JP2014097548A - Rigidity variable mechanism, rigidity variable driving device and joint driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously vary rigidity from low rigidity to high rigidity to be capable of performing a dynamic behavior.SOLUTION: A rigidity variable mechanism 100 comprises: an output arm 8; a solid cam 2 including a cam surface 2a; and cam followers 3A, 3B which moves, in accordance with displacement of the output arm 8, relative to the solid cam 2 while contacting with the cam surface 2a. The rigidity variable mechanism 100 includes compression coil springs 4A, 4B which press the cam followers 3A, 3B against the cam surface 2a and supply the output arm 8 with rigidity according to an inclination angle of the cam surface 2a. The rigidity variable mechanism 100 includes an ultrasonic motor 7 which relatively moves the cam followers 3A, 3B on the cam surface 2a in an orthogonal direction orthogonal to a direction along the track of the cam followers 3A, 3B moving on the cam surface 2a in accordance with displacement of the output arm 8. The cam surface 2a is formed so that a curve shape of the cross section on the track becomes different according to a position of the orthogonal direction.

Description

  The present invention relates to a stiffness variable mechanism that adjusts stiffness, a stiffness variable drive device that includes the stiffness variable mechanism, and a joint drive device that includes the stiffness variable 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 controlling the joint stiffness and joint stiffness.

  In “VS-JOINT” described in Non-Patent Document 1, a cam roller is brought into direct contact with a cam disk by the force of a compression spring. When the cam disk rotates and a position difference is generated between the cam disk and the cam roller, the cam roller is displaced in the vertical direction (the direction perpendicular to the rotation direction). At this time, the compression spring is compressed, and the spring force applies a force to the cam roller. This component force is used as the rigidity of the joint. The joint rigidity can be adjusted by moving the spring base slider supporting the fixed end of the compression spring to change the force of the cam roller.

  Further, the joint mechanism described in Patent Document 1 includes a support member, an arm, and an elastic member, and the angle of the elastic member biased to the arm can be changed, so that the rigidity of the rotating shaft changes nonlinearly. It is configured.

  Here, in a general viscoelastic model of the muscle strength of an organism, the muscle elastic coefficient increases as the muscle contraction force increases. This indicates that the elastic coefficient of the muscle is not constant but is a nonlinear characteristic that changes in proportion to the contractile force of the muscle. A stiffness variable mechanism or actuator having such a nonlinear stiffness characteristic is arranged at the joint portion, and the driving torque of the joint and the stiffness of the joint are adjusted and controlled to resemble the biological operation.

JP 2009-34774 A

Sebastian Wolf and Gerd Hirzinger DLR - German Aerospace Center Institute of Robotics and Mechatronics D-82234 Wessling, Germany: A New Variable Stiffness Design (VS-JOINT) 2008 IEEE International Conference on Robotics and Automation Pasadena, CA, USA, May 19-23 , 2008

  However, in humanoid robots, it is difficult to achieve both the operation of pushing back when soft external force is applied (hereinafter referred to as “operation with back drivability”) and the operation of positioning at a target position with high accuracy at high speed. It was.

  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.

  Accordingly, the present invention provides a variable stiffness mechanism that can be continuously varied from low stiffness to high stiffness, and capable of dynamic operation, a stiffness variable drive device equipped with the stiffness variable mechanism, and a joint drive equipped with the stiffness variable drive device. To provide an apparatus.

  The stiffness variable mechanism according to the present invention includes a displacement member that can be displaced by an external force, a solid cam having a cam surface, and a relative displacement relative to the solid cam while contacting the cam surface as the displacement member is displaced. A cam follower that moves, an elastic member that urges the cam follower to the cam surface and imparts rigidity to the displacement member according to an inclination angle of the cam surface, and the cam follower on the cam surface. Moving means relative to a direction orthogonal to the direction along the track on the cam surface of the cam follower that moves with the displacement of the cam follower, and the cam surface has a cross-section of the track in the track The curved shape is different depending on the position in the orthogonal direction.

  According to the present invention, the stiffness coefficient can be changed actively and freely. Therefore, a wide range of stiffness from low stiffness to high stiffness that cannot be realized with a simple passive spring structure is possible.

It is explanatory drawing which shows schematic structure of the rigidity variable mechanism which concerns on 1st Embodiment. It is explanatory drawing which shows the operation | movement of the cam follower with respect to the solid cam in 1st Embodiment. It is a figure which shows the characteristic of the rigidity variable mechanism which concerns on 1st Embodiment. It is explanatory drawing which shows schematic structure of the rigidity variable mechanism which concerns on 2nd Embodiment. It is explanatory drawing which shows the structure of the cam follower in 3rd Embodiment. It is detail drawing which shows the principal part of the rigidity variable mechanism which concerns on 4th Embodiment. It is a figure which shows the characteristic of the rigidity variable mechanism which concerns on 4th Embodiment. It is explanatory drawing which shows schematic structure of the rigidity variable drive device which concerns on 5th Embodiment. It is explanatory drawing of operation | movement of the rigidity variable drive device which concerns on 5th Embodiment. It is a figure which shows the characteristic of the variable rigidity drive device which concerns on 5th Embodiment. It is sectional drawing which shows the rigidity variable drive device which concerns on 6th Embodiment. It is sectional drawing which shows the rigidity variable drive device which concerns on 7th Embodiment. It is explanatory drawing of the joint drive device which concerns on 8th Embodiment. It is a side view which shows the joint drive device concerning 9th Embodiment.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[First Embodiment]
1A and 1B are explanatory views showing a schematic configuration of a variable stiffness mechanism according to the first embodiment of the present invention. FIG. 1A is a sectional view of the variable stiffness mechanism, and FIG. 1B is a side view of the variable stiffness mechanism. FIG.

  The translational variable stiffness mechanism 100 includes a housing 9 including a pair of plate members 9a and 9b and a connecting member 9c that connects the plate member 9a and the plate member 9b. The variable stiffness mechanism 100 includes an output arm 8 as a displacement member supported by a plate member 9a of the housing 9 via a linear bearing 10 so as to be linearly movable in the direction of the arrow X along the axis G by an external force, and a cam A solid cam 2 having a surface 2a.

