peT
`WORLD INTELLECfUAL PROPERTY ORGANIZA nON
`International Bureau
`INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`WO 96123478
`
`(11) International Publication Number:
`
`(51) International Patent Classification 6 :
`A61G 5/04, 5106, 862K 17100,8608
`19100
`
`Al
`
`(43) International Publication Date:
`
`8 August 1996 (08.08.96)
`
`(21) International Application Number:
`
`PCfIUS95/01522
`
`(22) International Filing Date:
`
`3 February 1995 (03.02.95)
`
`(81) Designated States: AU, CA, CN, FI, JP, KR, MX, NO, NZ,
`RU, European patent (AT, BE, CH, DE, DK, ES, FR, GB,
`GR, IE, IT, LU, MC, NL, PT, SE).
`
`(71) Applicant: DEKA PRODUCfS LIMITED PARTNERSHIP Published
`[US/US]; 340 Commercial Street, Manchester, NH 03101
`With international search report.
`(US).
`
`(72) Inventors: KAMEN, Dean, L.; 44 Gage Road, Bedford,
`NH 03102 (US). AMBROGI, Robert, R.; 156 Sagamore
`Street, Manchester, NH 03104 (US). DUGGAN, Robert,
`J.; Box 69D RD#2, Old Turnpike Road, Northwood, NH
`03261 (US). HEINZMANN, Richard, Kurt; P.O. Box
`272, Francestown, NH 03043 (US). KEY, Brian, R.; 20
`Windham Road, Pelham, NH 03076 (US). SHOSKIEWICZ,
`Andrzej; 797 Mammoth Road #42, Manchester, NH 03104
`(US). KRISTAL, Phyllis, K.; 121 North Road, Sunapee,
`NH 03782 (US).
`
`(74) Agents: SUNSTEIN, Bruce, D. et at; Bromberg & Sunstein,
`11th floor, 125 Summer Street, Boston, MA 02110-1618
`(US).
`
`(54) Title: TRANSPORTATION VEHICULES AND METHODS
`
`(57) Abstract
`
`There is provided, in a preferred embodiment, a transporta(cid:173)
`tion vehicle for transporting an individual over ground having a
`surface that may be irregular. This embodiment has a support
`for supporting the subjet. A ground-contacting module, movably
`attached to the support, serves to suspend the subject in the sup(cid:173)
`port over the surface. The orientation of the ground-contacting
`module defines fore-aft and lateral planes intersecting one another
`at a vertical. The support and the ground-contacting module are
`components of an assembly. A motorized drive, mounted to the
`assembly and coupled to the ground-contacting module, causes
`locomotion of the assembly and the subject therewith over the
`surface. Finally, the ambodiment has a control loop, in which
`the motorized drive is included, for dynamically enhancing sta(cid:173)
`bility in the fore-aft plane by operation of the motorized drive
`in connection with the ground-contacting module. The ground(cid:173)
`contacting module may be realized as a pair of ground-contacting
`members, laterally disposed with respect to one another. The
`ground-contacting members may be wheels. Alternatively, each
`ground-eontacting member may include a cluster of wheels. In
`another embodiment, each ground-contacting member includes a
`pair of axially adjacent and rotatably mounted arcuate element
`pairs. Related methods are also provided.
`
`Central
`Miaocontroller
`Board
`~i-
`
`Battery
`1------+ Stack
`
`/
`
`:111
`
`Driver
`Inlelface
`AsHmbly
`
`Roll Motor
`Controi
`Aalembly
`
`.n1 .. I
`
`( Right Cluater
`Controf
`Asaembly
`
`').77.. I
`~ Right Wheel
`
`Control
`Asaembiy
`
`Swagway_1004
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`

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`FOR THE PURPOSES OF INFORMATION ONLY
`
`Codes used to identify States party to the per on the front pages of pamphlets publishing international
`applications under the per.
