JPH05309587A - Robot arm - Google Patents

Abstract

PURPOSE:To reduce flexture and flexural oscillation in the rotational and parallel movement of a robot arm by setting a non-flexture point which twists but does not flex at the tip of the robot arm even if loads are applied in the moving direction so that the point can correspond to the center of gravity of a point installation member. CONSTITUTION:A robot arm 15 is composed of a material which has anisotropy in at least one part of it, and the position of a non-flexture point Q at the tip of the robot arm is set to correspond to the center of gravity of a point installation member 16 (J) or the center of gravity of the point installation member 16 and a transferred object retained by the point installation member. This constitution prevents the robot arm 15 from flexing due to the inertia force of the point installation member 16 and transferred object at the start or end of parallel or rotational movement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot arm,
In particular, the present invention is intended to improve the positioning accuracy by reducing the flexure and flexural vibration that occur in the robot arm during rotational movement or parallel movement.

[0002]

2. Description of the Related Art FIG. 17 shows an example of a conventional robot arm. The robot arm 1 is made of a mechanically isotropic material, and one of the fixed ends 1a of the robot body 2 is rotationally moved (shown by an arrow A) or translated (shown by an arrow B). 3 is attached to the other free end 1b, and a tip attaching member 5 which is a robot hand for holding the object to be conveyed 4 is attached to the other free end 1b.

When the robot arm 1 rotates or moves in parallel without gripping the object to be conveyed 4, the inertial force of the tip mounting member 5 causes a load having a center of gravity C of the tip mounting member 5 itself as an application point. And the center of gravity C is on the geometric main axis of the robot arm 1 (the axis connecting the centroids of the cross section of the robot arm 1) shown by G in the figure, the bending force acts on the robot arm 1. To do. Then, due to the bending force, the robot arm 1 is flexed, and flexural vibration is generated.

When the center of gravity G of the robot arm 1 is not on the geometrical main axis G, the inertial force of the tip mounting member 5 acts on the robot arm 1 as a bending and twisting force, causing the robot arm 1 to bend. Twist occurs, which causes flexural vibration and torsional vibration.

On the other hand, when the object 4 to be conveyed is held by the tip mounting member 5 and is rotated or translated, the object 4 to be conveyed is held by the tip mounting member 5 as in the above case. At this point, an inertial force having the center of gravity D as an application point acts, and causes flexural vibration (vibration in the direction of arrow P in FIG. 17) and torsional vibration (vibration in the direction of arrow S in FIG. 17).

Conventionally, due to the flexural vibration and the torsional vibration, the accuracy of the stop position of the robot arm 1 is lowered, and it is difficult to accurately grasp the object 4 to be conveyed.
The grasped transported object 4 could not be accurately placed at a predetermined position. In particular, when high precision or high speed is required or in a robot arm having low rigidity, the influence of the vibration is great.

On the other hand, by increasing the rigidity of the robot arm, it is possible to prevent the occurrence of bending even when the load due to the inertial force acts.

Further, there has been proposed a method of reducing the flexural vibration by adjusting the moving speed of the robot arm 1 at the start and end of the rotational movement or the parallel movement. That is, a method has been proposed in which the inertial force is reduced by reducing the acceleration / deceleration at the start and end of the rotation or parallel movement, thereby reducing the load that causes the flexure and flexural vibration.

[0009]

However, the method of increasing the rigidity of the robot arm as described above increases the weight and is not suitable for a robot arm which moves at high speed. Furthermore, it is impossible to completely set the deflection to "0" no matter how much the rigidity is increased. Further, the method of adjusting the moving speed due to the flexural vibration as described above complicates the structure and control, and increases the cost required for manufacturing and operating the robot.

The present invention has been made in order to solve the problems of flexure and flexural vibration in the conventional robot arm as described above. When the robot arm is rotated and translated, the weight of the robot arm is not increased. It is intended to reduce the flexure and flexural vibration of the robot, simplify the control mechanism, and reduce the weight of the robot arm.

