Comments on: Modeling Mechanical Systems: The Double Pendulum http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/ This blog is about Simulink. Sun, 22 Nov 2009 23:39:27 +0000 http://wordpress.org/?v=2.3.1 By: adrian chavarro http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-892 adrian chavarro Wed, 11 Nov 2009 12:53:20 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-892 Great tool, for educational and sicentific, simulation. I would like to know where can i place a motor for controlling position on inverterted pendulum....thanks... Great tool, for educational and sicentific, simulation.

I would like to know where can i place a motor for controlling position on inverterted pendulum….thanks…

]]> By: Guy http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-768 Guy Wed, 03 Jun 2009 13:17:39 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-768 @tesfaye - The SimMechanics documentation explains how to compute the equilibrium configuration of a model. This section is titled "Trimming Mechanical Model" and can be found online at: http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/mech/ug/f0-6194.html This section uses a double pendulum example where the two sections of the pendulum are linked by a rotational spring. @tesfaye - The SimMechanics documentation explains how to compute the equilibrium configuration of a model. This section is titled “Trimming Mechanical Model” and can be found online at:

http://www.mathworks.com/access/helpdesk/help/toolbox/physmod/mech/ug/f0-6194.html

This section uses a double pendulum example where the two sections of the pendulum are linked by a rotational spring.

]]> By: tesfaye kebede http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-765 tesfaye kebede Thu, 28 May 2009 14:30:11 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-765 Dr.that is a nice model,but u have to show the equilibrium configuration too. Dr.that is a nice model,but u have to show the equilibrium configuration too.

]]> By: Guy Rouleau http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-735 Guy Rouleau Wed, 22 Apr 2009 12:24:31 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-735 Hi Hendry, It is possible to implement a mobile robot using SimMechanics. To begin, you have to assemble the main parts of the robot, like wheels, suspension and main body. After it is done, the most complex part is to define the interaction of the rover with the ground. One simple solution is to represent the ground as a stiff spring-damper system. Many contact dynamics models have been developed in the past and can be implemented in Simulink, for example the “magic formula” for tires. I can also mention that The MathWorks website provide a list of third party products and some of them are specialized in wheel contact dynamics: http://www.mathworks.com/products/connections/ To give an example of what a rover model can look like, I just submitted a file on the MATLAB Central. Please look for my profile to find it. I hope it helps Guy Rouleau Hi Hendry,

It is possible to implement a mobile robot using SimMechanics. To begin, you have to assemble the main parts of the robot, like wheels, suspension and main body. After it is done, the most complex part is to define the interaction of the rover with the ground. One simple solution is to represent the ground as a stiff spring-damper system. Many contact dynamics models have been developed in the past and can be implemented in Simulink, for example the “magic formula” for tires. I can also mention that The MathWorks website provide a list of third party products and some of them are specialized in wheel contact dynamics:

http://www.mathworks.com/products/connections/

To give an example of what a rover model can look like, I just submitted a file on the MATLAB Central. Please look for my profile to find it.

I hope it helps

Guy Rouleau

]]> By: X http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-734 X Wed, 22 Apr 2009 09:33:16 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-734 I would say "blasphemy" is to use a man's good name and reputation to rant in such an insulse manner. News seem to travel slowly in some parts of the world, sadly, Edward Norton Lorenz passed away on April 16th, 2008. Aleksandr Mikhailovich Lyapunov passed away on November 3rd 1918. It's everybody's guess what they would have thought of SimMechanics. X I would say “blasphemy” is to use a man’s good name and reputation to rant in such an insulse manner.

News seem to travel slowly in some parts of the world, sadly,

Edward Norton Lorenz passed away on April 16th, 2008.
Aleksandr Mikhailovich Lyapunov passed away on November 3rd 1918.

It’s everybody’s guess what they would have thought of SimMechanics.

X

]]> By: hendry http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-733 hendry Tue, 21 Apr 2009 18:55:57 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-733 realy nice, but now i have build a mobile robot motion models, can you help me?? realy nice, but now i have build a mobile robot motion models, can you help me??

]]> By: Seth http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-729 Seth Mon, 20 Apr 2009 01:47:09 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-729 @Alejandro - There are a few tools you should look at: <a href="http://www.mathworks.com/products/simscape/" rel="nofollow">SimScape</a>, <a href="http://www.mathworks.com/products/simelectronics/" rel="nofollow">SimElectronics</a> and <a href="http://www.mathworks.com/products/simpower/" rel="nofollow">SimPowerSystems</a>. Your choice of which tool to use will depending on what you are trying to model. Good luck! @Alejandro - There are a few tools you should look at: SimScape, SimElectronics and SimPowerSystems. Your choice of which tool to use will depending on what you are trying to model. Good luck!

