Motor vehicles – Special driving device – Stepper
Reexamination Certificate
2001-08-15
2003-06-03
Dickson, Paul N. (Department: 3616)
Motor vehicles
Special driving device
Stepper
C180S007100, C180S006500, C180S021000, C180S065800, C180S907000, C180S280000, C180S009260, C180S193000, C701S124000
Reexamination Certificate
active
06571892
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates to the field of controlling a device. More particularly, the present invention relates to multi-modal control systems and methods for controlling the operation of a transport device.
2. Discussion of the Related Art
Human transport devices serve to move a person over a surface and may take many different forms. For example, a human transport device, as the term is used herein, may include, but is not limited to, wheelchairs, motorized carts, bicycles, motorcycles, cars, hovercrafts, and the like. Some types of human transport may include stabilization mechanisms to help ensure that the device does not fall over and injure the user of the transport device.
A typical four-wheeled wheelchair contacts the ground with all four wheels. If the center of gravity of the combination of the wheelchair and the user remains over the area between the wheels, the wheelchair should not tip over. If the center of gravity is located above and outside of the ground contacting members of the transport device, the transport device may become unstable and tip over.
Referring now to
FIG. 1A
, a typical wheelchair
100
is shown. The wheelchair
100
and the user
102
define a frame. The frame has a center of gravity
104
located at a position vertically disposed above the surface
106
. The term “surface” as it is used herein shall refer to any surface upon which a human transport device may sit. Examples of a surface include flat ground, an inclined plane such as a ramp, a gravel covered street, and may include a curb which vertically connects two substantially parallel surfaces vertically displaced from one another (e.g., a street curb).
The surface
106
may be at an incline as compared to the horizontal axis
108
. The angle by which the surface
106
is offset from the horizontal axis
108
shall be referred to herein as the surface pitch and will be represented by an angle denoted as &thgr;
s
.
The front wheel
112
and the rear wheel
110
of the wheelchair
100
are separated by a distance d. The distance d between the two wheels may be measured as a linear (e.g., straight line) distance. If the center of gravity
104
of the system is located at a position above and between the two wheels,
110
and
112
, the wheelchair
100
should remain upright and relatively stable. The wheels
110
and
112
typically have opposing counterparts (not shown) on the other side of the wheelchair. The opposing counterparts may each share an axis with wheels
110
and
112
, respectively. The area covered by the polygon which connects the points where these four wheels touch the ground (or the outside portions of the ground contacting parts, when the ground contacting part may cover more than a point) provides an area over which the center of gravity
104
may be located while the wheelchair remains stable. In various places in this discussion below this area may be referred to as the footprint of the device. The footprint of a device, as the term is used herein, is defined by the projection of the area between the wheels as projected onto the horizontal plane. If the center of gravity is above this location, the transport device should remain stable.
If the center of gravity
104
is vertically displaced above the surface
106
and outside the footprint (i.e., the projection of area between the wheels
110
and
112
onto the horizontal plane), the stability of the wheelchair
100
may decrease and the wheelchair
100
may tip over. This could happen, for example, when the wheelchair is on a surface that has a steep incline. When on a steep incline, the center of gravity
104
may shift back and cause the wheelchair
100
to flip over backwards. This is shown in
FIG. 1B
where the center of gravity
104
is located at a position that is outside the footprint of the wheelchair
100
. The center of gravity
104
is shown including a gravity acceleration vector (g) which linearly translates the center of gravity
104
in a downward direction. The wheelchair
100
may rotate about an axis of the rear wheel
110
until the wheelchair
100
contacts the surface being traversed.
The user
102
may help to return the center of gravity
104
to a location that is above the area between the wheels
110
and
112
by leaning forward in the wheelchair
100
. Given this limited control of the location of the center of gravity
104
, it is clear that human transport devices such as wheelchairs may encounter great difficulties when traversing uneven surfaces such as a curb or steps.
Other types of human transport devices may include control mechanisms which allow the transport device to balance on two wheels. The two wheels may be connected to a single3 axis that passes through the center of the wheels. The axis connects the wheels in such a manner that the forward and backwards motion of the device is perpendicular to the axis. The control mechanisms may keep the device and the user in a stable upright position by driving the wheels forwards and backwards to keep the center of gravity located over the wheel axis. Such devices may additionally provide for locomotion by allowing the center of gravity to be displaced by a distance forward or backwards from wheel axis and having the wheels rotate in order keep the center of gravity located at that position. Examples of such devices are disclosed in U.S. Pat. Nos. 5,701,965 and 5,719,425 which are hereby incorporated by reference.
SUMMARY OF THE INVENTION
According to one embodiment of the present invention, a self balancing human transport device is disclosed. According to this embodiment, the transport device includes a movable arm and a ground contacting member coupled to the moveable arm. The transport device also includes a control unit to control movement of the arm in order to balance the transport device and to control movement of the ground contacting member in order to balance the transport device.
According to another embodiment of the present invention, a method of controlling a human transport device is disclosed. According to this embodiment, the method includes a step a) of moving an arm in order to balance the transport device. The method also includes a step b) of during step a) moving a ground contacting member in order to balance the transport device.
According to another embodiment of the present invention a human transport device capable of operating in a plurality of operational modes is disclosed. In this embodiment the transport device includes a rotatable cluster that has at least one ground contacting member and at least one actuator to move the cluster and the ground contacting member. In this embodiment the transport device also includes a control unit that provides a control signal to the actuator, the control unit providing the control signal such that the actuator causes both the cluster to rotate and the ground contacting member to move such that a center of gravity of the human transport device is located at a position vertically displaced between endpoints of the cluster.
According to another aspect of the present invention a transport device is disclosed. According to this embodiment, the transport device includes a control unit that provides control signals to the transport device such that a center of gravity of a system which includes the transport device and a user is displaced above a center of a footprint of the device, the footprint having a non-zero area.
In another embodiment of the present invention a method of controlling a transport device having a human occupant, the transport device having a cluster with wheels attached thereto and having a footprint whose area is greater than about zero is disclosed. In this embodiment the transport device is controlled by simultaneously controlling a position of the cluster and a position of the wheels such that a center of gravity of the transport device having a human occupant is located toward a center of the footprint of the transport device.
In another embodiment of the present invention a system for transporting a
Ambrogi Robert R.
Amsbury Burl
Dastous Susan D.
Duggan Robert J.
Heinzmann John David
DEKA Research and Development Corporation
Dickson Paul N.
Ilan Ruth
Wolf Greenfield and Sacks, P.C.
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