Patent Description:
Vehicles, especially in the European Union, are getting smaller. With the limited space in these vehicles, proper use of a wheelchair securement system becomes difficult. In small spaces, such as the space in rear-entry, wheelchair accessible vehicle (which makes up a large majority of the personal mobility wheelchair accessible vehicles), it is important that the wheelchair securement system is simple and safe to use. Occupants in wheelchairs who are not able to transfer or move into a vehicle chair usually depend on the wheelchair securement assemblies (also referred to as wheelchair tie-downs or wheelchair tie-down assemblies) to safely secure their wheelchair while traveling.

Existing securement systems used in smaller, more compact vehicles with tight and confined wheelchair spaces suffer from many drawbacks, some of which are described below. Rear-entry vehicles, such as the Citroën Berlingo, Nissan NV200, and Peugeot Expert (also known as or referred to as rear-entry wheelchair accessible vehicles, WAV, M1, or mini-vans), in general, do not offer much space for the front of a wheelchair to be secured after it is in place in the securement area of the vehicle. These vehicles provide only a small "wheelchair pan" (or securement area) in the rear of the vehicle for securing the wheelchair. See, in particular, <CIT>, As such, it is important for a fully integrated system in a rear-entry vehicle to be useable from behind the wheelchair passenger as much as possible.

In addition, rear-entry vehicles often have ramps and sloping floors (some at about <NUM>°) which create a challenge in terms of strength requirements to push a heavy passenger and wheelchair up into the vehicle, and sometimes lead to injuries for the vehicle driver and/or the wheelchair passenger. Operators face similar challenges when removing the wheelchair passenger from the vehicle; wheelchair passengers must be carefully supported while descending the incline to avoid "dropping" the occupant. To address this problem, additional devices such as a front electrical winch are used to aid entry into the vehicle. These electrical winches, however, do not fully solve the problem. The winches are provided with long cables or straps (e.g., webbing) that can extend outside of the vehicle for attachment to the front of the wheelchair. The winches are then used to pull the wheelchair up the ramp. To keep the wheelchair aligned on the ramp, however, the vehicle driver must still steer or guide the wheelchair up the vehicle ramp by hand. This occurs frequently not only because vehicles rarely park on perfectly even surfaces, but also because wheelchairs are not normally balanced in weight, sometimes have uneven tire pressure, sometimes have additional accessories or lean causing it to go off course, and/or have wheel casters that alter the direction of the wheelchair. The risk of injury, therefore, to both the driver and wheelchair passenger has not been fully mitigated by the use of electrical winches.

<CIT> discloses a motorized wheelchair which includes left and right drive wheels, with left and right motors. A controller of the wheelchair may be arranged to detect drift from signals provided by sensors.

Moreover, the electrical winches of the prior art are typically not adequate to secure the wheelchair once positioned in the vehicle. For that reason, the prior art systems typically utilize separate front tie-downs as necessary additional components to adequately secure the wheelchair.

The embodiments described and claimed herein solve at least some of the problems of the prior art. For example, one embodiment comprises two front, electronically-controlled retractor units that would be able to fit underneath the front seats or other structures in the vehicle. These retractors would have three core functions: (<NUM>) to work as a wheelchair front tie-down and secure the wheelchair during transportation and in the event of a crash restrain the wheelchair (during front and rear impact); (<NUM>) to lock or tension the webbing/material in the retractor such that rearward excursion in the event of a crash is kept to a minimum; and (c) to function as a winch and move the wheelchair and passenger into and out of a vehicle in a controlled manner.

