Patent Description:
The present invention generally relates to an adjustable height wheelchair and, more particularly, to a powered wheelchair that elevates from a lowered position to a raised position.

Wheelchairs are an important means of transportation for a significant portion of society and provide an important degree of independence for those they assist. However, this degree of independence can be limited if the wheelchair is required to traverse obstacles such as, for example, curbs that are commonly present at sidewalks and other paved surface interfaces, and door thresholds. Accordingly, powered wheelchairs have been the subject of increasing development efforts to provide handicapped and disabled persons with independent mobility to assist them in leading active lives.

To aid in climbing curbs, some power wheelchairs typically have a pair of forward extending anti-tip assemblies that are rotatably coupled to the wheelchair frame. The arms of the anti-tip assemblies are rotatably coupled to the wheelchair frame such that when the wheelchair encounters a curb, the anti-tip assemblies will pivot upwardly to thereby allow the wheelchair to traverse the curb. Some power wheelchairs also have elevatable seats that permit the occupant to move at "eye-level" with persons walking with them. However, wheelchairs operating with seats at elevated positions are susceptible to instability under certain conditions, and anti-tip assemblies, while beneficial for climbing obstacles such as curbs, may contribute to the instability when the wheelchair is operating on other than flat, level ground.

<CIT> discloses a wheelchair configured to reposition an occupant between a lowered and a raised position. The wheelchair can include a frame, a seat moveable relative to the frame, a drive wheel, and one or more pairs of arm assemblies. The arm assembly includes a wheel configured to move from a first spatial location when the wheel chair is operating on flat, level ground, to a second spatial location that is different than the first spatial location. The wheelchair can further include arm limiters, which can limit the range of motion of the arm assembly.

According to the invention there is a powered wheelchair comprising a frame; an arm assembly including an arm that is pivotably coupled to the frame, the arm assembly including a wheel coupled to the arm; a suspension coupled to the frame and to the arm assembly; a drive system coupled to the arm assembly and configured to drive a drive wheel; an arm limiter pivotably coupled to the suspension and coupled to one or more of the arm assembly and the drive system in an engaged position, the arm limiter being configured to limit movement of the arm assembly in the engaged position; and an expandable traction member coupled to one or more of the arm assembly and the drive system and to the frame, wherein the arm assembly includes a catch, and the arm limiter is coupled to the catch in the engaged position. In one embodiment, the arm limiter includes a latch arm, the latch arm having a notch for engaging a catch extending from the one or more of the arm assembly and the drive system in the engaged position. In one embodiment, the latch arm is bent generally in the shape of a question mark. In one embodiment, the arm limiter includes a spring coupled between the latch arm and the suspension, the spring being configured to bias the latch arm toward the engaged position. In one embodiment, the latch arm includes a free distal end configured to engage with a projection extending from a lift mechanism of the powered wheelchair.

In one embodiment, the expandable traction member is configured to bias the arm assembly upwardly relative to a ground surface. In one embodiment, the arm limiter is pivotably coupled to the suspension proximate where the expandable traction member is coupled to the frame.

In a further embodiment, the powered wheelchair includes a lift mechanism supported by the frame; and a seat supported by the lift mechanism, the lift mechanism configured to move the seat between a lowered position and a raised position. In one embodiment, the lift mechanism includes a projection configured to engage the arm limiter in the lowered position and release the arm limiter in the raised position and allow the arm limiter to transition to the engaged position. In one embodiment, the suspension includes a lever pivotably coupled to the frame and a compression spring coupled between the frame and the lever, the arm limiter being pivotably coupled to the lever. In one embodiment, the arm limiter is prevented from transitioning to the engaged position depending on the position of the arm assembly. In one embodiment, the drive system includes an electric motor and a gear box. In one embodiment, the drive system is rigidly coupled to the arm assembly and indirectly coupled to the frame by the arm assembly. In one embodiment, the arm limiter includes a sensor, the drive system being configured to drive the drive wheel at a reduced speed when the sensor detects that the arm limiter is in the engaged position.

In one embodiment, the powered wheelchair further comprises: a lift mechanism supported by the frame; a seat supported by the lift mechanism, the lift mechanism configured to move the seat between a lowered position and a raised position; a pair of drive wheels, wherein the drive is coupled to the frame and configured to apply a torque to at least one of the drive wheels; the arm configured to be in a first position relative to the frame when the powered wheelchair is operating on flat ground and to be rotatable from that first position; the arm limiter being configured to inhibit motion of the arm when the seat is in the raised position, the arm limiter having a first configuration in which the arm is rotatable from the first position through a first range of rotation, and a second configuration in which the arm is rotatable from the first position only through a second range of rotation that is smaller than the first range of rotation, the arm limiter coupled to the suspension and configured to engage the arm assembly in the second configuration; and a trigger mounted to the lift mechanism and coupled with the arm limiter such that as the seat is moved between the lowered and raised positions, the trigger causes the arm limiter to transition between the first and second configurations, wherein the arm limiter is prevented from transitioning into the second configuration when the arm is rotationally different from the first position relative to the frame by more than a predetermined amount.

