Patent Publication Number: US-2022218499-A1

Title: Motion assistance apparatus and method of controlling the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of Korean Patent Application No. 10-2014-0093831, filed on Jul. 24, 2014, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Example embodiments relate to a motion assistance apparatus and a method of controlling the same. 
     2. Description of the Related Art 
     With the onset of rapidly aging societies, an increased number of people may experience inconvenience and/or agony from joint problems, and, therefore, interest in motion assistance apparatuses that may enable the elderly or patients with joint problems to walk with less effort is growing. In addition, motion assistance apparatuses that may increase muscular strength of human bodies may be in development for military purposes. 
     In general, motion assistance apparatuses for assisting motion of lower parts of bodies may include body frames disposed on trunks of users, pelvic frames coupled to lower sides of the body frames to cover pelvises of the users, femoral frames disposed on thighs of the users, sural frames disposed on calves of the users, and/or pedial frames disposed on feet of the users. The pelvic frames and femoral frames may be connected rotatably by hip joint portions, the femoral frames and sural frames may be connected rotatably by knee joint portions, and/or the sural frames and pedial frames may be connected rotatably by ankle joint portions. 
     The motion assistance apparatuses may include active joint structures including hydraulic systems and/or driving motors to drive each joint portion to improve muscular strength of legs of the users. For example, a motor to transmit driving power may be provided at each of the hip joint portions. 
     SUMMARY 
     Some example embodiments relate to a motion assistance apparatus. 
     In some example embodiments, the motion assistance apparatus may include a first fixing member to be fixed to a portion of a user, a second fixing member to be fixed to another portion of the user, a driving source provided in the first fixing member, a power transmitting member connected between the driving source and the second fixing member, a sensing portion configured to sense a fixing state of the first fixing member or the second fixing member, and a controller configured to control the driving source based on information received from the sensing portion. 
     At least one of the first fixing member and the second fixing member may include a first fixing portion and a second fixing portion to be fastened to or separated from each other. 
     The sensing portion may include a first conductor and a second conductor disposed in the first fixing portion and the second fixing portion, respectively, to be connected or shorted depending on whether the first fixing portion is fastened to the second fixing portion, and the controller may control the driving source based on information about a current flowing between the first conductor and the second conductor. 
     An elastic member may be disposed on one side of one of the first conductor and the second conductor to provide elastic force in a direction in which another of the first conductor and the second conductor is disposed. 
     The first fixing portion and the second fixing portion may have faces facing each other and provided detachably, the sensing portion may include a first conductor and a second conductor disposed in the first fixing portion and the second fixing portion, respectively, and the controller may control the driving source based on information about a capacitance between the first conductor and the second conductor. 
     The first fixing portion and the second fixing portion may be detachably provided in a form of a Velcro. 
     The sensing portion may include a switch disposed in one of the first fixing portion and the second fixing portion to be selectively powered on or off based on whether the first fixing portion is fastened to the second fixing portion. 
     The sensing portion may measure a fastening strength of at least one of the first fixing member and the second fixing member. 
     The sensing portion may include a pressure sensor configured to measure a pressure applied between the user and at least one of the first fixing member and the second fixing member. 
     The sensing portion may include a tensile force sensor configured to measure a tensile force applied to at least one of the first fixing member and the second fixing member. 
     The sensing portion may include a tensile force sensor disposed on the power transmitting member. 
     The sensing portion may include a pressure sensor disposed between the power transmitting member and the second fixing member. 
     Other example embodiments relate to a method of controlling a motion assistance apparatus. 
     In some example embodiments, the motion assistance apparatus may include a main fixing member to be fixed to a portion of a user, an action side fixing member to be fixed to another portion of the user, a driving source provided on the main fixing member, a power transmitting member connected between the driving source and the action side fixing member, and a controller configured to control the driving source. Further, the method may include performing, by the controller, a motion assistance operation for the user based on a fixing state of at least one of the main fixing member and the action side fixing member. 
     The performing may be conducted when both the main fixing member and the action side fixing member are fixed. 
     The performing may include reducing power to be transmitted to the action side fixing member when the main fixing member is unfixed. 
     A plurality of action side fixing members may be provided, and the performing may include sensing respective fixing states of the plurality of action side fixing members, and reducing power to be transmitted to a portion of the plurality of action side fixing members when the portion of the plurality of action side fixing members is unfixed. 
     The performing may include controlling power to be transmitted to the action side fixing member based on a direction of a load applied to the action side fixing member, and the controlling may include continuously performing the motion assistance operation for the user when the load is applied in a direction in which the action side fixing member is pushed, and reducing power to be transmitted to the action side fixing member when the load is applied in a direction in which the action side fixing member is pulled. 
     The reducing may include stopping the driving source, or reducing an output of the driving source to a predetermined output value. 
     Other example embodiments relate to a method of controlling a motion assistance apparatus. 
     In some example embodiments, the motion assistance apparatus may include a driving source, a main fixing member to be fixed to a portion of a user, an action side fixing member to be fixed to a leg of the user, a power transmitting member configured to transmit power between the driving source and the action side fixing member, and a controller configured to control the driving source. Further, the method may include performing, by the controller, a motion assistance operation for the user based on a fixing state of the action side fixing member. 
     The performing may include reducing power to be transmitted to the action side fixing member when the action side fixing member is unfixed and both legs of the user are in contact with the ground. 
     The performing may include sensing whether the user is walking in an upward inclined direction or in a downward inclined direction, and transmitting power until both legs of the user are in contact with the ground when the user is walking in a downward inclined direction and the action side fixing member is unfixed. 
     The performing may include sensing whether the user is walking in an upward inclined direction or in a downward inclined direction, and reducing power to be transmitted to the action side fixing member when the user is walking in an upward inclined direction and the action side fixing member is unfixed. 