It is contemplated that the electronically-controlled retractor units would allow the operator (e.g., the vehicle driver or attendant) to load and secure a passenger safely from outside of the vehicle, without having to push, pull, or steer the passenger in/out of the vehicle by hand. In particular, with the rear-entry vehicle ready to accommodate the wheelchair passenger, the operator will pull the front tie-downs from the retractor down the ramp and outside of the vehicle. The operator will attach the tie-downs onto the front structural members of the wheelchair (the wheelchair passenger will, of course, be present at the bottom of the ramp with wheels unlocked, but need not be perfectly aligned as with prior art systems). The operator will remotely activate the retractor units using a wired pendant or wireless control module (e.g., radio, wi-fi, Bluetooth, etc.). The retractor units are motorized and will pull the passenger up the ramp and into the vehicle. The operator controls the ascension speed and steers the wheelchair up the ramp by use of a thumbstick on the pendant/remote, and will stop the unit by releasing the thumbstick once the wheelchair passenger is located within the securement area of the vehicle. The operator will affix rear securements (e.g., manual belts, retractors, or other cable or strap devices) to the rear structural members of the wheelchair. The operator will then operate the motorized front retractor units to remove slack from and tension all restraints in the system, and apply occupant restraints to secure the occupant in the wheelchair. The wheelchair and occupant will then be properly secured by the system, at which point the wheelchair passenger is free to be transported to his/her destination. Upon arrival, the above steps are reversed in order to egress the wheelchair passenger.

According to the present invention, there is provided a wheelchair accessible vehicle as defined in claim <NUM>.

These and other features, aspects, objects, and advantages of the embodiments described and claimed herein will become better understood upon consideration of the following detailed description, appended claims, and accompanying drawings where:.

It should be understood that the drawings are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom lines, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the embodiments described and claimed herein or which render other details difficult to perceive may have been omitted. It should be understood, of course, that the inventions described herein are not necessarily limited to the particular embodiments illustrated. Indeed, it is expected that persons of ordinary skill in the art may devise a number of alternative configurations that are similar and equivalent to the embodiments shown and described herein without departing from the spirit and scope of the claims.

Like reference numerals will be used to refer to like or similar parts from Figure to Figure in the following detailed description of the drawings.

Referring first to <FIG>, the incline tie-down system <NUM> of the first embodiment comprises, but is not limited to, two electronically-controlled front tie-down units <NUM>, a controller <NUM>, a control panel <NUM>, a joystick <NUM>, and two rear tie-down units <NUM>. The incline tie-down system <NUM> is adapted for use in a wheelchair pan <NUM> of a rear entry vehicle for loading and restraining a wheelchair <NUM>,.

In particular, the two front tie-down units <NUM> and the two rear tie-down units <NUM> serve as a four-point wheelchair securement system for securing the wheelchair <NUM> in the vehicle. As described in more detail below, however, the front tie-down units <NUM> serve an additional function of winching the wheelchair <NUM> up and down the vehicle ramp <NUM> in a controlled and steerable manner. For the avoidance of doubt, it is contemplated that the novel features of the present system can be incorporated in systems that utilize more or less than four points of attachment to the wheelchair.

As shown in <FIG>, a first embodiment of the front tie-down units <NUM> comprises a motorized retractor that is capable of being independently controlled. The front tie-down units <NUM> may be essentially mirror images of each other, each comprising a ratcheted spool <NUM> for holding wound restraints <NUM>. An adjustable restraint sensor is provided to detect the amount of restraint <NUM> on the spool <NUM>. More particularly, in the disclosed embodiment, the restraint sensor includes a roller member <NUM> that rides on the surface of the restraint <NUM> to, in effect, sense the diameter of the restraint <NUM> that is coiled on the spool <NUM>. In the disclosed embodiment, the roller member <NUM> engages a contact switch <NUM> when the diameter of the restraint <NUM> on the spool <NUM> increases to a certain limit, whereby the controller <NUM> can react to disable the motors of the front tie-down units <NUM> and prevent damage to the passenger, wheelchair <NUM>, tie-down system <NUM>, and/or vehicle. See, in particular, <FIG>, where the roller member <NUM> is pushed by the restraint <NUM> into engagement with the contact switch <NUM>, and <FIG>, where the spool is empty and the roller member <NUM> is not engaged with contact switch <NUM>. Notably, the contact switch <NUM> is position adjustable using screw <NUM>, so the sensor limit can be set based on application-specific space constraints. It is contemplated, however, that other equivalent sensors can be used, including those that use optics or other sensor technology to determine the spool size. In addition, it is contemplated that a similar sensor could be used to determine when the wheelchair <NUM> is located in various positions within the application, such as in an optimal position in the vehicle, mid-way up the ramp <NUM> or located at the base of the ramp such as the street-level. This sensor could be used in combination with, or in the alternative to, a sensor designed to prevent damage or injury, as described above.

