U.S. patent number 3,927,424 [Application Number 05/435,214] was granted by the patent office on 1975-12-23 for mechanical hand.
This patent grant is currently assigned to Agency of Industrial Science & Technology. Invention is credited to Hideyo Itoh.
United States Patent |
3,927,424 |
Itoh |
December 23, 1975 |
Mechanical hand
Abstract
A mechanical hand comprises a palm element and at least two
finger elements and incorporates a closed link mechanism. The two
finger elements are connected at their basal ends, each with a
joint, the first one to the palm element and the second one to the
forward end of the first finger element, respectively. The closed
link mechanism is constructed of the first finger element in
combination with a projecting bar which stems at a certain angle
from the basal end of the second finger element and constitutes a
unitary part in conjunction with the second finger element. Driving
this closed link mechanism by an actuator sets the finger elements
to movement. When any portion of the finger elements comes into
contact with an obstacle standing in its way, the closed link
mechanism begins to change its form. In consequence of this change
of form, the first finger element and/or the second finger element
begins to turn round the joint as a pivot and continues, while
adapting the form of the mechanical hand to the immediate
environment, to converge in the direction of gradually conforming
to the exterior contour of an object desired to be gripped and
eventually gripping the object.
Inventors: |
Itoh; Hideyo (Tokyo,
JA) |
Assignee: |
Agency of Industrial Science &
Technology (Tokyo, JA)
|
Family
ID: |
11692923 |
Appl.
No.: |
05/435,214 |
Filed: |
January 21, 1974 |
Foreign Application Priority Data
|
|
|
|
|
Jan 19, 1973 [JA] |
|
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48-8431 |
|
Current U.S.
Class: |
623/63; 294/106;
901/36; 414/753.1; 623/26; 901/39 |
Current CPC
Class: |
B25J
15/022 (20130101); A61F 2/583 (20130101) |
Current International
Class: |
B25J
15/02 (20060101); A61F 2/50 (20060101); A61F
2/58 (20060101); A61F 001/06 () |
Field of
Search: |
;3/12-12.8,1.2,1.1
;214/1CM ;294/106 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Frinks; Ronald L.
Attorney, Agent or Firm: Oblon, Fisher, Spivak, McClelland
& Maier
Claims
What is claimed is:
1. A mechanical hand comprising:
a first free rotation joint;
a second free rotation joint;
a third free rotation joint;
a fourth free rotation joint;
a fifth free rotation joint;
a sixth free rotation joint;
a seventh free rotation joint;
a first rod;
a second rod;
a third rod;
a projecting rod;
a projecting bar;
a first finger element;
a second finger element;
a first stationary surface;
a second stationary surface;
said second finger element and said projecting bar being rigidly
joined at a predetermined angle;
said first joint joining said first finger element to said first
stationary surface;
said second joint joining said first finger element to the junction
of said second finger element and said projecting bar;
said third joint joining said first rod and said projecting
bar;
said fourth joint joining said second rod, said first rod and said
projecting rod;
said fifth joint joining said first finger element and said
projecting rod;
said sixth joint joining said second rod to said third rod;
said seventh joint joining said third rod to said second stationary
surface;
whereby an object may be gripped upon the application of pressure
to said third rod.
2. A mechanical hand in accordance with claim 1 wherein two
mechanical hands are symmetrically disposed and joined at said
seventh joint.
3. A mechanical hand in accordance with claim 1, wherein said first
and said fifth joints comprise a single joint joining said first
finger element and said projecting rod and connecting the same to
said first stationary surface.
4. A mechanical hand in accordance with claim 3 wherein two
mechanical hands are symmetrically disposed and joined at said
seventh joint.
