U.S. patent application number 09/828988 was filed with the patent office on 2001-10-11 for pressure-distribution sensor for cotrolling multi-jointed nursing robot.
This patent application is currently assigned to NATIONAL AEROSPACE LABORATORY OF JAPAN. Invention is credited to Izaki, Mitsuharu, Kaminura, Heihachiro, Nagano, Hiroaki, Nakaya, Teruomi, Okamoto, Osamu, Renbutsu, Katsuhiko, Suzuki, Seizo, Ueno, Jyunichi, Usui, Yasuoki, Yabuuchi, Kazuyoshi, Yamaguchi, Isao.
Application Number | 20010029406 09/828988 |
Document ID | / |
Family ID | 18621204 |
Filed Date | 2001-10-11 |
United States Patent
Application |
20010029406 |
Kind Code |
A1 |
Okamoto, Osamu ; et
al. |
October 11, 2001 |
Pressure-distribution sensor for cotrolling multi-jointed nursing
robot
Abstract
The present invention provides contact sensors capable of
determining the pressure distribution over the whole surface of
each of joint units having a cylindrical shape, both end portions
of which are cut at an offset angle, and constituting robot arms.
In order to provide a technology enabling real-time drive control
of the robot arms by using detected values from these sensors, the
points of intersection of the electrodes are distributed across the
whole surface of each joint by forming a pressure-sensitive sheet
sensor in which column electrodes arranged in parallel, and row
electrodes arranged in a wound-string shape, are combined, these
joints having a cylindrical shape, both end portions of which are
cut at an offset angle. In addition, by making an electrode
structure that covers a prescribed width in both rows and columns,
the number of signal output terminals is reduced and the operation
processing load is lightened. Moreover, after executing local
processing, through the use of an encoder and pressure-sensitive
sheet sensor provided in each of the joints, in addition to the
information processing means, [this data] is sent to the CPU,
whereby the central operation processing load is lightened.
Inventors: |
Okamoto, Osamu; (Tokyo,
JP) ; Nakaya, Teruomi; (Tokyo, JP) ; Kaminura,
Heihachiro; (Tokyo, JP) ; Yamaguchi, Isao;
(Tokorozawa-shi, JP) ; Suzuki, Seizo; (Tokyo,
JP) ; Yabuuchi, Kazuyoshi; (Amagasaki-shi, JP)
; Ueno, Jyunichi; (Sanda-shi, JP) ; Usui,
Yasuoki; (Sanda-shi, JP) ; Nagano, Hiroaki;
(Itami-shi, JP) ; Renbutsu, Katsuhiko;
(Takarazuka-shi, JP) ; Izaki, Mitsuharu;
(Kawanishi-shi, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
NATIONAL AEROSPACE LABORATORY OF
JAPAN,
Tokyo
JP
|
Family ID: |
18621204 |
Appl. No.: |
09/828988 |
Filed: |
April 10, 2001 |
Current U.S.
Class: |
700/258 |
Current CPC
Class: |
G01L 5/228 20130101;
B25J 9/06 20130101; G01L 1/205 20130101; B25J 9/0003 20130101; B25J
13/084 20130101; A61G 12/00 20130101 |
Class at
Publication: |
700/258 |
International
Class: |
G05B 019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2000 |
JP |
2000-108346 |
Claims
What is claimed is:
1. A pressure-distribution sensor for controlling a multi-jointed
nursing robot, wherein a pressure-sensitive sheet sensor, in which
column electrodes arranged in parallel on a sheet of substrate
material and row electrodes arranged in a wound-string shape also
on a sheet of substrate material are overlapped, with
pressure-sensitive resistive raw material interposed there between,
the pressure-sensitive sheet sensor being wound around the outer
surface of an arm constituted by multiple joints in which a
plurality of joint units having a cylindrical shape both end
portions of which are cut at an inclined angle are serially
connected, and wherein the points of intersection of both said
[sets of] electrodes are distributed over the whole of the outer
surface area of said joint units, whereby it is possible to detect
pressure distribution.
