Patent Publication Number: US-11654062-B2

Title: Wheelchair harness

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 63/111,726, filed on Nov. 10, 2020, the contents of which are herein incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present disclosure generally relate to an assistive movement device; and more specifically to posture assistance devices to aid user mobility. 
     BACKGROUND 
     Some users have conditions in which they are often unable to move to a desired postural position. Sometimes this may be caused by medical conditions such as, for example multiple sclerosis. Sometimes users experience such conditions long term; other times such conditions are temporary. 
     SUMMARY 
     The disclosure describes posture assistance devices, which according to some embodiments include a motor coupled to a frame. The frame can be attached to a wheelchair and a shaft can be coupled to the motor, where the motor is configured to rotate the shaft. An extension arm can be attached to the frame, where the extension arm includes a redirection surface. The extension arm can be selectively adjustable to change a distance between the redirection surface and the shaft. The device can include a connection line coupled to the shaft and configured to engage with the redirection surface, such that rotation of the shaft changes a length a fed-out portion of the connection line. The device can include an attachment mechanism configured to couple the connection line to a user. 
     In some embodiments, the extension arm includes an adjustable rail, the redirection surface being disposed on the adjustable rail. 
     In some embodiments, the extension arm includes an attachment rail and an adjustable rail, the attachment rail being attached to the frame, and the adjustable rail being selectively adjustable with respect to the attachment rail. 
     In some embodiments, the attachment rail includes multiple first holes each configured to receive a pin, and the adjustable rail comprises multiple second holes each configured to receive the pin, the pin being insertable simultaneously in one of first holes and one of the second holes. 
     In some embodiments the pin is a first pin, and a second pin is insertable simultaneously in a second of the plurality of first holes and a second of the plurality of second holes to create a fixed relationship between the attachment rail and the adjustable rail. 
     In some embodiments, the frame is configured to be attached to a back of the wheelchair. 
     In some embodiments, the redirection surface is a surface of a roller wheel. 
     In some embodiments, the connection line is a belt. 
     In some embodiments, the belt includes a first belt segment and a second belt segment, wherein the belt further comprises hook and loop fasteners attaching the first belt segment to the second belt segment. 
     In some embodiments, the device includes a ratchet wheel and a pawl, the ratchet wheel being coupled to the shaft, and the pawl being configured to selectively engage with the ratchet wheel. 
     In some embodiments, the extension arm is a first extension arm, and the connection line is a first connection line, wherein the posture assistance device further comprises a second extension arm and a second restrainer line. 
     The disclosure describes posture assistance devices, which according to some embodiments include a motor coupled to a frame. The frame can be attached to a wheelchair and a shaft can be coupled to the motor, where the motor is configured to rotate the shaft. An extension arm can be attached to the frame, where the extension arm includes a redirection surface. The extension arm can be selectively adjustable to change a distance between the redirection surface and the shaft. The device can include a connection line coupled to the shaft and configured to engage with the redirection surface, such that rotation of the shaft changes a length a fed-out portion of the connection line. The device can include an attachment mechanism configured to couple the connection line to a user. The device can also include a controller, where the controller is configured to receive a motor speed signal representing a speed of the motor. In some embodiments, the controller is configured to operate in a lifting mode, wherein in the lifting mode, the controller is configured to send a drive signal to the motor, the drive signal being based on a comparison between the speed of the motor and a reference speed. 
     In some embodiments, the controller is configured to operate in the lifting mode in response to a first user command, wherein in the lifting mode the torque signal causes the motor to rotate in a first direction that causes the length of the fed out portion of the connection line to decrease. 
     In some embodiments, the controller is configured to operate in a lowering mode in response to a second user command, wherein in the lowering mode the torque signal causes the motor to rotate in a second direction that causes the length of the fed out portion of the connection line to increase. 
     In some embodiments, a Hall effect sensor is in a fixed relationship with the frame, the Hall effect sensor being configured to send a proximity signal to the controller when a magnet is in proximity to the Hall effect sensor. 
     In some embodiments, the magnet is fixed to the connection line at a predetermined location. 
     In some embodiments, the controller is configured to operate in a stop mode in response to receiving the proximity signal from the hall effects sensor, wherein the controller is further configured to operate in the stop mode in response to receiving a stop command from the user. 
     Some embodiments include a ratchet wheel coupled to the shaft, wherein, when the controller is operating in the stop mode, the controller is configured to actuate a pawl to engage with the ratchet wheel to maintain the shaft in a static position. 
     In some embodiments, the extension arm includes an adjustable rail, the redirection surface being disposed on the adjustable rail. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a posture assistance device mounted to the back of a chair, according to one embodiment. 
         FIGS.  2 A and  2 B  show user operation of the posture assistance device of  FIG.  1   . 
         FIGS.  3  and  4    show alternate arrangements of the posture assistance device of  FIG.  1   . 
         FIG.  5    shows the posture assistance device of  FIG.  1    mounted to the bottom of the chair. 
         FIGS.  6  and  7    show the external views of the posture assistance device of  FIG.  1   . 
         FIG.  8    shows a mounting structure for the posture assistance device of  FIG.  1    according to some embodiments. 
         FIGS.  9  and  10    show another mounting structure for the posture assistance device of  FIG.  1    according some embodiments. 
         FIG.  11 - 12 C  show another mounting structure for the posture assistance device of  FIG.  1    according some embodiments. 
         FIGS.  13  and  14    show internal views of the posture assistance device of  FIG.  1   . 
         FIG.  15    shows an extension arm of the posture assistance device of  FIG.  1   . 
         FIG.  16    shows a detailed internal view of the posture assistance device of  FIG.  1     
         FIG.  17    shows a connection line of the posture assistance device of  FIG.  1   , according to one embodiment. 
         FIG.  18    shows a connection line of the posture assistance device of  FIG.  1   , according to one embodiment. 
         FIG.  19    shows the electrical system of the posture assistance device of  FIG.  1   . 
         FIG.  20    shows the remote control board of the posture assistance device of  FIG.  1     
         FIG.  21    shows a control scheme for the posture assistance device of  FIG.  1     
         FIG.  22    shows the state machine for the posture assistance device of  FIG.  1     
         FIGS.  23 - 25    show a posture assistance device according to one embodiment. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. 
