JP2019076992A - Joint structure and bipedal walking robot having joint structure in coxa - Google Patents

Abstract

To provide a joint structure that is able to avoid an increase of the size of a joint part, able to extend a movable range of the joint part, and able to achieve high output of a rotating operation of a joint shaft.SOLUTION: A joint structure 10 comprises a first member 14, a second member 18, and a joint shaft 16, and a motor arrangement area S of approximately triangular shape is formed in the first member 14. In the motor arrangement area S, a first drive wheel 26 provided on an output shaft 24a of a first motor 24 and a second wheel 30 provided on an output shaft 28a of a second motor 28, and a steering wheel 32 are arranged. The first drive wheel 26, the second drive wheel 30 and the steering wheel 32 are arranged such that a shape f formed by connecting their axes is substantially similar to an approximate triangle. An endless member 36 is stretched over the first drive wheel 26, the second drive wheel 30, the steering wheel 32 and a to-be-driven wheel 34 such that one of the first drive wheel 26, the second drive wheel 30 and the steering wheel 32 is located outside the endless member 36.SELECTED DRAWING: Figure 1

Description

  According to the present invention, a joint shaft rotatably connecting the first member, the second member, the first member and the second member, and the first member and the second member around the axis of the joint shaft via the reduction gear. The present invention relates to a joint structure including a relatively rotating motor. The present invention also relates to a biped walking robot including the joint structure in a hip joint.

  The joint structure for driving a link of a robot includes a servo-driven motor, a reduction gear, and a transmission including, for example, a belt and a pulley for transmitting the power of the motor to the reduction gear, and is attached to the output shaft of the reduction gear There is one that rotates the link. By the way, in recent years, high output of joint axis movement is required. As a general method to realize it, it is conceivable to increase the size of the motor, but in most cases there is a limit on the dimensions of the motor that can be mounted on the robot, and high power output of joint axis is easily achieved. It is difficult to As one of the different methods, it is conceivable to drive the link by a plurality of motors, but on the other hand, the robot is also required to be miniaturized, and the enlargement of the joint and the movable range of the joint are It is not easy to install multiple motors and their associated transmissions while avoiding narrowing.

  Patent Document 1 discloses, in a biped robot, a waist plate, a swing link that performs an external or internal rotation motion around a vertical with respect to the hip plate, an opening and closing link that performs an opening and closing motion with respect to the swing link, and an opening and closing link. The opening and closing link and the fore and aft moving link are provided as a cantilever supporting structure with respect to the turning link, and a portion of the turning link that interferes with the opening and closing link and the turning link at the opening and closing of the opening and closing link A hip joint structure is disclosed in which a wide movement range of the opening and closing link is secured by forming the ring into a substantially triangular shape. However, Patent Document 1 does not consider arranging a plurality of motors for the opening and closing movement of the opening and closing link.

  In Patent Document 2, one motor driver drives at least two or more brushed DC motors having the same characteristic and wired in series, and the output of each motor is transmitted to the rotation shaft by the transmission mechanism, and one free. Drives have been proposed that produce a degree of movement. However, in Patent Document 2, for example, a plurality of motors are disposed in a relatively wide space, such as the thighs of a biped walking robot, and a space in which the motors can be disposed as in the turning link in Patent Document 1. It is not considered about the placement in the place where is limited.

Japanese Patent Application Laid-Open No. 2003-089080 JP, 2013-150511, A

  The present invention solves the above-mentioned problems of the prior art, avoids enlargement of the joint, widens the movable range of the joint, and can achieve high output of joint motion and a joint structure for the hip joint It aims at providing a equipped biped robot.