The ratcheted spool <NUM> is spring-biased by power spring assembly <NUM> to retract restraints <NUM>, and is powered in both rotational directions by a motor <NUM> through a speed-reducing gear and chain mechanism <NUM>. A locking pawl <NUM> is provided with a spring for engagement with the sprockets of the ratcheted spool <NUM>. In its default, spring-biased position (as shown in <FIG>), the locking pawl <NUM> engages with the ratcheted spool <NUM> and prevents the restraint <NUM> from being pulled out of the tie-down unit. However, the locking pawl <NUM> is movable via a release mechanism shown in <FIG> to an unlocked position whereby restraint <NUM> may be unwound from spool <NUM> and pulled out of the tie-down unit <NUM>. In substance, the release mechanism employs a nut <NUM> that traverses a portion of the length of a threaded shaft <NUM> powered by a gear motor <NUM>. At one end of its range, the nut <NUM> is configured to engage with and push the locking pawl <NUM> out of engagement with the ratcheted spool <NUM> until it triggers a first contact switch (or proximity switch or other equivalent sensor) <NUM> (See <FIG>). At the other end of its range, the nut <NUM> triggers a second contact switch (or proximity switch or other equivalent sensor) <NUM>, where the nut <NUM> is out of engagement with or otherwise allows the locking pawl <NUM> to engage with the sprocket of the ratcheted spool <NUM> (See <FIG>).

As shown in <FIG> and <FIG>, the restraint <NUM> is wound around the ratcheted spool <NUM> so that it leaves from the top of the spool. In addition, as shown in <FIG>, the ratcheted spool <NUM> is disposed at an end or side of the tie-down unit <NUM> opposite from the wheelchair <NUM>, whereby the motor <NUM> is disposed between the ratcheted spool <NUM> and the wheelchair <NUM>. The ratcheted spool <NUM> would be disposed at a rear end or side of the tie-down unit <NUM> (e.g., in an intended configuration, toward the front of the vehicle). As discussed in more detail in <CIT>, which is incorporated by reference, this configuration may provide space savings in a wheelchair securement system, where webbing ideally should extend between the retractor and the wheelchair at an angle of approximately <NUM>-<NUM>°, when compared to prior art systems that present webbing off of the bottom of the spool and present the spool at the front end or side of the tie-down unit that is closest/proximal to the wheelchair. The space savings achieved by the designs shown in <FIG> and <FIG> are best depicted in <FIG>. As shown specifically in <FIG>, by taking the webbing off of the top of the ratcheted spool <NUM>, rather than the bottom of the spool, the take-off point from the spool shifts to the trailing end of the spool (toward the front of the vehicle or at the point furthest from the wheelchair, in an intended configuration), rather than the leading end of the spool, and a space savings of approximately D<NUM> is realized. In other words, the size of the wheelchair securement area necessary to properly secure a wheelchair can be reduced by an approximate length of D<NUM> by taking the webbing off of the top of the ratcheted spool <NUM>, rather than off the bottom. In addition, as shown specifically in <FIG>, by disposing the motor <NUM> between the ratcheted spool <NUM> and the wheelchair <NUM>, where the ratcheted spool <NUM> is disposed at the rear end or side of the tie-down unit <NUM>, an additional space saving of approximately D<NUM> is realized. In other words, the size of the wheelchair securement area necessary to properly secure a wheelchair can be reduced by an approximate length of D<NUM> by positioning the ratcheted spool <NUM> at the rear end or side of the tie-down unit <NUM> opposite the wheelchair securement area.

Additionally, as specifically shown in <FIG> and <FIG>, space savings may be realized by the present embodiments by having two separate tie-down units <NUM>, as compared to prior art systems that utilize a single, centrally located, winch unit. The use of two, spaced apart units allows a wheelchair having foot rests to be pulled father forward in the securement area, as the footrest may enter the space separating the units. In contrast, this may not be possible with the prior art units, which would otherwise occupy the same space.

