Patent Publication Number: US-2010113986-A1

Title: Walking assist apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a walking assist apparatus, more particularly to a battery charging device for a walking assist apparatus worn on the lower body of a human being (user) to assist his/her walking. 
     2. Description of the Related Art 
     Recently reported walking assist apparatuses of this type include, for instance, the one according to the technology set out in Japanese Laid-Open Patent Application No. 2007-20909 (Patent Document 1). 
     The walking assist apparatus of the reference is equipped with a support member capable of supporting the user, shoe units capable of accommodating the user&#39;s feet, leg links having first links connected to the support member through joints and second links connected to the shoe units through second joints, actuators connected to the first links and second links, a controller that controls the operation of the actuators, and a battery, which walking assist apparatus assists the user walk by operating the actuators to produce relative movement between the first and second links. 
     When the remaining battery charge of the walking assist apparatus set out in the reference 1 runs low, the battery is recharged either after removal from the apparatus or through contacts as installed in the apparatus. In either case, the battery is troublesome to recharge. 
     SUMMARY OF THE INVENTION 
     The object of this invention is therefore to overcome this drawback by providing a walking assist apparatus equipped with actuators, a controller for controlling the operation of the actuators, and a battery, in which charging of the battery is made simple. 
     In order to achieve the object, this invention provides a walking assist apparatus, having: a support member that is adapted to support an user; a pair of shoe units that are adapted to accommodate feet of the user: a pair of leg links each having a first link connected to the support member through a first joint and a second link connected to each of the shoe units through a second joint; actuators each connected to the first links and second links: a controller that controls operation of the actuators; and a battery that is adapted to supply operating power at least one of the actuators and the controller; and assists walking of the user by operating the actuators to produce relative movement between the first and second links; wherein the improvement comprises: a primary coil installed in a floor on which the user walks on; a secondary coil that is installed in at least one of the shoe units and is supplied with non-contact supply of power by magnetic induction from the primary coil; and a charging circuit that charges the battery with direct current output rectified by a rectifier circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects and advantages of the invention will be more apparent from the following description and drawings in which: 
         FIG. 1  is a perspective view of a walking assist apparatus according to an embodiment of the invention, showing its overall configuration including a battery charging device; 
         FIG. 2  is a perspective view of the apparatus shown in  FIG. 1 ; 
         FIG. 3  is a side view of the apparatus shown in  FIG. 2 ; 
         FIG. 4  is a front view of the apparatus shown in  FIG. 2 ; 
         FIG. 5  is a side sectional view of a drive mechanism, first link and other components shown in  FIG. 2 , etc.; 
         FIG. 6  is a plan view of a loop coil shown in  FIG. 1 ; 
         FIG. 7  is a sectional view along VII-VII in  FIG. 6 ; 
         FIG. 8  is a side view of a shoe unit shown in  FIG. 1 . etc.; 
         FIG. 9  is a plan view of the shoe unit shown in  FIG. 8 ; 
         FIG. 10  is a plan view of the shoe unit shown in  FIG. 8 ; 
         FIG. 11  is a set of explanatory views showing the apparatus illustrated in  FIG. 1 , etc., assisting the walking (movement) of a worker (user) engaged in automobile assembly; 
         FIG. 12  is a time chart showing the relationship between the assembly work illustrated in  FIG. 11  and remaining battery charge and the like; 
         FIG. 13  is a set of explanatory views showing another example of deployment of the loop coil illustrated in  FIG. 1  in the case where the apparatus provides walking (movement) assistance to a worker (user) making the rounds of different work sites inside a facility; 
         FIG. 14  is a time chart showing the relationship between tasks illustrated in  FIG. 13  and remaining battery charge and the like; and 
         FIG. 15  is an explanatory view showing another example of the loop coil shown in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A preferred embodiment of the walking assist apparatus according to the invention is explained with reference to the attached drawings in the following. 
       FIG. 1  is an explanatory view of the walking assist apparatus according to an embodiment of the invention, showing its overall configuration including a battery charging device.  FIG. 2  is a perspective view of the walking assist apparatus shown in  FIG. 1 .  FIG. 3  is a side view thereof  FIG. 4  is a front view thereof. 