2. The pressure-distribution sensor for controlling a multi-jointed
nursing robot according to claim 1, wherein, by short-circuiting a
plurality of adjacent column electrodes in addition to
short-circuiting a plurality of adjacent row electrodes, the number
of signal output terminals is reduced and, in addition to the
information processing operation load being lightened, detection of
signals representing areas with a high degree of reliability is
performed.
3. The pressure-distribution sensor for controlling a multi-jointed
nursing robot according to claim 1, wherein, by combining column
electrodes configured in a zigzag shape across a prescribed width
with row electrodes also configured in a zigzag shape across a
prescribed width, the number of signal output terminals is reduced
and, in addition to the information processing load being
lightened, detection of signals representing areas with a high
degree of reliability is performed.
4. A multi-jointed nursing robot control system, wherein, in
addition to each joint unit comprising a pressure-sensitive sheet
sensor, an encoder and information processing means, each joint
unit and the central control CPU are connected to a network, and
local operation processing is executed for each of the joint units
by said information-processing circuit, using the signals output
from said encoder and pressure-sensitive sheet sensor as well as
from the shoulder-side joint position information, this [data]
being sent to the central CPU as reference coordinate system
position information, whereby quick-response processing is
performed.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a robot to assist with the
nursing of the elderly and so on, and more particularly to a
sensor, and peripheral technology thereof, for detecting the
pressure distribution, such as that in multi-jointed arms, and for
use in the drive-control of the robot.
[0003] 2. Description of the Related Art
[0004] In an aging society, while nursing of the elderly and so
forth is of increasing importance, it is physically demanding for
those undertaking the nursing and there are frequent cases of the
caregivers themselves sustaining injuries to hips, knees,
shoulders, arms and so forth. Such situations have given rise to
intensive research and development of means to help with nursing.
The advent of nursing robots is also eagerly anticipated but has
not yet reached the practical stage. Unlike industrial robots,
since such robots are intended for human beings and the physically
weak, the movements of such robots must not only be sufficiently
safe and reliable, but also delicate, so as to provide those
receiving care with a sense of security. In other words, since
people require gentle care, the provision of a nursing robot poses
tremendous difficulties in terms of the control and the mechanics
involved.
[0005] The present inventors initially researched and developed a
"Rotary articulated robot and method of control thereof", this
robot having a construction in which offset joints and rotating
joints were integrated, and a Japanese Patent Application was filed
(H 11-319334). (U.S.P. Ser. No. 09/708,667) In a multi-jointed
robot having a plurality of offset-rotation joints by which the
drive-side arm and driven-side arm are rotatably driven about an
offset-rotation axis inclined with respect to the arm axis, the
multi-jointed robot of this invention is characterized by allowing
a hollow rotating shaft to rotate freely, this hollow rotating
shaft being inclined by a prescribed offset angle and driven by a
motor in the tip of either the drive-side arm or driven-side arm,
and characterized by a rotor member being fixed that transmits a
rotation force from the abovementioned hollow shaft to the base end
of the other arm, and by the abovementioned hollow rotating shaft
and abovementioned rotor member constituting a mechanism permitting
high deceleration ratio transmission and an increase in torque.
With this construction, even smaller drive motors are employed,
greater rotational torque can be transmitted, highly precise
positioning is possible, and a very lightweight joint with offset
rotation at a higher torque is obtained. By virtue of the fact that
this offset-rotation joint is linked at many points, it was
possible to provide a highly functional multi-jointed robot capable
of a wide range of complicated and precise movements with a high
payload.