     The performing may include sensing whether a function of the action side fixing member corresponds to a moving function or a supporting function when the action side fixing member is unfixed, and reducing power to be transmitted to the unfixed action side fixing member when the function of the unfixed action side fixing member corresponds to the moving function. 
     The performing may further include transmitting power until the function of the unfixed action side fixing member is changed to the moving function when the function of the unfixed action side fixing member corresponds to the supporting function. 
     Some example embodiments relate to a motion assistance apparatus configured to assist a user with walking. 
     In some example embodiments, the motion assistance apparatus may include a belt having a first end and a second end, the belt configured to attach to a waist of the user by connecting the first end and the second end; a thigh cuff configured to attach to a thigh of the user; a power transmitting member configured to transmit a torque to the thigh cuff; and a controller including processor and a memory, the memory containing computer readable code that, when executed by the processor, configures the controller to, determine if one or more of the belt and the thigh cuff are secured to the waist and the thigh of the user, respectively, and instruct a driving source to perform a motion assistance operation based on whether the one or more of the belt and the thigh cuff are secured, the motion assistance operation being an operation in which a force generated by the driving source is transmitted to the joint assembly. 
     In some example embodiments, the motion assistance apparatus includes one or more sensors configured to sense whether one or more of the belt and the thigh cuff are secured, wherein the controller is configured to determine if one or more of the belt and the thigh cuff become unsecured during the motion assistance operation based on signals received from the one or more sensors. 
     In some example embodiments, the controller is configured to reduce the power based on a walking state, if the controller determines that one or more of the belt and the thigh cuff have become unsecured during the motion assistance operation. 
     In some example embodiments, the walking state includes an incline walking state and a decline walking state, and the controller is configured to reduce the power when one or more of the belt and the thigh cuff have become unsecured during the motion assistance operation irrespective of whether feet of the user are in contact with a ground, if the walking state is the incline walking state. 
     In some example embodiments, the controller is configured to stop transmitting the power when one or more of the belt and the thigh cuff have become unsecured during the motion assistance operation and the controller has determined that the user has come to rest. 
     In some example embodiments, the controller is configured to continue to perform the motion assistance operation on a leg of the user when one or more of the belt and the thigh cuff have become unsecured, if the motion assistance device is exerting positive work on the leg of the user. 
     Additional aspects of example embodiments will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects will become apparent and more readily appreciated from the following description of example embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a front view illustrating a motion assistance apparatus being worn on a user according to some example embodiments; 
         FIG. 2  is a side view illustrating a motion assistance apparatus being worn on a user according to example embodiments; 
         FIG. 3  is a view illustrating a sensing portion according to some example embodiments; 
         FIG. 4  is a view illustrating a sensing portion according to some example embodiments; 
         FIG. 5  is a view illustrating a sensing portion according to some example embodiments; 
         FIG. 6  is a view illustrating a sensing portion according to some example embodiments; 
         FIG. 7  is a view illustrating a sensing portion according to some example embodiments; 
         FIG. 8  is a view illustrating a sensing portion according to some example embodiments; 
         FIG. 9  is a block diagram illustrating a motion assistance apparatus according to some example embodiments; 
         FIG. 10  is a flowchart illustrating a method of controlling a motion assistance apparatus according to some example embodiments; 
         FIG. 11  is a flowchart illustrating a method of controlling a motion assistance apparatus according to some example embodiments; 
         FIG. 12  is a flowchart illustrating a method of controlling a motion assistance apparatus according to some example embodiments; 
         FIG. 13  is a flowchart illustrating a method of controlling a motion assistance apparatus, performed based on a type of an unfixed fixing member, according to some example embodiments; 
         FIG. 14  is a flowchart illustrating a method of controlling a motion assistance apparatus, performed based on a walking situation of a user, according to some example embodiments; 
         FIG. 15  is a flowchart illustrating a method of controlling a motion assistance apparatus, performed based on a function of an unfixed fixing member, according to some example embodiments; 
         FIG. 16  is a flowchart illustrating a method of controlling a motion assistance apparatus, performed based on a direction of a load applied to an unfixed fixing member, according to some example embodiments; 
         FIG. 17  is a flowchart illustrating an operation of reducing power to be transmitted to an action side fixing member in a method of controlling a motion assistance apparatus according to some example embodiments; and 
         FIG. 18  illustrates a controller according to some example embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to example embodiments, some examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. Example embodiments are described below with reference to the figures. 
       FIG. 1  is a front view illustrating a motion assistance apparatus  10  being worn on a user  1  according to some example embodiments, and  FIG. 2  is a side view illustrating the motion assistance apparatus  10  being worn on the user  1  according to some example embodiments. 
     Referring to  FIGS. 1 and 2 , the motion assistance apparatus  10  may be worn on the user  1  to assist a motion of the user  1 . The user  1  may correspond to a human, an animal, or a robot. However, the user  1  is not limited thereto. In addition, although  FIGS. 1 and 2  illustrate a case in which the motion assistance apparatus  10  assists a motion of a thigh of the user  1 , the motion assistance apparatus  10  may also assist the user with motion an upper body part, for example, a hand, an upper arm, and a lower arm of the user  1 , or motion of another lower body part, for example, a foot, and a calf of the user  1 . The motion assistance apparatus  10  may assist a motion of a part of the user  1 . For example, in other example embodiments, the driving source  30  may be provided at the knee joint of the user  1  and the second fixing member  60  may be configured to attach to the shin of the user  1  to transmit a driving force to the shin of the user  1 . Hereinafter, a case in which the motion assistance apparatus  10  assists a motion of a thigh of a human will be described, however, example embodiments are not limited thereto. 
     The motion assistance apparatus  10  includes a first fixing member  20 , a driving source  30 , a power transmitting member  50 , a second fixing member  60 , a controller  70 , and a sensing portion  100 . 
     The first fixing member  20  may be fixed to a portion of the user  1 . The first fixing member  20  may be in contact with at least a portion of an outer surface of the user  1 . The first fixing member  20  may be configured to cover the portion of the outer surface of the user  1 . The first fixing member  20  may be provided to be curved in a shape corresponding to a contact portion of the user  1 . The first fixing member  20  may include a curved surface to be in contact with the user  1 . For example, the first fixing member  20  may be fixed to one side of a waist of the user  1 . The first fixing member  20  may be referred to as a “waist fixing member”. The first fixing member  20  may also be referred to as a “main fixing member”. 
