lego walker parametrization

AC

b

a

c

d

d = 3 (slider from 0 to 7)
c = 1.58 (slider from 1 to 5, step 0.01)
b = 2 (slider from 1 to 5)
α = 0 rad (slider from 0° to 360°, step 5°)
B0: (1, 0)
A: (0, 0)
B = Rotate(B0, α, A)
d_1 = Circle(B, b)
a = 2 (slider from 1 to 5, step 0.1)
C: (a, 0)
e = Circle(C, c)
D = Intersect(d_1, e, 2)
f = Segment(B, D)
D'_1 = Dilate(D, 1 + d / b, B)
h = Segment(A, C)
i = Segment(A, B)
j = Segment(D, C)
β = -1.658062789394613 rad (slider from -120° to 120°, step 5°)
E = Rotate(D'_1, β, D)
g = Segment(D, E)
sted1 = Locus(E, α)
B' = Mirror(B, A)
d2 = Circle(B', b)
D' = Intersect(e, d2, 1)
D'2 = Dilate(D', 1 + d / b, B')
E' = Rotate(D'2, β, D')