[0006] The basic construction of an offset-rotation joint in this
multi-jointed robot is shown in FIG. 7. This figure shows the case
where the cylindrical hand-base arm is the drive-side arm 6 and the
hand-end arm is the driven-side arm 7, and depicts a state in which
the driven-side arm 7 is linked by an offset-rotation joint offset
by an offset angle .gamma. with respect to the arm axis of
drive-side arm 6. The tip of the arm min body 6a of drive-side arm
6 is an aperture that is at a right angle to the axis, the base end
of the driven-side arm is an aperture that is inclined at an angle
of inclination .gamma. with respect to the arm axis, and an
offset-rotation joint assembly body is created in the
right-rotation joint assembly body in this embodiment is
constructed by integrating a motor unit 8, a drive-side arm tip
portion 6b fixed to the leading edge of this motor unit, and a
joint rotation transmission mechanism 9 fixed to this drive-side
arm tip portion. A right-angle aperture is created in the base end
side of the drive-side arm tip portion 6b and an inclined aperture
is created in the tip side thereof. The right-angle aperture
receives the tip of the motor shaft, and the joint rotation
transmission mechanism 9 is fixed to the inclined aperture. The
motor unit 8 has a motor case 10 of the same diameter as the arm,
and by integrating the top and bottom ends of this motor case, as
shown in the figure, by linking these ends to the drive-side arm 6a
and drive-side arm tip portion 6b, the motor case 10 itself
comprises one part of the drive-side arm. The motor unit 8
comprises a motor 11 formed so as to be integral with the
abovementioned motor case 10, an encoder E, slip ring 13, and
rotation speedometer (not illustrated), and the motor shaft 14 is
established in a position on the same axis as the arm axis or on a
parallel axis. In a construction of this kind, when the motor 11 is
in a driving condition, the cylinder shaft 21 rotates at a
prescribed rotational speed via the external teeth bevel gear 17
and internal teeth bevel gear 24. Here, by making the diameter of
the internal teeth bevel gear 24 large, [the motor] is able to
decelerate according to the ratio of the [gear] diameters, and a
large torque can be produced using very small motors. Furthermore,
it is possible to obtain a large deceleration ratio with a harmonic
gear mechanism inside joint rotation transmission mechanism 9, and
obtain greater rotational torque using small motors. It is
possible, through this rotational torque, to extend the driven-side
arm 7 through a desired angle with respect to drive-side arm 6.
[0007] The present inventors considered applying the invention
"Rotary articulated robot and method of control thereof",
permitting the provision of a highly functional multi-jointed robot
capable of a wide range of complicated and precise movements with a
high payload, to the arms of a nursing robot, which pose tremendous
difficulties in terms of the control and the mechanics involved
because people require gentle care. As far as the arms of the
nursing robot are concerned, not only is it essential that the arms
be capable of handling the work easily, but the movements of these
arms must also not cause a person in care any pain or discomfort.
For example, if a movement is considered in which a person lying in
bed is picked up [by the robot], when particular locations of the
robot's arms are subjected to concentrations of stress, these arms
touch the person in care strongly in those locations, and the
direct result is that the person is bruised by this strong use of
force. Consequently, it is necessary for the arms of the nursing
robot to deform and make movements to change to a state in which
the person's body is supported uniformly, and for local
concentrations of stress to be avoided. In other words, since it is
required for the nursing robot to make movements according to an
initial objective, while taking appropriate measures to the state
of contact with the person in care, that changes from one moment to
the next, it is necessary for the nursing robot to constantly
detect the state of holding the person in care and perform control
corresponding to this detected value. When attempting to employ the
developed multi-jointed robot, developed by the present applicants,
as a nursing robot, a sensor, for detecting the state of contact
between the robot and the person in care, is of prime
importance.
