JP2010125531A - Robot arm and robot equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a robot arm which can effectively mitigate external stress while assuming a thin outer covering structure. <P>SOLUTION: The robot arm has an external skeletal frame and a flexible outer covering which covers the external skeletal frame and contains a plurality of holes formed therein; wherein a first width of the holes, which extends in parallel to a thickness direction of the outer covering, is larger than a second width thereof which extends perpendicularly to the thickness direction of the outer covering. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a robot arm having a skin that can relieve external stress.

  In the near future, support robots and service robots engaged in the field of medical care, light work in the home, and high-load work in the primary industry will be popularized to compensate for the labor shortage accompanying the declining birthrate and aging population. It is predicted to go. Robots that play an active role in this market include communication technology that interacts with people, sensor technology that constantly grasps the position and status of surrounding objects, hand technology that grips objects of various shapes, and the same operations and tasks as people. Various elemental technologies to contribute to humans are required, such as manipulation technology that realizes the above, and battery technology that can operate stably.

Among them, for example, Patent Document 1 and Patent Document 2 have proposed robots equipped with means for reducing external stress.
JP-A-9-254078 JP 2004-283975 A

In the case of a robot that performs an operation such as carrying an object at a care site, the robot arm requires a torque for lifting an object of about 2 kg, and therefore an actuator such as a motor or a speed reducer is built in the robot arm. In order to hold them, the robot arm is composed of an exoskeleton frame such as metal or reinforced resin. As the robot arm is lighter in weight, control during operation can be simplified, and as the arm diameter is smaller, the range of motion of the arm becomes wider. Therefore, it is desirable that the robot arm be light and small for smooth operation.
For this reason, it is necessary to make the outer skin covering the exoskeleton frame as thin as possible, but it is considered effective to increase the thickness of the outer skin in order to relieve the stress applied from the outside. The conventional technology cannot solve this conflicting requirement.

  An object of the present invention is to provide a robot arm that can realize both effective relaxation of external stress and a thin outer skin structure that cannot be achieved in the conventional example.

In order to achieve the above object, the present invention comprises the following arrangement.
The invention according to claim 1 includes an exoskeleton frame and a flexible outer skin that covers the exoskeleton frame and has a plurality of holes formed therein, and the holes have a thickness of the outer skin. The robot arm has a first width extending in a direction parallel to the direction larger than a second width extending in a direction perpendicular to the thickness direction of the outer skin.
According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, the first width is 1.2 times or more of the second width.
According to a third aspect of the invention, in addition to the structure of the second aspect of the invention, the outer skin is composed of an upper layer and a lower layer made of flexible materials of different materials, and the plurality of holes are in the upper layer and the lower layer, respectively. Is formed.
According to a fourth aspect of the present invention, in addition to the configuration of the third aspect of the invention, the thickness of the outer skin is 5 mm or less, and the flexible material is a foamed resin, rubber or rubber having a compressive elastic modulus of 0.1 MPa to 3 MPa. It is a gel.
According to a fifth aspect of the present invention, in addition to the structure of the third or fourth aspect, the lower layer is a rubber sponge having a density of 0.3 g / m ³ or less.
In addition to the structure of any one of the third to fifth aspects, the invention described in claim 6 has different cross-sectional shapes between the holes formed in the upper layer and the holes formed in the lower layer.
According to a seventh aspect of the invention, in addition to the configuration of any of the third to sixth aspects, one end of each of the plurality of holes provided in the upper layer is opened.
The invention according to claim 8 is a movable robot provided with the robot arm according to any one of claims 1 to 7.

According to the first to seventh aspects of the invention, since the outer skin has a plurality of vertically long holes in the thickness direction, when an external stress is applied to the outer skin, the holes are deformed and the stress is changed in the lateral direction ( Can be dispersed in a direction perpendicular to the thickness of the outer skin. Therefore, even a thin skin can satisfy the demand for external stress relaxation.
According to the eighth aspect of the invention, it is possible to realize a lightweight robot that exhibits the above-described effects.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings in the present embodiment, some elements are schematically shown in order to facilitate understanding of the invention. In a plurality of embodiments in this column, the description may be omitted by giving the same reference numerals.

  FIG. 1 shows a side sectional view and a top view showing an outer skin structure of a robot arm according to an embodiment of the present invention. For the understanding of the invention, a part of the robot arm is extracted and schematically shown in FIG. 1, but it will be possible to implement the invention with reference to this drawing and the following description. . The robot arm can be controlled and operated by a known method.