  The solid cam 2 has a cylindrical shape centered on the axis G. The cam surface 2 a is a surface of a cam groove formed on the side surface of the cylinder in the circumferential direction, and is formed symmetrically with respect to the cross section including the axis G. The cam surface 2a is formed in a curved surface having a shape in which the inclination angle gradually and smoothly changes (gradually changes) around the entire circumference near the center.

  More specifically, the cam surface 2a has a lower groove line position (180 °) opposite to the upper groove line position (0 °) of the cylinder, as shown in the YY cross section of FIG. Is the maximum width, and the curved shape of the cam surface 2a is a gently inclined surface. The position of the lower groove line (270 °) opposed to the position of the upper groove line (90 °) shown in the side view of FIG. 1B is the minimum width, and the curved surface shape of the cam surface 2a is It has a steep slope.

  The output arm 8 includes a shaft portion 80 extending in the direction of the arrow X along the axis G from the output end 8a, and two branch portions 81 and 82 that branch from the shaft portion 80 to a position facing the cam surface 2a. And have.

  The variable stiffness mechanism 100 includes two cam followers 3A and 3B that move relative to the three-dimensional cam 2 while contacting the cam surface 2a as the output arm 8 is displaced in the arrow X direction. . The cam followers 3A and 3B are arranged at two locations so as to coincide with the opposing cam groove widths on the cam surface 2a.

  The variable stiffness mechanism 100 includes two compression coil springs 4A and 4B as elastic members that bias the cam followers 3A and 3B toward the cam surface 2a. The compression coil springs 4A and 4B give the output arm 8 rigidity according to the inclination angle of the cam surface 2a. In addition, the variable stiffness mechanism 100 includes an ultrasonic motor 7 as a moving unit that rotationally drives the solid cam 2 around the axis G.

  In the first embodiment, the component force in the relative movement direction of the reaction force generated by the elastic deformation (compression deformation) of the compression coil springs 4A and 4B accompanying the relative movement between the three-dimensional cam 2 and the cam followers 3A and 3B, The output end 8a of the output arm 8 is made rigid.

  Here, when a plurality of cross sections of the solid cam 2 including the axis G are defined, the cam surface 2a has a curved shape in each cross section, and each curve follows the cam follower 3A when the output arm 8 is displaced in the arrow X direction. It becomes 3B orbit. In other words, the contour line of the cam surface 2a when the cross section of the three-dimensional cam 2 is assumed becomes the track of the cam followers 3A and 3B.

  The cam surface 2a has a curved shape of a cross-section in the track depending on the position in the orthogonal direction perpendicular to the direction along the track on the cam surface of the cam followers 3A and 3B that move with the displacement of the output arm 8. It is formed as follows. In other words, the cam surface 2a is formed so that the contour shape of the contour line differs depending on the position in the orthogonal direction perpendicular to the direction in which the contour line extends on the cam surface 2a. That is, the cam surface 2a has a portion whose inclination angle changes according to the position in the orthogonal direction orthogonal to the direction along the track. In this way, since the curve shape of the track is different in each cross section, the change in the inclination angle of the curve is different in each track.

  One member of the three-dimensional cam 2 and the cam followers 3A and 3B, in the first embodiment, the cam followers 3A and 3B are supported by the branch portions 81 and 82 of the output arm 8 so as to be displaced together with the output arm 8. Specifically, the cam followers 3A and 3B are rotatably supported by the cam follower support shafts 6A and 6B, and the cam follower support shafts 6A and 6B are orthogonal to the output arm 8 via the linear bearings 5A and 5B. It is supported so as to be linearly movable in the Z direction (radial direction, radial direction). Thereby, the cam followers 3A and 3B roll on the cam surface 2a of the three-dimensional cam 2 by the displacement of the output arm 8 in the arrow X direction.

  The compression coil springs 4A and 4B are fitted on the cam follower support shafts 6A and 6B. The compression coil springs 4A and 4B bias the cam followers 3A and 3B in the Z direction so that the cam followers 3A and 3B come into contact with the cam surface 2a.

  The ultrasonic motor 7 has a fixed portion 7 a and a drive output portion 7 b, the fixed portion 7 a is fixed to the plate member 9 b of the housing 9, and the drive output portion 7 b is fixed to the three-dimensional cam 2. And the drive output part 7b rotates centering on the axis line G with respect to the fixing | fixed part 7a.

  The ultrasonic motor 7 drives the other member of the three-dimensional cam 2 and the cam followers 3A and 3B, that is, the three-dimensional cam 2 in the first embodiment. By this rotary ultrasonic motor 7, the three-dimensional cam 2 rotates around the axis G in the orthogonal direction (rotation direction around the axis G) perpendicular to the direction along the track of the cam followers 3A, 3B. By the rotational drive of the three-dimensional cam 2 by the ultrasonic motor 7, the cam followers 3A and 3B move along the track on the cam surface 2a of the cam follower 3 that moves with the displacement of the output arm 8 with respect to the cam surface 2a. It moves relatively in the orthogonal direction orthogonal to. By rotating the three-dimensional cam 2 in this way, the cam groove width and inclination angle can be changed. That is, the ultrasonic motor 7 can change the trajectory in which the cam followers 3A and 3B roll and move along the cam surface of the three-dimensional cam 2 when the output end 8a of the output arm 8 moves in the arrow X direction. Become. Since each track has a different curved shape in the orthogonal direction perpendicular to the direction along the track, the rigidity of the output end 8a of the output arm 8 can be changed.

  FIG. 2 is an explanatory diagram showing the operation of the cam follower 3 (3A, 3B) with respect to the solid cam 2 of the variable stiffness mechanism 100. FIG. The inclination angle of the cam surface 2 a of the three-dimensional cam 2 with respect to the cam follower 3 can be set by rotating the three-dimensional cam 2. FIG. 2A shows a state in which the rotational position of the solid cam 2 is 0 ° and the cam follower 3 is positioned at the maximum width of the cam groove of the solid cam 2. FIG. 2B shows a state in which the rotation position of the three-dimensional cam 2 is 45 ° and the cam follower 3 is positioned at the intermediate width of the cam groove of the three-dimensional cam 2. FIG. 2C shows a state in which the rotational position of the solid cam 2 is 90 ° and the cam follower 3 is positioned at the minimum width of the cam groove of the solid cam 2. As shown in FIG. 2, the curved shape of the trajectory of the cam follower 3 differs depending on the position in the orthogonal direction.