In one embodiment, the trigger is configured to urge the arm limiter toward the first configuration as the lift mechanism moves the seat from the raised position to the lowered position. In one embodiment, the predetermined amount is greater than or equal to <NUM> degrees. In one embodiment, the trigger includes a projection projecting laterally from a side of the lift mechanism. In one embodiment, the expandable traction member has a first range of travel and the suspension has a second range of travel that is less than the first range of travel and wherein the suspension is configured to move through the second range of travel during operation of the powered wheelchair only when the arm limiter is in the second position. In one embodiment, the expandable traction member is configured to compress an amount that is less than the first range of travel when the arm limiter is in the second position. In one embodiment, the suspension is configured to compress through the entire second range of travel when the arm limiter is in the second position.

In one embodiment, the powered wheelchair further comprises: a lift mechanism supported by the frame; a seat supported by the lift mechanism, the lift mechanism configured to move the seat between a lowered position and a raised position; and a pair of drive wheels, wherein: the drive system is coupled to the frame and configured to apply a torque to at least one of the drive wheels; the arm is configured to be in a first position relative to the frame when the powered wheelchair is operating on flat ground and to be rotatable from that first position; the arm limiter is configured to inhibit motion of the arm when the seat is in the raised position, the arm limiter having a first configuration in which the arm is rotatable from the first position through a first range of rotation, and a second configuration in which the arm is rotatable from the first position only through a second range of rotation that is smaller than the first range of rotation, the arm limiter configured to engage the arm assembly in the second configuration; the powered wheelchair further comprises a trigger mounted to the lift mechanism and coupled with the arm limiter such that as the seat is moved between the lowered and raised positions, the trigger causes the arm limiter to transition between the first and second configurations, wherein the arm limiter is prevented from transitioning into the second configuration when the arm is rotationally different from the first position relative to the frame by more than a predetermined amount.

In one embodiment, the expandable traction member has a first range of travel and the suspension has a second range of travel wherein the expandable traction member is compressible through the first range of travel when the arm limiter is not in the engaged position and the suspension is compressible through the second range of travel when the arm limiter is in the engaged position. In one embodiment, the suspension and the expandable traction member are configured to control motion of the arm assembly relative to the frame depending upon a configuration of the arm limiter.

The following detailed description of embodiments of an adjustable height wheelchair will be better understood when read in conjunction with the appended drawings of an exemplary embodiment.

Referring to the drawings in detail, wherein like reference numerals indicate like elements throughout, there is shown in <FIG> an adjustable height wheelchair, generally designated <NUM>, an exemplary embodiment of the present invention. Various embodiments of the adjustable height wheelchair are described in further detail below in reference to the exemplary embodiment shown in the figures. Additional examples of powered wheelchairs having lift and suspension mechanisms are disclosed in <CIT> and <CIT>.

Referring to <FIG>, the adjustable height wheelchair <NUM> (also referred to as wheelchair <NUM>) may be configured to elevate a seated occupant and operate the wheelchair <NUM> in a safe, stable condition dependent on the occupant's position, ground surface features, and/or one more or more wheelchair operational parameters. The wheelchair <NUM> may be configured to elevate a chair or seat <NUM> between a conventional lowered position (e.g., <FIG>) and raised or elevated positions (e.g., <FIG> illustrate a partially elevated position and <FIG> illustrate a fully elevated position). Providing an adjustable height wheelchair <NUM> may allow an occupant to operate the wheelchair <NUM> with the seat <NUM> in the raised position, which in some circumstances can be at a conversational or eye-to-eye level height with others who are standing or walking along with the wheelchair <NUM>. In one embodiment, the wheelchair <NUM> raises the seat <NUM> more than <NUM>,<NUM> (<NUM> inches) above its most lowered state. In one embodiment, the wheelchair <NUM> raises the seat <NUM><NUM>,<NUM> (<NUM> inches) above its most lowered state. In one embodiment, the wheelchair <NUM> raises the seat <NUM><NUM>,<NUM> (<NUM> inches) above its most lowered state. In one embodiment, the wheelchair <NUM> raises the seat <NUM><NUM>,<NUM> (<NUM> inches) above its most lowered state. In one embodiment, the wheelchair <NUM> raises the seat <NUM><NUM>,<NUM> (<NUM> inches) above its most lowered state. In one embodiment, the wheelchair <NUM> raises the seat <NUM> more than <NUM>,<NUM> (<NUM> inches).

The wheelchair <NUM> may be a powered wheelchair. In some embodiments, wheelchair <NUM> may be configured to selectively limit certain operational aspects when, for example, the wheelchair <NUM> is in the process of traversing an obstacle, is on un-level ground, and/or when the seat <NUM> is raised. Likewise, the wheelchair <NUM> may prevent the raising of the seat <NUM> when the wheelchair <NUM> is climbing an obstacle or is on unlevel ground. An "obstacle" <NUM> as the term is used herein may include any relatively raised or lowered structure on the ground surface G that the wheel must ascend or descend to cross over (see <FIG>). Operating a wheelchair when the seat is in the elevated position can create instability, especially when climbing curbs or transitioning to a descent when appropriate safety features are not deployed. For instance, when the seat <NUM> is in the fully raised position, the center of gravity of the occupied wheelchair is also elevated and/or shifted forward or rearward (depending, for example, on the lift mechanism associated with the chair). The risk of tipping can increase on an incline and overall wheelchair stability can be compromised, especially when traversing or attempting to traverse an obstacle.

