Motor vehicles – Special driving device – Stepper
Reexamination Certificate
2002-03-04
2004-10-12
Morris, Lesley D. (Department: 3611)
Motor vehicles
Special driving device
Stepper
C901S001000
Reexamination Certificate
active
06802382
ABSTRACT:
TECHNICAL FIELD
This invention relates to a legged mobile robot having at least plural movable legs and specifically to a legged mobile robot capable of walking or otherwise performing movement (locomotion) operations with its movable legs on variable road surfaces. More specifically, it relates to a legged mobile robot capable of walking or otherwise performing movement operations with its movable legs on road surfaces, the, surface states of which are unknown, and also to a legged mobile robot capable of performing adaptive legged movement operations depending on prevailing road surface conditions.
BACKGROUND ART
A mechanical apparatus for performing movements simulating the movement of the human being using electrical or magnetic operation is termed a “robot”. The etymology of the term robot is to be “ROBOTA” (slave machine) of the Slavic language. The robots started to be used widely in this country towards the end of sixtieth. Most of the robots used were industrial robots, such as manipulators or transporting robots, aimed at automation or unmanned operations in plants.
The standstill type robot, installed and used at a fixed place, such as armed robots, are in operation only in a stationary or local working space, such as for assembling or sorting of component parts. On the other hand, the mobile robots are not limited as to working space and are movable on a preset or undefined path in an unrestricted fashion to perform operations to take the place of human operators or to offer variegated services to take the place of the human being, dogs or other living organisms. The legged mobile robots, while being unstable and difficult to control as to its orientation or walking, as compared to crawler or tire type robots, are superior in climbing up and down a ladder or a staircase, in riding over obstacles or walking or running flexibly on a leveled or unleveled terrain.
In recent years, researches and development in legged mobile robots, including pet type robots, simulating the bodily mechanism or movements of animals, such as quadruples, e.g., dogs or cats, or so-called humanoid robots, simulating the bodily mechanism or movements of animals erected and walking on feet, such as human being, are progressing, and expectations may be made of practical utilization of these robot types.
The significance of researching and developing the legged mobile robots, termed humanoid robots, may be grasped from, for example, the following two points:
One is the point from the human science. That is, the mechanism of the natural movements of the human being, including the walking, may be clarified scientifically through the process of creating a robot having the structure of legs and/or feet, similar to that of the human being, and of devising its controlling method to simulate the walking movements of the human being. The results of these researches can possibly be fed back to variable fields of researches dealing with the movement mechanism of the human being, such as the fields of human engineering, rehabilitation engineering or sports science.
The other is the development of practically useful robots, supporting the human life as a partner, that is supporting the human activities in various aspects of the everyday life such as in living environment. With the robots of this type, it is necessary to learn the method for adaptation to the human being with different personalities and to different environments as the robots are taught from the human being to make further progress in functional aspects. It may be surmised that, if the, robots are “humanoid”, that is of the same form or structure as the human being, the communication between the human being and the robot will be smoother.
For example, if the robot is to be taught as to a technique of passing through a chamber as he evades an obstacle that he should not tramp, it will be far easier for a user (operator) to teach it in case the robot is the robot walking on two legs than in case the robot is of the completely different structure from the teacher as in the case of the crawler or four-legged robot. Similarly, such a robot would learn more easily. In this respect, see “Control of Robots Walking on Two Feet” of Automobile Technical Association of Japan, Kanto Branch, <KOSO>, No. 25, April 1996.
The working space and the living space of the human being is mostly formed to suit to the bodily mechanism or pattern of behavior of the human being erected and walking on two legs. Stated differently, there exist too many obstacles in the human living space for the mechanical systems of the current technical level having wheels or other driving devices as movement means. In order for the mechanical system, that is the robot, to support or act for the human being in variable human operations and to adapt itself more deeply to the living space of the human being, it is desirable that the movable range of the robot is approximately the same as that of the human being. This accounts for the expectations made of development of practically useful legged mobile robot. The human type configuration of the robot may be said to be indispensable in order for the robot to adapt itself more readily to the human living environment.
A number of proposals have already been made for achieving orientation control or stabilized walking of the robot of the type performing legged movement using two legs. The stable “walking” herein means “movement on feet without tumbling down”.
The stabilized orientation control for a robot is crucial in evading its leveling. The reason is that leveling means interruption of the operation being performed by the robot and considerable time and labor is needed until the robot erects itself from its leveled state to re-initiate the operation, and that, more importantly, the leveling tends to inflict a fatal damage not only to the robot but also the object against which has impinged the robot. Thus, stabilized orientation control and prevention of leveling during walking is most crucial in the engineering and development of the legged mobile robot.
During walking, the force of gravity, the force of inertia and the moment thereof act from the walking system to the road surface due to the force of gravity and the acceleration produced by the walking movement. According to the “d'Alembert's principle”, these are counterbalanced by the reaction of the floor as the reaction from the floor surface to the walking system, that is the reactive moment of the floor. As a conclusion of mechanical inferences, a point of zero pitch axis and roll axis moment, that is a zero moment point (ZMP), exists on or inside a side of a supporting polygon delimited by the contact point of the foot sole with the ground and the road surface.
The majority of proposals so far made for preventing the leveling of the legged mobile robot use this ZMP as the criterium in judging the stability in walking. The generation of a pattern of walking on two legs, derived from the ZMP criterium, has advantages that the ground touching point of the foot sole can be previously set such that kinematic constraint conditions of the foot end in compliance with the road surface can be considered more readily. Moreover, using the ZMP as the criterium in verifying the stability means that not the force but the trajectory is to be handled as a target value in movement control, thus enhancing the technical feasibility. Meanwhile the concept of the ZMP and using this ZMP as the criterium in judging the walking stability of the robot is stated in Miomir Vukobratovic, “Legged Locomotion Robots” (Ichiro KATO, “Walking Robots and Artificial Legs”, published by Nikkan Kogyo Shimbun K K).
However, the legged mobile robot has made but one step from the stage of researches and a number of technical difficulties are still left. For example, the surface states of the road, specifically whether or not the terrain is leveled, or the frictional coefficient, which affects the legged walking significantly, are as yet not tackled sufficiently.
In general, the legged mobile robot perfo
Hattori Yuichi
Yamaguchi Jinichi
Frommer William S.
Morris Lesley D.
Royal, Jr. Paul
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