`
`AM
`AT
`AU
`BB
`BE
`BF
`BG
`BJ
`BR
`BY
`CA
`CF
`CG
`CH
`CI
`CM
`CN
`CS
`CZ
`DE
`DK
`EE
`ES
`FI
`FR
`GA
`
`Annenia
`Austtia
`Austtalia
`Barbados
`Belgium
`BurlcinaFuo
`Bulgaria
`Benin
`Brazil
`Belarus
`Canada
`Centtal African Republic
`Congo
`Switzerland
`COte d'lvo~
`Cameroon
`China
`Czechoslovakia
`Czech Republic
`Gennany
`Denmuk
`Estonia
`Spain
`Finland
`France
`Gabon
`
`GB
`GE
`GN
`GR
`HU
`IE
`IT
`JP
`KE
`KG
`KP
`
`KR
`KZ
`LI
`LK
`LR
`LT
`LV
`LV
`MC
`MD
`MG
`ML
`MN
`MR
`
`United Kingdom
`Georgia
`Guinea
`Greece
`Hungary
`Ireland
`Italy
`Japan
`Kenya
`Kyrgystan
`Democratic People' s Republic
`of Korea
`Republic of Korea
`Kazakhstan
`Liecluenstein
`Sri Lanka
`Liberia
`Lithuania
`Luxembourg
`Lalvia
`Monaco
`Republic of Moldova
`Madagascar
`Mali
`Mongolia
`Mauritania
`
`MW
`MX
`NE
`NL
`NO
`NZ
`PL
`PT
`RO
`RU
`SD
`SE
`SG
`SI
`SK
`SN
`SZ
`TO
`TG
`TJ
`TT
`UA
`UG
`US
`UZ
`VN
`
`Malawi
`Mexico
`Niger
`Netherlands
`Norway
`New Zea1and
`Poland
`Portugal
`Romania
`Russian Federation
`Sudan
`Sweden
`Singapo~
`Slovenia
`Slovakia
`Senegal
`Swaziland
`Chad
`Togo
`Tajikistan
`Trinidad and Tobago
`Ukraine
`Uganda
`United States of America
`Uzbekistan
`Viet Nam
`
`Swagway_1004
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`

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`W096/23478
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`PCfIUS95/01522
`
`- 1 -
`
`TRANSPORTATION VEHICLES AND METHODS
`
`5
`
`Technical Field
`
`The present invention pertains to vehicles and methods for transporting
`
`individuals, and more particularly to vehicles and methods for transporting
`
`10
`
`individuals over ground having a surface that may be irregular.
`
`Background Art
`
`A wide range of vehicles and methods are known for transporting human
`
`subjects. The design of these vehicles has generally resulted from a compromise
`
`that favors stability over maneuverability. It becomes difficult, for example, to
`
`15 provide a self-propelled user-guidable vehicle for transporting persons over
`
`grow1d having a surface that may be irregular, while still permitting convenient
`
`locomotion over ground having a surface that is relatively flat. Vehicles that
`
`achieve locomotion over irregular surfaces tend to be complex, heavy, and
`
`difficul t for ordinary locomotion.
`
`20
`
`Summary of the Invention
`
`The invention provides, in a preferred embodiment, a vehicle for
`
`transporting a human subject over ground having a surface that may be
`
`irregular. This embodiment has a support for supporting the subject. A ground(cid:173)
`
`contacting module, movably attached to the support, serves to suspend the
`
`25 subject in the support over the surface. The orientation of the ground-contacting
`
`module defines fore-aft and lateral planes intersecting one another at a vertical.
`
`The support and the ground-contacting module are components of an assembly.
`
`A motorized drive, mounted to the assembly and coupled to the ground(cid:173)
`
`contacting module, causes locomotion of the assembly and the subject therewith
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`Swagway_1004
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`W096/23478
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`PCTlUS95/0 1522
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`- 2-
`
`over the surface. Finally, the embodiment has a control loop, in which the
`
`motorized drive is included, for dynamically enhancing stability in the fore-aft
`
`plane by operation of the motorized drive in cOlUlection with the ground(cid:173)
`
`contacting module.
