Patent Publication Number: US-7914427-B2

Title: Exercise assisting apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a exercise assisting apparatus of a passive type wherein the weight of a user acting on the legs of the user is varied by using a drive source to displace a seat with the user&#39;s feet resting on a foot supporting surface and the user&#39;s buttocks supported by the seat. 
     BACKGROUND ART 
     Japanese Patent Application Publication No. 2005-58733 (Patent Document 1) and Japanese Patent Application Publication No. 2007-89650 (Patent Document 2) propose an exercise assisting apparatus wherein a thigh muscle group is tensed and relaxed with hardly any extension of the knee, by displacing a seat with the user&#39;s feet resting on a foot supporting surface and the user&#39;s buttocks supported on a contact surface of the seat. This exercise assisting apparatus varies the user&#39;s weight acting on the user&#39;s legs by changing the ratio of the user&#39;s weight supported by a seat by displacing the position of the seat. 
     By an operation of this kind, the load is reduced compared to a case where the whole weight acts on the user&#39;s legs, and the thigh muscles are contracted with hardly any extension of the knee, whereby, for example, even a user having knee pain such as a patient with diabetes is able to strengthen the muscle group of the thigh, and furthermore since the muscle group of the thigh has a large volume, it is also expected to obtain a contribution to improvement in lifestyle-related diseases, by glucose metabolism associated with the muscular contraction. Moreover, by using a drive source to displace the seat, the user is able to exercise passively without exerting muscular force spontaneously, and therefore the load is light and consequently the apparatus can be used even by person&#39;s having a low capacity of movement. 
     Incidentally, an exercise assisting apparatus having the composition described above tenses and relaxes the thigh muscle group by changing the weight of the user that acts on the user&#39;s legs, with virtually no extension of the knees, and therefore the knee bending angle is an important factor in performing exercise effectively. As the analogy of a squatting movement readily shows, the load acting on the muscle group of the thigh varies with the knee bending angle. Furthermore, in the case of a user with knee pain, if a load acts on the user&#39;s knee while the knee is bent to a certain degree, the user often experiences pain and the bending angle must be restricted in order to make an apparatus usable by persons of this type as well. 
     At the present time, experimental results have been obtained indicating that the exercising effect is high and knee pain is not liable to occur, if the knee bending angle (in practice, the measured angle is that formed between the thigh and the lower leg on the front side of the knee) is set to 140 degrees, and hence this angle has been set as an appropriate angle. 
     In the apparatus described in Patent Document 2, it is proposed that the position of the seat is made adjustable in such a manner that the knee bending angle becomes the appropriate angle, and the position of the seat is adjusted automatically in accordance with an input parameter relating to the user&#39;s height. The position of the seat is adjustable in at least one of the vertical direction and the forward/rearward direction, and the horizontal distance from the foot position becomes greater if the seat is raised, while the horizontal distance from the foot position becomes smaller if the seat is lowered. 
     Patent Document 2 describes making the knee bending angle adjustable to an appropriate angle by adjusting the position of the seat, and suggests relating the position of the seat at which the knee bending angle becomes an appropriate angle to a parameter corresponding to the user&#39;s height, but does not provide a theory about how to change the seat position with respect to the user&#39;s height in order to achieve a desired knee bending angle. Consequently, in the composition described in Patent Document 2, it is not clear how the user&#39;s height and the position at which the user&#39;s buttocks are supported by the seat are related in order to set the knee bending angle to a desired angle. 
     DISCLOSURE OF THE INVENTION 
     The present invention is devised in view of the above reasons. An object in this invention is to provide an exercise assisting apparatus which is configured to adjust the knee bending angle to a desired angle regardless of the user&#39;s height. The adjustment is performed by specifying the range of adjustment of the position of a contact surface of the seat on the basis of the theory of the relationship of the position of the contact surface which supports a user&#39;s buttocks in a seat, the knee bending angle, and the user&#39;s height. 
