Patent Application
20190033481
Embodiments described herein relate generally to a proximity sensor apparatus and a robot arm mechanism.
Conventionally, an articulated robot arm mechanism has been used in various fields such as an industrial robot. A linear extension and retraction mechanism that has been put to practical use by the inventors can eliminate the need for an elbow joint from a vertical-articulated-type robot arm mechanism, and eliminates the need for a safety fence to make it possible to install a robot in the vicinity of a worker, and an environment in which robots and workers cooperate with one another has become realistic.
On the other hand, it is important to secure high safety since robot arm mechanisms are disposed in the vicinity of the workers. Consequently, many robots are each equipped with a proximity sensor for each movable section. A proximity sensor has a relatively short sensitivity distance, so that in order to decrease a nonsensitive region, a large number of proximity sensors have been required with positions and sensitivity directions changed.
[Patent Literature 1] Japanese Patent No. 5435679
An object of the present invention is to provide a proximity sensor apparatus suitable for a robot arm mechanism, and having a simple structure and a large detection region.
A proximity sensor apparatus according to a present embodiment includes a detection electrode that forms an electrostatic capacitance between the detection electrode and an object to be detected that approaches the detection electrode, a detection section that detects the electrostatic capacitance, and a determination section that determines approach of the object to be detected to the detection electrode based on the detected electrostatic capacitance, wherein the detection electrode includes a base that curves into a U-shape or a C-shape, the detection electrode that is disposed on a front surface of the base, and curves along the front surface of the base, and a guard that is disposed on a back surface of the base, and curves along the back surface of the base.
Hereinafter, a proximity sensor apparatus according to a present embodiment will be described with reference to the accompanying drawings. In the following explanation, a robot arm mechanism including the proximity sensor apparatus according to the present embodiment will be described as an example. In the robot arm mechanism, one joint of a plurality of joints is constituted of a linear extension and retraction mechanism. Note that one of features of the proximity sensor apparatus according to the present embodiment lies in that a detection electrode thereof is formed by a conductive wire. This enhances the degrees of freedom of wiring of the detection electrode, and realizes implementation of the electrode to a complicated structure. Consequently the proximity sensor apparatus according to the present embodiment may be mounted to structures other than the robot arm mechanism, for example, an automobile and the like. In the following description, the same reference numerals denote components having substantially identical functions and structures, and the repeated description thereof is made only when necessary.
The robot arm mechanism includes a base 1, a turning section (support section) 2, a rising and lowering section 4, an arm section 5 and a wrist section 6. The turning section 2, the rising and lowering section 4, the arm section 5 and the wrist section 6 are arranged in order from the base 1. A plurality of joints J1, J2, J3, J4, J5 and J6 are arranged in order from the base 1. The turning section 2 which forms a cylindrical body is typically installed vertically on the base 1. The turning section 2 houses the first joint J1 as a turning rotation joint. The first joint. J1 includes an axis of torsional rotation RA1. The axis of rotation RA1 is parallel to a vertical direction. The turning section 2 has a lower frame 21 and an upper frame 22. One end of the lower frame 21 is connected to a fixed section of the first joint. J1. The other end of the lower frame 21 is connected to the base 1. The lower frame 21 is covered with a housing 31 in a cylinder shape. The upper frame 22 is connected to a rotating section of the first joint J1, and axially rotates on the axis of rotation RA1. The upper frame 22 is covered with a housing 32 in a cylinder shape. The upper frame 22 rotates with respect to the lower frame 21 in accordance with the rotation of the first joint J1, and thereby the arm section 5 turns horizontally. In an internal hollow of the turning section 2 forming the cylindrical body, a first and second piece strings 51 and 52 of the third joint J3 as a linear extension and retraction mechanism that will be described later are housed.
The rising and lowering section 4 that houses the second joint J2 as a rising and lowering rotation joint is installed on an upper part of the turning section 2. The second joint J2 is a bending rotation joint. An axis of rotation RA2 of the second joint J2 is perpendicular to the axis of rotation RA1. The rising and lowering section 4 has a pair of side frames 23 as a fixed section (support body) of the second joint J2. The pair of side frames 23 are connected to the upper frame 22. The pair of side frames 23 are covered with a cover 33 in a saddle shape. A cylindrical body 24 as a rotating section of the second joint. J2, which is also used as a motor housing, is supported by the pair of side frames 23. A sending-out mechanism 25 is attached to a circumferential surface of the cylindrical body 24. The sending-out mechanism 25 is covered with a cover 34 in a cylinder shape. A gap between the saddle-shaped cover 33 and the cylindrical cover 34 is covered with a U-shaped pleated cover 14 having a U-shaped section. The U-shaped pleated cover 14 extends and retracts by following rising and lowering motions of the second joint 42.