`In a further embodiment, the ground contacting module is realized as a
`
`5
`
`pair of ground-contacting members, laterally disposed with respect to one
`
`another. The ground-contacting members may be wheels. Alternatively, each
`
`ground-contacting member may include a cluster of wheels, each cluster being
`
`rotatably mounted on and motor-driven about a common laterally disposed
`
`10 central axis; each of the wheels in each cluster may be rotatably mounted about
`
`an axis parallel to the central axis so that the distance from the central axis
`
`through a diameter of each wheel is approximately the same for each of the
`
`wheels in the cluster. The wheels are motor-driven independently of the cluster.
`
`In yet another embodiment, each ground-contacting member includes a
`
`15 pair of axially adjacent and rotatably mounted arcuate element pairs. The arcuate
`
`elements of each element pair are disposed transversely at opposing ends of a
`support strut that is rotatably mounted at its midpoint. Each support strut is
`
`motor-driven.
`
`Brief Description of the Drawings
`
`20
`
`The invention will be more readily understood by reference to the
`
`following description, taken with the accompanying drawings, in which:
`
`Fig. 1 is a perspective view of a simplified embodiment of the present
`
`invention, showing a subject seated thereon;
`
`Fig. 2 another perspective view of the embodiment of Fig. I, showing
`
`25
`
`further details of the embodiment;
`
`Fig. 3 is a schematic view of the embodiment of Fig. I, showing the swivel
`
`arrangement of this embodiment;
`
`Fig. 4 is a side elevation of the embodiment of Fig. 1 as used for climbing
`
`stairs;
`
`30
`
`Fig. 5 is a block diagram showing generally the nature of power and
`
`control with the embodiment of Fig. 1;
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`- 3 -
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`Fig. 6 illustrates the control strategy for a simplified version of Fig. 1 to
`
`achieve balance using wheel torque;
`
`Fig. 7 illustrates diagrammatically the operation of joystick control of the
`
`wheels of the embodiments of Fig. 1;
`
`5
`
`Fig. 8 illustrates the procedures utilized by the embodiment of Fig. 1 to
`
`ascend and descend stairs;
`
`Figs. 9-21 illustrate embodiments of the invention utilizing a pair of wheel
`
`clusters as the ground-contacting members;
`
`Figs. 9-10 show use of a two-wheel cluster design in various positions;
`
`10
`
`Figs. 11-21 show use of a three-wheel cluster design in various positions
`
`and configurations;
`
`Figs. 22-24 illustrate an embodiment wherein each ground-contacting
`
`member is realized as a plurality of axially adjacent and rotatably mounted
`
`arcuate element groups;
`
`15
`
`Figs. 25-26 provide mechanical detail of a three-wheel cluster design for
`
`use in the embodiment of Figs. 18-20;
`
`Fig. 27 is a block diagram showing communication among the control
`
`assemblies used in the embodiment of Figs. 18-20;
`
`Fig. 28 is a block diagram showing the structure of a generic control
`20 assembly of the type used in the embodiment of Fig. 27;
`
`Fig. 29 is a block diagram providing detail of the driver interface assembly
`
`273 of Fig. 27;
`
`Fig. 30 is a logical flow diagram followed by the central micro controller
`
`board 272 of Fig. 27 in the course of one control cycle;
`
`25
`
`Fig. 31 illustrates variables defining the dimensions of the cluster design
`
`of Figs. 11-26 and of a hypothetical stair with respect to which the cluster design
`
`will be used for ascent or descent;
`
`Fig. 32 illustrates angle variables pertinent to defining orientation of the
`
`cluster in relation to the vehicle and to the world;
`
`30
`
`Fig. 33 is a schematic of the wheel motor control during balancing and
`
`normal locomotion;
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`-4-
`
`Fig. 34 is a schematic of the cluster control arrangement during balancing
`
`and normal locomotion;
`
`Fig. 35 is a schematic, relating to Fig. 33, showing the arrangement by
`
`which the state variables indicating wheel position are determined so as to
`
`5 compensate for the effects of cluster rotation;
`
`Figs. 36-38 illustrate the control arrangement for stair-climbing and