<FIG> show and describe embodiments of the control panel <NUM> and joystick <NUM>. The control panel <NUM> has buttons to switch system <NUM> modes and may provide a location for the joystick <NUM> to rest. The joystick <NUM> is used to control operation of the front tie-down units <NUM> and to maneuver (steer) the wheelchair <NUM> during loading and unloading. In general, the control panel <NUM> includes two buttons, the first button <NUM> being a lock or "final squeeze" button, and the second button <NUM> being an unlock or release button. The control panel <NUM> also includes one or more indication lights <NUM> that are reflective of the system condition or mode. In one embodiment, the control panel <NUM> could include LED indicators alerting users to loading (going up), unloading (going down), error codes (e.g., the pattern of flashing lights could indicate specific errors), and interlock (e.g., the unit could flash once the vehicle is safely moving to indicate that it is in a lock mode and joystick/operation is disabled). In another embodiment, the indication lights could be located on other structures in the vehicle. In yet another embodiment, the control panel <NUM> or other structure in the vehicle could include a reset switch to reboot the system <NUM> and reactivate normal operation (e.g., if an error code occurs). In yet another embodiment, the system <NUM> could be programmed where pushing all of the buttons on the control panel <NUM> at the same time will reset the system. The joystick <NUM> includes a dead-man (or trigger) button <NUM> (hidden on the opposite side of the joystick <NUM> in <FIG>) and a multi-axis controller, such as a thumbstick <NUM>, or other equivalent controls, such as a touchpad, arrow buttons, track ball, or wheels.

In one embodiment, the control panel <NUM> could serve as a backup for loading and unloading of the occupant, should the joystick <NUM> be lost or broken. To serve this purpose, the first and second buttons <NUM>, <NUM> could having combined functions, where they can be used for loading, unloading, final squeeze, initial release, and belt release. With such an arrangement, however, individual control of the two tie-down units <NUM> may not be possible. Both of the tie-down units <NUM> would be activated in the same direction simultaneously. To avoid this result, multiple, directional buttons (e.g., up, down, left, right) could be provided on the control panel <NUM> or other structure in the vehicle so that individual control of the two tie-down units <NUM>, and thus steering the occupant up/down the ramp <NUM>, will be possible, even in the event that the joystick <NUM> is lost or broken.

Referring now to <FIG>, the controller <NUM> is electrically connected to and in two-way communication with each of the two front tie-down units <NUM> and with the control panel <NUM> and joystick <NUM>. In the disclosed embodiment, the controller <NUM> is a programmable motor controller. In the preferred embodiment, the system <NUM> is programmed to have several modes: Idle, Release, Loading Wheelchair, Dock Wheelchair, Undock Wheelchair, Unloading Wheelchair, and Fault.

The Idle Mode is the default system condition. The system <NUM> is on and not in motion. The thumbstick <NUM> is in the center position and the dead-man button <NUM> is not engaged.

In the Release Mode, the wheelchair is at the bottom of the ramp and the controller <NUM> causes the restraints <NUM> to be released from the wheelchair, which allows the operator to withdraw the restraints <NUM> and wheelchair attachments <NUM> (e.g., hooks) from the front tie-down units <NUM> and secure them to the wheelchair <NUM>. The vehicle operator can place the system <NUM> in the Release Mode by pressing both buttons <NUM> and <NUM> simultaneously. In response to the button push, the controller <NUM> will cause the pawl release mechanism to push the pawl <NUM> out of engagement with the ratcheted spool <NUM> followed by activating the main motors <NUM> of the front tie-down units <NUM> in reverse for a predetermined amount of time. It has been found that <NUM> seconds is sufficient time for the restraints <NUM> to be withdrawn from the front tie-down units <NUM> and secured to the wheelchair <NUM>. After the predetermined amount of time has lapsed, the controller <NUM> stops the motors <NUM> and causes the pawl release mechanism to allow the pawl <NUM> to re-engage the ratcheted spool <NUM>. Release Mode can be aborted by moving the thumbstick forward (i.e., up, depending on perspective) for approximately <NUM> second, or by pressing buttons <NUM> or <NUM>, which returns the system <NUM> to the Idle Mode. In an alternative embodiment, the tie-down units <NUM> could be designed to have a full release, where the motors <NUM> would not need to be operated in reverse, which would allow the restraints <NUM> to be taken out quickly, rather than being limited to the speed of the motors <NUM>.

