MATLAB: (simulink beginner) : cannot load a time series from workspace

Question

Hi all,

I am trying to figure out how to make some simple things work in Simulink. For example I have a matlab function which computes the position of an object given it's previous position and its velocity, as follows:

function [xnew vnew] = miModel(x,v,dt)
    % x is the current position 
    % v is the current velocity
      xnew  = x + dt*velocity;   % xnew is the new position
      vnew  = v;                 % new velocity =v in this example
  end

I want to load the 'velocity' variable from workspace, using the 'FromWorkspace' block. I define the velocity variable in the required structure as follows:

velocity.time = [linspace(0,1,100)]'; % 100
velocity.signals.values = [0*ones(50,1); 1*ones(50,1)] ;
velocity.signals.dimensions = [1];

I construct my model as shown below..

or here for a fullsize image:

http://www.freeimagehosting.net/newuploads/zpov6.png

when I run the simulation, it does not read the values I provide;i.e., first 50 iterations with velocity 0, and the other 50 with velocity =1; Please note that I am using a simple model in 1-D (velocity and position on x-axis only). Also, since I am working in discrete time, I set my solver to 'discrete' with fixed step = 1;

Any ideas? Many thanks…from a simulink beginner M

Answer 1

how to set a variable from workspace

time=0:0.1:10
signal=sin(t)
variable=[time;signal]'