Abstract
A quadruped walking has been studied in the field of biological science and engineering mainly, since it is one of the most popular locomotion method of animals, and also has the functional adaptability for rough terrain. But when the quadruped studies are compared with the biped ones, it may be found that the experiment is more difficult with a quadruped because animals are hard to treat and their forms and sizes are different. In view of this, we attempt to introduce the computer simulation method in the quadruped studies.
The proposed mathematical model of quadruped is the first one in our plan. The model is able to correct the given motions of legs in order to maintain the static stability and to calculate the posture and position of the quadruped against a terrain. In illustrations of the application of this system, the crawl gaits of elephant and dog were simulated and kinematically analyzed by widely altering of parameters. Consequently, the following characteristics of quadruped walking became clear; 1) the displacement of the scapula and pelvis with walking effectively reduces the sway of the body, 2) the inclined posture of animals at slope is effective to hold on their walking rhythm as well as to increase the static stability, 3) there is a close relationship between the position of the centre of gravity and the walking cycle, by which animals can move naturally to a dynamic stability from a resting posture.
We desire that these simulation studies will be a new means with respect to the analysis of walking systems, and that those results will be applied to the design of a prosthesis or a legged vehicle.
