Comparing effects of rigid, flexible, and actuated series-elastic spines on bounding gait of quadruped robots

Spinal actuation is necessary for quadruped robots to achieve rapid leg locomotion. In this paper, effect of flexible spinal actuation on the bounding gait is investigated. By defining a performance criterion for the bounding gait, a quadruped robot (Ghostdog) is tested in four different case studies; namely rigid spine, flexible passive spine, actuated spine, and series elastic actuated spine. We show that the robot with a series elastic actuator in its spinal joint has the best performance criterion and is the best robot in terms of bounding power consumption. On the other hand, it is shown that by using spinal actuation not only the speed of locomotion increases considerably, but also the pattern of bounding becomes more similar to real fast felines.