JP2014097550A - Rigidity variable driving device and joint driving mechanism - Google Patents

Abstract

[PROBLEMS] To provide a variable stiffness drive device that can be continuously and widely changed from low stiffness to high stiffness and capable of dynamic operation, and a joint drive mechanism including the variable stiffness drive device.
A variable stiffness drive device (100) is provided with a rod-shaped elastic member (2), a drive motor (5), a rotating shaft (4) connected to the drive motor (5), and a fitting hole (32) for fitting into the elastic member (2). And a transmission member 3 that rotates integrally with the rotation shaft 4 and transmits the rotational force of the rotation shaft 4 to the elastic member 2. In addition, the variable stiffness drive device 100 contacts the ultrasonic motor 6 that drives the transmission member 3 in the axial direction and a part of the elastic member 2 to restrain the elastic member 2 and moves integrally with the transmission member 3. And a restraining member 13 whose contact position with respect to the elastic member 2 moves in the axial direction. The elastic member 2 has a shape in which a cross-sectional secondary pole moment in a cross-section in a direction orthogonal to the axial direction Y decreases as the tip part 2a moves away from the axial direction Y.
[Selection] Figure 1

Description

  The present invention relates to a variable stiffness drive device that drives by adjusting stiffness, and a joint drive mechanism that includes the variable stiffness drive device.

  In recent years, humanoid robots have been researched on agile and flexible robots with dynamic characteristics close to those of living bodies. In relation to these research fields, Non-Patent Document 1 and Patent Document 1 disclose means for changing the elastic force of the suspension of the vehicle body and means for adjusting the joint rigidity.

  In Patent Document 1, the support point of the torsion bar is variable, and the effective length of the torsion bar can be changed to adjust the elastic force of the suspension.

  Further, in the joint mechanism design method described in Non-Patent Document 1, the joint rigidity can be adjusted by changing the distance between the support point of the leaf spring by the roller and the rod end surface. Thereby, the rigidity around the joint can be changed from high rigidity to low rigidity.

  Here, as a general viscoelastic model of biological muscle strength, it is known that when the muscle contraction force increases, the muscle elastic coefficient also increases. This indicates that the elastic coefficient of the muscle is not constant but is a non-linear characteristic that changes in proportion to the contractile force of the muscle. A variable stiffness drive device having such nonlinear stiffness characteristics is arranged at a joint portion of a robot or a power assist device, and the drive torque of the joint and the stiffness of the joint are adjusted and controlled to resemble a biological operation.

JP 2008-230469 A

Development of Force-Controlled Robot Arm Using Mechanical Impedance Adjustor Toshio Morita, Nobuyoshi Shimita, Takeo USogak 16 No. 7, pp1001-1006, 1998

  However, in robots and power assist devices, when an external force is applied softly, the operation of pushing back (hereinafter referred to as “operation with back drivability”) and the operation of positioning at a target position with high accuracy at high speed can be made compatible. It was difficult.

  In the operation having a very soft back drivability like the former, the joint rigidity needs to be close to zero. On the other hand, in the latter operation of positioning at the target position with high accuracy at high speed, it is necessary to make the joint rigidity as high as possible.

  In order to realize such operations with greatly different characteristics with the same robot, it is necessary to vary the joint stiffness and increase the variable ratio between the minimum stiffness value and the maximum stiffness value.

  Further, in order to enable smooth joint operation, it is necessary to continuously change the joint rigidity from a low rigidity state to a high rigidity.

  SUMMARY OF THE INVENTION Accordingly, the present invention provides a variable stiffness drive device that can be continuously and widely varied from low stiffness to high stiffness and capable of dynamic operation, and a joint drive mechanism including the stiffness variable drive device.

  The variable stiffness drive device of the present invention is formed to extend in the axial direction, is supported rotatably about an axis, and outputs a rotational force from the tip, a rotation drive unit, and drive of the rotation drive unit And a fitting hole that fits into the elastic member so as to be slidable in the axial direction, and rotates together with the rotating shaft to transmit the rotational force of the rotating shaft to the elastic member. A transmission member, a transmission member drive unit that drives the transmission member in the axial direction, and a drive member that is provided on the transmission member and contacts the part of the elastic member to restrain the elastic member. And a restraining member that moves in the axial direction integrally with the transmission member, and a contact position with respect to the elastic member moves in the axial direction, wherein the elastic member is in a cross section in a direction orthogonal to the axial direction. Sectional secondary pole maume Doo is characterized in that it is a reduced form with distance in the axial direction from the tip.

  According to the present invention, since the effective length of the elastic member can be changed, the torsional rigidity of the distal end portion of the elastic member can be changed. In addition, since the elastic member decreases as the cross-sectional secondary pole moment increases from the tip, the torsional rigidity can be changed in accordance with the cross-sectional secondary pole moment of the portion to be constrained. Accordingly, a large variable rigidity can be obtained, and a wide range of rigidity can be varied from low rigidity to high rigidity.

It is explanatory drawing which shows schematic structure of the rigidity variable drive device which concerns on 1st Embodiment. It is a figure for demonstrating the torsional rigidity of the output end of a rigidity variable drive device. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the variable rigidity drive device which concerns on 1st Embodiment becomes the minimum. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the rigidity variable drive device which concerns on 1st Embodiment becomes the maximum. It is a figure which shows the relationship between the effective length of an elastic member, and torsional rigidity. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the variable rigidity drive device which concerns on 2nd Embodiment becomes the minimum. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the variable rigidity drive device which concerns on 2nd Embodiment becomes the maximum. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the rigidity variable drive device which concerns on 3rd Embodiment becomes the minimum. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the rigidity variable drive device which concerns on 3rd Embodiment becomes the maximum. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the rigidity variable drive device which concerns on 4th Embodiment becomes the minimum. It is explanatory drawing which shows the state from which the torsional rigidity of the output end of the rigidity variable drive device which concerns on 4th Embodiment becomes the maximum. It is explanatory drawing which shows schematic structure of the joint drive mechanism provided with the rigidity variable drive device in 5th Embodiment. It is explanatory drawing which shows schematic structure of the joint drive mechanism provided with the rigidity variable drive device in 6th Embodiment. It is explanatory drawing which shows schematic structure of the joint drive mechanism provided with the rigidity variable drive device in 7th Embodiment.