     The walking assist apparatus will first be explained with references to  FIGS. 2 to 4 . The walking assist apparatus, designated A in the drawings, comprises a support member  10  that supports a user (human being) P seated astraddle thereon, a pair of left and right shoe units  12  to be worn on the left and right feet of the user P, a pair of left and right leg links  14  provided between the support member  10  and the shoe units  12 , and drive mechanisms  16 . The walking assist apparatus is fastened to the lower body of the user P by a belt (not shown) provided on the support member  10  and assists the user P walk. 
     The left and right leg links  14  are made of aluminum. Each comprises a first link (thigh link)  22  connected to the support member  10  through a first joint  20  (corresponding to the human hip joint), a second link (shank link)  26  connected to the associated shoe  12  through a second joint  24  (corresponding to the human ankle joint), and a third joint  30  (corresponding to the human knee) connecting the first link  22  and second link  26 . 
     The first link  22  and second link  26  of the leg link  14  are connected to the associated drive mechanism  16  which moves (drives) them relative to each other with the third joint  30  as a pivot point (i.e., about the third joint  30 ). 
     The support member  10  comprises a saddle-like seat  10   a  that supports the user P seated astraddle thereon, a support frame  10   b  located near the seat  10   a  to support it, and a back rest  10   c  rising from the support frame  10   b  to above the rear end (as viewed by the user P) of the seat  10   a  to contact the lower back of the user P. A grip  10   d  that can be grasped by the user P is attached to the back rest  10   c.    
     As best shown in  FIG. 3 , the support frame  10   b  of the support member  10  is forward-canted overall (in the direction of forward movement when the user P sits on the seat  10   a ). The seat  10   a  is made of a cushioning material, and the support frame  10   b  and back rest  10   c  are made of materials of higher rigidity than the seat  10   a.    
     The first joints  20  that connect the leg links  14  and support member  10  each comprises an arc-shaped guide rail  32  fastened to the support member  10  and a slider  34  that engages with the guide rail  32  and is fastened to one end of the associated leg link  14 . The guide rails  32  and sliders  34  are made of aluminum. 
     A plurality of rollers  36  are attached to each slider  34 . The rollers  36  are fitted in a groove formed in the guide rail  32  to roll along the groove. Therefore, as shown in  FIG. 2 , each slider  34  engages with the associated guide rail  32  to be movable alone it. 
     In other words, each leg link  14  can swing about the center of curvature  32   a  (swing pivot point) of the associated guide rail  32  in the longitudinal direction of the support member  10 . Moreover, the guide rails  32  are pivotally supported on the back rest  10   c  of the support member  10  by a support shaft  32   b  installed sideways to extend in the longitudinal direction of the support member  10 , thereby enabling the guide rails  32  to swing about the support shaft  32   b  in the lateral direction of the support member  10 . 
     Thus the leg links  14  can swing forward and backward (in the direction of user P travel) about the centers of curvature  32   a  of the guide rails  32  as the swing pivot points, so that when the point of action of the upper body weight of the user P relative to the support member  10  shifts forward of the swing pivot points  32   a  to make the support member  10  descend forward, since the swing pivot points  32   a  is located above the support member  10  in the gravitational direction, the point of action of the body weight is displaced rearward below the swing pivot point  32   a,  thereby shortening the fore-aft distance between the swing pivot point  32   a  and the point of action of the body weight to reduce rotational moment acting on the support member  10 . 
     Next, when the point of action of the body weight has moved as far as directly under the swing pivot point  32   a,  the rotational moment acting on the support member  10  becomes zero and the support member  10  becomes stable. Thus, the support member  10  converges on the stable state by itself, so that the support member  10  does not shift forward or backward at the location of the user P&#39;s crotch. 
     The guide rails  32  are enabled to swing sideways (relative to the direction of user P travel) about the swing pivot point (support shaft)  32   b,  so that the leg links  14  can swing sideways to make it possible for the user P to swing the legs outward at will. 
     Each of the shoe units  12  comprises a shoe  12   a  to be worn on a foot of the user P, an L-shaped (as viewed from the front looking rearward along the path of user P travel) connecting member  12   b  made of carbon material and extending to inside the shoe  12   a  for enabling the corresponding foot of the user P to rest thereon, and an insole  12   c  of urethane rubber or similar rubbery elastic material that lies on the upper surface of the connecting member  12   b.  The second link  26  of each leg link  14  is connected to the associated connecting member  12   b  through the associated second joint  24  of triaxial structure. 
