JP4442464B2 - Articulated arm mechanism - Google Patents

Description

  The present invention relates to an articulated arm mechanism that requires arm tip rigidity control in a posture in which various loads are supported.

  A rear end of a first arm that is generally formed as an “articulated arm mechanism” is rotatably connected to a base portion that is a base point of operation, and the front end of the first arm is There is a mechanism that is rotatably connected to the rear end of the second arm formed in a long shape (see, for example, Patent Document 1). Such a mechanism is used in devices such as robots, manipulators, and power shovels, for example.

  FIG. 12 is a diagram illustrating a first configuration example of a conventional articulated arm mechanism. In the example shown in FIG. 12, the number of joints is only two, but there may be three or more. Further, in the figure, white circles indicate rotatable parts.

  As shown in FIG. 12, the multi-joint arm mechanism 1 of the first configuration example has a rear end of the first arm 10 rotatably connected to the base 5 via the joint portion 20, and the first arm 10 is rotatably connected to the tip of an actuator 30 such as a hydraulic cylinder that expands and contracts, and the tip of the first arm 10 is rotatable to the rear end of the second arm 40 via a joint 50. It is connected. In such an articulated arm mechanism 1, the first arm 10 rotates around the joint portion 20 as the actuator 30 expands and contracts. The rear end of the actuator 30 is rotatably connected to the base 5.

  In the multi-joint arm mechanism 1, the rear end of the second arm 40 is rotatably connected to the first arm 10 via the joint 50, and the approximate center of the second arm 40 is a hydraulic cylinder or the like. It is rotatably connected to the tip of an actuator 60 that expands and contracts. In such an articulated arm mechanism 1, the second arm 40 rotates around the joint portion 50 as the actuator 60 expands and contracts. The distal end of the second arm 40 is a free end, and the actuator 30 or 60 expands or contracts to move the position, or to apply a force to the outside, or to apply a force (load) from the outside. ), A restoring force (rigidity) is generated with respect to an externally applied force. Further, the rear end of the actuator 60 is rotatably connected to the joint portion 50.

  In the articulated arm mechanism 1 shown in FIG. 12, independent control of the position, force, and rigidity of the tip of the second arm 40 with respect to the rear end of the first arm 10 is extremely difficult in terms of control theory. The position, force, and rigidity are controlled approximately with respect to the tip of the second arm 40. However, the articulated arm mechanism 1 has a problem that it is difficult to perform accurate and quick positioning control when a large load is applied to the tip of the second arm 40 which is a free end.

  Therefore, the multi-joint arm mechanism 1 has an actuator 30 and 60 with an excessive output compared to the load so that accurate and quick positioning control can be easily performed even when a large load is applied to the tip of the second arm 40. In addition, the power source (not shown) for driving the actuators 30 and 60 has an excessive capacity. As a result, the multi-joint arm mechanism 1 can easily perform accurate and quick positioning control even when a large load is applied to the tip of the second arm 40 which is a free end. However, the articulated arm mechanism 1 configured as described above has an excessive output and braking force, and the power supply has an excessive capacity. Therefore, the structure is increased in size and the cost is increased. There has been a problem that the operability is lowered.

  Therefore, a second example configuration shown in FIG. 13 is provided as an articulated arm mechanism that solves the problem of the first example configuration.

  FIG. 13 is a diagram illustrating a second configuration example of a conventional articulated arm mechanism. In the figure, white circles indicate rotatable parts.

  As shown in FIG. 13, in the multi-joint arm mechanism 2 of the second configuration example, an actuator 70 is added to the components of the multi-joint arm mechanism 1 of the first configuration example. The actuator 70 has a distal end rotatably connected to the second arm 40 and a rear end rotatably connected to the base 5, and antagonizes the rotational operation cooperatively performed by the actuator 30 and the actuator 60. Rotating operation is performed. Such an articulated arm mechanism 2 can separately control the position, force and rigidity of the tip of the second arm 40 by simultaneously operating the three actuators 30, 60 and 70. Therefore, the articulated arm mechanism 2 can limit the outputs of the actuators 30 and 60, the braking force, and the capacity of the power source to a required amount. As a result, the multi-joint arm 2 is accurate even when a large load is applied to the tip of the second arm 40 while solving the problems that the structure is enlarged, the cost is increased, and the operability is lowered. In addition, quick positioning control can be easily performed.

However, the articulated arm 2 requires an additional actuator 70. Further, in order to drive the additional actuator 70, it is necessary to increase the capacity of the power source. Therefore, the articulated arm mechanism 2 has a problem that the weight increases and the cost increases.
Japanese Unexamined Patent Publication No. Hei 8-19973 (paragraphs 1 to 31 and FIGS. 1 to 6)

  In the conventional first configuration example, there is a problem that it is difficult to perform accurate and quick positioning control when a large load is applied to the free end. As the size of the device increases, the cost increases and the operability decreases.

  Further, the second configuration example, which is supposed to solve the problem of the first configuration example, has a problem that the weight increases and the cost increases.

  Therefore, conventionally, there are problems that it is difficult to perform accurate and quick positioning control when a large load is applied to the free end, a problem that the structure is enlarged, a problem that the cost is increased, and operability. The problem of lowering and the problem of increasing weight could not be solved at the same time.

  In order to solve the above-described problem, an articulated arm mechanism according to a first invention includes a base portion serving as a base point of operation, a first arm rotatably connected to the base portion, a base portion, and a first portion. A first joint that connects the first arm, a first actuator that rotates the first arm around the first joint, and a second arm that is rotatably connected to the first arm And a second joint that connects the first arm and the second arm, and a second actuator that rotates the second arm around the second joint. The first joint portion includes a first elastic force transmission portion fixed to the base portion, and the second joint portion includes a second elastic force transmission portion fixed to the second arm, The first elastic force transmitting portion and the second elastic force transmitting portion have a first locking portion having elasticity and a second locking portion having elasticity on both sides of the rotation plane across the first arm. And is locked by.

  In the multi-joint arm mechanism according to the first invention, the two locking portions simultaneously apply an elastic force to the elastic force transmitting portions of the two joint portions.

  In the multi-joint arm mechanism according to the first invention, compared to the conventional second configuration example, one of the actuators is replaced with a locking portion having elasticity, so the number of actuators is the same as that of the conventional second configuration. It is possible to easily control the position, force, and rigidity of the tip of the second arm, which is the free end, while reducing the number of examples (that is, the same as the conventional first configuration example).

  Therefore, the articulated arm mechanism according to the first invention has a problem that it is difficult to perform accurate and quick positioning control when a large load is applied to the free end, a problem that the structure is enlarged, and a cost. Simultaneously solves the problem of rising soaring, the problem of reduced operability, and the problem of increased weight.