  FIG. 1 is an explanatory diagram showing a schematic configuration of a variable stiffness drive apparatus according to the first embodiment of the present invention. FIG. 1A shows a torsional moment, ie, a state where the torsional rigidity is minimum, and FIG. 1B shows a torsional moment, ie, a state where the torsional rigidity is maximum.

  The stiffness variable drive device 100 makes the torsional stiffness of the output end variable. The variable stiffness drive apparatus 100 includes a drive motor 5 that is an electromagnetic motor and a variable stiffness mechanism 1 as a rotational drive unit.

  The variable stiffness mechanism 1 is formed to extend in the axial direction Y, and is a rod-shaped elastic member 2 that outputs a rotational force from the tip 2a, a rotary shaft 4 that extends from the drive motor 5 in the axial direction Y, a transmission member 3, And an ultrasonic motor 6 which is a stiffness variable motor as a transmission member driving unit. The elastic member 2 is accommodated in the housing 12 so that the tip end portion 2a is exposed to the outside, and an output gear (output end) 10 is connected to the tip end portion 2a of the elastic member 2. The distal end portion 2a of the elastic member 2 is supported by a bearing 11 fixed to the housing 12 so as to be rotatable about a rotation center line (axis line) G, and movement in the axial direction Y is restricted by the bearing 11. Yes.

  The drive motor 5 is disposed outside the housing 12, and a rotating shaft 4 connected to a rotor (not shown) of the drive motor 5 extends through the inside of the housing 12. The rotating shaft 4 and the elastic member 2 are arranged coaxially. In the first embodiment, the rotary shaft 4 is formed integrally with the drive motor 5, but may be a separate body and is driven by the drive motor 5 via a gear mechanism (not shown). It may be.

  The transmission member 3 rotates integrally with the rotation shaft 4 and transmits the rotational force of the rotation shaft 4 to the elastic member 2. More specifically, the transmission member 3 is formed with a fitting hole 31 into which the rotary shaft 4 is fitted and a fitting hole 32 into which the elastic member 2 is fitted. In the first embodiment, the fitting hole 31 and the fitting hole 32 communicate with each other. The transmission member 3 is accommodated in the housing 12 so as to be slidable in the axial direction Y with respect to the housing 12.

  The rotating shaft 4 is inserted into the fitting hole 31 of the transmission member 3 so as to be slidable in the axial direction Y, and the elastic member 2 is inserted into the fitting hole 32 so as to be slidable in the axial direction Y.

  The rotating shaft 4 and the fitting hole 31 are formed in a quadrangular cross section, and the rotating shaft 4 is fitted in the fitting hole 31 with no backlash. Thereby, the transmission member 3 is fitted to the rotating shaft 4 in the section N in FIG. 1, and the transmitting member 3 rotates integrally with the rotating shaft 4. The transmission member 3 is higher in rigidity than the elastic member 2 and has a structure in which twisting about the rotation center line G does not occur. In other words, the elastic member 2 has a structure that is less rigid than the transmission member 3 and is twisted about the rotation center line G.

  The transmission member 3 is provided with a restraining member 13 that restrains the elastic member 2. The fitting hole 32 of the transmission member 3 is fitted to the elastic member 2 in the section M in FIG. 1, and the rotational force is transmitted to the elastic member 2 via the restraining member 13.

  In the first embodiment, the restraining member 13 includes two rollers 131 as a first rotating body and two rollers 132 as a second rotating body that are rotatably supported by the transmission member 3 so as to sandwich the elastic member 2. have. The roller 131 and the roller 132 are disposed to face each other with the elastic member 2 interposed therebetween. In FIG. 1, only the roller 131 is shown, and the roller 132 is not shown in FIG. 1, but is disposed at a position corresponding to the roller 131 on the paper surface of FIG. 1. Each of the rollers 131 and 132 is disposed in the vicinity of the opening end of the fitting hole 32 formed in the transmission member 3. Thus, the transmission member 3 is also a support member that supports the restraining member 13.

  The restraining member 13 comes into contact with a part of the outer periphery of the elastic member 2 to restrain the elastic member 2 and moves in the axial direction Y integrally with the transmission member 3 by driving the ultrasonic motor 6. As a result, the contact position (restraint position) of the restraining member 13 with respect to the elastic member 2 moves in the axial direction Y.

  The transmission member 3 can slide in the axial direction Y while restraining the twisting operation in the rotational direction around the rotation center line G at the contact position of the elastic member 2 by the rollers 131 and 132.

  The driving force of the drive motor 5 can be transmitted from the rotary shaft 4 to the output gear 10 via the transmission member 3, the restraining member 13 and the elastic member 2.

  A drive groove 3b extending in the circumferential direction is formed on the outer periphery of the transmission member 3, and a transmission member drive ring 9 fixed to the male screw 8 is disposed in contact with the drive groove 3b. The male screw 8 meshes with a female screw 7 supported by the housing 12 so as to be rotatable about the axis G.

  The ultrasonic motor 6 has a fixed portion 6b fixed to the housing 12, and a drive output portion 6a that rotates about the axis G with respect to the fixed portion 6b. The drive output portion 6a is fixed to the female screw 7. ing. Thereby, the internal thread 7 is rotated around the axis G by the ultrasonic motor 6.

  The male screw 8 meshed with the female screw 7 is supported by the housing 12 so as to be able to translate in the axial direction Y with respect to the housing 12. Therefore, the rotational movement of the female screw 7 is converted into a translational movement of the male screw 8 in the axial direction Y. When the male screw 8 moves in the axial direction Y, the transmission member 3 moves in the axial direction Y in a state where the transmission member 3 is allowed to rotate around the rotation center line G. Therefore, the transmission member 3 moves in the axial direction Y by the rotational drive of the ultrasonic motor 6.

  The material of the elastic member 2 is a spring steel or the like. When an external force about the axis G is applied to the output gear 10 with the rotation of the rotation shaft 4 fixed, the portion between the restraining member 13 and the tip 2a of the elastic member 2, that is, the effective lengths L1 and L2 The part (FIGS. 1 (a) and 1 (b)) is twisted.