[0008] Conventionally, pressure-sensitive sheet sensors have been
employed as means for detecting pressure distribution received in
particular areas. Such a sensor is shown in FIG. 6 and is formed as
a layered single sheet comprising column electrodes 2 arranged on a
column electrode side substrate material sheet 1 composed of
polyester film or the like, and row electrodes 4 arranged on a row
electrode side substrate material sheet 5, a pressure-sensitive
resistive raw material 3 being interposed there between. A
pressure-sensitive resistive raw material 3 is interposed between
specific row electrodes and specific column electrodes of this
pressure-sensitive sheet sensor. Consequently, the resistance value
between both [sets of] electrodes depends on the properties of the
pressure-sensitive resistive raw material 3 and shows a value in
accordance with the stress imparted to areas where both [sets of]
electrodes intersect. Therefore, if resistance values between each
row electrode and each column electrode are determined in order, it
is possible to detect the pressure in each location of
intersection. This pressure-sensitive sheet sensor is capable of
detecting the magnitude of the pressure on specific areas that are
covered and position information, in other words the pressure
distribution received. This pressure-sensitive sheet sensor is
employed in the detection of many kinds of pressure distribution
such as the determination of the pressure distribution of a body in
a bed, the pressure distribution on the surface of a vehicle seat,
on a chair seat, on the sole of a foot, and so forth.
[0009] The present inventors employed this pressure-sensitive sheet
sensor in a multi-jointed robot and tried testing [this sensor] as
a sensor for detecting the state of contact of the nursing robot.
However, since the shape adopted for each joint unit of the
multi-jointed robot is not that of a simple cylinder, both end
portions of which being cut at an offset angle, it is not possible
to detect pressure over the whole surface using a conventional
square sheet of matrix electrodes. Further, a nursing robot
necessitates real-time, situation-dependant drive control. However,
it takes a considerably long time to obtain pressure distribution
through operation processing using detected values in a number of
locations of intersection between column electrodes and row
electrodes, and to perform suitable drive control of each joint
based on the contact information [resulting from this processing].
Consequently, the problem of being unable to achieve the required
real-time drive control has become a pressing one.
SUMMARY OF THE INVENTION
[0010] An object of the present invention is to solve [each of] the
abovementioned problems, in other words the task faced by the
present invention is thus to solve the abovementioned problems,
that is, to provide a contact sensor capable of determining the
pressure distribution over the whole surface of each joint unit,
these joint units having a cylindrical shape, both end portions of
which are cut at an offset angle, and constituting robot arms, and
to provide a technology enabling real-time drive control of the
robot arms by using detected values from these sensors.
[0011] Therefore, according to the present invention, since the
points of intersection of the electrodes are distributed over the
whole surface of each joint unit by forming a pressure-sensitive
sheet sensor in which column electrodes arranged in parallel and
row electrodes arranged in a shape resembling that of wound string
[hereinafter referred to as "a wound-string shape"] are combined,
these joints having a cylindrical shape, both end portions of which
are formed as an aperture that is inclined at a prescribed angle
and, in addition, since both the column and row electrodes are
arranged so as to cover the prescribed width, the number of signal
output terminals is reduced and the operation processing load is
lightened. Moreover, after executing local processing of signals
output from sensors in each of the joints through the use of a
processing circuit provided in each of the joints, and sending this
data to the central CPU, the total processing speed is raised.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a diagram showing an image of the nursing robot of
the present invention at work, A showing the subject being held in
a sideways position, and B showing the subject being held in a
forwards position in the lap [of the robot].
[0013] FIG. 2 is a diagram showing the multiple joint mechanism of
the present invention. A shows an overview of the way in which the
multiple joints are interconnected and of the basic construction
each of the joint units has. B is a cross-sectional view of a
joint, and C is a perspective view showing the outer shell with one
part cut away.
[0014] FIG. 3 is a diagram showing the network formed by each joint
unit and the robot's central control CPU. A and B are examples
given for reference, and C is [the network] of the invention.
[0015] FIG. 4 is a diagram showing one embodiment of the
pressure-sensitive matrix sheet sensor of the present invention. A
is a plan view thereof, B is an exploded, cross-sectional view and
C is a cross-sectional view showing the pressure-sensitive matrix
sheet sensor as it is manufactured.
[0016] FIG. 5 is a diagram showing another embodiment of the
pressure-sensitive matrix sheet sensor of the present invention. A
is a plan view thereof and B is a diagram showing the electrode
structure.
[0017] FIG. 6 is a diagram of the structure of a pressure-sensitive
matrix sheet sensor that is typically used. A is a divided,
perspective view thereof, and B is a divided, cross-sectional view
thereof.
