JP6904558B2 - Joint mechanism, articulated manipulator using this, and manufacturing method of these - Google Patents

Description

The present invention relates to a joint mechanism, an articulated manipulator using the joint mechanism, and a method for manufacturing the same.

As a remote control manipulator for extracting molten nuclear fuel in a nuclear power plant after a severe accident, an ultra-long, ultra-multi-degree-of-freedom articulated manipulator with a large hand output and an elongated arm is required.

A conventional articulated manipulator has a base, multiple joints, multiple links serially connected by joints and connected to the base, multiple pulleys axially attached to the joints, and at least one revolution on the pulley. It is composed of a plurality of metal wires wound around the metal wires and a plurality of joints (motors) for adjusting the tension of the metal wires (see: Non-Patent Documents 1 and 2 and Patent Document 1). For example, as shown in FIG. 15, a large number of links 101-1, 101-2, ... (Only three are shown) are serially rotatably connected by each joint (axis) 102-1, 102-2, ... It is connected to the base 103 via a fixed link 101-0. Pulleys 104 (1, 1), 104 (1, 2), 104 (1, 3) are slidably attached to the joint 102-1, and pulleys 104 (2, 2), 104 (2, 2) are attached to the joint 102-2. The 104 (2, 3) is slidably attached to the shaft, and the pulley 104 (3, 3) is slidably attached to the joint 102-3. The metal wire 105-1 is wound around the pulley 104 (1, 1) one turn, and the fixed end portion 105-1a of the metal wire 105-1 is fixed to the link 101-1. That is, the link 101-1 rotates with the rotation of the pulleys 104 (1, 1). Further, the metal wire 105-2 is wound around the pulleys 104 (1, 2) and 104 (2, 2) once, and the fixed end portion 105-2a of the metal wire 105-2 is fixed to the link 101-2. There is. That is, the link 101-2 rotates with the rotation of the pulley 104 (2, 2). Further, the wire 105-3 is wound around the pulleys 104 (1, 3), 104 (2, 3), 104 (3, 3) once, and the fixed end 105-3a of the metal wire 105-3 is linked 101. It is fixed at -3. That is, the link 101-3 rotates with the rotation of the pulley 104 (3, 3). In order to suppress an increase in the weight of a large number of links 101-1, 101-2, ..., Each link 101-1, 101-2, ... Is connected via metal wires 105-1, 105-2, ... Actuators (motors) 106-1, 106-2, ... For driving are provided in the base 103 of the articulated manipulator.

In FIG. 15, for example, when the actuator 106-3 is driven so as to wind up the metal wire 105-3, the links 101-1, 101-2, and 101-3 are raised at the same time. Further, when the actuator 106-1 is further driven so as to wind up the metal wire 105-1, only the link 101-1 rises.

A method for fixing the fixed ends 105-1a, 105-2a, and 105-3a of the metal wires 105-1, 105-2, and 105-3 to the links 101-1, 101-2, and 101-3 is shown in FIG. As described above, it is performed by the clamping method, caulking method, etc., but since the friction coefficient of the metal wires 105-1, 105-2, 105-3 (for example, stainless steel) is large, the fixed ends 105-1a, 105-2a, 105 The strength efficiency of -3a can be increased to 95-100% (see: Mechanical Design Handbook, Metal Wire Rope End Treatment Method). Therefore, there is little risk that the fixed end portions 105-1a, 105-2a, 105-3a will break or slip through.

Shigeo Hirose, Shone Ma: Development of Wire Interference Driven Articulated Manipulator, Proceedings of the Society of Instrument and Control Engineers, 26-11, 1291/1298 (1990) Tomoyuki Ishii, Atsushi Haishi, Shigeo Hirose: Explanation of self-weight compensation mechanism by wire and double pulley and performance evaluation of Float Arm V, 10th Anniversary Academic Lecture of Robotics Society of Japan, 1002

Japanese Unexamined Patent Publication No. 1003-89090

However, in the above-mentioned conventional articulated manipulator, since each joint is driven by traction of a metal wire, there is a problem that the weight of the articulated manipulator becomes excessive as the number of joints increases.