When an external force is applied to the output gear 10, the torsional moment (load torque) is T, the torsional angle of the elastic member 2 is θ, the effective length of the elastic member 2 is L, the cross-sectional secondary pole moment Ip of the elastic member 2, the elasticity The lateral elastic modulus of the member 2 is G, and the torsional rigidity of the output gear 10 is K. These relational expressions are represented by the following expressions (1) and (2).
θ = (T × L) / (G × Ip) (1)
K = T / θ (2)

From the equations (1) and (2), the torsional rigidity K is expressed by the following equation (3).
K = (G × Ip) / L (3)

  From equation (3), the torsional rigidity K is proportional to the inverse of the size of the effective length L of the elastic member 2 and is proportional to the size of the cross-sectional secondary pole moment Ip of the elastic member 2. Therefore, the torsional rigidity of the output gear 10 can be changed by adjusting the value of one or both of the effective length L of the elastic member 2 and the cross-sectional secondary pole moment Ip.

  As shown in FIG. 1A, in the state where the torsional rigidity of the output gear 10 is the lowest, the transmission member 3 is slid by the ultrasonic motor 6, and the effective length of the elastic member 2 is L1, which is the longest. When an external force acts on the output gear 10, the torsional rigidity of the effective length L1 portion of the elastic member 2 is minimized.

  As shown in FIG. 1B, when the torsional rigidity of the output gear 10 is the highest, the transmission member 3 is slid by the ultrasonic motor 6, and the effective length of the elastic member 2 is L2, which is the shortest. When an external force acts on the output gear 10, the effective length L2 portion of the elastic member 2 is twisted, and the torsional rigidity is maximized.

  By moving the transmission member 3 provided between the drive motor 5 and the output gear 10 in the axial direction Y by the ultrasonic motor 6, the contact position (restraint position) of the restraining member 13 with respect to the elastic member 2 becomes the axial direction Y. Move to. Thereby, since the torsional moment of the elastic member 2 changes, the torsional rigidity in the rotation direction of the output gear 10 changes.

  2A and 2B are diagrams for explaining the torsional rigidity of the output end of the variable stiffness drive apparatus 100. FIG. 2A is a diagram showing a variable stiffness range by the ultrasonic motor 6, and FIG. FIG. 5 is a diagram showing a range of movement of a neutral position by the drive motor 5

  As shown in FIG. 2A, in the state where the effective length of the elastic member 2 is L1, the relationship between the torsional displacement (twisting angle) θ of the output gear 10 and the torsional torque T is a stiffness characteristic of Kmin. On the other hand, in the state where the effective length of the elastic member 2 is L2, the relationship between the torsional displacement θ and the torsional torque T becomes a stiffness characteristic of Kmax. The rigidity characteristics from Kmin to Kmax can be freely changed by the ultrasonic motor 6.

  As shown in FIG. 2B, the neutral position O (intersection where the torsional displacement θ and the torsional torque T are 0) of the rigidity characteristic shown in FIG. , Θm to θn can be freely moved in the range Δθ. Thereby, the torsional torque of the output gear 10 can be set to a desired value.

  FIG. 3 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus 100 according to the first embodiment of the present invention is minimized. FIG. 3A is a perspective view of the elastic member 2 and the restraining member 13 that restrains torsion, and FIG. 3B is a cross-sectional view of the restraining portion. FIG. 4 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus 100 according to the first embodiment of the present invention is maximized. 4A is a detailed view of the elastic member 2 and the restraining member 13 that restrains twisting, and FIG. 4B is a cross-sectional view of the restraining portion.

  As shown in FIGS. 3 and 4, the elastic member 2 has a shape in which a cross-sectional secondary pole moment in a cross section in a direction orthogonal to the axial direction Y decreases as the tip part 2 a moves away from the axial direction Y. That is, the cross-sectional secondary pole moment Ip (cross-sectional area) of the cross-sectional shape of the rod-shaped elastic member 2 gradually decreases as the bar-shaped elastic member 2 moves away from the output gear 10 in the axial direction Y.

  The cross-sectional shape of the elastic member 2 is negative when the effective length farthest from the output gear 10 is L1, and is positive when the effective length closest to the output gear 10 is L2. .

  More specifically, the elastic member 2 is formed on the outer periphery so as to extend in the axial direction Y, and is a first constrained surface 121 that is in contact with the rollers 131 and 131 and a first surface that is in contact with the rollers 132 and 132. It has a constrained surface 122 that is two constrained surfaces. The restricted surface 121 and the restricted surface 122 are planes parallel to each other.

  In the first embodiment, at least one of the restrained surfaces 121 and 122, both the restrained surfaces 121 and 122 are provided with ribs 123, the height of which decreases with increasing distance from the distal end portion 2a in the axial direction Y. 124 is provided.

  The rollers 131 and 132 are rotatably fitted to roller shafts 131a and 132a fixed to the transmission member 3. Accordingly, the rollers 131 and 132 are rotatably supported by the transmission member 3 via the roller shafts 131a and 132a.

  The two rollers 131 and 131 supported by the transmission member 3 are in contact with the constrained surface 121 of the elastic member 2, and the two rollers 132 and 132 supported by the transmission member 3 are constrained by the constrained surface 122 of the elastic member 2. The elastic member 2 is restrained from being twisted at these contact positions.

  In FIG. 3, the effective length L1 of the elastic member 2 when the elastic member 2 is constrained is the largest, and the cross-sectional secondary pole moment Ip at the position where the elastic member 2 is constrained is the smallest. The torsional rigidity of the output gear 10 can be greatly reduced by both the effect of increasing the effective length L and the effect of reducing the cross-sectional secondary pole moment Ip.

  On the other hand, in FIG. 4, the effective length L2 of the elastic member 2 when the elastic member 2 is constrained is the smallest, and the cross-sectional secondary pole moment Ip at the position where the elastic member 2 is constrained is the largest. The torsional rigidity of the output gear 10 can be greatly increased by both the effect of reducing the effective length L and the effect of increasing the sectional secondary pole moment Ip.

  FIG. 5 is a diagram showing the relationship between the effective length L of the elastic member 2 and the torsional rigidity K. As shown in FIG. In FIG. 5, a curve 41 indicates the characteristic of the elastic member 2 of the first embodiment. On the other hand, the curved dotted line 42 shows a characteristic of a structure in which the elastic member does not have a region where the value of the cross-sectional secondary pole moment Ip in the longitudinal position is reduced as a comparative example.