     The exercise assisting apparatus relating to the present invention comprises: a seat having a contact surface configured to support thereon a buttock of a user with the user&#39;s feet resting on a predetermined foot supporting surface; a seat driving mechanism configured to use a driving source for displacing the seat in a direction of varying the user&#39;s weight acting on the user&#39;s legs; and an elevator mechanism configured to adjust a vertical position and a forward/rearward position of the contact surface of the seat in order to keep a user&#39;s knee bending angle at a prescribed angle while the user is sitting on the seat held at a reference position with the user&#39;s feet placed on a predetermined position on the foot supporting surface. The elevator mechanism is configured to adjust the position of the contact surface of the seat member within a restricted range along a line which is inclined rearwardly and upwardly with respect to a vertical direction and is deduced by a user of maximum physique and a user of minimum physique. Therefore, it is possible to restrict theoretically the range of adjustment of the position of the contact surface of the seat, and as a result of this, adjustment which keeps the knee bending angle at a desired angle can be performed reliably, irrespectively of the height of the user. 
     Desirably, the elevator mechanism is composed so as to comprise an elevator driver for displacing the position of the seat with respect to a base held at a fixed position. The elevator driver is configured to vary the position of the seat linearly along a path inclined rearwardly and upwardly at a predetermined angle within a vertical plane in which the seat is allowed to move vertically and forward/rearward. Since the elevator mechanism varies the position of the seat linearly in this way, then the elevator mechanism can be achieved by means of a simple mechanism which moves the seat linearly. 
     Desirably, the elevator driver comprises a fixed member secured to the base, a movable member configured to move along a linear path relative to the fixed member and support the seat, and a drive motor configured to move the movable member towards and away from the fixed member. In this case, the driving force of the drive motor can be used to raise and lower the seat, and the position of the seat can be adjusted even when the user&#39;s buttocks are supported on the seat. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic side view showing an exercise assisting apparatus relating to one embodiment of the present invention; 
         FIG. 2  is a schematic plan view of the exercise assisting apparatus; 
         FIG. 3  is a diagram describing the operational principles of the exercise assisting apparatus; 
         FIG. 4  is an exploded perspective diagram of the exercise assisting apparatus; 
         FIG. 5  is an exploded perspective diagram of a seat driver used in the exercise assisting apparatus; and 
         FIG. 6  is a side view diagram of a seat driver used in the exercise assisting apparatus. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     As shown in  FIG. 1  and  FIG. 2 , the exercise assisting apparatus relating to one embodiment of the present invention has a base  10  which is disposed in a fixed position on a floor, or the like, and provided on top of this base  10  are: a seat support base  20  having a seat  21  which supports the buttocks of a user M provided on the upper end thereof, and a handle post  30  having a handle  31  which the user M grips with his or her hands as necessary provided on the upper end thereof. A foot stand  40  is arranged on the base  10  so as to be located between the seat support base  20  and the handle  30 . The foot stand  40  has the upper surface of which forms a foot supporting surface  40   a . The foot stand  40  restricts the position of the user&#39;s feet by means of the user M placing his or her feet on the foot supporting surface  40   a.    
     Provided on the seat support base  20  are: a seat driver  50  which causes the seat  21  to oscillate, and an elevator mechanism  60  which raises and lowers the seat  31  and the seat driver  50  with respect to the base  10 . The composition of the seat driver  50  and the elevator mechanism  60  is described below. 
     The seat driver  50  operates the drive source to swing the seat  21 , thereby the seat driver  50  changing the weight of the user M who sits on the contact surface  21   a  of the seat  21  and who places the feet on the supporting surface  40   a  of the foot stand  40 . As a result, the weight of the user M that acts on the user&#39;s knee is changed. In other words, the body weight of the user M is supported by the buttocks and the legs in a distributed fashion. In this context, when the position of the user&#39;s buttock is varied, the weight supported by the buttocks is increased and decreased. According to variation of the weight supported by the buttock, the weight acting on the legs is changed. 
     When the knees are bent by a prescribed angle, then if the ratio of the body weight supported by the seat  21  is decreased, the load acting on the thighs of the user M is increased and the muscle group of the thigh region can be made to contract, similarly to bending the knees by performing a squat movement. In other words, when the seat  21  is caused to oscillate by the drive source, the thigh muscle groups repeat a tensing and relaxing action by means of a passive movement which is not a spontaneous movement of the user M. In other words, it is possible principally to exercise the thigh region by means of the seat driver  50  causing the seat  21  to oscillate. 