5. A mechanical hand comprising:
a first free rotation joint;
a second free rotation joint;
a third free rotation joint;
a fourth free rotation joint;
a fifth free rotation joint;
a sixth free rotation joint;
a seventh free rotation joint;
an eighth free rotation joint;
a ninth free rotation joint;
a tenth free rotation joint;
a first rod;
a second rod;
a third rod;
a fourth rod;
a projecting rod;
a first projecting bar;
a second projecting bar;
a first finger element;
a second finger element;
a third finger element;
a first stationary surface;
a second stationary surface;
said second finger element and said first projecting bar being
rigidly joined at a predetermined angle;
said third finger element and said second projecting bar being
rigidly joined at a predetermined angle;
said first joint joining said first finger element rotatively to
said first stationary surface;
said second joint joining said first finger element and the
junction of said first projecting bar and second finger
element;
said third joint joining said first rod and said first projecting
bar;
said fourth joint joining said second rod, said first rod and said
projecting rod;
said fifth joint joining said projecting rod and said first finger
element;
said sixth joint joining said second rod and said third rod;
said seventh joint joining said third rod and said second
stationary surface;
said eighth joint joining said second finger element and the
junction of said third finger element and said second projecting
bar;
said ninth joint joining said fourth rod and said second projecting
bar;
said tenth joint joining said fourth rod to said first finger
element at a point intermediate the ends of said first finger
element;
whereby an object may be gripped upon the application of pressure
to said third rod.
6. A mechanical hand in accordance with claim 5 wherein two
mechanical hands are symmetrically disposed and joined at said
seventh joint.
Description
BACKGROUND OF THE INVENTION
This invention relates to a mechanical hand. More particularly, the
present invention relates to an adaptable mechanical hand which is
capable of adapting its movement to the immediate environment
within a prescribed range so as to provide stable gripping of a
desired object.
Mechanical hands are generally used as means for loading and
unloading in production lines and as prosthetic hands.
Particularly, mechanical hands which are easy of control and yet
applicable to numerous purposes involving varying working
conditions are in demand.
The mechanical hands heretofore known are such that some require
highly complicated mechanisms in order for them to be adapted to
varying working conditions of numerous purposes and others involve
complicated controls notwithstanding the simplicity of their own
mechanisms. For example, the Belgrade hand, which has long been
known, can have its finger elements easily moved by an actuator.
When any of the finger elements of the Belgrade hand collides with
an obstacle en route to the object to be gripped, however, the hand
can no longer continue its movement, so that the hand cannot grip
the desired object unless the support of the hand is moved to a new
position.
An object of this invention is to provide a mechanical hand which
possesses a mechanism capable of adapting the movement of the
mechanical hand itself to the immediate environment without
requiring any complicated control system and which, therefore,
permits the movement of the mechanical hand to continue until the
desired object is gripped thereby.
Another object of this invention is to provide a mechanical hand
which gradually changes its own form so as to conform to the
contour of the object to be gripped and eventually grip the object
as desired.
SUMMARY OF THE INVENTION
To accomplish the objects described above, the mechanical hand
according to this invention comprises a palm element and at least
two finger elements connected at their basal ends each with a
joint, the first one to the palm element and the second one to the
forward end of the first finger element, respectively, and
incorporates a closed link mechanism composed of the whole or a
part of the first finger element in combination with a projecting
bar stemming at a certain angle from the basal end of the second
finger element and constituting a unitary part in conjunction with
the second finger element, and utilizes an actuator which serves
the purpose of driving the closed link mechanism. The mechanical
hand according to this invention has a construction as described
above. When the mechanical hand is set to movement and any portion
of the finger elements thereof comes into contact with an obstacle
standing in its way, the closed link mechanism begins to change its
form. In consequence of the change in the shape of the link, the
first finger element and/or the second finger element turns round
the joint as a pivot and continues, while adapting the form of the
mechanical hand to the immediate environment, to converge in a
direction for eventually gripping the object to be gripped. When
the mechanical hand comes into contact with the object, the closed
link mechanism functions so as to cause the first and second finger
elements to assume an angular relationship conforming to the
exterior contour of the object, thus providing stable gripping of
the object.