     While the disclosure is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG.  1    shows a posture assistance device  100  according to an embodiment of the present disclosure. Device  100  can be mounted and adjusted to various chairs, including wheel chairs, in order to facilitate posture adjustments. Device  100  can include a control system that responds to user commands and adjusts operation of the device  100  depending on the user&#39;s strength. 
       FIG.  1    shows device  100  coupled to the back  12  of a seat  1  according to one embodiment. The device  100  is coupled to a chair frame  20  of the chair  1 . Device  100  is configured to raise, lower, and/or support the torso of a user sitting in the chair  1 . This is accomplished using connection lines  5 , which are coupled to the user via an attachment mechanism  7 . In some modes of operation, the length of a fed-out portion of the connection lines  5  (fed-out from device  100 ) is adjusted to raise or lower a torso of the user seated in the chair  1 . In other modes of operation, the length of a fed-out portion remains constant to support the user in a desired position. Device  100  includes cover  135 , according to some embodiments. Device  100  further includes one or more extension arms  140  and a roller wheel  150  disposed on each extension arm  140 . The roller wheel  150  redirects the connection line  5  toward a user sitting in the chair  1 . 
     As used herein, the term “coupled” is used in its broadest sense to refer to elements which are connected, attached, and/or engaged, either directly or integrally or indirectly via other elements, and either permanently, temporarily, or removably. 
     In the embodiment shown in  FIG.  1   , chair  1  is a wheelchair, with the wheels omitted for clarity. In some embodiments, the chair  1  is a wheel chair. In other embodiments, the chair  1  is a stationary chair, a hospital bed, or any item of furniture used for sitting.  FIG.  1    shows two connection lines  5 ; some embodiments include one connection line  5 , or more than two connection lines  5 . In some embodiments, the connection line  5  is a belt. In other embodiments the connection line is a cable, rope, cord, and/or strap.  FIG.  18    illustrates an alternative connection line  5 A,  5 B, according to some embodiments. 
       FIGS.  2 A and  2 B  show the use of device  100  according to one embodiment.  FIGS.  2 A and  2 B  are side views with a cutaway views of the device  100  without the cover  135 . A vest  2  worn by the user  3  is coupled to the connection line  5 ; for example, connection line  5  may couple to vest  2  (or other garment, harness, strap, pad, undergarment, and/or the like) at an area above the waist of the user, and/or above the chest of the user, and/or above the shoulder of the user, and/or at a top of the user&#39;s torso, according to some embodiments of the present disclosure. In  FIG.  2 A , the user  3  is in a “down” position. If the user  3  desires assistance to sit upright, he or she may give a raising command to the device  100  indicating a desire to be lifted up. The user  3  may give the raising command by pushing a button or using a voice command (for example, as discussed in greater detail in relation to  FIGS.  13 - 16   ). In response to the command, the device  100  shortens a length of the fed-out portion of the connection line  5 , to lift the user to the upright position shown in  FIG.  2 B . 
     A user  3  in the upright position shown in  FIG.  2 B  might desire to be let down. In this case, the user  3  may give a lowering command to the device  100  indicating a desire to be let down. The user  3  gives the lowering command by pushing a button or by giving a voice command (for example, as discussed in greater detail in relation to  FIGS.  13 - 16   ). In response to this command, the device  100  lengthens a portion of the fed-out portion of the connection line  5 , to let the user down to the position shown in  FIG.  2 A  and to give the user sufficient slack to move freely, according to one embodiment. 
     While the user  3  is being raised or lowered, the user  3  may give a stop command indicating a desire for the device  100  to stop raising or lowering the user and for the connection line  5  to be locked in place, according to some embodiments. 
       FIG.  3    shows device  100  with the extension arms  140  in an extended position as compared to the position of the extension arms  140  in  FIG.  1   . In some embodiments, the length of the extension arms  140  are adjustable to accommodate a specific chair or wheelchair. The length of the extension arms  140  affects the angle at which the connection line  5  raises the user. The extension arms  140  are adjustable so that the connection line  5  may raise the user at an angle of optimal comfort and lifting assistance. Increasing the length of the extension arms  140  increases the angle at which the connection line  5  lifts the user, while decreasing the length of the extension arms  140  decreases the angle at which the connection line  5  lifts the user. An optimal angle of the connection line  5  allows the user&#39;s torso to naturally and comfortably rotate from the down position (see  FIG.  2 A ) to the upright position (see  FIG.  2 B ). The optimal angle of the connection line  5  may be achieved for each user by adjusting the length of the extension arms  140 . The length of the extension arms  140  that achieves the optimal angle of the connection line  5  may differ based on various factors such as the height of the user, the model of the chair  1 , and the position of the device  100  with respect to the chair  1 . The adjustable nature of the extension arms  140  thus allows an optimal angle of the connection line  5  to be achieved in a variety of different circumstances. The extension arms  140  are described in greater detail in relation to  FIGS.  14  and  15   . 
       FIG.  4    shows device  100  mounted at a higher position with respect to the chair  1  as compared to the position of device  100  in  FIG.  1   . The attachment mechanism (described in greater detail in relation to  FIGS.  7 - 12 C ) allows the device  100  to be mounted at various vertical positions on the back  12  of the chair  1 . 
       FIG.  5    shows device  100  mounted to a bottom  11  of the chair  1 .  FIG.  5    is a side view of the chair  1  with a cutaway view of the device  100  without the cover  135 . In this arrangement, a mounted set of roller wheels  151  is mounted to the chair  1  on upper frames  152 . The mounted set of roller wheels  151  directs the connection line  5  from the device roller wheels  150  to the user in the chair  1 . The device  100  may be adjusted in a forward/backward direction with respect to the chair  1  with the attachment mechanism (described in greater detail in relation to  FIGS.  7 - 12 C ). In some cases, a hair shield  8  is attached one or more upper frames  152  to discourage the user&#39;s hair from being caught in the mounted roller wheels  151 . Connection line  5  may pass through a slot in the hair shield  8 , according to some embodiments. 
