Assist device

Abstract

An assist device 10 comprises: an actuator 14 that causes an assist force to act on a user by applying a winding force according to a command value to a belt body 13; an inertial sensor 38 that detects an inclination angle of an upper body; a rotation angle sensor 36 that detects an operation position of the actuator 14; and a control unit 40 that finds the command value. The command value is a value obtained by adding a main assist command value and an additional assist force command value. The control unit 40 executes processing for finding the main assist command value on the basis of the inclination angle of the upper body, processing for finding an estimated motor rotation angle amount dφE on the basis of the inclination angle of the upper body, and processing for finding the additional assist force command value on the basis of a position difference Δφ between a detected motor rotation angle φD detected by the rotation angle sensor 36 and an estimated motor rotation angle φE based on the estimated motor rotation angle amount dφE.

Description

Assist Device

[0001] The present invention relates to an assist device.

[0002] For example, Patent Document 1 discloses an assisting device including a first attachment device worn on the upper body of a user, a second attachment device worn on the left and right legs of the user, a belt body provided along the back side of the user between the first and second attachment devices, and an actuator provided on the first attachment. This assisting device generates tension in the belt body by winding up a portion of the belt body with the actuator. This tension acts on the user as an assisting force that assists the rotation of the user's thighs.

[0003] Japanese Patent Application Laid-Open No. 2021-49601

[0004] In the assist device, the belt is wound up by the actuator and unwound from the actuator, thereby operating to follow changes in the user's posture.

[0005] However, the belt, which moves along the back of the user, may get caught or rub against the user's clothing. Such catching or friction may hinder the movement of the belt and reduce the belt's ability to follow changes in the user's posture. If the belt's ability to follow changes decreases, the timing at which the assist force is applied to the user may be off, or the belt may dig into the user's shoulders or back. This may result in a poor user experience.

[0006] An assisting device according to an embodiment includes a first attachment worn on a user's upper body, a second attachment worn on the user's left and right legs, a belt attached along the user's back between the first attachment and the second attachment, an actuator attached to the first attachment, capable of retracting and unretracting a portion of the belt, and applying a retracting force to the belt in accordance with a command value to exert an assisting force on the user, a first sensor detecting an inclination angle of the upper body, a second sensor detecting an operating position of the actuator, and a control unit calculating the command value. The command value is a value obtained by adding a first command value and a second command value. The control unit executes the following processes: calculating the first command value based on the inclination angle of the upper body; calculating an estimated value of a movement amount of the actuator based on the inclination angle of the upper body; and calculating the second command value based on a position difference between the movement position of the actuator detected by the second sensor and an estimated movement position of the actuator based on the estimated value of the movement amount.

[0007] According to the present disclosure, it is possible to suppress a decrease in the tracking ability of the belt body.

[0008] FIG. 1 is a rear view of an assisting device according to an embodiment. FIG. 2 is a rear view of the assisting device attached to the body of a user. FIG. 3 is a side view of the assisting device attached to the body of a user. FIG. 4 is a view showing the inside of a control box. FIG. 5 is a block diagram showing the control configuration of the assisting device. FIG. 6 is an explanatory diagram showing a case where a user wearing the assisting device changes their posture. FIG. 7 is a functional block diagram showing an example of a calculation process for a current command value in a control unit. FIG. 8 is a block diagram showing an example of a main assisting force calculation unit. FIG. 9 is a block diagram showing an example of an estimated rotation angle calculation unit. FIG. 10 is a block diagram showing an example of an additional assisting force calculation unit. FIG. 11A is a diagram showing the results of a verification test performed on the assisting device according to the embodiment, illustrating the relationship between the tilt angle and the motor current. FIG. 11B is a diagram showing the results of a verification test performed on the assisting device according to the embodiment, illustrating the relationship between the tilt angle and the motor rotation angle. FIG. 12 is a diagram showing the relationship between the tilt angle and the motor rotation angle when controlled using only the main assisting command value.

[0009] First, the contents of the embodiments will be listed and described. [Outline of the Embodiments] (1) An assisting device according to an embodiment includes a first attachment worn on the upper body of a user, a second attachment worn on the left and right legs of the user, a belt attached along the back of the user between the first attachment and the second attachment, an actuator attached to the first attachment, capable of retracting and unretracting a portion of the belt, and applying a retracting force to the belt according to a command value to exert an assisting force on the user, a first sensor detecting an inclination angle of the upper body, a second sensor detecting an operating position of the actuator, and a control unit calculating the command value. The command value is a value obtained by adding a first command value and a second command value. The control unit executes the following processes: calculating the first command value based on the inclination angle of the upper body; calculating an estimated value of the actuator's operating amount based on the inclination angle of the upper body; and calculating the second command value based on a position difference between the operating position of the actuator detected by the second sensor and an estimated operating position of the actuator based on the estimated value of the operating amount.

[0010] According to the above configuration, the second command value included in the command value is calculated based on a position difference between the operating position of the actuator detected by the second sensor and an estimated operating position of the actuator based on the tilt angle. The position difference is a value indicating whether the belt is following the user's posture. If the position difference becomes large, the control unit controls the second command value to be large and the operating amount difference to be small. This increases the winding force of the actuator to an extent that can eliminate snagging, friction, and the like that occurs between the user and the belt, and as a result, reduces the decrease in the tracking ability of the belt.

