Superior limb assist device

Abstract

To provide a superior limb assist device which allows tensile force to be efficiently utilized as assist force, by driving an actuator using output according to a stage of load lifting operation.SOLUTION: A superior limb assist device 1 for supporting lifting of a load by a user includes: a wire 3 of which one end is connected to the arm of a user; an actuator 2 which is connected to the other end of the wire 3 and is capable ot transmitting tensile force to the wire 3 using arbitrary output; a grip detection sensor 10 capable of detecting either a gripping state where a load has been gripped by the user or a release state where the load is not gripped by the user; and a control part 15 which gradually increases or decreases the output of the actuator 2 according to a detection result of the grip detection sensor 10.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an upper limb assist device that assists a user in lifting an object. [Background technology]

[0002] In recent years, upper limb assist devices that assist users in lifting objects have been widely developed. A wire is connected to the upper limb assist device, and a member called an end effector provided at the tip of the wire is attached to the user's arm. As a result, the driving force of an actuator generated in the upper limb assist device is transmitted as a pulling force to the user's arm via the wire and the end effector (see, for example, Patent Document 1).

[0003] Here, in order to time the transmission of the tensile force to the user's arm, a gripping detection sensor capable of detecting whether the luggage is in a gripped state (i.e., gripped by the user) or in a released state (i.e., not gripped) is provided, for example, on the end effector. When the gripping detection sensor detects that the luggage has changed from a released state to a gripped state, a control unit that controls the operation of the actuator drives the actuator at maximum output. On the other hand, when the gripping detection sensor detects that the luggage has changed from a gripped state to a released state, the control unit stops driving the actuator. In this way, the tensile force is transmitted to the user's arm only while the luggage is being gripped. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-094650 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional upper limb assist device, there is a problem that the pulling force transmitted to the user's arm is not efficiently used as an assisting force to assist the lifting of the load. That is, the magnitude of the assisting force required by the user differs depending on the stage of the lifting of the load. However, in the conventional upper limb assist device, since the control unit either drives the actuator at maximum output or stops it, depending on the stage from when the user lifts the load to when he puts it down, an unnecessarily large pulling force acts on the user's arm, and the user cannot use all of the pulling force as an assisting force.

[0006] The present invention has been devised in consideration of these circumstances, and its purpose is to provide an upper limb assist device that can efficiently utilize pulling force as an assisting force by driving an actuator with an output that corresponds to the stage of the load lifting action. [Means for solving the problem]

[0007] An upper limb assist device according to one aspect of the present invention is an upper limb assist device that assists a user in lifting a load, and is characterized in comprising a wire having one end connected to the user's arm, an actuator connected to the other end of the wire and capable of transmitting a tensile force to the wire at an arbitrary output, a gripping detection sensor that can detect whether the load is in a gripped state in which it is being gripped by the user or in a released state in which it is not being gripped, and a control unit that gradually increases or decreases the output of the actuator based on the detection result of the gripping detection sensor.

[0008] In addition, in an upper limb assist device according to one aspect of the present invention, when the grip detection sensor detects that the luggage has changed from a released state to a gripped state, the control unit may increase the output of the actuator from a first output to a second output, and then further increase the output from the second output to a third output.

[0009] In addition, in an upper limb assist device according to one aspect of the present invention, the device further includes a posture detection sensor capable of detecting the inclination of the user's body, and when the gripping detection sensor detects that the luggage has changed from a released state to a gripped state, if the posture detection sensor detects that the user's body is leaning forward at more than a first angle from the vertical, the control unit may select an on-floor luggage mode for lifting the luggage from the floor, and if the posture detection sensor detects that the user's body is not leaning forward at more than the first angle from the vertical, the control unit may select an on-table luggage mode for lifting the luggage from a table.

[0010] In addition, in an upper limb assist device according to one aspect of the present invention, when the on-floor luggage mode is selected, the control unit may increase the output of the actuator from the second output to the third output when the posture detection sensor detects that the user's body has leaned backward by a second angle from the time when the gripping detection sensor detects that the luggage has changed from a released state to a gripped state.

[0011] In addition, in an upper limb assist device according to one aspect of the present invention, a timer capable of measuring an elapsed time is further provided, and when the on-table luggage mode is selected, the control unit may increase the output of the actuator from the second output to the third output when the timer detects that a first time has elapsed since the grip detection sensor detected that the luggage has changed from a released state to a gripped state.

[0012] In addition, in an upper limb assist device according to one aspect of the present invention, the gripping detection sensors may be provided on the left arm side and the right arm side of the user, respectively, and the control unit may increase the output of the actuator from the first output to the second output when the gripping detection sensors on both the left arm side and the right arm side of the user detect that the luggage has changed from a released state to a gripped state.

[0013] In addition, in an upper limb assist device according to one aspect of the present invention, the device further includes a posture detection sensor capable of detecting a tilt of the user's body, and when the posture detection sensor detects that the user's body has tilted forward by a third angle while the gripping detection sensor detects that the luggage is in a gripping state, the control unit may reduce the output of the actuator from a fourth output to a fifth output, and then when the gripping detection sensor detects that the luggage has changed from a gripped state to a released state, the control unit may further reduce the output of the actuator to a sixth output.

