Biomimetic centering for undulatory robots

Substantial work exists in the robotics literature on the mechanical design, modeling, gait generation and implementation of undulatory robotic prototypes. However, there appears to have been relatively limited work on closing the control loop for such robotic locomotors using sensory information from on-board exteroceptive sensors, in order to realize more complex undulatory behaviors. In this paper we consider a biologically inspired sensor-based "centering" behavior for undulatory robots traversing corridor-like environments. Such behaviors have been observed and studied in bees, and robotic analogs were originally developed for non-holonomic mobile robots. Adaptation to the significantly more complex dynamics of undulatory locomotors highlights a number of issues related to the use of sensors (possibly distributed over the elongated body of the mechanism) for the generation of reactive undulatory behaviors and also related to biomimetic neuromuscular control and to the formation control of multi-undulatory swarms. These issues are explored in simulation by means of computational tools specifically geared towards undulatory locomotion in robotics and biology. Moreover, a series of undulatory robotic prototypes has been developed, which are able to propel themselves on a variety of hard and granular substrates, by means of both head-to-tail ("eel-like") and tail-to-head ("polychaete-like") undulatory waves. The undulatory centering behavior is demonstrated experimentally in several layouts of corridor-like environments using these robotic prototypes equipped with infrared distance sensors.