`
`obstacle traversal achieved by the cluster design of Figs. 11-26 in accordance with
`
`a first embodiment permitting climbing;
`
`Fig. 36 is a schematic for the control arrangement for the cluster motors in
`
`10
`
`the first embodiment permitting climbing, here employing a lean mode;
`
`Fig. 37 is a schematic for the control arrangement for the wheel motors in
`the first embodiment permitting climbing;
`
`Fig. 38 is a block diagram of the state of the vehicle, utilizing the first
`
`embodiment permitting climbing, for moving among idle,lean, and balance
`
`15 modes;
`
`Figs. 39A-B, 40A-B, 41A-B, and 42A-C illustrate stair-climbing achieved by
`
`the cluster design of Figs. 11-26 in accordance a second embodiment permitting
`
`climbing;
`
`Figs. 39A and 39B illustrate orientation of the cluster in the sequence of
`
`20 starting stair climbing in accordance with the second climbing embodiment;
`
`Figs. 40A and 40B illustrate orientation of the cluster in the sequence of
`resetting the angle origins in this embodiment;
`
`Figs. 41A and 41B illustrate orientation of the cluster in the sequence of
`
`transferring weight in this embodiment;
`
`25
`
`Figs. 42A, 42B, and 42C illustrate orientation of the cluster in the sequence
`
`of climbing in this embodiment;
`
`Fig. 43 is a schematic for the control arrangement for the wheel and cluster
`
`motors during the start sequence of Figs. 39A and 39B;
`
`Fig. 44 is a schematic for the control arrangement for the wheel motors
`
`30 during the weight transfer sequence of Figs. 41A and 41B; and
`
`Fig. 45 is a schematic for the control arrangement during the climb
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`sequence of Figs. 42A, 42B, and 42C.
`
`-5-
`
`Figs. 46 and 47 show schematically a vehicle in accordance with an
`
`embodiment of the present invention equipped with sensors for ascent and
`
`descent of stairs and other similar obstacles.
`
`5
`
`Fig. 48 shows a vertical section of an embodiment of the invention in a
`
`configuration, similar that of Figs.9-12, utilizing harmonic drives.
`
`Fig. 49 shows detail of the cluster portion of the vehicle of Fig. 48.
`
`Fig. 50 shows detail of the cluster drive arrangement of the vehicle of Fig.
`
`48.
`
`10
`
`Fig. 51 shows an end view of a cluster of the vehicle of Fig. 48.
`
`Fig. 52 shows the mechanical details of the hip and knee joints of the
`
`vehicle of Fig. 48.
`
`Fig. 53 illustrates an embodiment of the invention providing non-visual
`
`outputs useful for a subject in control of a vehicle.
`
`15
`
`Detailed Description of Specific Embodiments
`
`The invention may be implemented in a wide range of embodiments. A
`
`characteristic of many of these embodiments is the use of a pair of laterally
`
`disposed ground-contacting members to suspend the subject over the surface
`
`with respect to which the subject is being transported. The ground-contacting
`
`20 members are motor-driven. In many embodiments, the configuration in which
`
`the subject is suspended during locomotion lacks inherent stability at least a
`
`portion of the time with respect to a vertical in the fore-aft plane but is relatively
`stable with respect to a vertical in the lateral plane. Fore-aft stability is achieved
`
`by providing a control loop, in which the motor is included, for operation of the
`
`25 motor in connection with the ground-contacting members. As described below,
`
`the pair of ground-contacting members may, for example, be a pair of wheels or
`
`a pair of wheel clusters. In the case of wheel clusters, each cluster may include a
`
`plurality of wheels. Each ground-contacting member, however, may instead be a
`
`plurality (typically a pair) of axially-adjacent, radially supported and rotatably
`
`30 mounted arcuate elements. In these embodiments, the ground-contacting
`
`members are driven by the motorized drive in the control loop in such a way as
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`- 6 -
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`to maintain the center of mass of the vehicle above the point of contact of the
`
`ground-contacting members with the ground, regardless of disturbances and
`
`forces operative on the vehicle.