       FIG.  6    shows a top, front perspective view of device  100  according to some embodiments. Cover  135  includes an outer cover  137  and an inner cover  136 . Cover  135 , encloses, covers, and/or surrounds mechanical components (shown in more detail in  FIGS.  13  and  14   ) of the device  100 . Outer cover  137  includes a body outer cover  137 A that encloses the motor  110  (see  FIGS.  13  and  14   ), and arm outer covers  137 B that each enclose a portion of a respective extension arm  140  (see  FIGS.  4  and  5   ) according to some embodiments. In some embodiments, outer cover  137  is all or partially plastic. In other embodiments, outer cover  137  is all or partially any other light material. A roller wheel  150  is coupled to each extension arm  140 . The surface  150 A of each roller wheel  150  is a redirection surface operable to redirect the connection line  5 . 
       FIG.  7    shows a bottom, back perspective view of device  100 . The inner cover  136  encloses the device  100  on the side facing the seat  1  (see  FIG.  1   ). The inner cover  136  includes a body inner cover  136 A that encloses the motor  110  (see  FIGS.  4  and  5   ), and arm inner covers  136 B that each enclose a portion of a respective extension arm  140  (see  FIGS.  4  and  5   ). The inner cover  136 , is configured to engage with the outer cover  137  to enclose the motor  110  and other components. In one embodiment, the inner cover  136  is plastic. In other embodiments, the inner cover  136 A,  136 B may be any other light material. 
     In one embodiment, one or more tracks  175  are attached to cover  135 . For example, two tracks  175  may be attached to an outside of the body inner cover  136 A. The tracks  175  may be affixed to a bottom plate  131  of frame  130  ( FIG.  14   ), for example via a screw or bolt attachment through the main inner cover  136 A (as shown in  FIG.  14   ) for structural support, with the main inner cover  136 A sandwiched between the tracks  175  and the bottom plate  131 , according to some embodiments. Cross members  181 , which in some cases may be tubes, are mounted onto the tracks  175  with one or more mounting members  180 , which in some cases may be mounting feet. The mounting members  180  are secured to the tracks  175 , for example with T-nuts, bolts, screws, or other attachment components. Each cross member  181  may be positioned at various vertical locations along the length of the tracks  175 , giving the device  100  adaptability to be connected to the back or bottom of a variety of different models of chairs and wheel chairs. In one embodiment, the cross members  181  are aluminum. However, the cross members  181  may be any material or shape capable of providing the required structural support for mounting the device  100 . While  FIG.  7    shows two cross members  181 , in some embodiments the device  100  may include more than two cross members  181  or, alternatively, the device  100  may include only one cross member  181 , depending on the requirements for mounting the device  100  to a specific model chair or wheel chair. 
     The variable position of the mounting members  180  with respect to the tracks  175  allows the device  100  to be adjusted vertically with respect to the back of the chair  1 . For example,  FIG.  4    shows a device  100  mounted in a higher vertical position with respect to the chair  1 , as compared to the position the device  100  in  FIG.  1   . 
     When the device  100  is mounted on the bottom of the chair  1 , as shown in  FIG.  5   , the variable position of the mounting member  180  with respect to the tracks  175  allows the device to be adjusted forward and backward with respect to the bottom of the chair  1 . 
     The arrangement of tracks  175  and cross members  181  as shown in  FIG.  7    may be used in conjunction with a variety of mounting arrangements, at least three of which are discussed below. However, the arrangement of tracks  175  and cross members  181  may be used in conjunction with other mounting arrangements. 
       FIG.  8    shows one possible mounting arrangement. A shaft collar  51  may be secured at any desired position along the cross member  181 . The shaft collar  51  is secured to the cross member  181 . In one example, the shaft collar  51  is secured to the cross member  181  by tightening a screw  52 . A frame collar  53  is secured to the shaft collar  51 . In some embodiments, the frame collar  53  is secured to the shaft collar  51  with a connecting screw  55 , or alternatively with a bolt or another fastener. The frame collar  53  may be secured at any suitable angle with respect to the shaft collar  51  to engage with the frame of the chair  1 . The frame collar  53  is secured to the frame of the chair (for example chair frame  20  shown in  FIG.  1   ). In one example, the frame collar  53  is secured to the frame of the chair by tightening a screw  54 . The frame collar  53  may have a diameter that is the same or different from the shaft collar  51 , depending on the diameter of the frame of the chair, according to some embodiments. 
     Multiple sets of shaft collars  51  and frame collars  53  may be used to mount the device  100  to the chair  1 . 
       FIGS.  9  and  10    show an additional and/or alternative mounting arrangement, according to some embodiments. A shaft collar  61  may be secured at any desired position along the cross member  181 . The shaft collar  61  is secured to the cross member  181 . In one example, the shaft collar  61  is secured to the cross member  181  by tightening a screw  62 . A bracket  63  is coupled to the shaft collar  61 . In some embodiments, the bracket  63  is affixed to the shaft collar  61  with a screw, or a bolt, or another fastener. The bracket  63  may be mounted in any rotational position relative to the shaft collar  61 . A strap  64  passes through the bracket  63 . A buckle  65  on the strap  64  allows the strap  64  to be tightened around one or more parts of a wheelchair frame by passing an end  66  of the strap  64  through the buckle  65 . This mounting arrangement can mount device  100  to wheelchairs that have difficult-to-reach attachment points, for example. 
     In one embodiment, the strap  64  is fabric. In other embodiments, the strap  64  is rubber, polymer, nylon, string, rope, braided textile, woven textile, cord, chain, and/or any strong, flexible material. 
       FIGS.  11  and  12 A- 12 C  show yet another alternative mounting arrangement of device  100 , according to some embodiments. A shaft collar  71  may be secured at any desired position along the cross member  181 . The shaft collar  71  is secured to the cross member  181 . In one example, the shaft collar  71  is secured to the cross member  181  by tightening a screw  72 . A hook  73  is coupled to the shaft collar  71 . In some embodiments, the hook  73  is affixed to the shaft collar  71  with a screw, or a bolt, or another fastener. The hook  73  engages with a cylindrical element  75  on a bracket  74 , such that the cylindrical element  75  bears weight from the device  100 . The bracket  75  is coupled to a mounting collar  76 . In some embodiments, the bracket  75  is affixed to the mounting collar  76  with a screw, or a bolt, or another fastener. The mounting collar  76  is secured to a chair frame (for example, the chair frame  20  in  FIG.  1   ). The hook  73  and the bracket  74  may be aluminum or any suitable material capable of bearing a structural load. 