     The direction of oscillation of the seat  21  is desirably set in such a manner that no shearing force acts on the knee joints. When the buttocks of the user M are supported by the contact surface  21   a  of the seat  21 , the user M&#39;s feet naturally adopt an attitude where the distance between the toe tips is greater than the distance between the heels, as shown in  FIG. 2 , and the angle of opening θ 2  between the feet can be determined from the position where the feet are placed on the foot stand  40 . Therefore, it is possible to exercise without applying a shearing force to the knee joints by oscillating the seat  21  in a direction following the central lines that link the heels and the tips of each foot when the user&#39;s feet are placed on the foot stand  40 . In other wards, it is preferred to provide a time period during which the seat  21  moves obliquely rightwards and forwards and a time period during which the seat  21  moves obliquely leftwards and forwards when the seat  21  moves forward from the rear end position in the range of oscillation. Consequently, it is possible to make the user&#39;s weight act respectively on the thigh area of the left legs and the right legs, without applying a shearing force to the knee joints. 
     In the example shown in  FIG. 1 , the contact surface  21   a  which is the upper surface of the seat  21  is a substantially horizontal surface. However, the exercise which stimulates muscular contraction of the thigh muscle group is performed by changing the weight of the user M that is acting on the user&#39;s legs. Therefore, it is desirable that the contact surface  21   a  of the seat  21  making contact with the buttocks of the user M should be inclined downwardly in the forward direction of the direction of oscillation of the seat  21 . In other words, desirably, the portion which supports the right buttock area of the user M in the front end portion of the seat  21  in inclined obliquely downwards in the rightward and forward direction. Similarly, desirably, the portion which supports the left buttock area of the user M is inclined obliquely downwards in the leftward and forward direction. If a shape of this kind is adopted, then when the seat  21  is moved forward from the rear end position of the oscillation range, the user&#39;s weight acting on the legs is liable to increase and the exercising effect can be raised. 
     A control and display apparatus  32  is provided in the central part of the handle  31  on the upper end portion of the handle post  30 . The control and display apparatus  32  is provided for operation of issuing instructions in respet of the operation of the seat driver  50  and the elevator mechanism  60 , and for display of measures indicating the amount exercise, and the like. The user M is able to stabilize the position of his or her upper body by gripping the handle  31 . 
     The structure of the handle support base  20  is described in more detail below. As shown in  FIG. 4 , the handle support base  20  has a hollow supporting column  22  which is erected on the base  10 , and the lower end portion of the elevator mechanism  60  is accommodated inside the supporting column  22 . The elevator mechanism  60  has an elevator base  61  which ascends and descends slidably with respect to the supporting column  22 , and the seat driver  50  is mounted on the upper end of the elevator base  61 . Consequently, the seat driver  50  is able to move with respect to the base  10 , together with the seat  21 . 
     The center line of the supporting column  22  is a straight line which is inclined rearwardly with respect to the vertical direction (in other words, inclined rearwardly and upwardly), and by means of the elevator base  61  sliding inside the supporting column  22 , the position of the contact surface  21   a  of the seat  21  can be adjusted in a single straight line following the center line of the supporting column  22 , in the vertical direction. In other words, the position of the contact surface  21   a  of the seat  21  is adjusted in the forward/rearward direction simultaneously with being adjusted in the vertical direction. In addition, the further the position of the contact surface in the upward direction, the further its position in the rearward direction. The angle formed between the center line of the supporting column  22  and the base  10  is described hereinafter. 
     The elevator base  61  is driven to ascend and descend by an elevator driver  62  which comprises a drive motor  63 . The elevator driver  62  comprises, in addition to the drive motor  63 , a column-shaped fixed member  64  which is fixed to the base  10 , and a movable member  65  which comprises a ball screw that screws into the fixed member  64 , and employs a composition whereby the movable member  65  is advanced and retracted with respect to the fixed member  64  by decelerating the rotation of the drive motor  63  so as to rotate the movable member  65 . The elevator base  61  is installed on the upper end portion of the movable member  65 , and ascends and descends with the advancing or retreating movement of the movable member  65  with respect to the fixed member  64 . 
