VERSION 5.00
Begin VB.Form Form1 
   BackColor       =   &H00C0FFFF&
   Caption         =   "Form1"
   ClientHeight    =   7710
   ClientLeft      =   60
   ClientTop       =   390
   ClientWidth     =   11130
   LinkTopic       =   "Form1"
   ScaleHeight     =   7710
   ScaleWidth      =   11130
   StartUpPosition =   3  'Windows Default
End
Attribute VB_Name = "Form1"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Public inkey$

Private Sub Form_KeyPress(KeyAscii As Integer)
inkey$ = Chr(KeyAscii)
End Sub

Private Sub Form_Load()
'Screen 12
Show
Cls

f = 2   'feedback
d = 2   'damping


Form1.Scale (-40, 10)-(40, -10)


Line (-40, 0)-(40, 0), vbBlue
Line (0, -10)-(0, 10), vbBlue
Form1.SetFocus

Print "Simulation of closed-loop system with `live input'"
Print "Phase-plane is shown - velocity against position"
Print

Print "Press number keys 0 to 9 to change the target, q to quit"
'
   dt = 0.05          'Make dt larger to speed up running
   b = 0.1
   x = 40             'Initial values
   v = 0
   t = 0
   Target = 0       'until a key is pressed
   PSet (x, v)        'move to the first point
   Do
      a$ = inkey$
      inkey$ = ""
      If a$ <> "" Then Target = 4 * Val(a$) - 20
     
      u = f * (Target - x) - d * v          'u is determined by feedback

      x = x + v * dt                        'This is the simulation
      v = v + b * u * dt                    '
      t = t + dt
     
      Line -(x, v)                          'This displays the result
      DoEvents
   Loop Until a$ = "q"
   End
'

End Sub