     The driving source  30  may be provided to the first fixing member  20 . The driving source  30  may provide power to be transmitted to the power transmitting member  50 . For example, a plurality of driving sources may be provided. The driving sources  30  may be provided on both sides of the first fixing member  20 , respectively. However, a number or positions of the driving sources  30  is not limited thereto. 
     The power transmitting member  50  may be connected between the driving source  30  and the second fixing member  60 . The power transmitting member  50  may transmit power received from the driving source  30  to the second fixing member  60 . The power transmitting member  50  may be, for example, a frame, a wire, a cable, a string, a rubber band, a spring, a belt, and a chain. However, the power transmitting member  50  is not limited thereto. 
     The second fixing member  60  may be fixed to another portion of the user  1 . For example, the second fixing member  60  may be fixed to one side of a leg of the user  1 . The second fixing member  60  may be referred to as a “leg fixing member”. The second fixing member  60  may be disposed to cover a circumference of at least a portion of the thigh of the user  1  to apply power received from the power transmitting member  50  to the thigh of the user  1 . 
     A plurality of second fixing members  60  may be provided. The plurality of second fixing members  60  may be fixed to both legs of the user  1 , respectively. The plurality of second fixing members  60  may respectively rotate with respect to the first fixing member  20 . The first fixing member  20  may be referred to as the “main fixing member”, and the second fixing member  60  may also be referred to as an “action side fixing member”. In the action side fixing member, a fixing member to be fixed to one leg of the user  1  may be referred to as a “first action side fixing member”, and a fixing member to be fixed to the other leg of the user  1  may be referred to as a “second action side fixing member”. 
     The controller  70  may control the driving source  30  based on information received from the sensing portion  100 . 
     The sensing portion  100  may sense a fixing state of the first fixing member  20  or the second fixing member  60 . For example, the sensing portion  100  may be connected to at least one of the first fixing member  20  and the second fixing member  60 . Hereinafter, the sensing portion  100  will be described in detail. 
       FIG. 3  is a view illustrating the sensing portion  100  according to some example embodiments. 
     Referring to  FIG. 3 , the sensing portion  100  may be provided in at least one of the first fixing member  20  and the second fixing member  60 . Hereinafter, a case in which the sensing portion  100  is provided in the first fixing member  20  will be described. However, example embodiments are not limited thereto. 
     The first fixing member  20  includes a first fixing portion  110  and a second fixing portion  120  to be fastened to or separated from each other. For example, the first fixing portion  110  and the second fixing portion  120  may be detachably provided in a structure of a buckle. The second fixing portion  120  may include an insertion portion, and the first fixing portion  110  may include a hanging portion to be releasably inserted into the insertion portion and locked in place by two resilient opposed lateral arms extending away from a center of the insertion portion. The arms may compress upon insertion, thereby providing a spring loading potential energy for their outward expansion. The arms may move into locking slots on the body of the first insertion portion  110  upon full insertion of the insertion portion and spring out into the locked position within the slot. 
     The sensing portion  100  may include a first conductor  130  and a second conductor  140 . The first conductor  130  and the second conductor  140  may be disposed in the first fixing portion  110  and the second fixing portion  120 , respectively. The first conductor  130  and the second conductor  140  may be connected to or shorted from each other based on whether the first fixing portion  110  is fastened to the second fixing portion  120 . 
     One side of the first conductor  130  may be connected to the controller  70  with a first wire  132 , and another side of the first conductor  130  may be selectively connected to or shorted from the second conductor  140 . One side of the second conductor  140  may be connected to the controller  70  with a second wire  142 , and another side of the second conductor  140  may be selectively connected to or shorted from the first conductor  130 . The first wire  132  and the second wire  142  may be embedded in an internal portion of the first fixing member  20  and, therefore, damage to the first wire  132  and the second wire  142  by an external impact may be prevented. 
     The sensing portion  100  may further include an elastic member  150 . The elastic member  150  may be disposed on one of the first conductor  130  and the second conductor  140 . The elastic member  150  may provide elastic force in a direction in which one of the first conductor  130  and the second conductor  140  is disposed with respect to another of the first conductor  130  and the second conductor  140 . 
     The controller  70  may control the driving source  30  based on information about a current flowing between the first conductor  130  and the second conductor  140 . For example, when a current flows between the first conductor  130  and the second conductor  140 , the controller  70  may determine that the first fixing member  20  is fixed. Thus, the controller  70  may power on the driving source  30 . Conversely, when a current does not flow between the first conductor  130  and the second conductor  140 , the controller  70  may determine that the first fixing member  20  is unfixed. Thus, the controller  70  may power off the driving source  30 . 
     Hereinafter, the same name may be used to describe an element included in the example embodiments described above and an element having a common function. Unless otherwise mentioned, the descriptions on the example embodiments may be applicable to the following example embodiments and thus, duplicated descriptions will be omitted for conciseness. 
       FIG. 4  is a view illustrating a sensing portion  200  according to some example embodiments. 
     Referring to  FIG. 4 , the sensing portion  200  may be provided in at least one of the first fixing member  20  and the second fixing member  60 . Hereinafter, a case in which the sensing portion  200  is provided in the first fixing member  20  will be described. The first fixing member  20  includes a first fixing portion  210  and a second fixing portion  220  to be fastened to or separated from each other. The first fixing portion  210  and the second fixing portion  220  may have faces facing each other and provided detachably. For example, the first fixing portion  210  and the second fixing portion  220  may be detachably provided in a form of a hook and loop fastener. 
     The sensing portion  200  may include a first conductor  230  and a second conductor  240 . The first conductor  230  and the second conductor  240  may be disposed in the first fixing portion  210  and the second fixing portion  220 , respectively. The first conductor  230  and the second conductor  240  may be disposed in an internal portion of the first fixing portion  210  and an internal portion of the second fixing portion  220 , respectively, therefore, damage to the first conductor  230  and the second conductor  240  by an external impact may be prevented. 
     One side of the first conductor  230  may be connected to the controller  70  with a first wire  232 . One side of the second conductor  240  may be connected to the controller  70  with a second wire  242 . The first wire  232  and the second wire  242  may be embedded in an internal portion of the first fixing member  20 . 
     A capacitance C between the first conductor  230  and the second conductor  240  may be expressed by Equation 1. 
     
