JP2018135974A - Torque transmission device and operation auxiliary device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque transmission device capable of detecting an extension length of a flexible cable of the torque transmission device, and an operation auxiliary device.SOLUTION: A torque transmission device comprises: a flexible cable being wound around a driven-pulley at an intermediate part, and fixed to first and second driving pulleys on both ends, respectively; an acquisition part for acquiring first position information relating to a reference position of the flexible cable introduced near the first driving pulley than the driven-pulley, and second position information relating to a reference position of the flexible cable introduced nearer the second driving pulley side than the driven pulley; and an elongation detection part for detecting elongation of the flexible cables based on the first and second position information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a torque transmission device using a pulley and a flexible cable, and an operation assisting device including such a torque transmission device.

  2. Description of the Related Art Human body-mounted robots are known as operation assistance devices that support or assist the movement of healthy or disabled people. The human body-mounted robot, for example, controls a joint unit worn by a user, a sensor for detecting a user's intention or operation state, a drive unit that generates torque to be applied to the joint unit, and driving of the drive unit. And a control device. In general, the drive unit includes an electric motor and a speed reducer that converts high-speed rotation of the motor into low-speed rotation suitable for human body operation. The transmission transmits the rotation of the motor to the joint at a gear ratio of 1/50 to 1/200, for example. The drive unit is composed of, for example, a harmonic drive (registered trademark) or a combination of a worm gear and a DC motor. As such a human wearable robot, there is a robot using a torque transmission device including a plurality of pulleys and a flexible cable. The torque transmission device including the pulley and the flexible cable has an advantage that the degree of freedom of arrangement of the drive unit can be increased.

JP 2008-232360 A

  Here, in a torque transmission device including a pulley and a flexible cable, if the flexible cable is slack or stretched (hereinafter, slack or stretch is also referred to as “elongation”), the torque transmission characteristics are shifted. When the elongation becomes large, there is a problem that the flexible cable is broken. For this reason, it is considered useful if the extension of the flexible cable can be detected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a torque transmission device and an operation assisting device capable of detecting the extension of the flexible cable of the torque transmission device. is there.

  According to an aspect of the present invention, a flexible cable in which an intermediate portion is wound around a driven pulley and both ends are fixed to a first driving pulley and a second driving pulley, respectively, and the first driving than the driven pulley is provided. First position information related to the reference position of the flexible cable derived to the pulley side, and second information related to the reference position of the flexible cable derived to the second drive pulley side than the driven pulley. There is provided a torque transmission device comprising: an acquisition unit that acquires the position information of the first position information; and an extension detection unit that detects extension of the flexible cable based on the first position information and the second position information.

  According to another aspect of the present invention, the first flexible cable having both ends fixed to the first drive pulley and the driven pulley, and the both ends fixed to the second drive pulley and the driven pulley, respectively. The second flexible cable, the first position information related to the reference position of the first flexible cable, and the second position information related to the reference position of the second flexible cable. An acquisition unit for acquiring, an extension detection unit for detecting extension of at least one of the first flexible cable and the second flexible cable based on the first position information and the second position information; A torque transmission device is provided.

  According to another aspect of the present invention, any one of the torque transmission devices described above, and a first arm member and a second arm member that are connected so as to be capable of relative motion and perform relative motion by the torque transmission device; A motion assisting device is provided.

  As described above, according to the present invention, the extension of the flexible cable of the torque transmission device can be detected.

It is a schematic diagram which shows the structural example of the torque transmission apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows an example of a cable expansion | extension characteristic database. It is a schematic diagram which shows the structural example of the torque transmission apparatus which concerns on the modification of the embodiment. It is explanatory drawing which shows the operation assistance apparatus to which the torque transmission apparatus which concerns on the same embodiment is applied.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Example of overall configuration of torque transmission device>
A torque transmission device 10 according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating a configuration example of the torque transmission device 10. The torque transmission device 10 includes a flexible cable 9, a first drive pulley 3, a second drive pulley 5, a driven pulley 1, a first actuator 11, a second actuator 21, Rotation sensor 13, second rotation sensor 23, and control device 30.