[0011]

The present invention has been made based on the following principle. In a cylindrical or solid robot arm formed at least in part by using an anisotropic material such as a fiber-reinforced composite material, the angle (fiber angle) of the reinforcing fiber in the anisotropic material with respect to the geometric main axis of the robot arm. Are partially different in the circumferential direction and at least in a part in the thickness direction, on the arbitrary straight line (hereinafter referred to as a reference axis) orthogonal to the geometric main axis of the robot arm at the tip of the robot arm. Except when the fiber configuration of the robot arm is the target on both sides, there is a point of action (hereinafter referred to as a non-deflection point) that causes twisting but does not cause bending at the tip of the robot arm even when a load is applied. ..

The position of this non-deflection point is the fiber angle,
The fiber angle can be appropriately set by changing the arrangement of the positions where the fiber angles are different.

For example, in the pipe-shaped structure 8 made of fiber reinforced resin shown in FIGS. 18 and 19, the cylindrical coordinates [(r, θ, Z) system coordinates] are set so as to coincide with the geometric main axis G thereof. However, 0 ° ≦ θ <180 ° regardless of the Z coordinate and r coordinate
The angle of the fiber F (fiber angle) is α = 30 ° in the portion 8a, while the fiber angle is β = −30 ° in the portion 8b where 180 ° ≦ θ <360 °.

As shown in FIG. 20, one end of this pipe-shaped structure 8 is a fixed end 8c and the other end is a free end 8d so that the Z-axis is horizontal, and a load is applied vertically downward to the end thereof. Add. Here, as shown in FIG.
At the tip of the pipe-shaped structure 8, the pipe-shaped structure 8
Axis orthogonal to the geometrical principal axis G (Z axis) of, that is, the reference axis M
Then, a straight line of θ = 0 ° is taken, and the fixed end 8c is fixed so that the reference axis M becomes horizontal.

Further, the origin of the reference axis M is set at the intersection with the Z axis, and whether the reference axis M is positive or negative is determined in a region where the θ coordinate of the pipe-shaped structure 8 is positive and the geometrical relationship with the reinforcing fiber F. The direction in which the main axis G forms an acute angle on the free end 8d side is positive.
When the position for applying a vertical load is changed on the reference axis M, as shown in FIG. 21, the deflection of the free end 8d or the non-deflection in which the displacement of the free end 8d with respect to the load direction becomes zero. There is a point Q. That is, as shown in FIG. 22, when a vertical load is applied to the non-deflection point Q as shown by an arrow R, the pipe-shaped structure 8 is twisted and the reference axis is M.
Although it rotates from the horizontal state shown in to the state shown in M ', the free end 8d of the pipe-shaped structure 8 is not displaced in the vertical direction, that is, does not bend.

On the other hand, as shown in FIG. 23, when the fiber angles α and β are changed to various angles of 0 ° to 90 ° while maintaining the relation of β = -α, the fiber angles α and β do not bend. The position of the point Q from the origin, that is, the distance from the geometric main axis G changes.

More specifically, as in the example shown in FIGS. 18 and 19, the portions 8a and 18 satisfying 0 ° ≦ θ <180 °.
When the fiber angle is made different in the portion 8b where 0 ° ≦ θ <360 °, the position of the non-deflection point Q on the reference axis from the origin is l = (− π · S ₁₁ · L) / (3S ₁₆ ).
Here, S ₁₁ and S ₁₆ are constants determined by the type of fiber-reinforced composite material used and the laminated structure.

The present invention is characterized in that a pipe-like structure, which is made of a combination of materials having mechanical anisotropy as described above and exhibits peculiar deformation behavior, is used for a robot arm.

That is, according to the present invention, the robot has one fixed end connected to the actuating member and the other end free end connected to a robot hand for grasping an object to be conveyed or a gun spray for working. An arm, which is made of a material having anisotropy in at least a part thereof, causes a twist at the tip of the robot arm at a point on an axis orthogonal to the moving direction of the robot arm even if a load in the moving direction is applied. The present invention provides a robot arm characterized in that a non-deflecting point, which is an action point that does not bend, is set so as to coincide with the center of gravity of the tip mounting member.