The wheelchair <NUM> may be configured with supplemental stability features when the seat <NUM> is in the elevated position. The supplemental stability configuration may permit wheelchair <NUM> to operate at increase travelling speeds when the chair is elevated as compared to elevated height wheelchairs that are not so configured. Increased traveling speeds may include walking, jogging, or running speeds. Conversational height as used herein refers to when the occupant is elevated to a level above the ground surface G (see <FIG>) to make communication with others (e.g., average height adult males or females) standing or walking next to the wheelchair <NUM> easier. For example, conversational height could place the user "eye-level" with someone standing next to the wheelchair <NUM>.

With continued reference to <FIG>, the powered wheelchair <NUM> may include a frame <NUM> (see <FIG>), a pair of drive wheels <NUM> coupled to the frame <NUM> and driven by at least one drive system <NUM> (see <FIG>). A pair of front anti-tip arm assemblies <NUM> may extend from the frame <NUM> in a forward direction F relative to the drive wheels <NUM>. A pair of rear anti-tip arm assemblies <NUM> may extend from the frame <NUM> in a rearward direction R that is opposite to the forward direction F. As used herein the forward-rearward direction F-R may refer the horizontal direction when the wheelchair is operating on flat, level ground. In accordance with the illustrated embodiment, the wheelchair <NUM> may be a mid-wheel drive power wheelchair and include front wheels <NUM> and rear wheels <NUM> disposed in the forward and rearward directions F and R relative to the drive wheels <NUM>, respectively. The drive system <NUM> may include an electric motor and gear box configured to cause the drive wheels <NUM> to rotate about the drive wheel axis A<NUM> to advance the wheelchair <NUM> along the surface G. The front wheel <NUM> may be rotatable about the front wheel axis A<NUM> and the rear wheel <NUM> may be rotatable about the rear wheel axis A<NUM>. The present disclosure, however, is not limited to mid-wheel powered wheel chairs and may include any number of wheels.

Referring to <FIG>, the powered wheelchair <NUM> may also include a lift mechanism <NUM> mounted to the frame <NUM> with the seat <NUM> supported by the lift mechanism <NUM>. The lift mechanism <NUM> may be configured to, in response to inputs an occupant applies to an input device for example, move the seat <NUM> between a lowered position (<FIG>) and a raised position (<FIG>) generally along a vertical direction V (see <FIG>) that is substantially perpendicular the forward and rearward directions F and R. The lift mechanism <NUM> may include a telescopic pillar mechanism as shown. The lift mechanism <NUM> may include a screw type actuator. In one embodiment, the lift mechanism <NUM> includes two or more housing segments (e.g., 30a, 30b, 30c) that are telescopically coupled to one another to cover the actuator. In one embodiment, the housing segments 30a, 30b, 30c are arranged such that the top segment 30c slides over the middle segment 30b which slides over the bottom segment 30a. The housing segments (e.g., 30a, 30b, 30c) may have a non-circular cross sectional shape to prevent the chair <NUM> from rotating relative to the frame <NUM>. In one embodiment, the housing segments (e.g., 30a, 30b, 30c) are generally rectangular in cross sectional shape. In other embodiments, the housing segments (e.g., 30a, 30b, 30c) are generally triangular or oval in cross sectional shape. In other embodiments, the housing segments (e.g., 30a, 30b, 30c) are generally circular in cross sectional shape to allow the chair <NUM> to rotate relative to the frame <NUM>.

In other embodiments, another type of lift mechanism may be employed such as a scissor lift. Further, the wheelchair <NUM> can be configured to move the seat <NUM> into the raised position and tilt the seat base and seat back relative to each other in the raised position. In an embodiment, the wheelchair <NUM> can include a lift and tilt mechanism, such as the lift and tilt mechanism disclosed in <CIT>, entitled "Lift Mechanism And Tilt Mechanism For A Power Wheelchair".

The lift mechanism <NUM> may include a trigger 30d. The trigger 30d may include a block extending laterally from the lift mechanism <NUM>. In one embodiment, the trigger 30d extends from the outermost top segment 30c. In one embodiment, a trigger 30d extends from each lateral side of the lift mechanism <NUM> in direction generally perpendicular to the forward F and rearward R directions (see <FIG>). The trigger 30d may be configured to engage and release an arm limiter as discussed in further detail below.

