Optimal design for passive robot in rough terrain based on VCM

The mechanism with the characteristics of virtual center of motion (VCM) is one of the limited degree of freedom (DOF) mechanisms substantively. The VCM was employed in robots which were mobile on rough terrain for its special characteristics. The front mechanism was optimized through analyzing the relation of the VCM and the center of the front wheel. The static model of the robot was simplified for the character of VCM. According to the static analysis, the parameter and the position of the spring suspension on the front mechanism were optimized through minimizing the friction coefficient of the wheels. The ground contact of all wheels at any time was guaranteed by the spring. An optimized prototype was designed and manufactured. It is able to passively overcome obstacles of up to 2.1 times of its wheel diameter and can climb stairs with steps of over 1.27 times. The advance of the passive adaptation in rough terrain was shown in the contrastive experiments.