[0011] (2) In the above assist device, the process of calculating the estimated value of the movement amount preferably includes a process of retaining the maximum value of the tilt angle within a predetermined period, a process of calculating a tilt angle difference between the maximum value of the tilt angle and the current tilt angle, and a process of calculating the estimated value of the movement amount based on the tilt angle difference. In this case, the tilt angle difference indicates the angle difference between the upper body when tilted forward to the maximum extent and the current upper body. In other words, the tilt angle difference represents the angle of the upper body when the maximum value of the tilt angle is used as a reference. This makes it possible to appropriately set a reference for the tilt angle, which changes sequentially due to changes in the user's posture.

[0012] (3) In the assist device, the estimated operating position of the actuator is preferably an operating position that is moved by the estimated value of the operating amount from a maximum operating position of the actuator when the tilt angle is at a maximum value. In this case, the estimated operating position of the actuator is determined as an operating position based on the maximum operating position.

[0013] (4) In the assist device, the second command value may be calculated by proportional-plus-integral control based on the operation amount difference. In this case, the second command value can be calculated appropriately based on the operation amount difference.

[0014] (5) In the assist device, the actuator may include a pulley that winds up a portion of the belt body and a motor that drives the pulley, and the operating position may be a rotation angle of the motor.

[0015] [Details of the embodiment] A preferred embodiment will now be described with reference to the drawings. [Overall configuration of assist device 10] Fig. 1 is a rear view of the assist device according to the embodiment. Fig. 2 is a rear view of the assist device attached to the body of a user. Fig. 3 is a side view of the assist device attached to the body of a user.

[0016] In the assisting device 10 of the present disclosure, left and right refer to the left and right of a user wearing the assisting device 10 and standing upright, front and back refer to the front and back of the user, and up and down refer to the up and down of the user. Up is the user's head side, and down is the user's foot side.

[0017] The assist device 10 shown in FIG. 1 includes one first attachment 11 and two second attachments 12. The first attachment 11 is attached to the left and right shoulders BS, which are part of the user's (person's) body. The first attachment 11 may be attached to the user's upper body, such as the shoulders and chest, and may have a configuration other than that shown in the figure. The second attachments 12 are attached to the left and right legs BL, which are other parts of the user's body. In the present disclosure, the second attachments 12 are attached to the knees BN of the legs BL. The left and right second attachments 12 are symmetrical but have the same configuration. The second attachments 12 may also have a configuration other than that shown in the figure. The first attachment 11 and the two second attachments 12 are attached to two locations separated by the waist BW and hip joints, namely the shoulders BS and legs BL.

[0018] The first wearing device 11 has a base 21, a pair of shoulder belts 22, and a pair of armpit belts 23. The base 21 includes a control box 30 that houses a control device 15 (described later) and other components. The base 21 is worn on the user's back by the pair of shoulder belts 22 and the pair of armpit belts 23. The pair of shoulder belts 22 are provided on the upper part of the base 21 (control box 30). The distal ends 22a of the pair of shoulder belts 22 are connected to the pair of armpit belts 23. The pair of armpit belts 23 connect the distal ends 22a of the pair of shoulder belts 22 to the base 21 (control box 30). The length of the armpit belts 23 is adjustable. By adjusting the length of the armpit belts 23, the base 21 is fitted closely to the user's back (backside) BB. As a result, the first wearing device 11 is attached to the shoulders BS without being able to move in the front-to-back, left-to-right, or up-and-down directions. The first wearing device 11 may include, for example, a hard member as a portion to be hung on the shoulders BS. Although not shown, the first wearing device 11 may further include, as an accessory, a member (waist belt) to be worn on the waist BW of the user. The waist belt is connected to the base 21.

[0019] The second wearing device 12 is made of flexible fabric or the like. The second wearing device 12 has a knee main body 24 that is worn on the user's knees BN, and a pair of knee belts 25 extending from the knee main body 24. The pair of knee belts 25 are wrapped around the knees BN at upper and lower positions, respectively. The ends of the pair of knee belts 25 are fixed to the knee main body 24. The wrapping length of the knee belts 25 around the knees BN can be adjusted using a belt and buckle or a fastening member such as a hook-and-loop fastener. This ensures that the knee main body 24 is in close contact with the rear side of the knees BN. The second wearing device 12 is worn on the knees BN so that it cannot move in the front-to-back, left-to-right, or up-and-down directions.

[0020] The assist device 10 includes a first attachment 11 and left and right second attachments 12, as well as a belt body 13, an actuator 14, a control device 15, a battery 37, and an inertial sensor 38.

[0021] The belt body 13 is provided along the back side of the user. The belt body 13 connects the first wearing device 11 and the second wearing device 12. The belt body 13 has a first belt 16, a second belt 17, and a connecting member 18. The first belt 16 is provided on the upper body side of the user. The second belt 17 is provided on the lower body side of the user. The connecting member 18 connects the first belt 16 and the second belt 17. The first belt 16 and the second belt 17 are each long and flexible. As will be explained later, the connecting member 18 is composed of a rectangular ring-shaped body 27, such as a "flat ring" or "square ring," and a fastener 28, such as a buckle.