In the Loading Mode, the controller <NUM> causes the front tie-down units <NUM> to pull the wheelchair up the ramp <NUM> of the vehicle. The operator places the system <NUM> in the Loading Mode by pressing and holding the dead-man button <NUM> and adjusting the thumbstick <NUM> forward (up) on the joystick. In response, the controller <NUM> will cause the locking pawls <NUM> to engage with the ratcheted spool <NUM> (if not engaged already). The controller will also engage the motors <NUM> of the front tie-down units <NUM> to pull the wheelchair up the ramp <NUM> of the vehicle. The speed of the motors will be adjusted depending upon how far forward the thumbstick <NUM> is pushed (the farther the thumbstick is pushed forward from center, the faster the motors will be operated and the faster the wheelchair <NUM> will be pulled up the ramp). During loading, the operator can make left corrections to the wheelchair <NUM> path by continuing to push the thumbstick <NUM> forward and slowly adjusting the thumbstick <NUM> to the left to correct steering as necessary. In response, the controller <NUM> will keep the pawls <NUM> locked and independently adjust the speeds of the left and right motor <NUM> to help steer while pulling the wheelchair up the ramp. Typically, this will involve slowing down the left motor, increasing the speed of the right motor, or both. The differential in speed between the motors will depend upon how far left the thumbstick <NUM> is pushed (the further left it is pushed, the larger the differential and the tighter the turn). Right corrections to the wheelchair can be made in a similar manner by continuing to push the thumbstick <NUM> forward and slowly adjusting the thumbstick <NUM> to the right. In response, the controller <NUM> will decrease the speed of the right motor, increase the speed of the left motor, or both. If the dead-man button <NUM> or the thumbstick <NUM> is released while loading, the controller <NUM> causes the motors to stop turning and the system enters the Idle Mode. Since the pawls <NUM> are already in the "lock" position, the wheelchair <NUM> will not roll backwards down the ramp <NUM>. Note, however, that it is envisioned that the controller <NUM> could be programmed to require that the dead-man button <NUM> only be depressed and released for the system to enter the Loading Mode, as opposed being held depressed during the entire operation. In this case, releasing the dead-man button <NUM> will not cause the system to enter the Idle Mode.

When pressing forward or backwards on the thumbstick <NUM>, there may be a momentary lag (e.g., around <NUM> seconds) before the wheelchair <NUM> moves. To serve as a safety warning, the system <NUM> can be provided with an audible and/or visual prompt (for example, a buzzer, beeping sound or flashing light) in these momentary sequences to let the operator and wheelchair passenger know that something is about to happen.

As mentioned above, in the first embodiment of the system <NUM>, the pawls <NUM> will be engaged with the ratcheted spool <NUM> (if not engaged already) in the Loading Mode. When the wheelchair <NUM> is being pulled up the ramp <NUM>, the tie-down units <NUM> will make a "clang-clang-clang" noise as the pawls <NUM> disengage and reengage with the teeth of the ratcheted spool <NUM>, similar to the sound a roller coaster makes as it goes up a peak just before the drop. In one alternative embodiment, the controller <NUM> can eliminate the noise by actuating the pawl <NUM> slightly so that it is moved just past the teeth of the ratcheted spool <NUM>, and therefore can be quickly put back into engagement with the ratcheted spool <NUM> when the system enters the Idle Mode.

In the Dock Mode, the wheelchair is inside the vehicle, the rear restraints <NUM> are in place, and the wheelchair is secure. To enter the Dock Mode, the operator pushes lock button <NUM>. In response, the controller <NUM> causes the motors <NUM> to do one last short pull, whereby the spool <NUM> rotates in a forward direction to apply one last pull (referred to as "final squeeze") to tension or stretch the restraints <NUM>, <NUM> and properly lock and secure the wheelchair <NUM> in the system <NUM>. In the preferred embodiment, the controller <NUM> monitors the current being provided to the motors <NUM> to confirm adequate system tightness. As an alternative to monitoring current, it is contemplated that the controller <NUM> could alternatively be programmed to operate the motor for a predetermined period of time to confirm tightness.