In order to solve the above-mentioned problems, the joint mechanism according to the present invention is fixed to a grooved pulley, a lightweight high-strength low-friction coefficient material wire wound around the grooved pulley, and a grooved pulley to be lightweight and high-strength. The fixed end of the low friction coefficient material wire is provided with a fixed link, the fixed end of the lightweight high strength low friction coefficient material wire constitutes a loop by the knot method, and the loop is passed through the pin of the link and fixed. It is what has been done.

Further, in the method for manufacturing the joint mechanism according to the present invention, the diameter D of the grooved pulley and the diameter D of the grooved pulley in which the ratio D / d of the diameter D of the grooved pulley and the diameter d of the lightweight, high-strength, low-friction coefficient material wire is equal to or more than a predetermined value and A process for determining the diameter d of a lightweight, high-strength, low-friction coefficient material wire, a process for evaluating the strength efficiency of a fixed end of a lightweight, high-strength, low-friction coefficient material wire, and a lightweight, high-strength, low-friction coefficient material wire. The process for determining the groove structure of the grooved pulley according to the strength efficiency when the is wound around the grooved pulley, and the pseudo-friction coefficient of the lightweight, high-strength, low-friction coefficient for the grooved pulley for which the groove structure has been determined. Lightweight, high strength, low friction coefficient due to frictional force by material wire, and light weight, high strength, low friction coefficient according to the tension damping rate of the material wire. It includes a step for calculating the winding angle of the pulley.

According to the present invention, the weight can be reduced by using the lightweight, high-strength, low-coefficient material wire, and at the fixed end of the lightweight, high-strength, low-coefficient material wire due to the low friction coefficient of the lightweight, high-strength, low-coefficient material wire. Breakage and the like can be suppressed by a grooved pulley.

It is a front view which shows the embodiment of the joint mechanism which concerns on this invention. It is a photograph which shows the example of the high-strength chemical fiber wire of FIG. It is a photograph which shows the example of the grooved pulley of FIG. It is a flowchart for demonstrating the manufacturing method of the joint mechanism of FIG. It is a graph which shows the strength efficiency characteristic with respect to a pulley diameter D / wire diameter d in step 401 of FIG. It is a graph which shows the evaluation of the strength efficiency of the fixed end part by the special processing method in step 402 of FIG. It is a graph which shows the evaluation of the strength efficiency of the fixed end part by the clamp method in step 402 of FIG. It is a graph which shows the evaluation of the strength efficiency of the fixed end part by the knot method in step 402 of FIG. The shape determination of the grooved pulley in step 403 of FIG. 4 will be described, where (A) is a shape parameter, (B) is a diagram showing an example of the shape parameter of (A), and (C) is (B). It is a table which shows the strength efficiency of. 4 is for explaining the friction coefficient and the pseudo-friction coefficient in step 404 of FIG. 4, in which FIG. 4A is a diagram showing tension, FIG. 4B is a diagram showing normal force in the case of a grooveless pulley, and FIG. 4C is a diagram showing normal force. It is a figure which shows the normal force in the case of a grooved pulley. It is a figure which shows the tensile test apparatus used in step 404 of FIG. It is a graph which shows the pseudo-friction coefficient measured in step 404 of FIG. It is a front view for demonstrating the winding angle of the high-strength chemical fiber wire in step 405 of FIG. It is a graph which shows the tension attenuation rate with respect to the winding angle in step 405 of FIG. It is a perspective view which shows the conventional articulated manipulator. It is a figure for demonstrating the fixing method of the fixed end portion of the metal wire of FIG.

FIG. 1 is a front view showing an embodiment of a joint mechanism according to the present invention. In FIG. 1, in order to simplify the structure, the number of joints is set to 1, and only the outermost joint is shown.