       
         
           
             
               
                 
                   C 
                   = 
                   
                     ϵ 
                     ⁢ 
                     
                       A 
                       d 
                     
                   
                 
               
               
                 
                   [ 
                   
                     Equation 
                     ⁢ 
                        
                     1 
                   
                   ] 
                 
               
             
           
         
       
     
     In Equation 1, ε denotes a permittivity of a substance between the first conductor  230  and the second conductor  240 . A denotes an overlapping area of the first conductor  230  and the second conductor  240  in a vertical direction and d denotes a vertical distance between the first conductor  230  and the second conductor  240 . 
     The distance d may change based on a vertical distance between the first fixing portion  210  and the second fixing portion  220 . According to Equation 1, the capacitance C may increase as the distance between the first fixing portion  210  and the second fixing portion  220  decreases. For example, the distance d may be minimized when the first fixing portion  210  and the second fixing portion  220  are attached to each other. Therefore, the capacitance C may be maximum when the first and second fixing portions  210 ,  220  are attached. 
     The area A may change based on a difference between a horizontal position of the first fixing portion  210  and a horizontal position of the second fixing portion  220 . According to Equation 1, the capacitance C may increase as the overlapping area of the first fixing portion  210  and the second fixing portion  220  increases. For example, the capacitance C may be maximized when the first fixing portion  210  and the second fixing portion  220  completely overlap each other in a vertical direction. 
     The capacitance C may function as an indicator of a fixing force of the first fixing portion  210  and the second fixing portion  220 . Thus, the controller  70  may control the driving source  30  based on information about the capacitance C between the first conductor  230  and the second conductor  240 . When the measured capacitance C is greater than a desired (or, alternatively, a predetermined) reference capacitance C 0 , the controller  70  may determine that the first fixing member  20  is fixed. Thus, the controller  70  may power on the driving source  30 . Conversely, when the measured capacitance C is less than the reference capacitance C 0 , the controller  70  may determine that the first fixing member  20  is unfixed. Thus, the controller  70  may power off the driving source  30 . 
       FIG. 5  is a view illustrating a sensing portion  300  according to some example embodiments. 
     Referring to  FIG. 5 , the sensing portion  300  may be provided in at least one of the first fixing member  20  and the second fixing member  60 . Hereinafter, a case in which the sensing portion  300  is provided in the first fixing member  20  will be described. The first fixing member  20  includes a first fixing portion  310  and a second fixing portion  320  to be fastened to or separated from each other. For example, the first fixing portion  310  and the second fixing portion  320  may be detachably provided in a structure of a buckle. The second fixing portion  320  may include an insertion portion, and the first fixing portion  310  may include a hanging portion to be inserted into the insertion portion. 
     The sensing portion  300  may further include a switch  330  to be selectively powered on or off based on whether the first fixing portion  310  is fastened to the second fixing portion  320 . The switch  330  may be disposed in one of the first fixing portion  310  and the second fixing portion  320 . For example, the switch  330  may be disposed in the second fixing portion  320 , and be pressurized by the first fixing portion  310 . The switch  330  may include a button portion  332 , a first conductor  334 , a second conductor  336 , a third conductor  338 , and an elastic member  339 . 
     The button portion  332  may be provided to move slidingly with respect to the second fixing portion  320 . The first conductor  334  may be disposed on one side of the button portion  332 . The first conductor  334  may selectively connect the second conductor  336  to the third conductor  338  or short the second conductor  336  from the third connector  338  based on whether the first fixing portion  310  is fastened to the second fixing portion  320 . 
     The second conductor  336  and the third conductor  338  may be connected to the controller  70  with a first wire  341  and a second wire  342 , respectively. The first wire  341  and the second wire  342  may be disposed in an internal portion of the first fixing member  20 . 
     The elastic member  339  may provide elastic force in a direction in which the first conductor  334  is disposed apart from the second conductor  336  and the third conductor  338 . 
     The controller  70  may control the driving source  30  based on information about a current flowing between the second conductor  336  and the third conductor  338 . For example, when a current flows between the second conductor  336  and the third conductor  338 , the controller  70  may determine that the first fixing member  20  is fixed. Thus, the controller  70  may power on the driving source  30 . Conversely, when a current does not flow between the second conductor  336  and the third conductor  338 , the controller  70  may determine that the first fixing member  20  is unfixed. Thus, the controller  70  may power off the driving source  30 . 
       FIG. 6  is a view illustrating a sensing portion  400  according to some example embodiments. 
     Referring to  FIG. 6 , the sensing portion  400  may be provided in at least one of the first fixing member  20  and the second fixing member  60 . Hereinafter, a case in which the sensing portion  400  is provided in the first fixing member  20  will be described. The first fixing member  20  may include a first fixing portion  410  and a second fixing portion  420  to be fastened to or separated from each other. 
     The sensing portion  400  may measure a fastening strength of the first fixing member  20 . The sensing portion  400  may include pressure sensors  430  to measure a pressure applied between the first fixing member  20  and the user  1 . The pressure sensors  430  may be provided on an inner side surface of the first fixing member  20 . 
     The controller  70  may control the driving source  30  based on information about the pressure measured by the pressure sensors  430 . For example, when the measured pressure is greater than or equal to a desired (or, alternatively, a predetermined) reference pressure, the controller  70  may determine that the first fixing member  20  is fixed. Thus, the controller  70  may power on the driving source  30 . Conversely, when the measured pressure is less than the reference pressure, the controller  70  may determine that the first fixing member  20  is unfixed. Thus, the controller  70  may power off the driving source  30 . 
       FIG. 7  is a view illustrating a sensing portion  500  according to some example embodiments. 
     Referring to  FIG. 7 , the sensing portion  500  may be provided in at least one of the first fixing member  20  and the second fixing member  60 . Hereinafter, a case in which the sensing portion  500  is provided in the first fixing member  20  will be described. The first fixing member  20  may include a first fixing portion  510  and a second fixing portion  520  to be fastened to or separated from each other. 
     The sensing portion  500  may measure a fastening strength of the first fixing member  20 . The sensing portion  500  may include a tensile force sensor  530  to measure a tensile force applied to the first fixing member  20 . The tensile force sensor  530  may be provided in an internal portion of the first fixing member  20 . For example, the tensile force sensor  530  may include a strain gauge. In other example embodiments, the first fixing member  20  may include an air bladder configured to hold an amount of gas therein to supply uniform pressure to the user  1 , and the tensile force sensor  530  may be configured to sense a fixing state of the first fixing member  20  by sensing a deformation rate of the first fixing member  20 . 