In the Undock Mode, the wheelchair is inside the vehicle and the rear restraints <NUM> are in place. However, the system is "loose" whereby the rear restraints <NUM> can be removed. To enter the Undock Mode, the operator pushes the unlock button <NUM>. In response, the controller <NUM> will cause the main motors <NUM> to operate in a forward direction for a short period of time to release pressure between the pawl <NUM> and spool <NUM> (to allow a soft unload process to start). Thereafter, the controller <NUM> will unlock the pawls <NUM>, operate the motors <NUM> in reverse for a short period of time to loosen the system <NUM>, and then re-lock the pawls <NUM>. At this point in time, the system <NUM> is loose and the rear restraints <NUM> can be removed easily.

In the Unloading Wheelchair Mode, the controller <NUM> causes the front tie-down units <NUM> to operate in reverse, whereby the weight of the wheelchair pulls the wheelchair <NUM> down the ramp <NUM> of the vehicle. The operator places the system <NUM> in the Unloading Mode by pressing and holding the dead-man button <NUM> and adjusting the thumbstick <NUM> backward (down) on the joystick. In response, the controller <NUM> will cause the main motors <NUM> to operate in a forward direction for a short period of time to release pressure between the pawl <NUM> and spool <NUM> (to allow a soft unload process to start). Thereafter, the controller <NUM> will unlock the pawls <NUM> and operate the motors <NUM> in reverse. As with the forward direction, the speed of the wheelchair <NUM> depends upon how far the thumbstick <NUM> is pushed downward away from center. The operator can make left and right corrections to the positioning/direction of the wheelchair by continuing to hold the thumbstick <NUM> backward while slowly adjusting it to the left or right, as necessary. In response, the controller <NUM> will make appropriate corrections to the speed of the left and right motors <NUM>. For example, if a left correction is made, the controller <NUM> will increase the speed of the right motor, decrease the speed of the left motor, or both, which will alter the direction and path of the wheelchair. Similarly, if a right correction is made, the controller <NUM> will increase the speed of the left motor, decrease the speed of the right motor, or both. As with turns in the forward direction, described above, the motor speed differential and tightness of the turn when operating in reverse will depend upon how far left or right the thumbstick <NUM> is pushed from center. If while unloading the user releases the dead-man button <NUM> or the thumbstick <NUM>, the system will enter the Idle Mode. The controller <NUM> will cause the motors <NUM> to stop and will lock the pawls <NUM>. As noted above, however, it is envisioned that the controller <NUM> could be programmed to require that the dead-man button <NUM> only be depressed and released for the system to enter the Unloading Mode, as opposed being held depressed during the entire operation. In this case, releasing the dead-man button <NUM> will not cause the system to enter the Idle Mode. If necessary to prevent jerking the wheelchair passenger during entry into Idle mode, the controller <NUM> will lock the pawls <NUM> and cause the motors <NUM> to operate in a forward direction to prevent fast descent of the wheelchair <NUM> down the ramp <NUM>. Once off the ramp, the restraints <NUM> can be removed from the wheelchair and walked back to the front tie-down units <NUM> or placed on the storage bracket (<NUM>). The clutch in the front tie-down units <NUM> will be loose, allowing the restraints to recoil without using the motors <NUM>.

The controller <NUM> may be provided with a vehicle interlock, whereby the controller <NUM> is provided with an indication of whether the vehicle status is safe for operating the system <NUM> (for example, whether the vehicle ignition is engaged, the ramp is down, and/or the vehicle is in park). If the vehicle status is not safe, the controller <NUM> can prevent operation of the system <NUM>.

<FIG> show generally how the tie-down system <NUM> is used. Once the vehicle is in a parked position with the ramp <NUM> lowered, the operator will simultaneously press both buttons <NUM>, <NUM> on the control panel <NUM>, which will place the tie-down units <NUM> in the Release Mode. When placed in the release mode, the operator is able to pull the restraints <NUM> out of the tie-down units <NUM> and place the attachments <NUM> on the front of wheelchair <NUM> frame which is already placed in front of the ramp <NUM>, as shown in <FIG>.

At this point, the operator will use the joystick <NUM> to control the movement and speed of the wheelchair forward, backward, left and right. In particular, the driver will press the dead-man button <NUM> with his or her index finger, which activates the thumbstick <NUM>, while using his or her thumb on the thumbstick <NUM> to directionally control the wheelchair <NUM>. Once the wheelchair is inside of vehicle, the operator proceeds to secure wheelchair restraints <NUM> of the rear tie-down units <NUM> to the rear of the wheelchair <NUM> frame.

