Numerical and experimental study of the virtual quadrupedal walking robot-semiquad

摘要

SemiQuad is a prototyped walking robot with a platform and two double-link legs. Thus, it is a five-link mechanism. The front leg models identical motions of two quadruped's front legs, the back leg models identical motions of two quadruped's back legs. The legs have passive (uncontrolled) feet that extend in the frontal plane. Due to this the robot is stable in the frontal plane. This robot can be viewed as a "virtual" quadruped. Four DC motors drive the mechanism. Its control system comprises a computer, hardware servo-systems and power amplifiers. The locomotion of the prototype is planar curvet gait. In the double support our prototype is statically stable and over actuated. In the single support it is unstable and under actuated system. There is no flight phase. We describe here the scheme of the mechanism, the characteristics of the drives and the control strategy. The dynamic model of the planar walking is recalled for the double, single support phases and for the impact instant. An intuitive control strategy is detailed. The designed control strategy overcomes the difficulties appeared due to unstable and under actuated motion in the single support.