  Both ends of the flexible cable 9 are fixed to the first drive pulley 3 and the second drive pulley 5, respectively, and an intermediate portion of the flexible cable 9 is wound around the driven pulley 1. Specifically, a portion 9 a on one end side of the flexible cable 9 led out from the driven pulley 1 is fixed to the first drive pulley 3, and the portion on the other end side of the flexible cable 9 led out from the driven pulley 1. The portion 9 b is fixed to the second drive pulley 5. The flexible cable 9 may be fixed by being wound around the first drive pulley 3 and the second drive pulley 5 a plurality of times.

  As the flexible cable 9, for example, a cable made of steel or synthetic fiber is used. Among these, synthetic fiber cables are more suitable as cables applied to devices that require downsizing because they are superior in durability when wound around pulleys with relatively small diameters compared to steel cables. It is.

  In the above description, the flexible cable 9 is a single cable connected from the end portion 9a to the other end portion 9b. However, the flexible cable 9 is divided into two. Also good. For example, the torque transmission device 10 includes a first flexible cable 9a having both ends fixed to the first drive pulley 3 and the driven pulley 1, respectively, and both ends having a second drive pulley 5 and a driven pulley 1, respectively. And a second flexible cable 9b fixed to the cable. In this case, the flexible cables 9 a and 9 b may be fixed by being wound around the first driving pulley 3, the second driving pulley 5 and the driven pulley 1 a plurality of times.

  The first actuator 11 rotationally drives the first drive pulley 3. The second actuator 21 rotationally drives the second drive pulley 5. The driving of the first actuator 11 and the second actuator 21 is controlled by the drive control unit 37 of the control device 30. As the first actuator 11 and the second actuator 21, an electrically driven rotary motor is typically used. In this case, the first drive pulley 3 is coaxially fixed to the output shaft 11 a of the first actuator 11, and the second drive pulley 5 is coaxial to the output shaft 21 a of the second actuator 21. It is fixed.

  The first actuator 11 and the second actuator 21 may include a reduction mechanism (not shown). Further, the first actuator 11 and the second actuator 21 may be an actuator that combines an electrically driven linear motor and a torque conversion mechanism that converts a linear motion of the linear motor into a rotational motion.

  The first rotation sensor 13 detects the rotation angle θ1 of the first drive pulley 3. The second rotation sensor 23 detects the rotation angle θ2 of the second drive pulley 5. For example, a rotary encoder is used as the first rotation sensor 13 and the second rotation sensor 23, but other rotation sensors may be used. The information of the rotation angle θ1 detected by the first rotation sensor 13 is one aspect of the first position information related to the reference position of the portion 9a on the one end side of the flexible cable 9. The information on the rotation angle θ2 detected by the second rotation sensor 23 is an aspect of second position information related to the reference position of the portion 9b on the other end side of the flexible cable 9.

  The first position information and the second position information are information related to the position of the reference position that is appropriately set in the portion 9a on one end side and the portion 9b on the other end side of the flexible cable 9, respectively. The reference position of the portion 9a on one end side of the flexible cable 9 may be, for example, a fixed position of the tip of the portion 9a on one end side of the flexible cable 9 with respect to the first drive pulley 3. Further, the reference position of the portion 9 b on the other end side of the flexible cable 9 may be, for example, a fixed position of the tip of the portion 9 b on the other end side of the flexible cable 9 with respect to the second drive pulley 5. However, the reference position of each portion 9a, 9b of the flexible cable 9 may be a position other than the fixed position of the tip as long as it is an invariable position set as appropriate.

  In the torque transmission device 10, the first drive pulley 3 and the second drive pulley 5 are rotated by driving at least one of the first actuator 11 and the second actuator 21, so that the flexible cable 9 is connected. Rotational torque is transmitted to the driven pulley 1 via this. Thereby, the driven pulley 1 can output rotational torque.

  The control device 30 controls driving of the first actuator 11 and the second actuator 21. Further, in the torque transmission device 10 according to the present embodiment, the control device 30 detects the extension of the flexible cable 9. A part or all of the control device 30 may be configured by, for example, a microcomputer or a microprocessor unit, or may be configured by an updatable device such as firmware. The control device 30 may be a program module or the like that is executed by a command from a CPU (Central Processing Unit) or the like.

<2. Configuration Example and Operation Example of Control Device>
Next, a configuration example and an operation example of the control device 30 will be described. As shown in FIG. 1, the control device 30 includes an acquisition unit 31, an extension detection unit 33, a cable extension characteristic database 35, and a drive control unit 37.