An external force acts on the output arm 8, the horizontal component force of the reaction force generated by the displacement of the compression coil spring 4 (4 </ b> A, 4 </ b> B) is F, and the cam follower 3 is perpendicular to the solid cam 2 by the force of the compression coil spring 4. The acting force is f, and the inclination angle of the cam surface 2a of the solid cam 2 is θ. Then, these relational expressions are represented by the following expression (1).
F = f x tanθ (1)

  From the equation (1), the horizontal component force F is determined by the inclination angle θ of the cam surface 2 a of the three-dimensional cam 2 and the force f of the compression coil spring 4. Therefore, by making the cam surface 2a a non-linear curved surface, the horizontal component force F has a non-linear characteristic.

In FIG. 2 (a), acts on the external force F _a is output arm 8, the cam follower 3 represents a state where the moving rolling from the position Xa is a bottom of the three-dimensional cam 2 to the position Xm (displacement). In FIG. 2 (a), which rolls and moves along the cam surface 2a, the cam follower 3 indicated by a dotted line has _a biasing force of fa by the compression coil spring 4 acting vertically, and the inclination angle at which the cam follower 3 contacts the cam surface 2a is an angle. the θ _a. Therefore, the cam follower 3 generates _a horizontal component force Fa.

In FIG. 2 (b), acts on the external force F _b is the output arm 8, the cam follower 3 represents a state where the moving rolling from the position Xa is a bottom of the three-dimensional cam 2 to the position Xm. In FIG. 2 (b), which is rolled along the cam surface 2 a, the dotted cam follower 3 has an inclination angle at which the urging force of f _b by the force of the compression coil spring 4 acts vertically, and the cam follower 3 contacts the cam surface 2 a. It is the angle θ _b. Thus the cam follower 3 generates a horizontal component force F _b.

In FIG. 2C, even if an external force acts on the output arm 8, the cam follower 3 is balanced with the inclination angle of the cam surface 2a in contact with the urging force of the compression coil spring 4, and the amount of movement that rolls along the cam surface 2a is as follows. Few. The biasing force acting vertically on the compression coil spring 4 is also small. 2 in (c) which moves rolling along the cam surface 2a, the dotted line of the cam follower 3, the biasing force of f _c by the force of the compression coil spring 4 acts vertically, the inclination angle which the cam follower 3 is brought into contact with the cam surface 2a It is the angle θ _c. Thus the cam follower 3 generates a horizontal component force F _c.

  FIG. 3 is a diagram showing the characteristics of the variable stiffness mechanism 100, showing the relationship between the horizontal component force and the displacement in each state of FIGS. 2 (a), 2 (b) and 2 (c). The vertical axis represents the horizontal component force F, and the horizontal axis represents the displacement (movement amount) X of the output arm 8 (that is, the cam follower 3).

In state L _a in FIG. 2 (a), the horizontal component force F _a force even if there is a change in the displacement X horizontal component is slowly has changed position Xm is low. State L _b in FIG. 2 (b), the horizontal component force F _b is relatively large at the position Xm rigid with the change in the displacement X is also varied continuously. In state L _c in FIG. 2 (c), the displacement X is's smaller little f _c, has a horizontal component force F _c is also linearly very large since the inclination angle theta _c increases sharply.

  Since the property of returning to the original state when an external force is applied is rigidity, the rigidity of the output arm 8 (output end 8a) of the rigidity variable mechanism 100 of the first embodiment is the inclination between the compression coil spring 4 and the three-dimensional cam 2. A linear characteristic can be obtained by designing the angle to be a straight line. In addition, nonlinear rigidity characteristics can be obtained by designing the inclination angle into a curve.

  Furthermore, by rotating the solid cam 2 around the axis G, the inclination angle of the cam surface 2a contacting the cam followers 3A and 3B can be changed, and the rigidity characteristics can be varied.

  As described above, according to the first embodiment, the stiffness coefficient can be changed actively and freely, so that a wide range of stiffness can be varied from low stiffness to high stiffness that cannot be realized with a simple passive spring structure. Become.

  Since the solid cam 2 has the cam surface 2a having a gradually changed shape, the forces of the cam followers 3A and 3B can be continuously varied.

[Second Embodiment]
Next, a stiffness variable mechanism according to the second embodiment of the present invention will be described. FIG. 4 is an explanatory diagram showing a schematic configuration of a stiffness variable mechanism according to the second embodiment of the present invention. 4A is a side view of the variable stiffness mechanism, FIG. 4B is a front view of the variable stiffness mechanism, FIG. 4C is a cross-sectional view taken along the line HH of the variable stiffness mechanism, and FIG. FIG. 4E is an II cross-sectional view of the variable stiffness mechanism, and FIG. 4F is a JJ cross-sectional view of the variable stiffness mechanism.

  In the second embodiment, the variable stiffness mechanism 200 is a rotary type. The stiffness variable mechanism 200 is configured to generate stiffness in the rotational direction about the axis M in FIG. The variable stiffness mechanism 200 includes a housing 209, a shaft 210 projecting from the housing 209, and an output gear as a displacement member supported by the shaft 210 so as to be rotatable in the direction of arrow R about the axis G by an external force. 212 and a three-dimensional cam 202.

  The housing 209 is formed in a cylindrical shape, and the shaft 210 protrudes from the bottom of the housing 209. The three-dimensional cam 202 is rotatably supported by a shaft 210 fixed to a cylindrical casing 209.

  The solid cam 202 has a cylindrical shape centered on the axis M, and has two cam surfaces 202a and 202b. The cam surfaces 202a and 202b are formed in plane symmetry with respect to the cross section HH including the axis M and the cross section orthogonal to the cross section HH and including the axis M. The cam surfaces 202a and 202b have a wide cam groove width and a gentle inclined surface in the II section shown in FIG. 4E, and the JJ section shown in FIG. 4F. Then, the cam groove width is narrow and the inclined surface has a steep shape. The cam surfaces 202a and 202b are formed as curved surfaces having a shape in which the cam groove width and the inclined surface are gradually and smoothly changed (gradually changed) from the II section to the JJ section.