Further, according to the present invention, the robot has one end fixed to the actuating body and the other end free end connected to a robot hand for gripping a transported object or a tip attaching member such as a gun spray for working. The arm is made of a material having anisotropy in at least a part thereof, and the non-deflection point is made to coincide with the center of gravity of the tip mounting member and the transported object held by the tip mounting member. The present invention provides a robot arm characterized by the above.

Specifically, in the robot arm, a fiber-reinforced composite material is used as a forming material, and the fiber angles of the fiber-reinforced composite material are partially different in the circumferential direction and at least partially in the thickness direction. Therefore, it is preferable to set the non-deflection point at the above-mentioned predetermined position. Further, in the present invention, the non-deflection point described above is the center of gravity of the tip mounting member,
Alternatively, an additional mass may be attached to the tip attaching member so that the center of gravity of the tip attaching member and the conveyed object held by the tip attaching member coincides with the center of gravity.

As the fiber-reinforced composite material, glass fiber, carbon fiber, various organic fibers, alumina fiber, silicon carbide fiber, metal fiber and / or a fiber made of a mixture thereof, a woven cloth, a mat or the like is used as the reinforcing fiber. A fiber reinforced resin using a resin such as polyamide, epoxy or polyester as the resin is preferably used.

The entire robot arm may be formed of the above-mentioned fiber reinforced resin, and in addition to the fiber reinforced resin, an anisotropic material such as fiber reinforced rubber, fiber reinforced metal, orientated rubber, and / or the like. Alternatively, an isotropic material such as resin or rubber that does not contain fibers may be partially combined. Further, the robot arm made of the above-mentioned materials may have the same length in the axial direction, or the structure may be changed in the axial direction. In the present invention, the material and configuration of the arm are not limited as long as the non-deflection point of the robot arm can be set at the above-mentioned predetermined position by using at least a part of the anisotropic material.

[0024]

As described above, in the robot arm according to the present invention, when the non-deflection point is set to coincide with the center of gravity of the tip mounting member, the robot arm is started or stopped when the rotational movement or the parallel movement is started. The arm is not bent, and the positioning accuracy when the work tip mounting member grips the transported object is improved.

Further, when the non-deflection point of the robot arm is set so as to pass through the center of gravity of the tip attaching member and the conveyed object gripped by the tip attaching member, the conveyed article is moved in the same manner as in the above case. Flexural vibration does not occur at the time of starting or stopping the movement in the gripped state, and the positioning accuracy at the time of placing the transported object gripped by the tip mounting member at a predetermined position is improved. Furthermore, when the additional mass is attached to the tip mounting member so that the non-deflection point of the robot arm matches the center of gravity of the tip mounting member or the center of gravity of the tip mounting member and the transported object, Similar to the above case, flexural vibration does not occur at the time of starting or stopping the movement, and the positioning accuracy is improved.

[0026]

Next, the present invention will be described in detail with reference to the embodiments shown in the drawings. In the first embodiment of the present invention shown in FIG. 1, the robot 11 is of a type used for painting, and as shown by an arrow A, rotation that constitutes an operating body that rotates around an axis H on the main body 12. A portion 13 is provided, and the end portion of the robot arm 15 is attached to the end surface 13a of the rotating portion 13 to form a fixed end 15a.
The other end is used as a tip attachment member to form a free end 15b to which a spray gun 16 for painting is attached. A paint tank 16a is attached to the spray gun 16.
The center of gravity J of the weight of the spray gun 16 is the above-mentioned additional mass 16
Due to the weight of a, the robot arm 15 is located at the tip of the robot arm 15 on the lower side in the direction orthogonal to the geometrical main axis G at a distance of l ₁ = 325 mm.

The robot arm 15 is in the form of a pipe made of FRP (carbon fiber reinforced epoxy resin). As shown in FIG. 2, the length L from the fixed end 15a to the free end 15b is 400 mm and the inner diameter ID is 16 mm. Outer diameter OD is 19mm
As, through this free end 15b, and
The material, the fiber angle, and the fiber angle are set so that the non-deflection point Q on the reference axis M orthogonal to the rotational movement direction A and the geometric main axis G of the robot arm 15 coincides with the center of gravity J of the spray gun 16. The different parts are set.