[0014] In addition, in an upper limb assist device according to one aspect of the present invention, the control unit may gradually reduce the output of the actuator from the fifth output to a seventh output greater than the sixth output during the period from when the posture detection sensor detects that the user's body has leaned forward by a third angle to when the grip detection sensor detects that the luggage has changed from a gripped state to a released state.

[0015] In addition, in an upper limb assist device according to one aspect of the present invention, the control unit may increase the output of the actuator to an eighth output when the posture detection sensor detects that the user's body has leaned forward by a third angle and then leaned backward by a fourth angle while the gripping detection sensor detects that the luggage is being gripped.

[0016] In addition, in an upper limb assist device according to one aspect of the present invention, the grip detection sensors may be provided on the left arm side and the right arm side of the user, respectively, and the control unit may reduce the output of the actuator to the sixth output when the grip detection sensors on both the left arm side and the right arm side of the user detect that the luggage has changed from a gripped state to a released state. Effect of the Invention

[0017] According to an upper limb assist device according to one aspect of the present invention, the actuator is driven with an output according to the stage of the load lifting motion, so that the pulling force can be efficiently used as an assist force. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic perspective view of an upper limb assist device 1 according to a first embodiment of the present invention, as viewed from the front side. [Diagram 2] 1 is a schematic rear view of an upper limb assist device 1 according to a first embodiment of the present invention. [Diagram 3] 1 is a block diagram showing a functional configuration of an upper limb assist device 1 according to a first embodiment of the present invention. [Figure 4] 10 is a flowchart showing a process flow regarding two-stage output increase control of the right actuator 2R. [Diagram 5] 11 is a graph showing the relationship between the elapsed time and the output of the right actuator 2R during two-stage output increase control. [Figure 6] 13 is a flowchart showing the process flow of the first-stage increase process SA. [Figure 7] 13 is a flowchart showing the process flow of an operation mode selection process SB. [Figure 8] 13 is a flowchart showing the flow of the second stage increase process SC when the above-floor luggage mode is selected. [Figure 9] 13 is a flowchart showing the process flow of the second stage increase process SC when the on-platform baggage mode is selected. [Figure 10] 13 is a flowchart showing the process flow of a first-stage increase process SD when the left-right synchronous control mode is adopted. [Figure 11] 13 is a flowchart showing a process flow of three-stage output reduction control of a right actuator 2R in an upper limb assist device 20 according to a second embodiment of the present invention. [Figure 12] 11 is a graph showing the relationship between the elapsed time and the output of the right actuator 2R during three-stage output reduction control. [Figure 13] 13 is a flowchart showing the process flow of a first-stage reduction process SE. [Figure 14] 13 is a flowchart showing the flow of a second-stage reduction process SF. [Figure 15] 13 is a flowchart showing the process flow of the third-stage reduction process SG. [Figure 16] 10 is a flowchart showing a process flow for output recovery control of the right actuator 2R. [Figure 17] 11 is a graph showing the relationship between the elapsed time and the output of the right actuator 2R during output return control. [Figure 18] 13 is a flowchart showing the flow of the re-increase process SH. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an upper limb assist device according to an embodiment of the present invention will be described with reference to the drawings.

[0020] (Configuration of the upper limb assist device according to the first embodiment) First, the configuration of an upper limb assist device according to a first embodiment of the present invention will be described. The upper limb assist device according to this embodiment is characterized in that it gradually increases the output of an actuator when a user lifts a load. Figs. 1 and 2 show the configuration of an upper limb assist device 1 according to the first embodiment, Fig. 1 being a schematic perspective view seen from the front side, and Fig. 2 being a schematic rear view. The upper limb assist device 1 includes an actuator 2, a wire 3, and an end effector 4.

[0021] The actuator 2 generates a tensile force to be transmitted to the user's arm. As shown by the dashed line in FIG. 2, the actuator 2 has an electric motor 5 and a pulley 6. The electric motor 5 is driven and controlled to rotate at an arbitrary output depending on the stage of the user's lifting action. The pulley 6 is fixed to the rotating shaft of the electric motor 5, and rotates in conjunction with the rotation of the electric motor 5. The actuator 2 thus configured is held on the user's back while being housed inside a backpack 7. Inside the backpack 7, a left actuator 2L that generates a tensile force to be transmitted to the user's left arm and a right actuator 2R that generates a tensile force to be transmitted to the user's right arm are provided.

[0022] The wire 3 transmits the tensile force generated by the actuator 2 to the end effector 4. The wire 3 is formed of a string-like material made of chemical fiber or the like. One end of the wire 3 configured in this manner is wound around the periphery of a pulley 6 constituting the actuator 2, as shown by the dashed line in FIG. 2. The wire 3 is then routed from the back of the user across the shoulders to the front side, and the other end is connected to the end effector 4, which will be described later, as shown in FIG. 1. A pair of left and right wires 3 are provided corresponding to the left and right arms of the user, respectively.