  The variable stiffness mechanism 200 includes two cam followers 203A and 203B that move relative to the three-dimensional cam 202 while contacting the cam surfaces 202a and 202b as the output gear 212 is displaced in the direction of arrow R. ing.

  The stiffness variable mechanism 200 includes two compression coil springs 204A and 204B as elastic members that bias the cam followers 203A and 203B to the cam surfaces 202a and 202b. The compression coil springs 204A and 204B give the output gear 212 rigidity according to the inclination angles of the cam surfaces 202a and 202b. The variable stiffness mechanism 200 includes an ultrasonic motor 207 as a moving unit that drives the cam followers 203A and 203B in the direction of the axis M.

  One member of the three-dimensional cam 202 and the cam followers 203A and 203B, in the second embodiment, the three-dimensional cam 202 is supported (fixed) on the output gear 212 so as to be displaced together with the output gear 212.

  Similar to the translation type, the cam followers 203A and 203B urged to the three-dimensional cam 202 by the compression coil springs 204A and 204B are rotatably supported by the cam follower support shafts 206A and 206B so that the cam followers 202A and 202b can roll and move. It has become.

  The cam follower support shafts 206A and 206B are supported by linear bearings 205A and 205B fixed to the cam follower drive ring 208 so as to be able to translate in a radial direction (radial direction) about the axis M. The cam followers 203A and 203B located on the NN cross section shown in FIG. 4 (d) are arranged at two locations so as to contact the opposing cam surfaces 202a and 202b, with the center line M as the center. It can roll and move along the cam surfaces 202a and 202b while rotating.

  The compression coil springs 204A and 204B are fitted on the cam follower support shafts 206A and 206B. The compression coil springs 204A and 204B bias the cam followers 203A and 203B in the radial direction (radial direction) so that the cam followers 203A and 203B come into contact with the cam surfaces 202a and 202b.

  In the rotary type variable stiffness mechanism 200, the curve (contour line) in the cross section perpendicular to the axis M of the cam surfaces 202a and 202b becomes the trajectory on which the cam followers 203A and 203B move.

  The cam followers 203A and 203B move relative to the cam surfaces 202a and 202b when the three-dimensional cam 202 is displaced in accordance with the displacement of the output gear 212. The cam surfaces 202a and 202b of the three-dimensional cam 202 correspond to the positions of the cross-sectional curved shapes of the cam followers 203A and 203B in the orthogonal direction (direction in which the axis M extends) perpendicular to the direction along the track on the cam surface. Are formed differently. That is, the cam surfaces 202a and 202b have a portion where the inclination angle changes according to the position in the orthogonal direction orthogonal to the direction along the track. In this way, since the curve shape of the track is different in each cross section, the change in the inclination angle of the curve is different in each track.

  The ultrasonic motor 207 includes a fixing unit 207a and a drive output unit 207b, and the fixing unit 207a is fixed to the housing 209. The drive output unit 207b is fixed to the shaft 211. The drive output unit 207b rotates about the axis M with respect to the fixed unit 207a.

  The cam follower drive ring 208 has an internal thread on the inner diameter, and the cylindrical casing 209 has an external thread that meshes with the internal thread of the cam follower drive ring 208. The cam follower drive ring 208 is rotationally driven by the ultrasonic motor 207 via the shaft 211 and can be translated parallel to the axis M.

  That is, the ultrasonic motor 207 drives the other member of the three-dimensional cam 202 and the cam followers 203A and 203B, in the second embodiment, the cam followers 203A and 203B in the direction of the axis M. By driving the cam followers 203A and 203B by the ultrasonic motor 207, the cam followers 203A and 203B are relatively relative to each other in the orthogonal direction perpendicular to the direction along the track on the cam surface of the three-dimensional cam 202 that moves in accordance with the displacement of the output gear 212. Move on. That is, the position of the cam followers 203A and 203B in the direction of the axis M (N-N cross section) can be slid in the translation direction.

  As described above, the cam followers 203A and 203B are translated, so that the width and the inclination angle of the cam groove can be changed. In other words, the ultrasonic motor 207 can change the trajectory along which the cam followers 203A and 203B roll and move along the cam surfaces 202a and 202b of the three-dimensional cam 202 when the output gear 212 is displaced in the arrow R direction. . Since each track has a different curved shape in the orthogonal direction perpendicular to the direction along the track, the rigidity of the output gear 212 can be changed.

  The direction of the force generated in the output gear 212 is an arrow R direction (rotational direction) in FIG. When an external force acts on the output gear 212 in the direction of arrow R (rotation direction), the cam followers 203A and 203A move, and an urging force due to compression of the compression coil springs 204A and 204B is generated toward the axis M. The component force in the relative movement direction of the reaction force generated by the displacement of the compression coil springs 204A and 204B in the arrow R direction (rotation direction) at this time becomes the rigidity of the output gear 212.

  In the second embodiment, the rigidity of the output gear 212 is designed so that the inclination angles of the compression coil springs 204A and 240B and the cam surfaces 202a and 202b of the three-dimensional cam 202 are linear as in the translation type of the first embodiment. To obtain a linear characteristic. In addition, non-linear stiffness characteristics can be obtained by designing the inclination angle into a curve. Furthermore, the rigidity characteristics can be varied by moving the cam followers 203A and 230B in the translation direction.

[Third Embodiment]
In the first and second embodiments, the case where the cam follower has a roller shape has been described. In the third embodiment, the structure of another cam follower will be described.

  FIG. 5 is an explanatory diagram showing the configuration of the cam follower in the third embodiment. In FIG. 5A, the cam follower 503 is slidably disposed in the recess of the cam follower support shaft 505. The compression coil spring 504 is disposed between the bottom surface of the recess of the cam follower support shaft 505 and the cam follower 503. Thereby, the cam follower 503 urged to the cam surface 2a by the compression coil spring 504 can slide on the cam surface 2a. The cam follower 503 has a cylindrical shape with a spherical tip, and is preferably formed of a metal material having a low friction coefficient and high hardness.