[0018] FIG. 7 is a diagram showing the structure of the offset
rotating joints employed in the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] The present invention will now be explained by reference to
the drawings attached.
[0020] The nursing robot is as shown in FIG. 1, specifically, a
push car is provided to substitute the person's feet, and
multi-jointed robot arms are employed, in both of which seven or
eight joints are connected. A pair of multi-jointed arms, a seat,
and the chest and stomach of the robot are used to carry a person
in care, and various carrying conditions are assumed, for example
in which the person in care is held in a sideways position as
depicted in FIG. 1A, in the robot's lap facing forwards as depicted
in FIG. 1B, or further, moved from this position by reclining and
laid down. It is essential that a nursing robot handle a person
gently, and drive control is required that is in keeping with the
person's physical condition and whereby contact is not between both
[robot] arms performing a variety of actions and the affected
region of the person's body. The present inventors attempted to
employ a pressure-sensitive matrix sheet sensor that is normally
used as means for detecting pressure distribution, in the
multi-jointed robot, as a sensor for detecting the contact state of
the nursing robot. However, since the shape of the joint units of
the multi-jointed robot is not that of a simple cylinder, both end
portions thereof being shaped as an aperture that is inclined at a
prescribed angle, it was not possible to detect the pressure
distribution over the whole surface by means of a square matrix
sheet sensor. Because the abovementioned cylindrical joint unit is
in a wound-string shape, if the longest part of the tubular section
is cut in the axial direction and extended by pushing, the present
inventors sought to form the sheet sensor itself in a wound-string
shape, to obtain a pressure-sensitive sheet sensor, in which the
points of intersection of both [sets of] electrodes within the area
of this wound-string shape are distributed uniformly, and to
arrange the column electrodes in parallel and the row electrodes
symmetrically with respect to the center constituted by central
linear electrodes, such that, moving towards the outside, a
wound-string shape results, which gradually becomes deeply concave
at the central portion thereof.
[0021] Further, when conducting an experiment with the row
electrodes of a conventional pressure-sensitive matrix sheet sensor
modified so as to assume a wound-string shape, a nursing robot
necessitates real-time, situation-dependant drive control. However,
it takes a considerably long time to obtain pressure distribution
through operation processing using values detected in a number of
locations of intersection between column electrodes and row
electrodes, and to perform suitable drive control of each joint
based on contact information [resulting from this processing]. The
problem of being unable to achieve the required real-time drive
control has therefore become a pressing one. In fact, since this
contact information is essential for the drive control of each
joint at an appropriate offset angle, finely graded pressure
distribution in the surface of the joint units is not absolutely
necessary. Accordingly, consideration has been given to the fact
that sampling of a predetermined number of the numerous column
electrodes leads to a reduction in the volume of information.
However, here, although the responsiveness was good, there was
concern over the reliability of the pressure information, that is
dependent on the detection signals from parts where electrodes
intersect. Accordingly, the present inventors considered obtaining
information on these areas from output signals from not one point
of intersection but from a number of points of intersection in
neighbouring areas. That does not constitute operation processing
of signals from a number of points of intersection, but is a method
of short-circuiting neighbouring electrodes and forming electrode
groups, without this resulting in discarding signals from unsampled
electrodes. With this construction, suppose that n column
electrodes and m row electrodes are short-circuited, since the
resistance values between these electrodes are constituted by
resistances, of parts where n.times.m electrodes intersect, being
connected in parallel, [these resistances] are present in
resistance values in parts where n.times.m electrodes, in specific
areas, intersect. The reliability of the information becomes high.