`In Fig. 1 is shown a simplified embodiment of the invention in which the
`
`5 principal ground-contacting members are a pair of wheels and in which
`
`supplemental ground-contacting members are used in stair climbing and
`
`descending. (As will be shown below, stair climbing and descent and flat-terrain
`
`locomotion may both be achieved with a single set of ground-contacting
`
`members, when such members are the wheel clusters or the arcuate elements
`
`10
`
`referred to above.)
`
`The embodiment shown in Fig. 1 includes a support arrangement 12,
`
`embodied here as a chair, on which a subject 13 may be seated. The vehicle is
`
`provided with a pair of wheels 11 disposed laterally with respect to one another.
`
`The wheels help to define a series of axes including the vertical axis Z-Z, a lateral
`
`15 axis Y-Y parallel to the axis of the wheels, and a fore-aft axis X-X perpendicular
`
`to the wheel axis. The plane defined by the vertical axis Z-Z and the lateral axis
`
`y-y will sometimes be referred to as the "lateral plane", and the plane defined by
`
`the fore-aft axis X-X and the vertical axis Z-Z will sometimes be referred to as the
`
`"fore-aft plane". Directions parallel to the axes X-X and Y-Y are called the fore-aft
`
`20 and lateral directions respectively. It can be seen that the vehicle, when relying
`
`on the pair of wheels 11 for contacting the ground, is inherently unstable with
`
`respect to a vertical in the fore-aft direction, but is relatively stable with respect
`
`to a vertical in the lateral direction.
`In Fig. 2 it can be seen that in addition to wheels 11, the vehicle is
`
`25 provided with a pair of laterally disposed feet 21 capable of being extended in
`
`the vertical direction by controllable amounts, and a footrest 22. The footrests are
`
`here provided with sensors for determining the height of objects such as stairs
`
`over which they may be disposed. The feet 21 are disposed on a pair of
`
`corresponding extendable legs 23. In a preferred embodiment, the vehicle is
`
`30 stable in the fore-aft direction as well as the lateral direction when both feet are
`
`in contact with the ground, but lateral stability may be sacrificed when one foot
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`is in contact with the ground.
`
`- 7-
`
`In Fig. 3 is shown an arrangement of the embodiment of of Figs. 1 and 2
`
`permitting swivel of the chair 12 with respect to the suspension system,
`
`including feet 21 and related legs 23. The swivel operates in a plane that is
`
`5 approximately horizontal. The swivel arrangement, in combination with the
`
`ability to extend and retract each leg, permits motion of the vehicle up and down
`
`stairs in a manner analogous to human locomotion on stairs. Each leg 23, when
`
`serving as the weight-bearing leg, permits rotation of the remainder of the
`
`vehicle about the leg's vertical axis in the course of a swivel. In achieving the
`
`10 swivel, the chair pivots about a vertical axis disposed centrally between the legs
`
`23 to maintain the chair's forward-facing direction. Additionally, the non-weight(cid:173)
`
`bearing leg 23 is rotated about its vertical axis in the course of a swivel to
`
`maintain its related foot 21 in a forward-facing direction.
`
`It can be seen that the embodiment described in Figs. 1-3 sacrifices
`
`15
`
`inherent fore-aft stability in order to achieve relative mobility. For generally
`
`gradual surface changes, the balance mode involves providing fore-aft stability
`
`to an otherwise inherently unstable system. For more irregular surfaces, such as
`
`stairs, this embodiment has a separate "step mode" used for climbing or
`
`descending stairs. Stability may be regained in climbing or descending stairs, for
`
`20 example, by using a hand to grab an ordinary handrail 41, as shown in Fig. 4, or
`
`even contacting an available wall near the stairs.
`
`In addition, a variety of strategies may be used to reduce the risk of injury
`
`arising from a fall. In one arrangement, in the event that a fall is determined to
`
`be about to occur, the vehicle may enter a squat mode in which it controllably
`
`25 and quickly lowers the center of mass of the combination of vehicle and human
`
`subject. A lowering of the center of mass may be achieved, for example, by
`
`hinging or separating the suspension system in such a manner as to cause the
`
`height of the chair from the surface to be reduced. A squat mode could also have
`
`the beneficial effects of dissipating energy before imparting it to the subject,
`
`30 placing the subject in a position so as to reduce the subject's vulnerability, and
`
`putting the subject in a position that is lower so as to reduce the energy
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`transferred to the person in case of impact.