[0023] The end effector 4 is attached to the user's arm and transmits the tensile force of the actuator 2 to the user's arm. As shown in FIG. 1, the end effector 4 has a finger attachment part 7 and a wrist attachment part 8. The finger attachment part 7 is attached to the user's finger and serves to transmit the tensile force of the actuator 2 to the user's finger. A grip detection sensor 10, which will be described later, is attached to the finger attachment part 7. On the other hand, the wrist attachment part 8 is attached to the user's wrist and serves to transmit the tensile force of the actuator 2 to the user's arm. The end effector 4 thus configured includes a pair of left and right end effectors 4 corresponding to the left and right arm sides of the user. The configuration of the end effector 4 is not limited to this embodiment, and the design can be appropriately changed within a range in which the tensile force can be transmitted to the user's arm.

[0024] Next, a description will be given of the functional configuration of the upper limb assist device 1. Fig. 3 is a block diagram showing the functional configuration of the upper limb assist device 1 according to the first embodiment. The upper limb assist device 1 includes an actuator 2, a grip detection sensor 10, a posture detection sensor 11, a timer 12, a storage unit 13, a communication bus 14, and a control unit 15.

[0025] The actuator 2 has the role and configuration as described above, and as shown in FIG. 3, includes a left actuator 2L and a right actuator 2R.

[0026] The grip detection sensor 10 detects whether the load is in a gripped state, that is, gripped by the user, or in a released state, that is not gripped. The grip detection sensor 10 is a so-called pressure sensor, and is attached to the finger attachment part 7 of the end effector 4 as shown in Fig. 1. The grip detection sensor 10 detects whether the load is in a gripped state or a released state based on a pressure change of a fluid when the load is pinched between the user's fingers and the load or released, and outputs the detection result to the control unit 15. The grip detection sensor 10 has a left grip detection sensor 10L attached to the left hand of the user and a right grip detection sensor 10R attached to the right hand, as shown in Fig. 3.

[0027] The posture detection sensor 11 serves to detect when the user has prepared his / her body for lifting or lowering the load. This posture detection sensor 11 is, for example, an inertial measurement unit (IMU). As shown by the dashed line in FIG. 2, this posture detection sensor 11 is installed inside the backpack 7 held on the user's back. In this way, the posture detection sensor 11 detects the inclination of the user's upper body and outputs the detection result to the control unit 15.

[0028] The timer 12 measures the elapsed time from an arbitrary reference time and outputs the measurement result to the control unit 15. The memory unit 13 stores various programs and temporary information, as well as various thresholds and setting values ​​used to control the actuator 2. The communication bus 14 electrically connects the various components constituting the upper limb assist device 1 to each other. The control unit 15 receives the detection results of the grip detection sensor 10 and the posture detection sensor 11 and the measurement result of the timer 12 via the communication bus 14, and controls the operation of each component including the actuator 2 based on the inputs.

[0029] (Actuator output increase control and its action and effect) Next, the two-stage output increase control of the right actuator 2 during lifting of a load and its action and effect will be described with respect to the upper limb assist device 1 according to the first embodiment of the present invention. FIG. 4 is a flowchart showing the flow of processing for the two-stage output increase control of the right actuator 2R. FIG. 5 is a graph showing the relationship between the elapsed time during the two-stage output increase control and the output of the right actuator 2R. Note that in this embodiment, a "left and right independent control mode" is adopted in which the left actuator 2L and the right actuator 2R are independently controlled, and the right actuator 2R will be described here. Although the description will be omitted here, the same processing is executed for the left actuator 2L as for the right actuator 2R.

[0030] 4, when the two-stage output increase control of the right actuator 2R is started, the control unit 15 first executes a "first-stage increase process SA", then executes an "operation mode selection process SB", and finally executes a "second-stage increase process SC", thereby completing the two-stage output increase control of the actuator 2. Each process will be described in detail below.

[0031] First, the "first-stage increase process SA" shown in FIG. 4 is a process for increasing the output of the right actuator 2R by a certain degree. FIG. 6 is a flowchart showing the process flow of the first-stage increase process SA. When the first-stage increase process SA is started, the control unit 15 first detects that the user has gripped a released baggage with the right arm, in other words, that the right side of the baggage has changed from the released state to the gripped state. Specifically, the control unit 15 acquires the output of the right grip detection sensor 10R (step S1), and determines whether the right side of the baggage is in the released state or not based on the detection result (step S2). As a result, if it is determined that the baggage is not in the released state (S2: No), the control unit 15 returns to step S1 and waits until the baggage is in the released state. On the other hand, if it is determined that the baggage is in the released state (S2: Yes), the control unit 15 continues to acquire the output of the right grip detection sensor 10R (step S3), and determines whether the right side of the baggage is in the gripped state or not based on the detection result (step S4). As a result, if it is determined that the gripping state is not reached (S4: No), the process returns to step S3 and waits until the gripping state is reached.

[0032] Thereafter, if it is determined in step S4 that the right side of the luggage has been gripped (S4: Yes), the control unit 15 increases the output of the right actuator 2R from 0% (corresponding to the "first output" of the present invention) to 30% (corresponding to the "second output" of the present invention) (step S5), as shown as time T1 in FIG. 5. This ends the first-stage increase process SA. Note that the "%" used for output in this specification means a ratio compared to the maximum output of the right actuator 2R being 100%.