Naturally, since this does not involve individually detecting the
resistance values in the parts where n.times.m electrodes
intersect, the operation processing load is the same as that in the
previously mentioned case in which sampling is performed. This
invention determines pressure distribution in particular areas, and
although the position resolving power is imprecise up to the
required level, the detection information is highly reliable in
representing these areas. Hence, the technological significance of
the invention lies in combining a high degree of reliability of
information supplied and a quick response. Moreover, the method
used may be a method involving a construction fulfilling the
abovementioned requirements where, rather than forming the
electrodes into a group, one wide electrode occupies the width of
the group, and the whole of the area is detected as a signal
representing the pressure, without a number of points of
intersection being connected in parallel. However, ideally, it is
preferable for the electrodes used to be linear and not wide, from
the viewpoint of flexibility, since these pressure-sensitive sheet
sensors are to be used for winding around cylindrical joints.
[0022] A multi-jointed mechanism for constructing a pair of arms
for the nursing robot is shown in FIG. 2 and explained in detail
here inbelow. FIG. 2A in the figure is an overview of the way in
which the multiple joints are interconnected and a system for
detecting contact information provided by each joint unit, for
processing signals, and sending and receiving signals. [The end] on
the left of the figure leads to the shoulder portion and [the end]
on the right leads to the tip of the hand. The joint is made from a
lightweight, hard raw material such as aluminum, and the angle of
inclination is, for example, 45 degrees, or possibly 35 degrees.
The shoulder in the main body of the robot is taken as the base
portion and, using a fixed coordinate system, the positional
relationship between each joint is acquired and managed. A network
is formed from each of the joints, and a drive system with a servo
motor at the center thereof is comprised in each joint. In
addition, measuring means, in the form of a rotation speedometer,
encoder, and the abovementioned pressure-sensitive sheet sensor for
obtaining contact information, for example, are comprised.
Information processing means such as a joint database, and a CD ROM
and CPU for the operation thereof, are also provided, in addition
to communication means for managing the network for information
between the joints. FIG. 2A schematically shows only the
pressure-sensitive sheet sensor P, encoder E, information
processing means I and the signal lines L of the communication
means, the drive system being omitted. Since the pressure
distribution information obtained by pressure-sensitive sheet
sensor P is equivalent to the information on the contact between
the robot arms and the person in care, the relative position
information in each joint is insufficient as-is, and, in operating
the robot, the absolute position information from the perspective
of the main body of the robot becomes necessary. In other words,
because the pressure distribution information obtained in each
joint is relative position information in each joint, position
information must be acquired for the whole area of the pair of arms
by converting this information in the fixed coordinate system that
is based on the main body of the robot. In fact, an encoder E is
provided in each joint, and, in addition to detecting the state in
which the driven-side arm 7 in FIG. 7 is connected by an
offset-rotation joint offset by an offset angle .gamma. with
respect to the arm axis of drive-side arm 6, this information is
communicated to adjacent joints, by signal lines passed through a
slip ring 13, and a fixed coordinate system constituting the
standard is configured such that this information is transmitted in
sequence from the shoulder portion side joint. In other words, if
an offset angle .gamma. is supplied from the original information
of the joint encoder, with respect to the fixed coordinate system
of the main body of the robot, since the joint length information
and tip portion inclination angle are already known, the position
information, with respect to the fixed coordinate system, of this
joint can be converted and ascertained. Based on the fixed
coordinate system positional in a similar way using encoder
information in this joint. By performing this coordinate conversion
in each joint, in sequence, in the direction of the fingers,
coordinate conversion is possible for all the joints. Consequently,
although pressure distribution information obtained with
pressure-sensitive matrix sheet sensors in individual joints is
relative position information, if detection information from all of
the joints is combined, it is possible to convert [this
information] to the position information of the standard fixed
coordinate system, in other words to absolute position
information.
[0023] The central computer and network thereof for controlling
each joint and the robot are shown schematically in FIG. 3. In the
figure, Ei indicates the i.sup.th joint encoder, Pi the i.sup.th
joint pressure-sensitive sheet sensor, and the full width
characters "CPU" is the central computer, the half-width characters
"CPU i" indicate the i.sup.th joint. As shown in FIG. 3A, upon
collecting all the detection data from each joint in the CPU of the
central computer and processing the abovementioned coordinate
conversion, the CPU is overloaded and problems arise, namely that
the required real-time processing becomes difficult. Then, as shown
in FIG. 3B, a system was considered that separately provides a
CPU-E dedicated to processing information from the encoder in the
central computer, and a CPU-P dedicated to processing
pressure-distribution information from the sheet sensor. Compared
with the former method of collecting all the data in the CPU of the
central computer and processing [this data], the processing speed
was moderately improved, yet not satisfactory.