The operator then pushes the lock button <NUM> which cause the front tie-down units <NUM> to take the slack out of the system <NUM> and/or tension the restraints <NUM>, <NUM> and secure the wheelchair <NUM> (referred to as the "final squeeze"). After the wheelchair <NUM> is secured, the operator will secure the wheelchair passenger using an occupant restraint system <NUM>. The wheelchair <NUM> and wheelchair passenger are shown fully secured in the vehicle in <FIG>.

To unload the wheelchair <NUM>, once the vehicle is in park and the ramp <NUM> is down, the operator removes the occupant restraint system <NUM> and presses the unlock button <NUM> on the control panel <NUM>. The tension in the system will be released, allowing the operator to remove the restraints <NUM> of rear tie-down units from the wheelchair <NUM> frame and store them. Using the joystick <NUM>, as described in more detail above, the wheelchair <NUM> can be unloaded from the vehicle, down the ramp <NUM>, in a controlled manner.

There are several key features and benefits of the present embodiment, as compared to the prior art:.

Referring now to <FIG>, a second embodiment of a tie-down unit <NUM> is depicted, the internal structure of which is similar to the first embodiment of the tie-down unit <NUM>, but with certain new aspects, some of which are more particularly described in <CIT>, For instance, the tie-down unit <NUM> is provided with a webbing guide <NUM> that rotates around at least a portion of the circumference of the retractor spool (not shown). The tie-down unit <NUM> may also be provided with a sliding webbing shield <NUM> that follows the travel of the webbing guide <NUM> to prevent ingress of debris or fluids into the housing of the tie-down unit <NUM>. As shown in <FIG>, a third embodiment of a tie-down unit <NUM> is depicted. The third embodiment is substantially the same as the second embodiment, but instead of the webbing shield <NUM>, includes a flap <NUM> that is fixed at the top of the opening to the housing of the tie-down unit <NUM> and extends over the restraint and webbing guide to prevent ingress of debris and fluids. As shown in <FIG>, a fourth embodiment of a tie-down unit <NUM> is depicted. The fourth embodiment is substantially the same as the second and third embodiments, except it includes brushes or other flexible members <NUM> on one or more of the edges of the opening of the housing to prevent the ingress of debris and fluids. In alternative embodiments, some combination of the webbing shield <NUM>, flap <NUM>, and/or brushes <NUM> could be used to prevent ingress of debris and fluids.

As shown in <FIG>, a fifth embodiment of the tie-down unit <NUM> may include features enabling the unit <NUM> to be removed and swapped out easily, such as a wire harness door <NUM> that may be opened to allow easy disconnection of the wiring harness <NUM>. The unit <NUM> may also include a quick release bracket <NUM> extending externally from the housing of the unit <NUM>, so that the unit <NUM> may be easily disconnected and connected to a vehicle.

As shown in <FIG>, additional embodiments of the tie-down unit may include a swivel bracket <NUM> that is connected between the tie-down unit and the vehicle. The swivel bracket <NUM> permits the tie-down units to pivot and align itself with the direction of the pull/load path.

As shown in <FIG>, other embodiments may include a hook storage member <NUM> that may include a loop <NUM> that serves to store/secure the hook <NUM> at the end of the restraint <NUM> to a vehicle surface. In some embodiments, the loop <NUM> may comprise a fabric, webbing, or other "soft" material to allow for securement with minimal or reduced noise (i.e., metal on metal, vibrations and movements from vehicle, etc.). The hook storage member <NUM> could be disposed toward the wheelchair entry point into the vehicle, such as the rear of the vehicle or toward the rear of the wheelchair pan <NUM> that supports the wheelchair, for easier access by the operator of the vehicle. The hook storage member <NUM> may prevent damage to the tie-down unit and/or the vehicle if the tie-down unit is accidentally activated while the hook <NUM> is in storage (e.g., it will rip the loop <NUM> out, and not rip the wall or damage the tie-down unit). The hook storage member <NUM> could be designed to take a predetermined amount of force, for example by using loops <NUM> of different strength/thickness, or by design of stronger/additional fasteners.