  Moreover, the multi-joint arm mechanism according to the first invention acts simultaneously so that the elastic forces of the two locking portions are automatically harmonized with the elastic force transmitting portions of the two joint portions. . Therefore, the articulated arm mechanism according to the first invention can maintain a constant force and rigidity by the elastic force of the two locking portions even for a large input or a fast input that the actuator cannot respond to, In particular, it is possible to easily realize a quick operation such as flexibly capturing falling objects and flying objects.

  In addition, the multi-joint arm mechanism according to the first aspect of the present invention is configured by two simple locking members, such as a tension coil spring, a torsion bar, and a torsion coil spring, which are simple and inexpensive members that do not require power. can do. Therefore, the articulated arm mechanism according to the first invention can be configured with a simple member that does not require power and at a low cost.

  The multi-joint arm mechanism according to the second invention includes, in addition to the components of the multi-joint arm mechanism according to the first invention, a third arm rotatably connected to the second arm, A third joint that connects the arm and the third arm; and a third actuator that rotates the third arm about the third joint. In addition to the second elastic force transmission unit, the second joint unit further includes a third elastic force transmission unit fixed to the first arm, and the third joint unit includes the third arm. A third elastic force transmitting portion fixed to the third elastic force transmitting portion, and the third elastic force transmitting portion and the fourth elastic force transmitting portion are elastic on both sides of the rotation plane across the second arm. And the fourth locking portion having elasticity.

  In the multi-joint arm mechanism according to the second invention, the four locking portions simultaneously apply elastic force to the elastic force transmitting portions of the three joint portions.

  The multi-joint arm mechanism according to the second invention can be used, for example, for a leg portion of a biped robot. In this case, in each component of the multi-joint arm mechanism according to the second invention, the base portion functions as a trunk, the first arm functions as a thigh, the first joint portion functions as a hip joint, The arm functions as a shin, the second joint functions as a knee joint, the third arm functions as a foot, and the third joint functions as an ankle joint.

  In the multi-joint arm mechanism according to the second invention, the third and fourth elastic force transmission portions act in the same manner as the first and second elastic force transmission portions in the multi-joint arm mechanism according to the first invention. . Therefore, the multi-joint arm mechanism according to the second aspect of the invention has a configuration having three joint parts, and can realize the same operation as the multi-joint arm mechanism according to the first aspect of the invention having two joint parts.

  The articulated arm mechanism according to the present invention has a problem that accurate and quick positioning control is difficult when a large load is applied to the free end, a problem that the structure becomes large, and a cost increase. The problem, the problem that the operability is lowered, and the problem that the weight is increased can be solved simultaneously.

  This invention has a problem that it is difficult to perform accurate and quick positioning control when a large load is applied to the free end, a problem that the structure is enlarged, a problem that the cost is increased, and a decrease in operability. An object of the present invention is to provide an articulated arm mechanism that simultaneously solves the problem of increasing the weight and the problem of increasing weight. In order to achieve such an object, in the present invention, the articulated arm mechanism is configured as follows. In other words, the first joint portion connecting the base portion and the first arm includes the first elastic force transmission portion fixed to the base portion, and the first joint connecting the first arm and the second arm. The two joint portions include a second elastic force transmission portion fixed to the second arm, and the first elastic force transmission portion and the second elastic force transmission portion rotate with the first arm interposed therebetween. The multi-joint arm mechanism is configured so as to be locked on both sides of the plane by the first locking portion having elasticity and the second locking portion having elasticity.

  Embodiments of the present invention will be described below with reference to the drawings. Each drawing merely schematically shows the shape, size, and arrangement relationship of each component to the extent that the present invention can be understood. Therefore, the present invention is not limited to the illustrated example. Moreover, in each figure, the same code | symbol is attached | subjected about the common component and the same component, and those overlapping description is abbreviate | omitted.

<Configuration of articulated arm mechanism according to Embodiment 1>
The configuration of the articulated arm mechanism according to the first embodiment will be described below. Here, a two-joint arm mechanism having two joint parts will be described as an example.

  FIG. 1 is a side view illustrating the configuration of the multi-joint arm mechanism according to the first embodiment, and FIG. 2 is a top view illustrating the configuration of the multi-joint arm mechanism according to the first embodiment. 1 and 2 schematically show each component, and in particular, a base arm 106 and first and second arms 110 and 140, which will be described later, only show their center lines. . In FIG. 1, the inner diameters of teeth of gears 124, 132, 154, and 162, which will be described later, are indicated by dashed-dotted circles, and the outer diameters of teeth are indicated by solid-line circles.

  As shown in FIGS. 1 and 2, the multi-joint arm mechanism (hereinafter also referred to as a “two-joint arm mechanism”) 100 according to the first embodiment rotates to a base portion 104 that is a base point of operation and to the base portion 104. First arm 110 that can be connected, first joint portion 120 that connects base portion 104 and first arm 110, first motor 130 that rotates first arm 110, and first A second arm 140 that is rotatably connected to the arm 110, a second joint 150 that connects the first arm 110 and the second arm 140, and a second that rotates the second arm 140. Motor 160.

  The base unit 104 includes, for example, an apparatus main body such as a robot, a manipulator, and a power shovel, or a base 105 that is a fixing target such as a wall or a floor, and a base arm 106 that is a long member protruding from the base 105. Here, it is assumed that the base 105 includes a control unit 109 that controls the driving of the first and second motors 130 and 160. The control unit 109 is a program that changes the rigidity of the first and second motors 130 and 160 that rotate each joint unit according to a rotation angle from the equilibrium point of each joint unit (hereinafter referred to as a joint angle). It is a stored CPU. The base unit 104 rotates the first and second arms with an arbitrary point as the origin in the space coordinates. Here, the origin in the spatial coordinates of the rotational motion of the first and second arms 110 and 140 is the tip of the base arm 106 (that is, the center position of the rotation of the first joint portion 120).

  The first arm 110 is a long member, and its rear end is fixed to a first pulley 126 described later. The first arm 110 rotates around a first joint shaft 122 described later as the first motor 130 rotates. The first arm 110 is provided with a projection 112 at the rear end for regulating the rotation angle.