  The drive control unit 37 controls driving of the first actuator 11 and the second actuator 21. The drive control unit 37 drives the first actuator 11 to rotationally drive the first drive pulley 3, and winds the portion 9 a on one end side of the flexible cable 9 around the first drive pulley 3. As a result, the driven pulley 1 draws out the portion 9a on one end side of the flexible cable and winds up the portion 9b on the other end side. Along with this, the second drive pulley 5 leads out the portion 9 b on the other end side of the flexible cable 9.

  The drive control unit 37 drives the second actuator 21 to rotationally drive the second drive pulley 5, and winds the portion 9 b on the other end side of the flexible cable 9 around the second drive pulley 5. . As a result, the driven pulley 1 draws out the portion 9b on the other end side of the flexible cable and winds up the portion 9a on the one end side. Along with this, the first drive pulley 3 leads out a portion 9 a on one end side of the flexible cable 9.

  When the portions 9a and 9b of the flexible cable 9 are led out from the first drive pulley 3 and the second drive pulley 5, the first actuator 11 or the second actuator interlocked with the first drive pulley 3 is used. The rotational resistance of the second actuator 21 interlocked with the drive pulley 5 acts. For this reason, when the drive controller 37 controls the driving of the first actuator 11 or the second actuator 21, a constant tension is generated in the portions 9 a and 9 b of the flexible cable 9.

  When the winding radius r1 of the flexible cable 9 to the first driving pulley 3 and the winding radius r2 of the flexible cable 9 to the second driving pulley 5 are the same, the first driving pulley 3 and the second driving pulley 3 By rotating the two drive pulleys 5 at the same rotational speed and winding up the flexible cable 9, the driven pulley 1 rotates in the axial direction at substantially the same rotational speed. In other words, when the winding radius r1 of the flexible cable 9 to the first driving pulley 3 and the winding radius r2 of the flexible cable 9 to the second driving pulley 5 are the same, the first driving pulley 3 and the rotation amount of the second drive pulley 5 are substantially the same. However, when extension occurs in the flexible cable 9, a difference in rotation amount is generated corresponding to the extension amount ΔL.

  The acquisition unit 31 includes first position information related to the reference position of the portion 9a on one end side of the flexible cable 9, and second information related to the reference position of the portion 9b on the other end side of the flexible cable 9. Get location information. As described above, in the present embodiment, the acquisition unit 31 of the control device 30 acquires information about the rotation angle θ1 of the first drive pulley 3 as the first position information based on the sensor signal of the first rotation sensor 13. To do. The acquisition unit 31 acquires information about the rotation angle θ2 of the second drive pulley 5 as second position information based on the sensor signal of the second rotation sensor 23.

  The extension detection unit 33 detects extension of the flexible cable 9 based on the first position information and the second position information acquired by the acquisition unit 31. For example, when the winding radius r1 of the flexible cable 9 to the first drive pulley 3 and the winding radius r2 of the flexible cable 9 to the second drive pulley 5 are the same, the extension detection unit 33 is The rotation angle of the first drive pulley 3 (hereinafter also referred to as “first rotation angle”) θ1 as position information 1 and the rotation angle of the second drive pulley 5 (hereinafter referred to as “second position information”). , Also referred to as “second rotation angle.”) Based on a difference Δθ (for example, “θ2−θ1”) with respect to θ2, the extension of the flexible cable 9 is detected.

Specifically, for example, when the difference Δθ_α between the first rotation angle θ1_α and the second rotation angle θ2_α in an appropriate state at the start of use of the torque transmission device 10 is set to zero, the flexible cable 9 generated thereafter The elongation amount ΔL of can be expressed by the following formula (1).
ΔL = [(θ2−θ2_α) − (θ1−θ1_α)] × r (1)
r: radius of the first drive pulley 3 and the second drive pulley 5 (= r1 = r2)

For example, when the winding radius r1 of the flexible cable 9 to the first drive pulley 3 and the winding radius r2 of the flexible cable 9 to the second drive pulley 5 are different, the extension amount of the flexible cable 9 ΔL can be expressed by the following formula (2) instead of the above formula (1).
ΔL = (θ2−θ2_α) × r2− (θ1−θ1_α) × r1 (2)

  The extension detection unit 33 may consider the elastic characteristics of the flexible cable 9 when detecting the extension amount ΔL of the flexible cable 9. That is, the extension detection unit 33 can increase the detection accuracy of the extension amount ΔL of the flexible cable 9 by considering the amount of atrophy caused when the tension applied to the flexible cable 9 is removed. .

