Position detection system and actuator

Abstract

A position detection system (1) is provided with: a primary encoder (15) that detects the position of a motor shaft (13) of a motor (10); a secondary encoder (25) that detects the position of the output shaft (23) of the decelerator (20); and additional speed reducers (30, 30 ') disposed between the output shaft (23) and the secondary encoder (25), the speed reduction ratio of the additional speed reducers being set so that a rotating disk (25A) for the secondary encoder rotates within one circle in the entire region of the movable range of the machine provided with the motor and the speed reducers.

Description

Technical Field

[0001] The present disclosure relates to a position detection system and an actuator. Background Art

[0002] The actuator includes a servo motor and a reducer connected to each other. A primary encoder is connected to the motor shaft of the servo motor to detect the absolute position of the motor shaft within one rotation and the total number of rotations of the motor shaft. Similarly, a secondary encoder is connected to the output shaft of the reducer to detect the absolute position of the output shaft within one rotation and the total number of rotations of the output shaft (for example, refer to Japanese Patent Publication No. 2007-113932). The information detected by each encoder is stored in a memory.

[0003] In certain cases, for example, when the servo motor stops and the output shaft of the reducer rotates due to inertia, as long as the output shaft of the reducer rotates within one revolution, the total number of rotations of the primary encoder can be obtained based on the absolute position information of the secondary encoder. In this case, each encoder can continue to be used without using an additional battery.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-113932 Summary of the invention

[0007] Problems to be solved by the invention

[0008] The aforementioned actuator is sometimes assembled in a specific machine, such as a robot, having a shaft portion capable of rotating more than ±360° and less than ±720° (more than one turn and less than two turns). When the shaft portion rotates more than one turn and less than two turns, additional batteries are required to continue using each encoder.

[0009] Therefore, an encoder that can be continuously used over the entire movable range of the shaft portion without requiring an additional battery is desired.

[0010] Means for solving problems

[0011] According to a first embodiment of the present disclosure, a position detection system is provided, characterized in that it comprises: a primary encoder, which detects the position of a motor shaft of a motor; a secondary encoder, which detects the position of an output shaft of a reducer combined with the motor; and an additional reducer, which is arranged between the output shaft of the reducer and the secondary encoder, and the reduction ratio of the additional reducer is set to within one rotation of a rotating disk for the secondary encoder in the entire area of ​​the movable range of the machine having the motor and the reducer.

[0012] Furthermore, according to another embodiment, an actuator is provided, characterized in that it comprises: a motor; a reducer combined with the motor; a primary encoder that detects the position of the motor shaft of the motor; a secondary encoder that detects the position of the output shaft of the reducer; and an additional reducer that is arranged between the output shaft of the reducer and the secondary encoder, the reduction ratio of the additional reducer being set so that a rotating disk for the secondary encoder rotates within one revolution in the entire area of ​​the movable range of the machine having the motor and the reducer.

[0013] The objects, features, and advantages of the present disclosure will become more apparent from the following description of the embodiments in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic side view of the position detection system according to the first embodiment of the present disclosure.

[0015] Figure 2 yes Figure 1 The front view of the additional reducer is shown.

[0016] Figure 3 This is a schematic side view of a position detection system according to a second embodiment of the present disclosure.

[0017] Figure 4 Yes means Figure 3 FIG. 1 is a diagram of a modified example of . DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In all the drawings, corresponding components are denoted by common reference symbols.

[0019] Figure 1 1 is a schematic side view of a position detection system according to a first embodiment of the present disclosure. The position detection system 5 is assembled to a machine 3 having an axis, such as a joint axis of a robot 3. Hereinafter, a case where the position detection system 5 is assembled to the robot 3 will be described, but the same is true for a case where the position detection system 5 is assembled to other machines 3 having an axis, such as a machine tool.

[0020] exist Figure 1In the figure, the actuator 6 arranged on the connecting rod 1 includes: a motor 10 connected to each other, such as a servo motor; and a reducer 20 connected to the motor shaft 13 of the motor 10. The motor 10 includes a rotor 12 that rotates integrally with the motor shaft 13 and a stator 11 that is arranged in a manner to surround the rotor 12. The front end of the output shaft 23 of the reducer 20 is connected to the connecting rod 2. Therefore, the actuator 6 composed of the motor 10 and the reducer 20 causes the connecting rod 2 to rotate relative to the connecting rod 1 within a prescribed range of motion to perform positioning control. In addition, the reduction ratio of the reducer 20 is, for example, 1:50.