  In FIG. 5B, the cam follower 513 has a spherical shape, and is slidably disposed in the recess of the cam follower support shaft 515. The compression coil spring 514 is disposed between the bottom surface of the recess of the cam follower support shaft 515 and the cam follower 513. Thereby, the cam follower 513 urged to the cam surface 2a by the compression coil spring 514 can roll on the cam surface 2a.

  In FIG. 5C, the cam follower 523 has a spherical shape and is urged to the cam surface 2 a by the compression coil spring 524 via the follower support shaft 525. Thereby, the cam follower 523 can roll on the cam surface 2a.

  As described above, the cam follower may have any of a sliding configuration that slides with respect to the cam surface of the three-dimensional cam and a rolling configuration that rolls with respect to the cam surface.

[Fourth Embodiment]
Next, the stiffness variable mechanism according to the fourth embodiment of the present invention will be described. In the fourth embodiment, the cam surface of the three-dimensional cam has a shape having a portion that makes the displacement of the compression coil spring constant. FIG. 6 is a detailed view showing the main part of the variable stiffness mechanism according to the fourth embodiment of the present invention. FIG. 6A shows a translational rigidity variable mechanism, and FIG. 6B shows a rotation rigidity variable mechanism. FIG. 7 is a view showing the characteristics of the variable stiffness mechanism according to the fourth embodiment of the present invention. The displacement X of the output member and the displacement of the compression coil spring accompanying the relative movement between the solid cam and the cam follower. The relationship between the generated reaction force and the component force F in the relative movement direction is shown.

  As shown in FIG. 6A, the cam follower 3 urged by the compression coil spring 4 to the cam surface 2a of the three-dimensional cam 2 is rotatably supported by the cam follower support shaft 6, and moves along the cam surface 2a. It can be done.

  As shown in FIG. 6A, the cam surface 2a of the three-dimensional cam 2 has an elastic deformation amount of the compression coil spring 4 when the cam follower 3 moves on the cam surface 2a as the compression coil spring 4 is displaced. ) Has a flat region (straight region) S, which is a constant part. In the plane region S, even if the cam follower 3 moves, the compression amount (elastic deformation amount) of the compression coil spring 4 does not change and is constant. From F = f × tan θ according to the equation (1), the inclination angle θ is 0 °, and the component force F in the horizontal direction (relative movement direction) is 0. Therefore, in the planar region S, the rigidity change (elastic coefficient) can be zero as shown in FIG. Other configurations of the variable stiffness mechanism are the same as those in the first embodiment shown in FIG.

  Further, as shown in FIG. 6B, the cam follower 203 urged to the cam surface 202a of the three-dimensional cam 202 by the compression coil spring 204 is rotatably supported by the cam follower support shaft 206, and the cam surface 202a is supported. It can be rolled and moved.

  As shown in FIG. 6B, when the cam follower 203 moves on the cam surface 202a with the displacement of the compression coil spring 204, the cam surface 202a has a constant (elastic deformation amount) of the compression coil spring 204. It has a curved region T which is a portion. The curved region T is formed by a concentric circular arc curve coaxial with the rotation center. Within this curved region T, even if the cam follower 203 moves, the compression amount of the compression coil spring 204 does not change and the inclination angle θ does not change, so the component force F in the relative movement direction becomes zero. Therefore, as shown in FIG. 7, the characteristic has a region in which the stiffness change is zero. The configuration of the stiffness variable mechanism is the same as that of the second embodiment shown in FIG.

  As described above, in the configuration according to the fourth embodiment, a rigidity characteristic having an area in which the rigidity change is 0 (zero) can be obtained, so that a very soft operation is possible.

[Fifth Embodiment]
Next, a variable stiffness drive apparatus according to a fifth embodiment of the present invention will be described. FIG. 8 is an explanatory diagram showing a schematic configuration of a variable stiffness drive apparatus according to a fifth embodiment of the present invention, in which FIG. 8A is a VV sectional view of the variable stiffness drive apparatus, and FIG. It is a side view of a rigidity variable drive device. FIG. 9 is an explanatory diagram of the operation of the variable stiffness drive apparatus according to the fifth embodiment of the present invention. FIG. 10 is a diagram illustrating characteristics of the variable stiffness drive apparatus according to the fifth embodiment of the present invention. In addition, about the structure similar to the said 1st Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 8, the variable stiffness drive apparatus 1000 includes a translational stiffness variable mechanism 100 and a motor 850 that is an electromagnetic motor and a rotary motor as a drive source that generates a drive force transmitted to the output arm 8. I have.

  A ball screw 851 is fixedly disposed inside the solid cam 2 of the variable stiffness mechanism 100. A screw 852 is connected to the output shaft of the motor 850. As the screw 852 rotates about the axis G, the ball screw 851 moves linearly in the direction of the axis G. Therefore, the three-dimensional cam 2 as the other member is driven in the translational direction (the direction indicated by the arrow X in FIG. 8) as the screw 852 rotates.

  The fixed portion 7 a of the ultrasonic motor 7 is fixed to the linear guide plate 109, and the drive output portion 7 b is fixed to the solid cam 2. The solid cam 2 is rotationally driven around the axis G by the ultrasonic motor 7 supported by the linear guide plate 109. The linear guide bearing 110 supported by the linear guide plate 109 is supported by a connecting member 9c serving as a linear guide shaft so as to be able to translate in the direction of arrow X in FIG.

  That is, a unit (hereinafter referred to as “linear guide unit”) in which the solid cam 2, the ultrasonic motor 7, and the linear guide plate 109 are integrated by rotating the screw 852 with the driving force of the motor 850 is indicated by an arrow X direction in FIG. It is the structure which can be driven in translation. Thus, the motor 850 drives the three-dimensional cam 2 in the direction of the arrow X in which the output arm 8 can be displaced, and the cam followers 3A and 3B urged by the compression coil springs 4A and 4B and the cam follower support shafts 6A and 6B. A driving force is output from the output arm 8 via

  FIG. 9A shows a reference position L0 in which the linear guide unit is sufficiently extended in the X + direction in FIG. 9, and represents a state F = 0 in which no external force is applied to the output end 8a. The position of the output end 8a is assumed to be Xa. FIG. 9B shows a state in which an external force F1 has acted on the output end 8a from the state of FIG. 9A. At this time, the position of the output end 8a is displaced from Xa to Xm (arrow + direction in FIG. 9). FIG. 9C shows a state where the linear guide unit has been pulled and moved from the state of FIG. 9A by a distance Lm (X-direction in FIG. 9). This represents a state F = 0 in which no external force is applied to the output end 8a. FIG. 9D shows a state in which the cam followers 3A and 3B have moved the distance Xm when the external force F1 is applied to the output end 8a from the state of FIG. 9C.

