Patent Publication Number: US-2015066325-A1

Title: Mobile object

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to a mobile object such as a manually propelled vehicle. 
     RELATED ART 
     In recent years, the installing of power-assist functions into manually propelled vehicles (one form of a mobile object, for example, an ambulatory assist vehicle to support elderly people with a weak physique or people with trouble walking, to go out) has been studied. This type of manually propelled vehicle is generally configured to drive forward by being gripped by a user. 
     With a manually propelled vehicle comprising a power-assist function, human power can be assisted when used by a user. Therefore, for example, operations that require a large force, such as carrying a heavy load, can be carried out relatively easily. 
     PATENT LITERATURE 
     [Patent Literature 1] Japanese Unexamined Patent Application Publication No. 2013-123940 
     However, with the manually propelled vehicle described above, while an operation that requires a large force is made easier by the power-assist function, stopping the vehicle with only a wire braking operation or the like may become difficult. 
     Therefore, there is a need to devise a good way so that even a weak user can perform an easy braking operation (including an operation to reduce vehicle speed in addition to stopping the vehicle). In conventional art, the form of the braking operation does not consider actual circumstances of the mode of use of the manually propelled vehicle. 
     For example, the braking operation may be performed urgently to ensure safety or the like. Therefore, the braking operation is not performed intuitively and quickly enough for the user. Further, the user may release a hand accidentally while the manually propelled vehicle is being driven. If the vehicle is designed to reduce the speed by considering such events as a braking operation, safety can be sufficiently ensured. 
     SUMMARY OF THE INVENTION 
     One or more embodiments of the present invention provide a mobile object that can realize a braking operation in an appropriate form while having a power-assist function. 
     A mobile object according to one or more embodiments may comprise a vehicle body; a grip attached to the vehicle body; a detector that detects a value of pressure applied to the grip by a user of the mobile object; a wheel for moving the vehicle body; a wheel driver that drives the wheel; and a controller that controls the wheel driver as the user walks while holding onto the grip and that performs braking to decelerate a rotation speed of the wheel when the detected value of the detector satisfies a predetermined condition. 
     The mobile object according to one or more embodiments enables a braking operation in an appropriate form while having a power-assist function. Further, according to one or more embodiments, the detector may be a pressure sensor provided on the grip. 
     According to one or more embodiments, the predetermined condition may be satisfied when the detected value exceeds a first predetermined threshold. According to one or more embodiments, the predetermined condition may be satisfied when the detected value is lower than a second predetermined threshold. 
     The mobile object according to one or more embodiments may further comprise a threshold setting unit that sets the first predetermined threshold, stores a history of detected values that exceed the first predetermined threshold, and updates the first predetermined threshold based on the history of the detected values. Further, according to one or more embodiments, the threshold setting unit may set the first predetermined threshold to be a mean value of all the detected values stored in the history. Furthermore, the mobile object according to one or more embodiments may further comprise a mode setting unit that sets any of a plurality of user modes, wherein the threshold setting unit may set the first predetermined threshold for each of the user modes. 
     Moreover, the mobile object according to one or more embodiments may further comprise a mode setting unit that sets any of a plurality of user modes based on an output of the detector that exceeds the first predetermined threshold and on predetermined reference information for each of the plurality of user modes. 
     According to one or more embodiments, the controller may determine a pattern of a driving force for each of the plurality of user modes, and the wheel driver may drive the wheel based on the pattern associated with each of the plurality of user modes. 
     A mobile object according to one or more embodiments may comprise: a vehicle body; a grip attached to the vehicle body; a wheel for moving the mobile object; a wheel driver that drives the wheel; a brake lever operated by the user when applying a wire brake; and a controller that controls the wheel driver as the user walks while holding onto the grip and that performs braking to control to decelerate a rotation speed of the wheel when a detected value of the brake lever exceeds a default value. 
     According to one or more embodiments, the braking may be an operation to set a target rotation speed of a motor driving the wheel to zero. 
     According to one or more embodiments, a control method for controlling a mobile object comprising a vehicle body, a grip attached to the vehicle body to be gripped by a user walking with the mobile object, and a wheel for moving the mobile object may comprise: driving the wheel as the user walks while holding onto the grip; detecting a value of pressure applied to the grip; and controlling the driving to decelerate a rotation speed of the wheel when the detected value satisfies a predetermined condition. 
     The mobile object according to one or more embodiments of the present invention enables a braking operation in an appropriate form while having a power-assist function. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external view of a mobile object according to one or more embodiments when viewed from behind; 
         FIG. 2  is an external view of the mobile object according to one or more embodiments when viewed from the left side; 
         FIG. 3  is an external view of a vicinity of the handle of the mobile object according to one or more embodiments when viewed from behind; 
         FIG. 4  is a perspective view of the vicinity of the handle of the mobile object according to one or more embodiments; 
         FIG. 5  is a functional block diagram of the mobile object according to one or more embodiments of a first example; 
         FIG. 6  is a schematic plan view illustrating an example of one configuration of a wheel and a wheel driver; 
         FIG. 7  is a functional block diagram illustrating an example of one configuration of the wheel drive functional part; 
         FIG. 8  is a plan view of the handle according to one or more embodiments; 
         FIG. 9  is an explanatory diagram that relates to a brake lever according to one or more embodiments; 
         FIG. 10  is an explanatory diagram that relates to a mode of use of the mobile object according to one or more embodiments; 
         FIG. 11  is a flowchart of a process that relates to the braking or brake control operation of one or more embodiments of the first example; 
         FIG. 12  is a flowchart of a process that relates to the braking or brake control operation of one or more embodiments of a second example; 
         FIG. 13  is a functional block diagram of a mobile object according to one or more embodiments of a third example; 
         FIG. 14  is a flowchart of a process that relates to the braking or brake control operation of one or more embodiments of the third example; 
         FIG. 15  is a functional block diagram of a mobile object according to one or more embodiments of a fourth example; 
         FIG. 16  is an explanatory diagram that relates a memory according to one or more embodiments of the fourth example; 
         FIG. 17  is a flowchart of a process that relates to the braking or brake control operation of one or more embodiments of the fourth example; 
         FIG. 18  is a functional block diagram of a mobile object according to one or more embodiments of a fifth example; 
         FIG. 19  is an explanatory diagram that relates a memory according to one or more embodiments of the fifth example; and 
         FIG. 20  is a flowchart of a process that relates to the braking or brake control operation of one or more embodiments of the fifth example. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     Embodiments of the present invention will be described hereinafter with reference to an example each of the first to fifth examples. 