Turning to <FIG> and <FIG>, as noted above, the wheelchair <NUM> includes a pair of front anti-tip arm assemblies <NUM>. For ease of illustration only one anti-tip arm assembly <NUM> is shown and described below. The other anti-tip assembly <NUM> in the pair preferably has the same structure but oriented on the opposite side of the wheelchair <NUM>. The anti-tip arm assembly <NUM> may also be referred to in this disclosure as an arm assembly <NUM>. In one embodiment, the arm assembly <NUM> is rotatable coupled to frame <NUM>. For example, the arm assembly <NUM> may include an arm member <NUM> rotatably coupled to the frame <NUM>. A front wheel <NUM> may also be coupled to the arm assembly (e.g., the wheel <NUM> may be coupled to the arm member <NUM>). The arm member <NUM> may include an arm extension 32a. The arm extension 32a may extend downwardly from the arm member <NUM>. In one embodiment, the arm extension 32a is hook shaped (see <FIG>). In one embodiment, the arm extension 32a is rigidly connected to the arm member <NUM>. The arm extension 32a may be pivotably coupled to the frame <NUM>. In one embodiment, arm assembly <NUM> may be directly coupled to frame <NUM> only via arm extension 32a. In one embodiment, the arm extension 32a is pivotably coupled to the frame <NUM> about axis A<NUM>. In one embodiment, axis A<NUM> is generally parallel with axis A<NUM> (see <FIG>). The arm member <NUM> and arm extension 32a can be formed of multiple components that are connected together with fasteners or welds, or pivotally attached together, without limitation. In other embodiments, the arm member <NUM> and arm extension 32a can be a monolithic structure, such as a cast or extruded material.

Referring to <FIG>, the front wheel <NUM> is coupled to the distal end of the arm assembly <NUM> and is rotatable about the front wheel axis A<NUM>. As illustrated, the front wheel <NUM> is in contact with ground or surface G during normal operation. The front wheel <NUM> may be part of a caster assembly. The caster assembly rotatably couples the front wheel <NUM> to the arm member <NUM> such that front wheel <NUM> is rotatable about an axis that is generally perpendicular to the ground surface G and perpendicular the wheel axis A<NUM>. In some embodiments, the front wheel <NUM> can be an anti-tip wheel that is raised or otherwise spaced from the ground or surface G during normal operation in a configuration that does not include a caster. The term "anti-tip" wheel as used herein encompasses caster wheel assemblies (that may include for example, front wheel <NUM>) and anti-tip wheels that are raisable during normal operation and encompasses wheels in the front and the rear of the wheelchair <NUM>. In some embodiments, the raisable anti-tip wheels can have a first or rest position when the wheelchair <NUM> is operating on flat, level ground G.

The arm assembly <NUM> may be coupled to the frame <NUM> and configured to move the wheel <NUM> relative to the frame <NUM> upon encountering an obstacle <NUM>. The arm assembly <NUM> may be pivotably coupled the frame <NUM> such that the arm assembly <NUM> and wheel axis A<NUM> pivot about the pivot axis A<NUM>. It should be appreciated, however, that the arm assemblies <NUM> can be coupled to the frame <NUM> such that the arm member <NUM> and wheel axis A<NUM> translate relative to the frame <NUM>.

Referring to <FIG> and <FIG>, the arm assembly <NUM> may be coupled to the drive system <NUM>. The drive system <NUM> may be rigidly coupled to the arm assembly <NUM> and indirectly coupled to the frame <NUM> by, for example, the arm assembly <NUM>. In one embodiment, the drive system <NUM> and the arm assembly <NUM> are configured to pivot relative to the frame <NUM> together about a common axis A<NUM>. Coupling the drive system <NUM> and the arm assembly to one another may allow for a simplified suspension system such as those described in further detail below. In one embodiment, the arm assembly <NUM> is coupled to the drive system <NUM> at a plurality of points (e.g., P<NUM>, P<NUM>, P<NUM>) around the drive axis A<NUM>. In one embodiment, the arm assembly <NUM> is coupled to the drive system <NUM> at the plurality of points (e.g., P<NUM>, P<NUM>, P<NUM>) via a fasener such as a bolt. In one embodiment, a tie bar <NUM> extends between two (or at least two) of the points (e.g., P<NUM> and P<NUM>). Because the tie bar <NUM> may be rigidly coupled to both the arm assembly <NUM> and the drive system <NUM>, the tie bar <NUM> in some embodiments may be considered to be part of the arm assembly <NUM> or part of the drive system <NUM>. In other embodiments, the drive system <NUM> may be moveably connected to the arm assembly <NUM>, at least initially, to allow the drive system <NUM> to rotate relative to the frame <NUM> a predetermind amount before moving simultaneously with the arm assembly <NUM>.

Referring to <FIG>, a traction member <NUM> may be coupled between one or more of the arm assembly <NUM> and the drive system <NUM> and to the frame <NUM>. For example, traction member <NUM> may be coupled between the arm assembly <NUM> and the frame <NUM>, or traction member <NUM> may be coupled between the drive system <NUM> and to the frame <NUM>. The traction member <NUM> may include a biasing member such as a tension spring or in some embodiments, a compression spring. In one embodiment, the traction member <NUM> is provided to urge the drive wheel <NUM> downward so that the drive wheel <NUM> maintains contact with the ground surface G. In one embodiment, the traction member <NUM> is coupled to a bracket 34a extending from the tie bar <NUM> at one end and to an extension arm 16a of the frame <NUM> at another end.