[0021] The motor shaft 13 is, for example, a hollow shaft, and a primary encoder 15 is mounted at its rear end. The primary encoder 15 is, for example, an incremental encoder, and outputs A-phase, B-phase, and Z-phase signals. The output signal is detected by the detection unit 16, and the absolute position PA1 and the total number of rotations PB1 of the motor shaft 13 within one rotation are detected by a known method. The detected information is stored in the memory 7, for example, a volatile memory.

[0022] The output shaft 23 extends toward the motor 10 through the hollow motor shaft 13, and the rear end of the output shaft 23 is connected to the secondary encoder 25 via the additional reducer 30 described later. The secondary encoder 25 is, for example, an incremental encoder, and outputs A-phase, B-phase, and Z-phase signals. The output signal is detected by the detection unit 26, and the absolute position PA2 and the total number of rotations PB2 of the output shaft 23 within one rotation are detected by a known method. The detected information is stored in the memory 7, such as a volatile memory. In addition, as is known, the primary encoder 15 and the secondary encoder 25 have rotating disks 15A and 25A, respectively.

[0023] The information stored in the memory 7 is stored for a certain period of time by a battery 8, such as a button battery or a capacitor. Figure 1 In the embodiment, the primary encoder 15 and the secondary encoder 25 are provided with a common memory 7 and a common battery 8. However, the primary encoder 15 and the secondary encoder 25 may be provided with separate memories and batteries, respectively.

[0024] The information stored in the memory 7 is provided to the controller 9 for controlling the machine 3. The controller 9 may also be an LSI equipped with the encoders 15 and 25. The controller 9 drives and controls the motor 10 based on the information provided, and performs a positioning operation for positioning the connecting rod 2 at a target position relative to the connecting rod 1. In addition, the built-in brake 50 provided on the outer surface side of the motor shaft 13 is activated according to the instruction of the controller 9, and the motor shaft 13 is braked. In addition, the controller 9 also plays a role in energizing the primary encoder 15 and the secondary encoder 25 when the machine 3 having the connecting rods 1 and 2 is working.

[0025] Figure 2 yes Figure 1 The additional speed reducer 30 in the first embodiment is a planetary gear device. In this case, the additional speed reducer 30 can be prepared at a relatively low cost. However, other speed reduction mechanisms other than the planetary gear device, for example, a wave gear speed reducer or a cycloid speed reducer can also be used as the additional speed reducer 30.

[0026] Figure 2 The additional speed reducer 30 shown in the figure has: a sun gear 19 fixed to the rear end of the motor shaft 13; a plurality of, for example, four, planetary gears 32 engaged with the sun gear 19; an outer ring 31 surrounding the plurality of planetary gears 32; and a planetary carrier 35 rotatably engaged with the central axes of the plurality of planetary gears 32. Figure 1 It can be seen that the shaft portion extending from the center of the planetary carrier 35 is coaxial with the motor shaft 13 of the motor 10 and the output shaft 23 of the speed reducer 20 , and is connected to the rotating disk 25A of the secondary encoder 25 .

[0027] according to Figure 1 It can be seen that the additional speed reducer 30 is arranged between the output shaft 23 of the speed reducer 20 and the secondary encoder 25. The actuator 6 composed of the motor 10 and the speed reducer 20 is sometimes arranged in a specific machine 3, such as a robot 3, having a shaft portion 23 capable of rotating at a range of more than ±360° and less than ±720° (more than one turn and less than two turns).

[0028] In such a case, the reduction ratio of the additional reduction gear 30 is set so that the rotary disk 25A for the secondary encoder 25 makes one rotation within the entire movable range of the machine 3 including the motor 10 and the reduction gear 20 .

[0029] In one embodiment, the outer diameter D1 of the sun gear 19 is set to 16 mm, and the inner diameter D2 of the outer ring 31 is set to 26 mm. The speed of the output shaft 23 is equal to the speed V1 of the sun gear 19, and the speed V2 of the outer ring 31 is equal to the speed of the rotating disk 25A of the secondary encoder 25. Moreover, the speed V2 of the outer ring 31 = D1 / D2×V1 = 0.615×V1.