[0024] Accordingly, in the present invention, a network system was
considered, as shown in FIG. 3C, in which local processing in each
of the joints is performed and the load in the central CPU is
lightened. In other words, each joint comprises an encoder, and
since joint length information and the tip portion inclination
angle are already known, if this information is supplied with
position information in the shoulder side joint, the position
information for this joint can be locally processed, with the fixed
coordinate system, in the same way as the shoulder side joint. In
the light of this fact, if this processing is performed and the
position information in the standard coordinate system is sent in
sequence from the joint closest to the shoulder-side joint to the
finger-side joint, it is possible for the position information in
the standard coordinate system in this joint to be processed
locally in all the joints. If the position information in the joint
itself is known, it is possible to process and convert, in the
standard coordinate system, the pressure distribution information
obtained from the pressure-sensitive sheet sensor. This means that
encoder information Ei and adjacent shoulder-side joint position
information is input to the CPU i in each joint, and processing and
conversion of the pressure distribution information in these joints
to standard coordinate system information is performed. In this
way, through the use of a construction that completes local
processing, in each joint, of the operation for converting the
pressure distribution information of a specific coordinate system
obtained in each joint to a standard fixed coordinate system, the
present invention lightens the load of the central computer, and
the technological significance thereof lies in the fact that
required real-time drive control is made possible.
[0025] In FIG. 2B is a cross-sectional view (cross-section though
b-b of FIG. 2C) of a joint unit, and FIG. 2C is a perspective view
of one part of the multi-jointed [arm] with the central joint unit
cushioning outer shell cut away. As shown in FIGS. 2B and 2C, a
pressure-sensitive matrix sheet sensor P is wound so as to cover
the outer surface of the joint unit made from a material that is
hard, such as metal. The signal output terminal T of the
abovementioned sheet sensor P is inserted in and connected to
connector C provided in the axial direction of the longest part of
the joint tubular section. Although not shown, this connector C is
connected via a switching circuit to information processing means I
in the form of an IC mounted within the joint. Furthermore, these
information processing means I are connected to signal lines by
which signals are to be sent and received. Also, in order to
produce a gentle feel, the cushioning outer shell H, coming into
direct contact with the person in care, is molded from a material
that is soft and a poor thermal conductor, such as polyurethane
foam.
[0026] Embodiment 1
[0027] FIG. 4 shows one embodiment of the pressure-sensitive matrix
sheet sensor 1 of the present invention. FIG. 4A is a plan view
thereof, FIG. 4B is a divided, cross-sectional view and FIG. 4C is
a cross-sectional view. In this embodiment, an electrically
conductive material such as copper is printed such that a
multiplicity of linear column electrodes 2 are arranged in parallel
on a column electrode side substrate material sheet 1 that is
composed of polyester film, and such that a plurality of adjacent
column electrodes 2 are connected in series. Furthermore, an
electrically conductive material is printed such that a
multiplicity of linear row electrodes 4 are arranged on a row
electrode side substrate material sheet 5 composed of polyester
film, symmetrically with respect to the center constituted by
central linear electrodes, such that, moving towards the outside, a
wound-string shape results, which gradually becomes deeply concave
at the central portion thereof. A plurality of adjacent row
electrodes 4 are thus also connected in series. A special ink in
which a metal powder is contained in a rubbery substance is applied
and printed over the surfaces of both electrode substrate material
sheets 1 and 5 printed with electrodes 2 and 4, and a
pressure-sensitive resistive raw material 3 (a highly sensitive,
electrically conductive elastomer) is stacked thereon. A
pressure-sensitive matrix sheet sensor with a wound-string shape is
manufactured by both sides of pressure resistant material of the
electrode substrate material sheets being overlapped such that they
join together. In this embodiment, by arranging ten of each of the
column electrodes and row electrodes and serially connecting two
adjacent electrodes, the whole area of the sheet is divided into
5.times.5 areas and the pressure distribution is obtained. Signal
output terminals T are established so as to protrude from the
sheet, and upon mounting [the sheet] onto the joint, this part is
bent and inserted in connector C. For the joint control
information, 5.times.5 is considered appropriate, however, [the
division of the sheet] is by no means limited to this number.