[0033] Next, the "operation mode selection process SB" shown in Fig. 4 is a process that selects an operation mode by determining whether the lifting operation of the luggage is an operation of lifting luggage placed on the floor or an operation of lifting luggage placed on a platform. Fig. 7 is a flowchart showing the processing flow of the operation mode selection process SB. Note that "on the platform" in this specification means a platform having a luggage placement surface higher than the floor surface, and the "platform" here is intended to broadly include a desk, chair, table, workbench, stairs, etc.

[0034] When the operation mode selection process SB is started, as shown in FIG. 7, the control unit 15 first acquires the output of the posture detection sensor 11 (step S6). Then, based on the detection result, the control unit 15 judges whether the upper body of the user is inclined forward by more than 30° (corresponding to the "first angle" according to the present invention) from the vertical direction (step S7). As a result, when it is judged that the upper body of the user is inclined forward by more than 30° (S7: Yes), the control unit 15 judges that the operation is an operation of lifting a load from the floor, and selects the "load mode on the floor" (step S8). On the other hand, when it is judged that the upper body is not inclined forward by more than 30°, that is, the forward inclination angle is 30° or less (S7: No), the control unit 15 judges that the operation is an operation of lifting a load from a platform, and selects the "load mode on the platform" (step S9). This ends the operation mode selection process SB. In this specification, "inclining forward" means a state in which the upper body of the user is inclined in a direction in which the front side of the upper body is brought closer to the floor surface, or an operation in which the user rotates the body in that direction.

[0035] Finally, the "second-stage increase process SC" shown in FIG. 4 is a process for further increasing the output of the right actuator 2R. FIG. 8 is a flowchart showing the flow of the second-stage increase process SC when the on-floor baggage mode is selected. When the second-stage increase process SC is started, the control unit 15 first acquires the output of the right grip detection sensor 10R (step S10), and then acquires the output of the posture detection sensor 11 (step S11). Then, based on these detection results, the control unit 15 determines whether the user has prepared a posture for lifting the baggage while gripping the right side of the baggage. Specifically, the control unit 15 determines whether the right side of the baggage is in a gripping state and whether the upper body of the user has tilted backward by 5° (corresponding to the "second angle" according to the present invention) or more since the output of the posture detection sensor 11 was previously acquired in step S5 (step S12). As a result, if the control unit 15 determines that the right side of the luggage is released or the user's upper body is not tilted backward by 5° or more (S12: No), the control unit 15 determines that the user has stopped lifting the right side of the luggage or has not sufficiently prepared his / her body to lift the luggage, and returns to step S10 to wait until the user's upper body is tilted backward by 5° or more. On the other hand, if the control unit 15 determines that the right side of the luggage is in a gripping state and that the user's upper body is tilted backward by 5° or more (S12: Yes) as a result of the determination in step S12, the control unit 15 determines that the user has sufficiently prepared his / her body to lift the luggage by sitting down while gripping the right side of the luggage, and increases the output of the right actuator 2R from 30% (corresponding to the "second output" according to the present invention) to 100% (corresponding to the "third output" according to the present invention) (step S13), as shown as time T2 in FIG. 5. This ends the second-stage increase process SC of the on-floor luggage mode. In this specification, "leaning backward" refers to the movement of the user's upper body rotating in a direction in which the front side of the upper body moves away from the floor surface.

[0036] On the other hand, FIG. 9 is a flowchart showing the flow of the second-stage increase process SC when the platform baggage mode is selected. When the second-stage increase process SC is started, the control unit 15 first acquires the output of the right grip detection sensor 10R (step S14), and then acquires the measurement result of the timer 12 (step S15). Then, the control unit 15 judges whether a certain time has passed while the user is gripping the right side of the baggage. Specifically, the control unit 15 judges whether the right side of the baggage is in a gripping state, and whether 0.2 seconds (corresponding to the "first time" according to the present invention) have passed since it was detected in step S4 that the right side of the baggage has changed from a released state to a gripped state (step S16). As a result, if the control unit 15 judges that the right side of the baggage is in a released state or that 0.2 seconds have not passed (S16: No), the control unit 15 judges that the user has stopped lifting the right side of the baggage or has not sufficiently prepared his / her body to lift the baggage, and returns to step S14 to wait until 0.2 seconds have passed. On the other hand, if it is determined in step S16 that the right side of the luggage is being gripped and 0.2 seconds have elapsed (S16: Yes), the control unit 15 determines that the user is gripping the right side of the luggage and has fully prepared his / her body for lifting, and increases the output of the right actuator 2R from 30% to 100% (step S17), as shown by the two-dot chain line at time T3 in Fig. 5. This ends the second stage increase process SC of the platform luggage mode.

[0037] The two-stage output increase control of the actuator 2 in the upper limb assist device 1 according to the first embodiment has the advantage of preventing the problem of the so-called "stumbling" in which the user is about to fall forward when lifting a load. That is, in the conventional upper limb assist device, when the grip detection sensor detects that the load has changed from a released state to a gripped state, the control unit drives the actuator at maximum output, that is, increases the output of the actuator from 0% to 100% in one go. According to this output increase control, after the user leans his / her upper body slightly forward to grip the load, before the user settles down and fully prepares for lifting, the maximum output of the actuator acts on the user's arm as a pulling force. This causes a problem in which the user loses to the reaction force of the pulling force and stumbles forward. In this regard, according to the two-stage output increase control of the actuator 2 according to the first embodiment of the present invention, when the control unit 15 detects that the luggage has changed from the released state to the gripped state, it first increases the output of the actuator 2 from 0% to 30%, and then further increases the output of the actuator 2 from 30% to 100% when the user's upper body tilts backward by 5° or more in the floor luggage mode, or when 0.2 seconds have passed in the platform luggage mode. In this way, since the output of the actuator 2 is controlled to be increased in two stages, an unnecessarily large pulling force is not applied to the user's arm until the user is fully prepared to lift the luggage. Therefore, it is possible to prevent the user from stumbling forward due to the reaction force of the pulling force. Furthermore, there is an advantage that the pulling force can be efficiently used as an assisting force by driving the actuator 2 with an output according to the stage of the luggage lifting operation.