     1. FIRST EXAMPLE 
     [Configuration and the like of Mobile Object] 
     First, one or more embodiments of a first example will be described.  FIG. 1  is an external view of a mobile object  1  (e.g., manually propelled vehicle such as an ambulatory assist vehicle) when viewed from behind, and  FIG. 2  is an external view of the mobile object  1  when viewed from the left side. The directions of forward, backward, left, and right in the descriptions thereafter are the directions illustrated in  FIG. 1  and  FIG. 2  unless otherwise specified. 
       FIG. 3  is an external view of a vicinity of the handle of the mobile object  1  when viewed from behind. Further,  FIG. 4  is a perspective view of the vicinity of the handle of the mobile object  1 . Furthermore,  FIG. 5  is a functional block diagram of the mobile object  1 . A configuration and the like of the mobile object  1  are described with appropriate reference to each drawing described above. 
     The mobile object  1  may be a manually propelled vehicle (a so-called walker) to assist walking of a user (mainly elderly with a weak lower body) and may be used as a basket for carrying baggage and a seat for resting. The mobile object  1  may comprise a vehicle body  10 , a handle  20 , a wheel  30 , a baggage compartment  40 , a backrest  50 , a user interface  60 , a sensor  70 , a controller  80 , an electromotor  90 , and a power supply  100 . 
     The vehicle body  10  may be a chassis of the mobile object  1  (framework) on which each of the configuration elements  20  to  100  listed above may be mounted. Stainless steel, aluminum alloy, or the like may be used for the frame material forming the vehicle body  10 . 
     The handle  20  may be a member where the user grips at the time of walking and is connected to a strut member  11  of the vehicle body  10 . The user can drive the mobile object  1  by applying human power through gripping both ends of the handlebar  21  with both hands. 
     The wheel  30  may be an annular member in order to move the vehicle body  10  along the ground by rotating in harmony with the walking of the user.  FIG. 6  is a schematic plan view illustrating an example of one configuration of the wheel  30  and a wheel driver  91 . As illustrated in  FIG. 6 , the wheel  30  may be a four-wheel structure comprising drive wheels  31  (left and right drive wheels  31 L and  31 R) that are rotated at the axle center by human power (or auxiliary power) and idler wheels  32  (left and right idler wheels  32 L and  32 R) for turning direction. The left and right drive wheels ( 31 L and  31 R) may be driven and controlled independently on the rotation speed and rotation direction respectively by the wheel driver ( 91 L and  91 R) corresponding to each. 
     The baggage compartment  40  may be a box-shape member that can store personal belongings inside. A cushion member may be attached on the upper lid of the baggage compartment  40 , and may function as a seating surface for the user to sit on. 
     The backrest  50  may be a plate-like member for the user to lean back against when seated. In one or more embodiments of the present example, the vehicle body  10  and the strut member  11  are designed to be relatively wide and be diverted as the backrest  50 . 
     The user interface  60  may be means for exchanging information between the user and the controller  80 , and may comprise, for example, a manual operation  61  (such as an ON/OFF switch button of the electromotor assistance function) and a notification  62  (such as a speaker, light-emitting diode, liquid crystal display panel). The user interface  60  may be provided at a position where the user can easily operate (for example, the handle  20  may be near the height of the eyes of the user). 
     The sensor  70  may be used to monitor surrounding conditions, usage condition of the mobile object  1 , a walking posture of the user, or the strength of the grip force. In one or more embodiments of the present example, the sensor  70  may comprise a handle sensor  71  that detects a displacement state of the handlebar  21  and a pressure sensor  72  (pressure sensor is used to collectively describe a left side pressure sensor  72 L and a right side pressure sensor  72 R, each of which will be described in greater details below) that detects the gripping strength of the user (grip strength). The pressure sensor  72  may be, for example, a capacitance type pressure sensor, or a load cell, strain gauge, piezo element, one used a pressure-sensitive conductive rubber, or one formed by a combination thereof. 
     The controller  80  may be a logic circuit (such as a microcomputer) that comprehensively controls the user interface  60 , sensor  70 , and electromotor  90 . The controller  80  may comprise a processor  81  and a wheel drive controller  82  as functional blocks to realize power assistance according to an intent of the user by setting various parameters (rotation direction of the motor, rotation speed, and each target value of the rotation torque) of the wheel driver  91  according to the output of the handle sensor  71 . 
     The processor  81  may determine a driving target value of the left and right drive wheels ( 31 L and  31 R) according to an output of each sensor provided in the sensor  70 . The wheel drive controller  82  may control the rotation direction and the rotation speed of the left and right drive wheels ( 31 L and  31 R) respectively and individually according to the driving target values described above. 
     The electromotor  90  may be means to drive each component of the mobile object  1  by electromotor according to an instruction from the controller  80  and comprising the wheel driver  91 . The wheel driver  91  may electrically drive the left and right drive wheels ( 31 L and  31 R) that are a part of the wheel  30  according to an instruction from the controller  80 . As illustrated in  FIG. 6 , the left and the right wheel drivers ( 91 L and  91 R) may be provided individually in order to control the left and the right drive wheels ( 31 L and  31 R) independently. 