  As shown in FIG. 9B, when an external force of + F1 acts on the output end 8a, when the cam followers 3A and 3B move along the cam surface 2a of the three-dimensional cam 2, the compression coil springs 4A and 4B are compressed, and the spring Stop where it balances with the force. At this time, the rigidity of the output end 8a of the output arm 8 is F1, and is displaced from the reference position Xa by Xm.

  FIG. 9C and FIG. 9D show a state where the linear guide unit is towing and moving by a distance Lm. When an external force of + F1 acts on the output end 8a of the output arm 8, the cam followers 3A and 3B move along the cam surface 2a of the three-dimensional cam 2, and the compression coil springs 4A and 4B are compressed and stop where they balance with the spring force. . Therefore, the displacement is Xm as in FIG.

  FIG. 10 is a diagram showing the characteristics of the variable stiffness drive apparatus 1000 according to the fifth embodiment of the present invention, and shows the relationship of the component force F in the horizontal direction (relative movement direction) with respect to the displacement X of the output end 8a. .

  The relationship between the states in FIG. 9 will be described with reference to FIG. 10A. When the external force is applied from the position Xa where the external force is 0, the force of the horizontal component increases smoothly at the output end 8a. And it stops at F1 where the force balances. The displacement at this time is Xm, and the stop position is Xa + Xm. When the linear guide unit is pulled by a distance Lm by the motor 850, the characteristic curve k1 of the output F with respect to the displacement X becomes the distance Lm as it is and the parallel movement along the horizontal axis. That is, it shows that the horizontal component force of the variable stiffness drive apparatus 1000 can be moved to a position of zero.

  FIG. 10B is a diagram showing characteristics in which the rigidity of the output end 8a is changed at the position Xa. k1 represents low rigidity, point curve k2 represents intermediate rigidity, and point line k3 represents high rigidity. k1 is the rigidity when the cam followers 3A and 3B are positioned at the maximum width of the cam groove of the three-dimensional cam 2. k2 is the rigidity when the cam followers 3A and 3B are positioned at the intermediate width of the cam groove of the three-dimensional cam 2. k3 is the rigidity when the cam followers 3A and 3B are positioned at the minimum width of the cam groove of the three-dimensional cam 2.

  The solid cam 2 is rotated by the ultrasonic motor 7 to change the rigidity characteristic from k1 to k3. The cam surface 2a of the three-dimensional cam 2 has a smoothly connected cam shape, and the cam followers 3A and 3B biased by the cam surface 2a of the three-dimensional cam 2 can perform a continuous rolling operation. Therefore, the rigidity characteristic is continuously variable.

  Thus, since the variable stiffness drive apparatus 1000 of the fifth embodiment includes the stiffness variable mechanism 100, the position where the horizontal component force is zero can be moved. Furthermore, since the rigidity characteristics can be freely changed continuously, the rigidity can be changed very widely. Therefore, it is possible to achieve both a very soft operation and a high-speed and high-precision operation with respect to the target position.

[Sixth Embodiment]
Next, a variable stiffness drive apparatus according to a sixth embodiment of the present invention will be described. FIG. 11 is a sectional view showing a variable stiffness drive apparatus according to the sixth embodiment of the present invention. In addition, about the structure similar to the said 2nd Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 11, the variable stiffness drive device 2000 includes a rotary stiffness variable mechanism 200 and a motor 850 that is an electromagnetic motor and a rotary motor as a drive source that generates a drive force transmitted to the output gear 212. I have.

  A cylindrical casing 209 of the variable stiffness mechanism 200 is fixed to the output shaft of the motor 850. The housing 209 is driven to rotate about the axis M by a motor 850.

  The driving force of the motor 850 is transmitted to the output gear 212 via the cam followers 203A and 203B and the three-dimensional cam 202. That is, the cam followers 203A and 203B, which are the other members, are driven in the rotation direction when the housing 209 rotates. Thus, the motor 850 drives the cam followers 203A and 203B in the rotational direction in which the output gear 212 can be displaced via the housing 209, the cam follower drive ring 208, and the cam follower support shafts 206A and 206B. The motor 850 outputs driving force from the output gear 212 via the three-dimensional cam 202.

  As described above, the variable stiffness drive apparatus 2000 according to the sixth embodiment is the same as the fifth embodiment except that the drive direction of the variable stiffness drive apparatus 1000 including the translational stiffness variable mechanism is different. Therefore, in the sixth embodiment, the rigidity characteristic can be freely changed continuously and freely, so that the rigidity can be changed very widely. Therefore, it is possible to achieve both a very soft operation and a high-speed and high-precision operation with respect to the target position.

[Seventh Embodiment]
Next, a variable stiffness drive apparatus according to a seventh embodiment of the present invention will be described. FIG. 12 is a sectional view showing a variable stiffness drive apparatus according to the seventh embodiment of the present invention. In addition, about the structure similar to the said 5th Embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 12, the stiffness variable drive device 3000 includes a translational stiffness variable mechanism 300 and a motor 850 that is an electromagnetic motor and a rotary motor as a drive source that generates a drive force transmitted to the output arm 8. I have.

  The stiffness variable mechanism 300 includes a linear guide clutch 900 and a screw brake 901 as moving means instead of the ultrasonic motor 7 that is the moving means of the fifth embodiment. That is, the three-dimensional cam 2 can be driven by the connection and release operations by the linear guide clutch 900 and the screw brake 901.

