Energy comparison between trot, bound, and gallop using a simple model.
ABSTRACT In this paper, the dynamics of quadruped trot, gallop, and bound will be examined using a simple model for the quadruped. The body of the quadruped is modeled as a uniform bar and the legs are modeled by massless springs. It will be shown that symmetry can be used to study the locomotion of this system. Using symmetry, a technique will be developed to obtain periodic solutions for each of the gaits of the quadruped model. These periodic solutions will be computed at various speeds. The energy levels will be compared for each of the gaits. The exchange of energy between its different forms will be shown for different gaits. It will be shown that even without body flexibility, there are significant savings in energy due to gait transition from trot to gallop. The energy levels will be used to predict the trot-gallop transition speed. These results will be compared with the experimental results for horses and dogs.
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ABSTRACT: Previous studies have noted that biological quadrupeds adjust their gaits when encountering drag in their locomotion. This paper in- vestigates the hypothesis that these gait adjustments allow the legs to operate at an optimal working length when generating thrust. A 5-DoF dynamic model of a quadruped having a rigid trunk and massless legs is formulated. This model reflects the dimensions and inertial properties of a galloping machine the authors are design- ing. The constrained, steady-state motion equations governing the transverse and rotary gallops of the model are solved numerically for various levels of drag. The footfall phasing solutions for both forms of the gallop approach a partially in-phase gait, the half-bound, as drag increases. These gait transitions are the result of constraints requiring the legs to operate at their optimal working length when in contact with the terrain. Thus, the behavior of the model supports the original hypothesis. This paper also includes a discussion of future research directions in the field of artificial legged locomotion. KEY WORDS—galloping, quadruped, legged vehicles, im- pulse modelThe International Journal of Robotics Research 01/1999; 18:1224-1234. · 2.86 Impact Factor
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ABSTRACT: Gait selection is a strategy used by quadrupeds to meet the demands of locomotion under variable environmental conditions. The movement of black-backed jackals Canis mesomelas within a desert area was investigated. The usage and distribution of gaits in three distinct desert environments in the Namib Desert, Namibia, were analysed. The areas were chosen based on topographical differences: a bare, a featureless sand plain in an interdune valley, a large sand dune and a narrow dune valley with clumped plant growth. Fresh jackal tracks were recorded by GPS once a week for 1 year. Gait types, gait segment lengths and the rate of switches between gaits were analysed. Trot was the most frequently used gait in all areas, followed by walk and the two types of gallop. Jackals used faster gaits, with the lowest number of gait switches in the interdune plain. Movements on the sand dune were characterized by shorter gait segment lengths and frequent gait changes. In the dune valley, movements were slower and the rate of gait changes was intermediate between the other two areas. The strongest influence on gait choice and on gait changes was found to be the terrain topography, mainly the grade. Gait and track choice can be seen as a dynamic adaptation to a demanding environment like the Namib Desert.Journal of Zoology 02/2008; 275(2):124 - 129. · 2.04 Impact Factor