`
`- 8 -
`
`In the block diagram of Fig. 5 it can be seen that a control system 51 is
`
`used to control the motor drives and actuators of the embodiment of Figs. 1-4 to
`
`achieve locomotion and balance. These include motor drives 531 and 532 for left
`
`5 and right wheels respectively, actuators 541 and 542 for left and right legs
`
`respectively, and swivel motor drive 55. The control system has data inputs
`
`including user interface 561, pitch sensor 562 for sensing fore-aft pitch, wheel
`
`rotation sensors 563, actuator height sensor 564, swivel sensor 565, and stair
`
`dimension sensor 566.
`
`10
`
`A simplified control algorithm for achieving balance in the embodiment of
`
`the invention according to Fig. 1 when the wheels are active for locomotion is
`
`shown in the block diagram of Fig. 6. The plant 61 is equivalent to the equations
`
`of motion of a system with a ground contacting module driven by a single motor,
`before the control loop is applied. T identifies the wheel torque. The character e
`identifies the fore-aft inclination (the pitch angle of the vehicle with respect to
`
`15
`
`gravity, i.e., the vertical), X identifies the fore-aft displacement along the surface
`
`relative to the reference point, and the dot over a character denotes a variable
`
`differentiated with respect to time. The remaining portion of the figure is the
`
`control used to achieve balance. The boxes 62 and 63 indicate differentiation. To
`
`20 achieve dynamic control to insure stability of the system, and to keep the system
`
`in the neighborhood of a reference point on the surface, the wheel torque Tin
`
`this embodiment is set to satisfy the following equation:
`T = KI e + Ki) + K3X + K4x
`
`The gains KI , K 2, K 3, and K4 are dependent upon the physical parameters of the
`25 system and other effects such as gravity. The simplified control algorithm of Fig.
`
`6 maintains balance and also proximity to the reference point on the surface in
`
`the presence of disturbances such as changes to the system's center of mass with
`
`respect to the reference point on the surface due to body motion of the subject or
`
`contact with other persons or objects.
`
`30
`
`In order to accommodate two wheels instead of the one-wheel system
`
`illustrated in Fig. 6, the torque desired from the left motor and the torque desired
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`-9-
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`from the right motor can be calculated separately in the general manner
`
`described below in connection with Fig. 33. Additionally, tracking both the left
`
`wheel motion and the right wheel motion permits adjustments to be made to
`
`prevent unwanted turning of the vehicle and to account for performance
`
`5 variations between the two drive motors.
`
`A manual interface such as a joystick is used to adjust the torques of each
`
`motor. The joystick has axes indicated in Fig. 7. In operation of this embodiment,
`
`forward motions of the joystick is used to cause forward motion of the vehicle,
`
`and reverse motion of the joystick causes backward motion of the vehicle. A left
`
`10
`
`turn similarly is accomplished by leftward motion of the joystick. For a right
`
`turn, the joystick is moved to the right. The configuration used here permits the
`
`vehicle to tum in place when the joystick is moved to the left or to the right. With
`
`respect to forward and reverse motion an alternative to the joystick is simply
`
`leaning forward or backward, since the pitch sensor (measuring 6) would
`
`15
`
`identify a pitch change that the system would try to compensate for, leading to
`
`forward or reverse motion, depending on the direction of lean. Alternatively,
`
`control strategies based on fuzzy logic can be implemented.
`
`It can be seen that the approach of adjusting motor torques when in the
`
`balance mode permits fore-aft stability to be achieved without the necessity of
`
`20 additional stabilizing wheels or struts (although such aids to stability may also
`
`be provided). In other words, stability is achieved dynamically, by motion of the
`
`components of the vehicle (in this case constituting the entire vehicle) relative to
`
`the ground.
`
`Stair-Climbing with Legs
`
`25
`
`Fig. 8 shows one manner of stair climbing and stair descending with the
`
`embodiment of Fig. 1. In confronting a stair, initially both legs are retracted
`
`(shown in block 71), and then the height of the first step is measured (block 72).
