Comparative analysis of a geometric and an adhesive righting strategy against toppling in inclined hexapedal locomotion

Animals are known to exhibit different walking behaviors in hilly habitats. For instance, cats, rats, squirrels, tree frogs, desert iguana, stick insects and desert ants were observed to lower their body height in traversing slopes, whereas mound-dwelling iguanas and wood ants tend to maintain constant walking kinematics regardless of the slope.
This paper aims to understand and classify these distinct behaviors into two different strategies against toppling for climbing animals by looking into two factors, (i) the torque of the center of gravity (CoG) with respect to the critical tipping axis, and (ii) the torques of the legs, which have the potential to counterbalance the CoG-torque. Our comparative locomotion analysis on level locomotion and inclined locomotion exhibited that primarily only one of the proposed two strategies was chosen for each of our sample species, despite the fact that a combined strategy could have reduced the animal's risk to topple over even more. We found tha...