Referring to <FIG>, the wheelchair may include one or more arm limiters <NUM> configured to selectively engage one or more of the arm assemblies <NUM> so as to inhibit relative motion between the one or more arm assembly assemblies <NUM> and frame <NUM>. In one embodiment, an arm limiter <NUM> is configured to automatically engage one or more of the arm assemblies upon the occurrence of a predefined operational condition of in certain instances during operation of the wheelchair <NUM> (e.g., when the wheelchair is in an elevated condition). The arm limiter <NUM> may be coupled to the frame <NUM>. In some embodiments, the arm limiter <NUM> is indirectly coupled to the frame <NUM> by a suspension as discussed below. When the wheelchair <NUM> is in an elevated position and the center of gravity is raised, the arm assembly <NUM> without arm limiter <NUM> may not provide sufficient support and result in instability or tipping of the chair. Preventing relative motion between the arm assembly <NUM> and the frame <NUM> can limit certain operation conditions of the wheelchair <NUM> in order to improve stability and occupant safety. The arm limiter <NUM> may transition between a first or disengaged configuration and a second or engaged configuration where operational movement of the arm assembly <NUM> is limited. Further, operation of arm limiter <NUM> may be limited, inhibited, impaired or delayed when the wheelchair is traversing an obstacle <NUM>. For instance, the arm limiter <NUM> may not transition into an engaged configuration if the arm assembly <NUM> is engaged in attempting to traverse an obstacle <NUM>, as will be further discussed below.

Referring to <FIG> and <FIG>, the wheelchair <NUM> may include an obstacle suspension <NUM>. The obstacle suspension <NUM> may include a biasing member such as a compression spring <NUM>. The suspension <NUM> may be coupled to the arm limiter <NUM> (e.g., at one end of the obstacle suspension <NUM>) and the frame <NUM> (e.g., at another end of the obstacle suspension <NUM>) to couple the arm limiter <NUM> to the frame <NUM>. In one embodiment, the suspension <NUM> is considered part of the arm limiter <NUM>. The suspension <NUM> may be pivotably coupled to frame <NUM> - about axis As, for example. In one embodiment, obstacle suspension <NUM> may include a lever <NUM> pivotably coupled to the frame <NUM> about axis A<NUM>. In one embodiment, axis A<NUM> is generally parallel with axis A<NUM>. In one embodiment, axis A<NUM> is proximate axis A<NUM>. In one embodiment, axis A<NUM> is positioned between axis A<NUM> and the wheel <NUM>. The lever <NUM> may be coupled to the frame <NUM> by a fastener such as a bolt. A fastener <NUM>, such as a bolt, may be coupled to the frame <NUM>, extend through the compression spring <NUM> and be coupled to the lever <NUM>. The suspension <NUM> is configured to resist the pivoting of arm assembly <NUM> relative to the frame. For example, the suspension <NUM> may be configured to resist an upward movement (in the vertical direction V, see <FIG>) of wheel <NUM> and/or an upward impact on wheel <NUM>.

The arm limiter <NUM> is configured to limit movement of the arm assembly <NUM> relative to the frame in an engaged position. The engaged position may include a configuration in which the arm limiter <NUM> may be coupled to the suspension <NUM> and coupled to one or more of the arm assembly <NUM> and the drive system <NUM>. In one embodiment, the arm limiter <NUM> is configured to engage the tie bar <NUM> in the engaged position. In one embodiment, the arm limiter <NUM> is configured to engage a catch 34b extending from the tie bar <NUM> in the engaged position. The arm limiter <NUM> may be pivotably coupled to the obstacle suspension <NUM>. In one embodiment, the arm limiter <NUM> is pivotably coupled to the obstacle suspension <NUM> about axis A<NUM>. In one embodiment, axis A<NUM> is generally parallel to axis A<NUM>. In one embodiment, arm limiter <NUM> is coupled to the obstacle suspension <NUM> proximate where the traction member <NUM> is coupled to the frame <NUM>.

The arm limiter <NUM> may be in the form of a latch arm. The arm limiter <NUM> may have a first notch 46a configured to engage the catch 34b extending from the tie bar <NUM> in the engaged position. The arm limiter <NUM> may include a second notch 46b configured to engage the catch 34b extending from the tie bar <NUM> in the disengaged position. The arm limiter <NUM> may be bent generally in the shape of a question mark. In one embodiment, arm limiter <NUM> is biased to pivot toward obstacle suspension <NUM> - for example, into a position that reduce a range of travel of obstacle suspension <NUM> as described herein. In one embodiment, a biasing member such as a tension spring <NUM> is coupled between the arm limiter <NUM> and the suspension <NUM>. The spring <NUM> being configured to bias the arm limiter <NUM> toward the engaged position. The arm limiter <NUM> may be shaped such that the first and second notches 46a, 46b are within a pocket between the spring <NUM> and arm limiter <NUM>. The arm limiter <NUM> may have a distal end 46c that is configured to engage with the trigger 30d of the lift mechanism. In one embodiment, the distal end 46c of the latch arm is a free end. The distal end 46c may be shaped to be generally parallel with axis A<NUM>.