[0038] (Modification of the first embodiment) The technical scope of the present invention is not limited to the first embodiment described above, and various modifications can be made without departing from the spirit of the present invention as defined by the claims. For example, the following modifications of the first embodiment of the present invention are possible.

[0039] In this embodiment, the actuator 2 is configured by an electric motor 5 and a pulley 6, as shown in Fig. 2. However, the actuator 2 according to the present invention is not limited to this embodiment, and as long as it is possible to apply a tensile force to the wire 3, it is possible to use an actuator 2 that generates power by any conventionally known method, such as a hydraulic type, a pneumatic type, an electromagnetic type, or a piezoelectric type.

[0040] In this embodiment, a pressure sensor that detects a pressure change of a fluid is used as the grip detection sensor 10. However, the grip detection sensor 10 according to the present invention is not limited to this embodiment, and any conventionally known sensor capable of detecting the grip of a load by a user, such as a pressure sensor that detects a pressure change by utilizing a piezoresistance effect, can be used. In this embodiment, the grip detection sensor 10 is attached to the finger attachment part 7 of the end effector 4 as shown in FIG. 1. However, the grip detection sensor 10 may be provided at a position other than the finger attachment part 7 of the end effector 4. In addition, as long as it is possible to detect whether the load is in a released state or a gripped state, the grip detection sensor 10 can be attached to the arm of the user as a separate member from the end effector 4, or it can be attached to the side of the load instead of the arm of the user.

[0041] In this embodiment, an inertial measurement unit is used as the posture detection sensor 11. However, the posture detection sensor 11 according to the present invention is not limited to this embodiment, and any conventionally known type of sensor capable of detecting the inclination of the user's body can be used. Also, in this embodiment, as shown in FIG. 2, the posture detection sensor 11 is installed inside the backpack 7 to detect the inclination of the user's upper body. However, the installation position of the posture detection sensor 11 is not limited to this embodiment, and can be changed to any part of the user's body where the inclination is to be detected.

[0042] In this embodiment, the first output according to the present invention is set to 0%, the second output is set to 30%, and the third output is set to 100%. The first angle according to the present invention is set to 30°, and the second angle is set to 5°. The first time according to the present invention is set to 0.2 seconds. However, these set values ​​are not limited to this embodiment, and can be appropriately changed according to the age, sex, personality, and other circumstances of the user. For example, it is also possible to set the first output, that is, the output of the actuator 2 when the luggage is in a released state, to a value slightly larger than 0%. In this way, if a weak tension is applied to the wire 3 wound around the circumferential surface of the pulley 6 when the luggage is in a released state, the occurrence of slack in the wire 3 is reduced, which has the advantage that the wire 3 is less likely to become entangled when the output of the actuator 2 is increased.

[0043] In this embodiment, a two-stage output increase control is performed in which the output of the actuator 2 is increased in two stages, a first-stage increase process SA and a second-stage increase process SB, as shown in Fig. 4. However, the present invention is characterized in that the output of the actuator 2 is increased in stages, and the manner in which this is done is not limited to this embodiment, and it is also possible to increase the output in multiple stages of three or more stages.

[0044] In this embodiment, a "left-right independent control mode" is adopted in which the output increase control of the left actuator 2L and the output increase control of the right actuator 2R are performed independently. This left-right independent control mode has the advantage that, when there is a time difference between the right arm and the left arm of the user in grasping a load, unnecessary pulling force is not applied to the arm that is not yet grasping the load. However, instead of this embodiment, as a mode of the output increase control of the left and right actuators 2, a "left-right synchronous control mode" can be adopted in which the output increase control of the right actuator 2R and the output increase control of the left actuator 2L are synchronized.

[0045] FIG. 10 is a flowchart showing the flow of the first-stage increase process SD in the case where the left-right synchronous control mode is adopted. When the first-stage increase process SD is started, the control unit 15 first detects that both the left and right sides of the luggage have changed from a released state to a gripped state. Specifically, the control unit 15 first acquires the output of the right grip detection sensor 10R (step S18) and also acquires the output of the left grip detection sensor 10L (step S19). Then, the control unit 15 judges whether both the left and right sides of the luggage are in a released state (step S20). As a result, if it is judged that either the left or right side or both the left and right sides are not in a released state (S20: No), the control unit 15 returns to step S18 and waits until both the left and right sides are in a released state. On the other hand, if it is judged that both the left and right sides are in a released state (S20: Yes), the control unit 15 acquires the output of the right grip detection sensor 10R (step S21) and also acquires the output of the left grip detection sensor 10L (step S22). Then, the control unit 15 judges whether both the left and right sides of the luggage have changed to a gripped state (step S23). As a result, if it is determined that either the left or right side or both the left and right sides are not in a gripping state (S23: No), the process returns to step S21 and waits until both the left and right sides are in a gripping state. After that, if it is determined in step S23 that both the left and right sides of the luggage are in a gripping state (S23: Yes), that is, if it is determined that the left side of the luggage is in a gripping state and the right side is also in a gripping state, the control unit 15 increases the output of both the right actuator 2R and the left actuator 2L from 0% to 30% (step S24). This ends the first-stage increase process SD. According to this left-right synchronous control mode, the same pulling force is applied to the right arm and the left arm of the user at the same time, which has the advantage that the user can easily maintain left-right balance.

