Optimal Leg Sequencing for a Hexapod Subject to External Forces and Slopes

An optimal leg sequence selection method is developed, which maximizes hexapod robot stability, considering feasible gaits, motion modes, and terrain slope. A novel and fast search method is employed to find the most stable leg sequence for a given gait; if no such sequence exists, the next fastest stable gait is chosen and the most stable leg sequence for this gait is selected. The method can be based on any stability measure; here the Force-Angle Stability Margin criterion is employed that is sensitive to top-heaviness, and inertial and external forces. Results show that the developed method senses instabilities accurately and selects the best leg sequence for maximum stability far faster than exhaustive searches, offering distinct advantages when varied external forces are applied.