     The controller  70  may control the driving source  30  based on information about the tensile force measured by the tensile force sensor  530 . For example, when the measured tensile force is greater than or equal to a desired (or, alternatively, a predetermined) reference tensile force, the controller  70  may determine that the first fixing member  20  is fixed. Thus, the controller  70  may power on the driving source  30 . Conversely, when the measured tensile force is less than the reference tensile force, the controller  70  may determine that the first fixing member  20  is unfixed. Thus, the controller  70  may power off the driving source  30 . 
       FIG. 8  is a view illustrating a sensing portion  80  according to some example embodiments. 
     Referring to  FIG. 8 , the sensing portion  80  may be disposed in the power transmitting member  50 . The sensing portion  80  may include a tensile force sensor  82  and/or a pressure sensor  84 . 
     The tensile force sensor  82  may measure a tensile force applied to the power transmitting member  50 . The controller  70  may control the driving source  30  based on information on the tensile force measured by the tensile force sensor  82 . The tensile force sensor  82  may operate in a similar manner as the tensile force sensor  530 , and, therefore, detailed descriptions thereof will be omitted for conciseness. 
     The pressure sensor  84  may be disposed between the power transmitting member  50  and the second fixing member  60 . The pressure sensor  84  may measure a pressure applied between the power transmitting member  50  and the second fixing member  60 . The controller  70  may control the driving source  30  based on information about the pressure measured by the pressure sensor  84 . The pressure sensor  84  may operate in a similar manner as the pressure sensor  430 , and, therefore, detailed descriptions thereof will be omitted for conciseness. 
       FIG. 9  is a block diagram illustrating the motion assistance apparatus  10  according to some example embodiments. 
     Referring to  FIG. 9 , the motion assistance apparatus  10  may include the main fixing member  20 , the driving source  30 , the power transmitting unit  50 , the action side fixing member  60 , the controller  70  and the sensing portion  100 . 
     The action side fixing member  60  may include a first action side fixing member and a second action side fixing member that support different portions of the user  1 . 
     The sensing portion  100  includes a main sensing portion to sense a fixing state of the main fixing member  20 , a first action side sensing portion to sense a fixing state of the first action side fixing member, and a second action side sensing portion to sense a fixing state of the second action side fixing member. In some example embodiments, the first and second action side sensing portions may be connected to the first and second active side fixing members, respectively. 
     The power transmitting member  50  may include a first power transmitting member to transmit power to the first action side fixing member, and a second power transmitting member to transmit power to the second action side fixing member. 
     The driving source  30  may include a first driving source to drive the first power transmitting member, and a second driving source to drive the second power transmitting member. The first power transmitting member and the second power transmitting member may also be driven by a single driving source. 
     The controller  70  may control the driving source  30  based on information received from the main sensing portion, the first action side sensing portion, and the second action side sensing portion. The controller  70  will be described in more detail with reference to  FIG. 18 . 
       FIG. 10  is a flowchart illustrating a method of controlling the motion assistance apparatus  10  according to some example embodiments. 
     Referring to  FIG. 10 , in operation  600 , the controller  70  may power on the motion assistance apparatus  10 . In operation  610 , the sensing portion  100  may sense a fixing state of the main fixing member  20  or the action side fixing member  60 . In operation  620 , the controller  70  may perform a motion assistance operation by controlling the driving source  30 . 
     In detail, in operation  600 , the controller  70  may power on the motion assistance apparatus  10  in response to a request by a user. 
     When the motion assistance apparatus  10  is powered on, in operation  610 , the sensing portion  100  may sense a fixing state of the main fixing member  20  and/or the action side fixing member  60 . When the sensing portion  100  includes a pressure sensor, the sensing portion  100  may measure a pressure applied between a user and the main fixing member  20  and/or the action side fixing member  60 , and sense the fixing state of the main fixing member  20  and/or the action side fixing member  60  based on the measured pressure. For example, the sensing portion  100  may include one or more of the sensing portions  100  to  500  described above. 
     When the sensing portion  100  senses that the main fixing member  20  and/or the action side fixing member  60  is unfixed in operation  610 , the controller  70  may instruct the sensing portion  100  to iteratively perform operation  610  to determine when the main fixing member  20  and/or the action side fixing member  60  is fixed. When the main fixing member  20  or the action side fixing member  60  is fixed in operation  610 , in operation  610 , the controller  70  may control the driving source  30  to perform a motion assistance operation. The motion assistance operation may assist the user  1  in smoothly walking. For example, the motion assistance operation may vary an amount of assistance provided to the user  1  as the user  1  moves through various phases of a walking cycle. For example, the controller  70  may instruct the walking assistance robot to increase the torque, if the main fixing member  20  or the action side fixing member  60  is exerting positive work on the leg of the user  1 , for example, when the user  1  is increasing a pace of walking on a flat surface, a sloped surface or a stepped surface. Likewise, the controller  70  may instruct the walking assistance robot to increase a damping torque applied to a leg of the user  1 , if the main fixing member  20  or the action side fixing member  60  is exerting negative work on the leg of the user  1 , for example, when the user  1  is decreasing a pace of walking on the flat surface, the sloped surface or the stepped surface. 
     In the foregoing control method, the motion assistance apparatus  10  may operate while the main fixing member  20  or the action side fixing member  60  is fixed and thus, a user safety may increase. In addition, without receiving a separate motion assistance instruction, the controller may immediate perform the motion assistance operation when the main fixing member  20  or the action side fixing member  60  is sensed as being fixed while the motion assistance apparatus  10  is powered on and thus, a usability may increase. 
       FIG. 11  is a flowchart illustrating a method of controlling the motion assistance apparatus  10  according to some example embodiments. Duplicated descriptions similar to the descriptions provided with reference to  FIG. 10  will be omitted for conciseness. 
     Referring to  FIG. 11 , the method of controlling the motion assistance apparatus  10  illustrated in  FIG. 11  further includes an operation  605  of receiving a motion assistance instruction, as compared to the method of  FIG. 10 . 
     In detail, in operation  600 , the controller  70  may power on the motion assistance apparatus  10  in response to an instruction from a user. 
     When the motion assistance apparatus  10  is powered on, in operation  605 , the controller  70  may receive a motion assistance instruction. 
     The controller  70  may iteratively perform operation  605  until the motion assistance instruction is input into the controller  70 . When the motion assistance instruction is input in operation  605 , in operation  610 , the sensing portion  100  may sense a fixing state of the main fixing member  20  and/or the action side fixing member  60 . 