In FIG. 1, the articulated manipulator has links 3-1 and 3-2 serially connected by a base 1, a joint (axis) 2, and a joint 2 and coupled to the base 1. A grooved pulley 4 is rotatably attached to the joint 2 with respect to the link 3-1. The link 3-2 is fixed to the grooved pulley 4 and is rotated by driving the actuator 6 provided on the base 1 with the high-strength chemical fiber wire 5 wound around the grooved pulley 4. In this case, the fixed end portion 5a of the high-strength chemical fiber wire 5 is fixed to the outermost link 3-2.

The high-strength chemical fiber wire 5 is composed of high-density chemical fiber, for example, high-density polyethylene fiber, and has a very high specific strength (tensile strength per unit weight) as compared with metal, for example, stainless steel. It can be planned. For example, the high-density polyethylene fiber is, for example, Dyneema (registered trademark) shown in FIG. 2 (A) or Zylon (registered trademark) / Dyneema (registered trademark) shown in FIG. 2 (B). On the other hand, since the friction coefficient of the high-strength chemical fiber wire 5 is small, the strength efficiency of the fixed end portion 5a of the high-strength chemical fiber wire 5 is small, and the fixed end portion 5a is liable to break or slip through. In order to prevent such breakage, slip-through, etc. of the fixed end portion 5a, the present invention employs the grooved pulley 4 shown in FIG. 3 as the pulley.

Next, a method of manufacturing the joint mechanism of FIG. 1 will be described with reference to the flowchart of FIG.

First, in step 401, the diameter D of the grooved pulley 4 and the diameter d of the high-strength chemical fiber wire 5 of FIG. 1 are determined. In this case, the grooved pulley 4 is assumed to have no groove, and the diameter D of the grooved pulley 4 and the diameter d of the high-strength chemical fiber wire 5 are determined by using the strength efficiency E by D / d. For the strength efficiency E here, a tensile test is performed in which the high-strength chemical fiber wire 5 is wound around a grooved pulley 4 at a predetermined angle and both ends of the high-strength chemical fiber wire 5 are pulled, and the maximum tension when the high-strength chemical fiber wire 5 is broken = fixing force. Is divided by the strength of the element of the high-strength chemical fiber wire 5, for example, 2.14 kN (in the case of Dyneema) and 2.99 (in the case of Zylon / Dyneema). In this case, the strength efficiency characteristics are shown in FIG. As shown in FIG.
D / d ≧ 15 (1)
If so, the strength efficiency E is 90% or more. From the viewpoint of weight reduction, select a value as small as possible for the diameter D of the grooved pulley 4 within the range that satisfies the equation (1), and high-strength chemical fiber within the range that does not break at the maximum tension required from the design specifications. The diameter d of the wire 5 may be selected as small as possible. For example, the diameter D of the grooved pulley 4 and the diameter d of the high-strength chemical fiber wire 5 are set to D = 37.5 mm (2).
d = 2.0 mm (3)
To decide. In this case, D / d = 18.75, and the strength efficiency E can achieve 92%, which is close to 100%.

Next, in step 402, the strength efficiency E of the fixed end portion 5a of the high-strength chemical fiber wire 5 of FIG. 1 having a diameter d = 2.0 mm determined in step 401 is evaluated. The strength efficiency E here fixes the fixed end portion 5a of the high-strength chemical fiber wire 5 to the link 3-2 (not necessarily the link), and pulls the high-strength chemical fiber wire 5 and the link 3-2. A tensile test is performed, and the maximum tension when the fixed end portion 5a breaks or slips through = the fixing force is divided by the strength of the element of the high-strength chemical fiber wire 5.

FIG. 6 shows an evaluation of the strength efficiency E of the fixed end portion 5a of the high-strength chemical fiber wire 5 when performed by a special processing method. The evaluation was performed by passing a loop of the high-strength chemical fiber wire 5 crimped or machined through a pin having a diameter of 10 mm provided on the link 3-2 (not necessarily the link). That is, when there is one caulking member, the strength efficiency E is very small, but when the number of caulking members is two or three, the strength efficiency E becomes large, and the strength efficiency E = 92% in step 401 is reached. However, it is generally small. Also, in the case of sewing, the strength efficiency E is very small when the machined portion is 10 mm, but the strength efficiency E is large when the machined portion is 25 mm or 40 mm, and the strength efficiency E in step 401 is increased. = 92%, but generally small. Although such a special processing method enables stable processing, the length of the high-strength chemical fiber wire 5 cannot be changed.

