Control of the Variable-Structure-Type Locomotive Robot : Walking Forms and Controlling Methods of the Leg-Leg Type

We have developed a variable-structure-type locomotive robot which can employ three variations of locomotive style according to the working environment or application of the robot. In a previous study, we described the concept of the variable-structure-type locomotive robot, the controlling methods and the experimental results on the first variation. In this investigation, the leg-leg type, which is a type of quadruped walking robot, is reported. Two forms of walking are proposed. One is the "rub" gait in which each pair of legs is always in contact with the ground and walking is achieved by rubbing or slipping while moving the forelegs and hindlegs alternately. This locomotive style is advantageous in maintaining body stability. The other is the "bound" gait in whith two pairs of legs kick back against the ground simultaneously in order to propel the robot. It has been experimentally confirmed that both forms of locomotion are useful in the leg-leg type, and high-speed translation can be attained by the "bound" gait. The control method for the step width proposed here for the "bound" gait proved effective in providing the robot with a constant-width-step walk, independent of environmental conditions and slope of the ground.