That is, if a cylindrical coordinate system is set so that the geometric main axis G and the Z axis coincide with each other, as shown in FIGS. 3 (A) to 3 (C), regardless of the Z coordinate and the r coordinate, 90 ° ≤ θ <
The fiber angle is α = 30 ° in the 270 ° portion 15c, while the fiber angle is β = -30 ° in the portion 15d in which 0 ° ≦ θ <90 ° and 270 ° <θ <360 °. , 15d are formed by laminating 12 layers of prepreg sheets.

The manufacturing method of the robot arm 15 is as follows. The mandrel is cut into prepreg sheets having a half circumference length so that the fiber angles are α and β, respectively.
After being laminated in order at 15d, a wrapping tape is spirally wound and pressed, and then cured in an oven to manufacture. The robot arm 15 manufactured as described above has an elastic modulus Exx = 11100 Kg / mm ² , Ey when prepregs having the same fiber angle are laminated.
y = 880.8 Kg / mm ² , Exy = 516.8 Kg
/ Mm ² and the Poisson's ratio is νxy = 0.288.

In the robot arm 15 of the first embodiment, the fiber angle of one part in the circumferential direction is made different from that of the other part as described above, so that the rotation direction of the robot arm 15 and the direction orthogonal to the geometric main axis G are orthogonal to each other. The non-deflection point Q on the reference axis M of is matched with the center of gravity J of the spray gun 16. For the non-deflected point Q on the reference axis M, the geometric main axis G
And, when a load is applied in the direction orthogonal to the reference axis and a bending and twisting force is applied, the peculiar deformation behavior that a twist occurs at the tip of the arm but no bending occurs is shown.
As described above.

Therefore, the robot arm 15 of the first embodiment.
Then, when the rotating unit 13 starts rotating movement or stops rotating, the inertial force of the spray gun 16 is the center of gravity J.
Since the action direction is the same as the rotation direction A, a load is applied to the non-deflection point Q to bend and twist the robot arm 15, but the robot arm 15 is twisted but does not bend. Absent. Therefore, even if torsional vibration occurs, flexural vibration does not occur, the accuracy of stopping the arm tip at a predetermined stop position is improved, and the spray gun 16 is accurately positioned relative to the material to be coated provided at the predetermined position. Can be painted from.

As shown in FIG. 4, in the first embodiment, a robot hand 17 may be provided as the tip mounting member instead of the spray nozzle 16. Moreover, in the example shown in FIG. 4, the additional mass 18 is attached. This additional mass 1
The numeral 8 serves to shift the center of gravity from the geometric main axis G by appropriately setting the mass of itself and the distance from the geometric main axis G. In the configuration shown in FIG. 4, the reference axis M orthogonal to the rotation direction A and the geometrical principal axis G is used.
The upper non-deflection point Q is connected to the robot hand 17 and the additional mass 18
When the fiber angle and the stacking configuration are set so as to match the center of gravity J ′ of the combined weight, the flexural vibration does not occur at the start and stop of the rotational movement of the robot hand 17 as in the case described above. .. Therefore, the positioning accuracy of the robot hand 17 when gripping an object (not shown) to be conveyed is improved.

In the second embodiment of the present invention shown in FIG. 5, the robot 20 is of a type that conveys an object to be conveyed 21, and on a rail 22, a moving body 23 constituting an operating body is a driving mechanism (see FIG. (Not shown), the robot arm 24 is reciprocated, and one end of the robot arm 24 is attached to the moving body 23 to form a fixed end 24a, while the other end is a free end 24b and a tip is provided to the free end 24b. A robot hand 25 having a knob-shaped finger as an attachment member is attached. Also,
The robot hand 25 is attached with an additional mass 27 for shifting the center of gravity from the geometrical main axis G. The robot 20 of the second embodiment is a stocker on the upper right side in FIG.
The objects to be transported 21 stocked (not shown) are transported to a predetermined position in a pallet 26 on the left side in the figure.