[0022] The first belt 16 and the second belt 17 are belt-like members made of cloth or leather and can be bent to fit the shape of the body. Note that the first belt 16 and the second belt 17 may also be string-like belts (wire-like members). The first belt 16 and the second belt 17 of the present disclosure are non-stretchable members. In other words, the first belt 16 and the second belt 17 have the property of being difficult to stretch or not stretching in the longitudinal direction.

[0023] The actuator 14, the control device 15, the battery 37, and the inertial sensor 38 are housed in a control box 30, which is a casing. Fig. 4 is a diagram showing the inside of the control box 30. The control box 30 has a back plate 31 and a cover 32 that covers the back plate 31. In Fig. 4, the cover 32 is shown by a virtual line (two-dot chain line). An opening (notch) 32a is provided at the lower end of the cover 32. The first belt 16 passes through the opening 32a.

[0024] The actuator 14 is capable of winding up a portion of the belt 13 and unwinding a portion of the belt 13. In other words, the actuator 14 expands and contracts the belt 13 between the first wearing device 11 and the second wearing device 12. The actuator 14 applies a winding force to the belt 13, thereby exerting an assist force on the user. The actuator 14 has a motor 33, a reducer unit 34, and a drive pulley 35. The motor 33 is a brushless DC motor. The motor 33 has a rotating shaft 33a. The rotating shaft 33a rotates at a predetermined torque and a predetermined rotation speed based on a current command value determined by the control device 15.

[0025] The motor rotation angle (operating position), which is the rotation angle of the rotating shaft 33a of the motor 33, is detected by a rotation angle sensor 36. The rotation angle sensor 36 is provided on the motor 33. The rotation angle sensor 36 of the present disclosure is a Hall sensor used for rotation control of the motor 33. The rotation angle sensor 36 may be a rotary encoder or a resolver. The output of the rotation angle sensor 36 is provided to the control device 15.

[0026] The reducer unit 34 is composed of a plurality of gears. The reducer unit 34 reduces the rotation speed of the motor 33 to rotate an output shaft 34a of the reducer unit 34. A drive pulley 35 is connected to the output shaft 34a so as to be rotatable integrally therewith. One end 16a of the first belt 16 is fixed to the drive pulley 35. When the drive pulley 35 rotates in one direction due to the forward rotation of the motor 33, the first belt 16 is wound around the drive pulley 35. When the drive pulley 35 rotates in the other direction due to the reverse rotation of the motor 33, the first belt 16 is unwound from the drive pulley 35. In this way, the actuator 14 can perform winding and unwinding operations of the first belt 16, which is part of the belt body 13.

[0027] The control device 15 includes, for example, a computer and a drive circuit for the motor 33. The control device 15 has a function of controlling the actuator 14 based on the output of the rotation angle sensor 36 and the output of the inertial sensor 38. The processing performed by the control device 15 will be described later.

[0028] The inertial sensor 38 includes, for example, at least a three-axis acceleration sensor. The output of the inertial sensor 38 is provided to the control device 15. The inertial sensor 38 may include an angular velocity sensor or a gyro sensor in addition to the acceleration sensor. The inertial sensor 38 can output information indicating the attitude of the control box 30. The inertial sensor 38 may be provided outside the control box 30. The battery 37 supplies power to the control device 15, the motor 33, and each part of the assist device.

[0029] [Regarding the Belt 13] As described above, the belt 13 includes the first belt 16, the second belt 17, and the connecting member 18. One end 16a of the first belt 16 is wound around and fixed to the drive pulley 35. The other end 16b of the first belt 16 is fixed to the connecting member 18. When the first belt 16 is wound around the drive pulley 35, the connecting member 18 is pulled up. When the connecting member 18 is forcibly pulled down, the first belt 16 is let out (pulled out) from the drive pulley 35. There is a correlation between the amount of winding or letting out (pulling out) of the first belt 16 around the drive pulley 35 and the rotation amount of the output shaft of the motor 33. Therefore, the amount of winding or letting out of the first belt 16 can be obtained based on parameters related to the rotation of the motor 33.

[0030] As shown in Figure 4, the connecting member 18 includes a ring-shaped body 27 and a fastener (buckle) 28. The fastener 28 has a first member 28a and a second member 28b. The first member 28a and the second member 28b can be separated and connected. The first member 28a is attached to the other end 16b of the first belt 16. The second member 28b and the ring-shaped body 27 are connected by a short belt 29. The second belt 17 is inserted through the ring-shaped body 27.

[0031] The second belt 17 is folded back at the annular body 27 and hung on the annular body 27. The annular body 27 supports the folded second belt 17. As a result, the second belt 17 is supported by the annular body 27 without being fixed to the annular body 27. Therefore, the second belt 17 is movable in both directions along its longitudinal direction (the directions of arrows X in FIG. 4 ).

[0032] 1 and 2, the second belt 17 is attached to the second wearing device 12. Specifically, the second belt 17 has a belt shape. One end 17a of the second belt 17 is attached to the left second wearing device 12. The other end 17d of the second belt 17 is attached to the right second wearing device 12. An intermediate portion 17c of the second belt 17 is hung on a connecting member 18.

