Patent Publication Number: US-2022211562-A1

Title: Assistive apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to an assistive apparatus. 
     BACKGROUND 
     Patent Literature 1 and Patent Literature 2 disclose assistive apparatuses that assist a standing operation of an assisted person. The assistive apparatus of Patent Literature 1 is provided with a driving device including a rotating device that tilts a support member supporting the assisted person, and a linear motion device that lifts and lowers the support member and the rotating device. The assistive apparatus of Patent Literature 2 is provided with a driving device including three rotating devices that enable the support member to be moved to an arbitrary position and angle. 
     PATENT LITERATURE 
     
         
         Patent Literature 1: International Publication No. 2018/116472 
         Patent Literature 2: JP-A-2011-019571 
       
    
     SUMMARY 
     Technical Problem 
     There is a demand for the assistive apparatus to simplify the driving device from the viewpoint of downsizing and manufacturing cost while allowing the support member that assists the standing operation of the assisted person to move. In particular, the linear motion device configured to constitute the driving device has high accuracy required for the constituent members and is likely to cause an increase in manufacturing cost. In addition, when the driving device includes three or more rotating devices or the like, the device may be easily increased in size, and the configuration of a power source and a path of a signal may be complicated. 
     It is an object of the present specification to provide an assistive apparatus capable of downsizing and reducing the manufacturing cost while assisting the standing operation of the assisted person. 
     Solution to Problem 
     The present specification discloses an assistive apparatus including a base, a first arm provided on the base and configured to revolve around a horizontal first center axis, a second arm provided on the first arm and configured to revolve around a horizontal second center axis, a support member provided on the second arm and configured to support an upper half body of an assisted person, and a control device configured to perform a cooperative operation of the first arm and the second arm in assisting a standing operation of the assisted person supported by the support member, in which the first arm is configured to be located ahead of a knee bending position at which an upper thigh portion and a lower thigh portion of the assisted person bend in an initial state before execution of assistance of the standing operation. 
     The present specification discloses an assistive apparatus including a base, a first arm provided on the base and configured to revolve around a horizontal first center axis, a second arm provided on the first arm and configured to revolve around a horizontal second center axis, a support member provided on the second arm and configured to support an upper half body of an assisted person, and a control device configured to perform a cooperative operation of the first arm and the second arm in assisting a standing operation of the assisted person supported by the support member, in which operation processing for assisting the standing operation includes a first step of revolving the second arm rearward in parallel with revolving the first arm forward at an initial stage of the standing operation. 
     Advantageous Effect of the Invention 
     With such a configuration, the support member can be moved along a predetermined movement trajectory by the first arm and the second arm constituting the mechanism including two joints with respect to the base. As a result, the assistive apparatus can assist the standing operation of the assisted person. In addition, the assistive apparatus has a configuration for causing the revolving of the first arm and the revolving of the second arm to cooperate with each other, so that it is possible to downsize and reduce the manufacturing cost of the assistive apparatus as compared with a configuration including a linear motion device or three or more rotating devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an assistive apparatus of an embodiment as viewed obliquely from a rear. 
         FIG. 2  is a side view illustrating the assistive apparatus in an initial state where it supports an assisted person in a sitting posture. 
         FIG. 3  is a side view illustrating the assistive apparatus that supports the assisted person in an intermediate posture. 
         FIG. 4  is a side view illustrating the assistive apparatus in a standing support state where supports the assisted person in a standing posture. 
         FIG. 5  is a diagram illustrating operations of a first arm, a second arm, and a support member in assisting an operation of a standing operation, as well as a movement trajectory of a lower reference position and a movement trajectory of an upper reference position. 
         FIG. 6  is a diagram illustrating an operation of the second arm and a movable range of the second arm in assisting the operation of the standing operation. 
         FIG. 7  is a flowchart illustrating processing for assisting the operation of the standing operation. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     1. Configuration of Assistive Apparatus  1   
     A configuration of assistive apparatus  1  of the embodiment will be described with reference to  FIGS. 1 to 4 . Assistive apparatus  1  assists assisted person M (refer to  FIG. 2  or the like) in a standing operation from a sitting posture to a standing posture, and in a sitting operation from the standing posture to the sitting posture. When assistive apparatus  1  supports an upper half body of assisted person M in the standing posture, one assisting person can pull assistive apparatus  1  or the like to move assistive apparatus  1  to, for example, a moving target in an assisting facility. 
