Static Stability Analysis of Hexagonal Hexapod Robot for the Periodic Gaits†


Abstract –Hexagonal hexapod robot is a flexible mechanical robot with six legs. Ithas the ability to walk over terrain. The hexapod robot likes insect so it has the sameperiodic gaits. These gaits are tripod, wave and ripple gaits. Hexapod robot needs tostay statically stable at all the times during each gait in order not to fall with three ormore legs continuously contacts with the ground. The safety static stability walking canbe indicated by the stability margin. In this paper we based on the forward, inversekinematics for each hexapod’s leg to simulate the hexapod robot model walking for allperiodic gaits and the geometry in order to derive the equations of the sub-constraintworkspaces for each hexapod’s leg. They are defined as the sub-constraint workspacesvolumes when the legs are moving without collision with each other and they are usefulto keep the legs stable from falling during each gait. A smooth gait was analyzed andenhanced for each hexapod’s leg in two phases, stance phase and swing phase. Theequations of the stability margins are derived and computed for each gait. Thesimulation results of our enhanced path planning of the hexapod robot approach whish’sinclude all the gaits are statically stable and we are compared between all stabilitymargins for each gait. In addition, our results show clearly that the tripod gait is thefastest gait while the wave and the ripple gaits are more stable than the tripod gait butthe last one has less peaks of stability margins than others.