  The present invention comprises a first member, a second member, and a joint shaft rotatably connecting the first member and the second member, wherein the first member is moved closer to the joint shaft. A joint structure in which a substantially triangular motor arrangement area is formed by approaching one side surface to the other side surface on the opposite side, which are arranged in the motor arrangement area to achieve the above object, Provided on a first motor and a second motor that relatively rotate the first member and the second member around the axis of the joint shaft via a reduction gear, and an output shaft of the first motor The first drive wheel, the second drive wheel provided on the output shaft of the second motor, the rolling wheels disposed in the motor arrangement area, and the input portion of the reduction gear A driven wheel, the first drive wheel, the second drive wheel, and A driving wheel and an endless member mounted on the driven wheel to transmit the driving force from the first driving wheel and the second driving wheel to the driven wheel; and the first driving wheel The second drive wheel and the rolling wheel are arranged such that a shape connecting their axes substantially corresponds to the substantially triangular motor arrangement region, and the endless member is the first member. The first drive wheel, the second drive wheel, the rolling wheel, and the driven wheel such that one of the driving wheel, the second driving wheel, and the rolling wheel is positioned outside the endless member. It is hung on Here, "having substantially the same shape as the substantially triangular motor arrangement area" refers to three sides of a triangle connecting the axis of the first drive wheel, the axis of the second drive wheel, and the axis of the rolling wheel. Is parallel to one side of the first member or at an angle difference of ± 20 degrees or less with respect to the one side, and the other one of the three sides is parallel to the other side of the first member Or it shall mean making an angle difference of ± 20 degrees or less to the other side.

  In the joint structure according to the present invention, the endless member is stretched between the first drive wheel, the second drive wheel, the rolling wheel, and the driven wheel using both surfaces thereof. It is preferable to transmit the driving force.

  Further, in the joint structure according to the present invention, the second member has a structure supported in a cantilever manner by the first member via the joint shaft located on the side surface of the end portion on the first member side. Is preferred.

  Further, in the joint structure according to the present invention, one of the first drive wheel and the second drive wheel is disposed inside the endless member, and the other is disposed outside the endless member. Is preferred.

  Furthermore, in the joint structure of the present invention, preferably, the rolling wheel can be changed in fixed position so that the tension of the endless member can be adjusted.

  Further, in the joint structure of the present invention, it is preferable that the first motor is a master motor, and the second motor is a slave motor that performs tracking control on the first motor.

  Further, in the joint structure of the present invention, a third motor and a third drive wheel are provided instead of the rolling wheel, and the first drive wheel, the second drive wheel and the third drive are provided. The wheels are arranged such that the shape connecting their axes is substantially similar to the substantially triangular motor arrangement area, and the endless member comprises the first drive wheel, the second drive wheel, and the second drive wheel. The first drive wheel, the second drive wheel, the third drive wheel, and the driven wheel are suspended such that one of the third drive wheels is located outside the endless member. ing.

  Furthermore, in the joint structure according to the present invention, the first motor is a master motor, and the second motor and the third motor are slave motors that follow and control the first motor. Is preferred.

  Further, in order to achieve the above object, a biped walking robot according to the present invention includes the joint structure described in any one of the above in a hip joint that opens and closes a pair of legs.

  According to the joint structure of the present invention, since the first motor and the second motor are provided as drive means for relatively rotating the first member and the second member around the axis of the joint shaft, the joint operation can be performed at a high level. Output can be realized. In addition, since the first drive wheel, the second drive wheel, and the rolling wheel on which the endless member is hung are arranged in a positional relationship substantially similar to the substantially triangular motor arrangement region, the joint structure is large. It is possible to arrange two motors in a substantially triangular motor arrangement area without increasing the range of movement of the joint structure.

FIG. 1 is a front view showing a hip joint of a biped robot according to a first embodiment of the present invention, which includes the joint structure according to the first embodiment of the present invention. It is the front view which showed the operation state (state after abduction motion) of the hip joint of FIG. It is the front view which showed the state which adjusted the tension of the belt as an endless member in the hip joint of FIG. It is a front view showing a hip joint of a biped robot according to a second embodiment of the present invention, which comprises the joint structure according to the second embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, FIG. 1 is a view showing a hip joint in a biped robot according to the first embodiment of the present invention, to which the joint structure according to the first embodiment of the present invention is applied. In FIG. 1, a symbol Z is a line segment common to a frontal plane which is a plane bisecting the body of the biped robot forward and backward, and a sagittal plane which is a plane bisecting the body of the biped robot horizontally Indicates a certain median axis.

  As shown in FIG. 1, the hip joint structure 10 in the biped robot according to the embodiment is configured as a joint having three degrees of freedom capable of performing internal and external rotation motions, adduction and abduction motions, and bending and extension motions. Pivot link 14 as a first member that causes the leg 12 to rotate about its axis (yaw axis) z1 and causes the leg 12 to rotate about its axis (roll axis as a joint axis (roll (roll) Axis) open / close link 18 as a second member that brings about the introversion / abduction movement of the leg 12 by rotating about the x1 axis, and bending / extension of the leg 12 by rotating about the axis line (pitch axis) y1 of the longitudinal movement axis It has a back and forth movement link 20 that brings about movement.