  The first joint part 120 includes a first joint shaft 122, a gear 124, a first pulley 126 fixed to the base arm 106 of the base part 104, and a first joint part 120 (specifically, First measuring means 128 for measuring the joint angle of the gear 124) (that is, the rotation angle of the first arm 110). The first joint shaft 122, the gear 124, and the first pulley 126 are respectively disposed with the tip of the base arm 106 as a common shaft. However, the first joint shaft 122 and the first pulley 126 are fixed to the tip of the base arm 106 and do not rotate with respect to the base arm 106 even if the first motor 130 rotates. On the other hand, the gear 124 is rotatably arranged at the tip of the base arm 106, and rotates with respect to the base arm 106 when the first motor 130 rotates. The gear 124 is fixed to the first arm 110 and serves as a first power transmission unit that rotates together with the first arm 110 by the first motor 130 about the first joint shaft 122. The first measuring means 128 is constituted by, for example, a rotary potentiometer fixed to the base arm 106. Alternatively, the first measuring unit 128 may be constituted by, for example, a slit plate fixed to the gear 124 and a rotary encoder fixed to the base arm 106. The first measuring unit 128 outputs the measured joint angle of the first joint unit 120 (that is, the rotation angle of the first arm 110) to the control unit 109 via a wiring (not shown).

  The first motor 130 is a first actuator that rotates the first arm 110. The first motor 130 is fixed to the base arm 106 of the base portion 104, and a gear 132 that meshes with the gear 124 of the first joint portion 120 is attached. The first motor 130 generates a rotational force under the control of the control unit 109 and rotates the first arm 110 fixed to the gear 124 via the gear 132. The first motor 130 is fixed to the base arm 106 at a position where the outer periphery of the gear 132 of the first motor 130 is in contact with the center line of the base arm 106 and the gear 132 as shown in FIG. Is a position that meshes with the gear 124 of the first joint 120.

  The second arm 140 is a long member, and its rear end is fixed to a second pulley 156 described later. The second arm 140 rotates together with the second pulley 156 around the second joint shaft 152 described later as the second motor 160 rotates. The second arm 140 is provided with a projection 142 at the rear end for regulating the rotation angle. In the first embodiment, the tip of the second arm 140 is a free end.

  The second joint 150 includes a second joint shaft 152, a gear 154, a second pulley 156 fixed to the second arm 140, and a second joint 150 (specifically, the gear 154). ) Joint angle (that is, the rotation angle of the second arm 140). The second joint shaft 152, the gear 154, and the second pulley 156 are respectively disposed with the tip of the first arm 110 as a common axis. However, the second joint shaft 152 is fixed to the tip of the first arm 110, and the gear 154 and the second pulley 156 are rotatably arranged at the tip of the first arm 110. The gear 154 is fixed to the second arm 140 and serves as a second power transmission unit that rotates together with the second arm 140 by the second motor 160 about the second joint shaft 152. The second pulley 156 is fixed to the second arm 140 together with the gear 154. When the gear 154 is rotated by the second motor 160, the second pulley 156 rotates together with the second arm 140 about the second joint shaft 152. To do. The second measuring means 158 is constituted by, for example, a rotary potentiometer fixed to the first arm 110. Alternatively, the second measuring unit 158 may be constituted by, for example, a slit plate fixed to the gear 154 and a rotary encoder fixed to the first arm 110. The second measuring unit 158 outputs the measured joint angle of the second joint unit 150 (that is, the rotation angle of the second arm 140) to the control unit 109 via a wiring (not shown). The control unit 109 determines the rigidity of the first and second motors 130 and 160 based on the joint angles of the first and second joint units 120 and 150 output from the first and second measuring units 128 and 158. To change.

  The second motor 160 is a second actuator that rotates the second arm 140. The second motor 160 is fixed to the first arm 110 and is attached with a gear 162 that meshes with the gear 154 of the second joint portion 150. The second motor 160 generates rotational force under the control of the control unit 109 and rotates the second pulley 156 and the second arm 140 fixed to the gear 154 via the gear 162. The position where the second motor 160 is fixed to the first arm 110 is such that the outer periphery of the gear 162 of the second motor 160 is in contact with the center line of the first arm 110 as shown by a right-angle symbol in FIG. In addition, the gear 162 is a position where the gear 162 meshes with the gear 154 of the second joint portion 150.

  The first pulley 126 of the first joint portion 120 and the second pulley 156 of the second joint portion 150 are elastic with the first locking portion 210 having elasticity on both sides of the first arm 110. It is locked by the second locking portion 220. The first pulley 126 serves as a first elastic force transmission unit that transmits the elastic force of the first locking part 210 and the elastic force of the second locking part 220 to the first joint shaft 122. Yes. The second pulley 156 serves as a second elastic force transmission unit that transmits the elastic force of the first locking part 210 and the elastic force of the second locking part 220 to the second joint shaft 152. Yes.

  The first locking portion 210 is formed as a configuration including, for example, a first tension coil spring 212 that is an elastic body and two wires 214 and 216. The wire 214 of the first locking portion 210 has a tip fixed to a hook at the rear end of the first tension coil spring 212 and a rear end wound around the outer periphery of the first pulley 126 and fixed. The first tension coil spring 212 has a front end hook fixed to the rear end of the wire 216 and a rear end hook fixed to the front end of the wire 214. The tip of the wire 216 is wound around the outer periphery of the second pulley 156 and fixed, and the rear end is fixed to the hook at the tip of the first tension coil spring 212.

  Moreover, the 2nd latching | locking part 220 is formed as a structure provided with the 2nd tension coil spring 222 which is an elastic body, and the two wires 224,226, for example. The front end of the wire 224 of the second locking portion 220 is fixed to the hook at the rear end of the second tension coil spring 222, and the rear end is opposite to the rear end of the wire 214 on the outer periphery of the first pulley 126. It is wound around and fixed. The second tension coil spring 222 has a front end hook fixed to the rear end of the wire 226 and a rear end hook fixed to the front end of the wire 224. The tip of the wire 226 is fixed by being wound around the outer periphery of the second pulley 156 in the direction opposite to the tip of the wire 216, and the rear end is fixed to the hook at the tip of the second tension coil spring 222.

  The first and second tension coil springs 212 and 222 have the same elastic modulus here. The first and second tension coil springs 212 and 222 are in a state where the first and second arms 110 and 140 are not rotating (that is, the tips of the first and second arms 110 and 140 are the same). In a state of facing the direction), it is in a balanced state. At this time, both the first and second tension coil springs 212 and 222 are extended by the same length. Hereinafter, the lengths of the first and second tension coil springs 212 and 222 in this state are referred to as natural lengths of the first and second tension coil springs 212 and 222.

  The wires 214, 216, 224, and 226 are always pulled by the elastic force of the first and second tension coil springs 212 and 222, which are elastic bodies. Therefore, the axes of the wires 214, 216, 224 and 226 always exist in the tangential direction of the first or second pulleys 126 and 156 within the operating range of the first and second arms 110 and 140.