As used in the specification and the claims hereof, the term "basal
end of a finger" means the extremity of the finger element closer
to the palm element and the term "forward end of a finger" means
the extremity of the finger element farther from the palm
element.
Other objects and other characteristics of the present invention
will become apparent from the description which is made in further
detail herein below with reference to the accompanying
drawings.
BRIEF EXPLANATION OF THE DRAWING
FIG. 1(A) is a schematic drawing of the construction of the known
Belgrade hand.
FIG. 1(B) and FIG. 1(C) are explanatory diagrams illustrating the
modes of movement of the Belgrade hand of FIG. 1(A).
FIG. 2(A) is a schematic drawing illustrating one preferred
embodiment of the mechanical hand according to the present
invention.
FIG. 2(B) through (D) are explanatory diagrams illustrating the
modes of movement of the mechanical hand of FIG. 2(A).
FIG. 3 is a schematic drawing illustrating another embodiment of
the mechanical hand according to this invention.
FIG. 4(A) through (C) are explanatory diagrams illustrating the
modes of movement of the mechanical hand as operated to grip an
object laid in a special environment such as, for example, a
groove.
FIG. 5(A) is a schematic drawing illustrating still another
embodiment of the mechanical hand according to the present
invention.
FIG. 5(B) through (D) are explanatory diagrams illustrating the
modes of movement of the mechanical hand of FIG. 5(A).
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1(A) represents a Belgrade hand which has heretofore been
known. To a palm element 1, the first, second and third finger
elements 2, 3 and 4 are connected serially each by means of joints.
Further, a projecting bar 5 stemming at a certain angle from the
basal end of the second finger element 3 has its forward end
connected to the forward end of a rod 6 which in turn is connected
at its basal end to a palm element 1'. Another projecting bar 7
stemming at a certain angle from the basal end of the third finger
element 4 is connected via a rod 8 with a joint to the projecting
bar 9 which stems from the first finger element 2. The finger
elements of this mechanical hand are put to movement when a
projecting bar 10 fastened to the basal end of the first finger
element 2 is driven by means of an actuator (not illustrated).
Since the finger elements are connected each by means of a joint,
their movements are obtained only in a prescribed space. When an
obstacle occurs in any of such prescribed spaces, therefore, the
movements of the finger elements can no longer be obtained beyond
that obstacle. Take, for example, a case in which this mechanical
hand is operated to grip an object 11 laid on a table. If no
obstacle occurs in the spaces for the movements of the finger
elements, then the finger elements turn round their respective
joints until they take a stable grip of the object as illustrated
in FIG. 1(B). If any obstacle occurs in such spaces so that the
mechanical hand comes into contact with the obstacle prior to
reaching the object to be gripped (FIG. 1(C)), however, the
movements of the finger elements are stopped and consequently
prevented from reaching the point of taking a stable grip of the
object. In order for the mechanical hand to grip the object despite
the presence of such obstacle, therefore, it has heretofore been
inevitably necessary for the operator to observe the operation of
the mechanical hand and, whenever such collision of the forward end
of the third finger element against the table top is detected,
change the position of the palm element by suitably moving the base
supporting the hand to a new position at which such collision may
be avoided.