[0033] In addition to the intermediate portion 17c, the second belt 17 includes a left leg belt portion 19 that extends from the connecting member 18 (intermediate portion 17c) to the second wearing device 12 on the left side, and a right leg belt portion 20 that extends from the connecting member 18 (intermediate portion 17c) to the second wearing device 12 on the right side. As described above, the second belt 17 is not fixed to the annular body 27, so the lengths of the left leg belt portion 19 and the right leg belt portion 20 can be freely changed. However, the total length of the left leg belt portion 19 and the right leg belt portion 20 is constant. With this configuration, the second belt 17 does not restrict the user's walking, allowing the user to walk comfortably.

[0034] The second belt 17 further includes a connecting member 39. The connecting member 39 connects the left leg belt portion 19 and the right leg belt portion 20. The connecting member 39 prevents the lateral gap between the left leg belt portion 19 and the right leg belt portion 20 from widening when the user changes their posture. In other words, the connecting member 39 prevents the left leg belt portion 19 and the right leg belt portion 20 from misaligning with the back side of the user's leg BL.

[0035] [Regarding Control of Assisting Force by Control Device 15] Fig. 5 is a block diagram showing the control configuration of the assist device 10. As shown in Fig. 5, a rotation angle sensor 36 and an inertia sensor 38 are connected to the control device 15. The control device 15 controls these and acquires outputs from the rotation angle sensor 36 and the inertia sensor 38. The control device 15 includes a control unit 40 formed of a computer or the like, and a drive circuit (motor driver) 42. The drive circuit 42 controls the operation of the motor 33 based on a current command value provided by the control unit 40.

[0036] The control unit 40 includes a processing unit 40a including a CPU (Central Processing Unit) and a storage unit 40b including a memory and a hard disk. The processing unit 40a executes various processes based on various programs and parameters stored in the storage unit 40b. The processing unit 40a controls the actuator 14 using a current command value. The processing unit 40a has a function of executing a calculation process 40a1 that calculates the current command value. The processing unit 40a provides the current command value to a drive circuit 42. The current command value is a command for controlling the motor 33 (actuator 14). The current command value indicates the current value to be supplied to the actuator 14. The current command value is calculated based on the output of the rotation angle sensor 36 and the output of the inertia sensor 38. The processing unit 40a provides the current command value to the drive circuit 42. The drive circuit 42 supplies power to the motor 33 in accordance with the current command value, thereby operating the motor 33. As a result, the actuator 14 generates an assist force corresponding to the user's posture. As a result, the processing unit 40a controls the assist force according to the user's posture.

[0037] The control of the assist force performed by the processing unit 40a (control unit 40) will be described below. The control unit 40 determines the inclination angle of the upper body based on the output of the inertial sensor 38. The inclination angle of the upper body is the angle of the user's upper body relative to a reference position of the upper body. The inertial sensor 38 is provided on the user's upper body. Therefore, the control unit 40 can determine the inclination angle of the upper body based on the output of the inertial sensor 38. In other words, the inertial sensor 38 constitutes a first sensor that detects the inclination angle of the user's upper body.

[0038] Furthermore, the control unit 40 determines the operating position of the actuator 14 (motor 33) based on the output of the rotation angle sensor 36. The control unit 40 determines the motor rotation angle as the operating position of the actuator 14. In other words, the rotation angle sensor 36 constitutes a second sensor that detects the operating position of the actuator 14. In the following description, the motor rotation angle obtained based on the output of the rotation angle sensor 36 is also referred to as the detected motor rotation angle.

[0039] When the user is in an upright position, the control unit 40 controls the actuator 14 so that no winding force is applied to the belt 13. Therefore, in this case, no assist force acts on the user. Note that when the user is in an upright position, the actuator 14 may be controlled so that an extremely weak winding force is applied to the belt 13. This makes it possible to prevent the belt 13 from loosening more than necessary when the user is in an upright position.

[0040] 6 is an explanatory diagram illustrating a case where a user wearing the assist device 10 changes posture. Fig. 6 shows a user in an upright posture and a user in a forward-leaning posture. The upright posture refers to a posture in which the user's upper body and thighs are substantially aligned vertically. The forward-leaning posture refers to a posture in which the user's upper body is leaning forward with the user's knees BN barely bent.

[0041] Here, we will explain the case in which the user in Figure 6 changes posture between an upright posture and a forward-leaning posture. First, when a user in an upright posture starts to change posture toward a forward-leaning posture, the belt 13 is pulled from the drive pulley 35 by the tension of the belt 13 caused by the posture change. In other words, the belt 13 is forcibly fed by the actuator 14. As shown in Figure 6, assume that the inclination angle θ changes from 0° to θ1 and the forward-leaning posture is maintained at the inclination angle θ of θ1. The inclination angle θ shown in Figure 6 is the angle of the user's upper body UB relative to the state in which the user's upper body UB is aligned with the vertical line VL. When the inclination angle θ is close to 0°, the user's posture is upright. When the inclination angle θ is significantly different from 0°, the user's posture is a forward-leaning posture. Note that in this embodiment, the inclination angle θ is also the waist bending angle between the upper body and the thighs.