     The power supply  100  may be means for supplying the electric power to the user interface  60 , sensor  70 , controller  80 , and the electromotor  90 . A secondary battery (such as a nickel-hydrogen battery or lithium-ion battery) attaching to the vehicle body  10  in a removable manner may be used as the power supply  100 . 
       FIG. 7  is a functional block diagram illustrating an example of one configuration of the wheel driver ( 91 L and  91 R). The wheel driver  91 L may comprise a motor  911 L, a motor driver  912 L, a current sensor  913 L, and a rotation angle sensor  914 L. Further, the wheel driver  91 R may comprise a motor  911 R, a motor driver  912 R, a current sensor  913 R, and a rotation angle sensor  914 R. 
     The motor  911 L may rotate and drive the left drive wheel  31 L independently. The motor driver  912 L may be an inverter circuit for generating a drive current for the motor  911 L according to a control signal from the controller  80 . The current sensor  913 L may detect a drive current supply to the motor  911 L. The rotation angle sensor  914 L may detect the rotation angle of the motor  911 L. 
     The motor  911 R may rotate and drive the right drive wheel  31 R independently. The motor driver  912 R may be an inverter circuit for generating a drive current for the motor  911 R according to a control signal from the controller  80 . The current sensor  913 R may detect a drive current supply to the motor  911 R. The rotation angle sensor  914 R may detect the rotation angle of the motor  911 R. 
     The wheel drive controller  82  may perform feedback control of each of the motor drivers ( 912 L and  912 R) to match the rotation direction and rotation speed of the motors  911 L and  911 R with the target values according to outputs of each of the current sensors ( 913 L and  913 R) and each of the rotation angle sensors ( 914 L and  914 R). 
       FIG. 8  is a plan view of a handle  20  (when the exterior member is removed). The handle  20  may comprise a handlebar  21 , a middle handle  22 , and a handle holder  23 , a neutral holding section  24 , and a brake lever  25 . 
       FIG. 8  is a plan view of the handle  20  when viewed from above; however, an engaging portion (mating portion of a guide pin  233 ) between the handlebar  21  and the handle holder  23  is illustrated in a horizontally cross-sectional view for purposes of better illustrating the structure. 
     The handlebar  21  may be a rod-like member for the user to grip with both hands, and provided to extend in a lateral direction. Near the two ends of the lateral direction (lengthwise direction), a left grip  26 L and a right grip  26 R (hereinafter, these may be referred to as “grip  26 ” collectively) may be provided so that the user can grip the handlebar  21  with both hands easily. 
     The left grip  26 L may be a portion where the user grips with left hand, and may comprise the left side pressure sensor  72 L. The left side pressure sensor  72 L may be suitably disposed so that the gripping force of the left grip  26 L by the user can be detected accurately. The left side pressure sensor  72 L may be, for example, a thin sheet-like form wrapped around the left grip  26 L. 
     The right grip  26 R may be a portion where the user grips with right hand, and may comprise the right side pressure sensor  72 R. The right side pressure sensor  72 R may be suitably disposed so that the gripping force of the right grip  26 R by the user can be detected accurately. The right side pressure sensor  72 R may be, for example, a thin sheet-like form wrapped around the right grip  26 R. 
     Further, a handle sensor  71  that detects a displacement state of the handlebar  21  may be mounted on a surface of the handlebar  21 . A first sensor  711 , a second sensor  712 , a third sensor  713 , and a fourth sensor  714  may be provided as the handle sensor  71 . 
     The first sensor  711  may be provided on a front side of a first region nearer to a right end than a middle of the lengthwise handlebar  21 , and detect that the first region of the handlebar  21  is displaced in a forward direction from a predetermined neutral position by detecting contact with a first contact surface  231  (surface facing the front of the handlebar  21 ) of a handle holder  23 . 
     The second sensor  712  may be provided on a back side of a second region nearer to a left end than the middle of the lengthwise handlebar  21 , and detect that the second region of the handlebar  21 is displaced in a rearward direction from the predetermined neutral position by detecting contact with a second contact surface  232  (surface facing the back of the handlebar  21 ) of the handle holder  23 . 
     The third sensor  713  may be provided at the back side of the first region (opposite to the first sensor  711 ) of the handlebar  21 , and detect that the first region of the handlebar  21 is displaced in the rearward direction from the neutral position by detecting contact with the second contact surface  232 . 
     The fourth sensor  714  may be provided at the front side of the second region (opposite to the second sensor  712 ) of the handlebar  21 , and may detect that the second region of the handlebar  2 l is displaced in the forward direction from the neutral position by detecting a contact with the first contact surface  231 . 
     The first to fourth sensors ( 711  to  714 ) are all pressure-sensitive electrically conductive elements that convert a change in pressure to a change in electrical resistance. However, the first to fourth sensors  711  to  714  are not limited to the pressure-sensitive electrically conductive elements, and may be, for example, a mechanical switch, an optical sensor, or other known apparatuses that detect proximity/deviation between the handlebar  21  and the handle holder  23 . 
     The middle handle  22  may be a U-shaped member for the user to grip with one hand. The middle handle  22  may be rigidly coupled between two points of the middle portion in the lengthwise direction of the handlebar  21 , so that the operation force applied to the middle handle  21  is transferred to the handle bar  21 . Accordingly, the user can use the mobile object  1  by operating the middle handle  22  with one hand even when the user cannot operate the handle bar  21  using both hands (such as when holding an umbrella in one hand). The installation of the middle handle  22  may be omitted. 
     The handle holder  23  may be fixed to the strut member  11  of the vehicle body  10 , and support the handlebar  21  while allowing a displacement of the handlebar  21  within a predetermined range. The handle holder  23  may comprise two guide pins  233  (diameter: r) where both ends are held by the first contact surface  231  and the second contact surface  232 . The guide pin  233  may be fitted to a guide pin fitting hole of the handlebar  21 . Accordingly, the displacement of the handlebar  21  is fundamentally restricted to the axial direction (front and back direction). 