  In addition, the elastic force (torque) of the first and second tension coil springs 212 and 222 is determined by using the radius of the first pulley 126 or the radius of the second pulley 156 as a moment arm. The product torque acts on the first and second joints 120 and 150.

  Further, the amount of deflection of the first and second tension coil springs 212 and 222 is the length obtained by multiplying the displacement angle from the equilibrium point of the joint angle of the first joint portion 120 by the moment arm, and the second joint. The sum of the lengths obtained by multiplying the displacement angle from the equilibrium point of the joint angle of the portion 150 by the moment arm.

  Here, the tension coil spring is used as the elastic body of the first and second locking portions 210 and 220, but the same effect can be obtained even if a torsion bar or a torsion coil spring is used. Further, although the first and second pulleys 126 and 156 are used as means for transmitting the elastic force to the joint shaft, other configurations may be used.

  1 and 2 show a state where the first and second joint portions 120 and 150 are stopped at the home position (that is, a state where the first and second motors 130 and 160 are not driven). Show.

<Operation of Articulated Arm Mechanism According to Embodiment 1>
The operation of the articulated arm mechanism according to the first embodiment will be described below.

  3 to 5 are diagrams each illustrating an operation example of the articulated arm mechanism according to the first embodiment.

  3 shows a state in which the first and second joint portions 120 and 150 of the two-joint arm mechanism 100 are rotated by an arbitrary angle from the home position (see FIGS. 1 and 2) (that is, the first and second motors). 130 and 160 are driven).

  FIG. 4 is obtained by adding two-dimensional spatial coordinates including the X axis and the Y axis to FIG. 4 shows FIG. 3 rotated 180 degrees so that the X axis and the Y axis are drawn in the positive direction from the origin of the spatial coordinates (that is, the tip of the base arm 106 of the base unit 104).

In FIG. 4, r ₁ indicates the radius of the first pulley 126, and r ₂ indicates the radius of the second pulley 156. L ₁ indicates the arm length of the first arm 110, and L ₂ indicates the arm length of the second arm 140. Θ ₁ indicates the joint angle of the first joint portion 120, and θ ₂ indicates the joint angle of the second joint portion 150. The coordinates (x, y) indicate the position of the free end (that is, the tip of the second arm 140).

  FIG. 5 shows the coordinates and vector of the position of the tip of the second arm 140 which is a free end.

  In general, the speed of the free end of the multi-joint arm mechanism (here, the tip of the second arm 140 of the two-joint arm mechanism 100) and the speed of the joint angle, or the first and second joint shafts 122 and 152 work. It is known that torque (hereinafter referred to as joint shaft torque) and free end force are related by a Jacobian matrix. The joint shaft torque and the free end force can be obtained based on several mathematical formulas described below.

  In the two-joint arm mechanism 100, the coordinates (x, y) of the free end are expressed by Equation 1 below.

Here, focusing on the fact that θ ₁ and θ ₂ are independent variables, the relationship between the small displacement of the free end (Δx, Δy) ^T and the small displacement of the joint angle (Δθ ₁ , Δθ ₂ ) ^T is as follows: It can be expressed as Equation 2 below. Note that “T” is a symbol indicating a transposed matrix. The transposed matrix is converted to an (m, n) type matrix A = (aij) having aij as an (i, j) component, and converted to an (n, m) type having an aji as an (i, j) component. It is a matrix. Here, the small displacements (Δx, Δy) ^T of the free end and the minute displacements (Δθ ₁ , Δθ ₂ ) ^T of the joint angle are components of 2 rows and 1 column.

  Here, the following Expression 3 is a Jacobian matrix.

On the other hand, according to the law of conservation of energy, the work done by the small displacement of the joint angle and the joint axis torque is equal to the work done by the small displacement of the free end and the force of the free end, so any (Δθ ₁ , Δθ ₂ ) ^T On the other hand, the following expression 4 holds.

Here, if the Jacobian matrix is represented as J, Equation 4 becomes Equation 5 below. Therefore, the following formula 6 is established. In the two-joint arm mechanism 100, the Jacobian matrix J can also be expressed as the following Expression 7, where the coordinates of the second joint portion 150 are (x ₁ , y ₁ ) ^T.

  Here, when the free end force is obtained from the joint shaft torque based on the above equation 6, the free end force is expressed by the following equation 8 and further by the following equation 9.

  Here, if the position of the free end is represented by a vector, the result is as shown in FIG. In FIG. 5, the vector a indicates a vector from the origin (that is, the first rotation axis 122) of the free end (that is, the tip of the second arm 140), and the vector b indicates the second arm 140. A vector from the second joint axis 152 at the tip of the first arm 110 is shown, and a vector c shows a vector from the origin of the tip of the first arm 110.

  Further, as described above, the elastic force (torque) of the first and second tension coil springs 212 and 222 is determined by using the radius of the first pulley 126 or the radius of the second pulley 156 as a moment arm. The torque that is the product of the moment arm acts on the first and second joint portions 120 and 150.

  Further, as described above, the amount of deflection of the first and second tension coil springs 212 and 222 is the length obtained by multiplying the displacement angle from the equilibrium point of the joint angle of the first joint portion 120 by the moment arm, and This is the sum of the length obtained by multiplying the displacement angle from the equilibrium point of the joint angle of the second joint portion 150 by the moment arm.

Therefore, in the two-joint arm mechanism 100, the torques generated by the two actuators (first and second motors 130 and 160) are denoted as τ _a1 and τ _a2 , respectively, and the first and second locking portions 210 and 220 Two elastic bodies (first and second tension coil springs 212, 222) are both represented by κ, and two elastic force transmission parts (first and second pulleys 126) to which the two elastic bodies are connected. , 156) are assumed to be γ ₁ and γ ₂ , respectively, and joint angles at which the elastic body has a natural length are θ ₁₀ and θ ₂₀ , respectively, and displacement angles from the joint angles θ ₁₀ and θ ₂₀ are δ ₁ , Let δ ₂ . Then, the joint shaft torques τ ₁ and τ ₂ can be expressed as the following Expression 11, and the output of the free end can be expressed as the following Expression 12.

  Here, the component of the following formula 13 is a component that does not depend on the posture change (that is, the change of the joint angle), and the component of the following formula 14 is a component that depends on the posture change.

  By distinguishing between these components that do not depend on posture changes and components that depend on posture changes, the force at the free end can be controlled by the torque that the actuator acts on the joint axis. The response to the displacement of the joint angle (that is, the rigidity of the free end) can be controlled by the moment arm.