As shown in FIG. 6, the robot arm 24 has a portion 2 where 300 ° ≦ θ <0 ° and 0 ≦ θ <60 °.
In 4a, one layer having a fiber angle of 0 °, 10 layers having a fiber angle of 30 ° and one layer having a fiber angle of 0 ° are sequentially laminated from the inside. Further, in the portion 24b where 120 ° ≦ θ <240 °, one layer having a fiber angle of 0 °, 10 layers having a fiber angle of −30 ° and one layer having a fiber angle of 0 ° are sequentially arranged from the inside. It is stacked. On the other hand, a portion 24c of 60 ° ≦ θ <120 ° and a portion 24d of 240 ° ≦ θ <300 °
Then, 12 layers having a fiber angle of 0 ° are laminated from the inside.

The length, inner diameter, outer diameter, and other configurations of the robot arm 24 are the same as those of the first embodiment. As described above, the robot arm 24 is a part of the circumferential direction of the robot arm 24 and a part thereof. By making the fiber angles different in a part of the thickness direction of the robot arm 24 as described above, the non-deflection on the reference axis M orthogonal to the moving direction of the robot arm 24 indicated by the arrow B and the geometric main axis G of the robot arm 24 is shown. The point Q is set to coincide with the center of gravity K of the total weight of the robot hand 25, the transported object 21, and the additional mass 27.

Therefore, in the second embodiment, when the robot hand 25 starts moving while holding the transported object 21 or stops the movement, the inertia of the robot hand 25, the transported object 21, and the additional mass 27 is increased. Force acts on the non-deflected point Q,
A load is applied to the non-deflection point Q of the robot arm 24, and the robot arm 24 is bent and twisted. Therefore, the tip of the robot arm 24 does not bend, and therefore flexural vibration can be prevented. Therefore, when the robot arm 24 moves in the direction indicated by the arrow L in the figure and stops on the pallet 26, flexural vibration does not occur, so that the transported object 21 can be moved to the pallet 2 with high accuracy.
It can be placed in place of 6.

The present invention is not limited to the above-mentioned embodiments, but various modifications can be made. For example, in the above embodiment, the additional mass is used only to shift the center of gravity from the geometrical principal axis, but the fiber angle of the robot arm and the stacking configuration are predetermined, and the non-deflection point in that case is used. The position and weight of the additional mass may be set so that the center of gravity coincides with. Further, the material of the robot arm is not limited to the above FRP, and fiber reinforced rubber, fiber reinforced metal, rubber having anisotropy, etc. can be used in combination. Also, the length of the robot arm,
The shape such as the outer diameter and the inner diameter can be arbitrarily determined. Further, the work tip attachment member attached to the free end side of the robot arm is not limited to the above example, and a robot hand including scissor fingers or finger fingers of various known structures, or You may attach the front end attachment member which consists of a suction type robot hand etc. which apply a vacuum force or a magnetic force. Further, it goes without saying that as a work mounting member, a welding gun, various sensors, and other devices that perform various work can be mounted.

<Experimental Example> If at least a part of the robot arm is made of a material having anisotropy, the robot arm will have a reference axis orthogonal to the geometrical main axis even if a load acts on the robot arm. At the tip of the arm, there is a non-deflection point that is a point of action that causes twisting but does not bend, and that the non-deflection point on any reference axis of the robot arm can be set arbitrarily It was confirmed by the experiment.

In the following experiments, the following types 1, 2 and 3
Experiments were performed using a robot arm corresponding to any of the above. Each type of robot arm has 12 layers of prepreg sheets laminated to have an inner diameter ID of 16 mm and an outer diameter OD of 19 mm, and is made of carbon fiber reinforced epoxy resin.