     The diameter R of the guide pin fitting hole drilled into the handlebar  21  may be designed to be slightly larger than the diameter r of the guide pin  233 . That is, an intentional fitting play may be provided to the handle holder  23 . Therefore, the handlebar  21  is not only displaced in the forward and the rearward directions, but also displaced in the left and the right turning directions within the predetermined range (within the play range by the fitting play) by receiving the operation force by the user. 
     The neutral holding section  24  may be a member for biasing back the handlebar  21  to the neutral position. According to one or more embodiments of the present example, an elastic member may be provided between the handlebar  21  and the handle holder  23  as the neutral holding section  24 . For the elastic member, sponge, rubber in which a variety of hardness is selectable, or a metal, resin, or other materials having resilient properties such as a leaf spring may be suitably used. Further, when each sensor ( 711  to  714 ) is made of an elastic member, an elastic member may not be provided in each local contact location. 
     A brake lever  25  may be a lever operated by the user when applying a friction brake by using a wire brake. The brake lever  25  may be provided near the grips  26  of both the left and the right sides, respectively, (where the user can grip the grip  26  and the brake lever  25  together) as illustrated in  FIG. 9  (cross-sectional view near the brake lever  25 ). The brake lever  25  may be supported in a pivotal manner around a pivotal axis  25   a  and may be connected to a brake shoe, not illustrated, via a brake wire  25   b.    
     When the user operates the brake lever  25  (for example, grasping both the grip  26  and the brake lever  25  firmly), the brake lever  25  may be rotated in the direction closer to the grip  26 . Accordingly, the brake wire  25   b  may be pulled towards the brake lever  25   b  and the brake shoe may be pressed against the wheel  30 . 
     The more force the user operates the brake lever  25  with, the greater the operation amount (rotation amount) of the brake lever  25  increases and a larger friction is generated between the brake shoe and the wheel  30 . Therefore, when the user operates the brake lever  25  with a sufficient force, the friction brake can be applied to the mobile object  1 . 
     However, there may be concern that operating the brake lever  25  with sufficient force may be difficult and that the wire brake may not be properly applied by a weak user. Accordingly, one or more embodiments of the present example may be configured so that even a weak user can apply the brake easily. Detailed description pertaining to making the braking mechanism easier to apply is provided below. The installation of the wire brake (including brake lever  25 ) may be omitted with the exception of one or more embodiments of a third example described later. 
     [Power-Assist Function] 
     A mobile object  1  according to one or more embodiments is illustrated in  FIG. 10 . For example, the user may walk while propelling or moving the vehicle body  10  by gripping the grip  26  with both hands. At that time, the controller  80  controls the electromotive drive of the drive wheel  31  to give power assistance (e.g., electromotor assistance). 
     When the mobile object  1  is moving forward, the contact of a first contact surface  231  with both the first sensor  711  and the fourth sensor  714  may be detected by the handlebar  21  as the handlebar  21  is pushed in the forward direction by the user. At that time, the controller  80  may set various parameters of the wheel driver  91 L and  91 R to give identical forward torque to the drive forces DL and DR in the drive wheels  31 L and  31 R. With this type of power assistance, the user can move the mobile object  1  forward smoothly and safely. 
     When the mobile object  1  is moving rearward, contact with a second contact surface  232  is detected by both the second sensor  712  and the third sensor  713  as the handlebar  21  is pulled in the rearward direction by the user. At that time, the controller  80  may set various parameters of the wheel driver  91 L and  91 R to give identical rearward torque to the drive forces DL and DR in the drive wheels  31 L and  31 R. With this type of power assistance, the user can move the mobile object  1  rearward smoothly and safely. 
     When the mobile object  1  is turning right, the contact with the second contact surface  232  may be detected by the third sensor  713  and the contact with the first contact surface  231  may be detected by the fourth sensor  714  as the handlebar  21  is twisted in the right turning direction by the user. At that time, the controller  80  may set various parameters of the wheel driver  91 L and  91 R to give different forward torques (DL&lt;DR) as the drive forces DL and DR of the drive wheels  31 L and  31 R. With these power assistances, the user can turn the mobile object  1  to the right smoothly and safely. 
     When the mobile object  1  is turning left, contact with the first contact surface  231  may be detected by the first sensor  711  and contact with the second contact surface  232  may be detected by the second sensor  712  as the handlebar  21  is twisted in the left turning direction by the user. At that time, the controller  80  may set various parameters of the wheel driver  91 L and  91 R to give different forward torques (DL&gt;DR) as the drive forces DL and DR of the drive wheels  31 L and  31 R. With this type of power assistance, the user can turn the mobile object  1  to the right smoothly and safely. 
     [Brake Control Operation or Braking] 
     Further, the controller  80  may execute a brake control operation or braking when the detected result of the pressure sensor  72  satisfies a predetermined condition, e.g., when a value detected by the pressure sensor  72  exceeds or falls below a certain value. A description of a series of processes relating to the brake control operation is given below with reference to a flowchart illustrated in  FIG. 11 . 
     The controller  80  may monitor whether the mobile object  1  is in a propelling state (forward, backward, turning right or turning left) (step S 11 ). When the mobile object  1  is in the propelling state (Y in step S 11 ), the controller  80  may read the current detected value of the pressure sensor  72  (step S 12 ). 
     Then, the controller  80  may determine whether the detected value of the pressure sensor  72  exceeds the predetermined threshold al (step S 13 ). The threshold al may be set in advance or predetermined as a value corresponding to the situation where a relatively weak user grips the grip  26  with some strength. That is, the threshold al may be set appropriately so that weak users can easily apply the braking operation. 
     According to the result of the determination, when the detected value does not exceed the threshold α 1  (N in step S 13 ), the controller  80  may repeat the operation of step S 11 . On the other hand, when the detected value exceeds the threshold α 1  (Y in step S 13 ), the controller  80  may determine that the braking operation is activated (step S 14 ) and execute the brake control operation (step S 15 ). In one or more embodiments of the present example, the operation in which the detected value of the pressure sensor  72  may be caused to exceed the threshold α 1  by a stronger gripping force on the grip  26  corresponds to a braking operation. 