[0030] When the additional speed reducer 30 is not provided, when the movable range of the machine 3 is ±540° (±1.5 turns), the rotary disk 25A of the secondary encoder 25 also rotates ±540° (1 turn or more and 2 turns or less). In this case, the secondary encoder 25 cannot be used any more.

[0031] However, in an embodiment in which the additional speed reducer 30 is provided, the movable range of the machine 3 of ±540° is converted to ±332° (=540×0.615), and therefore, the rotating disk 25A of the secondary encoder 25 rotates ±332°. In other words, by providing the additional speed reducer 30, the rotating disk 25A of the secondary encoder 25 rotates within one revolution (within ±360°).

[0032] In other words, the outer diameter D1 of the sun gear 19 and the inner diameter of the outer ring 31 may be set so as to satisfy the following conditions (1) and (2).

[0033] Condition (1): ±360°×D1 / D2 is a value greater than ±0, and

[0034] Condition (2): ±720°×D1 / D2 is less than ±360°.

[0035] As long as these conditions are met, even when the shaft portion 23 performs a rotational motion of more than one turn and less than two turns, no additional battery is required, and the secondary encoder 25 can continue to be used throughout the entire movable range of the output shaft 23. That is, in the embodiment of the present disclosure, it is possible to provide a position detection system 5 that can continue to be used throughout the entire movable range of the output shaft 23 without a battery even when the shaft portion 23 performs a rotational motion of more than ±360° and less than ±720° (more than one turn and less than two turns). In addition, of course, the primary encoder 15 can also continue to be used throughout the entire movable range of the output shaft 23.

[0036] Furthermore, the position detection system 5 is preferably assembled to the joint axis of the robot 3. The joint axis of the robot 3 generally performs a rotational motion of more than ±360° and less than ±720° (more than one turn and less than two turns). Therefore, even in such a case, the position detection system 5 can continue to be used without a battery within the above-mentioned rotational motion range of the joint axis, which is particularly advantageous.

[0037] Figure 3 The second embodiment of the present invention is a schematic side view of the position detection system. The additional speed reducer 30' in the second embodiment is a combination of two spur gears and a secondary gear. Figure 3 As shown, the additional speed reducer 30' includes a spur gear 39 fixed to the rear end of the motor shaft 13, a secondary gear 35 including a large diameter gear 31 and a small diameter gear 32, and a spur gear 29. Figure 3 It can be seen that the spur gear 39 is engaged with the large-diameter gear 31 of the secondary gear 35 , and the small-diameter gear 32 of the secondary gear 35 is engaged with the spur gear 39 .

[0038] And, in Figure 3 In the embodiment, the secondary encoder 25 is arranged on the end surface of the large diameter gear 31. Therefore, Figure 3The secondary encoder 25 shown detects the speed of the output shaft 23 which has been reduced in speed by a first reduction ratio.

[0039] and, Figure 4 Yes means Figure 3 FIG. 1 is a diagram of a modified example of . Figure 4 In the embodiment, an additional speed reducer 30' is provided which is the same as the above. Moreover, the secondary encoder 25 is provided on the end surface of the spur gear 29. Therefore, Figure 4 The secondary encoder 25 shown detects the speed of the output shaft 23 reduced in speed by the first reduction ratio and the second reduction ratio.

[0040] In the second embodiment, the speed of the output shaft 23 is reduced by only the first reduction ratio between the spur gear 39 and the large diameter gear 31 of the secondary gear 35, and the speed of the output shaft 23 is reduced by only the second reduction ratio between the small diameter gear 32 of the secondary gear 35 and the spur gear 39. As in the above, the reduction ratio (the product obtained by multiplying the first reduction ratio by the second reduction ratio) of the additional speed reducer 30' is set within one rotation of the rotary disk 25A for the secondary encoder 25 in the entire area of ​​the movable range of the machine 3 having the motor 10 and the speed reducer 20. As can be seen from this, the same effect as in the above can be obtained.