     The elevator base  61  comprises a seating  61   a  and a pair of guide plates  61   b . The seat driver  50  is mounted on the seating  61   a . A pair of the guide plates are provided on the lower surface of the seating  61   a . The upper end portion of the movable member  65  in the elevator driver  62  is coupled to the lower surface side of the seating  61   a . Furthermore, rollers  61   c  are installed on the outer surfaces of the guide plates  61   b , and by guiding these rollers  61   c  in rail sections  22   a  provided on the inner surface of the supporting column  22 , it is possible to move the elevator base  61  smoothly with respect to the supporting column  22 . A sensor which determines the amount of advance or retreat of the movable member  65  with respect to the fixed member  64  is provided, and the rotation of the drive motor  63  is controlled in such a manner that the value determined by the sensor coincides with a target value specified in accordance with an input via the display and control unit  32 . However, since this composition is not an essential feature, further description thereof is not included here. 
     A tubular elevator cover  66  is attached to the seating  61   a  of the elevator base  61 . The lower end portion of the elevator cover  66  overlaps with the outer surface of the supporting column  22  in the range of extension and contraction of the elevator driver  62 , and by this means the elevator base  61  is not exposed to the exterior even when the elevator driver  62  is extended by the maximum amount. Moreover, a mechanical unit cover  67  formed from a cloth-like soft material is attached to the seating  61   a  of the elevator base  61 . The mechanical unit cover  67  prevents the seat driver  50  from being exposed to the exterior by covering the portion between the seating  61   a  and the seat  21 . 
     Next, the seat driver  50  is described with reference to  FIG. 5  and  FIG. 6 . The seat driver  50  constitutes a mechanism which causes the seat  21  to oscillate together with the seating  61   a  of the elevator base  61 . The seat driver  50  is installed axially on a front and rear pair of axle plates  51   a ,  51   b , and axles  52   a ,  52   b . The front and the rear pair of axle plates  51   a ,  51   b  are provided in an upright fashion on the upper surface of the seating  61   a . The front and rear axles  52   a ,  52   b  are disposed coaxially, and by means of the seat driver  50  rotating about these axles  52   a ,  52   b , the seat  21  which is coupled to the seat driver  50  can be caused to oscillate leftwards and rightwards (in the directions indicated by arrow N in  FIG. 4 ). 
     The seat driver  50  comprises a front and rear pair of frame plates  53   a ,  53   b , and these two frame plates  53   a ,  53   b  are coupled via a left and right-hand pair of frame side plates  54   a ,  54   b . The lower end portions of a front link  55  and a rear link  56  which rotate about an axis in the left/right direction are installed axially by means of axles  55   a ,  56   a  on the two frame side plates  54   a ,  54   b , and the upper end portions of the front link  55  and the rear link  56  are installed axially on a base plate  57  by means of axles  55   b  and  56   b . Here, the upper end portion of the rear link  56  is installed axially on a bearing plate  57   a  which is fixed to a base plate  57  rather than being axially installed directly on the base plate  57 . 
     The range of movement of the base plate  57  is restricted in such a manner that the front end portion of the base plate  57  moves through a circular arc centered on the axle  55   a , and the rear end portion of the base plate  57  moves through a circular arc centered on the axle  56   a . Here, the rear link  56  is formed to a longer dimension than the front link  55 , and hence the front end portion and the rear end portion of the base plate  57  have different radii of curvature, whereby the angle of inclination of the upper surface changes as the base plate  57  moves forwards and rearwards. More specifically, if the position shown in  FIG. 6  is taken as the rear end position of the range of movement in the forward/rearward direction, then as the base plate moves forward, the front end portion of the base plate  57  descends relatively with respect to the rear end portion thereof, thereby increasing the angle of inclination of the upper surface. Conversely, if the base plate is moved rearwards from the front end position, the front end portion of the base plate  57  rises upwards relatively with respect to the rear end portion, thereby reducing the angle of inclination of the upper surface. In other words, the seat  21  can be moved in the forward/rearward direction (the direction indicated by arrow X in  FIG. 4 ).  FIG. 4  depicts linear movement, but in actual practice, because the angle of inclination of the forward/rearward direction changes, then the displacement combines a linear movement and a rotational movement in the forward/rearward direction. 