[0042] While the user is in a forward-leaning position, the actuator 14 applies a winding force to the belt body 13 in accordance with the inclination angle θ. In the forward-leaning position shown in FIG. 6 , when the actuator 14 (its motor 33) applies a winding force to the first belt 16, the connecting member 18 pulls the second belt 17 toward the actuator 14, i.e., upward. The second belt 17 has both ends 17a, 17d attached to the left and right second wearing devices 12. The second wearing devices 12 are fixed to the knees BN. Therefore, when a winding force is applied to the first belt 16, tension acts on the first belt 16 and the second belt 17. This tension acts as an assist force (auxiliary force) for the user.

[0043] This tension generates a rearward acting force F1 in the first wearing device 11. That is, the acting force F1 is generated in a direction that raises the upper body of the user who is in a forward-leaning position. At the same time, the tension generates an acting force F2 in the second belt 17 that pushes the left and right buttocks of the user forward. That is, the actuator 14 generates an assist force that assists the rotation of the thighs between the first wearing device 11 and the second wearing device 12. This makes it easier for the user to maintain a forward-leaning position and to return from a forward-leaning position to an upright position, reducing the muscle load on the user's back muscles, quadriceps, etc., and assisting the user's movements.

[0044] When the user is in a forward-leaning position, the actuator 14 always applies a winding force to the belt 13. Therefore, tension is always applied to the belt 13. Therefore, when a user in a forward-leaning position starts to change their position toward an upright position, the belt 13 is wound around the actuator 14 by the winding force of the actuator 14. Therefore, the belt 13 operates to follow the change in the user's position.

[0045] Because the belt 13 operates to follow changes in the user's posture, there is a correlation, in principle, between the amount of the belt 13 wound and fed by the drive pulley 35 and the tilt angle θ of the user's upper body. Furthermore, it can be said that the motor rotation angle of the motor 33 increases according to the amount of the belt 13 fed out when the belt 13 is fed out, and decreases according to the amount of the belt 13 wound up when the belt 13 is wound up. Therefore, there is also a correlation between the motor rotation angle of the motor 33 and the tilt angle θ.

[0046] As described above, the motor rotation angle of the motor 33 is the amount of movement of the actuator 14. In other words, there is a correlation between the amount of movement of the actuator 14 and the tilt angle θ. Therefore, the control unit 40 can estimate the motor rotation angle (the movement position of the actuator 14) based on the tilt angle θ. This point will be described in detail later.

[0047] As described above, the control unit 40 determines a current command value using the output of the rotation angle sensor 36 and the output of the inertia sensor 38, and provides the current command value to the drive circuit 42. In this way, the control unit 40 controls the actuator 14. The actuator 14 operates based on the operation control of the drive circuit 42 to which the current command value is provided, and applies a winding force to the belt body 13 according to the current command value, thereby exerting an assist force on the user.

[0048] [Regarding the Calculation Process of the Current Command Value] FIG. 7 is a functional block diagram showing an example of the calculation process of the current command value possessed by the control unit 40. In calculation process 40a1, the control unit 40 performs calculation using the user's tilt angle θ and the detected motor rotation angle φD. As described above, the detected motor rotation angle φD is the motor rotation angle of the motor 33 (the operating position of the actuator 14) detected by the rotation angle sensor 36. The user's tilt angle θ and the detected motor rotation angle φD are calculated by the control unit 40 as time-series discrete value data while the assist device 10 is operating. The tilt angle θ is provided to the main assist force calculation unit 50. The main assist force calculation unit 50 calculates the main assist force command value from the tilt angle θ. Note that in FIG. 7, the control unit 40 calculates the tilt angle θ and the detected motor rotation angle φD as relative values.

[0049] FIG. 8 is a block diagram showing an example of the main assist force calculation unit 50. The tilt angle θ provided to the main assist force calculation unit 50 is provided to a multiplier 50a and a differentiator 50b. The multiplier 50a multiplies the tilt angle θ by a proportional gain Kp1. The output of the multiplier 50a is provided to a downstream adder 50c. The differentiator 50b differentiates the tilt angle θ to output an angular velocity ω1. The angular velocity ω1 is provided to a multiplier 50d. The multiplier 50d multiplies the angular velocity ω1 by a proportional gain Kp2. The output of the multiplier 50d is provided to the adder 50c. The adder 50c adds the output of the multiplier 50a and the output of the multiplier 50d. The output of the adder 50c is output as a main assist command value. In this way, the main assist force calculation unit 50 calculates the main assist command value through proportional control based on the tilt angle θ and the angular velocity ω1 of the user's upper body. The proportional gains Kp1 and Kp2 are adjusted as appropriate.

[0050] As shown in Fig. 7, the main assist command value is provided to an adder 52. The tilt angle θ is also provided to an estimated rotation angle calculation unit 54. The estimated rotation angle calculation unit 54 calculates an estimated motor rotation angle dφE based on the tilt angle θ. The estimated motor rotation angle dφE is a value obtained by expressing, in terms of motor rotation angle, an estimated value of the operation amount of the motor 33 (actuator 14) estimated from the tilt angle θ.