Moreover, if the number of electrodes is increased in accordance
with the size of the joint, the number of electrodes to be
connected may then be increased. In specific terms, since printing
technology is used in the manufacture, it is possible for the
configuration of electrodes on the substrate material sheet to be
made with any equivalent design.
[0028] Embodiment 2
[0029] Limiting the volume of information to what is required, the
present inventors proposed a structure in which column electrodes
and row electrodes were configured in a zigzag shape across a
prescribed width, as shown in FIG. 5, as means for obtaining
information with a high degree of reliability. However, in the
actual pressure-sensitive sheet sensor, row electrodes are arranged
in a wound-string shape, however, for the sake of simplicity, FIG.
5A shows these row electrodes in a parallel arrangement. The
special feature of this embodiment lies in the formation of the
electrodes, as made explicit in FIG. 5B, whereby it is possible to
cover an area of a prescribed width by a single electrode without
connecting a plurality of electrodes. This embodiment also has a
resolving power of 5.times.5 for the position information, and the
resistances values, between specific column electrodes and specific
row electrodes adopt a serially connected form in the 5.times.5
parts where [electrodes] intersect. The relationship is such that,
if the width of the zigzag formed by the electrodes is made small,
the number of electrodes becomes large, and the position resolving
power grows large. If the pitch of the zigzag formed by the
electrodes is made small, the number of points of intersection
within specific areas becomes large, and a high degree of
reliability of the signal for the detected pressure received
results. The manufacture of this pressure-sensitive sheet sensor
only differs in the electrode formation, and is not especially
different from the previous embodiment.
[0030] The present invention employs a pressure-sensitive sheet
sensor, in which column electrodes arranged in parallel on a sheet
of substrate material, as well as row electrodes arranged, in a
wound-string shape, on a sheet of substrate material, are
overlapped, with pressure-sensitive resistive raw material
interposed there between, the whole structure also being in a
wound-string shape. Since this pressure-sensitive sheet sensor is
wound around the outer surface of an arm constituted by multiple
joints in which a plurality of joint units are serially connected
and have a cylindrical shape, both end portions of which are cut at
an inclined angle, the points of intersection of both
abovementioned [sets of] electrodes are distributed over the whole
of the outer surface area of abovementioned joint units. The
present invention is thus capable of dead-zone free
pressure-distribution detection in the form of a
pressure-distribution sensor for controlling a multi-jointed
nursing robot.
[0031] Further, by making a pressure-sensitive matrix sheet sensor
in which an electrode structure is adopted, in both the column
direction and the row direction, capable of covering a prescribed
width, the present invention made it possible to reduce the number
of signal output terminals and lighten the information processing
load, and, in addition, to make detection signals capable of
representing these areas with a high degree of reliability, thus
making it possible to combine a high degree of reliability of
information supplied and a quick response.
[0032] Furthermore, in addition to each joint unit of the present
invention comprising an encoder, pressure-sensitive sheet sensor
and information processing means, each joint unit and the central
control CPU were connected to a network, local operation processing
was executed, in each of the joint units, by the use of the
abovementioned information processing circuit, using the signals,
output from the encoder and abovementioned pressure-sensitive sheet
sensor, as well as using the shoulder side joint position
information, and since [this data] was sent to the central CPU as
standard coordinate system position information, it was possible to
lighten the central [CPU] load and perform quick-response control
in the form of a control system for the main body of the
multi-jointed nursing robot.
* * * * *