As shown in FIG. 5, the curve 41 is a curve that passes through the intersection of the effective length L1 and the minimum torsional rigidity Kmin and the intersection of the effective length L2 and the maximum torsional rigidity Kmax. Curve 41 reduces the torsional rigidity of K _Ip (Ip decrease) in FIG. 5 when compared with a curved dotted line 42 having a structure in which the elastic member does not have a region where the value of the second-order secondary moment Ip is reduced. Can do. Therefore, by sliding the transmission member 3 from the effective length L1 to L2, it is possible to continuously and widely change the rigidity of the output gear 10 from the low rigidity Kmin to the high rigidity Kmax.

  As described above, according to the first embodiment, since the effective length L of the elastic member 2 can be changed, the torsional rigidity of the distal end portion 2a of the elastic member 2 can be changed. Further, the elastic member 2 can change the torsional rigidity corresponding to the cross-sectional secondary pole moment of the portion to be constrained because the secondary cross-pole moment decreases with distance from the tip 2a. Accordingly, a large variable rigidity can be obtained, and a wide range of rigidity can be varied from low rigidity to high rigidity.

  Further, since the transmission member 3 changes the effective length while restraining the torsion of the rod-like elastic member 2, it is possible to continuously change the torsional rigidity of the output gear 10 (that is, the distal end portion 2 a) that is the output end. It becomes.

[Second Embodiment]
Next, a variable stiffness drive apparatus according to a second embodiment of the present invention will be described. FIG. 6 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus according to the second embodiment of the present invention is minimized. FIG. 7 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus according to the second embodiment of the present invention is maximized. 6A is a perspective view of the elastic member and the restraining member, and FIG. 6B is a cross-sectional view of the restraining portion. Fig.7 (a) is a perspective view of an elastic member and a restraint member, FIG.7 (b) is sectional drawing of a restraint part.

  In the second embodiment, the elastic member and the restraining member are different from those in the first embodiment, and other configurations are the same as those in the first embodiment. Therefore, the same reference numerals are given to the same configurations. The description is omitted.

  The elastic member 202 of the second embodiment is formed to extend in the axial direction Y, is supported by the bearing 11 (see FIG. 1) so as to be rotatable about the axis G, and outputs a rotational force from the distal end portion 202a. Further, the restraining member 213 of the second embodiment is provided on the transmission member 3, comes into contact with a part of the elastic member 202 to restrain the elastic member 202, and the transmission member is driven by driving the ultrasonic motor 6 (see FIG. 1). 3 in the axial direction Y. As a result, the contact position (restraint position) of the restraining member 213 with respect to the elastic member 202 moves in the axial direction Y.

  As shown in FIGS. 6 and 7, the elastic member 202 has a shape in which the cross-sectional secondary moment in a cross section perpendicular to the axial direction Y decreases as the tip part 202 a moves away in the axial direction Y. In other words, the cross-sectional secondary pole moment Ip (cross-sectional area) of the bar-shaped elastic member 202 gradually decreases as it moves away from the output gear 10 in the axial direction Y.

  The restraining member 213 includes a roller 231 as a first rotating body and a roller 232 as a second rotating body that are rotatably supported by the transmission member 3 so as to sandwich the elastic member 202. Each of the rollers 231 and 232 is disposed in the vicinity of the opening end of the fitting hole 32 formed in the transmission member 3. The roller 231 and the roller 232 are disposed to face each other with the elastic member 202 interposed therebetween.

  The rollers 231 and 232 are rotatably fitted to roller shafts 231 a and 232 a fixed to the transmission member 3. Accordingly, the rollers 231 and 232 are rotatably supported by the transmission member 3 via the roller shafts 231a and 232a.

  The elastic member 202 is formed on the outer periphery so as to extend in the axial direction Y. The elastic member 202 is a restricted surface 221 that is a first restricted surface that contacts the roller 231 and a restricted surface 222 that is a second restricted surface that contacts the roller 232. Have The restrained surface 221 and the restrained surface 222 are planes parallel to each other.

  The roller 231 supported by the transmission member 3 contacts the restrained surface 221 of the elastic member 202, and the roller 232 supported by the transmission member 3 contacts the restrained surface 222 of the elastic member 202. The twist of the elastic member 202 is restrained at the contact position.

  In the second embodiment, the elastic member 202 is formed such that the portion 223 between the constrained surface 221 and the constrained surface 222 becomes thinner as it moves away from the distal end portion 202a in the axial direction Y. . By changing the wall thickness in this way, the cross-sectional secondary pole moment can be reduced as the distance from the tip 202a in the axial direction Y increases.

  As described above, according to the second embodiment, since the effective length of the elastic member 202 can be changed, the torsional rigidity of the distal end portion 202a of the elastic member 202 can be changed. Further, since the elastic member 202 decreases as the cross-sectional secondary pole moment moves away from the tip end portion 202a, the torsional rigidity can be changed in accordance with the cross-sectional secondary pole moment of the portion to be constrained. Accordingly, a large variable rigidity can be obtained, and a wide range of rigidity can be varied from low rigidity to high rigidity.

  Further, since the transmission member 3 changes the effective length while restraining the torsion of the rod-like elastic member 202, it is possible to continuously change the torsional rigidity of the output gear 10 (that is, the distal end portion 202a) that is the output end. It becomes.

  In addition, if the structure is such that the value of the cross-sectional secondary pole moment of the elastic member decreases as it moves away from the output gear 10, the outer shape of the elastic member does not change and the thickness of the material is such that the inside is hollow. The same effect can be obtained even with a changing elastic member.

[Third Embodiment]
Next, a variable stiffness drive apparatus according to a third embodiment of the present invention will be described. FIG. 8 is an explanatory diagram illustrating a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus according to the third embodiment of the present invention is minimized. FIG. 9 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus according to the third embodiment of the present invention is maximized. FIG. 8A is a perspective view of the elastic member and the restraining member, and FIG. 8B is a cross-sectional view of the restraining portion. FIG. 9A is a perspective view of the elastic member and the restraining member, and FIG. 9B is a cross-sectional view of the restraining portion.