  When the extension detection unit 33 detects the extension amount ΔL of the flexible cable 9, the extension detection unit 33 may determine deterioration of the flexible cable 9 with reference to the cable extension characteristic database 35. The cable extension characteristic database 35 is data in which a change in the extension amount ΔL of the flexible cable 135 due to the use of the torque transmission device 10 is obtained in advance by experiment or simulation, and is a RAM (Random Access Memory) or ROM (Read Only Memory) or a storage device such as a CD-ROM or USB memory. Alternatively, the cable extension characteristic database 35 may not be stored in the control device 30 and may be accessible from the control device 30 via a wired or wireless communication unit.

  FIG. 2 shows an example of characteristic information stored in the cable extension characteristic database 35. The horizontal axis in FIG. 2 indicates the usage time of the torque transmission device 10, and the vertical axis indicates the extension amount ΔL of the flexible cable 9. In the example shown in FIG. 2, the extension amount ΔL of the flexible cable 9 increases at a relatively high increase rate immediately after the start of use of the torque transmission device 10 and then continues to increase gradually. When the end of use of the flexible cable 9 approaches, the increasing rate of the extension amount ΔL increases again, and the flexible cable 9 eventually breaks. The characteristic information shown in FIG. 2 is merely an example, and the characteristic of the flexible cable 9 is not limited to the illustrated example.

  The extension detection unit 33 may notify the user according to the extension amount ΔL of the flexible cable 9 by comparing the detected extension amount ΔL with the characteristic information of the cable extension characteristic database 35. For example, when the extension amount ΔL of the flexible cable 9 reaches the first reference value ΔL1 shown in FIG. 2, the extension detection unit 33 issues a warning by at least one of a warning display, a warning lamp, and a warning sound. You may go. Further, the extension detection unit 33 uses at least one of an exchange display, an exchange notification lamp, and an exchange notice sound when the extension amount ΔL of the flexible cable 9 reaches the second reference value ΔL2 shown in FIG. A warning operation may be performed.

  Thereby, the user of the torque transmission device 10 can know that the replacement time of the flexible cable 9 is approaching or has arrived. Therefore, it is possible to prevent the torque transmission from being suddenly stopped due to the flexible cable 9 being suddenly broken during use of the torque transmission device 10.

<3. Modification>
Next, a modification of the torque transmission device according to the present embodiment will be described. Whereas the torque transmission device 10 according to the above-described embodiment uses the first actuator 11 and the second actuator 21, the torque transmission device according to the modified example has the first drive pulley 3 and the second actuator by one actuator. 2 drive pulley 5 is rotated.

  FIG. 3 is a schematic diagram illustrating a configuration of a torque transmission device 10A according to a modification. The torque transmission device 10A includes a flexible cable 9, a first drive pulley 3, a second drive pulley 5, a driven pulley 1, an actuator 17, a first rotation sensor 13, and a second rotation. A sensor 23, a one-way clutch 27, a torsion spring 29, and a control device 30 are provided. The flexible cable 9, the first drive pulley 3, the second drive pulley 5, the driven pulley 1, the first rotation sensor 13, the second rotation sensor 23, and the control device 30 are torques according to the above embodiment. It can be configured in the same manner as each component of the transmission device 10.

  In the torque transmission device 10 according to the modification, the winding radius of the flexible cable 9 around the first drive pulley 3 and the winding radius of the flexible cable 9 around the second drive pulley 5 are the same. . The first drive pulley 3 and the second drive pulley 5 are supported by a common rotating shaft 19. The rotation shaft 19 is connected to the output shaft 17 a of the actuator 17 and is driven to rotate by the actuator 17. Similarly to the torque transmission device 10 according to the above-described embodiment, the actuator 17 can be an electric drive type rotary motor or a combination of an electric drive type linear motor and a power transmission mechanism. The actuator 17 can rotate the rotating shaft 19 forward and reverse.