       FIG. 5  is a side sectional view of the drive mechanisms  16  and the associated first link  22 , etc. 
     The first link  22  and second link  26  of the leg link  14  are connected to the associated drive mechanism  16 . The drive mechanism  16  comprises an actuator (electric motor)  42  located near the upper end of the first link  22 , an output shaft  42   b  for outputting the rotation of the motor  42  trough reduction gearing  42   a,  a drive crank arm  44  fastened to the output shaft  42   b.  and a driven crank arm  46  fastened to the second link coaxially with a joint shaft  30   a  of the third joint  30 . 
     The drive crank arm  44  and the driven crank arm  46  are interconnected by the first link  22 . Specifically, the first link  22  is connected by a rod  22   a  pivotally attached at one end to the drive crank arm  44  by a pivot  22   b  and at the other end to the driven crank arm  46  by a pivot  22   c,  thereby establishing rotatable connections. Thus, more specifically, the first link  22  is constituted as a quadric chain comprising the first link  22 , the drive crank arm  44 , the rod  22   a  and the driven crank arm  46 . 
     As shown in  FIG. 5 , the first link  22  is disposed so that a line drawn to connect its pivot  22   b  on the drive crank arm  44  with its pivot  22   c  on the driven crank arm  46  intersects a line drawn to connect the output shaft  42   b  of the actuator  42  with the joint shaft  30   a  of the third joint  30 . A battery  50  housed within a cover  22   d  of the first link  22  supplies power for operating the motors  42  and the like. 
     The walking assist control for assisting the user P walk will be explained next. 
     Each shoe unit  12  is provided on the undersurface of its insole  12   c  with a pair of front and rear single-axis force sensors  60  that produce outputs proportional to the loads acting at the middle toe (MP (metacarpophalangeal) joint) region and heel region of the user P&#39;s foot. In addition, each second joint  24  incorporates a biaxial force sensor  62  that produces an output proportional to the force acting on the second joint  24  (resultant of the forces produced by the weights of the support member  10  and the associated leg link  14 ). 
     The outputs of the sensors  60  and  62  are sent to a controller  64  housed inside the support frame  10   b  of the support member  10 . The controller  64  is configured as a microcomputer equipped with a CPU, ROM, RAM and input-output (I/O) ports. It is supplied with operating power from the battery  50  and executes assist control for controlling the operation of the motors  42  so as to produce assist forces that assists the user P walk. 
     More specifically, the controller  64  multiplies the value of the assist forces set in advance by the proportion of the total load acting on the feet of the user P that is borne by the individual feet calculated from the outputs of the force sensors  60 , and defines the products obtained as the desired values of the assist forces to be produced in the respective leg links  14 . For example, where the load (weight) of the apparatus A is 60 (N) and the assist force is 30 (N), the set value is 90 (N). 
     Each assist force acts along the line in  FIG. 3  (designated L 1 ; hereinafter sometimes called “reference line”) that interconnects the fore-aft swing pivot point  32   a  of the leg link  14  in the first joint  20  and the fore-aft swing pivot point of the leg link  14  in the second joint  24 . So the controller  64  detects the actual assist force acting along the reference line L 1  based on the output of the force sensor  62  and controls the operation of the motor  42  of the associated drive mechanisms  16  to make the actual assist force detected equal to the desired value. 
     More specifically, when the user P is supported as seated on the seat  10   a  of the support member  10 , the controller  64  operates the actuators (motors)  42  of the drive mechanisms  16  to produce relative movement between the first links  22  and the second links  26  of the leg links  14  about the joint shafts  30   a  of the third joints  30 , thereby helping the user P walk by producing supporting forces, i.e., assist forces, to support at least part of the user P&#39;s body weight. 
     The assist forces produced in the leg links  14  are transmitted through the support member  10  to the trunk of the user P to assist walking by reducing the load acting on the legs of the user P. The user P is presumed to be a worker at a factory or the like who, as discussed later, works in a standing posture. 
     The explanation of  FIG. 1  will be resumed. The walking assist apparatus A according to this embodiment is equipped with a secondary coil  70  that is installed in one of the shoe units  12  and is supplied with non-contact supply of power by magnetic induction from a loop or circular coil (primary coil)  100  installed in the floor F on which the user walks on, and a rectifier circuit  72  that rectifies the output of the secondary coil  70  and a charging circuit  74  that charges the battery  50  with the direct current output rectified by the rectifier circuit  72 . 