     When the main fixing member  20  and/or the action side fixing member  60  is unfixed in operation  610 , the controller  70  may instruct the sensing portion  100  to iteratively perform operation  610  to determine when the main fixing member  20  and/or the action side fixing member  60  is fixed. When the main fixing member  20  or the action side fixing member  60  is fixed in operation  610 , the controller  70  may control the driving source  30  to perform a motion assistance operation, in operation  620 . 
     In the foregoing controlling method, operation  620  may be performed after two verifications are performed. The motion assistance apparatus  10  may operate in response to an input of a motion assistance instruction and thus, a user manipulability may increase. In addition, when operation  605  is performed prior to operation  610 , an unnecessary sensing operation of the sensing portion  100  may be prevented until the motion assistance instruction is input. 
     While  FIG. 11  illustrates that the controller  70  performs operation  605  before operation  610 , the controller  70  may perform operation  605  after operation  610  is performed. 
       FIG. 12  is a flowchart illustrating a method of controlling the motion assistance apparatus  10  according to some example embodiments. Duplicated descriptions similar to the descriptions provided with reference to  FIGS. 10 and 11  will be omitted for conciseness. 
     Referring to  FIG. 12 , the method of controlling the motion assistance apparatus  10  further includes operation  610  of primarily sensing a fixing state of the main fixing member  20  or the action side fixing member  60 , operation  612  of secondarily sensing a fixing state of the main fixing member  20  or the action side fixing member  60 , and operation  614  of receiving a motion assistance instruction to be performed after operation  612  is performed. 
     In detail, in operation  610 , the sensing portion  100  may primarily sense a fixing state of the main fixing member  20  and/or the action side fixing member  60 . 
     When the main fixing member  20  or the action side fixing member  60  is sensed as being fixed in operation  610 , the controller  70  may perform a motion assistance operation in operation  620 . In contrast, when the sensing portion  100  senses that the main fixing member  20  or the action side fixing member  60  is unfixed in operation  610 , the controller  70  may perform operation  612 . 
     When the main fixing member  20  or the action side fixing member  60  is sensed as still being unfixed in operation  612 , operation  612  may be iteratively performed. When the main fixing member  20  or the action side fixing member  60  is sensed as being fixed in operation  612 , the controller  70  may perform operation  614 . 
     When the motion assistance instruction is not input in operation  614 , the controller  70  may iteratively perform operation  614 . When the motion assistance instruction is input in operation  614 , the controller  70  may perform a motion assistance operation in operation  620 . 
     Operation  605  of receiving a motion assistance instruction may be performed prior to operation  610 . In some example embodiments, operation  605  may be an operation of primarily receiving a motion assistance instruction, and operation  614  may be an operation of secondarily receiving a motion assistance instruction. 
     In the foregoing control method, the controller  70  may perform a motion assistance operation immediately when the main fixing member  20  or the action side fixing member  60  is sensed as being fixed in operation  610  and thus, usability may increase. In addition, if the controller  70  senses that the main fixing member  20  and/or the action side fixing member  60  is unfixed in operation  610 , by preventing an automatic operation of the motion assistance apparatus  10  until a motion assistance instruction is input, the controller  70  may secure a sufficient time to fix the main fixing member  20  or the action side fixing member  60 , and, therefore, a user safety may increase. 
       FIG. 13  is a flowchart illustrating a method of controlling the motion assistance apparatus  10 , performed based on a type of an unfixed fixing member, according to some example embodiments. 
     Referring to  FIG. 13 ,  FIG. 13  illustrates performing motion assistance as illustrated in operation  620  of  FIGS. 10-12  according to some example embodiments, in which the motion assistance is based on a type of an unfixed fixing member. 
     The motion assistance of operation  620  may include operation  630  of sensing whether the main fixing member  20  is fixed, operation  632  of sensing whether the action side fixing member  60  is fixed, operation  633  of reducing power to be transmitted to the unfixed action side fixing member  60 , and operation  631  of reducing power to be transmitted to all action side fixing members  60 . 
     In detail, in operation  630 , the main sensing portion of the sensing portion  100  may sense whether the main fixing member  20  is fixed. 
     When the main fixing member  20  is sensed as being unfixed in operation  630 , the controller  70  may control the driving source  30  to reduce power to be transmitted to all action side fixing members  60 , in operation  631 . When the main fixing member  20  is sensed as being fixed in operation  630 , the action side sensing portion of the sensing potion  100  may sense whether the action side fixing member  60  is fixed, in operation  632 . 
     When all action side fixing members  60  are sensed as being fixed in operation  632 , the controller  70  may iteratively instruct the main sensing portion of the sensing portion  100  to iteratively perform operation  630  and monitor whether the main fixing member  20  remains fixed. 
     When a portion of action side fixing members  60  are sensed as being unfixed in operation  632 , the controller  70  may control the driving source  30  to reduce power to be transmitted to the unfixed action side fixing member  60 , in operation  633 . When all action side fixing members  60  are sensed as being unfixed in operation  632 , the controller  70  may control the driving source  30  to reduce power to be transmitted to all the action side fixing members  60 , in operation  631 . 
     In the foregoing controlling method, the controller  70  may suspend a motion assistance operation when the main fixing member  20  is unfixed and thus, a user safety may increase. Further, when a portion of the action side fixing members  60  is unfixed while the main fixing member  20  is fixed, by reducing only power to be transmitted to the unfixed action side fixing member  60 , a remaining fixed action side fixing member  40  may continuously perform the motion assistance operation. Therefore, even if a part of the motion assistance apparatus  10  malfunctions, the motion assistance apparatus  10  may continuously operate within a safety-secured range. Thus, a usage efficiency of the motion assistance apparatus  10  may increase. 
       FIG. 14  is a flowchart illustrating a method of controlling the motion assistance apparatus  10 , performed based on a walking situation of a user, according to some example embodiments. 
     Referring to  FIG. 14 ,  FIG. 14  illustrates performing motion assistance as illustrated in operation  620  of  FIGS. 10-12  according to some example embodiments in which the motion assistance is based on a walking situation of a user. 
     The motion assistance of operation  620  may include operation  640  of sensing a fixing state of the main fixing member  20  or the action side fixing member  60 , operation  641  of sensing a walking situation of a user, operation  642  of sensing whether both feet of the user are in contact with the ground, and operation  643  of reducing power to be transmitted to the action side fixing member  60 . For example, in some example embodiments, in an effort to avoid injury to the user  1 , even though the fixing member  60  is unfastened, the motion assistance apparatus  10  may continue to perform the aforementioned motion assistance operation when the user  1  is walking downhill and has not stopped and placed both feet on the ground. Therefore, although the fixing member  60  is unfastened while the user is walking downhill, the power transmitting member  50  may prevent a sudden forward jerk of the leg of the user  1 . 