The sending-out mechanism 25 holds a drive gear 56, a guide roller 57 and a roller unit 58. The sending-out mechanism 25 rotates in accordance with the axial rotation of the cylindrical body 24, and the arm section 5 supported by the sending-out mechanism 25 rises and lowers up and down.
The third joint. J3 is provided by the linear extension and retraction mechanism. The linear extension and retraction mechanism includes a structure that is newly developed by the inventors, and is clearly distinguished from a so-called conventional linear motion joint from the viewpoint of a movable range. The arm section 5 of the third joint J3 is bendable, but when the arm section 5 is sent out forward from the sending-out mechanism 25 at a root of the arm section 5 along a center axis (center axis of extension and retraction RA3), bending of the arm section 5 is restricted, and linear rigidity is ensured. When the arm section 5 is pulled backward, bending is restored. The arm section 5 has the first piece string 51 and the second piece string 52. The first piece string 51 is constituted of a plurality of first pieces 53 that are connected to be bendable. The first piece 53 is formed into a substantially flat-plate shape. The first pieces 53 are bendably connected with hinge sections in spots at end portions. The second piece string 52 is constituted of a plurality of second pieces 54. The second piece 54 is formed into a groove-shaped body with a U-shaped cross section or a tubular body with a hollow-square-shaped cross section. The second pieces 54 are bendably connected with hinge sections in spots at bottom plate end portions. Bending of the second piece string 52 is restricted in a position where end surfaces of side plates of the second pieces 54 abut on one another. In that position, the second piece string 52 is arranged linearly. The leading first piece 53 of the first piece string 51 and the leading second piece 54 of the second piece string 52 are connected by a head piece 55. For example, the head piece 55 has a shape obtained by combining the first piece 53 and the second piece 54.
The first and second piece strings 51 and 52 are pressed against each other and overlapped with each other by a roller 59 when the first and second piece strings 51 and 52 pass through the roller unit 58 of the sending-out mechanism 25. By being overlapped with each other, the first and second piece strings 51 and 52 exhibit linear rigidity, and constitute the columnar arm section 5. Behind the roller unit 58, the drive gear 56 is disposed with the guide roller 57. The drive gear 56 is connected to a motor unit not illustrated. The motor unit generates power for rotating the drive gear 56. As will be described later, a linear gear is formed along a connection direction, in a center of a width of an inner surface of the first piece 53, that is, a surface at a side where the first piece 53 is overlapped with the second piece 54. Linear gears that are adjacent to one another when the plurality of first pieces 53 are aligned linearly are connected to one another linearly, and constitute a long linear gear. The drive gear 56 is engaged with the linear gear of the first piece 53 which is pressed by the guide roller 57. The linear gears which are connected linearly constitute a rack and pinion mechanism with the drive gear 56. When the drive gear 56 rotates forward, the first and second piece strings 51 and 52 are sent out forward from the roller unit 58. When the drive gear 56 rotates backward, the first and second piece strings 51 and 52 are pulled backward of the roller unit 58. The first and second piece strings 51 and 52 which are pulled back are separated from each other between the roller unit 58 and the drive gear 56. The first and second piece strings 51 and 52 which are separated respectively return to bendable states. The first and second piece strings 51 and 52 which return to bendable states both bend in a same direction (inward), and are vertically housed in the turning section 2. At this time, the first piece string 51 is housed in a state in which the first piece string 51 is substantially aligned substantially parallel to the second piece string 52.
The wrist section 6 is attached to a tip of the arm section 5. The wrist section 6 is equipped with fourth to sixth joints J4 to J6. The fourth to sixth joints J4 to J6 respectively include axes of rotation RA4 to RA6 which are orthogonal three axes. The fourth joint J4 is a torsional rotation joint that rotates on the fourth axis of rotation RA4 which substantially matches the center axis of extension and retraction RA3, and by rotation of the fourth joint J4, an end effector is swingably rotated. The fifth joint J5 is a bending rotation joint that rotates on the fifth axis of rotation RA5 disposed perpendicularly to the fourth axis of rotation RA4, and by rotation of the fifth joint J5, the end effector is pivoted forward and backward. The sixth joint J6 is a torsional rotation joint that rotates on the sixth axis of rotation RA6 disposed perpendicularly to the fourth axis of rotation RA4 and the fifth axis of rotation RA5, and the end effector is axially rotated by rotation of the sixth joint J6.