[0041] The method disclosed

[0042] According to a first method, a position detection system is provided, comprising: a primary encoder, which detects the position of a motor shaft of a motor; a secondary encoder, which detects the position of an output shaft of a reducer combined with the motor; and an additional reducer, which is arranged between the output shaft of the reducer and the secondary encoder, and the reduction ratio of the additional reducer is set so that a rotating disk for the secondary encoder rotates within one revolution in the entire area of ​​the movable range of the machine having the motor and the reducer.

[0043] According to a second aspect, in the first aspect, the additional speed reducer is a planetary gear device, a wave gear speed reducer, a cycloid speed reducer, or a combination of a spur gear and a two-stage gear.

[0044] According to a third aspect, in the first or second aspect, the position detection system is mounted on the robot.

[0045] According to a fourth aspect, an actuator is provided, comprising: a motor; a reducer coupled to the motor; a primary encoder for detecting the position of a motor shaft of the motor; a secondary encoder for detecting the position of an output shaft of the reducer; and an additional reducer disposed between the output shaft of the reducer and the secondary encoder, wherein the reduction ratio of the additional reducer is set so that a rotating disk for the secondary encoder rotates within one revolution of the entire movable range of the machine having the motor and the reducer.

[0046] According to a fifth aspect, in the fourth aspect, the additional speed reducer is a planetary gear device, a wave gear speed reducer, a cycloid speed reducer, or a combination of a spur gear and a two-stage gear.

[0047] According to a sixth aspect, in the fifth or sixth aspect, the actuator is mounted on the robot.

[0048] The embodiments of the present disclosure have been described in detail, but the present disclosure is not limited to the above-mentioned embodiments. These embodiments can be variously added, replaced, changed, partially deleted, etc. without departing from the scope of the main purpose of the invention, or without departing from the idea and main purpose of the present disclosure derived from the contents recorded in the claims and their equivalents. For example, in the above-mentioned embodiments, the order of each action and the order of each process are shown as an example, but are not limited to this. In addition, the same applies to the case where numerical values ​​or mathematical formulas are used in the description of the above-mentioned embodiments. Furthermore, several appropriate combinations of the aforementioned embodiments are included in the scope of the present disclosure.

[0049] Explanation of symbols

[0050] 1, 2: Connecting rod

[0051] 3: Machinery (Robot)

[0052] 5: Position detection system

[0053] 6: Actuator

[0054] 7: Memory

[0055] 8: Battery

[0056] 9: Controller

[0057] 10: Motor

[0058] 11: Stator

[0059] 12: Rotor

[0060] 13: Motor shaft

[0061] 15: Primary Encoder

[0062] 16: Inspection Department

[0063] 20: Reducer

[0064] 23: Output shaft

[0065] 25: Secondary encoder

[0066] 26: Inspection Department

[0067] 30, 30': Add reducer

[0068] 50: Built-in brake

Claims

1. A position detection system, characterized in that: have: a primary encoder that detects the position of a motor shaft of the motor; a secondary encoder that detects a position of an output shaft of a speed reducer coupled to the motor; and An additional speed reducer is arranged between the output shaft of the speed reducer and the secondary encoder, The reduction ratio of the additional reduction gear is set so that the rotation disk for the secondary encoder can rotate within one revolution in the entire movable range of the machine including the motor and the reduction gear.

2. The position detection system according to claim 1, characterized in that: The additional speed reducer is a planetary gear device, a wave gear speed reducer, a cycloid speed reducer, or a combination of a spur gear and a secondary gear.

3. The position detection system according to claim 1 or 2, characterized in that: Mounted on a robot.

4. An actuator, characterized in that: have: motor; a speed reducer combined with the motor; a primary encoder that detects the position of a motor shaft of the motor; a secondary encoder for detecting the position of the output shaft of the reducer; as well as An additional speed reducer is arranged between the output shaft of the speed reducer and the secondary encoder, The reduction ratio of the additional reduction gear is set so that the rotation disk for the secondary encoder can rotate within one revolution in the entire movable range of the machine including the motor and the reduction gear.

5. The actuator according to claim 1, characterized in that: The additional speed reducer is a planetary gear device, a wave gear speed reducer, a cycloid speed reducer, or a combination of a spur gear and a secondary gear.

6. The actuator according to claim 1 or 2, characterized in that: Mounted on a robot.

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