Referring to <FIG> and <FIG>, the arm limiter <NUM> is shown in the disengaged position. On level ground G such as shown in <FIG>, with the seat in the lowered position, the trigger 30d may engage the arm limiter <NUM> (e.g., at the distal end of the arm limiter <NUM>) and space the arm limiter <NUM> from the catch 34b. When the wheel <NUM> encounters an obstacle <NUM> such as shown in <FIG>, the arm assembly <NUM> is pivoted relative to frame <NUM> an angle β<NUM> until the catch 34b engages a second notch 46b of the arm limiter pivoting the arm limiter <NUM> relative to the suspension <NUM>. The arm assembly <NUM> may pivot relative to the frame (e.g., about axis A<NUM>) until the spring <NUM> (see <FIG>) of the suspension <NUM> is fully compressed. In other embodiments, the vertical pivot limit of the arm assembly <NUM> is dictated by a limit of the traction member <NUM>. As illustrated in <FIG>, the arm limiter <NUM> is prevented from transitioning to the engaged position depending on the position of the arm assembly <NUM>.

Referring to <FIG> and <FIG>, the arm limiter <NUM> is shown in the engaged position. On level ground G such as shown in <FIG>, with the seat in the elevated position, the trigger 30d may be disengaged from the distal end of the arm limiter <NUM> such that the biasing member <NUM> pivots the arm limiter <NUM> relative to arm assembly <NUM> until the first notch 46a of the arm limiter <NUM> is engaged with the catch 34b. When the wheel <NUM> encounters an obstacle <NUM> such as shown in <FIG>, the arm assembly <NUM> is pivoted relative to frame <NUM> an angle β<NUM> until the spring <NUM> of the suspension <NUM> is fully compressed. In one embodiment, lowering the seat <NUM> causes the trigger 30d to engage the distal end of the arm limiter <NUM>, releasing the arm limiter <NUM> from the catch 34b. In one embodiment wheelchair <NUM> includes a sensor <NUM> for detecting when the arm limiter <NUM> is in the engaged position. The sensor <NUM> may be a contact sensor, an electromagnetic sensor and/or a proximity sensor. The sensor <NUM> may be positioned on or proximate to catch 34b. In one embodiment, the arm limiter <NUM> includes a sensor <NUM> proximate the first notch 46a. Such a sensor <NUM> may indicate to a controller that the arm limiter <NUM> is in the engaged position. In one embodiment, a controller receives a signal from sensor <NUM> that indicates arm limiter <NUM> is in the engaged position and in response to the signal generates a control signal that implements a selected and select a desired operation of the wheelchair <NUM> as discussed in further detail below.

Referring to <FIG>, the wheelchair <NUM> may have different operational modes, such as a standard mode and one or more elevated motion modes. In some embodiments, a control system includes a controller configured to operate the wheelchair <NUM> in the different operational modes, an input device in electronic communication with the controller, and one or more sensors in electronic communication with the controller. The controller may be responsive to inputs from the input device and one or more of the sensors in order to cause the wheelchair <NUM> to operate at least in (i) a standard mode when the seat <NUM> is in the lowered position such that the wheelchair <NUM> is moveable along the surface G in accordance with standard drive parameters (that is, conventional parameters that are not limited for elevated seat operation), and (ii) one or more elevated motion modes whereby the seat <NUM> is in the raised position and drive parameters are limited to some extent. The elevated motion modes may include A) a first or normal elevated motion mode where the wheelchair is capable operating according to a first set of limited drive parameters, and B) a second elevated motion mode (sometimes referred to as an elevated-inhibited mode) whereby the wheelchair <NUM> is capable of operating according to a second set of limited drive parameters that have limits that are typically less than upper limits of the first set of limited drive parameters. The phrase "drive parameters" as used herein (whether in standard or elevated modes) may include a speed (miles/hr), acceleration, and deceleration of the wheelchair <NUM>. In some embodiments, the drive parameters include directional components, such as forward speed, reverse speed, and turn speed, forward acceleration, forward deceleration, reverse acceleration, and reverse deceleration. For brevity and ease of illustration, the standard and elevated modes below are described with reference to the speed of the wheelchair <NUM>. However, it should be appreciated that the ranges and limits discussed below with respect to speed are applicable to the other drive parameters such as turn speed, acceleration, and deceleration described above.

In one embodiment, the standard mode may be when the seat <NUM> is in the lowered position such that the wheelchair is moveable along the surface G at typical wheelchair speeds. The first elevated motion mode can be when the wheelchair <NUM> is capable of moving at a first speed range, up to a maximum raised-seat drive speed, which is less than the typical wheelchair speeds. The second elevated motion mode (or an elevated-inhibited mode) is when the wheelchair <NUM> is capable of moving at a second elevated mode speed range, up to a maximum raised-inhibited drive speed that is less than the upper limit of the first speed range.

In the standard mode the wheelchair <NUM> may move at a standard or lowered-seat drive speed range that is typical of conventional wheelchairs, such from <NUM> kph (<NUM> mph) to about <NUM>,<NUM> kph (<NUM> mph) Accordingly, it should be appreciated that the fully lowered-seat drive speed can have an upper limit that is anywhere in the conventional range from a practical minimum (or at rest at <NUM> kph (<NUM> mph)) to, for example, <NUM>,<NUM> kph (<NUM> mph) as indicated. Furthermore, it should be appreciated that when the wheelchair <NUM> is operating in the standard mode, the wheelchair <NUM> can be configured to move at any speed as desired and is not limited to a speed that is between the practical minimum and <NUM>,<NUM> kph (<NUM> mph) The powered wheelchair <NUM> would typically be in the standard mode (that is, with the seat in the fullylowered position) when the wheelchair <NUM> is traversing obstacle <NUM> such as a curb. The term "standard mode" includes a mode that has no speed restrictions by the controller that are related to seat position.