[0046] (Configuration of the upper limb assist device according to the second embodiment) Next, the configuration of an upper limb assist device according to a second embodiment of the present invention will be described. The upper limb assist device according to this embodiment is characterized in that it gradually reduces the output of the actuator 2 when the user is lifting a load (in other words, when the user is unloading the load). The upper limb assist device 20 of this embodiment has the same configuration as the upper limb assist device 1 of the first embodiment shown in Figures 1 and 2, so the description of each part will be omitted here and the same reference numerals as those of the first embodiment will be used.

[0047] (Actuator output reduction control and its effects) Next, the three-stage output reduction control of the right actuator 2R during the lifting and lowering operation of a load will be described with respect to the upper limb assist device 20 according to the second embodiment of the present invention, and its action and effect. FIG. 11 is a flowchart showing the process flow of the three-stage output reduction control of the right actuator 2R. FIG. 12 is a graph showing the relationship between the elapsed time during the three-stage output reduction control and the output of the right actuator 2R. Note that this embodiment also employs a "left and right independent control mode" in which the left actuator 2L and the right actuator 2R are independently controlled, and the right actuator 2R will be described here.

[0048] As shown in Fig. 11, when the three-stage output reduction control of the right actuator 2R is started, the control unit 15 first executes the "first stage reduction process SE", then executes the "second stage reduction process SF", and finally executes the "third stage reduction process SG", thereby completing the three-stage output reduction control of the right actuator 2R. Each process will be described below in detail, but since the first stage reduction process SE is the same as in the second embodiment, it is designated by the same reference numerals as in the second embodiment and its description will be omitted here. Note that in this embodiment as well, the right actuator 2R when the "left and right independent control mode" is adopted will be described.

[0049] The "first-stage reduction process SE" shown in FIG. 11 is a process for reducing the output of the right actuator 2R by a certain degree. FIG. 13 is a flowchart showing the process flow of the first-stage reduction process SE. When the first-stage reduction process SE is started, the control unit 15 first detects the inclination of the upper body of the user in the initial state. That is, the control unit 15 acquires the output of the posture detection sensor 11 (step S30), and stores the detection result as an initial inclination value in the storage unit 13 shown in FIG. 3 (step S31). Next, the control unit 15 detects that the user has grasped the right side of the luggage and has prepared a posture for lowering it. Specifically, the control unit 15 first acquires the output of the right grip detection sensor 10R (step S32), and then acquires the output of the posture detection sensor 11 (step S33). Then, the control unit 15 determines whether the right side of the luggage is in a gripping state, and whether the upper body of the user has inclined forward by 30° (corresponding to the "third angle" according to the present invention) or more from the initial inclination value (step S34). As a result, if it is determined that the right side of the baggage is released or the user's upper body is not tilted forward by 30° or more from the initial tilt value (S34: No), the control unit 15 determines that the user has stopped lowering the right side of the baggage or has not sufficiently prepared his / her body to lower the baggage, and returns to step S32 to wait until the user's upper body is tilted forward by 30° or more from the initial tilt value. On the other hand, if it is determined that the right side of the baggage is in a gripping state and the user's upper body is tilted forward by 30° or more from the initial tilt value (S34: Yes) as a result of the determination in step S34, the control unit 15 determines that the user has sufficiently prepared his / her body to lower the baggage while gripping the right side of the baggage, and reduces the output of the right actuator 2R from 100% (corresponding to the "fourth output" of the present invention) to 40% (corresponding to the "fifth output" of the present invention) (step S35), as shown as time T4 in FIG. 12. This ends the first-stage reduction process SE.

[0050] The "second stage reduction process SF" shown in FIG. 11 is a process for gradually reducing the output of the right actuator 2R with the passage of time. FIG. 14 is a flowchart showing the process flow of the second stage reduction process SF. When the second stage reduction process SF is started, the control unit 15 first starts measuring time using the timer 12 (step S40) and starts reducing the output of the right actuator 2R at a speed of 50% / second (step S41). After that, the control unit 15 acquires the measurement result of the timer 12 (step S42) and judges whether 0.5 seconds have elapsed since the start of measurement (step S43). As a result, when it is judged that 0.5 seconds have elapsed (S43: No), the control unit 15 returns to step S41 and continues to further reduce the output of the right actuator 2R at a speed of 50% / second. On the other hand, if it is determined in step S42 that 0.5 seconds have passed since the start of measurement (S43: Yes), as shown as time T5 in FIG. 12, the output of the right actuator 2R has dropped to 15% (corresponding to the "seventh output" of the present invention), but the control unit 15 stops the output reduction of the right actuator 2R (step S44). This ends the second-stage reduction process SF. Note that the set value of the seventh output is not limited to this embodiment and can be changed as appropriate, as in the modified example of the first embodiment. In addition, in this second-stage reduction process SF, it is also possible to reduce the output of the right actuator 2R from 40% to 15% in one go by detecting the passage of a certain period of time, etc.