  Therefore, in the multi-joint arm mechanism 100 according to the first embodiment, compared to the conventional second configuration example, one of the actuators is replaced with a latching portion having elasticity. The position, force, and rigidity of the distal end of the second arm 140, which is a free end, can be easily controlled while reducing the configuration of the second arm 140 (ie, the same as the first configuration example of the related art).

  Therefore, the articulated arm mechanism 100 according to the first embodiment has a problem that it is difficult to perform accurate and quick positioning control when a large load is applied to the free end, a problem that the structure is enlarged, and a cost. Simultaneously solves the problem of rising soaring, the problem of reduced operability, and the problem of increased weight.

<Control of Articulated Arm Mechanism According to Embodiment 1>
The control of the articulated arm mechanism according to the first embodiment will be described below.

  The control unit 109 of the multi-joint arm mechanism 100 uses the joint angles measured by the first and second measuring units 128 and 158 to calculate the first and second joint units 120, The first and second motors 130 and 160 that are the first and second actuators are controlled so that the joint shaft torque of 150 changes.

Here, (τ _a1 , τ _a2 ) ^T is a joint shaft torque calculated as a control amount of the first and second motors 130 and 160 as the first and second actuators. Further, (τ _u1 , τ _u2 ) ^T is an arbitrary joint axis torque, and is a component that does not depend on posture change (that is, change in joint angle). Moreover, the following formula | equation 16 is arbitrary elastic coefficients. Further, (δ ₁ , δ ₂ ) ^T is a joint angle. The following Expression 17 is a component that depends on the posture change.

  The output at the free end is expressed by the following formula 18, and the force of the following formula 19 and the rigidity of the following formula 20 are generated at the free end.

Both force and rigidity have coefficients that can be set arbitrarily. Therefore, the force and rigidity of the free end can be controlled based on the blocks shown in FIG. FIG. 6 is a diagram illustrating a control block of the articulated arm mechanism according to the first embodiment. In FIG. 6, G ₂ (s) is the open loop characteristic of the actuator. Note that the open loop characteristic means, for example, how the rotational speed of the motor rises when the moment of inertia of the motor is changed stepwise depending on the load and angle. G (s) is a controller characteristic, and H (s) is a delay compensator characteristic.

  Since the articulated arm mechanism 100 according to the first embodiment has an elastic body that simultaneously acts on two joint portions, it has a certain elasticity even for a large input or an angular displacement input that the actuator cannot respond to. There are features.

  The multi-joint arm mechanism 100 according to the first embodiment can arbitrarily control the rigidity of the free end by changing the torque of the actuator acting on the joint axis in accordance with the joint angular displacement. For this reason, for example, it is possible to realize the optimum rigidity for the operation of an apparatus such as an arm type robot.

  Further, the multi-joint arm mechanism 100 according to the first embodiment simultaneously acts so that the elastic forces of the two locking portions are automatically harmonized with the elastic force transmission portions of the two joint portions. . Therefore, the articulated arm mechanism 100 according to the first embodiment can maintain a constant force and rigidity by the elastic force of the two locking portions even for a large input or a fast input that the actuator cannot respond to, In particular, it is possible to easily realize a quick operation such as flexibly capturing falling objects and flying objects.

  In addition, the multi-joint arm mechanism 100 according to the first embodiment includes two locking portions that are simple and inexpensive members that do not require power, such as a tension coil spring, a torsion bar, and a torsion coil spring. can do. Therefore, the articulated arm mechanism according to the first embodiment can be configured at a low cost with a simple member that does not require power.

<Configuration of Articulated Arm Mechanism According to Second Embodiment>
The configuration of the articulated arm mechanism according to the second embodiment will be described below.

  The multi-joint arm mechanism according to the second embodiment is configured to have three joint portions by further adding a pair of arms and joint portions to the multi-joint arm mechanism 100 according to the first embodiment. Here, a case where the articulated arm mechanism having such a configuration is applied to a leg of a robot will be described as an example.

  FIG. 7 is a side view illustrating the configuration of the multi-joint arm mechanism according to the second embodiment. FIG. 8 is a front view illustrating the configuration of the multi-joint arm mechanism according to the second embodiment. 7 and 8 schematically show each component. In particular, the base arm 106, the first and second arms 110 and 140, and the third arm 170 described later are the centers. Only lines are shown. Further, in FIG. 7, the inner diameters of the teeth of the gears 124, 132, 154, 162 and the gears 184, 192 to be described later are indicated by a one-dot chain line, and the outer diameters of the teeth are indicated by a solid circle.

  As shown in FIGS. 7 and 8, the multi-joint arm mechanism (hereinafter sometimes referred to as a three-joint arm mechanism) 600 according to the second embodiment is similar to the multi-joint arm mechanism 100 according to the first embodiment. In addition, the second joint portion 150 has a double structure (see FIG. 8) provided with a third pulley 157, a third arm 170, a third joint portion 180, and a third motor. 190 and third and fourth locking portions 230 and 240.

  The second joint portion 150 includes a third pulley fixed to the first arm 110 in addition to the second joint shaft 152, the gear 154, the second pulley 156, and the second measuring means 158. 157. The third pulley 157 is arranged together with the second joint shaft 152, the gear 154, and the second pulley 156 with the tip of the first arm 110 as a common axis. The radius of the third pulley 157 is preferably the same radius as the second pulley 156 so that the control unit 109 can easily control the radius.

  The third arm 170 is a long member formed in an L shape, and its rear end is fixed to a fourth pulley 186 described later. The third arm 170 rotates together with the fourth pulley 186 about a third joint shaft 182 described later as the third motor 190 rotates. The third arm 170 is provided with a protrusion 172 at the rear end for regulating the rotation angle. In the second embodiment, the tip end of the third arm 170 is a free end.

  The third joint portion 180 includes a third joint shaft 182, a gear 184, a fourth pulley 186 fixed to the third arm 170, and a third joint portion 180 (specifically, a gear 184). ) Joint angle (that is, the rotation angle of the third arm 170). The third joint shaft 182, the gear 184, and the fourth pulley 186 are respectively disposed with the tip of the second arm 140 as a common axis. However, the third joint shaft 182 is fixed to the distal end of the second arm 140, and the gear 184 and the fourth pulley 186 are rotatably disposed at the distal end of the second arm 140. The gear 184 is a third power transmission unit that is fixed to the third arm 170 and rotates together with the third arm 170 by the third motor 190 about the third joint shaft 182. The fourth pulley 186 is fixed to the third arm 170 together with the gear 184. When the gear 184 is rotated by the third motor 190, the fourth pulley 186 is rotated together with the third arm 170 about the third joint shaft 182. To do. The third measuring means 188 is constituted by, for example, a rotary potentiometer fixed to the second arm 140. Alternatively, the third measuring unit 188 may be configured by, for example, a slit plate fixed to the gear 184 and a rotary encoder fixed to the second arm 140. The third measuring unit 188 outputs the measured joint angle of the third joint unit 180 (that is, the rotation angle of the third arm 170) to the control unit 109 via a wiring (not shown). Based on the joint angles of the first, second, and third joints 120, 150, and 180 output from the first, second, and third measuring means 128, 158, and 188, the control unit 109 The rigidity of the second and third motors 130, 160, 190 is changed.