  In the torque transmission device 10 </ b> A according to the modification, the second drive pulley 5 is fixedly supported with respect to the rotating shaft 19. That is, the second drive pulley 5 and the rotary shaft 19 are configured not to rotate relative to each other. On the other hand, the first drive pulley 3 is supported on the rotary shaft 19 via a one-way clutch 27. That is, the first drive pulley 3 can freely rotate relative to the rotation shaft 19 in one direction around the axis, while the relative rotation in the other direction around the axis is suppressed. ing.

  In the example of the torque transmission device 10 </ b> A shown in FIG. 3, when the rotary shaft 19 rotates in the rotation direction in which the second drive pulley 5 can wind the portion 9 b on the other end side of the flexible cable 9, Relative rotation between the drive pulley 3 and the rotary shaft 19 is possible. On the contrary, when the rotary shaft 19 rotates in the rotational direction in which the first drive pulley 3 can wind the portion 9 a on one end side of the flexible cable 9, the relative rotation between the first drive pulley 3 and the rotary shaft 19 is performed. Is suppressed. As the one-way clutch 27, a known one-way clutch such as a sprag type or a cam type is appropriately used. Normally, since there is a limit to the suppression torque that can suppress rotation by the one-way clutch, it is desirable to select the one-way clutch so that an appropriate suppression torque can be obtained according to the torque generated by the actuator to be used.

  The torsion spring 29 is flexible so that the flexible cable 9 is not detached from the first drive pulley 3, the second drive pulley 5 or the driven pulley 1 due to the extension of the flexible cable 9. The tension of the cable 9 is maintained. By the torsion spring 29, the tension is automatically maintained according to the extension of the flexible cable 9 without manually adjusting the tension of the flexible cable 9.

  Specifically, one end of the torsion spring 29 is fixed to the one-way clutch 27 fixed to the first drive pulley 3, and the other end is fixed to the rotating shaft 19. A central portion of the torsion spring 29 is wound around the rotary shaft 19. The torsion spring 29 urges the first drive pulley 3 via the one-way clutch 27 in a direction in which relative rotation with respect to the rotary shaft 19 is allowed, and always with respect to the first drive pulley 3. The tensile torque is applied. The spring load of the torsion spring 29 is appropriately set according to a desired tension generated in the flexible cable 9. In addition, the component for giving tension | tensile_strength to the flexible cable 9 is not restricted to a torsion spring.

  In the torque transmission device 10A according to the modified example, when the actuator 17 is not driven, a preload is applied to the flexible cable 9 in advance, and the tension of the flexible cable 9 is maintained. The preload may be provided manually. On the other hand, when the rotary shaft 19 is rotated by the actuator 17, the first drive pulley 3 and the second drive pulley 5 are rotationally driven as follows.

  For example, in FIG. 3, when the rotation shaft 19 rotates in the rotation direction in which the second drive pulley 5 winds the flexible cable 9, the first drive pulley 3 and the rotation shaft 19 are relatively moved by the function of the one-way clutch 27. It can be rotated. For this reason, the first drive pulley 3 is not rotated by the rotational torque of the rotating shaft 19. On the other hand, since the second drive pulley 5 rotates with the rotation of the rotary shaft 19, the flexible cable 9 is wound around the second drive pulley 5. As a result, the first drive pulley 3 rotates so as to lead out the flexible cable 9 by the tension of the flexible cable 9.

  In FIG. 3, when the rotary shaft 19 rotates in the rotation direction in which the first drive pulley 3 winds the flexible cable 9, the first drive pulley 3 rotates by the function of the one-way clutch 27. To rotate. Therefore, the flexible cable 9 is wound around the first drive pulley 3. At this time, the second drive pulley 5 fixed to the rotation shaft 105 is also rotated by the rotation torque of the rotation shaft 19, and the flexible cable 9 is led out.

  In this way, by repeating the forward drive or the reverse drive of the actuator 17, the driven pulley 1 is axially rotated in both directions, and a rotational torque is output. At that time, the tension of the flexible cable 9 is maintained substantially constant each time the actuator 17 rotationally drives the rotary shaft 19 in the rotational direction in which the second drive pulley 5 winds the flexible cable 9. become.

  In the torque transmission device 10 </ b> A according to the modified example, the rotation phase of the first drive pulley 3 is equal to the extension amount ΔL of the flexible cable 9 by the one-way clutch 27 and the torsion spring 29. Will be shifted from the rotational phase. The control device 30 can be configured in the same manner as the control device 30 of the torque transmission device 10 according to the above-described embodiment except that the drive control unit 37 controls the driving of one actuator 17.