]]> By: Alejandro P. Gómez R. http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-728 Alejandro P. Gómez R. Mon, 20 Apr 2009 00:52:57 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-728 It is a wonderful tool Mr. Seth Popinchalk. I would like to know if I can do the same for Electronic and Electric systems? Sincerely Alejandro It is a wonderful tool Mr. Seth Popinchalk. I would like to know if I can do the same for Electronic and Electric systems?

Sincerely

Alejandro

]]> By: Edward Norton Lorenz http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-705 Edward Norton Lorenz Tue, 10 Mar 2009 03:21:02 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-705 My, my...it seems that our friend Dr. Lyapunov is a bit agitated with the marvellous SimMechanics. Perhaps I can offer a few words in your favour, Mr Guy, to alleviate my colleagues acerbic, vituperative vitriolic remarks. The value of your tool seems to lie in exactly the characteristic in question. Namely, that it does not need dynamic analysis of the system being modelled. Perhaps if this tool was available to us in my youth, I would not have been sidetracked by a pesky initial condition in my Lorenz Equation describing the weather for 50 years. My detailed 12th order model of the weather system failed to produce the results expected-all that modelling for nothing-proving that building mathematical models may not be worth it sometimes. If I had not been trying to discover the chaotic behavior arising from my equations 50 years ago, perhaps today we could have solved global warming....and that, my friend, would have become known as the REAL butterfly effect! Former Professor at MIT Dr. Ed Lorenz My, my…it seems that our friend Dr. Lyapunov is a bit agitated with the marvellous SimMechanics.

Perhaps I can offer a few words in your favour, Mr Guy, to alleviate my colleagues acerbic, vituperative vitriolic remarks.

The value of your tool seems to lie in exactly the characteristic in question. Namely, that it does not need dynamic analysis of the system being modelled. Perhaps if this tool was available to us in my youth, I would not have been sidetracked by a pesky initial condition in my Lorenz Equation describing the weather for 50 years.

My detailed 12th order model of the weather system failed to produce the results expected-all that modelling for nothing-proving that building mathematical models may not be worth it sometimes.

If I had not been trying to discover the chaotic behavior arising from my equations 50 years ago, perhaps today we could have solved global warming….and that, my friend, would have become known as the REAL butterfly effect!

Former Professor at MIT
Dr. Ed Lorenz

]]> By: Aleksandr Mikhailovich Lyapunov http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-704 Aleksandr Mikhailovich Lyapunov Mon, 09 Mar 2009 05:21:35 +0000 http://blogs.mathworks.com/seth/2009/02/26/modeling-mechanical-systems-the-double-pendulum/#comment-704 Dear Mr. Seth Popinchalk. I could not rest in peace any longer. This blog post trivializes my life's work! My second method allows us to determine stability of system without solving model's ODE! SimMechanics gives no insight into stability! Why you use it!? What if, for some obscure initial condition not likely to be simulated, your system is unstable? how will you know? You make mistake to simulate system and not check stability? You must check stability! Checking stability means knowing dynamics! Mr Seth and Mr Guy, your attempt to destroy my work has failed! Read my book: The general problem of the stability of motion. I agree with mr. Amayreh's comments. I add this to it: it is important to model system with pencil, paper and simulate using abacus only! No shortcut. This is good education time, not LEGOS play time! SimMechanics is Blasphemy! Good bye. Aleksandr Mikhailovich Lyapunov Dear Mr. Seth Popinchalk.

I could not rest in peace any longer. This blog post trivializes my life’s work! My second method allows us to determine stability of system without solving model’s ODE! SimMechanics gives no insight into stability! Why you use it!? What if, for some obscure initial condition not likely to be simulated, your system is unstable? how will you know? You make mistake to simulate system and not check stability? You must check stability! Checking stability means knowing dynamics! Mr Seth and Mr Guy, your attempt to destroy my work has failed! Read my book: The general problem of the stability of motion.

I agree with mr. Amayreh’s comments. I add this to it: it is important to model system with pencil, paper and simulate using abacus only! No shortcut.

This is good education time, not LEGOS play time!

SimMechanics is Blasphemy!

Good bye.
Aleksandr Mikhailovich Lyapunov

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