The fourth joint J4 forms a cylindrical body with the axis of rotation RA4 as a center line, and a fixed section 61 of the fifth joint J5 which forms a cylindrical body is attached to a tip of the fourth joint J4 so that the cylindrical body of the fourth joint J4 and a center line are orthogonal to each other. An arm 62 in a U-shape or C-shape is rotatably supported at the fixed section 61 of the fifth joint J5 in a state in which the arm 62 is placed across both ends of the fixed section 61. A cylindrical body 63 that forms the fixed section of the sixth joint J6 is attached to an inside of a tip of the arm 62.
A sensor main body 11 of a proximity sensor apparatus 10 that is typically in a U-shape is mounted to the arm 62 in the U-shape of the wrist section 6 in such a manner as to cover an outer circumference of the arm 62. Note that it is not denied that the sensor main body 11 is in a C-shape. When an object to be detected which is typically a finger, an arm, a body or the like of a worker (human being) approaches the sensor main body 11 of the proximity sensor apparatus 10, the proximity sensor apparatus 10 detects the approach. Details of the proximity sensor apparatus 10 will be described later.
The end effector is attached to an adapter 7 provided at a lower part of a rotating section of the sixth joint. J6 of the wrist section 6. The end effector is a section having a function of directly acting on an object to be worked (a work) by a robot, and various tools exist in accordance with tasks, such as a holding section, a vacuum suction section, a nut fastening tool, a welding gun, and a spray gun, for example. The end effector is moved to a given position by the first, second and third joints J1, J2 and J3, and is placed in a given posture by the fourth, fifth and sixth joints J4, J5 and J6. In particular, a length of an extension and retraction distance of the arm section 5 of the third joint J3 enables the end effector to reach an object in a wide range from a position close to the base 1 to a position far from the base 1. In the third joint J3, the linear extension and retraction motions and the length of the extension and retraction distance realized by the linear extension and retraction mechanism constituting the third joint J3 are characteristics that differ from the conventional linear motion joint.
As shown in
As further shown in
As shown in
When a plurality of, for example, the two wires 13-1 and 13-2 that are respectively wired in rectangular shapes and electrically separated from each other are arranged in the U-shape as shown in
In this way, the sensor main body of the proximity sensor apparatus according to the present embodiment includes the detection electrode in a U-shape, and therefore the sensor main body can have sensitivity to approaches from many directions of not only a front but also a left or right to the detection electrode. The proximity sensor apparatus can be realized with a very simple structure as compared with the conventional structure in which a number of sensor apparatuses, at least a number of detection electrodes are mounted to the wrist section and the like while the positions and directions are changed. In addition, in the present embodiment, the detection electrode is implemented with wiring of the wire, and simplification of the structure, reduction in the number of assembly steps, and reduction in weight of the sensor main body can be realized. Further, it is not necessary to provide capacitance detection circuits and the determination sections individually to a number of detection electrodes as in the conventional sensor apparatus, and approaches from many directions can be detected with the capacitance detection circuit and the determination section of one system.
In the above, the detection electrode can have sensitivity to approaches in the three directions in total that are the front and both left and right sides by wiring the wire into a U-shape or a C-shape. However, as illustrated in
Further, as illustrated in
Further, one of the important features of the detection electrode 13 is that the detection electrode 13 is constituted of a conductive wire. A conductive wire has a higher degree of freedom of a shape thereof than a plate-shaped or a foil electrode. Accordingly, it is possible to wire the conductive wire by winding the conductive wire in a spiral shape around an outer circumference of various structures that are concerned about contact with an outside, for example, an arm 14 as illustrated in
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
10 . . . Proximity sensor apparatus, 11 . . . Sensor main body, 13 . . . Detection electrode, 14 . . . Base, 15 . . . Guard
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-066896 | Mar 2016 | JP | national |
This application is continuation application of International Patent Application No. PCT/JP2017/012211 filed on Mar. 26, 2017, which is based upon and claims the benefit of priority from the prior Japanese Patent. Application No. 2016-066896, filed Mar. 29, 2016 the entire contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2017/012211 | Mar 2017 | US |
| Child | 16147259 | US |