     Further, the brake control operation may control the electromotive drive of the drive wheel  31  to reduce the rotation speed, and may be, for example, an operation that sets the target rotation speed of the motor  911 , which drives the drive wheel  31 , to zero. However, the specific form of the brake control operation is not limited thereto, but a variety of operations that can control the mobile object  1  may also be applicable to the brake control operation. 
     By performing the brake control operation, the rotation of the motor  911  may decelerate gradually. When the rotation speed of the motor  911  (or the drive wheel  31 ) becomes zero or a sufficiently small value, the purpose of the brake control operation at that time is achieved. Thereafter, the controller  80  may repeat the operation of step S 11 . 
     The brake control operation may be performed when at least the left or the right detected value of the pressure sensor  72  exceeds the threshold α 1 , or when only detected values of the pressure sensors  72  of both the left and the right exceed the threshold α 1 . 
     Further, the break control operation may apply the brake on the left drive wheel  31 L and the right drive wheel  31 R simultaneously, or may apply the brake on these drive wheels individually. Furthermore, when applying the brake individually, the left drive wheel  31 L may be braked when the detected value of the left side pressure sensor  72 L exceeds the threshold al, and the right drive wheel  31 R may be braked when the detected value of the right side pressure sensor  72 R exceeds the threshold α 1 . 
     By performing the series of operations described above (step S 11 ˜S 15 ), the braking operation can be carried out even by a weak user. Further, this braking operation may be operated by simply gripping the grip  26  with slight force, and is made so that the user can perform the operation instantly and intuitively. Therefore, the user can easily apply the braking operation even in urgent situations. 
     2. SECOND EXAMPLE 
     Next, one or more embodiments of the second example will be described. In the following, a description will be given focusing on parts that are different from one or more embodiments of the first example, and the description of parts that are common is omitted. 
     A series of processes of the brake control operation according to one or more embodiments of the second example will be described with reference to a flowchart shown in  FIG. 12 . 
     A controller  80  may monitor whether the mobile object  1  is in a propelling state (step S 21 ). When the mobile object  1  is in a propelling state (Y in step S 21 ), the controller  80  may read a detected value of the current pressure sensor  72  (step S 22 ). 
     Then, the controller  80  may determine whether the detected value of the pressure sensor  72  is lower than a predetermined threshold α 2  (step S 23 ). The threshold α 2  may be set in advance as a value corresponding to a condition where the user releases the hand from the grip  26 . That is, the threshold α 2  may be set suitably so that the braking operation is activated when the user releases the hand from grip  26 . 
     From a result of the determination, when the detected value is not lower than the threshold α 2  (N in step S 23 ), the controller  80  may repeat the operation of step S 21 . On the other hand, when the detected value is lower than the threshold α 2  (Y in step S 23 ), the controller may determine that the braking operation is activated (step S 24 ) and execute the brake control operation (step S 25 ). That is, in one or more embodiments of the present example, the operation in which the detected value of the pressure sensor  72  is lower than the threshold α 2  by releasing the hand from the grip  26  corresponds to the braking operation. 
     By performing the brake control operation, a motor  911  may reduce the rotation gradually. When the rotation speed of the motor  911  (or the drive wheel  31 ) is zero or a sufficiently small value, the purpose of the brake control operation is achieved. Subsequently, the controller  80  repeats the operation of step S 21 . 
     By performing the series of operations described above (steps S 21  to S 25 ), the braking operation can be easily carried out even by a weak user. Further, this braking operation may be activated even when the user releases the hand accidentally from the grip  26 . Therefore, the braking operation may also prevent a situation where the mobile object  1  is driven against the will of the user. 
     3. THIRD EXAMPLE 
     Next, one or more embodiments of the third example will be described. In the following, a description will be given focusing on parts that are different from one or more embodiments of the first example, and the description of parts that are common is omitted. 
       FIG. 13  is a functional block diagram of the mobile object  1  according to one or more embodiments of the third example. As illustrated in this diagram, a brake lever operation amount detector  73  may be provided instead of the pressure sensor  72  in the mobile object  1  of one or more embodiments of the third example. 
     The brake lever operation amount detector  73  may be means to detect the operation amount (rotation amount) of the brake lever  25 . The brake lever operation amount detector  73  can be realized by using, for example, a wire displacement sensor, potentiometer, rotary encoder, Hall IC, or strain gauge. 
     In addition, when the wire displacement sensor is used, the wire displacement sensor may be attached to the brake wire  25   b  (see  FIG. 9 ), and the displacement of the brake wire  25   b  may be converted to a resistance value. Further, when the potentiometer is used, the potentiometer may be attached to the pivotal axis  25   a  of the brake lever, and the rotation angle of the brake lever  25  may be converted to a resistance value. Use of such principles allows the operation amount of the brake lever  25  to be detected. 
     A series of processes of a brake control operation according to one or more embodiments of the third example will be described with reference to a flowchart shown in  FIG. 14 . 
     The controller  80  may monitor whether the mobile object  1  is in a propelling state (step S 31 ). When the mobile object  1  is in the propelling state (Y in step S 31 ), the controller  80  may detect an operation amount of the current brake lever  25  (step S 32 ). 
     Then, the controller  80  may determine whether the operation value of the brake lever  25  exceeds a predetermined threshold α 3  (step S 33 ). The threshold α 3  may be set in advance as a value corresponding to a condition where a relatively weak user operates the brake lever  25  with some strength. In other words, the threshold α 3  may be set suitably so that even a weak user can easily carry out the braking operation. 
