Off[General::"spell"]
Off[General::"spell1"]

MotiPoin[A_, B_, C0_, r0_, theta0_, b_, alpha_] :=
Module[{q0, trif, K2, T, h, eq},
q0 = (C0 r0 Tan[theta0])/B;
trif = (2 \[Pi] B)/(r0 (A Cos[theta0] + C0 Sin[theta0] Tan[theta0]));
K2 = (B q0)^2 + (C0 r0)^2;
T = 1/2 (B q0^2 + C0 r0^2);
h = Sqrt[(2 T)/K2];
eq1 = Derivative[1][p][t] == ((B - C0) q[t] r[t])/A;
eq2 = Derivative[1][q][t] == ((C0 - A) p[t] r[t])/B;
eq3 = Derivative[1][r][t] == ((A - B) p[t] q[t])/C0;
eq4 = Derivative[1][psi][t] == (Cos[phi[t]] q[t] + p[t] Sin[phi[t]])/Sin[theta[t]];
eq5 = Derivative[1][phi][t] == r[t] - Cot[theta[t]] (Cos[phi[t]] q[t] + p[t] Sin[phi[t]]);
eq6 = Derivative[1][theta][t] == p[t] Cos[phi[t]] - q[t] Sin[phi[t]];
w1 = (Cos[phi[t]] Cos[psi[t]] - Sin[phi[t]] Sin[psi[t]] Cos[theta[t]]) p[t] - (Cos[psi[t]] Sin[phi[t]] + Cos[phi[t]] Cos[theta[t]] Sin[psi[t]]) q[t] + r[t] Sin[psi[t]] Sin[theta[t]];
w2 = (Cos[psi[t]] Cos[theta[t]] Sin[phi[t]] + Cos[phi[t]] Sin[psi[t]]) p[t] + (Cos[phi[t]] Cos[psi[t]] Cos[theta[t]] - Sin[phi[t]] Sin[psi[t]]) q[t] - Cos[psi[t]] r[t] Sin[theta[t]];
w3 = Cos[theta[t]] r[t] + Cos[phi[t]] q[t] Sin[theta[t]] + p[t] Sin[phi[t]] Sin[theta[t]];
sol = NDSolve[{eq1, eq2, eq3, eq4, eq5, eq6, p[0] == 0, q[0] == q0, r[0] == r0, psi[0] == 0, phi[0] == 0, theta[0] == theta0}, {p, q, r, psi, phi, theta}, {t, 0, b trif}];
{x, y} = Flatten[{-((w1 h)/w3), -((w2 h)/w3)} /. sol];
z = x^2 + y^2;
If[A < C0 < B || B < C0 < A, Goto[2], Goto[1]];

Label[1];
m = FindMinimum[z, {t, 0, 0, b trif}];
M = FindMinimum[-z, {t, 0, 0, b trif}];
ra1 = Sqrt[m[[1]]];
ra2 = Sqrt[-M[[1]]];
Print["L'erpoloide è contenuta in una corona circolare"];
Print["avente raggio interno ra1 e raggio esterno ra2"];
Print["ra1=", ra1]; Print["ra2=", ra2];
c1 = ParametricPlot[{ra1 Sin[u], ra1 Cos[u]}, {u, 0, 2 \[Pi]}, AspectRatio -> 1, DisplayFunction -> Identity, PlotStyle -> RGBColor[0.8669, 0.258, 0.227]];
c2 = ParametricPlot[{ra2 Sin[u], ra2 Cos[u]}, {u, 0, 2 \[Pi]}, AspectRatio -> 1, DisplayFunction -> Identity, PlotStyle -> RGBColor[0.925, 0.140, 0.129]];
Plot[Sqrt[z], {t, 0, b trif}, AxesLabel -> {"t", "ra"}];
erp = ParametricPlot[{x, y}, {t, 0, b trif}, AspectRatio -> 1, PlotRange -> All, DisplayFunction -> Identity];
Show[erp, c1, c2, DisplayFunction -> $DisplayFunction];
Goto[3];

Label[2];
Plot[Sqrt[z], {t, 0, b trif}, AxesLabel -> {"t", "ra"}];
erp = ParametricPlot[{x, y}, {t, 0, b trif}, AspectRatio -> 1, PlotRange -> All];

Label[3];
xp = p[t]/Sqrt[2 T] /. sol;
yp = q[t]/Sqrt[2 T] /. sol;
zp = r[t]/Sqrt[2 T] /. sol;
X = (Cos[u] Sin[v])/Sqrt[A];
Y = (Sin[u] Sin[v])/Sqrt[B];
Z = Cos[v]/Sqrt[C0];
el = ParametricPlot3D[{X, Y, Z}, {u, 0, 2 \[Pi]}, {v, 0, alpha}, LightSources -> {{{-1, -1, 3}, GrayLevel[0.999]}}, Boxed -> False, DisplayFunction -> Identity];
pol = ParametricPlot3D[Evaluate[Flatten[{xp, yp, zp}] /. sol], {t, 0, b trif}, PlotPoints -> 200, DisplayFunction -> Identity];
Show[el, pol, DisplayFunction -> $DisplayFunction];
]

MotiPoin[1,1.5,0.5,3,Pi/4,1.5,Pi/4]
MotiPoin[1, 1.5, 0.5, 3, 0.01, 1.5, Pi/100]
MotiPoin[0.5, 1.5, 1, -3, 0.01, 3.5, Pi]
MotiPoin[1, 1, 1.5, 3, Pi/4, 2.5, Pi/2]