     The motor  71  which is a drive source for oscillating the base plate  57  with respect to the base plate  61   a  is held by both frame side plates  54   a  and  54   b . Furthermore, the motor  71  is disposed vertically in such a manner that the output shaft thereof projects in the upward direction. A worm gear  72  is coupled to the output shaft of the motor  71 . A first shaft  73  and a second shaft  74  are supported on the frame side plates  54   a  and  54   b , and a worm wheel  75  which meshes with the worm gear  72  is provided on the first shaft  73 . A gear  76  is also provided on the first shaft  73  and the gear  76  meshes with a gear  77  which is provided on the second shaft  74 . 
     Eccentric cranks  78  which rotate together with the first shaft  73  are attached respectively to either end of the first shaft  73 . One end of an arm link  79  is axially installed respectively on each eccentric crank  78 , and the other ends of the arm links  79  are axially installed respectively on axle pins  55   c  which project to the left and right of the front link  55 . 
     By means of this composition, when the motor  71  turns and the first shaft  73  rotates, the front link  55  moves back and forth reciprocally in the forward/rearward direction about the axles  55   a  due to the eccentric cranks  78  and the arm links  79 , and the front portion of the base plate  57  oscillates in the forward/rearward direction about the axles  55   a  (the direction indicated by arrow X in  FIG. 4 ). Furthermore, after the rear link  56  has turned about the axles  56   a , the angle of inclination of the upper surface changes with the movement of the base plate  57  in the forward/rearward direction. 
     On the other hand, an eccentric pin  74   a  is provided in a standing fashion on one end portion of the second shaft  74 , and one end portion of an eccentric rod  80  is installed axially on this eccentric pin  74   a . The other end portion of the eccentric rod  80  is coupled in an oscillatable fashion to a coupling piece  81  which is attached to the seating  61   a . The pin  74   a  and the eccentric rod  80  may be provided on either the left or right-hand side of the seat driver  50 . 
     By means of this composition, if the motor  71  is turned and the second shaft  74  is rotated via the first shaft  73 , then the height position of the eccentric pin  74   a  with respect to the seating  61   a  changes with the pin  74   a  and the eccentric rod  80 , and as a result, the base plate  57  oscillates leftwards and rightwards about the axles  52   a  and  52   b  (the direction indicated by arrow N in  FIG. 4 ). 
     A brushless DC motor, or the like, is used for the motor  71 , and a DC motor is also used for the drive motor  63 . Here, since the motor  63  is disposed in a space which is surrounded by the frame plates  53   a ,  53   b , the frame side plates  54   a ,  54   b , the seating  61   a  and the base plate  57 , and since the gears  75  to  77  are also disposed in the same space, then the seat driver  50  is compact. 
     Basically, the seat driver  50  moves the seat  21  in a rightward forward and downward direction and a leftward forward and downward direction. However, in the composition described above, by appropriately setting the gear ratios of the gears  76  and  77 , and the phase differential between the eccentric crank  78  and the eccentric pin  74   a , then apart from a V-shaped path of movement of the seat  21  (where two reciprocal forward and rearward movements are performed during one reciprocal movement in the left/right direction), the path of movement of the seat  21  can also be set to a W shape (where four reciprocal forward and rearward movements are performed during one reciprocal movement in the left/right direction), or a figure of eight shape (where two reciprocal forward and rearward movements are performed during one reciprocal movement in the left/right direction and the rear end positions are skewed to the left and right-hand sides), and so on. 
     The operation and halting of the drive motor  63  and the motor  71  are commanded by operating the control and display apparatus  32 . In other words, a control section for instructing the operation or halting of the motor  71  and the speed of revolution of the motor  71  is provided in the control and display apparatus  32 , and hence the exercise time period and the exercise intensity can be specified. Furthermore, a control section for raising or lowering the seat  21  is provided in such a manner that the knee bending angle assumes an appropriate angle. The control section and the display section provided in the control and display apparatus  32  are connected to the operation of the motor  71  and the drive motor  63  by means of a control circuit (not illustrated). 