  The linear guide clutch 900 includes a coil portion 900 a fixed to the linear guide plate 109 and a rotating portion 900 b fixed to one end of the three-dimensional cam 2. When the coil unit 900a is energized to excite the coil unit 900a, a magnetic flux is generated between the coil unit 900a and the rotating unit 900b, the rotating unit 900b is attracted to the coil unit 900a, and the rotating unit 900b is connected to the coil unit 900a. It becomes. When the coil unit 900a is not energized, the rotating unit 900b is rotatable about the axis G with respect to the coil unit 900a. Thus, the solid cam 2 is integrated with the linear guide plate 109 when the coil portion 900a is energized.

  The screw brake 901 includes a brake coil portion 901a fixed to the other end of the three-dimensional cam 2, and a brake plate portion 901b supported by the brake coil portion 901a and disposed to face the screw 852. When the brake coil portion 901a is energized to excite the brake coil portion 901a, a magnetic flux is generated, the brake plate portion 901b is pressed against the screw 852, and is integrated with the screw 852 by a frictional force. Thereby, the solid cam 2 is integrated with the screw 852 when the brake coil portion 901a is energized.

  Therefore, when the coil portion 900a is in an energized state and the brake coil portion 901a is in a non-energized state, the solid cam 2 and the linear guide plate 109 are integrated, and the solid cam 2 is rotated as shown in FIG. Moves in the direction of arrow X.

  When the coil portion 900a is in a non-energized state and the brake coil portion 901a is in an energized state, the solid cam 2 and the screw 852 are integrated, and the solid cam 2 is centered on the axis G by the rotation of the screw 852. Rotate to.

  As described above, the linear guide clutch 900 and the screw brake 901 transmit the driving force from the motor 850 (external) to the three-dimensional cam 2 when the coil portion 900a is in the non-energized state and the brake coil portion 901a is in the energized state. To do. As a result, the cam followers 3A and 3B are relative to each other in the orthogonal direction perpendicular to the direction along the track on the cam surface 2a of the cam followers 3A and 3B that move with the displacement of the output arm 8 on the cam surface 2a. Move to.

  The above operation will be described in detail. When the solid cam 2 is driven in translation, the linear guide clutch 900 connects the solid cam 2 and the linear guide plate 109 when the coil portion 900a is energized. On the other hand, the screw brake 901 releases the brake of the screw brake 901 when the brake coil portion 901a is in a non-energized state. By rotating the motor 850 in this state, the screw 852 rotates and the ball screw 851 moves in translation, so that the three-dimensional cam 2 moves in translation.

  When the solid cam 2 is rotationally driven (normal direction drive), the linear guide clutch 900 releases the connection between the solid cam 2 and the linear guide plate 109 when the coil portion 900a is not energized. On the other hand, the screw brake 901 connects the solid cam 2 and the screw 852 when the brake coil portion 901a is energized. By rotating the motor 850 in this state, the screw 852 and the three-dimensional cam 2 rotate integrally.

  Thus, by switching the driving of the motor 850 by the linear guide clutch 900 and the screw brake 901, the solid cam 2 can be rotated around the axis G, and the trajectories of the cam followers 3A and 3B can be changed. .

  Note that the variable stiffness drive apparatus 2000 including the rotary stiffness variable mechanism shown in FIG. 11 can similarly use a linear guide clutch or a screw brake instead of the ultrasonic motor 207. Accordingly, the cam followers 203A and 203B can be freely moved in the direction of the axis M, and the trajectories of the cam followers 203A and 203B can be changed.

  Therefore, since a dedicated cam follower drive motor such as the ultrasonic motors 7 and 207 is not required, a small and lightweight variable stiffness drive device is possible.

[Eighth Embodiment]
Next, a joint drive device according to an eighth embodiment of the present invention will be described. FIG. 13 is an explanatory diagram of a joint drive device according to an eighth embodiment of the present invention. FIG. 13A is a side view of the joint driving device. FIG. 13B is a diagram showing the relationship between the generated force of the variable stiffness drive device and the joint angle.

  The joint drive device according to the eighth embodiment shown in FIG. 13A 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 body 50. . One end of the link 51 is fixed to the base body 50. 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. More specifically, a pulley 53 is fixed to one end of the link 52 so as to be rotatable about a shaft 54 fixed to the other end of the link 51.

In the eighth embodiment, the robot arm 5000 includes two variable stiffness drive devices 1000 ₁ and 1000 ₂ that drive the joint J and have the same configuration as the variable stiffness drive device of the fifth embodiment. These variable stiffness drive devices 1000 ₁ and 1000 ₂ are fixed to the link 51. The two variable stiffness drive apparatuses 1000 ₁ and 1000 ₂ have the same characteristics and are antagonistically arranged at the joint J. That is, the two stiffness variable drive devices 1000 ₁ and 1000 ₂ are arranged on both sides of the link 51.

Output ends 8a ₁ and 8a ₂ of the variable stiffness drive apparatuses 1000 ₁ and 1000 ₂ are coupled to the pulley 53 by wires 55 ₁ and 55 ₂ . The variable stiffness drive devices 1000 ₁ and 1000 ₂ are controlled in contraction force by respective control circuits (not shown), and drive the link 52.

FIG. 13B shows the relationship between the joint angle θ of the joint J and the generated force F of the variable stiffness drive devices 1000 ₁ and 1000 ₂ . AL ₀ is a reference position L ₀ where the linear guide unit of the variable stiffness drive apparatus 1000 ₁ is sufficiently extended, and shows a characteristic in a state F = 0 in which there is no external force applied to the output end 8a ₁ . AL ₁ and AL _m are characteristics in a state where the linear guide unit portion is pulled by distances L ₁ and L _m from the reference position. The characteristics BL ₀ , BL ₁ , BL _{m of the} variable stiffness drive device 1000 _{2 that} are antagonistically arranged also represent the same state as the variable stiffness drive device 1000 ₁ .

For example, when the force acting on the joint J is controlled to fs in both the arrow + direction and the − direction at the position of the joint angle θ = 0 °, the variable stiffness drive device 1000 ₁ has the characteristic AL _m , and the variable stiffness drive device 1000 ₂ has The characteristic BL _m may be selected. At this time, the force acting on the joint J can be controlled to ± fs.