     The “standing posture” means a posture in which a lower half body of assisted person M is standing. As illustrated in  FIG. 4 , in the present specification, a posture in which buttocks Mt is lifted from the sitting posture, the lower half body stands, and the upper half body is tilted forward is defined as a standing posture of assisted person M. That is, assistance for the standing operation is assistance for an operation in which the posture is such that buttocks Mt of assisted person M is lifted, and the upper half body is tilted forward to place the mass of the upper half body in assistive apparatus  1 . In addition, the assistance for the sitting operation is assistance for an operation of lowering the position of buttocks Mt of assisted person M. 
     As illustrated in  FIG. 1 , assistive apparatus  1  is provided with base  10 . More specifically, base  10  includes frame  11  forming a main body of base  10 . In the present embodiment, base  10  includes foot placing table  12  provided so as to be horizontal to frame  11 . Both legs Mg of assisted person M are placed on foot placing table  12 . Assistive apparatus  1  may adopt an aspect in which foot placing table  12  is not provided depending on the level of assisting required by assisted person M. Base  10  includes first actuator support portion  13  provided upward closer on a front side of an upper surface of foot placing table  12 . 
     Three wheels  16  to  18  are each provided on the right and left sides on the lower side of foot placing table  12 . Each of wheels  16  to  18  has a steering function for changing the movement direction. Foremost wheel  16  has a locking function for restricting movement. Assistive apparatus  1  is capable of not only moving and changing the direction in the front-rear direction, but also laterally moving (moving in the true lateral direction) and spin turn (revolving on the spot) by the steering function of six wheels  16  to  18 . 
     Assistive apparatus  1  is provided with knee pad member  80 . Knee pad member  80  is a member provided on base  10  and on which the knee of assisted person M assisted in the standing operation abuts. Knee pad member  80  is provided to stabilize the standing operation or the sitting operation of assisted person M by determining the position of the knee of assisted person M. Knee pad member  80  includes support rod  81 , buffer member  82 , and position adjustment portion  83 . Support rod  81  is formed in an L-shape and supports buffer member  82 . 
     Buffer member  82  is a cushion material provided on support rod  81  and extending in the right-left direction. Buffer member  82  is covered with, for example, a protective cover made of cloth or leather. Position adjustment portion  83  slidably supports support rod  81  in the front-rear direction. Position adjustment portion  83  is configured to be able to adjust the position of buffer member  82  in the front-rear direction so as to be compatible with a physique and the sitting posture of assisted person M. After the positional adjustment using position adjustment portion  83 , the positions of support rod  81  and buffer member  82  in the front-rear direction are set by positioning pins (not illustrated). 
     Assistive apparatus  1  is provided with first arm  21  and second arm  22 . As illustrated in  FIG. 2 , first arm  21  is provided on base  10  and revolves around horizontal first center axis  21 A. Second arm  22  is provided on first arm  21  and revolves around horizontal second center axis  22 A. In the present embodiment, as illustrated in  FIG. 2 , first arm  21  is formed so as to extend upward from first center axis  21 A in an initial state before the assisted person is boarded. In addition, second arm  22  is formed so as to extend rearward from second center axis  22 A in the initial state. 
     As described above, first arm  21  and second arm  22  constitute an operation mechanism including two joints with respect to base  10 . First arm  21  and second arm  22  support member  40  that supports the upper half body of assisted person M so as to be movable in the up-down direction and the front-rear direction of base  10 . In addition, first arm  21  includes two second actuator support portions  25  provided rearward from a lower side of a center portion in the up-down direction and disposed side by side in the extension direction of first arm  21  with each other and third actuator support portion  26 . In addition, second arm  22  includes fourth actuator support portion  27  protruding downward from a center portion in the right-left direction and provided downward. Detailed configurations of first arm  21  and second arm  22  will be described later. 
     Assistive apparatus  1  is provided with driving device  30  that causes first arm  21  and second arm  22  to revolve in operation processing for assisting the standing operation of assisted person M supported by support member  40 . In the present embodiment, driving device  30  is provided with first actuator  31  and second actuator  32 . First actuator  31  and second actuator  32  are telescopic actuators. 