     From a result of the determination, when the operation amount does not exceed the threshold α 3  (N in step S 33 ), the controller  80  may repeat the operation of step S 31 . On the other hand, when the detected value exceeds the threshold α 3  (Y in step S 33 ), the controller may determine that the braking operation is activated (step S 34 ) and execute the brake control operation (step S 35 ). That is, in one or more embodiments of the present example, the operation in which the operation amount of the brake lever  25  is caused to exceed the threshold α 3  by rotating the brake lever  25  to some extent corresponds to the braking operation. 
     By performing the brake control operation, a motor  911  may reduce the rotation gradually. When the rotation speed of the motor  911  (or the drive wheel  31 ) is zero or a sufficiently small value, the purpose of the brake control operation at that time is achieved. Subsequently, the controller  80  may repeat the operation of step S 31 . 
     By performing the series of operations described above (steps S 31  to S 35 ), the braking operation can be easily carried out even by a weak user. Further, this braking operation may be activated when the user tries to apply the wire brake, and the power assistance may be stopped as a result. Therefore, one or more embodiments of the mobile object  1  can prevent a situation where an opposing force is generated simultaneously such as applying the wire brake when the power assistance is performed. 
     4. FOURTH EXAMPLE 
     Next, one or more embodiments of a fourth example will be described. In the following, a description will be given focusing on parts that are different from one or more embodiments of the first example, and the description of parts that are common is omitted. 
       FIG. 15  is a functional block diagram of the mobile object  1  according to one or more embodiments of the fourth example. As illustrated in this diagram, a memory  75  may be provided in the mobile object  1  of one or more embodiments of the fourth example. The memory  75  may be configured by using, for example, non-volatile memory (such as flash memory) that is rewritable, and a variety of information is stored according to instructions by the controller  80 . 
       FIG. 16  schematically illustrates the information stored in the memory  75 . As illustrated in the figure, the “threshold α 1 ” and “history of the pressure value” are stored in the memory  75  for each of a plurality of user IDs that is registered in advance. In one or more embodiments of the present example, the plurality user IDs can be registered in this way in the initial setting or the like on the assumption that a plurality of users share the mobile object  1 . 
     Further, the initial value of the threshold α 1  stored in the memory  75  may be determined, for example, based on the detected value of the pressure sensor  72  when the user initiates a braking operation at the time of the initial setting or the like, or may be used as a default standard value. The threshold α 1  stored in the memory  75  may be updated with the history change of the pressure value as described later. The history of the pressure value stored in the memory  75 , as is apparent from a description given below, may be a history of the pressure values of the braking operations that have been performed in the past. 
     A series of processes of a brake control operation according to one or more embodiments of the fourth example will be described with reference to a flowchart shown in  FIG. 17 . 
     The controller  80  may receive an identification (any one of identifications from each user ID that are registered in advance) of the user ID by the user through, for example, a manual operation  61  (step S 41 ). At that time, a person who is going to use the mobile object  1  can now specify a user ID of his or her own. 
     When the identification of the user ID is made, the controller  80  may set a user mode corresponding to the user ID (step S 42 ). The user mode may be an operation mode used by a specific user, and the threshold α 1  may be set to correspond (stored in the memory  75 ) to the specific user in one or more embodiments of the present example. 
     Subsequently, the controller  80  may monitor whether the mobile object  1  is in a propelling state (step S 43 ). When the mobile object  1  is in a propelling state (Y in step S 43 ), the controller  80  may read a detected value of the current pressure sensor  72  (step S 44 ). 
     Then, the controller  80  may determine whether the detected value of the pressure sensor  72  exceeds the threshold α 1  (step S 45 ). As a result of the determination, when the detected value does not exceed the threshold α 1  (N in step S 45 ), the controller  80  may repeat the operation of the step S 43 . On the other hand, when the detected value exceeds the threshold α 1  (Y in step S 45 ), the controller  80  may determine that the braking operation is activated (step S 46 ) and execute the brake control operation (step S 47 ). 
     By performing the brake control operation, the rotation of the motor  911  may decelerate gradually. When the rotation speed of the motor  911  (or the drive wheel  31 ) becomes zero or a sufficiently small value, the purpose of the brake control operation at that time is achieved. 
     Furthermore, the controller  80  may add the pressure value (detected value of the pressure sensor  72  when exceeding the threshold α 1 ) to the history of the pressure value stored in the memory  75  (step S 48 ). Accordingly, the history of the pressure value is modified. 
     Then, the controller  80  may update the threshold α 1  based on the history of the latest pressure value so that if the pressure value tends to be lower, the threshold α 1  may be lowered accordingly, and if the pressure value tends to be higher, the threshold α 1  may be raised accordingly (step S 49 ). 
     For example, the controller  80  may calculate a mean value for every value contained in the history, and this mean value (or a value obtained by adding a predetermined correction to the mean value) may become a new threshold α 1 . Accordingly, the threshold α 1  stored in the memory  75  is updated, and the threshold α 1 , after being updated and newly set, will be reflected in the operation thereafter. Subsequently, the controller  80  may repeat the operation of step S 43 . 
     By performing the series of operations described above (steps S 41  to S 49 ), the braking operation can be easily carried out even by a weak user. Further, according to one or more embodiments of the present example, even if there are individual differences in the gripping strength of the users (differences such as sex, age, presence or absence of rheumatoid arthritis, or the like), the appropriate threshold al can be set for each user, and therefore, any user can comfortably use the mobile object  1 . 
     Furthermore, according to one or more embodiments of the present example, the threshold α 1  may be appropriately updated based on the history of the pressure value for each user. Therefore, even when a user&#39;s grip strength changes due to changes in the user&#39;s physical condition (e.g., aging) or when the mobile object  1  deteriorates through repeated use, the user can still use the mobile object  1  comfortably. 
     5. FIFTH EXAMPLE 
     Next, one or more embodiments of a fifth example will be described. In the following, a description will be given focusing on parts that are different from one or more embodiments of the first example, and the description of parts that are common is omitted. 
