Abstract: Based on the asymmetry principle of the animal limb motion, a double-half-revolution mechanism is proposed, which can imitate walking movement effect, and is comprised of one first swiveling arm, one second swiveling arm and two striding rods. Through gait analysis of mechanism motion, their motion coupling relations among the joints are obtained. By analyzing the rods geometric relations when they rotate, the stagnation points and inherent characteristic line of double-half-revolution mechanism are found out. Based on the walking motion characteristics of double-half-revolution mechanism, two configuration schemes for wheel-legged mechanism are proposed: ipsilateral offset type and bilateral division type. The ipsilateral offset configuration scheme adopts two tandem planetary gear trains to achieve the motion characteristics of double-half-revolution mechanism, the first swiveling arm and second swiveling arm are their planet carriers (also as gearbox casings) of the planetary gear trains. Based on interference analysis, its non-interference condition is obtained. The bilateral division configuration scheme adopts double crank four-bar linkage mechanism to achieve the inherent geometric characteristics of double-half-revolution mechanism. Based on motion simulation in COSMOS Motion software, the motion trail curves of joints of the wheel-legged mechanism are obtained, and its fluctuation is analyzed. Through making experiments by the wheel-legged mechanism prototype, its dynamic movement performance is verified.

Key words: Double-half-revolution mechanism, Interference analysis, Motion characteristics, Motion simulation, Wheel-leg configuration