     As illustrated, the loop coil  100  is a coil of a suitable number of turns wound in a circle of around 1 meter diameter so that the shoe units  12  of the walking assist apparatus A can fit inside it with room to spare. The loop coil  100  is connected to a commercial or other AC power source  102 . 
       FIG. 6  is a plan view of the loop coil  100  in the floor F, and  FIG. 7  is a sectional view along VII-VII in  FIG. 6 . 
     As shown in  FIGS. 6 and 7 , the loop coil  100  is embedded in the floor F, made of concrete or the like, in a workspace at a factory or other such facility. It is covered with a circular cover  104  made of a non-dielectric material like rubber. 
       FIGS. 8 ,  9  and  10  are side, plan and rear views of the shoe unit  12 . 
     As illustrated, the secondary coil  70  is a coil of a suitable number of turns wound in an oval or rectangle with a breadth (minor axis) of around 4 cm. It is accommodated under the insole  12   c  of either the left or right shoe unit  12 . User walking passes through alternate two-leg support phases and one-leg support phases (when the other leg is in the swing phase). The toe end of the shoe  12   a  on the supporting leg side greatly deforms during the transition from the two-leg support phase to the one-leg support phase, while the heel end of the shoe  12   a  on the swinging leg side deforms during the transition from heel contact to the two-leg support phase. 
     The secondary coil  70  is accommodated at a location close to the heel end. i.e., at or near the heel end of the shoe  12   a  because the heel end deforms less than the toe end. Moreover, this arrangement ensures that electromagnetic induction is not impaired even if the toe of the shoe  12   a  is fitted with a metal toe safety protector (not shown). 
     Power transmitted from the loop coil  100  to the secondary coil  70  by non-contact electromagnetic induction is passed through the rectifier circuit  72  and charging circuit  74  to charge the battery  50 . As shown in  FIG. 1 , the rectifier circuit  72  for rectifying the output of the secondary coil  70  and the charging circuit  74  for charging the battery  50  are accommodated in the first link  22  near the battery  50 . 
     The loop coil  100  is supplied with relatively large current from the AC power source  102 . The transmission of this power through the secondary coil  70 , rectifier circuit  72  and charging circuit  74  to the battery  50  therefore enables quick charging of the battery  50 . 
     The installation of the loop coil  100  will be explained. 
       FIG. 11  is an explanatory view showing the walking assist apparatus A assisting the walking (movement) of a worker (user) P engaged in automobile assembly.  FIG. 12  is a time chart showing the relationship between the assembly work and remaining battery charge and the like. 
     The automobile assembly work shown in  FIG. 11  involves regular movement through a circuit (travel circuit) including a travel segment to a part supply station, a travel segment during which the worker carries the supplied part, and a travel and work segment during which the user moves and works. In the illustrated case, the loop coil  100  is installed in the floor of the part supply station midway of the circuit. 
     In this arrangement, the user (worker) P is made to reside at the site of loop coil  100  for at least a predetermined time (e.g., 20 seconds) while being supplied with the part. The battery  50  can be charged utilizing this residence time. 
     Moreover, the site of loop coil  100  installation is determined in the light of the capacity of the battery  50 , in other words, the site of the midway of the circuit is determined according to the capacity of the battery  50 . Therefore, as shown in  FIG. 12 , the battery  50  is recharged before its remaining charge falls below a predetermined value, so that the worker P can continue the work shown in  FIG. 11  without interruption except when residing at the part supply station. 
       FIG. 13  is an explanatory view showing another example of loop coil  100  deployment in the case where the walking assist apparatus A provides walking (movement) assistance to a worker (user) P making the rounds of different work sites inside a facility.  FIG. 14  is a time chart showing the relationship between the tasks and remaining battery charge and the like. 
     In the work shown in  FIG. 13 , the worker P monitors at a monitor station on the first floor, next climbs stairs and moves to and monitors at a monitor station on the second floor, and then climbs stairs and moves to and monitors at a monitor station on the third floor. The loop coil  100  is therefore deployed at each monitor station and the worker P is made to reside thereat for at least a predetermined time to be recharged with the battery  50 . Thus, also in this work, the loop coil  100  is installed in the floor at a location midway of the travel circuit, when the worker P makes regular movement through the travel circuit. 