       FIG. 18  is a functional block diagram of the mobile object  1  according to one or more embodiments of the fifth example. As illustrated in this diagram, a memory  75  may be provided in the mobile object  1  of one or more embodiments of the fifth example. The memory  75  may be configured by using, for example, non-volatile memory (such as flash memory) that is rewritable, and a variety of information is stored according to instructions by the controller  80 . 
       FIG. 19  schematically illustrates the information stored in the memory  75 . As illustrated in the figure, information that relates to characteristics of the braking operation and a pattern of the electromotive drive force may be stored in the memory  75  for each of a plurality of user IDs that is registered in advance. In one or more embodiments of the present example, the plurality user IDs can be registered in this way at the initial setting on the assumption that a plurality of users share the mobile object  1 . 
     In one or more embodiments of the present example, “operation strength” and “operation time” may be stored as information relating to characteristics of the braking operation. The “operation strength” may refer to the strength of the braking operation (strength of the gripping force). For example, a value of the “operation strength” may be the maximum value of the pressure sensor  72  or the mean value of the outputs of the pressure sensor  72  when the user has initiated a braking operation at the time of the initial setting or the like. 
     Further, “operation time” may refer to a time of the braking operation (length of time the strong gripping continues). For example, “operation time” may be a time in which the output value of the pressure sensor  72  continually exceeds the threshold α 1  when the user has initiated a braking operation at the time of the initial setting or the like. Differences in the characteristics of the braking operation may exist among different users; therefore, the differences in “operation strength” and the “operation time” may be attributed to the specific user. 
     Further, “assisting force” and “braking force” may be stored in one or more embodiments of the present example as information relating to a pattern of the force of the electromotive drive. The assisting force may be a power assistance force when the mobile object is propelled. Further, the braking force may be the force of the brake when the brake control operation is performed by the braking operation. 
     The assisting force and the braking force may be set, for example, relatively weak for a user with a weak lower body, and relatively strong for a user with a strong lower body so that the mobile object  1  can be more safely and comfortably used. The assisting force and the braking force stored in the memory  75  are determined suitably, for example, by each user at the time of the initial setting so that each person can use the mobile object  1  comfortably. 
     Next, a series of processes of a brake control operation according to one or more embodiments of the fifth example will be described with reference to a flowchart shown in  FIG. 20 . 
     The controller  80  may receive an identification (any one of identifications from all user IDs that are registered in advance) of the user ID by the user through, for example, a manual operation  61  (step S 51 ). At that time, a person who is going to use the mobile object  1  can now identify or specify a user ID of his or her own. 
     When the identification of the user ID is made, the controller  80  may set a user mode corresponding to the user ID (step S 52 ). The user mode may be an operation mode on the assumption of use by a specific user, and the assisting force and braking force may be set to correspond (stored in the memory  75 ) to the user in one or more embodiments of the present example. 
     The processes from step S 51  to S 52  may be omitted here. In this case, the assisting force and the braking force may be set to the initial set value determined in advance. In this way, the time and effort of a user to specify the user ID can be omitted. Even though the processes from step S 51  to S 52  are omitted in one or more embodiments of the present example, the user can be determined from the characteristics of the braking operation and a user mode corresponding to the user can be set automatically. 
     Subsequently, the controller  80  may monitor whether the mobile object  1  is in a propelling state (step S 53 ). When the mobile object  1  is in a propelling state (Y in step S 53 ), the controller  80  may read a detected value of the current pressure sensor  72  (step S 54 ). 
     Then, the controller  80  may determine whether the detected value of the pressure sensor  72  exceeds the threshold α 1  (step S 55 ). As a result of the determination, when the detected value does not exceed the threshold α 1  (N in step S 55 ), the controller  80  may repeat the operation of the step  553 . On the other hand, when the detected value exceeds the threshold α 1  (Y in step S 55 ), the controller  80  may determine that the braking operation is activated (step S 56 ), and execute the brake control operation (step S 57 ). 
     By performing the brake control operation, a motor  911  may reduce the rotation gradually. When the rotation speed of the motor  911  (or the drive wheel  31 ) becomes zero or a sufficiently small value, the purpose of the brake control operation at that time is achieved. 
     Further, the controller  80  may acquire information (information relating to characteristics of the current braking operation) corresponding to the “operation force” and “operation time” based on the output of the pressure sensor  72  when the current braking operation is performed. Then, the controller  80  may compare the information stored in the memory  75  and the acquired information to determine the user who has performed the current braking operation by determining which user has the most similar characteristics of the braking operation to the characteristics of the current braking operation (step S 58 ). 
     Subsequently, the controller  80  may repeat the process of step S 53  when the current braking operation is performed by the normal user (user of the current setting user mode) (Y in step S 59 ). On the other hand, when the current braking operation is not performed by the normal user (N in step S 59 ), the controller  80  may perform a resetting (change setting) of the user mode so that the user mode of the user who has performed the current braking operation is set (step S 60 ). Thereafter, the controller  80  may repeat the operation of step S 53 . 
     The process of step S 58  may be executed only when the difference between the characteristics of the current braking operation and the characteristics of the previous braking operation is relatively large. In this case, when the difference is relatively small, the controller  80  may consider that the current braking operation has been performed by the normal user, and the process of step S 53  may be repeated by omitting the process of step S 58 . 
     By performing the series of operations described above (steps S 51  to S 60 ), the brake operation can be carried out even by a weak user. Further, according to one or more embodiments of the present example, an appropriate user mode (user mode appropriate to the current user) can be set automatically by using the differences of the braking operation by each user. 
     6. OTHER EXAMPLES 
     As described above, the mobile object  1  of each example (except one or more embodiments of the third example) may comprise a vehicle body  10 , a grip  26  to be held by the user and is attached to the vehicle body  10 , a pressure sensor  72  (detector) that detects a gripping force, a wheel  30  used to propel the vehicle body  10 , a wheel driver  91  that drives the wheel  30  electrically, and a controller  80  that controls an electromotive drive to perform power assistance when the user walks while propelling or moving the vehicle body  10  by holding the grip  26 . 