     More specifically, first actuator  31  includes main body portion  31   a  and movable portion  31   b . Main body portion  31   a  is formed in a cylindrical shape having an open end portion. Movable portion  31   b  is formed in a columnar shape having a smaller diameter than that of main body portion  31   a , and a first end thereof is inserted from the opening of main body portion  31   a . First actuator  31  moves movable portion  31   b  in the extension direction with respect to main body portion  31   a  by a driving force of a motor (not illustrated). 
     In addition, since second actuator  32  is the same type as first actuator  31 , detailed descriptions thereof will be omitted. Main body portion  32   a  and movable portion  32   b  of second actuator  32  correspond to main body portion  31   a  and movable portion  31   b  of first actuator  31 . First actuator  31  and second actuator  32  can use different types of drive sources such as a pressure driving source using hydraulic pressure or pneumatic pressure instead of the above motor. 
     Here, first actuator  31  and second actuator  32  are provided behind first arm  21 . In addition, first actuator  31  is provided so as to be tilted forward from base  10  side toward first arm  21  side. Specifically, first actuator  31  is provided so as to be rotatable at a first end on main body portion  31   a  side to first actuator support portion  13  of base  10 , and is provided so as to be rotatable at a second end on movable portion  31   b  side to second actuator support portion  25  of first arm  21 . 
     In addition, second actuator  32  is provided above first actuator  31  and tilted rearward from first arm  21  side toward second arm  22  side. Specifically, second actuator  32  is provided so as to be rotatable at a first end on movable portion  32   b  side to third actuator support portion  26  of first arm  21 , and is provided so as to be rotatable at a second end on main body portion  32   a  side to fourth actuator support portion  27  of second arm  22 . 
     With the configuration as described above, driving device  30  causes first arm  21  to revolve forward around first center axis  21 A by an extension operation of first actuator  31 , and causes first arm  21  to revolve rearward by a shortening operation of first actuator  31 . In addition, driving device  30  causes second arm  22  to revolve forward around second center axis  22 A by the extension operation of second actuator  32 , and causes second arm  22  to revolve rearward by the shortening operation of second actuator  32 . In driving device  30 , the operations of first actuator  31  and second actuator  32  are controlled by control device  70 . 
     In addition, as described above, both first actuator  31  and second actuator  32  are configured to be provided behind first arm  21 . As a result, first and second actuators  31  and  32  are housed on the rear side where base  10  and second arm  22  are disposed with respect to first arm  21 , so that entire assistive apparatus  1  is compact in the front-rear direction. Furthermore, by providing first actuator  31  and second actuator  32  so as to be tilted forward or rearward as described above, it is possible to ensure a space for assisted person M to board behind first arm  21  and below second arm  22 . 
     Assistive apparatus  1  is provided with support member  40  that supports the upper half body of assisted person M. Support member  40  is provided on second arm  22 . In the present embodiment, support member  40  is provided with trunk support portion  41  and a pair of side support portions  42 . Trunk support portion  41  is formed in a planar shape close to the trunk shape of assisted person M. Trunk support portion  41  is formed of a material that can be flexibly deformed. The support surface of trunk support portion  41  is in surface contact with a front surface of the trunk of the upper half body of assisted person M to support the trunk. More specifically, the support surface of trunk support portion  41  supports a range extending from a chest portion Mb to an abdomen portion Ma of assisted person M. Trunk support portion  41  is attached to a rear end portion of second arm  22 . 
     In addition, trunk support portion  41  is supported so as to be able to freely tilt in the front-rear direction with respect to second arm  22 . Specifically, trunk support portion  41  is configured to be able to tilt within a predetermined angle range in the clockwise direction in  FIG. 2  from the state illustrated in  FIG. 2 . The above “free tilt” means a tilt that can be manually moved, not a tilt driven by an actuator or the like. 
     The pair of side support portions  42  is supported by trunk support portion  41  and supports the side of assisted person M. More specifically, the pair of side support portions  42  are provided on the right and left sides of trunk support portion  41 . Side support portion  42  is swingably supported by trunk support portion  41 . Side support portion  42  is formed in an L-shape by a rod-like member. The surface of side support portion  42  is covered with a material that can be flexibly deformed. 
     Assistive apparatus  1  is provided with first handle  51  and second handle  52 . First handle  51  is formed in a substantially rectangular frame shape. First handle  51  is formed so as to extend forward and upward from the rear end portion of second arm  22 . Side portions of first handle  51  are gripped by both hands of assisted person M. Furthermore, the side portion and the front portion of first handle  51  are gripped by the assisting person to move assistive apparatus  1 . 