When in the elevated motion modes, the wheelchair <NUM> may be configured to move at a speed that has a limit that is less than the standard mode drive speed upper limit. In the elevated motion modes, the wheelchair <NUM> preferably is capable of moving at a walking speed (or perhaps faster) while seat <NUM> is in the raised position such that the occupant is at the conversational height with a person walking next the powered wheelchair. In an exemplary embodiment, when in the normal elevated motion mode, the first speed range is from a practical minimum to <NUM>,<NUM> kph (<NUM> mph), preferably from the practical minimum to <NUM>,<NUM> kph (<NUM> mph). That is, the wheelchair <NUM> can be configured to move at a maximum raised-seat drive speed that is no more than <NUM>,<NUM> kph (<NUM> mph), preferably no more than <NUM>,<NUM> kph (<NUM> mph). In one embodiment, the wheelchair <NUM> is configured to move at a maximum raised-seat drive speed that is no more than <NUM>,<NUM> kph (<NUM> mph). It should be appreciated that the raised-seat drive speed can have an upper limit that is anywhere from a first speed range of the practical minimum to <NUM>,<NUM> kph (<NUM> mph). Furthermore, when the wheelchair <NUM> is operating in the normal elevated motion mode, there may be circumstances in which the upper limit may be set higher than <NUM>,<NUM> kph (<NUM> mph). The term "practical minimum" speed as used herein means that the lower limit of the range is chosen according to the parameters understood by persons familiar with wheelchair structure and function, and may be close to zero mph under some conditions.

In an instance in which wheelchair <NUM> is operating in the elevated motion mode, and at least one safety criteria is not met, the controller may cause the wheelchair <NUM> to operate in some mode other than the first, normal elevated motion mode. For example, the controller may cause the wheelchair <NUM> to operate in the second elevated motion mode or elevated inhibited mode at least until all of the safety criteria are met. For example, in some embodiments, if the seat <NUM> is in the raised position and one of the safety criteria is not met, the controller may allow the wheelchair <NUM> to move within the second, elevated-inhibited speed range, up to the reduced maximum raised-inhibited speed that is less then maximum raised-seat drive speed. The maximum raised-inhibited drive speed can be a speed that is no more than <NUM>,<NUM> kph (<NUM> mph), preferably no more than <NUM>,<NUM> kph (<NUM> mph). In one embodiment, the maximum raised-inhibited drive speed can be a speed that is no more than <NUM>,<NUM> kph (<NUM> mph). It should be appreciated, however, that the raised-inhibited drive speed can have any upper limit as desired so long as it is less than an upper limit of the first, normal speed range.

The maximum speed of the wheelchair may be reduced when one or more of the arm limiters is not engaged in the elevated position. In one embodiment, the maximum standard or lowered-seat drive speed is approximately <NUM>,<NUM> kph (<NUM> mph), the maximum elevated motion mode speed with both arm limiters engaged is approximately <NUM>,<NUM> kph (<NUM> mph), and the maximum elevated motion mode speed with one or more arm limiters not engages is approximately <NUM>,<NUM> kph (<NUM> mph).

Accordingly, in order for the wheelchair <NUM> to operate in the elevated motion modes, certain safety criteria should be satisfied as will be discussed further below. One or more senors may detect information indicative of when the wheelchair <NUM> is in a position to safely operate in the elevated motion modes. Those sensors may include contact sensors, electromagnetic sensor and/or proximity sensors. If the sensors detect a condition that indicates that it is not safe to operate the wheelchair <NUM> in the elevated motion mode, the controller may operate the wheelchair <NUM> in some other mode such as the elevated inhibited mode or standard mode (that is, by requiring the seat <NUM> to be in the lowermost position). In certain instances, for example, the wheelchair <NUM> will not operate in the elevated motion modes, i.e., the seat <NUM> will not move into the raised position if the seat <NUM> is initially in the lowered position and the wheelchair <NUM> is ascending an obstacle or descending down an incline.

