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Leg positions during walking on a plane and on thin rods were recorded by photography, videorecording, and videokymography. Joint angles were reconstructed from the tibia-ending position, using a 3-D model of the body. Participation of leg joints in propulsion was analysed by calculating the partial derivatives of tibia end-point position on different joint angles. Adjustment to walking with a narrow ground base is achieved by additional femur depression and flexion of the tibia in the stance phase. In the swing phase, the leg is raised by the same amount as when walking on a plane, but not to the same superior position, as on a plane. The contribution of the subcoxal joint to body propulsion is 64-94% in fore-and middle legs and 22-49% in hind legs. The oblique alignment of the coxal pivot within the thorax helps maintain a long stride for variable ground bases. In Graphosoma, it is close to the optimal position: according to several criteria, the angle between the coxal axis and the body vertical shall be arctan π/2, or ∼ 57.5°.