  In the third embodiment, the elastic member and the restraining member are different from those in the first embodiment, and other configurations are the same as those in the first embodiment. Therefore, the same reference numerals are given to the same configurations. The description is omitted.

  The elastic member 302 of the third embodiment is formed to extend in the axial direction Y, is supported by the bearing 11 (see FIG. 1) so as to be rotatable about the axis G, and outputs a rotational force from the distal end portion 302a. In addition, the restraining member 313 of the third embodiment is provided on the transmission member 3, comes into contact with a part of the elastic member 302 to restrain the elastic member 302, and the transmission member is driven by driving the ultrasonic motor 6 (see FIG. 1). 3 in the axial direction Y. Accordingly, the contact position (restraint position) of the restraining member 313 with respect to the elastic member 302 moves in the axial direction Y.

  As shown in FIGS. 8 and 9, the elastic member 302 has a shape in which a cross-sectional secondary pole moment in a cross section perpendicular to the axial direction Y decreases as the tip part 302 a moves away in the axial direction Y. In other words, the cross-sectional secondary pole moment Ip (cross-sectional area) of the bar-shaped elastic member 302 gradually decreases as the bar-shaped elastic member 302 moves away from the output gear 10 in the axial direction Y.

  The restraining member 313 includes a roller portion 331 as a first rotating body and a roller portion 332 as a second rotating body that are rotatably supported by the transmission member 3 so as to sandwich the elastic member 302. Each of the roller portions 331 and 332 is disposed in the vicinity of the opening end of the fitting hole 32 formed in the transmission member 3. The roller portion 331 and the roller portion 332 are disposed to face each other with the elastic member 302 interposed therebetween.

  The roller portion 331 includes a large roller 331a as a first large roller, a pair of small rollers 331b and 331b as a pair of first small rollers having a smaller diameter than the large roller 331a, disposed on both sides of the large roller 331a, Consists of. These rollers 331a, 331b, and 331b are rotatably fitted to a roller shaft 331c fixed to the transmission member 3. Therefore, each roller 331a, 331b, 331b is rotatably supported by the transmission member 3 via the roller shaft 331c.

  The roller section 332 includes a large roller 332a as a second large roller, a pair of small rollers 332b and 332b as a pair of second small rollers having a smaller diameter than the large roller 332a, disposed on both sides of the large roller 332a, Consists of. These rollers 332a, 332b, and 332b are rotatably fitted to a roller shaft 332c fixed to the transmission member 3. Accordingly, the rollers 332a, 332b, and 332b are rotatably supported by the transmission member 3 via the roller shaft 331c.

  The elastic member 302 is formed to extend in the axial direction Y on the outer periphery, and is a restrained surface 321 that is a first restrained surface that contacts the roller portion 331 and a restrained surface that is a second restrained surface that contacts the roller portion 332. It has a surface 322.

  The constrained surface 321 contacts the pair of small rollers 331b and 331b from the first end 321a to the intermediate portion 321c in the axial direction Y, and contacts the large roller 331a from the intermediate portion 321c to the second end 321b. As shown in FIG. The first end 321a is an end in the vicinity of the distal end portion 302a on the constrained surface 321. The second end 321b is the end farthest from the tip end portion 302a in the constrained surface 321.

  The constrained surface 322 contacts the pair of small rollers 332b and 332b from the first end 322a to the intermediate portion 322c in the axial direction Y, and contacts the large roller 332a from the intermediate portion 322c to the second end 322b. As shown in FIG. The first end 322a is an end in the vicinity of the distal end portion 302a on the constrained surface 322. The second end 322b is the end farthest from the tip end portion 302a in the constrained surface 322.

  More specifically, the rod-like elastic member 2 has an H-shaped cross-sectional shape with a thick end portion and a thin central portion in the range of Ls close to the output gear 10, and the value of the cross-sectional secondary pole moment Ip in this range. Is getting bigger. On the other hand, in the range of Lm of the elastic member 2, the cross-sectional shape has a “−” shape, and the value of the cross-sectional secondary pole moment Ip in this range is smaller than the range of Ls.

  That is, the elastic member 302 has a pair of surfaces 351 and 351 that are part of the constrained surface 321 that contacts the pair of small rollers 331b and 331b in the range of Ls. The elastic member 302 has a pair of surfaces 352 and 352 that are part of the constrained surface 322 that contacts the pair of small rollers 332b and 332b in the range of Ls. The elastic member 302 includes a surface 353 that is a part of the constrained surface 321 that contacts the large roller 331a in the range of Lm and a part of the constrained surface 322 that contacts the large roller 332a in the range of Lm. And a certain surface 354.

  The two large rollers 331a and 332a among the restraining members 313 composed of a total of six rollers are arranged on the restrained surfaces 321 and 322 of the elastic member 302 in the range of Lm, which is a negative cross-sectional portion of the elastic member 302. The contact is made with a width of Wm, and the twist of the elastic member 302 is restrained.

  Of the restraining member 313, the four small rollers 331 b and 332 b are disposed on both sides of the restrained surfaces 321 and 322 of the elastic member 302 in the range of Ls, which is the H-shaped cross-sectional portion of the elastic member 302. The contact is made with the width of Ws, and the twist of the elastic member 302 is restrained.

  As described above, in the third embodiment, the elastic member 302 is constrained by the plurality of rollers 331a and 331b and the rollers 332a and 332b having different diameters. In this way, by providing each roller to be constrained with a diameter difference, there is an effect that the value of the cross-sectional secondary pole moment Ip at a position close to the distal end portion 302a of the elastic member 302 can be greatly increased. Thereby, the maximum stiffness Kmax can be set to a value higher than the value in the configuration of the first embodiment described with reference to FIG. Therefore, the configuration of the third embodiment is effective in specifications that require a higher value of the maximum stiffness Kmax.

  In the third embodiment, the rollers 331a, 331b, 332a, and 332b come into contact with the elastic member 302 whose cross-sectional shape has changed to restrain torsion, and therefore follow the change in the cross-sectional shape of the elastic member 302 to make contact. No special roller displacement mechanism or the like is required. Therefore, the rigidity of the transmission member unit itself including the rollers 331a, 331b, 332a, 332b and the roller shafts 331c, 332c is not lowered.