       FIG.  12 A  shows a separated view of the hook  73  and bracket  74 .  FIG.  12 B  shows a view in which the hook  73  is engaged with a horizontal bracket  74 .  FIG.  12 C  shows a view in which the hook  73  is engaged with a vertical bracket  74 . 
     The collars  51 ,  53 ,  61 ,  71 ,  76 , may be split collars each having two halves that may be screwed together to tighten around a cross member  181  or the chair frame. 
     Any combination of the mounting arrangements described above may be used to mount the device  100  to the chair  1 . The use of the rails  175  and cross members  181  in conjunction with different mounting arrangements allows the device  100  to be mounted to a variety of commercial chairs and wheelchairs. 
       FIG.  13    shows an internal view of device  100  according to one embodiment. The motor  110  is coupled to a gearbox  115 , which drives the motor shaft  116 . A timing belt  120  transmits torque from the motor shaft  116  to a belt shaft  125 . In one embodiment the timing belt  120  has a 1:1 gear ratio from the motor shaft  116  to the belt shaft  125 . In some embodiments, the timing belt may have a 1:2 ratio or any other ratio that achieves an appropriate torque for the belt shaft  125 . Some embodiments include alternate arrangements for transmitting torque from the motor shaft  116  to the belt shaft  125 . For example, one or more gears may couple the motor shaft  116  to the belt shaft  125 . In other embodiments, the belt shaft  125  has the same rotational axis as the motor  110  and the motor  110  or gearbox  115  directly rotates the belt shaft  125 . 
     Each connection line  5  is coupled to the belt shaft  125 . Rotation of the belt shaft  125  in a clockwise direction decreases the length of the fed-out portion of the connection line  5 , and rotation of the belt shaft  125  in a counter-clockwise direction increases the length of the fed-out portion of the connection line  5 . Other embodiments use the reverse arrangement such that the rotation of the belt shaft  125  in a clockwise direction increases the length of the fed-out portion of the connection line  5 , and rotation of the belt shaft  125  in a counter-clockwise direction decreases the length of the fed-out portion of the connection line  5 . 
     The belt shaft  125  may have clamps to secure the end of each connection line  5  to the belt shaft  125 . Alternatively, there may be slots in the belt shaft  125  such that the end of the connection line  5  may pass through the slot, loop around a portion of the belt shaft,  125 , and be sewn to an adjacent portion of the connection line  5 . The connection line  5  may also be secured to the belt shaft  125  by any other suitable arrangement ensuring that the connection line  5  remains coupled to the belt shaft  125  during rotation of the belt shaft  125 . 
     In an alternate embodiment, the motor and/or gearbox  115  may directly rotate the belt shaft  125 . 
     The device  100  includes frame  130 , according to some embodiments. The frame  130  includes the bottom plate  131 , a first side wall  133 , a second side wall  132 , and a front wall  134 . 
     The battery  190  provides power to various components of the device  100 . The power regulation board  165  receives power from the battery  190  and distributes power to various components at appropriate voltages. The motor control board  160  includes a main microcontroller unit (MCU)  362 . A voice processing board  170  processes voice commands from the user. The battery  190 , voice processing board  170 , and motor control board  160  are attached to the bottom plate  131 , in some embodiments. Motor control board  160  may support Brushless DC motor (BLDC) drive stage board  361  according to some embodiments. In some embodiments, the battery  190  and the boards  160 ,  165 ,  170 ,  361  are each be attached to the bottom plate  131  directly. In other embodiments some of all of the battery  190  and the boards  160 ,  165 ,  170 ,  361  are indirectly attached to the bottom plate  131  via any number of intervening components. 
       FIG.  14    shows another front and side perspective internal view of device  100 . In some embodiments, device  100  includes two extension arms  140 ; in other embodiments, device  100  includes one extension arm  140 ; in yet other embodiments, device  100  includes more than two extension arms  140 . Extension arm  140  may include a fixed rail  141  and an adjustable rail  143 . The fixed rail  141  is coupled to the front wall  134  the frame  130 . In one example, the fixed rail  141  is fixedly coupled to the front wall  134  of the frame  130  by bolts, welding, brazing, or any other attachment technique. A roller wheel  150  is coupled to each adjustable rail  143 . An overall length of the extension arm  140  may be adjusted by adjusting a position of the adjustable rail  143 , thus adjusting a distance between the roller wheel  150  and the belt shaft  125 . 
     In some embodiments, the adjustable rail  143  includes a smooth, stationary surface instead of a roller wheel, such that the connection line  5  may slide over the smooth stationary surface, which redirects the connection line  5  toward the user. 
     In some embodiments, an adjustable rail  143  may be used without a fixed rail  141 . For example, the adjustable rail  143  may be directly secured to the frame  130  of the device  100  at various positions. In other embodiments, the extension arm  140  includes rods coupled by adjustable hinges, which can be secured at different positions to achieve an adjustable overall length. In other embodiments, the overall length of the extension arm  140  may be adjustable by means of one or more folding mechanisms, one or more sliding mechanisms, and/or one or more telescoping mechanisms, to make the distance between the roller wheel  150  and the belt shaft  125  adjustable. 
       FIG.  14    shows the internal components of the device  100  supported by a frame  130 , according to some embodiments. The motor shaft  116  is supported by a bearing  129  in the first side wall  133  (see  FIG.  14   ). The belt shaft is supported by a bearing  126  in the first side wall  133  (see  FIG.  14   ). The belt shaft  125  is also supported by a bearing  128  in the second side wall  132  (see  FIG.  13   ). The belt shaft  125  is also supported by a center support  136  with a bearing  127  (see  FIG.  16   ). The frame  130  is aluminum or any other material capable of providing sufficient structural support. 
     According to some embodiments, one or more proximity sensors  199  are attached to the frame  130 . The proximity sensor  199  is configured to detect the proximity of a magnet  6  that is attached to the connection line  5 , and to send a signal to the controller  362 . The proximity sensor  199  may send a “1” to the controller  362  when the magnet  6  is close to the sensor  199 , indicating that the connection line  5  is in the upright position. In one embodiment, the proximity sensor  199  is a Hall effect sensor. 