[0051] FIG. 9 is a block diagram showing an example of the estimated rotation angle calculation unit 54. The tilt angle θ provided to the estimated rotation angle calculation unit 54 is provided to a maximum value holding unit 54a and an adder 54b. The maximum value holding unit 54a outputs a maximum value θmax. The maximum value θmax is the maximum value of the tilt angle θ within an operation period (a predetermined period). The operation period is the period during which the power of the assist device 10 remains ON after it is switched ON. The maximum value holding unit 54a has a function of holding the maximum value θmax and a function of comparing the held maximum value θmax with the most recently provided tilt angle θ and updating the larger tilt angle θ to the maximum value θmax. The maximum value θmax output by the maximum value holding unit 54a is provided to the adder 54b. The adder 54b subtracts the tilt angle θ from the maximum value θmax to obtain a tilt angle difference Δθ. The tilt angle difference Δθ is provided to the calculation unit 54c.

[0052] The calculation unit 54c calculates the estimated motor rotation angle dφE based on the tilt angle difference Δθ. As described above, there is a correlation between the amount of operation of the actuator 14 and the tilt angle θ. The calculation unit 54c has data indicating the correlation between the amount of change in the tilt angle θ and the amount of change in the detected motor rotation angle φD. Based on this data, the calculation unit 54c converts the tilt angle difference Δθ into a value equivalent to the amount of change in the detected motor rotation angle φD to calculate the estimated motor rotation angle dφE. Note that this data may be any data that allows for calculating a value equivalent to the amount of change in the detected motor rotation angle φD from the tilt angle difference Δθ, and may be a table calculated by experiment, simulation, or the like, or may be a mathematical formula.

[0053] Here, the tilt angle difference Δθ represents the tilt angle of the upper body when the maximum value θmax is used as a reference. Therefore, the output of the calculation unit 54c (estimated motor rotation angle dφE) is also calculated as a movement amount when the maximum value θmax is used as a reference. The maximum value θmax can be said to be the value when the user tilts the upper body forward to the maximum extent. Therefore, the tilt angle difference Δθ is the angle difference between the upper body when tilted forward to the maximum extent and the current state of the upper body. Therefore, the estimated motor rotation angle dφE represents the angle difference between the motor rotation angle when the upper body is tilted forward to the maximum extent and the estimated value of the current motor rotation angle.

[0054] In this embodiment, the tilt angle difference Δθ represents an angle when the maximum value θmax is used as a reference, which allows an appropriate reference to be set for the tilt angle θ, which is a relative value and changes successively depending on changes in the user's posture.

[0055] As described above, the estimated rotation angle calculation unit 54 calculates the estimated motor rotation angle dφE based on the tilt angle θ. As shown in Fig. 7 , the estimated motor rotation angle dφE is provided to the additional assist force calculation unit 56. The detected motor rotation angle φD is also provided to the additional assist force calculation unit 56. The additional assist force calculation unit 56 calculates an additional assist force command value based on the estimated motor rotation angle dφE and the detected motor rotation angle φD.

[0056] 10 is a block diagram showing an example of the additional assist force calculation unit 56. The additional assist force calculation unit 56 includes a maximum value holding unit 56a, an adder 56b, a differentiator 56c, a first PI control unit 57, and a second PI control unit 58.

[0057] The detected motor rotation angle φD is provided to a maximum value holding unit 56a, a first PI control unit 57, and a differentiator 56c. The maximum value holding unit 56a outputs a maximum value φDmax. The maximum value φDmax is the maximum value (maximum angular position) of the detected motor rotation angle φD within an operating period (within a predetermined period). The maximum value holding unit 56a has a function of holding the maximum value φDmax and a function of comparing the held maximum value φDmax with the most recently provided detected motor rotation angle φD and updating the maximum value φDmax to the larger value. In other words, the maximum value holding unit 56a holds the maximum value φDmax (maximum operating position) of the detected motor rotation angle φD when the tilt angle θ is at its maximum value θmax.

[0058] The maximum value φDmax output by the maximum value holding unit 56a is provided to the adder 56b. In addition to the maximum value φDmax, the adder 56b is also provided with an estimated motor rotation angle dφE. The adder 56b subtracts the estimated motor rotation angle dφE from the maximum value φDmax to obtain the estimated motor rotation angle φE (the estimated operating position of the actuator 14).

[0059] As described above, the estimated motor rotation angle dφE indicates the angular difference between the motor rotation angle when the upper body is tilted forward to the maximum extent and the estimated value of the current motor rotation angle. Therefore, subtracting the estimated motor rotation angle dφE from the maximum value φDmax obtains a position (motor rotation angle) moved from the maximum value φDmax by the estimated motor rotation angle dφE. In other words, the estimated motor rotation angle φE (estimated operating position of the actuator 14) is the motor rotation angle (operating position) moved from the maximum value φDmax (maximum operating position) by the estimated motor rotation angle dφE (estimated value of the operating amount). In this way, in this embodiment, the estimated motor rotation angle φE is obtained as an operating position based on the maximum value φDmax.