Type 1: Part a1 (0 ° ≦ θ <180 °) (FIG. 7) 12 layers of fiber angle α1 ° laminated part b1 (180 ° ≦ θ <360 °) laminated 12 layers of fiber angle −α1 °

Type 2: Part a2 (30 ° ≦ θ <150 °) (FIG. 8) 12 layers of fiber angle α2 ° laminated Part a2 ′ (210 ° ≦ θ <330 °) laminated 12 layers of fiber angle −α2 ° Part b2 (150 ° ≦ θ <210 °) Part b2 ′ (0 ° ≦ θ <30 ° or 330 ° ≦ θ <36
0 °) Fiber angle β2 ° of 6 layers from inside, fiber angle −β2 of 6 layers
゜

Type 3: Part a3 (30 ° ≦ θ <150 °) (FIG. 9) A layer of 0 ° from the inside is a (6-n / 2) layer, α3
A layer of 0 ° is an n-layer, a layer of 0 ° is a (6-n / 2) layer, part a3 ′ (210 ° ≦ θ <330 °), a layer of 0 ° from the inside is a (6-n / 2) layer, -α3 N layers for 0 ° layers and (6-n / 2) layers for 0 ° layers Part b3 (150 ° ≦ θ <210 °) Part b3 ′ (0 ° ≦ θ <30 ° or 330 ° ≦ θ <36
0 degree) 12 degree layer product

First, as a first experiment, in a robot arm formed by using a material having anisotropy in at least a part thereof, even if a load acts on a reference axis orthogonal to the geometric main axis, the tip of the robot arm An experiment was conducted to confirm that there is a non-deflecting point that is a point of action that causes twisting but does not bend.

The experimental method was as follows. In Experimental Examples 1, 2 and 3, the one end was fixed and the projecting length was 400 mm as shown in FIG. 20, and the jig 31 as shown in FIG. 10 was used. Then, the rod portion 31a of the jig 31 is
The weight 30 of 0 g is hung, and the position of the weight 30 is changed on the reference axis M shown in FIGS. 7 to 9 to change the distance l ₃ of the load position from the geometrical main axis G, and the tip of the robot arm 29. The vertical displacement in the portion, that is, the deflection was examined. Experimental Example 1: α1 = 30 ° in the above type 1 Experimental example 2: α2 = 30 ° and β2 = 0 in the above type 2
Set to 3 ° Experimental Example 3: Set α3 = 30 ° n = 10 in type 3 above

The results of Experimental Example 1, Experimental Example 2 and Experimental Example 3 are shown in FIGS. 11, 12 and 13, respectively. As shown in these diagrams, it can be confirmed that in each experimental example, there is a load position where the deflection at the arm tip is "0", that is, a non-deflection point.

Next, a second experiment was conducted to confirm that the non-deflected point on the reference axis of the robot arm can be set arbitrarily. The second experiment is the following experimental example 4.
From the robot arm of Experimental Example 10. Experimental Example 4 :. Same as type 1 Experimental example 5: Set β2 = 0 ° for type 2 Experimental example 6: Set β2 = 30 ° for type 2 Experimental example 7: Set β2 = 90 ° for type 2 Experimental example 8: Type 3 , Β = 0 °, n = 12 Experimental example 9: type 3 set β = 0 °, n = 10 experimental example 10: type 3 set β = 0 °, n = 8

Experimental methods are as follows: Experimental Example 2 to Experimental Example 10
, Α1, α corresponding to the type to which each experimental example belongs
By changing the angle of 2 or α3 between 0 ° and 90 ° and changing the position of the weight 30 by using the jig 31 shown in FIG. 10 used in the first experiment, the non-deflection point is changed. The origin, that is, the position from the geometrical principal axis G was examined. Experimental results of Experimental Example 4 to Experimental Example 10 are shown in FIGS. 14 to 16, respectively.

As is apparent from the second experiment, in the robot arm according to the present invention, the position of the non-deflection point can be arbitrarily set by changing the material, the fiber angle, the arrangement of the parts that make the fiber angle different, and the like. Therefore, the position of the non-deflected point of the robot arm tip is added to the center of gravity of the tip attaching member or the tip attaching member and the center of gravity of the transported object held by the tip attaching member and the weights of the attached additional weights. It can match the center of gravity of the weight.

[0049]

As is apparent from the above description, since the robot arm of the present invention is made of a material having anisotropy in at least a part thereof, even if a load is applied, only the end of the arm is twisted. There is a point of action that does not cause bending, that is, a non-deflecting point, and this non-deflecting point can be set at an arbitrary position. Therefore, by setting the position of the non-deflection point of the robot arm tip to coincide with the center of gravity of the tip mounting member or the center of gravity of the tip mounting member and the transported object held by this tip mounting member, parallel movement or rotational movement It is possible to prevent the robot arm from being bent by the inertial force of the tip mounting member or the transported object at the time of starting or stopping. Further, in the present invention, the non-deflection point and the center of gravity can be more easily coincided with each other by changing the position of the center of gravity by attaching the additional mass to the tip attaching member.

