Basic Considerations on Degrees of Freedom of Multi-Legged Locomotion Machines

Abstract

All multi-legged locomotion machines that do not need any dynamic balance control can be classified into several levels functionally. The authors define (i) two dimensional walking, (ii) to maintain the body horizontal on rough terrain, (iii) to keep the absolute height of main body constant as the minimum walking functions of multi-legged locomotion machines.
By the way, how many active degrees of freedom are necessary and sufficient to realize the above functions? Although the consideration of degrees of freeedom seems to be fundamental in developing multi-legged locomotion machines, this problem has not yet been studied thoroughly.
From this point of view, the active degrees of freedom are examined in this paper using a four-legged machine which offers the minimum number of legs capable of keeping static stability. Resultantly it is shown that“six”is the necessary and sufficient number of active degrees of freedom to realize the above functions.