     In detail, in operation  640 , the sensing portion  100  may sense whether the main fixing member  20  and/or the action side fixing member is fixed. 
     When the main fixing member  20  or the action side fixing member is sensed as being unfixed in operation  640 , the controller  70  may sense a walking situation of the user, in operation  641 . 
     The walking situation of the user may include a situation in which the user is walking on a slope or stairs in an upward inclined direction, hereinafter referred to as “walking upward”, and a situation in which the user is walking on a slop or stairs in a downward inclined direction, hereinafter referred to as a “walking downward”. The walking situation may be sensed using an altimeter, an accelerometer, or a motion pattern obtained based on, for example, an angle of rotation of the power transmitting member  50 . 
     When the controller  70  senses that the user is walking upward in operation  641 , the controller  70  may reduce the power transmitted to the action side fixing member  60 , in operation  643 . 
     When the controller  70  senses that user is walking downward in operation  641 , the controller  70  may determine whether both feet of the user are in contact with the ground, in operation  642 . Whether a foot of the user is in contact with the ground may be sensed using a pressure sensor, an inertial measurement unit, or an acceleration sensor disposed on the foot of the user. When a pressure measured by the pressure sensor increases beyond a threshold, the controller  70  may sense that the foot of the user is in contact with the ground. In addition, an oscillation occurring when the foot touches the ground may be sensed using an inertial measurement unit or an acceleration sensor. 
     When both feet of the user are sensed as being not in contact with the ground in operation  642 , the controller  70  may iteratively perform operation  642  until both feet of the user contact the ground. When both feet of the user are sensed as being in contact with the ground in operation  642 , the controller  70  may reduce the power transmitted to the action side fixing member  60 , in operation  643 . 
     While  FIG. 14  illustrates operation  642  being performed after operation  641 , in some example embodiments, operation  642  may also be performed prior to operation  641  such that, when both feet of the user are in contact with the ground, the controller  70  may reduce the transmitted power in operation  643  immediately without first sensing the walking situation of the user. 
     In the foregoing control method, in a case of walking downward, which is more dangerous than walking upward, the controller  70  may reduce the assistance power when both feet are in contact with the ground. Thus, an accident happening to the user due to a sudden change in power may be prevented. 
       FIG. 15  is a flowchart illustrating a method of controlling the motion assistance apparatus  10 , performed based on a function of an unfixed fixing member, according to some example embodiments. 
     Referring to  FIG. 15 ,  FIG. 15  illustrates performing motion assistance as illustrated in operation  620  of  FIGS. 10-12  according to some example embodiments in which the motion assistance is based on a function of an unfixed fixing member. 
     In some example embodiments, the motion assistance of operation  620  may include operation  650  of sensing a fixing state of the main fixing member  20  or the action side fixing member  60 , operation  651  of sensing a function of the unfixed action side fixing member  60 , operation  652  of sensing whether the function of the unfixed action side fixing member  60  is changed to a moving function, operation  654  of sensing whether both feet of the user are in contact with the ground, and operation  653  of reducing power to be transmitted to the action side fixing member  60 . 
     In detail, in operation  650 , the sensing portion  100  may sense a fixing state of the main fixing member  20  and/or the action side fixing member  60 . 
     The controller  70  may instruct the sensing portion  100  to iteratively perform operation  650  until one or more of the main fixing member  20  and the action side fixing member  60  is sensed as being unfixed. 
     When the main fixing member  20  or the action side fixing member  60  is sensed as being unfixed in operation  650 , the controller  70  may sense a function of the unfixed action side fixing member  60 , in operation  651 . 
     The function of the action side fixing member  60  may include a moving function and a supporting function. The moving function may refer to a function of the action side fixing member  60  corresponding to a leg spaced apart from the ground. The supporting function may refer to a function of the action side fixing member  60  corresponding to a leg being in contact with the ground. The function of the action side fixing member  60  may be sensed using a pressure sensor, an inertial measurement unit, or an acceleration sensor disposed on a foot of the user. 
     When the function of the unfixed action side fixing member  60  corresponds to the moving function in operation  651 , the controller  70  may reduce power transmitted to the unfixed action side fixing member  60 , in operation  653 . When the function of the unfixed action side fixing member  60  corresponds to the supporting function in operation  651 , the controller  70  may sense whether the function of the unfixed action side fixing member  60  is changed to the moving function, in operation  652 . When the function of the unfixed action side fixing member  60  is changed to the moving function in operation  652 , the controller  70  may reduce the power transmitted to the unfixed action side fixing member  60 , in operation  653 . 
     When the function of the unfixed action side fixing member  60  is not changed to the moving function in operation  652 , the controller  70  may determine whether both feet of the user are in contact with the ground, in operation  654 . When both feet of the user are in contact with the ground in operation  654 , the controller  70  may reduce the power transmitted to the unfixed action side fixing member  60 , in operation  653 . When both feet of the user are sensed as being not in contact with the ground in operation  654 , operation  652  may be performed. 
     While  FIG. 15  illustrates that operation  654  is performed after operation  651 , in some example embodiments, operation  654  may also be performed prior to operation  651  such that, when both feet of the user are in contact with the ground, the controller  70  may reduce the power in operation  653  immediately without sensing the function of the unfixed action side fixing member  60 . 
       FIG. 16  is a flowchart illustrating a method of controlling the motion assistance apparatus  10 , performed based on a direction of a load applied to an unfixed fixing member, according to some example embodiments. 
     Referring to  FIG. 16 ,  FIG. 16  illustrates performing motion assistance as illustrated in operation  620  of  FIGS. 10-12  according to some example embodiments in which the motion assistance is based on a direction of a load applied to an unfixed fixing member. 
     In some example embodiments, the motion assistance of operation  620  may include operation  660  of sensing a fixing state of the action side fixing member  60 , operation  661  of sensing a direction of a load applied to the unfixed action side fixing member  60 , and operation  622  of reducing power to be transmitted to the action side fixing member  60 . 
     In detail, in operation  660 , the sensing portion  100  may sense a fixing state of the action side fixing member  60 . 