Arm assembly <NUM> may have a variety of different ranges of motion depending on the state of wheelchair <NUM>. The range of rotation as used herein refers to rotation of the arm assembly <NUM> to a position that is different than a first position (e.g., the position illustrated in <FIG>). When the arm assembly <NUM> is in the first position, such that the wheelchair <NUM> is operating on flat, level ground G, a first, fixed reference line L intersects the pivot axis A<NUM> and the front wheel axis A<NUM>. The line L defines an angle α from the ground surface G in the first position. In one embodiment, the angle α is approximately <NUM> degrees. In other embodiments, the angle α may be approximately <NUM> degrees, <NUM> degrees, <NUM> degrees, or <NUM> degree. Referring to <FIG>, the arm assembly <NUM> may have a first range of motion relative to frame <NUM> in the disengaged position such that reference line L is movable up to an angle β<NUM> relative to the ground surface G. In one embodiment, the angle β<NUM> is approximately <NUM> degrees. In other embodiment, the angle β<NUM> may be approximately <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees or <NUM> degrees. Referring to <FIG>, the arm assembly <NUM> may have a second range of motion relative to frame <NUM> in the engaged position such that reference line L is movable up to an angle β<NUM> relative to the ground surface G, the angle β<NUM> being less than angle β<NUM>. In one embodiment, the angle β<NUM> is approximately <NUM> degrees. In other embodiment, the angle β2 may be approximately <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees, <NUM> degrees or <NUM> degrees. In one embodiment, the angle β<NUM> is approximately <NUM>/3rds of angle β<NUM>. In one embodiment, the angle β<NUM> is less than approximately <NUM>/3rds of angle β<NUM>. In one embodiment, angle β<NUM> is approximately <NUM>/<NUM> the value of angle β<NUM> In one embodiment, the bottom of the front wheel <NUM> lifts no more than approximately <NUM>,<NUM> (<NUM>") off ground G in the engaged position. In one embodiment, the bottom of the front wheel <NUM> lifts no more than approximately <NUM>,<NUM> (<NUM>") off ground G in the engaged position. In one embodiment, the bottom of the front wheel <NUM> lifts no more than approximately <NUM>,<NUM> (<NUM>") off ground G in the engaged position. In one embodiment, the bottom of the front wheel <NUM> lifts no more than approximately <NUM>,<NUM> (<NUM>") off ground G in the engaged position.

The arm limiter <NUM> may be disengaged when the wheelchair <NUM> is operating in the standard motion mode, i.e., when the seat <NUM> is in the lowered position. When the controller receives an input from the input device to operate the wheelchair <NUM> in the elevated motion mode, the controller may causes the arm limiter to transition into the second or engaged configuration. However, if certain conditions are not met, the arm limiter <NUM> may be inhibited from moving into the engaged position. For example, the arm limiter <NUM> may be able to move into the engaged position only when the front wheel <NUM> and drive wheel <NUM> are on flat, level ground G (or substantial flat, level ground). If the front wheel <NUM> is on a surface that is raised relative to the drive wheel <NUM> and to ground surface G such that the arm assembly <NUM> is pivoted vertically as shown in <FIG>, then the arm limiter <NUM> is physically blocked from moving into the engaged position (e.g., the catch 34b has already passed the first notch 46a. If the front wheel <NUM> then returns to the ground plane G, biasing or tension spring <NUM> may cause the arm limiter <NUM> to move to the engaged position. If the lift mechanism <NUM> is lowered while the front wheel <NUM> is on a raised surface relative to ground plane G, trigger 30d may cause the arm limiter <NUM> to rotate about its axis A<NUM> and allow arm <NUM> to rotate beyond the raised angle limit without causing undue stress or damage to components of the wheelchair <NUM>.

In one embodiment, wheelchair <NUM> includes a suspension means for controlling motion of arm assembly <NUM> relative to frame <NUM> depending upon a configuration of arm limiter <NUM> (e.g., depending upon whether the arm limiter is in the engaged position or not in the engaged position). The suspension means consists of an expandable traction member <NUM> and a suspension <NUM> (illustrated for example in <FIG>). In one embodiment, the expandable traction member has a first range of travel and the suspension has a second range of travel that is less than the first range of travel. The suspension may be configured such that the first range of travel is only achieved (e.g., when the first suspension component is fully compressed) when the arm limiter is not in the engaged position. The suspension means may also be configured such that the second range of travel is only achieved (e.g., when the second suspension component is fully compressed) when the arm limiter is in the engaged position. In one embodiment, arm limiter <NUM>, the suspension (e.g., obstacle suspension <NUM>) and the expandable traction member (e.g., traction member <NUM>) are coupled (e.g., each being rotatably coupled) to wheelchair <NUM> at a common axis (e.g., axis A6 illustrated, for example, in <FIG>).

Claim 1:
A powered wheelchair (<NUM>) comprising:
a frame (<NUM>);
an arm assembly (<NUM>) including an arm (<NUM>) that is pivotably coupled to the frame (<NUM>), the arm assembly (<NUM>) including a wheel (<NUM>) coupled to the arm (<NUM>);
a suspension (<NUM>) coupled to the frame (<NUM>) and to the arm assembly (<NUM>), the suspension (<NUM>) configured to resist pivoting of the arm assembly (<NUM>) relative to the frame (<NUM>);
a drive system (<NUM>) coupled to the arm assembly (<NUM>) and configured to drive a drive wheel (<NUM>);
an arm limiter (<NUM>) pivotably coupled to the suspension (<NUM>) and coupled to one or more of the arm assembly (<NUM>) and the drive system (<NUM>) in an engaged position, the arm limiter (<NUM>) being configured to limit movement of the arm assembly (<NUM>) in the engaged position; and
an expandable traction member (<NUM>) coupled to one or more of the arm assembly (<NUM>) and the drive system (<NUM>) and to the frame (<NUM>),
wherein the arm assembly (<NUM>) includes a catch (34b), and the arm limiter (<NUM>) is coupled to the catch (34b) in the engaged position.