As shown in <FIG>, a retrofit bracket <NUM> could be used that allows an existing electric retractor to be retrofitted to a tie-down unit disclosed herein. The retrofit bracket <NUM> would include a pattern of apertures that corresponds to both the existing electric retractor and the replacement tie-down unit.

The tie-down system may include various sensors that provide signals to the controller <NUM> concerning the location of the wheelchair during a loading or unloading operation. For instance, sensors may be incorporated into the hook end of the restraints to provide an indication to the controller that the restraints are reaching the maximum pull distance. For example, wireless positioning sensors with XYZ coorinates, including systems that make use of various optical, radio, or acoustic technologies, could be used. The sensors in the hook end restraints could also provide an indication of the location of the wheelchair throughout the entire loading and unloading operation. Trilateration (<NUM> points) is ideal as it would provide an indication of absolute positioning, but the vertical component is not essential for this application. As shown in <FIG>, sensors in the form of light curtains <NUM> could be incorporated, where the light curtains <NUM> would be disposed longitudinally on or near the edges of one or both the wheelchair pan <NUM> and the ramp <NUM> to detect when the wheelchair <NUM> is approaching or about to go off an edge of the wheelchair pan <NUM> or ramp <NUM>. The light curtains could also be disposed laterally anywhere along the travel path of the wheelchair, for example, at the bottom of the ramp, at the rear or front end of the wheelchair pan, and/or multiple locations there between. In addition, as shown in <FIG>, ramp imbedded pressure sensors or switches <NUM>, <NUM> could be provided on the wheelchair pan <NUM> and/or the ramp <NUM> to provide an indication of the location of the wheelchair. Multiple pressure sensor strips could be used, including longitudinally extending strips <NUM> at or near the edges of the wheelchair pan <NUM> and/or the ramp <NUM>, to provide an indication that the wheelchair <NUM> is veering off center. In addition, or in the alternative, multiple, laterally extending pressure sensor strips <NUM> could be provided on the wheelchair pan <NUM> and/or the ramp <NUM>, to provide an indication of where the wheelchair is, longitudinally, during the loading and unloading process. In the alternative, a solid surface pressure sensor could be used on one or both of the wheelchair pan <NUM> and the ramp <NUM> to provide an indication of both the lateral and longitudinal location of the wheelchair during the loading and unloading process. Other sensors providing an indication of the location of the wheelchair could be used, such as IR, ultrasonic, optical or video/camera systems, capacitive sensors, laser distance measuring, magnetic resonance. In addition, the restraint sensor <NUM> or various encoders described above could also be used.

Any combination of the sensors described herein could provide an indication of the position, direction, and speed of the wheelchair to the controller <NUM>, whereby that information would be used by the controller <NUM> to automate the loading/unloading process and/or to prevent damage to the wheelchair or occupant. For instance, the controller <NUM> could be programmed to stop a loading or unloading operation or automatically turn a wheelchair away from an edge of the ramp <NUM> or wheelchair pan <NUM> and redirect it to the center during a loading or unloading operation (by means provided above, by accelerating one of the tie-down units, decelerating the other of the tie-down units, or both), should a sensor provide an indication that the wheelchair is approaching or at such an edge. The controller <NUM> could also be programmed to stop a loading operation when the wheelchair is properly positioned for final securement in the wheelchair pan <NUM>, or could stop an unloading operation when the wheelchair leaves the ramp <NUM>.

Claim 1:
A wheelchair accessible vehicle comprising a wheelchair securement system (<NUM>) for securing a wheelchair (<NUM>) in a wheelchair securement area (<NUM>), characterized in that the wheelchair accessible vehicle further comprises:
a sensor (<NUM>, <NUM>, <NUM>, <NUM>) configured to detect at least one of a location, a direction, and a speed of the wheelchair (<NUM>) during at least one of a loading operation and an unloading operation of the wheelchair (<NUM>) into the wheelchair securement area (<NUM>); and
a controller (<NUM>) configured to communicate with the wheelchair securement system and configured to receive a signal from the sensor (<NUM>, <NUM>, <NUM>, <NUM>), wherein the signal is indicative of at least one of the location, the direction and the speed of the wheelchair (<NUM>).