     Second handle  52  is integrally provided on a front surface of trunk support portion  41 . Second handle  52  is formed in an elongated U-shape. Second handle  52  is provided with a base shaft portion fixed to a lower portion of trunk support portion  41  and extending in the right-left direction, and a gripping portion extending from both ends of the base shaft portion toward first handle  51  side. 
     Assistive apparatus  1  is provided with controller  60  that receives an operation of assisted person M or the assisting person. As illustrated in  FIG. 1 , controller  60  is provided with up button  61 , down button  62 , standing button  63 , and sitting button  64 . Up button  61  and down button  62  receive a request for adjusting the position of support member  40  in the up-down direction. Standing button  63  receives an assistance request for the standing operation. Sitting button  64  receives an assistance request for the sitting operation. Controller  60  may omit up button  61  and down button  62 , for example, in a case where the adjustment movement in the up-down direction is included in the movement trajectory of support member  40 . 
     Assistive apparatus  1  is provided with control device  70  that controls driving device  30  and moves support member  40  supporting assisted person M. Control device  70  performs a cooperative operation of first arm  21  and second arm  22  in assisting the standing operation or the sitting operation of assisted person M. Here, the above “cooperative operation” means that a first one of first arm  21  and second arm  22  operates in accordance with the state of a second one. Accordingly, the operation in which the revolving of first arm  21  and the revolving of second arm  22  cooperate with each other includes a state where both first arm  21  and second arm  22  are revolved, and a state where only one of first arm  21  and second arm  22  is revolved. Driving device  30  moves support member  40  along a predetermined movement trajectory by performing the cooperative operation of first arm  21  and second arm  22  as described above. Control device  70  controls the movement of support member  40  in response to an adjustment request or an assistance request inputted via controller  60 . 
     In the present embodiment, controller  60  is assumed to have an operation request (adjustment request or assistance request) only during a period when any button is pressed. In addition, in a case where there is an operation request, control device  70  may not execute an operation corresponding to the request depending on the operation state of assistive apparatus  1 . This is assumed to be, for example, a case where the posture of assisted person M is inappropriate for the movement of support member  40  in accordance with the request, or a case where the movement of support member  40  reaches the boundary of the movable range. 
     2. Detailed Configurations of First Arm  21  and Second Arm  22   
     Detailed configurations of first arm  21  and second arm  22  of assistive apparatus  1  configured as described above will be described with reference to  FIG. 2, and 4 to 6 . Here, the state before the execution of the operation processing for assisting the standing operation of assisted person M is defined as an initial state of assistive apparatus  1  (refer to  FIG. 2 ). In the initial state of assistive apparatus  1 , the position of support member  40  in the up-down direction is adjusted in accordance with, for example, the physique of assisted person M or the height of seat surface  91  of chair  90 . In addition, a state where trunk support portion  41  of support member  40  supports the trunk of assisted person M in the standing posture from below is defined as a standing support state (refer to  FIG. 4 ). 
     As described above, first arm  21  is provided on base  10  so as to be revolvable around first center axis  21 A. In the present embodiment, first arm  21  is formed in a linear shape along first virtual line ML 1  passing through first center axis  21 A and second center axis  22 A so as to extend upward from first center axis  21 A in the initial state of assistive apparatus  1 . In addition, second arm  22  is formed so as to extend rearward from second center axis  22 A in the initial state of assistive apparatus  1 . 
     Here, as illustrated in  FIG. 2 , first center axis  21 A is set to be located in the vicinity of an attaching position of front wheel  16  in the front-rear direction, and to be located between base  10  and knee pad member  80  in the up-down direction. Specifically, first center axis  21 A is located at a position lower than knee bending position PKb of the assisted person. In addition, second center axis  22 A is located behind first center axis  21 A in the initial state of assistive apparatus  1 . That is, the extension direction of first arm  21  is tilted rearward with respect to a vertical axis in the initial state. 
     Furthermore, second center axis  22 A is located ahead of knee bending position PKb at which upper thigh portion Mh and lower thigh portion Me of assisted person M bend in the initial state of assistive apparatus  1 . More specifically, in the present embodiment, as illustrated in  FIG. 2 , the above “knee bending position PKb” is an intersection point between upper thigh virtual line NL 1  passing through the center portion of upper thigh portion Mh of assisted person M and extending in the extension direction of upper thigh portion Mh, and lower thigh virtual line NL 2  passing through the center portion of lower thigh portion Me of assisted person M and extending in the extension direction of lower thigh portion Me when starting the assistance of the standing operation. As described above, first arm  21  is configured so that second center axis  22 A is located ahead of knee bending position PKb of assisted person M while tilting rearward in the initial state of assistive apparatus  1 . 
