Position detection system, actuator, and position detection method

Abstract

A position detection system (1) includes a main encoder (15) that detects a position of a motor shaft of a motor (10), and a sub-encoder (25) that detects a position of an output shaft of a speed reducer (20). The position detection system (1) is further provided with encoder power supplies (8, 9) for energizing and operating at least one of the main encoder and the sub-encoder under a predetermined condition.

Description

Technical Field

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

[0002] The actuator includes a servo motor and a reducer connected to each other. A main 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 sub-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, such as 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 circle, the total number of rotations of the main encoder can be obtained based on the absolute position information of the sub-encoder. In this case, each encoder can be used continuously 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 actuator is sometimes assembled in a specific machine, such as a robot, that has a shaft that can rotate within ±360° or more and ±720° or less (1 or more and 2 or less turns). When the shaft rotates 1 or more and 2 or less 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, comprising: a motor mounted on a machine; a reducer combined with the motor; a main encoder detecting the position of a motor shaft of the motor; and a sub-encoder detecting the position of an output shaft of the reducer, wherein the position detection system comprises an encoder power supply, and the encoder power supply energizes at least one of the main encoder and the sub-encoder to activate the encoder under predetermined conditions.

[0012] According to another embodiment of the present disclosure, an actuator is provided, which comprises: a motor; a reducer combined with the motor; a main encoder that detects the position of a motor shaft of the motor; and a sub-encoder that detects the position of an output shaft of the reducer, the actuator comprising an encoder power supply that energizes at least one of the main encoder and the sub-encoder under predetermined conditions to activate the encoder.

[0013] According to another embodiment of the present disclosure, there is provided a position detection method of a position detection system, wherein the position detection system comprises: a main encoder, which detects the position of a motor shaft of a motor; and a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor, wherein the power supply to the motor is stopped according to a stop command of the machine, whereby the rotor of the motor moves due to inertia, and at least one of the main encoder and the sub-encoder is energized by an encoder power supply to activate it, and the position of at least one of the main encoder and the sub-encoder when the output shaft is stopped is stored.

[0014] 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

[0015] Figure 1 This is a schematic side view of a position detection system according to the first and second embodiments of the present disclosure.

[0016] Figure 2 This is a flowchart showing the operation of the position detection system according to the first embodiment.

[0017] Figure 3 This is a flowchart showing the operation of the position detection system according to the second embodiment.

[0018] Figure 4 This is a diagram showing the relationship between time and the position of the output shaft of the speed reducer. DETAILED DESCRIPTION

[0019] 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 numerals.

[0020] 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 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.

[0021] exist Figure 1In the embodiment, the actuator 6 arranged on the connecting rod 1 includes a motor 10, such as a servo motor, which are connected to each other, 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 predetermined range of motion to perform positioning control. In addition, the reduction ratio of the reducer 20 is, for example, 1:50.

[0022] The motor shaft 13 is, for example, a hollow shaft, and a primary encoder 15 is mounted on 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.

[0023] The output shaft 23 extends toward the motor 10 through the hollow motor shaft 13, and a secondary encoder 25 is installed at the rear end of the output shaft 23. 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 main encoder 15 and the secondary encoder 25 are respectively provided with a rotating disk 15A, 25A.

[0024] 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 The position detection system 5 shown in the figure includes a memory 7 and a battery 8 shared by the main encoder 15 and the sub encoder 25. However, the main encoder 15 and the sub encoder 25 may each have a separate memory and battery.

[0025] 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 to position 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 main encoder 15 and the sub-encoder 25 when the machine 3 having the connecting rods 1 and 2 is in motion.

[0026] Figure 2This is a flowchart showing the operation of the position detection system according to the first embodiment. Figure 2 The content shown is implemented when a machine 3, such as a robot 3, which is operating according to an operation instruction, stops due to a specific reason and the operation of the machine 3 needs to be restarted. Figure 2 The program related to the operations shown is stored in a storage unit (not shown) connected to the controller 9. In the following, the case where the machine 3 is a robot 3 is described, but the present invention is also applicable even if the machine 3 is a machine tool or the like.

[0027] First, in step S11, the robot 3 stops due to a specific reason, such as interference between the robot 3 and a foreign object. As a result, the built-in brake 50 is automatically activated for safety purposes, stopping the motor shaft 13. In addition, the controller 9 stops energizing the motor 10, the main encoder 15, and the sub-encoder 25. As a result, the joints of the robot 3 do not move.