     Therefore, as shown in  FIG. 14 , the battery  50  is recharged before its remaining charge falls below a predetermined value, so that the worker P can continue the work shown in  FIG. 13  without interruption except when residing at the monitoring sites. 
     As stated above, the embodiment is configured to have a walking assist apparatus A, having: a support member ( 10 ) that is adapted to support an user (P); a pair of shoe units ( 12 ) that are adapted to accommodate feet of the user; a pair of leg links ( 14 ) each having a first link ( 22 ) connected to the support member through a first joint ( 20 ) and a second link ( 26 ) connected to each of the shoe units through a second joint ( 24 ); actuators ( 42 ) each connected to the first links and second links; a controller ( 64 ) that controls operation of the actuators; and a battery ( 50 ) that is adapted to supply operating power at least one of the actuators and the controller; and assists walking of the user by operating the actuators to produce relative movement between the first and second links; wherein the improvement comprises: a primary coil (loop coil)  100  installed in a floor (F) on which the user walks on; a secondary coil ( 70 ) that is installed in at least one of the shoe units ( 12 ), more precisely the shoe ( 12   a ) and is supplied with non-contact supply of power by magnetic induction from the primary coil; and a charging circuit ( 74 ) that charges the battery with direct current output rectified by a rectifier circuit ( 72 ). With this, the user can be charged with the battery if he resides or stands at the site on the floor F where the secondary coil  70  is installed, thereby enabling to make charging (recharging) of the battery simple. 
     In the apparatus, the secondary coil ( 70 ) is installed at a location close to a heel end of the one of the shoe units ( 12 ), more precisely shoe ( 12   a ). With this, in addition to the effects mentioned above, it becomes possible to protect the damage of the secondary coil since the heel end deforms less than the toe end. Moreover, this arrangement ensures that electromagnetic induction is not impaired even if the toe of the shoe  12   a  is fitted with a metal toe safety protector. 
     In the apparatus, the primary coil ( 100 ) is installed in the floor (F) at a location midway of a travel circuit (such as a part supply station or monitor station), when the user makes regular movement through the travel circuit. With this, in addition to the effects mentioned above, the user can continue the work while being charged with the battery  50  during the work. 
     In the apparatus, a site of the midway is determined according to a capacity of the battery ( 50 ). With this, in addition to the effects mentioned above, it becomes possible to decrease the capacity of the battery  50  and as a result, it becomes possible to decrease the entire weight of the apparatus A and decrease the energy consumption. 
     In the apparatus, the secondary coil ( 70 ) is wound in a circle such that the at least one of the shoe units ( 12 ) fits in the circle with room to spare. With this, in addition to the effects mentioned above, the charging (recharging) of the battery  50  can be further facilitated. 
     In the apparatus, the primary coil ( 100 ) is embedded in the floor and covered by a cover ( 104 ), or the primary coil ( 100 ) is installed in the floor inside a carpet ( 106 ). With this, in addition to the effects mentioned above, the primary coil  100  can be protected from the damage. 
     Although this invention has been explained with reference to an embodiment, this invention is not limited to the embodiment. For example, the foregoing embodiment is configured to embed the loop coil  100  in the floor F and cover it with the cover  104 , but it is also acceptable, as shown in  FIG. 15 , to install or embed the loop coil  100  in the floor inside a carpet  106 . 
     In addition, although it has been explained that electric motors are used as the actuators  42  and that the battery  50  supplies them with operating power, it is acceptable for the actuators  42  to be hydraulic/pneumatic devices whose operation is controlled by a microcomputer-based computer system or the like supplied with operating power from the battery  50 . 
     Further, although it has been explained that the secondary coil  70  is provided in only one of the left and right shoe units  12 , secondary coils  70  can be provided in both the left and right shoe units  12 . 
     Moreover, the support member  10  is not limited to a structure enabling use in a seated posture but can be of a structure using a belt such as taught by Japanese Laid-Open Patent Application No. 2006-187348. 
     Japanese Patent Application No. 2008-285946 filed on Nov. 6, 2008, is incorporated by reference herein in its entirety. 
     While the invention has thus been shown and described with reference to specific embodiments, it should be noted that the invention is in no way limited to the details of the described arrangements; changes and modifications may be made without departing from the scope of the appended claims.