`
`A determination is made whether stair ascent or descent is to occur (73). (At this
`
`point, it is helpful, to achieve stability, for the subject to hold an available
`
`30 handrail.)
`Thereafter, in the first stage of stair ascent (shown in block 74), a first leg is
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`-10 -
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`extended until the second leg clears the step (75). The vehicle then swivels until
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`the second leg is over the step it has just cleared (78). (In implementing this stage,
`it is possible to use a sensor to determine how far to swivel based on the step
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`depth. Alternatively, the swivel can be over a specified angle, such as 90
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`5 degrees.) The sensor is then checked to measure the height of the next step (72).
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`If a step is determined to be present (73), and the previous step was odd (76), the
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`process is continued by extending the second leg and retracting the first leg until
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`the first leg clears the next step (79). Next, the vehicle swivels until the first leg is
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`over the cleared step (80). The sensor is then checked to measure the height of
`
`10
`
`the next step (72). If a step is determined to be present (73), and the previous step
`
`was even (76), the process is continued by extending the first leg and retracting
`
`the second leg until the second leg clears the next step (78). The process is
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`repeated beginning at block 72. If no step is detected, if the previous step was
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`odd, it is completed by slightly extending the second leg, fully retracting the first
`
`15
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`leg, swiveling until both legs face forward, and then retracting the second leg to
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`stand on both feet. If no step is detected, if the previous step was even, it is
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`completed by slightly extending the first leg, fully retracting the second leg,
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`swiveling until both legs face forward, and then retracting the first leg to stand
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`on both feet (88).
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`20
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`An analogous procedure is followed for descending stairs. In the first
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`stage of stair descent (shown in block 81), the first leg is slightly extended to
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`clear the second leg (block 82). Thereafter, the vehicle swivels until the second
`leg is over the step onto which it is going to descend (84), the first leg is retracted
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`and the second leg is extended until the second leg is on the step (85). The sensor
`
`25
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`is then checked to measure the height of the next step (72). If a step is determined
`
`to be present (73), and the previous step was odd, the process is continued by
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`swiveling until the first leg is over the step onto which it is going to extend (86).
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`The second leg is then retracted and the first leg extended until the first leg is on
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`the step (block 87). The sensor is then checked to measure the height of the next
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`30 step (72). If a step is determined to be present (73), and the previous step was
`
`even, the process is continued (84), and then repeated beginning at block 72. If no
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`W096/23478
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`PCTIUS95/0 1522
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`- 11 -
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`step is detected, descent is completed by swiveling until both legs face forward,
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`and then retracting both legs to stand on both feet (88).
`
`In lieu of the swivel arrangement discussed above, in a further
`
`embodiment, relative motion of the legs may be achieved by causing each leg to
`
`5 be mounted in a manner as to permit it to slide in an approximately horizontal
`
`plane in the fore and aft directions. Alternatively, the legs may utilize joints
`
`analogous to knee and hip joints of human subjects.
`
`Stair-CIimbing with Clusters
`
`Whereas the embodiment of Fig. 1 requires different ground-contacting
`
`10 members for stair-climbing and for level terrain navigation, the embodiments of
`
`the invention shown in Figs. 9-21 successfully utilize the same set of ground(cid:173)
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`contacting members for both stair-climbing and for level terrain navigation. Figs.
`
`9-18 illustrate embodiments of the invention utilizing a pair of wheel clusters as
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`the ground-contacting members in lieu of the pair of wheels used in the
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`15 embodiment of Fig. 1.
`
`In Fig. 9, there is shown a side view of an embodiment utilizing a two(cid:173)
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`wheel cluster design. The subject 962 is shown supported on the seat 95 of this
`
`embodiment. In view is the right-hand cluster 91 with a pair of wheels 931 and
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`932 in radially symmetric locations about the cluster's axis 92 of rotation. A
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`20 similar left-hand cluster is also employed. Each cluster has its own separately
`
`controlled motor to drive it about its axis of rotation 92. Each pair of wheels
`(here, 931 and 932) is also driven by a separately controlled motor about its own
`
`axis of rotation, but the wheels of a cluster are coupled to rotate synchronously.