  The pivot link 14 is rotatably held by the body 22 around the axis z1 via the pivot shaft and a bearing that supports the pivot link. The internal and external rotation movement of the swing link 14 with respect to the body 22 transmits the rotation of a servo-driven motor disposed in the body 22 to a reduction gear such as a harmonic reduction gear via a transmission including, for example, a belt and a pulley. (Not shown).

  The plate-like portion of the swing link 14 on the side of the opening and closing shaft 16 in the space between the body 22 and the opening and closing shaft 16 is positioned outside as viewed from the opening and closing shaft 16 as viewed from the front The side surface 14a is formed in a substantially triangular shape approaching the opposite inner side surface (side surface on the median axis side) 14b. The substantially triangular plate-like portion of the swing link 14 is a motor disposition area S described later. In the illustrated example, the inner side surface 14b is constituted by a plane parallel to the median axis Z, the outer side surface 14a is constituted by an inclined surface approaching the median axis Z as approaching the opening / closing axis 16, and the upper side 14c is at the median axis Z It is formed along a direction (pitch axis direction) orthogonal to the direction. Therefore, this triangle is a right triangle whose hypotenuse is the outer side surface 14a and its extension 14a '.

  The open / close link 18 is rotatably (rockably) coupled to the lower end portion (lower portion of the motor arrangement area S) of the swing link 14 via an open / close shaft 16 and a bearing (not shown) supporting the same. The pivot link 14 is supported in a cantilever manner by being formed outwardly therefrom in the direction of the pitch axis (the direction away from the median axis Z). Further, the tip end portion of the open / close link 18 is disposed in a nested state in the back and forth movement link 20. The nested structure of the open / close link 18 and the back and forth movement link 20 may be replaced with a method in which a part of the open and close link 18 is inserted into the back and forth movement link 20, or vice versa.

  As described above, the open / close link 18 is cantilevered with respect to the swing link 14 at a position near the median axis Z, and the outer side surface 14a of the open / close shaft 16 peripheral portion of the swing link 14 is notched in a slope shape. Of the opening / closing link 18 when the opening / closing link 18 is rotated while avoiding interference between the opening / closing link 18 and the swing link 20 and the swing link 14 while the opening / closing link 18 is rotated. The abduction movement range can be expanded. FIG. 2 shows a state where the leg 12 is abducted until the outer side surface 14 a of the swing link 14 and the upper surface of the open / close link 18 and the front-rear movement link 20 become substantially parallel.

  By the way, when the outer side surface 14 a of the swing link 14 is notched in a slope shape, the motor arrangement region S for arranging the motor for driving the open / close link 18 and the transmission device is limited to a substantially triangular shape. When the open / close link 18 is driven by two or more motors in view of high output of rotation / abduction motion, the installation space for two or more motors and two or more transmission devices corresponding to each motor I can not secure enough.

  Further, while avoiding the interference between the opening and closing link 18 and the front and rear movement link 20 and the swing link 14 when the opening and closing link 18 is rotated, the joint movable range of the leg 12 in the abduction motion is broadened. When the movable range is made wide, the angle formed by the extension line 14a 'of the outer side surface 14a and the inner side surface 14b becomes an acute angle, and the endless belt 36 tends to protrude outward from the outer side surface 14a of the turning link 14. Installation space can not be secured enough.

  Therefore, in this embodiment, two motors are arranged in the motor arrangement area S, but the motor arrangement is limited by sharing the transmission for transmitting the driving force of the two motors and devising the arrangement of the motor and the transmission. In the area S, two motors and their associated transmissions can be arranged. Specifically, in the motor arrangement area (plate-like portion) S, a servo-controlled first motor 24 provided with a first drive wheel 26 on its output shaft 24a, and a second motor 24 on its output shaft 28a And a rolling wheel 32 rotatably mounted on the swing link 14. A first driving wheel 26, a second driving wheel are provided. An endless belt 36 as an endless member is provided on the wheel 30 and the rolling wheel 32 and the driven wheel 34 fixed to the input portion (input shaft) of the reduction gear (not shown) having an axis x1 common to the opening / closing shaft 16 It is suspended. The first and second motors 24 and 28 are disposed on the back side of the substantially triangular plate-like portion, and their output shafts 24 a and 28 a pass through the plate-like portion, and the first drive wheel 26 is disposed. The second drive wheel 30 and the rolling wheel 32 are respectively disposed on the front side of the plate-like portion.