  As shown in FIG. 1, a flexible outer skin 2 is formed on an aluminum frame 1 which is an exoskeleton of a robot arm. The outer skin 2 includes a lower layer 3 and an upper layer 4, and the lower layer 3 and the upper nest 4 are made of different flexible materials. In the present embodiment, the lower layer 3 is made of a natural rubber rubber sponge, and the lower layer 4 is made of silicone rubber. A plurality of holes 31 are formed in the lower layer 3, and a plurality of holes 41 are formed in the upper layer 4. In the holes 31 and 41, the first width extending in the direction d1 parallel to the thickness direction of the outer skin 2 is larger than the second width extending in the direction d2 perpendicular to the thickness direction of the outer skin. That is, a vertically long hole is formed in the outer skin 2 in the thickness direction. Since the upper end of the air hole 41 is opened, it can be said that the air hole 41 has an uneven shape.

  Since a plurality of vertically long holes are provided in the thickness direction of the lower layer 3 and the upper layer 4 of the outer skin 2, when external stress is applied to the outer skin, the holes are deformed and the stress is changed in the lateral direction (perpendicular to the thickness of the outer skin Can be dispersed in any direction). Furthermore, since the holes are formed, the weight of the outer skin 2 is reduced, which can contribute to the weight reduction of the robot arm. In the present embodiment, a form in which holes are formed in both the lower layer 3 and the upper layer 4 is shown. However, even in a configuration in which a vertically long hole is formed in any of the outer skins 2, the operation of the present invention is performed. There is an effect.

  In this embodiment, the outer skin 2 of the robot arm is formed of two layers of a lower layer 3 made of a rubber sponge having a thickness of 5 mm or less and an upper layer 4 made of silicone rubber, and includes a hole 31 in the lower layer 3 and a hole 41 in the upper layer 4. The aspect ratio is set to be a portrait length of 1.2 or more. The cross-sectional shape of the hole 31 is elliptical.

  Since the aluminum frame 1 that is an exoskeleton of the robot arm has a complicated shape, it is formed of an aluminum casting (AC4C), and the surface thereof is subjected to chemical conversion treatment for corrosion prevention.

  A natural rubber rubber sponge sheet having a thickness of 2 mm is cut into an appropriate shape and pasted on the surface of the chemically treated frame 1. The rubber sponge sheet is provided with holes having an aspect ratio of 1.2 or more.

Here, the manufacturing method of the rubber sponge sheet | seat which has a vertically long hole in this embodiment is demonstrated. Natural rubber, which is a raw material, and additives such as a foaming agent, a crosslinking agent, and a softening agent are mixed in a mold for molding, and cured and foamed at a high pressure of 150 ° C. so as not to be completely cured. Next, it is secondarily cured in a state where pressure is applied from the side by a heat press, and a rubber sponge sheet having vertically long holes is formed. The obtained rubber sponge sheet had a specific gravity of 0.3 g / m ³ and a compression modulus of 0.1 Pa.

Next, the frame 1 to which the rubber sponge sheet was attached was placed in a resin mold, and flexible silicone rubber (KE1416 manufactured by Shin-Etsu Chemical) was poured into the mold for casting. Concavities and convexities are formed in advance on the mold surface. In the present embodiment, three types of irregularities having aspect ratios of 1, 1.2, and 2 are formed on the three types of mold surfaces. Thus, the upper layer 4 made of silicone rubber having a thickness of 3 mm and a hole depth of 2 mm was formed. The resulting silicone rubber layer had a specific gravity of 1.19 g / m ³ and a compression modulus of 0.25 MPa.

  Here, for comparison experiments, rubber sponge sheets according to the present embodiment were produced with aspect ratios of 1.2 (Embodiment 1) and 2 (Embodiment 2). A rubber sponge sheet having pores with an aspect ratio of 1 was produced. Moreover, what formed the upper layer with the silicone elastomer whose compression elastic modulus is 0.08 MPa as the comparative example 2, and the polyurethane elastomer whose compression elastic modulus is 3.5 MPa as the comparative example 3 was prepared. In addition, about the structure of Comparative Examples 1 thru | or 3, it is the same as that of the structure of this embodiment about the structure except having specified in this column.