FIG. 7 shows an evaluation of the strength efficiency E of the fixed end portion 5a of the high-strength chemical fiber wire 5 when the clamp method is used. Examples of the clamping method include a small clamping method using two screws having a torque of 1.2 Nm, a large clamping method using six screws having a torque of 1.2 Nm, and a cylindrical clamping method using two screws having a torque of 1.2 Nm. Further, in the cylindrical clamping method, after applying a clamping force, the cylinder is wound around the cylinder to disperse the clamping force and reduce the load on the high-strength chemical fiber wire 5, thereby increasing the fixing force due to the frictional force of the winding (A). ), There is a type (B) in which the high-strength chemical fiber wire 5 is wound around a cylinder only half a circumference and then a clamping force is applied to obtain strength efficiency due to the influence of D / d. According to the clamping method, the strength efficiency E is relatively large in the large-scale clamping method and the cylindrical clamping method, but is generally smaller than the strength efficiency E = 92% in step 401. Although the clamping method is stable, both mass and volume increase in order to obtain high strength efficiency.

FIG. 8 shows an evaluation of the strength efficiency E of the fixed end portion 5a of the high-strength chemical fiber wire 5 when the knotting method is used. The evaluation was carried out by passing a loop of the high-strength chemical fiber wire 5 by knotting through a pin having a diameter of 6 mm provided on the link 3-2 (not necessarily the link). Examples of the knotting method include a double-joining method, a double-eight knotting method, a bowline method, and a modified bowline method. According to the knotting method, the strength efficiency E is relatively small as compared with the special processing method and the clamping method, for example, E = about 50%. The knotting method is easy to fix, and the length of the high-strength chemical fiber wire 5 can be changed.

As described above, the evaluation of the strength efficiency E at the fixed end portion 5a of the high-strength chemical fiber wire 5 having a low friction coefficient in step 402 is generally small. For example, the strength efficiency E = E2 = 50% in this case. In order to compensate for such a small strength efficiency E2 at the fixed end portion 5a, the present invention generates a frictional force of the high strength chemical fiber wire 5 in the grooved pulley 4 and has high strength up to the strength efficiency E2 of the fixed end portion 5a. The tension of the chemical fiber wire 5 is reduced.

Next, in step 403, the groove shape of the grooved pulley 4 of FIG. 1 is determined. In this case, the strength efficiency E when the high-strength chemical fiber wire 5 is wound around the grooved pulley 4 at a predetermined angle is used for determination. The strength efficiency E here is determined by performing a tensile test in which the high-strength chemical fiber wire 5 is wound around a grooved pulley 4 at a predetermined angle and both ends of the high-strength chemical fiber wire 5 are pulled, and the maximum tension when the wire is broken = fixing force. Is divided by the strength of the element of the high-strength chemical fiber wire 5, for example, 2.14 kN (in the case of Dyneema). That is, the groove shape of the grooved pulley 4 based on D = 37.5 mm and d = 2.0 mm is defined by the groove angle α and the groove bottom diameter φ as shown in FIG. 9A. In this case, since the high-strength chemical fiber wire 5 is so soft that it is greatly deformed, the strength efficiency E fluctuates. For example, α = 30 °, 45 °, 60 °, φ = 0.5 mm, 1.0 mm, 1.5 mm, and the strength efficiency E is measured for the nine shapes shown in FIG. 9B. As a result, the strength efficiency E shown in FIG. 9 (C) was obtained. Therefore, the groove shape is determined to be α = 30 ° and φ = 1.5 mm, which have the largest strength efficiency E = E1 = 98%. The larger the number of measurements of α and φ, the better.

Next, in step 404, the pseudo-friction coefficient μ'of the high-strength chemical fiber wire 5 with respect to the grooved pulley 4 is measured.