  Even with the torque transmission device 10 </ b> A according to the modification, the extension detection unit 33 of the control device 30 can detect the extension amount ΔL of the flexible cable 9. Further, by performing a warning operation or an exchange notification operation according to the extension amount ΔL generated by the extension detection unit 33, the user or the like can know that the replacement time of the flexible cable 9 is approaching or has arrived. it can. Therefore, it is possible to prevent the torque transmission from being suddenly stopped due to the flexible cable 9 being suddenly broken during use of the torque transmission device 10.

<4. Application example to motion assist device>
Next, with reference to FIG. 4, an example in which the torque transmission device 10 according to the above embodiment is applied to a human body-mounted robot 100 as an operation assisting device will be described. FIG. 4 is an explanatory diagram illustrating an example of a human-mounted robot 100 that rotates the joint 120 with power generated by the first actuator 11 and the second actuator 21 of the torque transmission device 10. FIG. 4 is a schematic diagram shown for ease of understanding, and the torque transmission device 10 may actually be accommodated in, for example, a case or a bag and placed on the waist or back of a human body, or a joint. It may be disposed adjacent to the portion 120.

  The illustrated human body-mounted robot 100 includes a joint portion 120, and a first arm portion 112 and a second arm portion 114 that are coupled to be rotatable about the joint portion 120. The upper part of the first arm portion 112 is fixed to a mounting belt 102 that is wrapped around the waist of a human body. The lower portion of the second arm portion 114 is fixed to a mounting belt 104 that is wound around the thigh of the human body. The joint portion 120 is provided with the driven pulley 1, and the relative rotation between the first arm portion 112 and the second arm portion 114 around the joint portion 120 is transmitted via the flexible cable 9. It is driven by ten first actuators 11 and second actuators 21.

  For example, two flexible cables 9a and 9b are connected to the driven pulley 1 of the joint portion 120, and one of the flexible cables is sent out toward the joint portion 120, and the other flexible cable is connected to the joint pulley 120. By retracting from the portion 120, the second arm portion 114 rotates clockwise or counterclockwise with respect to the first arm portion 112. The respective ends of the flexible cables 9 a and 9 b are fixed or wound around the first drive pulley 3 or the second drive pulley 5 of the torque transmission device 10. The illustrated flexible cables 9a and 9b are configured as Bowden cables in which cables made of wire, resin, or the like are covered with covers 131 and 132, and one ends of the covers 131 and 132 are fixed to the first arm portion 112. The distal ends of the flexible cables 9 a and 9 b can be advanced and retracted with respect to the joint portion 120. The flexible cables 9a and 9b may be a single flexible cable 9 that is wound around the joint 120 and led out.

  In the human body wearing robot 100, for example, when a user (wearer) walks, the second arm portion 114 is rotated clockwise around the joint portion 120, thereby assisting the user to raise his / her foot. The For example, when the drive control unit 37 of the control device 30 detects that the user is trying to raise his / her foot by using a myoelectric potential sensor or a sensor for detecting the movement of the user's foot, the second actuator 21 can be driven to drive The flexible cable 9b is wound around the second drive pulley 5. As a result, the flexible cable 9 b moves backward from the joint portion 120, while the flexible cable 9 a is sent out toward the joint portion 120. As a result, the driven pulley 1 rotates clockwise, and the second arm portion 114 rotates clockwise around the joint portion 120 to generate a force that assists the user in raising the foot.

  On the other hand, when the user is going to lower the foot, the drive control unit 37 of the control device 30 drives the first actuator 11 to wind the flexible cable 9a around the first drive pulley 3. As a result, the flexible cable 9 a is retracted from the joint portion 120, while the flexible cable 9 b is sent out toward the joint portion 120. As a result, the driven pulley 1 rotates counterclockwise, and the second arm portion 114 rotates counterclockwise around the joint portion 120 to generate a force that assists the user in lowering the foot.