The present invention concerns a mechanical hand possessed of a
mechanism absolutely free from such complicated control of
movement. The preferred embodiment of the invention given in FIG. 2
represents a mechanical hand which possesses two joints. The first
finger element 13 is connected at its basal end with a first free
rotation joint 15 to a first stationary surface, on palm element,
12 and the second finger element 14 is connected at its basal end
with a second free rotation joint 16 to the forward end of said
first finger element 13. A projecting bar 17 stems at a certain
angle from the basal end of the second finger element 14 and
constitutes a unitary part in conjunction with the second finger
element 14. The forward end of the projecting bar 17 is connected
with a third free rotation joint 23 to the forward end of a first
rod 18, whose basal end is connected with a fourth free rotional
joint 24 to the forward end of a projecting rod 19 connected at the
basal end thereof with a fifth joint 21 to the first finger
element. A part of the first finger element 13 goes to make up a
closed link mechanism 20 in conjunction with the projecting bar 17
and the rods 18 and 19. Alternately, the closed link mechanism 20
may be formed by the whole of the first finger element 13 taken in
conjunction with the projecting bar 17 and the rods 18 and 19 as
illustrated in FIG. 3. One end of a second rod 22 is connected to
the joint 24 and the other end of said rod 22 is connected through
a sixth joint 38 to one end of a third rod 25 the other end of
which is connected to a seventh joint 39 of a second stationary
surface, or palm element, 26. The rod 25 is connected via a rod 28
to the piston rod of an actuator 27. In this preferred embodiment,
two mechanical hands of the construction described above are
disposed symmetrically.
In order that the mechanical hands of the present invention having
the aforementioned construction may grip an object 11 as desired,
the rods 28 of the actuator 27 are to be driven downwardly as
illustrated in FIG. 2(B). Consequently, the rods 25 are diverged
and, as the joints 15 are fastened more loosely than any other
joint, the mechanical hands are allowed to turn round the joints 15
as pivots, as illustrated in FIG. 2(B), with the result that the
forward ends of the second finger elements 14 collide into an
obstacle which, in the illustrated case, is a table top. As the
rods 28 of the actuator 27 are further driven downwardly, the
movements of the second finger elements 14 are restricted and the
closed link mechanisms 20 begin to change their form, as shown in
FIG. 2(C), causing the forward ends of the second finger elements
14 to move on the table top toward each other and eventually grip
the object 11, as if embracing it (FIG. 2(D)).
The mechanical hands may be so constructed that they will be first
bent round the joints 16 in the initial stage of operation. At
which pair of joints the mechanical hands are required to be bent
first is a question to be decided at the time of the overall design
in accordance with the object to be gripped and the environment in
which the gripping is to be made. In any event, the mechanical
hands are so designed that the finger elements will eventually
assume an angular relationship most suitable for gripping the
object, as illustrated in FIG. 2(D). The closed link mechanisms 20
serve to provide necessary allowance for the movements of the first
and second finger elements 13 and 14. The motion provided by the
actuator 27 is conveyed, in adequate compliance with the immediate
environment of the operation, to the first or second finger element
by the medium of the closed link mechanisms which function as one
kind of idle element. Because of the idling function of the link
mechanism, the finger elements of the mechanical hands produce
movements well adapted to the environment, including the object to
be gripped, without requiring use of any special control
system.
In this particular example, a piston is employed as the means for
driving the mechanical hands. Alternately, the combination of a
motor and a cam and other suitable known driving means may be
effectively employed as well.
FIG. 4 illustrates the mode of movement of the mechanical hand as
operated to take a grip of an object which is laid in a special
environment, such as, for example, a groove 34. As the actuator
produces a driving motion, the mechanical hands turn round the
joints 15 and cause the forward ends of the second finger elements
14 to come into contact with the table top and then move on the
table top toward each other (FIG. 4(B)). As the forward ends of the
second finger elements 14 reach the edges of the groove 34 and then
fall into the groove, the closed link mechanism 20 immediately
begin to change their form so as to permit the forward ends of the
finger elements to descend slowly toward the bottom of the groove.
As the forward ends of the second finger elements reach the bottom
of the groove, they again begin to move toward each other to
continue their movements for gripping the object. Thus, the
mechanical hands provide the stablest gripping of the object in
much the same way as they are operated to take a grip of an object
laid on a flat surface.