     In some embodiments, as shown in  FIG.  15   , the fixed rail  141  may include two side walls  141 A and an end wall  141 B, with a plurality of holes  142  in each side wall  141 A. The adjustable rail  143  may include two side walls  143 A and an end wall  143 A, with a plurality of holes  146  in each side wall  143 A. The side walls  143 A of the adjustable rail  143  are distanced apart from each other so as to fit securely between the side walls  141 A of the fixed rail  141 . A first pin  145  and a second pin  147  are inserted into the holes  142 ,  146  on each side wall  141 A,  143 A to secure the fixed rail  141  to the adjustable rail  143 . The plurality of holes  142 ,  146  on each rail  141 ,  143 , allows the position of the adjustable rail  143  to be adjusted with respect to the fixed rail  141 , thus adjusting a position of the roller wheel  150  with respect to the belt shaft  125 . 
     In some embodiments, more than two pins are used to secure the fixed rail  141  to the adjustable rail  143 . In other embodiments, only one pin is used, and the fixed rail  141  provides rotational structural support to the adjustable rail  143 , for example with one or more flanges or one or more additional walls. In some embodiments, one or more of the pins only pass through one side wall of the fixed rail  141 A and one side wall of the adjustable rail  143 A. 
     In some embodiments, alternate mechanisms may be used to secure the adjustable rail  143  to the fixed rail  141  instead of or in addition to the pins  145 ,  147 . For example, the adjustable rail  143  can be secured to the fixed rail  141  with one or more clamps, one or more bolts, one or more screws, one or more pins, one or more collars, or any combination thereof. 
     In some embodiments, the fixed rail  141  and/or the adjustable rail  143  have more than two side walls. In other embodiments, the fixed rail  141  and/or the adjustable rail  143  have only one wall. Where the adjustable rail  143  has only one wall, the adjustable rail  143  may be branched at the end to accommodate the roller wheel  150 , or alternatively, the adjustable rail  143  may have a smooth surface to redirect the connection line  5 . 
     In some embodiments, the end wall  141 B of the fixed rail  141  is coupled to the front wall  134  of the frame  130 . In some embodiments, the end wall  141 B is affixed to the front wall  134  by bolts, welding, brazing, or attachment technique of sufficient structural strength. 
       FIG.  16    shows a ratchet and pawl mechanism in the device  100 . A ratchet wheel  195  is fixedly attached to the belt shaft  125 . A pawl  196  selectively engages with the ratchet wheel  195 . An actuator  330  receives commands from the controller  362  to selectively actuate the pawl  196  with an actuator rod  198 . When the pawl  196  is engaged with the ratchet wheel  195 , the belt shaft  125  may be maintained in a stationary position to resist torque applied to the belt shaft  125 . This may occur, for example, when the connection line  5  is supporting the weight of the user, causing the connection line  5  to apply a torque to the belt shaft  125 . The pawl  196  may also be engaged with the ratchet wheel  195  when the connection line  5  is being shorted and the belt shaft  125  is moving in a clockwise direction. In one embodiment, the actuator  330  is a latching solenoid. One or more motor Hall sensors  320  are configured to measure a position and speed of the motor  110 , according to some embodiments. 
     The front wall  134  has two slots  139  through which the connection line  5  passes, one of which is shown in  FIG.  16   .  FIG.  16    shows a U-shaped slot  139 , but other forms and shapes of channels, openings, and/or grooves may be employed. In one embodiment, a proximity sensor  199  is attached in one or more slots  139 . However, the proximity sensor  199  may also be disposed in any other location close enough to the fed out portion of the connection line such that the proximity sensor  199  can detect proximity of the magnet  6  on the connection line  5 . 
       FIG.  17    shows a schematic view of a connection line  5  according to one embodiment of the present disclosure. The connection line  5  may be one continuous belt. The magnet  6  is coupled to the connection line  5 . For example, in some embodiments the magnet  6  is sewn into the connection line  5  or inserted into a pocket in the connection line  5 . The magnet  6  is at a location such that the proximity sensor  199  senses proximity of the magnet  6  when the connection line  5  is in the upright position, in which the user is sitting upright. An attachment mechanism  7  is attached at one end of the connection line  5 . 
     In some embodiments, the attachment mechanism  7  is a D-ring that is attached to the connection line  5  and is configured to couple to a harness or item of clothing worn by the user. In other embodiments, the attachment mechanism may be a circular ring, a loop, or a buckle. In one embodiment the attachment mechanism is a breakaway buckle configured to fail above a predetermined force. In some embodiments the connection line  5  is a belt. In other embodiments the connection line is a cable, rope, cord, or strap. 
       FIG.  18    shows a top view of a connection line  5 A,  5 B according to another embodiment of the present invention. The connection line  5 A,  5 B includes a first belt segment  5 A and a second belt segment  5 B. The first belt segment  5 A is configured to be attached to the second belt segment  5 B with hook and loop fasters  9 A,  9 B. The first portion of the hook and loop fasteners  9 A is attached to the first belt segment  5 A and the second portion of hook and loop fasters  9 B is attached to the second belt segment  5 B. The first portion of the hook and loop fasteners  9 A may be hooks, and the second portion of the hook and loop fasteners  9 B may be loops. Alternatively, the first portion of the hook and loop fasteners  9 A may be loops, and the second portion of the hook and loop fasteners  9 B may be hooks. The hook and loop fasters  9 A,  9 B are attached to the respective belt segments  5 A,  5 B. In one embodiment, the hook and loop fasteners  9 A,  9 B may be sewn onto the respective belt segments  5 A  5 B. In other embodiments the hook and loop fasters  9 A,  9 B are attached to the belt segments  5 A,  5 B by other techniques such as gluing or stapling. 
     The hook and loop fasteners  9 A,  9 B maintain the tension in the connection line  5 A,  5 B below a desired threshold. If the tension in the connection line  5 A,  5 B, exceeds a threshold, the hook and loop fasteners  9 A,  9 B separate, thus separating the first belt segment  5 A from the second belt segment  5 B. 