[0028] Next, in step S12, the operator releases the built-in brake 50 to enable the motor shaft 13 to rotate. Then, the operator manually starts the robot 3 to move (step S13). At the same time, the encoder power supply, such as the controller 9, starts supplying power to at least one of the main encoder 15 and the sub-encoder 25 (step S14).

[0029] In other words, in the first embodiment, in a predetermined condition, that is, when the robot 3 stops and the brake mechanism 50 is released, the encoder power supply, for example, the controller 9, starts supplying power to at least one of the main encoder 15 and the sub-encoder 25. As a result, the energized encoders 15 and 25 continue to detect the absolute positions PA1 and PA2 and the total rotation numbers PB1 and PB2 (step S15).

[0030] Next, in step S16, for example, when the robot 3 is sufficiently separated from the foreign matter and the above-mentioned specific cause is eliminated, the operator stops the robot 3 manually. When the robot 3 stops, the absolute positions PA1, PA2 and the total rotation times PB1, PB2 are stored in the memory 7, and the encoder power supply, for example, the controller 9, stops supplying power to at least one of the main encoder 15 and the sub-encoder 25 (step S17). And, in step S18, the built-in brake 50 is activated again to prevent the motor shaft 13 from rotating. As a result, the robot 3 is in the same state as when the robot 3 stopped in step S1.

[0031] Next, in step S19, it is determined whether there is an action command for the robot 3. Then, if there is no action command, wait until there is an action command. Then, if there is an action command, it proceeds to step S20 and releases the built-in brake 50 again. As a result, the motor shaft 13 becomes rotatable. Then, in step S21, the controller 9 reads the absolute positions PA1, PA2, and the total number of rotations PB1, PB2 stored in the memory 7. Thereafter, according to the action command received in step S19, the action of the robot 3 is restarted (step S22).

[0032] Thus, in the first embodiment, after step S12, when the robot 3 stops, the brake mechanism 50 is released. In this case, the controller 9, which is the encoder power supply, continues the position detection of at least one of the main encoder 15 and the sub-encoder 25, and stores the result in the memory 7 (steps S15 and S17). Then, after the content of the memory 7 is read, the operation of the machine 3 is resumed (steps 21 and 22).

[0033] Therefore, in the first embodiment, 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 sub-encoder 25 can be continuously used within the entire movable range of the output shaft 23. That is, in the first embodiment of the present disclosure, it is possible to provide a position detection system 1 that is battery-free and can be continuously used within the entire movable range of the output shaft 23. In addition, of course, the main encoder 15 can also be continuously used within the entire movable range of the output shaft 23.

[0034] and, Figure 3 This is a flowchart showing the operation of the position detection system according to the second embodiment. Figure 3 The content shown is applicable to the case where a machine 3, such as a robot 3, stops urgently during operation. Figure 3 The program related to the operations shown is stored in a storage unit (not shown) connected to the controller 9. In the following, the case where the machine 3 is a robot 3 is described, but the machine 3 can also be applied to a machine tool or the like.

[0035] First, in step S31, the robot 3 operates according to the operation program. In step S32, it is determined whether an emergency stop command for the robot 3 is issued. Unless a stop command is issued, the robot 3 continues to operate. Then, if a stop signal is issued, the process proceeds to step S33.

[0036] When the stop signal is issued, the power supply from the controller 9 to the robot 3 is stopped (step S33). That is, the controller 9 stops the power supply to the motor 10, the main encoder 15, and the sub-encoder 25. As a result, the joints of the robot 3 do not move. At this time, although the motor 10 stops, the output shaft 23 of the speed reducer 20 continues to move due to inertia (step S34).

[0037] Here, Figure 4 is a graph showing the relationship between time and the position of the output shaft of the reducer. Figure 4 In FIG. 1 , the horizontal axis represents time, and the vertical axis represents the position of the output shaft 23 of the reducer 20. Figure 4 As shown, even if the robot 3 stops according to the stop signal, the output shaft 23 moves due to inertia, so the position of the output shaft 23 continues to change.

[0038] Therefore, in step S35 , the battery 8 (reserve power source) serving as the encoder power source supplies power not only to the memory 7 but also to at least one of the main encoder 15 and the sub-encoder 25 .