Further, when the force acting on the joint J is driven at f1 in the arrow + direction at the position of the joint angle θ = 0 °, the variable stiffness drive device 1000 ₁ has the characteristic AL ₁ and the variable stiffness drive device 1000 ₂ has the characteristic BL. _What is necessary is _just to select _m . Generation force at this time, the rigid variable drive apparatus 1000 ₁ fc, the rigidity variable drive apparatus 1000 ₂ becomes fs, the difference is the driving torque f1.

Conversely, when the force acting on the joint is driven at −f1 in the arrow-direction at the position of the joint rotation angle θ = 0 °, the variable stiffness drive device 1000 ₁ has the characteristic AL _m , and the variable stiffness drive device 1000 ₂ has The characteristic BL ₁ may be selected. Force generated at this time rigid variable drive apparatus 1000 ₁ fs, and the so generated force of the rigid variable drive apparatus 1000 ₂ becomes fc, the difference is the driving torque -f1.

Accordingly, from the characteristics of FIG. 13B, the joint stiffness is the sum of the generated forces of the _two variable stiffness drive apparatuses 1000 ₁ and 1000 ₂ , and the drive force (torque) is the two variable stiffness drive apparatuses 1000 ₁ and 1000 _2. It can be seen that this is the difference in the generation force.

By combining the characteristics AL ₀ , AL ₁ , AL _m , BL ₀ , BL ₁ , BL _m of the two stiffness variable drive devices 1000 ₁ , 1000 ₂ antagonized in this way, the desired drive torque and joint stiffness can be obtained. It can be controlled independently.

Furthermore, the variable stiffness drive devices 1000 ₁ and 1000 ₂ include the stiffness variable mechanism 100 of the first embodiment. Therefore, a large drive torque can be obtained by changing the stiffness characteristics of one or both of the antagonized variable stiffness drive devices 1000 ₁ and 1000 ₂ using the cam followers 3A and 3B, and a large joint stiffness can be obtained from a small joint stiffness. Is possible.

[Ninth Embodiment]
Next, a joint drive device according to a ninth embodiment of the present invention will be described. FIG. 14 is a side view showing a joint drive device according to the ninth embodiment of the present invention.

  The joint driving apparatus of the ninth embodiment shown in FIG. 14 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 body 50. One end of the link 51 is fixed to the base body 50. 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. More specifically, a pulley 53 is fixed to one end of the link 52 so as to be rotatable about a shaft 54 fixed to the other end of the link 51.

  In the ninth embodiment, the robot arm 6000 includes one variable stiffness driving apparatus 1000 that drives the joint J and has the same configuration as the variable stiffness driving apparatus of the fifth embodiment. The variable stiffness drive device 1000 is fixed to the link 51. The output end 8 a of the variable stiffness drive apparatus 1000 is rotatably coupled to the pulley 53. Thus, the variable stiffness drive device 1000 can drive both towing and pushing. The variable stiffness drive apparatus 1000 has a driving force controlled by a control circuit (not shown) and drives the link 52.

  Even in the above configuration, the target drive torque and the joint stiffness can be controlled independently by moving the joint angle of 0 joint stiffness to an arbitrary position and further varying the stiffness of the stiffness variable mechanism. Accordingly, since the joint rigidity can be freely set regardless of the joint angle from the low rigidity to the high rigidity, a dynamic operation becomes possible.

  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 eighth and ninth embodiments, the case where the variable stiffness drive apparatus is the variable stiffness drive apparatus 1000 of the fifth embodiment has been described. However, the variable stiffness drive apparatus 2000 of the sixth embodiment may be used. .

  In the eighth and ninth embodiments, the case where the stiffness variable drive device is a robot arm has been described. However, the present invention is not limited to this, and the power assist device and other robots such as a legged robot and a caregiver are not limited thereto. It can also be applied to industrial robots.

  Moreover, although the said 1st-9th embodiment demonstrated the case where an ultrasonic motor was used as a moving means, you may use an electromagnetic motor and a solenoid.

  Moreover, in the said 1st-9th embodiment, although the surface formed in the concave groove shape was made into the cam surface in the solid cam, the surface formed in the convex shape is good also as a cam surface.

2 ... Solid cam, 2a ... Cam surface, 3A, 3B ... Cam follower, 4A, 4B ... Compression coil spring (elastic member), 7 ... Ultrasonic motor (moving means), 8 ... Output arm (displacement member), 100 ... Rigidity Variable mechanism, 1000 ... variable stiffness drive, 5000 ... robot arm (joint drive)

Claims (6)

A displacement member displaceable by an external force;
A three-dimensional cam having a cam surface;
A cam follower that moves relative to the three-dimensional cam while contacting the cam surface in accordance with the displacement of the displacement member;
An elastic member that urges the cam follower to the cam surface and imparts rigidity to the displacement member according to an inclination angle of the cam surface;
Moving means for relatively moving the cam follower on the cam surface in a direction orthogonal to a direction along a track on the cam surface of the cam follower that moves in accordance with the displacement of the displacement member; Prepared,
The variable rigidity mechanism according to claim 1, wherein the cam surface is formed so that a curved shape of a cross section in the track varies depending on a position in the orthogonal direction.   The said cam surface has a part in which the amount of elastic deformation of the said elastic member becomes constant when the said cam follower moves on the said cam surface with the displacement of the said displacement member. Variable stiffness mechanism. One member of the three-dimensional cam and the cam follower is supported by the displacement member so as to be displaced together with the displacement member,
The said moving means drives the other member among the said solid cam and the said cam follower so that the said cam follower may move relatively to the said orthogonal | vertical direction with respect to the said cam surface. Variable stiffness mechanism. One member of the three-dimensional cam and the cam follower is supported by the displacement member so as to be displaced together with the displacement member,
The moving means transmits an external driving force to the other member of the three-dimensional cam and the cam follower so that the cam follower moves relative to the cam surface in the orthogonal direction. The rigidity variable mechanism according to claim 1 or 2. The rigidity variable mechanism according to any one of claims 1 to 4,
And a drive source for generating a drive force to be transmitted to the displacement member. The first link,
A second link articulated to the first link;
A joint drive device comprising: the variable stiffness drive device according to claim 5 that drives the joint.

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