     A magnet  6  is coupled to the first belt segment  5 A. In one embodiment, the magnet  6  is sewn into the first belt segment  5 A or inserted into a pocket in the first belt segment  5 A. The magnet  6  is at a location such that the proximity sensor  199  senses proximity of the magnet  6  when the connection line  5 A,  5 B is in an “Upright position” in which the user is sitting in an upright position. An attachment mechanism  7  is attached at one end of the connection line  5 A,  5 B. 
     In some embodiments, the attachment mechanism  7  is a D-ring that is attached to the connection line  5  and is configured to couple to a harness or item of clothing worn by the user. In other embodiments, the attachment mechanism may be a circular ring, a loop, or a buckle. In some embodiments the attachment mechanism is a breakaway buckle configured to fail above a predetermined force. 
       FIG.  19    shows a layout of an electrical system  300  for device  100  according to some embodiments. The device is powered by the battery  190 . In one embodiment, the battery  190  is a 24-volt (V) battery. A hardware switch  310  selectively connects or disconnects the battery  190  from the rest of the system  300 . The hardware switch  310  may be a switch, for example a mechanical switch or electrical button, that allows a user to shut off the battery  90  when the device  100  is not in use. 
     Voltage from the battery  190  is directly supplied to the 3-phase Brushless DC motor (BLDC) drive stage  361 . The voltage regulator  367  on the power regulation board  165  supplies power to other components at their respective operating voltages. The voltage regulator  367  provides a voltage, for example 9V, to the voice control micro-controller unit (MCU)  372 . The voltage regulator  367  also provides a voltage, for example 24 volts, to the H-Bridge driver  368 , which drives the actuator  330 . The voltage regulator  367  also provides a voltage, for example 5V, to the proximity sensors  199  and the proximity sensor circuitry  369 . The voltage regulator also provides a voltage, for example 5V, to the motor hall sensors  320  and the motor hall sensor circuitry  366 . In one embodiment, the voltage regulator  367 , the proximity hall sensor circuitry  369 , the H-bridge driver  368 , and the motor hall sensor circuitry  366  are all located on the power regulation board  165 . 
     In some embodiments the electronic system  300  include both a voice processing board  170  and a wired remote control board  335 . In another embodiment, the voice processing board  170  and the wired remote control board  335  are integrated on single board. In another embodiment, system  300  employs a voice control processing board  170  but not a remote control board  335 . In yet another embodiment, system  300  employs a remote control board  335  but not a voice control processing board  170 . 
     A user control MCU  337  may be utilized to receive signals from the voice control MCU  372  and from the buttons  336  and convert them to a uniform signal to send to the main MCU  362 . In one embodiment, a micro controller such as the Arduino Pro Mini may be used as the user control MCU  362 . User control MCU  337  may be located in the wired remote control board  335  that is wired to the main MCU  362 . 
     In one embodiment, as shown in  FIG.  20   , the remote control board  335  may include a plurality of buttons  336 . These buttons  336  may include a button  336 A that the user may use to implement a raising command telling the system to shorten the connection line  5  to lift the user up. Another button  336 B may be used to implement a lowering command telling the system to lengthen the connection line  5  in order to let the user down. Another button  336 C may be used to implement a stop command telling the system to stop lengthening or shortening the connection line  5 . Another button  336 D may be used to initiate the microphone  315  to receive voice control commands. Another button  336 E may be used to verify that a voice control command was received and parsed by the User Control MCU  337 . The User Control MCU  337 , shown in  FIG.  19   , sends the user commands from the buttons  336  to the Main MCU  362 . In some embodiments, the buttons  336  are mechanical switches. 
     The voice control module  371  receives a signal from a microphone  315  which receives a voice input from the user. In one embodiment, the voice control module  371  is implemented using a multi-purpose speech recognition module such as the Fortebit EasyVR 3 Plus. The voice control module  371  connects to the Voice Control MCU  372 , which is an Arduino Uno in some embodiments. The Voice Control MCU  372  is wired to the User Control MCU  337  located in the wired remote control board  337 . 
     The voice control MCU  372  may be configured to receive a voice command indicating that the user desires to be lifted up (a raising command, such as “Lift me up”), a voice command indicating that the user desires to be let down (a lowering command, such as “Let me down”), and a voice command indicating that the user desires for the connection line  5  to be locked in place (a stop command such as “Stop”). In some embodiments, the voice control MCU  372  is also configured to receive an initiation command (such as “Initiate”) indicating that a user desires to give a raising command or a lowering command. A speaker  325  is used to send audible feedback to the user to verify whether or not a voice command was recognized by the Voice Control MCU  372 . 
       FIG.  21    shows a speed control system  400  that may be used, for example, by device  100 . In one embodiment, speed control system  400  is implemented on the Main MCU  362 .  FIG.  21    demonstrates the closed-loop design of the system, with the interaction of the user  490  to the system evaluated as a disturbance (at  450 ) to the Pulse Width Modulated (PWM) output to the motor (from  440 ). The closed loop system increases or decreases the output to the motor (from  440 ) to maintain constant speed (reference speed  410 ). The Main MCU  362  generates the reference speed  410  for the system, and the controller includes a gain, Kp  430 . Both the reference speed  410  and the value of the gain Kp  430  can be adjusted in the software to meet the user&#39;s desired operation and/or comfort. 
     At block Kc1  440  the PWM commands used to control the motor (from  440 ) are calculated, based on the RPM comparison at  420 . This calculation centers the control output around the reference speed  410  and sets output boundaries to select a PWM setpoint output that does not exceed minimum and maximum PWM values, for example minimum and maximum physically achievable PWM values, according to some embodiments of the present disclosure. The gain Kg  460  represents the adjustment accounting for the gear ratio of the motor  110 . 
     The output speed of the motor is read by the motor Hall sensors  320  that are acting as encoders, according to some embodiments. This data is fed back into the Main MCU  362 , where encoder pulses are continually counted within a set time window (for example, 100 microseconds) to convert the encoder pulses into a measured speed. Kc2  480  represents the conversion from encoder pulses to the measured motor speed in RPM. This measured speed from Kc2  480  is compared (at  420 ) with the reference speed  410 , and the PWM control signal from the Main MCU  362  to the motor  110  is adjusted at  440  based on the comparison  420  to maintain a constant speed. 