[0060] The estimated motor rotation angle φE is provided to the first PI control unit 57. In addition to the estimated motor rotation angle φE, the first PI control unit 57 is also provided with the detected motor rotation angle φD as described above.

[0061] The first PI control unit 57 includes adders 57a and 57b, multipliers 57c and 57d, and an integrator 57e. The estimated motor rotation angle φE and the detected motor rotation angle φD are provided to the adder 57a. The adder 57a subtracts the detected motor rotation angle φD from the estimated motor rotation angle φE. As described above, the estimated motor rotation angle φE is the motor rotation angle shifted from the maximum value φDmax by the estimated motor rotation angle amount dφE (estimated value of the operating amount). Therefore, the output of the adder 57a indicates the motor rotation angle difference Δφ (position difference) between the motor rotation angle detected by the rotation angle sensor 36 (operating position of the actuator 14) and the estimated value of the motor rotation angle (estimated operating position of the actuator 14).

[0062] The output of the adder 57a is provided to multipliers 57c and 57d. The multiplier 57c multiplies the output of the adder 57a by a proportional gain Kp3. The output of the multiplier 57c is provided to the adder 57b. The multiplier 57d multiplies the output of the adder 57a by an integral gain Ki1. The output of the multiplier 57d is provided to the integrator 57e. The output of the integrator 57e is provided to the adder 57b. The adder 57b adds the output of the multiplier 57c and the output of the integrator 57e. The output of the adder 57b is provided to the second PI control unit 58. The output of the adder 57b is the output of the first PI control unit 57. The proportional gain Kp3 and the integral gain Ki1 are adjusted as appropriate.

[0063] In addition to the output of the first PI control unit 57, the second PI control unit 58 is also supplied with the angular velocity ω2. The angular velocity ω2 is an angular velocity obtained by differentiating the detected motor rotation angle φD. As described above, the detected motor rotation angle φD is supplied to the differentiator 56c. The differentiator 56c differentiates the detected motor rotation angle φD and supplies the angular velocity ω2 to the second PI control unit 58.

[0064] The second PI control unit 58 includes adders 58a and 58b, multipliers 58c and 58d, and an integrator 58e. The output of the first PI control unit 57 and the angular velocity ω2 are provided to the adder 58a. The adder 58a subtracts the angular velocity ω2 from the output of the first PI control unit 57. The output of the adder 58a is provided to multipliers 58c and 58d. The multiplier 58c multiplies the output of the adder 58a by a proportional gain Kp4. The output of the multiplier 58c is provided to the adder 58b. The multiplier 58d multiplies the output of the adder 58a by an integral gain Ki2. The output of the multiplier 58d is provided to the integrator 58e. The output of the integrator 58e is provided to the adder 58b. The adder 58b adds the output of the multiplier 58c and the output of the integrator 58e, and outputs an additional assist force command value. In this way, the first PI control unit 57 and the second PI control unit 58 perform proportional-plus-integral control based on the motor rotational angle difference Δφ and the detected motor rotational angle φD to determine the additional assist force command value. Note that the proportional gain Kp4 and the integral gain Ki2 are adjusted as appropriate.

[0065] 7, the additional assist force command value is provided to an adder 52. The adder 52 adds the main assist command value (first command value) and the additional assist force command value (second command value) to obtain a current command value. The current command value obtained by the calculation process 40a1 is provided to a drive circuit 42 and used to control the actuator 14 (motor 33).

[0066] According to the above configuration, the additional assist force command value included in the current command value is calculated based on the motor rotation angle difference Δφ (position difference) between the detected motor rotation angle φD (operating position of the actuator 14) detected by the rotation angle sensor 36 (second sensor) and the estimated motor rotation angle φE (estimated operating position of the actuator 14) based on the tilt angle θ. The motor rotation angle difference Δφ is a value indicating whether the belt 13 is following the user's posture. When the motor rotation angle difference Δφ increases, the control unit 40 of the present embodiment increases the additional assist force command value and controls the motor rotation angle difference Δφ to decrease. This increases the winding force of the actuator to a level that can eliminate snagging, friction, and the like that occurs between the user and the belt. As a result, the deviation between the tilt angle θ and the detected motor rotation angle φD can be suppressed, and the decrease in the tracking ability of the belt 13 can be suppressed.

[0067] [Verification Test] Figures 11A and 11B are diagrams showing the results of a verification test conducted on the assist device 10 according to the above embodiment. Figure 11A is a diagram showing the relationship between the tilt angle and the motor current of the motor 33. In Figure 11A, the horizontal axis represents time, and the vertical axis represents the tilt angle and the motor current. Note that the tilt angle in Figure 11A is an angle with 0° being the angle when the user's upper body is in a vertical position.

[0068] In Figure 11A, line L1 shows the change in the tilt angle over time. Line L1 shows the tilt angle decreasing from approximately 90° over time. In other words, Figure 11A shows the process of the user's upper body changing from a nearly horizontal position to an upright position.

[0069] In Fig. 11A, line L2 indicates the value of the current flowing through the motor 33. Line L21 indicates the value of the current flowing through the motor 33 when controlled only by the primary assist command value. Line L21 gradually decreases over time as the tilt angle decreases. In Fig. 11A, the difference between line L2 and line L21 is the current added by the additional assist force command value. Note that the current value added by the additional assist force command value is approximately 20% of the current value based on only the primary assist command value.