     Second center axis  22 A may be located directly above knee pad member  80  or ahead of knee pad member  80  in the initial state of assistive apparatus  1 . In addition, as illustrated in  FIGS. 4 and 5 , second center axis  22 A may be located ahead of a front end of a portion of trunk support portion  41  in contact with the trunk in the standing support state where trunk support portion  41  supports the trunk of assisted person M in the standing posture. First arm  21  and second arm  22  are configured to have a positional relationship between first center axis  21 A and second center axis  22 A as described above, respectively. Supplementally, first arm  21  extends from first center axis  21 A to a height at which the chest portion Mb of assisted person M is located, and is tilted rearward in the initial state of assistive apparatus  1 . 
     In the initial state of assistive apparatus  1 , second arm  22  ensures the length in the horizontal direction from second center axis  22 A to the front surface of support member  40  in contact with the chest portion Mb of assisted person M. In addition, second arm  22  is configured to extend obliquely rearward from second center axis  22 A to a connecting portion with support member  40  in the standing support state of assistive apparatus  1 . 
     As described above, by ensuring a predetermined length of second arm  22 , a sufficient space can be formed between both legs Mg and first arm  21  in a posture in which assisted person M contacts the chest portion with support member  40 . 
     As a result, it is possible to prevent the interference between the members other than knee pad member  80  and both legs Mg of assisted person M while ensuring a range in which the position of knee pad member  80  can be adjusted. In addition, as illustrated in  FIG. 4 , by ensuring the length of second arm  22 , it is possible to lift support member  40  to a sufficient height as well as first arm  21  in the standing support state. 
     As illustrated in  FIG. 5 , movable range Rm 1  of first arm  21  may include an angle at which first virtual line ML 1  passing through first center axis  21 A and second center axis  22 A is in the vertical direction. In the present embodiment, movable range Rm 1  of first arm  21  is set to a range in which first virtual line ML 1  can revolve back and forth by 25 degrees with respect to an angle coincident with a vertical axis. 
     In addition, as illustrated in  FIG. 6 , movable range Rm 2  of second arm  22  may include an angle at which second virtual line ML 2  passing through second center axis  22 A and the reference position set in support member  40  is in the horizontal direction. In the present embodiment, movable range Rm 2  of second arm  22  is set to a range in which second virtual line ML 2  can revolve up and down by 25 degrees with respect to an angle coincident with a horizontal axis. 
     As illustrated in  FIG. 2 , lower reference position Pb and upper reference position Pu may be set in the above reference position. Lower reference position Pb is set at a lower end of a portion of trunk support portion  41  in contact with the trunk. In addition, as illustrated in  FIG. 2 , upper reference position Pu is set at an upper end of a portion of trunk support portion  41  in contact with the trunk. Upper reference position Pu may be set at a position of the side of assisted person M. 
     3. Operation Processing of Standing Operation by Assistive Apparatus  1   
     Operation processing for assisting the standing operation by assistive apparatus  1  will be described with reference to  FIGS. 2 to 7 . The above operation processing of the standing operation includes a first step of moving forward support member  40  and a second step of moving forward and lifting support member  40 . The first step and the second step of the operation processing are actually executed in series, and in a case where support member  40  follows a smooth movement trajectory, it is not always possible to feel the switching of steps. 
     In the present embodiment, a step of advancing support member  40  so that the mass of the upper half body of assisted person M is substantially placed on support member  40  is referred to as a first step. The first step includes an operation of revolving second arm  22  rearward in parallel with revolving first arm  21  forward at an initial stage of the standing operation. By executing the first step, assisted person M shifts from the sitting posture, which is the initial state illustrated in  FIG. 2 , to the intermediate posture in which the upper half body illustrated in  FIG. 3  is tilted forward. In addition, a step of advancing and lifting support member  40  so as to lift the upper half body of assisted person M is referred to as a second step. At this time, assisted person M shifts from the intermediate posture illustrated in  FIG. 3  to the standing posture in which both legs Mg is extended, which is the end state illustrated in  FIG. 4 . 