The preferred embodiment illustrated in FIG. 5(A) represents a pair
of mechanical hands each possessed of three joints. In each of the
mechanical hands, a third finger element 29 is connected at its
basal end with an eighth joint 30 to the forward end of the second
finger element of the mechanical hand illustrated in FIG. 2. A
second projecting bar 31 constituting a unitary part with the third
finger element 29 stems at a certain angle from the basal end of
the third finger element. The forward end of the projecting bar 31
is connected with a ninth joint 33 to the forward end of a fourth
rod 32, whose basal end is connected with a tenth joint 37 to the
first finger element.
When an actuator (not illustrated) is operated on the mechanical
hands described above, the rods are diverged relative to the palm
element 26 as illustrated in FIG. 5(B), causing the closed link
mechanisms 20 to change their form. Consequently, the projecting
bars 17 of the second finger elements 14 are turned round the
joints 16, with the result that the second finger elements 14 are
bent with reference to the first finger elements 13. In consequence
of this bending, the closed link mechanisms 20 function to bend the
third finger elements 29 with reference to the second finger
elements 14. As the forward ends of the third finger elements
collide with an obstacle, such as, for example, a table top, the
forward ends of the third finger elements 29 are prevented from
continuing their movement in that direction, with the result that
the revolution of the first finger elements 13 round their
respective joints is stopped. The driving motion of the actuator is
now used in changing the form of the closed link mechanisms 20, so
that the second finger elements 14, and consequently the third
finger elements 29, are turned further. The forward ends of the
third finger elements 29, therefore, move on the table top toward
each other and continue their movements for gripping the object, as
illustrated in FIG. 5(C). There are cases in which the first finger
elements may be revolved in a reverse direction in consequence of
the movement of the forward ends of finger elements toward each
other.
When the forward ends of the finger elements come into contact with
the object, the individual finger elements are bent round their
respective joints so as to take an embracing grip of the object, as
illustrated in FIG. 5(D).
An observation of the movements of a human hand reveals that the
fingers of the human hand in the process of taking a grip at an
object move in three ways: In the first way, the first joints move
mainly during the initial stage and the second and eighth joints
move mainly during the subsequent stage. In the second way, the
second and eighth joints move mainly during the initial stage and
the first joints move mainly during the subsequent stage. In the
third way, all the joints move in a fixed positional relationship.
In any way, the movements of the second and eighth joints are in a
practically proportional relationship, though they are adapted to
the immediate environment in which the gripping operation is in
process. That which specially matters in having the joints of
fingers adapt to greatly varying working conditions is the question
as to what relative movements the first and second joints make. In
the aforementioned mechanical hands each possessed of two joints or
of three joints, therefore, it is extremely important that the
first joint 15 and the second joint 16 should produce movements
adapted to the environment. The adaptable gripping movements of the
finger elements are not particularly affected even if the second
joints 16 and the eighth joints 30 are caused by the closed link
mechanisms to make a interrelated movement. One may rather conclude
safely that the movements of the latter mechanical hands are
similar to the gripping movements of a human hand.
If occasion demands, the second and third finger elements may be
fastened immovably to each other or they may be interlocked to each
other so as to produce movements adapted to the environment
similarly to the aforementioned relationship between the first and
second finger elements.
The preferred embodiments so far described each represent a case in
which two mechanical fingers of an identical construction are
symmetrically disposed. Depending on the purpose of an individual
application, however, two mechanical fingers differing in
construction may be combined and used as one pair. Alternately, one
mechanical finger and a mere rod may be combined so that desired
gripping of an object will be obtained by the cooperation of the
mechanical finger and the rod, with the rod serving the purpose of
holding the gripped object in position in the subsequent process of
lifting.
As is apparent from the foregoing description, the mechanical hands
according to the present invention have closed link mechanisms
which enable the finger elements to produce movements adapted in
fixed spaces to the immediate environment without requiring use of
any complicated control. Because of the adaptability of movement
coupled with the extreme simplicity of construction, the mechanical
hands of this invention can be used for a rich variety of
purposes.
* * * * *