     When the action side fixing member  60  is sensed as being unfixed in operation  660 , the controller  70  may detect a direction of a load applied to the unfixed action side fixing member  60 , in operation  661 . In some example embodiments, the controller  70  may detect that the direction of the load applied by the motion assistance apparatus  10  is a pushing direction, if the fixing member  50  is pushing the user&#39;s thighs backward. Likewise, in some example embodiments, the controller  70  may detect that the direction of the load applied by the motion assistance apparatus  10  is in a pulling direction, if the fixing member  50  is pulling the user&#39;s thighs forward. As discussed in more detail below, the controller  70  may detect that the direction of the load by detecting if the user&#39;s thigh is exerting pressure and/or force against a sensor. 
     The direction of the load applied to the unfixed action side fixing member  60  may be sensed using a pressure sensor disposed between the power transmitting member  50  and the action side fixing member  60 , or a tensile force sensor provided on the power transmitting member  50 . 
     When a value is sensed by the pressure sensor or the tensile force sensor, the controller  70  may verify that the load is applied to the unfixed action side fixing member  60  in a pushing direction. Conversely, when no value is sensed by the pressure sensor or the tensile force sensor, the controller  70  may verify that the load is applied to the unfixed action side fixing member  60  in a pulling direction. 
     When the direction of the load applied to the unfixed action side fixing member  60  corresponds to the pushing direction in operation  661 , the controller  70  may iteratively perform operation  661  until the load is applied in the pulling direction. 
     When the direction of the load applied to the unfixed action side fixing member  60  corresponds to the pulling direction in operation  661 , the controller  70  may reduce the power transmitted to the unfixed action side fixing member  60 , in operation  662 . 
     In the foregoing controlling method, by reducing the power transmitted to an action side fixing member  60  substantially incapable of providing a motion assistance force, the controller  70  may reduce the power consumption and increase a user safety. In addition, by continuously transmitting power to an action side fixing member  60  capable of providing a motion assistance force even in an unfixed state, a usage efficiency of the motion assistance apparatus  10  may increase. 
       FIG. 17  is a flowchart illustrating an operation of reducing power to be transmitted to the action side fixing member  60  in a method of controlling the motion assistance apparatus  10  according to some example embodiments. Referring to  FIG. 17 ,  FIG. 17  illustrates reducing power transmitted to the action side fixing member  60  as illustrated in operations  631 ,  633 ,  643 ,  653 , or  662  of  FIGS. 13-16  according to some example embodiments. Hereinafter, reducing power as illustrated in operation  631  will be described. However, the following descriptions may also apply to operations  633 ,  643 ,  653 , or  662 . 
     In some example embodiments, the power reduction of operation  631  may include operation  700  of reducing an output of the driving source  30 , and operation  710  of comparing the output of the driving source  30  to a predetermined output. 
     In detail, in operation  700 , the controller  70  may reduce an output of the driving source  30 . In operation  710 , the controller  70  may determine whether the reduced output of the driving source  30  is less than or equal to the desired (or, alternatively, the predetermined) output. 
     When the output of the driving source  30  excesses the desired (or, alternatively, the predetermined) output in operation  710 , the controller  70  may iteratively perform operation  700  until the output of the driving source  30  is less than or equal to the desired output. When the output of the driving source  30  is less than or equal to the desired (or, alternatively, the predetermined) output in operation  710 , the controller  70  may instruct the driving source  30  to continuously transmit power at the corresponding output. 
     In the foregoing control method, power may be continuously transmitted within a range safe although the main fixing member  20  or the action side fixing member  60  is unfixed. Thus, a usage efficiency of the motion assistance apparatus  10  may increase. 
     Operations  700  and  710  are provided as only an example of operation  631 ,  633 ,  643 ,  653 , or  662 . Example embodiments are not limited thereto. In some example embodiments, power to be transmitted to the action side fixing member  60  may be reduced by powering off the motion assistance apparatus  10 , by blocking power supplied to the driving source  30 , or by holding an operation to maintain a desired (or, alternatively, a predetermined) state of the driving source  30 . 
       FIG. 18  illustrates a controller according to some example embodiments. 
     Referring to  FIG. 18 , the controller  70  may include memory  1810  and a processor  1820  that may send data to and/or receive data from one another using a data bus  1830 . 
     The memory  1810  may be any device capable of storing data. For example, the memory may be a non-volatile memory, a volatile memory, a hard disk, an optical disk, and a combination of two or more of the above-mentioned devices. The memory may be a non-transitory computer readable medium. The non-transitory computer-readable media may also be a distributed network, so that the program instructions are stored and executed in a distributed fashion. The non-volatile memory may be a Read Only Memory (ROM), a Programmable Read Only Memory (PROM), an Erasable Programmable Read Only Memory (EPROM), or a flash memory. The volatile memory may be a Random Access Memory (RAM). 
     The processor  1820  may be any device capable of processing data including, for example, a microprocessor configured to carry out specific operations by performing arithmetical, logical, and input/output operations based on input data, or capable of executing instructions included in computer readable code. The processor  1820  may be a logic chip, for example, a central processing unit (CPU), a controller, or an application-specific integrated circuit (ASIC), that when, executing the instructions stored in the memory  1810 , configures the processor  1820  as a special purpose machine such that the processor  1820  is configured to determine if one or more of a waist fixing member  20 , and leg fixing members  60  are secured to the body of a user  1  using information received from sensor portions  80  and  100  to  500 . The processor  1820  may perform motion control  620  when the fixing members  20  and  60  are secured to the body of the user  1  and, thereafter, if one or more of the fixing members  20  and  60  are unfixed, the controller  70  may reduce the power transmitted to the unfixed fixing member  20  and  60  based on various factors. 
     The processor  1820  may reduce the power transmitted to the unfixed fixing member  20  and  60 , for example, when the user  1  is walking on a gradient with both feet on the ground, when the user  1  is one of moving with an unfixed fixing member  20  and  60  and standing still with both feet on the ground, or when a pulling force is applied to the fixing member  60 . Therefore, in some example embodiments, the motion assistance apparatus  10  may prevent sudden frontward bounce of the leg of the user  1  by continuing to provide motion assistance to the user while the user is walking downhill and the front of the fixing member  60  is unfixed. Further, in other example embodiments, the motion assistance apparatus  10  may reduce unnecessary power usage by reducing the force applied to the user  1  when the fixing member  60  is unfixed. Further still, in other example embodiments, the motion assistance apparatus  10  may continue to provide motion assistance to the user  1  when the fixing member  60  is unfixed, if the direction of the assistance is a pushing direction so as to extend the amount of time motion assistance is provided to the user. 
     A number of example embodiments have been described above. Nevertheless, it should be understood that various modifications may be made. For example, suitable results may be achieved if the described techniques are performed in a different order and/or if components in a described system, architecture, device, or circuit are combined in a different manner and/or replaced or supplemented by other components or their equivalents. Accordingly, other implementations are within the scope of the following claims.