     Here, when the revolving of first arm  21  and the revolving of second arm  22  cooperate with each other, swinging support member  40  may have a portion that advances and a portion that retreats with respect to base  10 , and similarly, may have a portion that rises and a portion that descends with respect to base  10 . Therefore, hereinafter, a movement of a reference position set to a position that is integrally moved with support member  40  will be described as a movement of support member  40 . As illustrated in  FIG. 2 , lower reference position Pb and upper reference position Pu may be set in the above reference position. 
     As illustrated in  FIGS. 2 to 5 , lower reference position Pb moves along first movement trajectory Tb during the standing operation of assisted person M. In addition, during the standing operation of assisted person M, upper reference position Pu moves along second movement trajectory Tu. That is, control device  70  controls the movement of support member  40  in cooperation with the revolving of first arm  21  and the revolving of second arm  22  so that lower reference position Pb moves along first movement trajectory Tb or so that upper reference position Pu moves along second movement trajectory Tu. 
     As illustrated in  FIG. 2 , at the initial stage of the operation processing for assisting the standing operation, assisted person M is in a seated state (state of the sitting posture) in which buttocks Mt is in contact with seat surface  91  of chair  90 . Assistive apparatus  1  is placed in the initial state of operation processing for assisting the standing operation by an operation by assisted person M or the assisting person. The above operation includes the positional adjustment of assistive apparatus  1  with respect to assisted person M, and the height adjustment of support member  40  in accordance with the physique or the like of assisted person M. 
     In the initial state of assistive apparatus  1 , assisted person M places both legs on foot placing table  12 . At this time, assisted person M causes the front surface of the trunk to be in surface contact with trunk support portion  41 . In addition, assisted person M causes the knee to come into contact with the rear surface of knee pad member  80 . Furthermore, assisted person M grips first handle  51 . At this time, depending on the physique of assisted person M, a certain gap may occur between the side of assisted person M and side support portion  42 . As described above, in the initial state where preparation for the boarding in assistive apparatus  1  is finished, assisted person M is placed in a posture in which the upper half body is tilted forward to some extent, as illustrated in  FIG. 2 . 
     Subsequently, when assisted person M or the assisting person presses standing button  63  of controller  60  to input the assistance request for the standing operation, control device  70  executes the first step of changing assisted person M from the initial sitting posture to the intermediate posture in which the upper half body is tilted forward, as illustrated in  FIG. 7  (S 10 ). Specifically, control device  70  first determines whether second arm  22  is located at revolving end on rear side of movable range Rm 2  (S 11 ). Control device  70  acquires the revolving position of second arm  22  and performs the above-described determination, for example, based on the operation state of second actuator  32  of driving device  30 . 
     In a case where second arm  22  is located ahead of the revolving end on rear side of movable range Rm 2  (S 11 : No), control device  70  causes first arm  21  to revolve forward and causes second arm  22  to revolve rearward (S 12 ). As a result, control device  70  advances support member  40  with respect to base  10 , and maintains or lowers the height of support member  40  with respect to base  10 . 
     On the other hand, in a case where second arm  22  is located at the revolving end on rear side of movable range Rm 2  (S 11 : Yes), since the rearward revolving of second arm  22  is restricted, control device  70  causes first arm  21  to revolve forward in a state where second arm  22  is stopped with respect to second center axis  22 A (S 13 ). As a result, control device  70  advances support member  40  with respect to base  10 . 
     Subsequently, control device  70  determines whether first arm  21  is less than a predetermined angle (S 14 ). Control device  70  acquires the revolving position of first arm  21  and performs the above-described determination, for example, based on the operation state of first actuator  31  of driving device  30 . In a case where first arm  21  is less than the predetermined angle (S 14 : No), control device  70  repeats the above-described processing (S 11  to S 13 ). 
     As a result, for example, in a case where second arm  22  reaches the revolving end on rear side of movable range Rm 2  before first arm  21  reaches the predetermined angle, first arm  21  is revolved forward in a state where the rearward revolving of second arm  22  is stopped. In addition, in a case where first arm  21  reaches the predetermined angle (S 14 : Yes), assuming that assisted person M shifts to the intermediate posture, control device  70  ends the first step (S 10 ), and shifts to the execution of the second step (S 20 ). 