  In the third embodiment, as shown in FIGS. 8 and 9, the twist of the elastic member 302 is constrained by two types of rollers having different diameters. However, two or more types of rollers having different outer diameters are used. May be arranged.

[Fourth Embodiment]
Next, a variable stiffness drive apparatus according to a fourth embodiment of the present invention will be described. FIG. 10 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus according to the fourth embodiment of the present invention is minimized. FIG. 11 is an explanatory diagram showing a state in which the torsional rigidity of the output end of the variable stiffness drive apparatus according to the fourth embodiment of the present invention is maximized. FIG. 10A is a perspective view of the elastic member and the restraining member, and FIG. 10B is a cross-sectional view of the restraining portion. FIG. 11A is a perspective view of the elastic member and the restraining member, and FIG. 11B is a cross-sectional view of the restraining portion.

  In the fourth embodiment, the elastic member and the restraining member are different from those in the first embodiment, and other configurations are the same as those in the first embodiment. Therefore, the same reference numerals are given to the same configurations. The description is omitted.

  The elastic member 402 of the fourth embodiment is formed to extend in the axial direction Y, is supported by the bearing 11 (see FIG. 1) so as to be rotatable about the axis G, and outputs a rotational force from the distal end portion 402a. The elastic member 402 is formed in the shape of a rod having a truncated cone shape that becomes thinner as it moves away from the tip end portion 402a. Further, the restraining member 413 of the fourth embodiment is provided on the transmission member 3, comes into contact with a part of the elastic member 402 to restrain the elastic member 402, and the transmission member is driven by driving the ultrasonic motor 6 (see FIG. 1). 3 in the axial direction Y. Accordingly, the contact position (restraint position) of the restraining member 413 with respect to the elastic member 402 moves in the axial direction Y.

  As shown in FIGS. 10 and 11, the elastic member 402 has a shape in which the secondary secondary moment in a cross section in the direction orthogonal to the axial direction Y decreases as it moves away from the distal end portion 402 a in the axial direction Y. In other words, the cross-sectional secondary pole moment Ip (cross-sectional area) of the bar-shaped elastic member 402 gradually decreases as it moves away from the output gear 10 in the axial direction Y.

  A through hole 420 is formed in the elastic member 402 so as to penetrate in a direction orthogonal to the axial direction Y. The through hole 420 is formed in a long hole shape extending in the axial direction Y. The through-hole 420 has a pair of constrained surfaces 421 and 422 that extend in the axial direction Y and face each other.

  The restraining member 413 has a roller portion 431 as a cylindrical body that is provided by being inserted through the through hole 420 so as to contact the pair of restrained surfaces 421 and 422. The roller portion 431 is disposed in the vicinity of the opening end of the fitting hole 32 formed in the transmission member 3.

  The roller portion 431 includes a small roller 431a serving as a small cylindrical portion, and a pair of large rollers 431b and 431b serving as a pair of large cylindrical portions having a larger diameter than the small roller 431a disposed on both sides of the small roller 431a. Become. These rollers 431a, 431b, and 431b are rotatably fitted to a roller shaft 431c fixed to the transmission member 3. Therefore, each roller 431a, 431b, 431b is rotatably supported by the transmission member 3 via the roller shaft 431c.

  In the axial direction Y, the constrained surface 421 contacts the pair of large rollers 431b and 431b from the first end 421a to the intermediate portion 421c, and contacts the small roller 431a from the intermediate portion 421c to the second end 421b. As shown in FIG. The first end 421a is an end in the vicinity of the distal end portion 402a on the constrained surface 421. The second end 421b is the end farthest from the tip end portion 402a in the constrained surface 421.

  In the axial direction Y, the constrained surface 422 contacts the pair of large rollers 431b and 431b from the first end 422a to the intermediate portion 422c, and contacts the small roller 431a from the intermediate portion 422c to the second end 422b. As shown in FIG. The first end 422a is an end in the vicinity of the distal end portion 402a on the constrained surface 422. The second end 422b is the end farthest from the tip end portion 402a in the constrained surface 422.

  That is, the elastic member 402 is in contact with the pair of large rollers 431b and 431b in the range of Ls, and a pair of surfaces 451 and 451 that are a part of the constrained surface 421 and a pair of the constrained surface 422. And surfaces 452 and 452. In addition, the elastic member 402 has a surface 453 that is a part of the constrained surface 421 and a surface 454 that is a part of the constrained surface 422 that are in contact with the small roller 431a within a range of Lm.

  Specifically, the small roller 431a contacts the restrained surfaces 421 and 422 of the elastic member 402 with a width of Wm, and restrains the twisting of the elastic member 402. Further, the large rollers 431b and 431b are in contact with the restrained surfaces 421 and 422 of the elastic member 402 with a width of Ws to restrain the twisting of the elastic member 402.

  As described above, also in the fourth embodiment, similarly to the third embodiment, the value of the cross-sectional secondary pole moment Ip at a position close to the distal end portion 402a of the elastic member 402 can be extremely increased. Accordingly, the maximum rigidity of the output gear 10 (tip portion 402a) can be set large.

  In the fourth embodiment, as shown in FIGS. 10 and 11, the twisting of the elastic member 402 is constrained by two types of rollers having different diameters. However, two or more types of rollers having different outer diameters are used. May be arranged.

[Fifth Embodiment]
Next, the joint drive mechanism provided with the variable stiffness drive apparatus according to the fifth embodiment will be described. FIG. 12 is an explanatory diagram illustrating a schematic configuration of a joint drive mechanism including the variable stiffness drive device according to the fifth embodiment. 12A is a top view of the joint drive mechanism, and FIG. 12B is a side view of the joint drive mechanism. The joint drive mechanism of the fifth embodiment is a robot arm 5000, and includes a link 51 that is a first link, a link 52 that is a second link, and a base 53. One end of the link 51 is fixed to the base 53. The other end of the link 51 and one end of the link 52 are connected by a joint J so as to be rotatable. Specifically, a bearing 54 is fixed to the other end of the link 51, and a shaft 55 rotatably supported by the bearing 54 is fixed to one end of the link 52. A joint gear 56 that is a bevel gear is connected to one end of the shaft 55.

  In the fifth embodiment, the robot arm 5000 includes the variable stiffness drive apparatus 100 of the first embodiment that drives the joint J, and the variable stiffness drive apparatus 100 is fixed to the base 53.

