# NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/

## Information about this web site => Request for physics Simulations => Topic started by: pavwell on May 21, 2010, 12:37:43 pm

 Title: Magnetic levitation model Post by: pavwell on May 21, 2010, 12:37:43 pm Hello !Please, could anyone hepl me with creating Magnetic Levitation of small ball model in EJS ?Thanks a lot ! Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 21, 2010, 05:22:36 pm Please provide more information: design/dimension of the system/shape/...etc (whatever  you have in mind)And the physics to be modeled. Title: Re: Magnetic levitation model Post by: pavwell on May 21, 2010, 05:40:44 pm Hello Parameters and desing is in attachmement Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 21, 2010, 09:58:50 pm There is one thing I do not understand for the main equation in the above document$m_k \ddot{x}=\frac{i^2k}{(x-x_0)^2}-m_k g$What is the meaning of $i$ in the above equatoion? Title: Re: Magnetic levitation model Post by: pavwell on May 21, 2010, 10:05:43 pm Sorry !I forget for this. ,,i,, is constant. Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 22, 2010, 11:56:07 pm Why there are two constant? $i^2 k$, and what is the value of $i$?L0=0.019 does it mean 1.9cm? Title: Re: Magnetic levitation model Post by: pavwell on May 23, 2010, 01:33:28 am L0 is 1.9 cm...and ,,i, is : electrical power [A] and value is =0.33 Amper Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 23, 2010, 08:30:37 am Do you mean i is electric current? (instead of power)Is it a control variable? or it it a constant??? The system seems to be an un-stable equilibrium system. It need some feedback to make it stable, Right? Title: Re: Magnetic levitation model Post by: pavwell on May 23, 2010, 12:21:25 pm Yes, it is electric current throught induction. And feedback is needed. In attachment I send you basic scheme. Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 23, 2010, 02:43:22 pm I try to implement a virtual feedback to create the following stable case.However, you need to change parameters to fit with your own system.  Title: Re: Magnetic levitation model Post by: pavwell on May 23, 2010, 09:20:12 pm Thanks a lot for your job. But when I try to run in EJS 4.2, it gives me an compilation error. Please, what EJS version i need to use ?? Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 23, 2010, 11:35:36 pm The above simulation was generated with EJS4.2 Title: Re: Magnetic levitation model Post by: pavwell on May 23, 2010, 11:45:01 pm please, could you make this project at EJS 3.4.7 ?? Thanks a lot !!! Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 24, 2010, 08:23:39 am You should be able to copy the code to 3.47 if you open two version of EJS Just define  the same variables, copy the same initialization/evolution/... and add similar GUI elements.The only difference is that there is no two states button in EJS 3.47 So the play/pause button need to be separate as two buttons.And you need to adjust the code to fit with your system.I am willing to help you do you job: I already give you an example.And you should be able to finish it by yourself! You need to at least try it! Title: Re: Magnetic levitation model Post by: pavwell on May 25, 2010, 03:29:02 am When i try to run this XML file under Ejs 4.2 , system gives me an error ! Compilation error. When i look over the code i found one red line ay=calF(....). Dont you konw what could be a problem ?? Title: Re: Magnetic levitation model Post by: Fu-Kwun Hwang on May 25, 2010, 07:57:39 am I also use EJS 4.2 However, I did not find any error. So I do not know how to help.The ay was defined as double with initial value "calF(y,vy)/m-g"It can be re-assigned to 0. without affect the code.