Material or article handling – Article manipulator moves analogous with human hand – finger,... – Electric or fluid motor drive for manipulator
Reexamination Certificate
1999-09-17
2002-05-28
Ellis, Christopher P. (Department: 3651)
Material or article handling
Article manipulator moves analogous with human hand, finger,...
Electric or fluid motor drive for manipulator
C700S213000
Reexamination Certificate
active
06394731
ABSTRACT:
The disclosure of Japanese Patent Application No. HEI 10-263348 filed on Sep. 17, 1998 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an art for assisting an operator in carrying heavy articles, with which an operator is able to carry heavy articles using an assist device while feeling as if he were carrying a light article.
2. Description of the Related Art
Many attempts have been made for the realization of the above-mentioned art. An example is disclosed in “Control of Man-Machine System Based on Virtual Tool Dynamics ” (Kazuhiro KOSUGE, Yoshio FUJISAWA and Toshio FUKUDA, Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 60, No. 572 (1994-4) pp. 211-217). It is reported, that when the actuator output is controlled by a human in a robot cooperation system so that the equation,
M
v
d
2
x/dt
2
+D
v
dx/dt+K
v
x=Q F
h
−F
e
is satisfied, when an operator is working in cooperation with a robot, the operator is able to perform the work as if he were using a tool for amplifying the operating force of such tools as a nail puller, a pair of pincers, and a wrench. In the above equation, M
v is
the mass matrix of a virtual tool, D
v
is the matrix of viscosity coefficient, and K
v
is the spring constant matrix, each being an n×n matrix. Q is the magnification for amplifying the force of an operator, F
h
is the operating force of the operator, F
e
is the force applied to an object article by a manipulator, and x is the position of the object article. Further, M
v
, D
v
, and K
v
are values determined based on the characteristics of tools equivalent to the robot from the standpoint of an operator.
In the art “Motion Generation of Robot in Cooperation with Human” (Kazuhiro KOSUGE and Norihide KAZAMURA) in Transactions of the Fifteenth Japan Robot Society Sessions, pp. 393-394, there is disclosed a carrying system wherein human and robot cooperate to carry articles, an actuator output is controlled so that the equation,
M
v
d
2
x/dt
2
+D
v
dx/dt+K
v
x=F
h
is satisfied. Further, the values of M
v
, D
v
, K
v
, and the like were varied to experimentally confirm the change in operability in a system where human and robot cooperate to carry articles. According to the results thus reported, it is easier to carry the articles smoothly when a larger coefficient for acceleration d
2
x/dt
2
(mass matrix M
v
of the virtual tool) is taken (referred to as an impedance control), and it is easier to move the articles by small notches when a larger coefficient for speed dx/dt (matrix of viscosity coefficient D
v
) is taken (referred to as damping control). Conversely, it is reported that it is difficult to move the articles in small notches during impedance control and that it is difficult to move the articles smoothly and substantially linearly during damping control. It is further reported that the mass matrix M
v
and the matrix of viscosity coefficient D
v
needs to be adjusted to proper values depending on the type of cooperation work conducted. Also, the spring constant matrix K
v
is set to 0 in the report, because a spring force, which changes according to the position, ordinarily does not act when carrying an article. However, the spring constant matrix K
v
cannot be set to 0 when carrying an article subject to spring force and therefore, it can be easily apprehended that there exists an appropriate value for spring constant matrix K
v
for providing a good operability.
A series of papers described above report a realization of good-quality work, without giving an operator a disagreeable feeling, by providing a behavior equivalent to that when force amplification tool such as a nail puller is employed by using an assist force of a robot. Also, it is reported that a tool capable of realizing equivalent characteristics depending on the type of work needs to be selected, so that casually selecting the mass matrix M
v
, matrix of viscosity coefficient D
v
, spring constant matrix K
v
, and the like leads to working with inappropriate tool for intended work. This results in difficulty of accurately positioning an article at a target position after carrying the article smoothly near the target position, in the case of carrying the articles. The locus of the article until it is carried near the target position tends to be zigzag rather than a smooth line. Accordingly, it is reported that it is necessary to change the control method for the assist force needs to be changed.
“Experimental Evaluation for a Robot Carrying an Object with a Human” (Ryojun IKEURA, Haruaki KOZAWA and Kazuki MIZUTANI, Japan Society of Mechanical Engineers No.
98-4
Robotics-Mecbatronics Sessions 98 Transactions 2AIII-3(1) to (2) ) discloses a recognition that it is necessary to change the viscosity coefficient (described as damping coefficient) established between the operating force of an operator and the speed of the article during a work to construct a cooperation system free from disagreeableness. To this end, a method for altering the viscosity coefficient according to the time lapsed from the start is proposed by this paper.
The first and the second papers described earlier indicate important views in constructing a cooperation system that does not make an operator feel disagreeable, and have made great achievements. However, because the system stands on the ground of using an equivalent tool, no consideration is made as to the view corresponding to exchange of tools during a series of work.
In the third paper mentioned earlier, changing of the viscosity coefficient according to time lapsed is discussed, which almost corresponds to sequentially changing tools during work. However, there is no general consideration as to what characteristics to give to what work. Further, because the analysis result is based on only one type of work, it contains no information on how to change the mechanical properties of the assist device when the content of work is changed. Further, the object to be changed timewise is limited to the viscosity coefficient (equivalent to mass) and therefore the proportional coefficient established between the acceleration and force proportional to acceleration is not considered.
SUMMARY OF THE INVENTION
The present invention has been made to improve the state of the art, and it makes a new proposal for how to change the mechanical properties during a series of work.
It was also found that it is necessary that an operator feels appropriate reaction force in realizing the aforementioned good work, and still further, it is necessary to change the reaction force pattern required by the operator according to the content of work, task process phase, operator, work duration, experience, state of fatigue of the operator, and the like. Therefore, another object of the present invention is to realize a work assist device which satisfies such requirements.
According to a first aspect of the present invention, the work assist device includes a movable body for supporting heavy articles, an actuator for actuating the movable body, and a controller for controlling the output of the actuator. The controller controls the output of the actuator such that the relationship between the force applied to the movable body by the operator and the movement of the heavy article realized through the movement of the movable body is equivalent to the relationship between the force generated by application of the equivalent force to a virtual article placed in a free space and which is lighter than the heavy article and the movement created thereby. Further, the controller adjusts the actuator output such that the equivalent mass of the virtual article fluctuate during a series of carrying work.
According to the first aspect, the output of the actuator is adjusted when an operator applies operating force to the movable body. Then, the operating force of the operator (referred to as reaction force) together wit
Konosu Hitoshi
Yamada Yoji
Ellis Christopher P.
Pillsbury & Winthrop LLP
Toyota Jidosha & Kabushiki Kaisha
Tran Khoi H.
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