# Why am I not seeing all my graphics?

I write a function to simulate a trajectory,code as below:

PlaneSimulation[px_, py_] := Manipulate[
Module[
{L1, L2, θ1, θ2, c2, s2, c1, s1, RobotInverse,
RobotAera, RobotTrajectory},
L1 = 35; L2 = 16;
c2 = (-L1^2 - L2^2 + px^2 + py^2)/(2 L1 L2);
s2 = -Sqrt[1 - (c2^2) ];
c1 = -((-L1 px - c2 L2 px - s2 L2 py)/(px^2 + py^2));
s1 = -((s2 L2 px - L1 py - c2 L2 py)/(px^2 + py^2));
θ2 = ArcTan[c2, s2] // Simplify;
θ1 = ArcTan[c1, s1] // Simplify;
RobotInverse = Graphics[
{Line[{{0, 0}, {L1 Cos[θ1],
L1 Sin[θ1]}, {L1 Cos[θ1] +
L2 Cos[θ1 + θ2],
L1 Sin[θ1] + L2 Sin[θ1 + θ2]}}],
Blue, PointSize[Medium],
Point[{L1 Cos[θ1], L1 Sin[θ1]}],
Green, PointSize[Medium],
Point[{L1 Cos[θ1] + L2 Cos[θ1 + θ2],
L1 Sin[θ1] + L2 Sin[θ1 + θ2]}]},
Axes -> True, PlotRange -> {{-60, 60}, {-60, 60}},
AspectRatio -> Automatic];
RobotAera =
ParametricPlot[{L1 Cos[θ1] + L2 Cos[θ1 + θ2],
L1 Sin[θ1] +
L2 Sin[θ1 + θ2]}, {θ1, -(5/9) \[Pi],
5/9 \[Pi]}, {θ2, -(5/6) \[Pi], 5/6 \[Pi]},
AspectRatio -> Automatic, ImageSize -> 450];
RobotTrajectory =
ParametricPlot[{px /. t -> u, py /. t -> u}, {u, 0.01, t}];
Show[{RobotInverse, RobotAera, RobotTrajectory}]],
{t, 0, 18}]


Call the function:

Circle:

PlaneSimulation[30 + 10 Cos[20 \[Degree] t],
25 + 10 Sin[20 \[Degree] t]]


Sine:

PlaneSimulation[30 + 10 Sin[20 \[Degree] t], t + 10]


However,the graphic of RobotTrajectory cannot show correctly?

-

PlaneSimulation[px_, py_] :=
Manipulate[
Module[{L1, L2, θ1, θ2, c2, s2, c1, s1, RobotInverse,  RobotAera, RobotTrajectory},
L1 = 35; L2 = 16;
c2 = (-L1^2 - L2^2 + px^2 + py^2)/(2 L1 L2);
s2 = -Sqrt[1 - (c2^2)];
c1 = -((-L1 px - c2 L2 px - s2 L2 py)/(px^2 + py^2));
s1 = -((s2 L2 px - L1 py - c2 L2 py)/(px^2 + py^2));
θ2 = ArcTan[c2, s2] // Simplify;
θ1 = ArcTan[c1, s1] // Simplify;
RobotInverse =
Graphics[{Line[{{0, 0}, {L1 Cos[θ1],  L1 Sin[θ1]}, {L1 Cos[θ1] +
L2 Cos[θ1 + θ2], L1 Sin[θ1] + L2 Sin[θ1 + θ2]}}], Blue,
PointSize[Medium], Point[{L1 Cos[θ1], L1 Sin[θ1]}], Green,
PointSize[Medium], Point[{L1 Cos[θ1] + L2 Cos[θ1 + θ2],
L1 Sin[θ1] + L2 Sin[θ1 + θ2]}]},
Axes -> True, PlotRange -> {{-60, 60}, {-60, 60}},
AspectRatio -> Automatic] /. t -> w;
RobotAera =
ParametricPlot[{L1 Cos[θ1] + L2 Cos[θ1 + θ2], L1 Sin[θ1] + L2 Sin[θ1 + θ2]},
{θ1, -(5/9) π, 5/9 π}, {θ2, -(5/6) π, 5/6 π},
AspectRatio -> Automatic, ImageSize -> 450];
RobotTrajectory =  ParametricPlot[{px, py} /. t -> u, {u, 0.01, w},
PlotStyle -> Red, PlotLabel -> px];
Show[{RobotInverse, RobotAera, RobotTrajectory}]], {w, 0, 18}];
PlaneSimulation[30 + 10 Cos[20 ° t], 25 + 10 Sin[20 ° t]]


-
,Thanks,but I wonder why add the pattern  t -> w can achieve good result? – user123 May 5 '14 at 4:56