[0051] The "third stage decrease process SG" shown in FIG. 11 is a process for further decreasing the output of the right actuator 2R. FIG. 15 is a flowchart showing the process flow of the third stage decrease process SG. When the third stage increase process SG is started, the control unit 15 first acquires the output of the right grip detection sensor 10R (step S50). Then, the control unit 15 judges whether the right side of the luggage has become released or not based on the detection result (step S51). As a result, when the control unit 15 judges that the right side of the luggage has not become released and remains in the gripped state (S51: No), the control unit 15 returns to step S50 while keeping the output of the right actuator 2R at 15%, and waits until the right side of the luggage becomes released. On the other hand, when the control unit 15 judges that the right side of the luggage has become released as a result of the judgment in step S51 (S51: Yes), the control unit 15 reduces the output of the right actuator 2R from 15% to 0% (corresponding to the "sixth output" according to the present invention) as shown as time T6 in FIG. 12 (step S52). This ends the third stage reduction process SG.

[0052] According to the three-stage output reduction control of the actuator 2 in the upper limb assist device 20 according to the second embodiment, there is an advantage that it is possible to prevent the problem of an unnecessarily large tensile force acting on the user's arm during the lifting and lowering of a load. That is, in the conventional upper limb assist device, when the grip detection sensor detects that the load has been released from the gripped state, the control unit stops the actuator, that is, reduces the output of the actuator from 100% to 0% at once. According to such output reduction control, even after the user has tilted his / her upper body forward to prepare for the lifting and lowering, the maximum output of the actuator acts as a tensile force on the user's arm. Therefore, the user needs to lift and lower the load while resisting this maximum output of the actuator. In this regard, according to the three-stage output reduction control of the actuator 20 according to the second embodiment of the present invention, the output of the actuator 2 is reduced in three stages, so that after the user has prepared for the lifting and lowering of the load, an unnecessarily large tensile force does not act on the user's arm. Therefore, the user can lift and lower the load only by resisting a relatively small tensile force. In this way, the actuator 2 is driven with an output according to the stage of the load-lifting operation, which has the advantage that the pulling force can be efficiently used as an assisting force.

[0053] (Modification of the second embodiment) As in the modified example of the first embodiment, various design changes are possible for the actuator 2, the grip detection sensor 10, and the attitude detection sensor 11 of this embodiment. Also, as in the modified example of the first embodiment, the set values ​​of the third angle, the fourth output, the fifth output, and the sixth output according to the present invention are not limited to those of this embodiment and can be changed as appropriate.

[0054] In this embodiment, as shown in FIG. 12, the output of the right actuator 2R is controlled to be reduced in three stages. However, the present invention is characterized in that the output of the actuator 2 is reduced in stages, and the aspect is not limited to this embodiment, and it is also possible to reduce the output of the actuator 2 in two stages or four or more stages. For example, it is also possible to reduce the output of the right actuator 2R in two stages by omitting the execution of the second stage reduction process SF shown in FIG. 11 and executing the first stage reduction process SE and then the third stage reduction process SG. In this case, in the third stage reduction process SG, the output of the right actuator 2R may be reduced from 40% to 0%, as shown by the two-dot chain line in FIG. 12.

[0055] In this embodiment, as shown in Fig. 11 and Fig. 12, only the process of decreasing the output of the right actuator 2R is executed. However, if the user stops the operation of lowering the luggage midway, it is also possible to perform control to restore the output of the right actuator 2R. Fig. 16 is a flowchart showing the flow of the process for the output restoration control of the right actuator 2R. Fig. 17 is a graph showing the relationship between the elapsed time and the output of the right actuator 2R during the output restoration control.

[0056] As shown in Fig. 16, when the three-stage output reduction control of the right actuator 2R is started, the control unit 15 first executes the "first-stage reduction process SE", then executes the "second-stage reduction process SF", and finally executes the "re-increase process SH", thereby completing the output recovery control of the right actuator 2R. Note that the first-stage reduction process SE and the second-stage reduction process SF are the same as those in the second embodiment, so the same reference numerals as in the second embodiment are used and their explanation is omitted here. Note that in this modified example, the right actuator 2R when the "left and right independent control mode" is adopted will be explained.