  The output gear 10 of the variable stiffness drive apparatus 100 is a bevel gear and meshes with the joint gear 56. Therefore, when the output gear 10 rotates, the joint gear 56 rotates around the bearing 54 and the link 52 turns around the bearing 54. The drive torque of the drive motor 5 of the variable stiffness drive apparatus 100 is controlled by a control circuit (not shown). Also, the torsional moment of the ultrasonic motor 6 of the variable stiffness drive apparatus 100 is controlled by another control circuit (not shown). The link 52 is driven by these control circuits.

  FIG. 12B shows a state in which the link 52 is turned to the position of the joint angle θp by driving the drive motor 5. The torsional moment of the output gear 10 can be freely changed by driving the ultrasonic motor 6 at the position of the joint angle θp and sliding the transmission member 3. In this way, the joint angle by the drive motor 5 and the torsional rigidity around the joint J by the ultrasonic motor 6 can be controlled independently.

  According to the fifth embodiment, the torsional rigidity of the link 52 around the joint J can be freely set from low rigidity to high rigidity regardless of the joint angle, and both dynamic operation and high positioning operation can be achieved.

[Sixth Embodiment]
Next, the joint drive mechanism provided with the variable stiffness drive apparatus according to the sixth embodiment will be described. FIG. 13 is an explanatory diagram illustrating a schematic configuration of a joint drive mechanism including the variable stiffness drive device according to the sixth embodiment. FIG. 13A shows a top view of the joint drive mechanism, and FIG. 13B shows a side view of the joint drive mechanism. The joint drive mechanism of the sixth embodiment is a robot arm 6000, and includes a link 51 that is a first link, a link 52 that is a second link, and a base 53. One end of the link 51 is fixed to the base 53. The other end of the link 51 and one end of the link 52 are connected by a joint J so as to be rotatable. Specifically, a bearing 54 is fixed to the other end of the link 51, and a shaft 55 rotatably supported by the bearing 54 is fixed to one end of the link 52. At both ends of the shaft 55, joint gear ₅₆ 1, 56 ₂ are connected a bevel gear.

In the sixth embodiment, the robot arm 6000 includes the two variable stiffness drive devices 100 ₁ and 100 ₂ of the first embodiment that drive the joint J. The variable stiffness drive devices 100 ₁ and 100 ₂ are The base 53 is fixed. The two variable stiffness drive devices 100 ₁ , 100 ₂ have the same characteristics and are antagonistically arranged at the joint J. That is, the two variable stiffness drive devices 100 ₁ and 100 ₂ are disposed on both sides of the link 51.

Output gear 10 ₁ of a rigid variable drive apparatus 100 ₁ is a bevel gear meshes with the joint gear 56 _1. Further, the output gear 10 _{and second} rigid variable drive device 100 ₂ is a bevel gear meshes with the joint gear 56 _2. The configuration around the bearing 54 of the stiffness variable driving devices 100 ₁ and 100 ₂ is the same as that of the fifth embodiment, and the description thereof is omitted.

By a rigid variable drive apparatus ₁₀₀ 1, 100 ₂ antagonized arrangement, when driving the joint gear ₅₆ 1, 56 ₂ in the same direction, the rigidity changing drive device ₁₀₀ 1, 100 ₂ sum of the driving torque, is possible to give to the link 52 it can.

Further, when the rigidity changing drive device ₁₀₀ 1, 100 ₂ drives the joint gear ₅₆ 1, 56 ₂ in opposite directions, the difference in the driving torque of the rigid variable drive apparatus ₁₀₀ 1, 100 _2, may be provided to link 52 .

The rigidity variable drive apparatus ₁₀₀ 1, 100 ₂ made to have a difference in driving torque for driving the link 52, backlash (play between the gears) and the output gear ₁₀ 1, 10 ₂ and the joint gear ₅₆ 1, 56 ₂ small can do.

Thereby, high positioning with respect to the target position becomes possible. As described above, in the fourth embodiment, by arranging the _two stiffness variable drive devices 100 ₁ and 100 ₂ in an antagonistic manner, a large joint drive torque and a higher positioning operation can be performed.

[Seventh Embodiment]
Next, the joint drive mechanism provided with the variable stiffness drive apparatus according to the seventh embodiment will be described. FIG. 14 is an explanatory diagram illustrating a schematic configuration of a joint drive mechanism including the variable stiffness drive device according to the seventh embodiment. FIG. 14A is a side view of the joint drive mechanism, and FIG. 14B is a front view of the joint drive mechanism. The joint drive mechanism according to the seventh embodiment is a power assist device 7000, and includes a link 701 that is a first link and a link 702 that is a second link. One end of the link 701 and one end of the link 702 are connected by a joint J so as to be able to turn.

  More specifically, a bearing 704 is fixed to one end of the link 701, and a joint gear 703 that is a bevel gear rotatably supported by the bearing 704 is fixed to one end of the link 702.

  In the seventh embodiment, the power assist device 3000 includes the variable stiffness drive device 100 of the first embodiment that drives the joint J, and the variable stiffness drive device 100 is fixed to the link 701.

  The output gear 10 of the variable stiffness drive apparatus 100 is a bevel gear and meshes with the joint gear 703. Therefore, when the output gear 10 rotates, the joint gear 703 rotates around the bearing 704 and the link 702 turns around the bearing 704.

  The power assist device 7000 is attached to the lower limb of the human body H. The link 701 is disposed on the thigh Hc portion of the human body H, and is fixed to the thigh Hc with a belt 705. The link 702 is disposed on the lower leg Ha of the human body H and is fixed to the lower leg Ha with a belt 706.

  The elastic member 2 of the variable stiffness drive apparatus 100 is disposed in parallel with the thigh Hc. By changing the effective length of the elastic member 2, the torque and rigidity around the joint gear 703 are varied. Accordingly, the joint torque around the knee joint Hb is assisted. The variable stiffness drive device 100 can transmit the driving force to the lower leg Ha by turning the link 702.

  The drive motor 5 and the ultrasonic motor 6 of the variable stiffness drive apparatus 100 are also driven by the control circuit (not shown) described in the fifth embodiment.