  The endless belt 36 is stretched between the first drive wheel 26, the second drive wheel 30, the rolling wheel 32, and the driven wheel 34 using both sides of the endless belt 36 to transmit the driving force. . In the endless belt 36, the first drive wheel 26, the rolling wheels 32, and the driven wheel 34 are positioned inside the endless belt 36, and the remaining second drive wheels 30 are positioned outside the endless belt 36. , The second drive wheel 30, the rolling wheel 32, and the driven wheel 34. The base 38 supporting the rolling wheel 32 so as to freely rotate is fixed by inserting a fastener 42 such as a screw into the long hole-like fixing hole 40 formed in the plate-like portion of the pivot link 14. The tension of the endless belt 36 can be adjusted by changing the position of the fastener 42 with respect to 40 and adjusting the fixed position of the rolling wheel 32.

  The first drive wheel 26, the second drive wheel 30, and the rolling wheel 32 are arranged such that the shape f connecting their axes is substantially similar to the substantially triangular motor arrangement area S. In the illustrated example, the first drive wheel 26, the second drive wheel 30, and the rolling wheels 32 are disposed in two upper and lower stages, and the first drive wheel 26 is disposed on the outer side in the pitch axis direction of the upper stage (upper stage outer side) The rolling wheel 32 is disposed on the inner side in the pitch axis direction (upper stage inner side), and the second driving wheel 30 is disposed on the lower stage, and a line segment f1 connecting the axial line of the rolling wheel 32 and the axial line of the second driving wheel 30 A line connecting the axis of the first drive wheel 26 and the axis of the second drive wheel 30 while forming an angle difference of ± 20 degrees or less parallel to the inner side surface 14b of the swing link 14 or less The position f2 is parallel to the inclined outer side surface 14a of the swing link 14 or at an angular difference of ± 20 degrees or less with respect to the outer side surface 14a. The first drive wheel 26, the second drive wheel 30, and the rolling wheel 32 may be disposed at any position as long as the shape f connecting their axes is substantially similar to the substantially triangular motor arrangement region S. For example, the first drive wheel 26 may be disposed in the upper stage inner side or lower stage, the second drive wheel 30 may be disposed in the upper stage inner side or upper stage outer side, and the rolling wheel 32 may be disposed in the upper stage outer side or lower stage, respectively. . In any case, the endless belt 36 is provided from the outside in the pitch axis direction so that the first drive wheel 26, the second drive wheel 30, and the rolling wheel 32 located on the lower side are located on the outer side of the endless belt 36 It is preferable that the belt be suspended, which can prevent the endless belt 36 from protruding outward from the outer side surface 14 a of the pivot link 14.

  In the illustrated example, a double-toothed timing belt is used for the endless belt 36, a toothed pulley is used for the first drive wheel 26, the second drive wheel 30, and the driven wheel 34, and a gear is used for the rolling wheel 32. However, this is only an example, and any driving force can be transmitted to the driven wheel 34 as long as the driving force of the first driving wheel 26 and the second driving wheel 30 can be transmitted, for example, the first driving wheel 26, the second The driving wheel 30, the rolling wheel 32, and the driven wheel 34 may use a pulley having no teeth and may use an endless belt having no teeth as the endless member, or the first driving wheel 26, the first A sprocket may be used as the drive wheel 30, the rolling wheel 32, and the driven wheel 34, and a roller chain may be used as the endless member.

  A reduction gear (not shown) whose input part (input shaft) is fixed to the driven wheel 34 is, for example, a harmonic reduction gear, and its output part (output shaft) is fixed to the open / close link 18 and endless belt 36 The rotational power of the first motor 24 and the second motor 28 input via the second motor 28 is transmitted to the open / close link 18 with a predetermined reduction ratio.