`
`It can be seen in Fig. 9 that the cluster 91 is positioned so that both wheels
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`25 931 and 932 may be in contact with the ground. When the cluster 91 (along with
`
`the left-hand cluster) is in this position, the vehicle of this embodiment is
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`relatively stable in the fore-aft plane, thereby permitting a subject 961 shown
`
`standing) to assume rapidly a comfortable seated position 962 on the vehicle or,
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`for example, a handicapped person to transfer from another chair.
`
`30
`
`The cluster 91, however, may be rotated about its axis 92 until only wheel
`
`932 of each cluster is in contact with the ground as shown in Fig. 10. When the
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`W096/23478
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`PCTlUS95/01522
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`- 12-
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`cluster 91 (along with the left-hand cluster) is in this position, the vehicle has the
`
`same inherent fore-aft instability as discussed above in connection with the
`
`embodiment of Fig. 1. The same equations governing the system may be used as
`
`discussed above in order to drive the wheels to create fore-aft stability
`
`5 dynamically. Also as shown in Figs. 9 and 10, the chair 95 may be linked to the
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`ground-contacting members via an articulated arm having segments 941 and 942
`
`that may be adjusted in angle with respect to each other and the seat 95. The
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`adjustments are achieved by motorized drives disposed at hubs 945 and 946.
`
`(Such drives may, for example, be harmonic drives.) As a result of these
`
`10 adjustments (in addition to the effect of rotating the clusters), the height of the
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`seat 95, among other things, may be changed; it can be seen that the subject 101
`
`may achieve a height while seated on the vehicle comparable to (or even greater
`
`than) a standing subject 961. This is desirable, since seated subjects, in wheel
`chairs, for example, are commonly dwarfed by standing subjects. As will be
`
`15 discussed in further detail below, the foregoing adjustments also permit
`
`adjustment of the fore-aft tilt of the seat.
`
`Figs. 11-18 show use of a three-wheel cluster design in various modes and
`
`configurations. Figs. 11 (showing stable rest position) and 12 (showing balancing
`position for travel) for three-wheel clusters correspond to Figs. 9 and 10 for two-
`
`20 wheel clusters. Each three-wheel cluster (right-hand cluster 111 is shown here) is
`
`rotatably mounted and motor-driven about axis 112, using separately
`
`controllable motors. As in the case of the two-wheel cluster design, the wheels of
`
`each cluster are separately driven and controlled, but run synchronously in each
`
`cluster.
`
`25
`
`It should be noted that although many of the embodiments described
`
`herein utilize separate motors individually controlled, a common motor may be
`
`used for a number of functions, and the separate control may be achieved by
`
`appropriate clutch or other power transmission arrangement, such as a
`differential drive. The term "motorized drive" as used in this description and the
`
`30
`
`following claims means any vehicle that produces mechanical power regardless
`
`of means, and therefore includes a motor that is electric, hydraulic, pneumatic, or
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`W096/23478
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`- 13 -
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`thermodynamic (the latter including an internal combustion or an external
`
`combustion engine) together with any appropriate arrangement for transmission
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`of such mechanical power; or a thrust-producing device such as a turbojet engine
`
`or a motor-driven propeller.
`Fig. 13 is similar to Fig. 12, but here the chair 95 is shown having a back
`
`5
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`131 and a seat 132. The angle of back 131 relative to the seat 132 and the angle of
`
`the seat 132 relative to the horizontal may be adjusted so that with the back 131
`
`in a generally vertical orientation, the seat 132 may be tilted toward the vertical
`
`to permit the user to assume a more nearly standing position.
`
`10
`
`In Fig. 14, the embodiment is shown climbing stairs. The articulated arm
`
`segments 941 and 942 are here in the extended position to provide maximum
`
`height, so that the feet of the subject 101 to clear the stairs 141. Stair climbing is
`
`achieved by rotation of each of the right cluster 111 and left cluster (not shown)
`
`about central axis 112 and coordinated rotation of the wheels. The actual modes
`
`15 and control arrangements