     The controller  80  may perform the brake control operation to decelerate the rotation speed of the wheel  30  when the detected value of the pressure sensor  72  satisfies the predetermined condition. Therefore, the mobile object  1  may enable a braking operation while having the power-assist function. 
     Furthermore, in the mobile object  1  according to one or more embodiments of the first example, the controller  80  may perform the brake control operation when the detected value of the pressure sensor  72  exceeds a predetermined threshold α 1  (first threshold). Therefore, the user can apply the braking operation even in urgent situations. 
     Furthermore, in the mobile object  1  according to one or more embodiments of the second example, the controller  80  may perform the brake control operation when the detected value of the pressure sensor  72  is lower than a predetermined threshold α 2  (first threshold). Therefore, one or more embodiments of the present invention may safely prevent a situation where the mobile object  1  is driven against the will of the user. 
     Moreover, the mobile object  1  according to one or more embodiments of the fourth example may comprise a threshold setting unit that sets the threshold α 1  to be updated. The threshold setting unit may store a history of the detected values of the pressure sensor  72  when the detected values exceed the threshold α 1 , and update the setting of the threshold α 1  based on the history. Therefore, even when a user&#39;s grip strength changes due to changes in the user&#39;s physical condition (e.g., aging) or when the mobile object  1  deteriorates through repeated use, the user can still use the mobile object  1  comfortably. 
     The mobile object  1  may comprise a mode setting unit that sets any of a plurality of user modes, and the threshold setting unit sets the threshold al for each user mode. Therefore, even though there may be an individual difference in gripping strength by each user, any user can use the mobile object  1  comfortably. 
     Further, the mobile object  1  according to one or more embodiments of the fifth example may comprise a functional unit (mode setting unit) that sets any of a plurality of user modes. The mode setting unit may determine the user mode to be set based on reference information relating to the characteristics of the braking operation prepared in advance for each user mode and an output of the pressure sensor  72  when exceeding the threshold α 1 . Therefore, an appropriate user mode can be set automatically by using the differences of the braking operation by each user. 
     Furthermore, with the mobile object  1 , a pattern of the electromotive drive force (e.g., assisting force and braking force) of the wheel  30  may be determined by a controller, and the electromotive drive may be performed in accordance with the pattern of the set user mode. Therefore, even though an appropriate electromotive force is different by each user, any user can use the mobile object  1  comfortably. 
     Moreover, the mobile object  1  of one or more embodiments of the third example may comprise a vehicle body  10 , a grip  26  held by a user attached to the vehicle body  10 , a wheel used for propelling or moving the vehicle  10 , a wheel driver  91  that drives the wheel  30  electrically, a brake lever  25  operated by the user when applying a wire brake, and a controller  80  that controls an electromotive drive to perform power assistance when the user walks while propelling or moving the vehicle body  10  by holding the grip  26 . 
     In addition, the controller  80  may control the electromotor to decelerate the rotation speed of the wheel  30  when the operation amount of the brake lever  25  exceeds the default value. Therefore, the controller may enable a braking operation while having the power-assist function. Furthermore, the controller may help prevent a situation where an opposing force is generated simultaneously such as applying the wire brake when the power assistance is performed. 
     A method for controlling the mobile object  1  by the controller  80  or the like may comprise, a first step that drives the wheel  30  electrically to perform power assistance when the user walks while propelling or moving the vehicle body  10  by holding the grip  26 , a second step that detects the gripping force, and a third step that controls the electromotive drive to decelerate the rotation speed of the wheel  30  when the detected value satisfies the predetermined condition. 
     A mobile object  1  was described as an example in various embodiments; however, the application of the present invention is not limited thereto and can be widely applied to even other manually propelled vehicles (such as baby carriages, dollies, wheelchairs, and the like). 
     The various technical features disclosed herein may have various modifications without departing from the scope of its technical creation other than the examples described above. The embodiments described above should be considered as examples only; the technical scope of the present invention is to be limited by the scope of claims only. Further, one of ordinary skill in the art would understand and appreciate that all modifications that have an equivalent meaning or fall within the scope of the claims are included. Furthermore, one or more embodiments of the present invention are applicable to manually propelled vehicles and the like. Furthermore, those of ordinary skill in the art would appreciate that certain “units,” “parts,” “elements,” or “portions” of one or more embodiments of the present invention may be implemented by a circuit, processor, etc. using known methods. 
     DESCRIPTION OF THE REFERENCE NUMERALS 
       1  mobile object (e.g., ambulatory assist vehicle) 
       10  vehicle body 
       11  strut member 
       20  handle 
       21  handlebar 
       22  middle handle 
       23  handle holder 
       231  first contact surface (forward side) 
       232  second contact surface (rearward side) 
       233  guide pin 
       24  neutral holding section 
       25  brake lever 
       25   a  pivotal axis 
       25   b  brake wire 
       26  ( 26 L,  26 R) grip (left, right) 
       30  wheel 
       31  ( 31 L,  31 R) drive wheel (left, right) 
       32  ( 32 L,  32 R) idler wheel (left, right) 
       40  baggage compartment 
       50  backrest 
       60  user interface 
       61  manual operation 
       62  notification 
       70  sensor 
       71  handle sensor 
       711 ˜ 714  first to fourth sensors 
       72  ( 72 L,  72 R) left side pressure sensor (left, right) 
       73  brake lever operation amount detector 
       75  memory 
       80  controller 
       81  processor 
       82  wheel drive controller 
       90  electromotor 
       91  ( 91 L,  91 R) wheel driver (left, right) 
       911  ( 911 L,  911 R) motor (left, right) 
       912  ( 912 L,  912 R) motor driver (left, right) 
       913  ( 913 L,  913 R) current sensor (left, right) 
       914  ( 914 L,  914 R) rotation angle sensor (left, right) 
       100  power supply