     The speed control system allows the system to automatically adjust the torque supplied to the user depending on the current ability of the user to move their body in the chair by themselves, according to some embodiments. For users with less ability to move themselves, the system adjusts to supply more torque to move the user&#39;s weight. By using a control system to set the motor to run at a slow and constant speed, the torque that the motor  110  provides will automatically adjust based on the weight and strength of the user, according to some embodiments. 
     A software state machine  500  for the device  100  is shown in  FIG.  22   , and is implemented in the Main MCU  362  according to some embodiments. The state machine keeps track of the encoder count of the motor  110 , for example when device  100  is on, in order to keep an accurate record of the user&#39;s position. There are two checks to determine when the user has reached the upright position, according to some embodiments. When the encoder count, MEnc, is greater than or equal to TOP (at  521 ) or when the proximity hall sensor  199  is activated, i.e. PSens=1 (at  522 ), the user has reached a desired upright position and the state may be changed to LOCKED UPRIGHT  530 . Examples of each of the states shown in  FIG.  22    are discussed below. 
     The state machine  500  is in the LOCKED UPRIGHT  530  state when the user is in the upright position, according to some embodiments. The system enters this state when the motor encoder count is greater than or equal to TOP  521  or the proximity sensor  199  is activated  522 . The motor  110  is turned off in this state, and the actuator  330  is in a DOWN position such that the pawl  196  is engaged with the ratchet wheel  134 , thus locking the connection line  5  in place and supporting the user. 
     When the state machine  500  is in the IDLE state  510 , the motor  110  is off and the user is free to move without being locked in the upright position. The system enters the IDLE state  510  when the connection line  5  is fed out from the motor shaft  116  until the encoder count reaches the value “BOT”  553 , indicating that the connection line  5  is in the lowered position. The difference between BOT and TOP is the distance, in encoder counts, between the most downward position of the user and the upright position of the user. The system only transitions out of the IDLE state  510  upon receipt of a raising command  515  from the user. Commands may be received through the microphone  315  and/or the buttons  336 , among other possible command inputs. Upon receipt of the raising command  515 , the system may enter the MOVING UP state  520 . In the IDLE state  510 , the actuator  330  is in an UP position such that the pawl  196  is not engaged with the ratchet wheel  195 , according to some embodiments. 
     When the state machine  500  is in the MOVING UP state  520 , the motor wraps the connection line  5  around the belt shaft  125  to short the fed-out portion of the connection line  5 , thus pulling the user up. In one example the motor turns in a clockwise direction when the system is in the MOVING UP state  520 . In other embodiments the motor turns in a counter-clockwise direction when the system is in the MOVING UP STATE  520 . If a STOP command  525  is received from the user, the system will transition to the LOCKED MIDWAY state  540 , according to some embodiments. If the motor reaches the max encoder number, i.e. MEnc=TOP,  521 , or if the proximity sensor is activated, i.e. PSens=1, 522 the system willtransition to the LOCKED UPRIGHT state  530  in some embodiments. In the MOVING UP state  520 , the actuator  330  is in a DOWN position such that the pawl  196  is engaged with the ratchet wheel  195  in some embodiments. In other embodiments, the actuator  330  is in an UP position in the MOVING UP state such that the pawl  196  is disengaged with the ratchet wheel  195 . 
     When the state machine  500  is in the MOVING DOWN state  550 , the device  100  is increasing a length of the fed-out portion of the connection line  5  to let the user down. In one example, the motor  110  is turning counter-clockwise direction in the MOVING DOWN state to lengthen a fed-out portion of the connection line  5 . In other embodiments, the motor  110  is turning clockwise in the MOVING DOWN state to lengthen a fed-out portion of the connection line  5 . The system will enter the MOVING DOWN state  550  from the LOCKED UPRIGHT state  530  or the LOCKED MIDWAY state  540  upon receiving a lowering command  545  from the user, according to some embodiments. In the MOVING DOWN state  550 , the actuator  330  is in an UP position such that the pawl  196  is not engaged with the ratchet wheel  195 , according to some embodiments. 
     The state machine  500  enters the LOCKED MIDWAY state  540  from either the MOVING DOWN state  540  or the MOVING UP state  520  when a STOP command  525  is received, according to some embodiments. The system can leave this state in response to a raising command  515 ; the system can also leave this state in response to a lowering command  545 . The motor  110  is turned off in this state. In the LOCKED MIDWAY state  540 , the actuator  330  is in a DOWN position such that the pawl  196  is engaged with the ratchet wheel  195 , according to some embodiments. 
     The operation of the device according to some embodiments is described here. 
     The user  3  may begin in a down position, as shown in  FIG.  2 A . In this position, the state machine  500  is in the IDLE state  510 . If the user desires for the device  100  to assist the user  3  in sitting up, the user  3  presses the “Lift me Up” button  336 A on the wired remote control board  335 . Alternatively, the user may press the “Initiate Mic” button  336 D on the wired remote control board  335  or say “Initiate”, both of which indicate a desire to give a voice command. The initiation command is then processed by the user control MCU  337  and the voice control MCU  372 , and the speaker  325  outputs an audible verification that the initiation command was received and processed. The user may then give a voice command indicating a desire to be lifted up, such as “Lift me up.” The voice command is received by the microphone  315  and processed by the voice control module  371  and the voice control MCU  372  and sent to the user control MCU  337 . The speaker  325  outputs an audible verification indicating that the “Lift Me Up” command was received and processed. 
     The user control MCU  337  then sends a signal to the Main MCU  362  indicating that the “Lift Me Up” command was received. The state machine  500  switches to the “MOVING UP” state  520 . The user control MCU  337  sends a drive signal to the drive stage  361  of the motor  110  to rotate the motor  110  in a counter-clockwise direction. The user control module  337  also sends a signal to the H-bridge driver  368  to move the actuator  330  to the “down” position such that the pawl  196  is engaged with the ratchet wheel  195 . The Main MCU  362  continually monitors the speed of the motor using the signal from the motor Hall sensors  320 . The Main MCU adjusts the control signal to the drive stage  361  based on the measured speed, in accordance with the control scheme shown and described in relation to  FIG.  21   . 