  Hereinafter, an explanation will be given by taking the knee joint flexion and extension as an example. In the operation in which the knee joint Hb is bent deeply from the relatively extended posture as shown in FIG. 14A, the knee joint is driven by the driving force of the drive motor 5 while the output gear 10 is made to have low rigidity by the ultrasonic motor 6. Lead Hb to the bending motion. At this time, an external force is acting on the output gear 10 due to the gravity of the human body H or the like. At the same time, the drive motor 5 is driven by a drive torque that works to lock the rotation of the rotating shaft 4 (see FIG. 1) or to act as a brake against the external force acting on the output gear 10. Then, torsional displacement occurs in the elastic member 2 due to the difference between the drive torque of the drive motor 5 and the torque of the output gear 10 due to external force. That is, torsional energy is accumulated in the elastic member 2.

  Next, when the effective length L of the elastic member 2 is shortened by the ultrasonic motor 6 from the posture in which the knee joint Hb is bent and the torsional rigidity is increased, the accumulated twisting energy of the elastic member 2 can be increased. . When the knee joint Hb is stretched and jumps in a short time, an agile and dynamic movement is possible by releasing the increased torsional accumulated energy while being driven by the drive motor 5.

  Further, in a relatively slow walking motion, the torsional rigidity is set to an intermediate level by the ultrasonic motor 6 when landing. Thereby, the impact of landing can be absorbed by the elastic member 2. After kicking up the ground by driving the drive motor 5, the ultrasonic motor 6 makes the output gear 10 the minimum rigidity so that a natural and uncomfortable walking motion can be obtained.

  In addition, since the variable stiffness drive apparatus 100 can freely change the torsional rigidity and the drive torque of the output gear 10 in conjunction with each other, it is possible to perform appropriate power assist corresponding to the human body's leg strength and complicated posture. Become. In the seventh embodiment, the power assist device is configured around the knee joint of the human body, but may be applied to other joint parts such as the upper limbs of the human body and the living body.

  The present invention is not limited to the embodiments described above, and many modifications can be made by those having ordinary knowledge in the art within the technical idea of the present invention.

  In the fifth to seventh embodiments, the case where the variable stiffness drive apparatus is the variable stiffness drive apparatus 100 of the first embodiment has been described. However, the variable stiffness drive apparatus of the second to fourth embodiments is described. Also good.

  In the fifth to seventh embodiments, the case where the variable stiffness drive device is applied to a robot arm or a power assist device has been described. However, the present invention is not limited to this, and other robots such as legged robots are used. It can also be applied to nursing robots.

  In the first to fourth embodiments, the case where a ring type ultrasonic motor is used as the transmission member drive unit has been described. However, an electromagnetic motor or a solenoid may be used.

DESCRIPTION OF SYMBOLS 2 ... Elastic member, 2a ... Tip part, 3 ... Transmission member, 4 ... Rotary shaft, 5 ... Drive motor (rotation drive part), 6 ... Ultrasonic motor (transmission member drive part), 13 ... Restraint member, 32 ... Fitting Joint hole, 100 ... variable stiffness drive

Claims (9)

An elastic member that extends in the axial direction, is supported rotatably about the axis, and outputs a rotational force from the tip;
A rotation drive unit;
A rotating shaft that rotates by driving the rotation driving unit;
A fitting member that is formed to be fitted into the elastic member so as to be slidable in the axial direction, and that rotates integrally with the rotating shaft to transmit the rotational force of the rotating shaft to the elastic member;
A transmission member driving section for driving the transmission member in the axial direction;
The elastic member is provided on the transmission member, contacts the elastic member and restrains the elastic member, and moves in the axial direction integrally with the transmission member by driving the transmission member driving unit to contact the elastic member. A restraining member whose position moves in the axial direction,
The elastic variable drive device according to claim 1, wherein the elastic member has a shape in which a secondary secondary moment in a cross section in a direction orthogonal to the axial direction decreases with increasing distance from the distal end in the axial direction.   2. The variable stiffness drive apparatus according to claim 1, wherein the restraining member includes a first rotating body and a second rotating body that are rotatably supported by the transmission member so as to sandwich the elastic member.   The elastic member has a first constrained surface that contacts the first rotating body and a second constrained surface that contacts the second rotating body. The rigidity variable drive device according to claim 2.   The rib which becomes low as it leaves | separates from the said front-end | tip part to the said axial direction is formed in at least one of the said 1st to-be-restrained surface and the said 2nd to-be-restrained surface. 4. The variable stiffness drive device according to 3.   The elastic member is characterized in that a portion between the first constrained surface and the second constrained surface is formed thin as the distance from the tip portion in the axial direction increases. 4. The variable stiffness drive device according to 3. The first rotating body includes a first large roller and a pair of first small rollers disposed on both sides of the first large roller and having a smaller diameter than the first large roller,
The second rotating body includes a second large roller and a pair of second small rollers disposed on both sides of the second large roller and having a smaller diameter than the second large roller,
The first constrained surface is in contact with the pair of first small rollers from the first end to the intermediate portion in the vicinity of the tip portion in the axial direction, and from the intermediate portion to the tip portion. The farthest second end is formed with a step so as to contact the first large roller,
The second constrained surface is in contact with the pair of second small rollers from the first end to the intermediate portion in the axial direction, and from the intermediate portion to the second end, the second 4. The variable stiffness drive device according to claim 3, wherein the rigidity variable drive device is formed with a step so as to contact the large roller. The elastic member has a pair of constrained surfaces extending in the axial direction, and a through hole penetrating in a direction orthogonal to the axial direction is formed.
2. The variable stiffness drive device according to claim 1, wherein the restraining member is a cylindrical body provided to be inserted through the through hole so as to contact the pair of restrained surfaces. The cylindrical body has a small cylindrical portion and a pair of large cylindrical portions disposed on both sides of the small cylindrical portion and having a larger diameter than the small cylindrical portion,
The pair of constrained surfaces are in contact with the pair of large cylindrical portions from the first end to the middle portion in the vicinity of the tip portion in the axial direction, and are the most from the middle portion to the tip portion. The variable rigidity drive device according to claim 7, wherein a step is formed so as to come into contact with the small cylindrical portion up to the far second end. The first link,
A second link articulated to the first link;
A joint drive mechanism comprising: the variable stiffness drive device according to claim 1 that drives the joint.

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