  The third motor 190 is a third actuator that rotates the third arm 170. The third motor 190 is fixed to the second arm 140 and attached with a gear 192 that meshes with the gear 184 of the third joint portion 180. The third motor 190 generates a rotational force under the control of the control unit 109, and rotates the fourth pulley 186 and the third arm 170 fixed to the gear 184 via the gear 192. The position where the third motor 190 is fixed to the second arm 140 is such that the outer periphery of the gear 192 of the third motor 190 is in contact with the center line of the second arm 140 as shown by a right-angle symbol in FIG. At the same time, the gear 192 meshes with the gear 184 of the third joint portion 180.

  The third pulley 157 of the second joint 150 and the fourth pulley 186 of the third joint 180 have elasticity with the third locking part 230 having elasticity on both sides of the second arm 140. It is locked by the fourth locking portion 240. The third pulley 157 serves as a third elastic force transmission unit that transmits the elastic force of the third locking portion 230 and the elastic force of the fourth locking portion 240 to the second joint shaft 152. Yes. The fourth pulley 186 serves as a fourth elastic force transmission unit that transmits the elastic force of the third locking portion 230 and the elastic force of the fourth locking portion 240 to the third joint shaft 182. Yes.

  The 3rd latching | locking part 230 is formed as a structure provided with the 3rd tension coil spring 232 and two wires 234 and 236 which are elastic bodies, for example. The tip of the wire 234 of the third locking portion 230 is fixed to the hook at the rear end of the third tension coil spring 232, and the rear end is wound around and fixed to the outer periphery of the third pulley 157. The third tension coil spring 232 has a front end hook fixed to the rear end of the wire 236 and a rear end hook fixed to the front end of the wire 234. The front end of the wire 236 is fixed by being wound around the outer periphery of the fourth pulley 186, and the rear end is fixed by a hook at the front end of the third tension coil spring 232.

  Moreover, the 4th latching | locking part 240 is formed as a structure provided with the 4th tension coil spring 242 which is an elastic body, and the two wires 244,246, for example. The leading end of the wire 244 of the fourth locking portion 240 is fixed to the hook at the rear end of the fourth tension coil spring 242, and the rear end is opposite to the rear end of the wire 234 on the outer periphery of the third pulley 157. It is wound around and fixed. The fourth tension coil spring 242 has a front end hook fixed to the rear end of the wire 246 and a rear end hook fixed to the front end of the wire 244. The tip of the wire 246 is fixed by being wound around the outer periphery of the fourth pulley 186 in the direction opposite to the tip of the wire 236, and the rear end is fixed by a hook at the tip of the fourth tension coil spring 242.

  The third and fourth tension coil springs 232 and 242 have the same elastic modulus here. Further, the third and fourth tension coil springs 232 and 242 are in a state where the second and third arms 140 and 170 are not rotating (that is, the tips of the second and third arms 140 and 170 are the same). In a state of facing the direction), it is in a balanced state. At this time, the third and fourth tension coil springs 232 and 242 are both extended by the same length. Hereinafter, the lengths of the third and fourth tension coil springs 232 and 242 in this state are referred to as natural lengths of the third and fourth tension coil springs 232 and 242.

  The wires 234, 236, 244 and 246 are always pulled by the elastic force of the third and fourth tension coil springs 232 and 242 which are elastic bodies. Therefore, the axes of the wires 234, 236, 244, and 246 always exist in the tangential direction of the third or fourth pulleys 157 and 186 within the operation range of the second and third arms 140 and 170.

  In addition, the elastic force (torque) of the third and fourth tension coil springs 232 and 242 is obtained by using the radius of the third pulley 157 or the radius of the fourth pulley 186 as a moment arm, and the respective elastic force and moment arm. The product torque acts on the second and third joints 150 and 180.

  Further, the amount of deflection of the third and fourth tension coil springs 232 and 242 is the length obtained by multiplying the displacement angle from the equilibrium point of the joint angle of the second joint 150 by the moment arm, and the fourth joint. The sum of the lengths obtained by multiplying the displacement angle from the equilibrium point of the joint angle of the portion 180 by the moment arm.

  Here, the tension coil spring is used as the elastic body of the third and fourth locking portions 230 and 240, but the same effect can be obtained even if a torsion bar or a torsion coil spring is used. Further, although the third and fourth pulleys 157 and 186 are used as means for transmitting the elastic force to the joint shaft, other configurations may be used.

  7 and 8 show a state where the first, second, and third joint portions 120, 150, and 180 are stopped at the home position (that is, the first, second, and third motors 130, 160). , 190 is not driven).

  Such an articulated arm mechanism 600 can be used for a leg of a robot as described above. In this case, the base portion 104 functions as a body, the first arm 110 functions as a thigh, the first joint portion 120 functions as a hip joint, and the second arm 140. The second joint 150 functions as a knee joint, the third arm 170 functions as a foot, and the third joint 180 functions as an ankle joint (Ankle). ).

  In such an articulated arm mechanism 600, the third and fourth pulleys 157 and 186, which are the third and fourth elastic force transmission units, are the first and second in the articulated arm mechanism 100 according to the first embodiment. This acts in the same manner as the first and second pulleys 126 and 156 which are the elastic force transmission portions. Therefore, the multi-joint arm mechanism 600 is configured to have three joint portions, and can realize the same operation as the multi-joint arm mechanism 100 according to the first embodiment having two joint portions.

<Operation of Articulated Arm Mechanism According to Example 2>
The operation of the articulated arm mechanism according to the second embodiment will be described below.

  FIG. 9 and FIG. 10 are diagrams illustrating an operation example of the articulated arm mechanism according to the second embodiment. Here, in FIG. 9 and FIG. 10, the same or similar components in FIG. 4 or FIG. 5 are denoted by the same reference numerals, and redundant description thereof is omitted.

  FIG. 9 shows a state in which the first, second, and third joint portions 120, 150, and 180 of the three-joint arm mechanism 600 are rotated by an arbitrary angle from the home position (see FIGS. 7 and 8). And a state in which the second and third motors 130, 160, 190 are driven).