[0039] In other words, in the second embodiment, in a predetermined situation, that is, in a situation where the output shaft moves due to inertia due to the stop of power supply to the motor 10, the encoder power supply, for example, the battery 8, starts to supply power to at least one of the main encoder 15 and the sub-encoder 25. As a result, the energized encoders 15 and 25 continue to detect the absolute positions PA1 and PA2 and the total rotation numbers PB1 and PB2 (step S35).

[0040] Refer again Figure 4 It is known that the output shaft 23 moving due to inertia stops after a certain period of time. If the stop of the output shaft 23 can be confirmed in step S36, the process moves to step S37 and the absolute positions PA1, PA2 and the total rotation numbers PB1, PB2 are stored in the memory 7 (step S37).

[0041] Then, in step S38, it is determined whether the stop command of the robot 3 is released. If it is released, the process proceeds to step S39. In step S39, the power supply from the controller 9 to the robot 3 is started. That is, in step S40, the controller 9 reads the absolute positions PA1, PA2, and the total number of rotations PB1, PB2 stored in the memory 7. Then, according to the motion command of the motion program of the robot 3, the motion of the robot 3 is restarted (step S41).

[0042] Thus, in the second embodiment, after step S33, the power supply to the motor 10 is stopped, causing the output shaft to move due to inertia. Then, the position detection of at least one of the main encoder 15 and the sub-encoder 25 is continued by the battery 8 as the encoder power supply, and the result is stored in the memory 7 (steps S35, S37). Then, after the content of the memory 7 is read, the operation of the machine 3 is resumed (steps 40, 41).

[0043] Therefore, in the second embodiment, 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 sub-encoder 25 can be continuously used in the entire movable range of the output shaft 23. That is, in the second embodiment of the present disclosure, it is possible to provide a position detection system 1 that is battery-free and can be continuously used in the entire movable range of the output shaft 23. In addition, as for the main encoder 15, it is of course possible to continuously use it in the entire movable range of the output shaft 23.

[0044] In the first and second embodiments, the encoder power supply is the controller 9 or the battery 8 of the position detection system 1, so no additional power supply is required. In addition, the encoder power supply (controller 9, battery 8) supplies power to at least one of the main encoder 15 and the sub-encoder 25 under the above-mentioned predetermined conditions. However, the encoder power supply (controller 9, battery 8) can also supply power only to the sub-encoder 25 under the above-mentioned predetermined conditions. In such a case, the total number of rotations PB1 of the main encoder 15 can be obtained based on the absolute position PA2 of the sub-encoder 25 and the total number of rotations PB2, and the absolute position PA1 can be calculated. Therefore, it can be seen that the power required by the encoder power supply is less. Such a situation is also included in the scope of the present disclosure.

[0045] The method disclosed

[0046] According to a first method, a position detection system is provided, which comprises: a main encoder, which detects the position of a motor shaft of a motor; and a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor, the position detection system comprises an encoder power supply, and the encoder power supply energizes at least one of the main encoder and the sub-encoder under predetermined conditions to activate it.

[0047] According to a second aspect, in the first aspect, the predetermined condition is a condition in which a brake mechanism that stops at least one of a motor shaft of the motor and the output shaft of the speed reducer is released when the machine is stopped.

[0048] According to a third aspect, in the second aspect, the encoder power supply is a controller that controls the machine.

[0049] According to a fourth aspect, in the first aspect, the predetermined condition is a condition in which the output shaft moves due to inertia after the supply of electric power to the motor is stopped.

[0050] According to a fifth aspect, in the fourth aspect, the encoder power supply is a capacitor or a backup battery.

[0051] According to a sixth aspect, in the first aspect, the encoder power supply supplies power only to the sub-encoder.

[0052] According to the seventh method, an actuator is provided, comprising: a motor; a reducer combined with the motor; a main encoder that detects the position of the motor shaft of the motor; and a sub-encoder that detects the position of the output shaft of the reducer, wherein the actuator comprises an encoder power supply that energizes at least one of the main encoder and the sub-encoder under predetermined conditions to activate the encoder.

[0053] According to an eighth aspect, in the seventh aspect, the predetermined condition is a condition in which a brake mechanism that stops at least one of a motor shaft of the motor and the output shaft of the speed reducer is released when the machine is stopped.

[0054] According to a ninth aspect, in the eighth aspect, the encoder power supply is a controller that controls the machine.

[0055] According to a tenth aspect, in the seventh aspect, the predetermined condition is a condition in which the output shaft moves due to inertia after the supply of electric power to the motor is stopped.

