Fig. 1.

Schematic diagram showing the morphology of a stick insect leg. Angle $\mathrm{\alpha }$ describes the position of the Thorax-Coxa joint (muscles Protractor-Retractor), angle $\mathrm{\beta }$ stands for the position of the Coxa-Trochanterofemur joint (muscles Levator-Depressor), and angle $\mathrm{\gamma }$ describes the position of the Femur-Tibia joint (muscles Flexor-Extensor). The axis of rotation of the Thorax-Coxa joint is defined by angles $\mathrm{\varphi }$ and $\mathrm{\psi }$ relative to the body-fixed coordinate system (only the vertical axis z is marked). Swing movement and stance movement are sketched by dashed lines. AEP anterior extreme position, PEP posterior extreme position