  The robot arm covered with the outer skin according to the present embodiment as described above and the outer skin according to Comparative Examples 1 to 3 is attached to the robot, and the robot arm is operated so that the impact energy is 2 J. I collided. A load cell was attached to the surface behind the collision surface of the iron plate, and the impact force at the time of collision was measured. And the impact relaxation rate of each form was calculated | required compared with the case where the impact force at the time of making a metal frame without an outer skin collide directly with a collision surface is set to 100. FIG. The results are shown in Table 1.

  As is apparent from Table 1, according to this embodiment in which the compression modulus is 0.25 and the aspect ratio of the holes is 1.2 or more, the aspect ratio of the holes is 2 times or more compared to Comparative Example 1 in which the aspect ratio is 1. The impact relaxation was obtained. Further, Comparative Examples 2 and 3 having a compressive modulus of 0.1 MPa or less and 3.0 MPa or more also had a small impact relaxation effect. Therefore, as shown in the determination column of Table 1, it was confirmed that the preferred robot arm is the configuration shown in the first and second embodiments.

  In the present embodiment, an aluminum casting is used for the frame, but a light and highly rigid material such as a magnesium alloy or a resin reinforced with fibers may be used. In addition, although a natural rubber rubber sponge is used for the lower layer of the outer skin, a rubber sponge having high elasticity such as silicone or norbornene rubber may be used.

  In the present embodiment, castable silicone rubber is used for the upper layer of the outer skin, but soft resins such as various elastomers and urethane resins may be used. However, since the lower rubber sponge cuts and bonds the sheets, it is desirable to use a low-cost cast resin that can be molded in the upper layer in order to improve the appearance by hiding the joint.

  In order to relieve external stress, the thickness of the outer skin is desirably 3 mm or more. In addition, when forming an outer skin only with a rubber sponge instead of two layers, the film thickness is appropriately set in consideration of the compression elastic modulus. In addition, when the outer skin is formed only of silicone rubber having a high compression elastic modulus, it is necessary to consider that the weight of the outer skin becomes heavy because the specific gravity is large.

According to this embodiment, since the outer skin is provided with a plurality of vertically long holes in the thickness direction, when an external stress is applied to the outer skin, the holes are deformed and the stress can be dispersed in the lateral direction. Therefore, even a thin skin can satisfy the demand for external stress relaxation. Furthermore, when the outer skin thickness is 5 mm or less, the outer skin of the robot arm that is thin and soft and relieves external stress can be obtained by setting the compression elastic modulus of the flexible material constituting the outer skin to 0.1 MPa or more and 3 MPa or less. . In order to give the user a sense of security with respect to the outer skin, the compression elastic modulus is preferably softness of 0.1 MPa to 0.5 MPa. Further, by forming the lower layer of the outer skin with a rubber sponge having a density of 0.3 g / m ³ or less, it is possible to reduce the weight of the outer skin and to obtain vertically long holes having an aspect ratio of 1.2 or more.

  The robot arm according to the present embodiment is suitable for a movable robot that conveys an object.

Side sectional view and top view of a robot arm showing an embodiment of the present invention

Explanation of symbols

1 Frame 2 Skin 3 Lower layer 31 Hole 4 Upper layer 41 Hole

Claims (8)

An exoskeleton frame,
Covering the exoskeleton frame, and comprising a flexible outer skin in which a plurality of pores are formed;
The robot arm according to claim 1, wherein a first width extending in a direction parallel to a thickness direction of the outer skin is larger than a second width extending in a direction perpendicular to the thickness direction of the outer skin.   The robot arm according to claim 1, wherein the first width is 1.2 times or more of the second width.   3. The robot arm according to claim 2, wherein the outer skin is composed of an upper layer and a lower layer made of flexible materials made of different materials, and the plurality of holes are formed in the upper layer and the lower layer, respectively.   4. The robot arm according to claim 3, wherein the thickness of the outer skin is 5 mm or less, and the flexible material is a foamed resin, rubber or gel having a compressive elastic modulus of 0.1 MPa or more and 3 MPa or less. 5. The robot arm according to claim ³ , wherein the lower layer is a rubber sponge having a density of 0.3 g / m ³ or less.   The robot arm according to any one of claims 3 to 5, wherein a hole formed in the upper layer and a hole formed in the lower layer have different cross-sectional shapes.   7. The robot arm according to claim 3, wherein one end of each of the plurality of holes provided in the upper layer is opened.   A movable robot provided with the robot arm according to claim 1.