[0056] According to an eleventh aspect, in the tenth aspect, the encoder power supply is a capacitor or a backup battery.

[0057] According to a twelfth aspect, in the seventh aspect, the encoder power supply supplies power only to the sub-encoder.

[0058] According to the thirteenth embodiment, a position detection method of a position detection system is provided, the position detection system comprising: a main encoder, which detects the position of a motor shaft of a motor; and a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor. In the position detection method, according to a stop command of the machine, the power supply to the motor is stopped, whereby the rotor of the motor moves due to inertia, and at least one of the main encoder and the sub-encoder is energized by an encoder power supply to activate it, and the position of at least one of the main encoder and the sub-encoder when the output shaft is stopped is stored.

[0059] According to a fourteenth aspect, in the thirteenth aspect, the encoder power supply is a capacitor or a backup battery.

[0060] 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 scope of the patent protection requested and its equivalents. For example, in the above-mentioned embodiments, the order of each action and the order of each processing are shown as an example, but are not limited to this. In addition, the same is true for the case where numerical values ​​or mathematical formulas are used in the description of the above-mentioned embodiments. Furthermore, appropriate combinations of several of the aforementioned embodiments are included in the scope of the present disclosure.

[0061] As mentioned above, although embodiment of this disclosure is described, it is obvious to a person skilled in the art that various corrections and changes can be made without departing from the scope of the disclosure of the claims described later.

[0062] Explanation of symbols

[0063] 1. Position detection system,

[0064] 3. Machinery (Robots),

[0065] 5. Position detection system,

[0066] 6 actuators,

[0067] 7Memory,

[0068] 8 batteries (encoder power supply),

[0069] 9 controller (encoder power supply),

[0070] 10 motors,

[0071] 11 stator,

[0072] 12 rotors,

[0073] 13 motor shaft,

[0074] 15 main encoder,

[0075] 16. Inspection Department,

[0076] 20 reducer,

[0077] 23 output shaft,

[0078] 25 pairs of encoders,

[0079] 26 Detection Department,

[0080] 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; and a secondary encoder that detects the position of an output shaft of a speed reducer combined with the motor, The position detection system includes an encoder power supply configured to energize and operate at least one of the main encoder and the sub-encoder under a predetermined condition.

2. The position detection system according to claim 1, characterized in that: The predetermined condition is a condition in which the machine is stopped and a brake mechanism that stops at least one of the motor shaft of the motor and the output shaft of the speed reducer is released.

3. The position detection system according to claim 2, characterized in that: The encoder power supply is a controller that controls the machine.

4. The position detection system according to claim 1, characterized in that: The predetermined condition is a condition in which the output shaft moves due to inertia after the supply of electric power to the motor is stopped.

5. The position detection system according to claim 4, characterized in that: The encoder power supply is a capacitor or a backup battery.

6. The position detection system according to claim 1, characterized in that: The encoder power supply only energizes the slave encoder.

7. 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; and A secondary encoder, which detects the position of the output shaft of the reducer, The actuator includes an encoder power supply configured to energize at least one of the main encoder and the sub-encoder to operate the main encoder in a predetermined state.

8. The actuator according to claim 7, characterized in that The predetermined condition is a condition in which the machine is stopped and a brake mechanism that stops at least one of the motor shaft of the motor and the output shaft of the speed reducer is released.

9. The actuator according to claim 8, characterized in that The encoder power supply is a controller that controls the machine.

10. The actuator according to claim 7, characterized in that The predetermined condition is a condition in which the output shaft moves due to inertia after the supply of electric power to the motor is stopped.

11. The actuator according to claim 10, characterized in that The encoder power supply is a capacitor or a backup battery.

12. The actuator according to claim 7, characterized in that The encoder power supply only energizes the slave encoder.

13. A position detection method of a position detection system, the position detection system comprising: a main encoder for detecting the position of a motor shaft of a motor; and a sub-encoder for detecting the position of an output shaft of a reducer coupled to the motor, characterized in that: The power supply to the motor is stopped according to the stop command of the machine, whereby the rotor of the motor moves due to inertia. At least one of the main encoder and the sub-encoder is powered by an encoder power supply to operate. The position of at least one of the main encoder and the sub-encoder when the output shaft is stopped is stored.

14. The position detection method according to claim 13, characterized in that: The encoder power supply is a capacitor or a backup battery.

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