[0057] The "re-increase process SH" shown in FIG. 16 is a process for increasing the output of the right actuator 2R again when the user lifts up the baggage that was being put down on the floor or the like. FIG. 18 is a flowchart showing the process flow of the re-increase process SH. When the re-increase process SH is started, the control unit 15 first detects the inclination of the upper body of the user in the initial state. That is, the control unit 15 acquires the output of the posture detection sensor 11 (step S60), and stores the detection result as an initial inclination value in the storage unit 13 shown in FIG. 3 (step S61). In this modification, as described in the first-stage decrease process SE, a 30° forward inclination state from the vertical direction is stored as this initial inclination value. Next, the control unit 15 detects that the user has adjusted his / her posture to lift the baggage again. Specifically, the control unit 15 acquires the output of the posture detection sensor 11 again (step S62). Then, the control unit 15 determines whether or not the user's upper body has tilted backward by 5° or more (corresponding to the "fourth angle" of the present invention) from the initial tilt value, in other words, whether or not the user's upper body has returned to a state inclined 25° forward from the vertical (step S63).

[0058] If the result of the judgment in step S63 is that the upper body of the user is not tilted backward by 5° or more from the initial tilt value (S63: No), the control unit 15 judges that the user is not sufficiently prepared to lift the luggage again, returns to step S62, and waits until the upper body of the user is tilted backward by 5° or more from the initial tilt value. On the other hand, if the result of the judgment in step S63 is that the upper body of the user is tilted backward by 5° or more from the initial tilt value (S63: Yes), the control unit 15 judges that the user is sufficiently prepared to lift the luggage again, and increases the output of the right actuator 2R from 15% to 100% (corresponding to the "eighth output" according to the present invention) (step S64), as shown as time T7 in FIG. 17. This ends the re-increase process SH. Note that the set values ​​of the fourth angle and the eighth output are not limited to the present embodiment and can be changed as appropriate, as in the modified example of the first embodiment. [Industrial Applicability]

[0059] The upper limb assist device according to the present invention can also be applied to a lower limb assist device that assists the user in walking or the like. [Explanation of symbols]

[0060] 1. Upper limb assist device 2 Actuators 3 Wire 10 Grasp detection sensor 11 Attitude detection sensor 12. Timer 15 Control section

Claims

1. An upper limb assist device that assists a user in lifting a load, A wire having one end connected to the arm of a user; an actuator connected to the other end of the wire and capable of transmitting a tensile force to the wire with an arbitrary output; a gripping detection sensor capable of detecting whether the luggage is in a gripped state in which it is gripped by a user or in a released state in which it is not gripped; A control unit that increases or decreases an output of the actuator in a stepwise manner based on a detection result of the grip detection sensor; An upper limb assist device comprising:

2. The upper limb assist device according to claim 1, characterized in that, when the grip detection sensor detects that the luggage has changed from a released state to a gripped state, the control unit increases the output of the actuator from a first output to a second output, and then further increases the output from the second output to a third output.

3. Further comprising a posture detection sensor capable of detecting the inclination of the user's body, The upper limb assist device according to claim 2, characterized in that when the grip detection sensor detects that the luggage has changed from a released state to a gripped state, if the posture detection sensor detects that the user's body is leaning forward at more than a first angle from the vertical, the control unit selects an on-floor luggage mode for lifting the luggage from the floor, and when the posture detection sensor detects that the user's body is not leaning forward at more than the first angle from the vertical, the control unit selects an on-table luggage mode for lifting the luggage from a table.

4. The upper limb assist device according to claim 3, characterized in that when the on-floor luggage mode is selected, the control unit increases the output of the actuator from the second output to the third output when the posture detection sensor detects that the user's body has leaned backward by a second angle from the time when the grip detection sensor detects that the luggage has changed from a released state to a gripped state.

5. Further comprising a timer capable of measuring an elapsed time, The upper limb assist device according to claim 3, characterized in that when the on-table luggage mode is selected, the control unit increases the output of the actuator from the second output to the third output when the timer detects that a first time has elapsed since the grip detection sensor detected that the luggage has changed from a released state to a gripped state.

6. The grip detection sensors are provided on the left arm side and the right arm side of the user, The upper limb assist device according to any one of claims 2 to 5, characterized in that when the grip detection sensors on both sides of the user's left arm and right arm detect that a load has changed from a released state to a gripped state, the control unit increases the output of the actuator from the first output to the second output.

7. Further comprising a posture detection sensor capable of detecting the inclination of the user's body, 2. The upper limb assist device according to claim 1, wherein when the posture detection sensor detects that the user's body has leaned forward by a third angle while the grip detection sensor detects that the luggage is being gripped, the control unit reduces the output of the actuator from a fourth output to a fifth output, and when the grip detection sensor subsequently detects that the luggage has changed from the gripped state to a released state, the control unit further reduces the output of the actuator to a sixth output.

8. The upper limb assist device according to claim 7, characterized in that the control unit gradually reduces the output of the actuator from the fifth output to a seventh output greater than the sixth output during the period from when the posture detection sensor detects that the user's body has leaned forward by a third angle to when the grip detection sensor detects that the luggage has changed from a gripped state to a released state.

9. The upper limb assist device according to claim 7 or 8, characterized in that when the posture detection sensor detects that the user's body has leaned forward by a third angle and then leaned backward by a fourth angle while the gripping detection sensor detects that the luggage is being gripped, the control unit increases the output of the actuator to an eighth output.

10. The grip detection sensors are provided on the left arm side and the right arm side of the user, The upper limb assist device according to claim 7 or 8, characterized in that when the grip detection sensors on both sides of the user's left arm and right arm detect that the luggage has been released from a gripped state, the control unit reduces the output of the actuator to the sixth output.

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