  In an advantageous embodiment of the invention, the first motor 24 is a master motor and the second motor 28 is a slave motor controlled to follow the first motor 24. For example, the first motor 24 is driven by angle control or speed control by a control device (not shown) such as a CPU (central processing unit) and the second motor 28 is driven by torque control, and power applied to the endless belt 36 is The second motor 28 follows and rotates with respect to the rotation of the first motor 24 so as to be in the same direction, whereby any target angle or target speed can be obtained at the driven wheel 34 or the open / close shaft 16 Thus, by determining the driving forces of the first motor 24 and the second motor 28, the rotations of the first motor 24 and the second motor 28 can be synchronized with each other.

  The back and forth movement of the front and rear movement link 20 with respect to the opening and closing link 18, that is, the bending and extension movement of the leg 12 is the transmission of a servo driven motor disposed on the front and back movement link 20. Transmission to a reduction gear such as a harmonic reduction gear (not shown).

  Using the hip joint structure 10 configured in this manner, the control device (not shown) performs the first motor 24 via the motor driver (not shown) in order to perform the adduction / abduction movement of the leg 12 of the biped robot. The second motor 28 is rotationally driven in the direction of the arrow in FIG. The rotational power of the first motor 24 and the second motor 28 is transmitted from the first drive wheel 26 and the second drive wheel 30 to the driven wheel 34 via the endless belt 36 and connected to the driven wheel 34 The reducer decelerates the input rotational power with a predetermined reduction ratio and outputs it to the output unit, and the open / close link 18 connected to the output unit Is rotated about the axis x1 of the open / close shaft 16. At this time, since the outer side surface 14a of the portion around the opening / closing shaft 16 of the turning link 14 is notched like a slope, the interference between the turning link 14 and the opening / closing link 18 and the front / rear movement link 20 is avoided. Thus, it is also possible to make the open / close link 18 abducted parallel to the outer side surface 14 a of the pivot link 14.

  Further, in the hip joint structure 10, in the motor arrangement area S, the first motor 24 provided with the first drive wheel 26 on the output shaft 24a thereof and the second drive wheel 30 provided on the output shaft 28a thereof A second motor 28, rolling wheels 32 freely rotatably attached to the turning link 14, a first driving wheel 26, a second driving wheel 30, a rolling wheel 32, and an input portion of a reduction gear. The endless belt 36 is stretched around the driven wheel 34 fixed to the first drive wheel 26, the second drive wheel 30, and the rolling wheel 32, and their axes are connected. The arrangement is made so as to be substantially similar to the motor arrangement area S of the shape, so that it is possible to achieve both the realization of the wide joint movable range and the increase in output by the expansion of the introversion / abduction movement range of the leg 12.

  Further, in the hip joint structure 10, the open / close link 18 is cantilevered on the pivot link 14 via the open / close shaft 16. Therefore, the open / close shaft 16 can be disposed close to the median axis Z, It can be configured compactly.

  Furthermore, in the hip joint structure 10, since the first motor 24 is a master motor and the second motor 28 is a slave motor that performs tracking control to the first motor 24, the open / close link 18 is operated in cooperation. The first and second motors 24 and 28 can be synchronized with each other, and the open / close link 18 can be smoothly rolled in and out.

  It is the front view which showed the hip joint structure 10 of the biped robot of 2nd embodiment of this invention provided with the joint structure of 2nd embodiment of this invention. The same elements as those of the previous embodiment are denoted by the same reference numerals, and the description will be appropriately omitted.

  In the hip joint structure 10 of this embodiment, as shown in FIG. 4, a third motor 44 and a third drive wheel 46 fixed to its output shaft 44a are used in place of the rolling wheels 32 in the previous embodiment. Is equipped. In an advantageous aspect of this embodiment, the first motor 24 is a master motor, and the second motor 28 and the third motor 44 are slave motors controlled to follow the first motor 24. For example, the first motor 24 is driven by angle control or speed control by a control device (not shown) such as a CPU (central processing unit), and the second motor 28 and the third motor 44 are driven by torque control. The second motor 28 and the third motor 44 follow the rotation of the first motor 24 so that the power applied to the belt 36 is in the same direction, whereby the driven wheel 34 or the open / close shaft is rotated. The first motor 24, the second motor 24, and the second motor 28 are determined by determining the driving forces of the first motor 24, the second motor 28, and the third motor 44 so that any target angle or target speed can be obtained. , And the rotation of the third motor 44 can be synchronized with each other.