  In the human-body-mounted robot 100 according to the present embodiment, the extension detection unit 33 of the control device 30 transmits the power generated by the first actuator 11 and the second actuator 21 to the driven pulley 1 and the flexible cables 9a and 9b. Can be detected. Further, when the extension detection unit 33 performs a warning operation or an exchange notification operation in accordance with the extension amount ΔL of the flexible cables 9a and 9b, the user, the assistant, or the like until the flexible cables 9a and 9b are damaged. The flexible cables 9a and 9b can be exchanged. Therefore, it is possible to prevent sudden assistance operation from being obtained while using the human body-mounted robot 100.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above-described embodiment, as an application example of the torque transmission device, an operation assisting device that generates an assisting force for the user's operation is illustrated, but the present invention is not limited to such an example. The torque transmission device according to the present invention can be applied to various devices using pulleys and flexible cables.

  In the above embodiment, the extension amount ΔL of the flexible cable 9 is detected using information on the rotation angle detected by a rotation sensor such as a rotary encoder. However, the present invention is not limited to this example. For example, a portion 9 a on one end side of the flexible cable 9 led out from the driven pulley 1 to the first driving pulley 3 and the other end of the flexible cable 9 led out from the driven pulley 1 to the second driving pulley 5. A mark for determining the reference position may be attached to the portion 9b on the side, and the displacement of the movement amount between the two reference positions may be measured using an electromagnetic position sensor, an imaging sensor, or the like.

In the modification of the above embodiment, the rotation angle θ1 of the first drive pulley 3 and the rotation angle θ2 of the second drive pulley 5 are detected using two rotation sensors. It is not limited to. In the torque transmission device 10 </ b> A according to the modified example, the second drive pulley 5 is fixed to the rotary shaft 19, while the first drive pulley 3 is rotatable relative to the rotary shaft 19. Therefore, even if only one rotation sensor that detects the relative rotation angle Δθ between the rotating shaft 19 and the first drive pulley 3 is used, the extension amount ΔL of the flexible cable 109 can be detected by the following equation (3). it can.
ΔL = Δθ × r (3)

DESCRIPTION OF SYMBOLS 1 ... Drive pulley, 3 ... 1st drive pulley, 5 ... 2nd drive pulley, 9 ... Flexible cable, 10 ... Torque transmission apparatus, 11 ... 1st 13 ... 1st rotation sensor, 17 ... Actuator, 19 ... Rotating shaft, 21 ... 2nd actuator, 23 ... 2nd rotation sensor, 27 ... One way Clutch, 29 ... Torsion spring, 30 ... Control device, 31 ... Acquisition unit, 33 ... Extension detection unit, 35 ... Cable extension characteristic database, 37 ... Drive control unit, 100 ..Human body-mounted robots (motion assist devices)

Claims (7)

A flexible cable in which an intermediate portion is wound around a driven pulley and both end sides are fixed to a first drive pulley and a second drive pulley, respectively;
First position information related to a reference position of the flexible cable derived from the driven pulley to the first driving pulley and derived from the driven pulley to the second driving pulley. An acquisition unit for acquiring second position information related to a reference position of the flexible cable;
An extension detector for detecting extension of the flexible cable based on the first position information and the second position information;
A torque transmission device comprising:   The acquisition unit acquires rotation angle information of the first drive pulley as the first position information, and acquires rotation angle information of the second drive pulley as the second position information. Item 2. The torque transmission device according to Item 1. A common actuator for rotationally driving the first drive pulley and the second drive pulley;
The first drive pulley that allows relative rotation of the first drive pulley in one direction around the axis with respect to the rotary shaft that supports the first drive pulley, and that rotates in the other direction around the axis. A one-way clutch that suppresses the relative rotation of
The torque transmission device according to claim 1, comprising: A first actuator for rotationally driving the first drive pulley;
A second actuator for rotationally driving the second drive pulley;
The torque transmission device according to claim 1, comprising:   The torque transmission device according to claim 1, wherein the extension detection unit performs a warning operation when an extension amount of the flexible cable reaches a reference value. A first flexible cable having both ends fixed to the first drive pulley and the driven pulley,
A second flexible cable having both ends fixed to the second driving pulley and the driven pulley,
An acquisition unit that acquires first position information related to a reference position of the first flexible cable and second position information related to a reference position of the second flexible cable;
An extension detector for detecting extension of at least one of the first flexible cable and the second flexible cable based on the first position information and the second position information;
A torque transmission device comprising: The torque transmission device according to any one of claims 1 to 6,
A first arm member and a second arm member which are connected so as to be capable of relative movement and are subjected to relative movement by the torque transmission device;
A motion assisting device.