     As the motor  110  turns counter-clockwise, the motor shaft  116  drives the belt shaft  125  in a counter-clockwise direction via the timing belt  120 . The connection lines  5  wrap around the belt shaft  125  as it rotates in a counter-clockwise direction. This, in turn, shortens a length of the fed-out portion of the connection lines  5 , causing the connection lines to slide over the roller wheels  150  toward the device  100 . The torso of the user  3 , which is connected to the connection lines  5  via attachment mechanisms  7 , is thus pulled up and back toward the upright position. 
     If the user desires to stop being raised before reaching the upright position the user may press the “Stop” button  336 C or give the audible voice command “Stop.” The command is processed and received by the Main MCU  362 , and the state machine enters the LOCKED MIDWAY state  540 . The Main MCU  363  sends a command to turn the motor  110  off, and the actuator  330  remains in the down position. The ratchet wheel  195  and pawl  196  counteract the weight of the patient on the connection line  5  by maintaining the belt shaft  125  in a static position. 
     If the user does not give a “Stop” command, the connection line  5  will continue to lift the user until the upright position is reached. The upright position is reached when the magnet  6  on the connection line  5  passes close to the proximity sensor  199 . The proximity sensor  199  then sends a “1” to the main MCU  362 , which enters the LOCKED UPRIGHT state  530  in response. The Main MCU  362  may also detect the upright position by keeping track of the encoder count from the motor Hall sensor  320 . The Main MCU  363  sends a command to turn the motor  110  off, and the actuator  330  remains in the down position. The ratchet wheel  195  and pawl  196  counteract the weight of the patient on the connection line  5  by maintaining the belt shaft  125  in a static position. 
     If the user in the upright position or midway position desires to be let down, he or she may press the “Let me down” button  336 B on the wired remote control  335  or give the audible command “Let me down.” The command is received and processed, and the state machine  500  enters the MOVING DOWN state. The main MCU  362  sends a signal to the H-bridge driver  368  to move the actuator to the up position, such that the pawl  196  is disengaged with the ratchet wheel  195 . The motor  110  drives the belt shaft  125  in a clockwise direction. The state machine remains in the MOVING DOWN state  550  until receiving a stop command (in which case the state machine  500  enters the LOCKED MIDWAY state  540 ), or until the encoder count from the motor hall sensor  320  indicates that the device is in the lowered position (in which case the state machine  500  enters the IDLE state  510 ). 
       FIGS.  23 - 25    show a device  200  according to an alternative embodiment. Certain components described here may operate similar to those described above for  FIGS.  1 ,  2 A,  2 B , and  8 - 16 . In this embodiment, the roller wheels  250 ,  255  and the motor box  230  are separately attached to the chair  1 . The motor box  230  is attached to the chair with a first set of shaft collars  231 . The lower roller wheels  255  are attached to the chair with a lower frame  242  and a second set of shaft collars  241 . The upper roller wheels  250  are attached to the chair with upper frames  251 , which may be directly attached to the chair  1 , for example with bolts. In some cases, a hair shield  8  is attached to upper frame  251  to discourage the user&#39;s hair from being caught in the roller wheel  151 . Connection line  5  may pass through a slot in the hair shield  8 , according to some embodiments. 
     In some embodiments, device  200  operates in substantially the same manner as device  100  discussed above. The motor  210  rotates a belt shaft  225  via a timing belt  220 . In other embodiments, the belt shaft  225  may be rotated directly by the motor  210 . The connection line  5  is coupled to the belt shaft  225  such that rotation of the belt shaft may lengthen or shorten a length of the fed-out portion of the connection line  5  depending on the direction of rotation of the motor  210  and the belt shaft  225 . The device  200  further includes a ratchet and pawl mechanism coupled the belt shaft  225 ; the ratchet and pawl mechanism being substantially the same as the ratchet and pawl mechanism shown and described in relation to  FIG.  10   . 
     Further, device  200  may use the electrical system as shown and described in relation to  FIG.  19   , and use the same boards and sensors. The remote control board  335  shown in  FIG.  20    may be used with device  200 . Furthermore, the device  200  may utilize the control scheme  400  shown and described in relation to  FIG.  21    and the state machine  400  shown and described in relation to  FIG.  22   . In some embodiments, the device  200  includes the continuous connection line  5  arrangement shown and described in relation to  FIG.  17   . In other embodiments, the device  200  includes the split connection line  5 A,  5 B arrangement shown and described in relation to  FIG.  18   . 
     A posture assistance device  100  according to some embodiments includes a motor  110  coupled to a frame  130 , wherein the frame  130  is configured to be attached to a wheelchair  1 ; a shaft  125  coupled to the motor  110 , wherein the motor  110  is configured to rotate the shaft  125 ; an extension arm  140  attached to the frame  130 , the extension arm  140  including a redirection surface  150 A, wherein the extension arm  140  is selectively adjustable to change a distance between the redirection surface  150 A and the shaft  125 ; and the extension arm  140  further including a connection line  5  coupled to the shaft  125  and configured to engage with the redirection surface  150 A, such that rotation of the shaft  125  changes a length a fed-out portion of the connection line  5 ; and an attachment mechanism  7  configured to couple the connection line  5  to a user  3 . 
     A posture assistance device  100  according to some embodiments includes a motor  110  coupled to a frame  130 , wherein the frame  130  is configured to be attached to a wheelchair  1 ; a shaft  125  coupled to the motor  110 , wherein the motor  110  is configured to rotate the shaft  125 ; an extension arm  140  attached to the frame  130 , the extension arm  140  including a redirection surface  150 A, wherein the extension arm  140  is selectively adjustable to change a distance between the redirection surface  150 A and the shaft  125 ; and the extension arm  140  further including a connection line  5  coupled to the shaft  125  and configured to engage with the redirection surface  150 A, such that rotation of the shaft  125  changes a length a fed-out portion of the connection line  5 ; and an attachment mechanism  7  configured to couple the connection line  5  to a user  3 ; and a controller  362 , wherein the controller is configured to receive a motor speed signal (from  320 ) representing a speed of the motor  110 ; and the controller  362  is configured to operate in a lifting mode  520 , wherein in the lifting mode  520 , the controller  362  is configured to send a drive signal to the motor  110 , the drive signal being based on a comparison (at  420 ) between the speed of the motor (from  320 ) and a reference speed  410 .