     Here, in the first step, when first arm  21  is revolved forward, second center axis  22 A moves forward with respect to base  10  and moves upward. At this time, control device  70  controls the rearward revolving of second arm  22  with respect to the forward revolving of first arm  21  so that the angle of support member  40  is maintained. At this time, since the mass of the upper half body of assisted person M is gradually placed on support member  40  in the first step, the angle of support member  40  is preferably controlled so as to be maintained or tilted forward. 
     According to the control as described above, the amount of change (θ 12 -θ 11 ) of first angles θ 11  and θ 12  formed by the horizontal axis and first virtual line ML 1  before and after the execution of the forward revolving of first arm  21  is equal to or less than the amount of change (θ 22 -θ 21 ) of second angles θ 21  and θ 22  formed by first virtual line ML 1  and second virtual line ML  2  before and after the execution of the rearward revolving of second arm  22 . First angle θ 12  after the execution of the first step corresponds to the predetermined angle of first arm  21 . 
     In addition, angles θ 31  and θ 32  of support member  40  before and after the execution of the first step are maintained or slightly increased (θ 31 ≤θ 32 ). Furthermore, in the first step, each of upward movement amounts BV 1  and UV 1  of lower reference position Pb and upper reference position Pu sets in support member  40  is approximately 0. In addition, in the first step, lower reference position Pb and upper reference position Pu advance by advance amounts BH 1  and UH 1 . 
     As a result, in the first step, assisted person M supported by support member  40  is placed in the intermediate posture (refer to  FIG. 3 ) in which the upper half body of assisted person M is tilted forward from the initial sitting posture (refer to  FIG. 2 ). At this time, lower reference position Pb moves along first movement trajectory Tb from position Pb 1  to position Pb 2 , as illustrated in  FIG. 5 . Similarly, upper reference position Pu moves along second movement trajectory Tu from position Pu 1  to position Pu 2 . As described above, the operation of bending a waist portion so as to shift from the sitting posture to the intermediate posture as the first stage of the standing operation is a natural operation close to the operation in which assisted person M places weight on support member  40  while bending the waist portion by himself. 
     Subsequently, the operation processing of the standing operation is continued, and control device  70  executes the second step (S 20 ) of causing first arm  21  and second arm  22  to revolve forward to change assisted person M from the intermediate posture to the standing posture. Specifically, control device  70  continues the forward revolving of first arm  21 , and switches the operation of second arm  22  from the rearward revolving or the stopped state to the forward revolving. 
     In a case where first arm  21  does not reach a revolving end on front side of movable range Rm 1  (S 22 : No), control device  70  maintains the forward revolving of first arm  21 . On the other hand, in a case where first arm  21  reaches the revolving end on front side of movable range Rm 1  (S 22 : Yes), control device  70  stops the forward revolving of first arm  21  (S 23 ). Similarly, in a case where second arm  22  does not reach the revolving end on front side of movable range Rm 2  (S 24 : No), control device  70  maintains the forward revolving of second arm  22 . On the other hand, in a case where second arm  22  reaches the revolving end on front side of movable range Rm 2  (S 24 : Yes), control device  70  stops the forward revolving of second arm  22  (S 25 ). 
     According to the control as described above, control device  70  controls driving device  30  so that first arm  21  and second arm  22  both revolve forward at the initial stage of the second step (S 20 ). By executing the second step, lower reference position Pb and upper reference position Pu set in support member  40  rise only by upward movement amounts BV 2  and UV 2 , and advance only by advance amounts BH 2  and UH 2 . As a result, in the second step, assisted person M supported by support member  40  is to be placed in a standing posture (refer to  FIG. 4 ) with both legs Mg of assisted person M extended from the intermediate posture (refer to  FIG. 3 ). 
     At this time, lower reference position Pb moves along first movement trajectory Tb from position Pb 2  to position Pb 3 , as illustrated in  FIG. 5 . Similarly, upper reference position Pu moves along second movement trajectory Tu from position Pu 2  to position Pu 3 . As a result, the upper half body of assisted person M advances while lifting from the intermediate posture. Accordingly, in the second step, the state where the back muscle of assisted person M is extended is maintained. In addition, the upper half body of assisted person M is stably supported by support member  40 . 
     Position Pb 3  reached by lower reference position Pb at the end of the second step may appropriately change on first movement trajectory Tb. For example, in a case where the assistance request is no longer inputted to assistive apparatus  1 , control device  70  ends the operation processing of the standing operation. Therefore, depending on lower reference position Pb (position Pb 3 ) at the end, assisted person M in the standing posture may be placed in a state where, for example, the knee is not in contact with knee pad member  80 , in addition to the posture illustrated in  FIG. 4 . This also applies to the relationship between upper reference position Pu and position Pu 3 . 
