enter image description here

Don’t know how to solve this problem.

Just doing simulation of four-stroke cycle, when debugging a “System.ArgumentException” occurs.

Private Sub Animation(q2)
    Dim MyGraphics As Graphics
    MyGraphics = Me.CreateGraphics
    Dim Mycolor As Color = Color.FromArgb(0, 255, 0)
    Dim MyPen As New Pen(Color.Green, 1)
    Dim ox, oy, ax, ay, bx, by, crank_length, conrod_length
    Dim k
    Dim q, r As Integer
    MyGraphics.Clear(Color.WhiteSmoke)
    Call position_analysis(q2)
    k = 800
    crank_length = r2 * k
    conrod_length = r3 * k
    '------------------
    ox = 150
    oy = 300
    ax = ox + crank_length * Math.Cos(q2)
    ay = oy - crank_length * Math.Sin(q2)
    bx = ax + conrod_length * Math.Cos(q3)
    by = oy
    '------------------
    r = crank_length
    q = q2 * 180 / pi
    If q > 360 Then q = q - 360
    q = 360 - q
    MyGraphics.DrawArc(MyPen, ox - r, oy - r, 2 * r, 2 * r, q, 90)
    '-------------------
    LineShape1.X1 = ox
    LineShape1.Y1 = oy
    LineShape1.X2 = ox + crank_length + conrod_length + 100
    LineShape1.Y2 = oy
    LineShape2.X1 = ox
    LineShape2.Y1 = ox
    LineShape2.X2 = ax
    LineShape2.Y2 = ay
    LineShape3.X1 = ax
    LineShape3.Y1 = ay
    LineShape3.X2 = bx
    LineShape3.Y2 = by
    OvalShape1.Location = New Point(ox - OvalShape1.Width / 2, oy - OvalShape1.Height / 2)
    OvalShape2.Location = New Point(ax - OvalShape2.Width / 2, ay - OvalShape2.Height / 2)
    OvalShape3.Location = New Point(bx - OvalShape3.Width / 2, by - OvalShape3.Height / 2)
    RectangleShape1.Location = New Point(bx - RectangleShape1.Width / 2, by - RectangleShape1.Height / 2)
End Sub

enter image description here

Change $exception into Mygraphics