From: The AMP-Foot 3, new generation propulsive prosthetic feet with explosive motion characteristics: design and validation
\(L_1\) = 70 mm
\(L_2\) = 40 mm
\(L_3\) = 103 mm
\(L_4\) = 60 mm
\(k_{PF}\) = 300 N/mm
\(k_{PO}\) = 180 N/mm