     4. Effects by Configuration of Embodiment 
     The assistive apparatus  1  according to the embodiment is provided with base  10  on which both legs Mg of assisted person M are placed, first arm  21  revolved around horizontal first center axis  21 A, second arm  22  revolved around horizontal second center axis  22 A, support member  40  supporting the upper half body of assisted person M, and driving device  30  revolving first arm  21  and second arm  22 . In addition, first arm  21  is configured so that second center axis  22 A is located behind first center axis  21 A in the initial state and is located ahead of knee bending position PKb at which upper thigh portion Mh and lower thigh portion Me of assisted person M bend. 
     In addition, the operation processing of assisting the standing operation includes the first step (S 10 ) of causing first arm  21  to revolve forward and causing second arm  22  to revolve rearward (S 12 ) or stop (S 13 ) so that assisted person M supported by support member  40  is placed in the intermediate posture in which the upper half body is tilted forward from the initial sitting posture, and the second step (S 20 ) of causing first arm  21  and second arm  22  to revolve forward (S 21 ) so that assisted person M is placed in the standing posture from the intermediate posture. 
     With the above configuration, support member  40  can be moved along predetermined movement trajectories Td and Tu by first arm  21  and second arm  22  constituting the mechanism having two joints with respect to base  10 . As a result, assistive apparatus  1  can assist the standing operation of assisted person M. In addition, driving device  30  has a configuration for causing the revolving of first arm  21  and the revolving of second arm  22  to cooperate with each other, so that it is possible to downsize assistive apparatus  1  and reduce the manufacturing cost as compared with a configuration including a linear motion device or three or more rotating devices. 
     5. Modified Aspect of Embodiment 
     In the embodiment, the reference position is set at a lower end or an upper end of the portion of trunk support portion  41  in contact with the trunk of assisted person M, or a position of a side of assisted person M. On the other hand, the reference position can be set at an appropriate position when the reference position is set at a position moving integrally with support member  40 . For example, the reference position may be set at the position of the chest portion Mb of assisted person M in a configuration in which support member  40  is provided with the trunk support portion as illustrated in the embodiment. In addition, the reference position may be set at a connecting portion between support member  40  and second arm  22 . In such a configuration, the same effect as that of the embodiment is obtained. 
     In addition, the operation processing of the standing operation includes two steps of the first step and the second step executed in series. On the other hand, another step may be appropriately included in the operation processing of the standing operation. For example, the operation processing may include a preparation step for changing assistive apparatus  1  from a current state to an initial state, a recovery step in a case where each step once executed is stopped and then restarted, and the like. Control device  70  may be configured to control the movement of support member  40  by combining various steps and cooperating the revolving of first arm  21  and the revolving of second arm  22 , based on these operation states of assistive apparatus  1  and the assistance request or the adjustment request to be inputted. 
     Although the first step and the second step are defined as described above in the embodiment, the steps may be classified by the angles of first arm  21  and second arm  22 , the position of lower reference position Pb in first movement trajectory Tb, the position of upper reference position Pu in second movement trajectory Tu, the angle of support member  40 , the posture of assisted person M, or the like. In either classification, in the step of shifting from the sitting posture to the intermediate posture, the same effect as that of the embodiment can be obtained by causing first arm  21  to revolve forward while causing second arm  22  to revolve rearward (stopping in a case of reaching the revolving end on rear side of movable range Rm 2 ). 
     REFERENCE SIGNS LIST 
     
         
           1 : assistive apparatus,  10 : base,  21 : first arm,  22 : second arm,  21 A: first center axis,  22 A: second center axis,  30 : driving device,  31 : first actuator,  32 : second actuator,  40 : support member,  41 : trunk support portion,  42 : side support portion,  60 : controller,  70 : control device,  80 : knee pad member, M: assisted person, Mt: buttocks, Mg: both legs, Mh: upper thigh portion, Me: lower thigh portion, NL 1 : upper thigh virtual line, NL 2 : lower thigh virtual line, ML 1 : first virtual line, ML 2 : second virtual line, Rm 1 , Rm 2 : movable range, PKb: knee bending position, Pb, Pu: reference position