Since the robot arm according to the present invention does not cause flexural vibration as described above, it is necessary to adjust the acceleration / deceleration of the robot arm at the start or end of rotational movement or linear movement in order to prevent flexural vibration. It can be moved to a predetermined position accurately and quickly. Therefore, according to the present invention, various advantages such as simplification and weight reduction of the control mechanism and cost reduction can be achieved without increasing the rigidity of the robot arm.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a robot arm.

3A is a sectional view taken along line III-III in FIG. 2,
(B) And (C) is a schematic diagram showing a fiber angle.

FIG. 4 is a schematic partial perspective view showing a case where a robot hand is attached to the robot arm of the first embodiment.

FIG. 5 is a schematic view showing a second embodiment.

FIG. 6 is a sectional view showing a robot arm according to a second embodiment.

FIG. 7 is a cross-sectional view showing type 1.

FIG. 8 is a cross-sectional view showing a type 2.

FIG. 9 is a cross-sectional view showing a type 3.

FIG. 10 is a schematic perspective view showing a method of applying a load in an experiment.

FIG. 11 is a diagram showing the results of the first experiment.

FIG. 12 Same as above

FIG. 13 Same as above

FIG. 14 is a diagram showing the results of the second experiment.

FIG. 15 Same as above

FIG. 16 Same as above

FIG. 17 is a schematic view showing a usage example of a conventional robot arm.

FIG. 18 is a schematic perspective view of a robot arm for explaining the principle of the present invention.

FIG. 19 (A) is a cross-sectional view of a robot arm, (B).
And (C) is a schematic view showing a fiber angle.

FIG. 20 is a schematic view showing a state in which the robot arm is cantilevered.

FIG. 21 is a diagram showing the deflection when a load is applied to the reference shaft.

FIG. 22 is a schematic diagram showing deformation when a load is applied to a non-deflected point.

FIG. 23 is a diagram showing the movement of the non-deflecting point when the fiber angle is changed.

[Explanation of symbols]

 15,24 Robot arm, 16,25,27 Tip mounting member 18,27 Additional mass 21 Conveyed object J, J ', K Center of gravity G Geometric main axis Q Non-deflection point

Claims (4)

[Claims] 1. A robot arm having a fixed end at one end connected to an actuating body and a free end at the other end connected to a tip end mounting member such as a robot hand for gripping a transported object or a gun spray for working. , A material having anisotropy at least in part is used, and at a point on the axis orthogonal to the moving direction of the robot arm, even if a load in the moving direction acts, a twist occurs at the tip of the robot arm. A robot arm characterized in that a non-deflection point, which is a point of action that does not exist, is set so as to coincide with the center of gravity of the tip mounting member. 2. A robot arm having a fixed end at one end connected to an operating body and a free end at the other end connected to a robot hand for gripping an object to be conveyed or a tip attachment member such as a gun spray for working. , A material having anisotropy at least in part is used, and at a point on the axis orthogonal to the moving direction of the robot arm, even if a load in the moving direction acts, a twist occurs at the tip of the robot arm. A robot arm characterized in that a non-deflection point, which is a point of action that does not occur, coincides with the center of gravity of the tip mounting member and the object to be conveyed held by the tip mounting member. 3. A non-flexible fiber-reinforced composite material is used as a material for forming the robot arm, wherein the fiber angle of the fiber-reinforced composite material is partially different in the circumferential direction and at least partially in the thickness direction. The robot arm according to claim 1 or 2, wherein the point is set at the predetermined position described above. 4. The tip mounting member is arranged so that the non-deflection point coincides with a center of gravity of the tip mounting member or a center of gravity of the tip mounting member and a conveyed object held by the tip mounting member. The robot arm according to any one of claims 1 to 3, wherein an additional mass is attached.