Analysis of behavior based control for planetary cliff descent using cooperative robots
Erik Mumm, Shane M Farritor, Terrance L. Huntsberger, Paul S. Schenker · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2003
Future robotic planetary exploration will need to traverse geographically diverse and challenging terrain. Cliffs, ravines, and fissures are of great scientific interest because they may contain important data regarding past water flow and past life. Highly sloped terrain is difficult and often impossible to safely navigate using a single robot. This paper describes a control system for a team of three robots that access cliff walls at inclines up to 70°. Two robot assistants, or anchors, lower a third robot, called the rappeller, down the cliff using tethers. The anchors use actively controlled winches to first assist the rappeller in navigation about the cliff face and then retreat to safe ground. This paper describes the control of these three robots so they function as a team to explore the cliff face. Stability requirements for safe operation are identified and a behavior-based control scheme is presented. Behaviors are defined for the system and command fusion methods are described. Controller stability and sensitivity are examined. Controller performance is evaluated with simulation and a laboratory system.