     In the exercise assisting apparatus described above, it is necessary to keep the knee bending angle at an appropriate angle in order to promote contraction of the thigh muscle group without causing knee pain, even in the case of a user M who suffers from knee pain. That is, the exercise assisting apparatus gives the movement of changing the user&#39;s weight acting on the thigh to the user having the knee angle at a prescribed angle. When the user uses the exercise assisting apparatus, the user&#39;s feet are fixed in position by resting on the foot stand  40 . Here, it is desired that the knee joint is aligned along the vertical direction to the foot joint in order to increase the load acting on the thigh. Therefore, due to these restricting conditions, the knee bending angle is governed by the position of the seat  21 . Leg dimensions vary between different individuals, and change significantly with the height of the user M. 
     As described above, the height position of the seat  21  is adjustable by means of the elevator mechanism  60 , and furthermore, by moving the seat  21  in a straight line which is inclined rearwards with respect to the base  10 , the elevator mechanism  60  adjusts the position of the contact surface  21   a  of the seat  21  in such a manner that the further the contact surface moves upwards, the further the contact surface is positioned rearwards. 
     The direction in which the elevator mechanism  60  moves the seat  21  is described with reference to  FIG. 3 . It is supposed that with the user&#39;s feet resting on the foot stand  40 , the straight line linking the foot joint J 2  and the knee joint J 1  (in other words, the shinbone) coincides with the vertical direction. Furthermore, it is supposed that the angle of opening θ 2  between the two feet (see  FIG. 2 ) when the feet are resting on the foot stand  40  is 20 degrees. Moreover, the knee bending angle is θ 1  (see  FIG. 1 ), the distance between the hip joint J 3  and the knee joint J 1  is L 1 , the distance from the upper surface of the foot stand  40  to the knee joint J 1  is L 2 , and the angle formed between the direction of movement of the seat  21  and the horizontal plane (in other words, the angle formed between the central line of the support column  22  and the base  10 ) is φ. 
     If these parameters are used, then at the position P 1  where the buttocks make contact with the contact surface  21   a  of the seat  21  (the intersection of the plumb line from the center of gravity of the user&#39;s trunk with the contact surface  21   a ), the horizontal distance X between position P 1  and the foot joint J 2  and the height Y of position P 1  from the upper surface of the foot stand  40  can be represented by the following expressions.
 
 X=L 1·sin(180°−θ1)·cos(θ2/2)
 
 Y=L 1·cos(180°−θ1)+ L 2 −L 3
 
L 3  is the distance between the position P 1  and the hip joint J 3 . For example, if the height of the user M is in the range of 140 to 170 cm, then by adopting standard values for the distances L 1  and L 2 , it is possible to derive the angle φ by calculation. In other words, taking the differences in the distances L 1  and L 2  due to difference in physique as ΔL 1  and ΔL 2  respectively, it is possible to determine the angle φ if the maximum value and minimum value of the difference in physique are employed.
 
     When calculation was made using the value for a female aged  65  to  79  (standard value) as the minimum physique value, and using the value for a male aged  65  to  79  (standard value) as the maximum physique value, then it was possible to identify 75 degrees as the angle φ whereby the knee bending angle could be kept to 140 degrees in both persons. In other words, when the straight line passing through the positions P 1  determined in respect of the maximum and minimum physiques of the user M was found, it was seen that this line was inclined rearwards with respect to the vertical direction and formed an angle of 75 degrees with respect to the horizontal surface. 
     Here, since the angle φ is determined from the positions P 1  which are specified for the two points relating to a minimum physique and a maximum physique, then although compatibility with a user M of another physique is not necessarily guaranteed, the aforementioned distances L 1  and L 2  are predicted to change in a substantially linear fashion with respect to the user&#39;s height and therefore linear interpolation between the maximum value and the minimum value is possible. Furthermore, since linear interpolation is possible, then as described above, it is possible to employ a simple mechanism which performs linear movement as the elevator mechanism  60 . Here, it is also possible to determine three or more points in respect of differences in physique, and to trace the path of movement of the seat  21  by the elevator mechanism  60  as a curve.