The friction coefficient μ and the pseudo-friction coefficient μ'will be described with reference to FIG. As shown in FIG. 10A, the wire is wound around a pulley to generate tensions T1 and T2, and the tensions T1 and T2 are measured by a force sensor. The tensile test device is shown in FIG. When the pulley shown in FIG. 10B has no groove, the normal force Nd1 received by the high-strength chemical fiber wire 5 from the grooveless pulley is small, so that the belt theory of the oiler is followed. In other words
μ =-(1 / θ) ln (T2 / T1)
However, μ has a friction coefficient between the grooveless pulley and the high-strength chemical fiber wire 5, for example 0.04.
θ is the winding angle (contact angle) of the high-strength chemical fiber wire 5 with respect to the pulley.
Is. On the other hand, as shown in FIG. 10 (C), when the pulley is grooved, the high-strength chemical fiber wire 5 receives the normal force Nd2 from both sides of the groove of the grooved pulley 4, so that the belt theory of the oiler and the V-belt From theory
μ'=-(1 / θ) ln (T2 / T1)
However, μ'is a pseudo-friction coefficient,
μ'= μ / (sin (α/2) + μcos (α / 2))
Will be. Actually, as shown in FIG. 12, the pseudo-friction coefficient μ'tends to be different from the theoretical value because the high-strength chemical fiber wire 5 is soft, and also depends on the groove bottom diameter φ of the grooved pulley 4. For example, when θ = 1350 ° (that is, 3 rotations + 270 °), α = 30 °, and φ = 1.5 mm,
μ'= 0.071
Met. The theoretical value μ'is 0.145.

Finally, in step 405, the winding angle θ of the high-strength chemical fiber wire 5 is calculated using the pseudo-friction coefficient μ'measured in step 404. As shown in FIG. 13, the winding angle θ is such that the tension T1 at the strength efficiency E1 = 98% is increased by the frictional force of the high-strength chemical fiber wire 5 to the strength efficiency E2 of the fixed end portion 5a. It is set to be small. In other words
θ =-(1 / μ') ln (T2 / T1)
=-(1 / 0.071) ln (0.5 / 0.98)
= 543 ° (that is, 1 rotation + 183 °)
In addition, referring to FIG. 14 showing the tension damping rate (T2 / T1) with respect to the theoretical value μ, it can be seen that in the case of the grooveless pulley, θ≈1000 ° and θ = 543 ° is significantly small. However, it is larger than the theoretical value μ when α = 30 ° and θ≈300 ° when μ = 0.0145.

Thus, for example, for the grooved pulley 4,
Diameter D = 37.5 mm
Groove angle α = 30 °
Groove bottom diameter φ = 1.5 mm
As for the high-strength chemical fiber wire 5,
2.0 mm in diameter
Winding angle (contact angle) θ = 543 °
And.

In the above-described embodiment, the number of joints is 1, but it goes without saying that the present invention can be applied to an articulated manipulator having a plurality of joints as shown in FIG.

Further, the high-strength chemical fiber wire 5 in the above-described embodiment can be used as another lightweight, high-strength, low-coefficient material in addition to the high-strength polyethylene fiber. For example, it can be a para-aramid fiber, a polyarylate fiber, a polyparaphenylene benzobisoxazar (PBO) fiber, and a carbon fiber.

Moreover, the present invention may be applied to any modification of the obvious scope of the embodiments described above.

1: Base 2: Joint 3-1, 3-2: Link 4: Grooved pulley 5: High-strength chemical fiber wire 5a: Fixed end 101-0: Fixed link 101-1, 101-2, ...: Link 102-1, 102-2, ...: Joint 103: Base 104 (1, 1), 104 (1, 2), 104 (1, 3); 104 (2, 2), 104 (2, 3), 104 (3, 3): Pulleys 105-1, 105-2, 105-3, ...: Wires 105-1a, 105-2a, 105-3a, ...: Fixed ends 106-1, 106-2, ...: Actuator (motor)

Claims (10)