In FIG. 9, r ₃ indicates the radius of the fourth pulley 186. Here, the radius of the third pulley 157 is r ₂ which is the same as the radius of the second pulley 156 here. L ₃ indicates the arm length of the third arm 170.

  FIG. 10 shows the coordinates of the position of the tip of the third arm 170 which is a free end.

In FIG. 10, θ ₃ indicates the joint angle of the third joint portion 180. The coordinates (x, y) indicate the position of the free end (that is, the tip of the third arm 170).

  In the three-joint arm mechanism 600, the torque acting on the first, second, and third joint shafts 122, 152, and 182 (hereinafter referred to as joint shaft torque) and the free end force are the two-joint arm according to the first embodiment. Similar to mechanism 100, they are related by a Jacobian matrix. In the three-joint arm mechanism 600, the joint shaft torque and the free end force are expressed by the following equation (21).

Here, θ is θ = θ ₁ + θ ₂ + θ ₃ .

  Further, the Jacobian matrix J is expressed as the following Expression 22 using the symbols in FIG.

  Also, the output of the free end can be expressed as Equation 23 below.

  Accordingly, since the three-joint arm mechanism 600 can define all the forces in the two-dimensional plane, the position, force and rigidity of the free end can be controlled.

  When the three-joint arm mechanism 600 is used for a leg of a robot, the potential energy changes so that the posture of the robot is in an equilibrium state according to the following principle even when a load is applied from the outside. . Therefore, the robot can easily obtain the standing stability.

  FIG. 11 shows a change in potential energy due to a change in the posture of the robot from the equilibrium point. FIG. 11 is a graph showing the relationship between the change in the posture of the robot and the change in potential energy. FIG. 11 shows the potential energy as a curved surface when the position of the hip joint (first joint 120) is displaced in the x and y directions from the equilibrium point. Here, the potential energy is disposed across the hip joint and the knee joint (first and second joint portions 120 and 150) and the knee joint and the ankle joint (second and third joint portions 150 and 180). This is the sum of the elastic energy accumulated in the first to fourth locking portions 210, 220, 230, and 240 and the potential energy of the entire robot.

  In FIG. 11, the curve is an equipotential curve showing a region of equal potential energy. The potential energy has a minimum value at the equilibrium point (0, 0). For this reason, when the posture of the robot is changed by a load applied from the outside, and the potential energy is displaced from the equilibrium point, a restoring force that returns the posture of the robot to the posture of the equilibrium point always works. Therefore, the robot can easily obtain the standing stability.

  In addition, since energy consuming elements such as frictional force and viscous resistance always exist in practice, Lyapunov stability (Lyapunov stability; a system determined by examining the positive / negative definiteness of a known Lyapunov function) Stability). Therefore, the robot can easily obtain the standing stability.

  A robot using such a three-joint arm mechanism 600 has asymptotic stability at an equilibrium point, and with respect to a certain range of disturbance (load applied from the outside), Even if the load distribution on the back side is not fed back to the control unit 109 and controlled, the standing posture can be maintained.

  As described above, if the three-joint arm mechanism 600 is applied to the leg of the robot, the stability of the standing position can be easily obtained, so that the control of the legged mobile robot can be simplified.

  Further, like the two-joint arm mechanism 100 according to the first embodiment, the three-joint arm mechanism 600 can maintain a certain elasticity even with respect to a fast movement that the actuator cannot respond to. Therefore, the stability of the jumping operation and the landing operation can be improved.

  In the second embodiment, two tension coil springs that antagonize are used for the elastic body that simultaneously acts on the articulated shaft. However, the same effect can be obtained even if a torsion bar or a torsion coil spring is used. Further, the means for transmitting the elastic force to the joint shaft is not limited to the above-described embodiment.

  The present invention can also be applied to manipulators and power shovel arms, for example.

  The present invention is not limited to the first and second embodiments described above, and various applications and modifications can be considered without departing from the gist of the present invention.

1 is a side view illustrating a configuration of a multi-joint arm mechanism according to Embodiment 1. FIG. FIG. 3 is a top view illustrating the configuration of the articulated arm mechanism according to the first embodiment. FIG. 6A is a diagram (1) illustrating an operation example of the articulated arm mechanism according to the first embodiment. FIG. 6B is a diagram (2) illustrating an operation example of the articulated arm mechanism according to the first embodiment. FIG. 6C is a diagram (3) illustrating an operation example of the articulated arm mechanism according to the first embodiment. It is a figure which shows the control block of the articulated arm mechanism which concerns on Example 1. FIG. FIG. 6 is a side view illustrating a configuration of a multi-joint arm mechanism according to a second embodiment. FIG. 6 is a front view illustrating a configuration of an articulated arm mechanism according to a second embodiment. FIG. 10A is a diagram (1) illustrating an operation example of the articulated arm mechanism according to the second embodiment. FIG. 10B is a diagram (2) illustrating an operation example of the multi-joint arm mechanism according to the second embodiment. It is a graph which shows the relationship between the change of the attitude | position of a robot, and the change of potential energy. It is a figure which shows the 1st structural example of the conventional articulated arm mechanism. It is a figure which shows the 2nd structural example of the conventional articulated arm mechanism.

Explanation of symbols

100 ... articulated arm mechanism (two-joint arm mechanism)
DESCRIPTION OF SYMBOLS 104 ... Base part 105 ... Base 106 ... Base arm 109 ... Control part 110 ... 1st arm 120 ... 1st joint part 122 ... 1st joint axis 124,132,154,162 ... Gear (power transmission part)
126 ... 1st pulley (1st elastic force transmission part)
128, 158... Measuring means 130... First motor (first actuator)
140 ... 2nd arm 150 ... 2nd joint part 152 ... 2nd joint axis 156 ... 2nd pulley (2nd elastic force transmission part)
160 ... second motor (second actuator)
210: first locking portion 212: first tension coil spring (elastic body)
214, 216, 224, 226 ... wire 220 ... second locking portion 222 ... second tension coil spring (elastic body)

Claims (11)