  According to the hip joint structure 10 of this embodiment, the third motor 44 and the third drive wheel 46 are provided instead of the rolling wheels 32, and the first motor 24 is used as a master motor, and the second motor 28 and the Since the third motor 44 is a slave motor that follows and controls the first motor 24, the first motor 24, the second motor 28, and the third motor 44 that move the open / close link 18 in cooperation with each other are used. The opening / closing link 18 can be smoothly rotated inward or outward by synchronizing with each other, and joint shaft operation can be further enhanced compared to the case where only the first motor 24 and the second motor 28 are provided. .

  Although the present invention has been described above based on the illustrated example, the present invention is not limited to the embodiment, and can be modified within the scope of the claims. For example, in the above description, the joint structure is a biped robot The joint structure of the present invention is applicable to other joints such as the arm joint of a robot.

  According to the present invention, at least two motors can be arranged in the substantially triangular motor arrangement region without enlarging the joint structure, and the movable range can be expanded, and the output of the rotational motion of the joint shaft can be increased. It is possible to provide a biped robot equipped with a joint structure that can be achieved and the joint structure in a hip joint.

DESCRIPTION OF SYMBOLS 10 hip joint structure 12 legs 14 turning link 14a outer side 14b inner side 16 opening-closing axis 18 opening-closing link 20 front-rear moving link 22 body 24 1st motor 24a output shaft 26 1st driving wheel 28 2nd motor 28a output shaft 30 2 drive wheels 32 rolling wheels 34 driven wheels 36 endless belts 38 base 40 fixing holes 42 fasteners 44 third motor 44a output shaft 46 third drive wheel S motor arrangement area

Claims (9)

A first member, a second member, and a joint shaft rotatably connecting the first member and the second member, wherein one side face of the first member approaches the joint shaft. A joint structure in which a substantially triangular motor arrangement area is formed by approaching the other side of the opposite side,
A first motor and a second motor disposed respectively in the motor disposition area and relatively rotating the first member and the second member around the axis of the joint shaft via a reduction gear;
A first drive wheel provided on an output shaft of the first motor;
A second drive wheel provided on an output shaft of the second motor;
Rolling wheels disposed in the motor disposition area;
A driven wheel connected to the input of the reduction gear;
The driving force from the first drive wheel and the second drive wheel is applied to the driven wheel while being hung on the first drive wheel, the second drive wheel, the rolling wheel, and the driven wheel. And an endless member for transmitting
The first drive wheel, the second drive wheel, and the rolling wheel are arranged such that a shape connecting their axes substantially corresponds to the substantially triangular motor arrangement area.
The endless drive member is configured such that the first drive wheel, the second drive wheel, and the second drive wheel are positioned such that one of the first drive wheel, the second drive wheel, and the rolling wheel is positioned outside the endless member. A joint structure characterized in that the wheel, the rolling wheel and the driven wheel are stretched.   The endless member is suspended between the first drive wheel, the second drive wheel, the rolling wheel and the driven wheel using both sides thereof to transmit a driving force. The joint structure according to Item 1.   The second member has a structure supported in a cantilever manner by the first member via the joint shaft located on the side surface of the end portion on the first member side. Joint structure described.   2. One of the first drive wheel and the second drive wheel is disposed inside the endless member, and the other is disposed outside the endless member. Joint structure according to any one of the preceding three.   The joint structure according to any one of claims 1 to 4, wherein a fixed position of the rolling wheel is changeable so as to adjust a tension of the endless member.   The first motor according to any one of claims 1 to 5, wherein the first motor is a master motor, and the second motor is a slave motor that performs control to follow the first motor. Joint structure. A third motor and a third drive wheel are provided instead of the rolling wheel.
The first drive wheel, the second drive wheel, and the third drive wheel are arranged such that the shape connecting their axes is substantially similar to the substantially triangular motor arrangement region.
The endless member is a member such that the first drive wheel, the second drive wheel, and the third drive wheel are positioned outside the endless member, The joint structure according to any one of claims 1 to 6, wherein the joint structure is hung on two drive wheels, the third drive wheel, and the driven wheel.   The joint according to claim 7, wherein the first motor is a master motor, and the second motor and the third motor are slave motors that follow and control the first motor. Construction.   A biped walking robot comprising the joint structure according to any one of claims 1 to 8 in a hip joint that opens and closes a pair of legs.

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