Grooved pulley and
A lightweight, high-strength, low-coefficient material wire wound around the grooved pulley,
Provided with a link fixed to the grooved pulley and to which the fixed end of the lightweight, high-strength, low-coefficient material wire is fixed .
A joint mechanism in which the fixed end of the lightweight, high-strength, low-coefficient material wire constitutes a loop by a knot method, and the loop is passed through a pin of the link and fixed. The joint mechanism according to claim 1, wherein each of the lightweight, high-strength, low-friction coefficient material wires is made of high-strength chemical fiber. The joint mechanism according to claim 2, wherein the high-strength chemical fiber is any one of high-strength polyethylene, para-aramid fiber, polyarylate fiber, PBO fiber, and carbon fiber. The joint mechanism according to claim 1, wherein the grooved pulley has a groove defined by a groove angle and a groove bottom diameter. Base and
With multiple joints
With a plurality of links serially connected by the joint and connected to the base,
A plurality of pulleys slidably attached to the joint,
A plurality of lightweight, high-strength, low-coefficient material wires wound around the pulley,
Each of the lightweight, high-strength, low-coefficient material wires is equipped with a plurality of actuators for adjusting the tension.
The outermost pulley around which each of the lightweight, high-strength, low-coefficient material wires is wound is a grooved pulley.
An articulated manipulator in which the fixed ends of each of the lightweight, high-strength, low-coefficient material wires form a loop by knotting, and the loop is passed through and fixed to the pin of the outermost link. The articulated manipulator according to claim 5, wherein each of the lightweight, high-strength, low-coefficient material wires is made of high-strength chemical fiber. The articulated manipulator according to claim 6, wherein the high-strength chemical fiber is any one of high-strength polyethylene, para-aramid fiber, polyarylate fiber, PBO fiber, and carbon fiber. The articulated manipulator according to claim 5, wherein the grooved pulley has a groove defined by a groove angle and a groove bottom diameter. The method for manufacturing a joint mechanism according to claim 1.
The diameter D of the grooved pulley and the lightweight, high-strength, low-friction coefficient material wire whose ratio D / d of the diameter D of the grooved pulley to the diameter d of the lightweight, high-strength, low-friction coefficient material wire is equal to or greater than a predetermined value. The process for determining the diameter d and
A process for evaluating the strength efficiency of the fixed end of the lightweight, high-strength, low-friction coefficient material wire, and
A step for determining the groove structure of the grooved pulley according to the strength efficiency when the lightweight, high-strength, low-friction coefficient material wire is wound around the grooved pulley.
A step for measuring the pseudo-friction coefficient of the lightweight, high-strength, low-friction coefficient material wire with respect to the grooved pulley for which the groove structure has been determined, and
Winding of the grooved pulley of the lightweight, high-strength, low-friction coefficient material wire according to the pseudo-friction coefficient and the tension damping rate of the lightweight, high-strength, low-friction coefficient material wire due to the frictional force of the lightweight, high-strength, low-friction coefficient material wire. A method of manufacturing a joint mechanism comprising a process for calculating an angle. The method for manufacturing an articulated manipulator according to claim 5.
The diameter D of the grooved pulley and the lightweight, high-strength, low-friction coefficient material wire whose ratio D / d of the diameter D of the grooved pulley to the diameter d of the lightweight, high-strength, low-friction coefficient material wire is equal to or greater than a predetermined value. The process for determining the diameter d and
A process for evaluating the strength efficiency of the fixed end of the lightweight, high-strength, low-friction coefficient material wire, and
A step for determining the groove structure of the grooved pulley according to the strength efficiency when the lightweight, high-strength, low-friction coefficient material wire is wound around the grooved pulley.
A step for measuring the pseudo-friction coefficient of the lightweight, high-strength, low-friction coefficient material wire with respect to the grooved pulley for which the groove structure has been determined, and
Winding of the grooved pulley of the lightweight, high-strength, low-friction coefficient material wire according to the pseudo-friction coefficient and the tension damping rate of the lightweight, high-strength, low-friction coefficient material wire due to the frictional force of the lightweight, high-strength, low-friction coefficient material wire. A method of manufacturing an articulated manipulator that includes a process for calculating an angle.

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