Bio-mimetic walking with distributed controlled wave gait

Abstract

This paper describes a multi-agent mobile system that walks. In particular, the gate of the system can be considered as an expansion of the ordinary wave gate, since the class of system configuration is not restricted in a line shape. The system consists of a number of identical units with distributed controllers. The homogeneous units are mechanically connected to construct a mobile platform. Every unit has its local controller that communicates only with its adjacent units. This basic configuration of supervisor-less structure affirmatively confines the dependence of each unit to a local area, and therefore any unit can be removed from/add into any part of a system regardless of the timing without disturbing the performance of the whole system. This flexibility of configuration significantly contributes to easy maintenance of units, such as battery charging or hot-replacing for faulty units. Utilizing the flexibility as well, the system is capable of adapting to a variety of tasks including transportation application and to target objects having various kinds of shape and/or a wide range of mass. A proposed example unit contains a Gough-Stewart Platform, a symmetrical type of parallel link manipulator, as its leg. The whole mobile system is aimed at transportation platform, with high system flexibility, i.e., the system is able to adapt to wide range of target objects. The “digital actuation (D-actuation)” concept is applied to the local unit controller. D-actuation is a concept to drive a mechatronic system with numbers of “digital actuator (D-actuator)” that has only discrete stable states, such as pneumatic cylinders or solenoids. D-actuation yields great benefits: high repeatability, system simplicity, and low cost. Because of the simplicity of the communication data, the control strategy, and the concept of D-actuation, the controlling framework can be implemented as distributed and localized one on every unit. The Schlafli symbol is applied to denote the system configurations. For example, two-dimensional honeycomb like connection of the units is denoted as {3,6}. A simple, but effective, coordinate system, HC/P (HoneyComb by Projection), is introduced to denote the connecting relations among the units in the {3,6} system. In short, HC/P utilizes three-axes to describe 2D system, and the redundant triplet notation enables direct and clear computation regarding unit coordinates. The basic architecture of the unit mechanism and gait controller are justified with simulation results. The performed simulation shows the feasibility of the whole mobile system.