A base part as a base point of operation;
A first arm rotatably connected to the base portion;
A first joint that connects the base and the first arm;
A first actuator that rotates the first arm around the first joint;
A second arm rotatably connected to the first arm;
A second joint connecting the first arm and the second arm;
A second actuator for rotating the second arm around the second joint,
The first joint portion includes a first elastic force transmission portion fixed to the base portion,
The second joint unit includes a second elastic force transmission unit fixed to the second arm and rotating together with the second arm,
The first elastic force transmitting portion and the second elastic force transmitting portion have a first locking portion having elasticity and a second elastic having elasticity on both sides of the rotation plane across the first arm. It is locked by the locking part,
The second elastic force transmission portion transmits elastic forces of the first locking portion and the second locking portion to the second joint portion,
Respective elastic forces of the first locking portion and the second locking portion correspond to the first elastic force transmitting portion and the second provided in the first joint portion and the second joint portion, respectively. An articulated arm mechanism characterized in that the rigidity of the free end of the second arm is maintained by acting simultaneously on the elastic force transmitting portion so that the load automatically harmonizes. In the articulated arm mechanism according to claim 1,
The first locking portion includes an elastic body, and first and second wires engaged with the elastic body,
The second locking portion includes an elastic body, and third and fourth wires engaged with the elastic body,
The first elastic force transmission portion is constituted by a first pulley in which a first wire of the first locking portion and a third wire of the second locking portion are wound in opposite directions. ,
The second elastic force transmission part is constituted by a second pulley in which a second wire of the first locking part and a fourth wire of the second locking part are wound in opposite directions. An articulated arm mechanism. The multi-joint arm mechanism according to claim 2,
The articulated arm mechanism characterized in that each of the elastic bodies constituting the first and second locking portions is a tension coil spring. In the articulated arm mechanism according to claim 1,
The first joint portion is fixed to the first joint shaft serving as the center of rotation, the first elastic force transmission portion fixed to the base portion, and the first arm, and A first power transmission unit that rotates together with the first arm by the first actuator around a joint axis;
The second joint portion is fixed to the second joint axis serving as the center of rotation, the second elastic force transmission portion fixed to the second arm, and the second arm. A multi-joint arm mechanism comprising: a second power transmission unit that rotates together with the second arm by the second actuator about two joint axes. The articulated arm mechanism according to claim 4,
The first and second actuators are respectively constituted by first and second motors with gears attached thereto,
The first power transmission unit is configured by a gear that meshes with a gear attached to the first motor,
The multi-joint arm mechanism, wherein the second power transmission unit is configured by a gear meshing with a gear attached to the second motor. In the articulated arm mechanism according to claim 1,
Furthermore, the first joint angle measuring means for measuring the joint angle of the first joint part, the second joint angle measuring means for measuring the joint angle of the second joint part, the first and second And a controller for controlling the actuator of
Based on the following equation, the control unit may determine the first or second joint of the first and second actuators according to the joint angle measured by the first or second joint angle measuring unit. A multi-joint arm mechanism characterized by changing joint shaft torques τ _a1 and τ _a2 for rotating the shaft.

A base part as a base point of operation;
A first arm rotatably connected to the base portion;
A first joint that connects the base and the first arm;
A first actuator that rotates the first arm around the first joint;
A second arm rotatably connected to the first arm;
A second joint connecting the first arm and the second arm;
A second actuator that rotates the second arm about the second joint;
A third arm rotatably connected to the second arm;
A third joint connecting the second arm and the third arm;
A multi-joint arm mechanism comprising a third actuator for rotating the third arm around the third joint part,
The first joint portion includes a first elastic force transmission portion fixed to the base portion,
The second joint portion is fixed to the second arm and rotated together with the second arm, and the second joint portion is fixed to the first arm and rotated together with the first arm. And a third elastic force transmission part
The third joint portion includes a fourth elastic force transmission portion fixed to the third arm,
The first elastic force transmitting portion and the second elastic force transmitting portion have a first locking portion having elasticity and a second elastic having elasticity on both sides of the rotation plane across the first arm. Locked by the locking part,
The third elastic force transmitting portion and the fourth elastic force transmitting portion have a third locking portion having elasticity and a fourth elastic property on both sides of the rotation plane across the second arm. It is locked by the locking part,
The second elastic force transmission portion transmits elastic forces of the first locking portion and the second locking portion to the second joint portion,
The fourth elastic force transmitting portion transmits the elastic force of the third locking portion and the fourth locking portion to the third joint portion,
The potential energy given as the sum of the elastic energy accumulated in the first to fourth locking portions and the potential energy of the entire robot to which the multi-joint arm mechanism is attached is applied to the robot with respect to a load given from the outside. The articulated arm mechanism is characterized in that the posture of the robot changes so as to be in an equilibrium state, and the stability of the standing position is obtained . The articulated arm mechanism according to claim 7,
The first locking portion includes an elastic body, and first and second wires engaged with the elastic body,
The second locking portion includes an elastic body, and third and fourth wires engaged with the elastic body,
The third locking portion includes an elastic body, and fifth and sixth wires engaged with the elastic body,
The fourth locking portion includes an elastic body, and seventh and eighth wires engaged with the elastic body,
The first elastic force transmission portion is constituted by a first pulley in which a first wire of the first locking portion and a third wire of the second locking portion are wound in opposite directions. ,
The second elastic force transmission part is constituted by a second pulley in which a second wire of the first locking part and a fourth wire of the second locking part are wound in opposite directions. ,
The third elastic force transmitting portion rotates about the same axis as the second pulley, and the fifth wire of the third locking portion and the seventh wire of the fourth locking portion Constituted by a third pulley with the wire wound in the opposite direction;
The fourth elastic force transmitting portion is constituted by a fourth pulley in which a sixth wire of the third locking portion and an eighth wire of the fourth locking portion are wound in opposite directions. An articulated arm mechanism. The articulated arm mechanism according to claim 8,
The articulated arm mechanism, wherein each of the elastic bodies constituting the first to fourth locking portions is a tension coil spring. The articulated arm mechanism according to claim 7,
The first joint portion is fixed to the first joint shaft serving as the center of rotation, the first elastic force transmission portion fixed to the base portion, and the first arm, and A first power transmission unit that rotates together with the first arm by the first actuator around a joint axis;
The second joint portion is fixed to the second joint axis serving as the center of rotation, the second elastic force transmission portion fixed to the second arm, and the second arm. A second power transmission unit that rotates together with the second arm by the second actuator about the second joint axis; and the third elastic force transmission unit that is fixed to the first arm. ,
The third joint portion is fixed to the third joint axis serving as the center of rotation, the fourth elastic force transmitting portion fixed to the third arm, and the third arm. A multi-joint arm mechanism comprising: a third power transmission unit that rotates together with the third arm by the third actuator around the three joint axes. The multi-joint arm mechanism according to claim 10,
The first, second, and third actuators are constituted by first, second, and third motors, respectively, to which gears are attached,
The first power transmission unit is configured by a gear that meshes with a gear attached to the first motor,
The second power transmission unit is configured by a gear that meshes with a gear attached to the second motor,
The articulated arm mechanism is characterized in that the third power transmission unit is configured by a gear meshing with a gear attached to the third motor.

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