: The 'Solving a Block Diagram in Mathematica' web page
- To: mathgroup at smc.vnet.net
- Subject: [mg23590] Re: The 'Solving a Block Diagram in Mathematica' web page
- From: Eckhard Hennig <hennig at itwm.uni-kl.de>
- Date: Sun, 21 May 2000 18:12:56 -0400 (EDT)
- Organization: ITWM
- References: <8g7272$j49@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Peltio schrieb in Nachricht <8g7272$j49 at smc.vnet.net>... >Just for the sake of knowing... >Is the block diagram given at: > >http://library.wolfram.com/howtos/block/ >(Solving a Block Diagram in Mathematica) > >correct? I'm not an expert of control systems, but, shouldn't the two >lower blocks be: > >(4s+2)/(s^2+2s+1) instead of 4s+2/(s^2+2s+1) >(s^2+2)/(s^2+14) instead of s^2+2/(s^2+14) Hi Peltio, indeed, the diagram and the calculations do not match. But even with the above corrections, the result appears to be incorrect. I computed the transfer function of the block diagram with Analog Insydes, and the result is slightly different: http://www.itwm.uni-kl.de/as/products/ai/BlockDiagram.nb (You can run these calculations with the evaluation version of Analog Insydes.) >Also, is there a particular convention that allows to understand which >node is adding and which one is subtracting? >Or am I missing something? Unless an input to a summing junction is explicitly marked with a minus sign, one can assume that the input is adding. But obviously, some minus signs have been forgotten in the diagram. Best regards, Eckhard ----------------------------------------------------------- Dr.-Ing. Eckhard Hennig mailto:hennig at itwm.uni-kl.de Institut fuer Techno- und Wirtschaftsmathematik e.V. (ITWM) Erwin-Schroedinger-Strasse, 67663 Kaiserslautern, Germany Voice: +49-(0)631-205-3126 Fax: +49-(0)631-205-4139 http://www.itwm.uni-kl.de/as/employees/hennig.html ITWM - Makers of Analog Insydes for Mathematica http://www.itwm.uni-kl.de/as/products/ai -----------------------------------------------------------