[0070] In this way, when the user's posture changes from a forward-leaning posture to an upright posture, the control unit 40 controls the additional assist force command value to be larger, and temporarily increases the overall current value flowing to the motor 33.

[0071] 11B is a diagram showing the relationship between the tilt angle and the motor rotation angle of the motor 33. In FIG. 11B, the horizontal axis represents time, and the vertical axis represents the tilt angle and the motor rotation angle. Note that the time and tilt angle in FIG. 11B correspond to the time and tilt angle in FIG. 11A. Line L3 in FIG. 11B shows the change in the tilt angle over time. Therefore, line L1 in FIG. 11A and line L3 in FIG. 11B are the same line.

[0072] 11B, line L4 shows the change over time in the motor rotation angle of the motor 33. Comparing line L3 and line L4, there is no significant difference between the change over time in the tilt angle and the change over time in the motor rotation angle.

[0073] FIG. 12 is a diagram showing the relationship between the tilt angle and the motor rotation angle of the motor 33 when controlled only by the primary assist command value. In FIG. 12, line L5 shows the change in the tilt angle over time. Line L6 shows the change in the motor rotation angle of the motor 33 over time. As shown in FIG. 12, when controlled only by the primary assist command value, a discrepancy occurs between the tilt angle and the motor rotation angle. This indicates that when the user changes posture from a forward-leaning posture to an upright posture, the belt member 13 does not follow the posture change. In contrast, in this embodiment, as shown in FIG. 11B, there is no significant difference between the change in the tilt angle over time and the change in the motor rotation angle over time, indicating that the belt member 13 follows the posture change.

[0074] From these results, it can be seen that according to this embodiment, when the user's posture changes, the control unit 40 increases the additional assist force command value to increase the winding force of the actuator 14, thereby suppressing a decrease in the tracking ability of the belt body 13.

[0075] [Others] The embodiments disclosed herein are illustrative in all respects and are not limiting. For example, in the above embodiment, the operating position of the actuator 14 is the motor rotation angle of the motor 33. However, the operating position of the actuator 14 may be, for example, the position of the belt 13 relative to a reference position provided on the control box 30 or the like. In this case, a sensor that detects the position of the belt 13 is used instead of the rotation angle sensor 36.

[0076] Furthermore, while the above embodiment has mainly described the case where the user's posture changes from a leaning forward posture to an upright posture, the same effect can be achieved when changing from an upright posture to a leaning forward posture. For example, increasing the motor current when changing from an upright posture to a leaning forward posture may hinder the user's movement. Therefore, the motor current is increased according to the state of the user's movement. More specifically, the speed of the user's movement (tilt angle) is detected, and when the speed of the user's movement approaches zero and it is determined that the user is likely to stop moving (maintain the posture), the motor current is increased. In this way, the user's movement is detected, and the motor current value is increased or decreased so as not to hinder the movement. This increase or decrease provides an assist force with good tracking.

[0077] The scope of the present invention is not limited to the above-described embodiments, but includes all modifications within the scope of equivalents to the configurations described in the claims.

[0078] REFERENCE SIGNS LIST 10 Assist device 11 First attachment 12 Second attachment 13 Belt body 14 Actuator 33 Motor 35 Drive pulley 36 Rotation angle sensor (second sensor) 38 Inertia sensor (first sensor) 40 Control unit BL Leg UB Upper body

Claims

1. A first device worn on the user's upper body, A second attachment device is attached to the left and right legs of the user, A belt body is provided along the user's back, spanning the first and second attachments, An actuator is provided on the first mounting device, which is capable of winding up and unwinding a portion of the belt body, and applies an assisting force to the user by applying a winding force to the belt body according to a command value, A first sensor for detecting the tilt angle of the upper body, A second sensor for detecting the operating position of the actuator, A control unit for determining the command value, Equipped with, The aforementioned command value is the sum of the first command value and the second command value. The control unit, A process to determine the first command value based on the tilt angle of the upper body, A process to obtain an estimated value of the actuator's operating amount based on the tilt angle of the upper body, The process of determining the second command value is performed based on the position difference between the operating position of the actuator detected by the second sensor and the estimated operating position of the actuator based on the estimated value of the amount of motion. Assist device.

2. The process for obtaining an estimated value of the aforementioned amount of motion is as follows: A process for retaining the maximum value of the inclination angle within a predetermined period, A process to determine the difference in inclination angle between the maximum value of the aforementioned inclination angle and the current aforementioned inclination angle, The process includes obtaining an estimated value of the amount of motion based on the difference in the tilt angle. The assist device according to claim 1.

3. The estimated operating position of the actuator is the operating position obtained by moving from the maximum operating position of the actuator, where the tilt angle is at its maximum value, by the estimated amount of movement. The assist device according to claim 2.

4. The second command value is determined by proportional-integral control based on the position difference. The assist device according to claim 1.

5. The actuator is A pulley that winds up a portion of the aforementioned belt body, The system comprises a motor that drives the pulley, The aforementioned operating position is the rotation angle of the motor. The assist device according to any one of claims 1 to 4.