Position detection system, actuator, and position detection method

Abstract

The position detection system (5) includes a main encoder (15) that detects the position of the motor shaft, a sub-encoder (25) that detects the position of the output shaft of the decelerator, and a calculation unit (9). The reduction ratio of the speed reducer is 1 / n, and n is a non-integer. The calculation unit calculates a plurality of position calculation values relating to a position within one rotation of the motor shaft on the basis of a position within one rotation of the sub-encoder, and calculates the total number of turns of rotation of the sub-encoder on the basis of an actual position value relating to a position within one rotation of the rotor and the plurality of position calculation values.

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] Moreover, the following method is proposed in Japanese Patent Gazette No. 2006-300596: the reduction ratio of the reducer is set to 1 / n (n is a non-integer), the value of the "determination criterion" is calculated according to the position of the sub-encoder, and the ±1 rotation of the sub-encoder is determined based on the value of the determination criterion and the positive and negative determination result of the position of the main encoder.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2007-113932

[0007] Patent Document 2: Japanese Patent Application Publication No. 2006-300596 Summary of the invention

[0008] Problems to be solved by the invention

[0009] However, the method of Japanese Patent Application Laid-Open No. 2006-300596 cannot be used as a battery-less absolute encoder when the output shaft rotates more than two times.

[0010] Therefore, a position detection system that can be used without requiring an additional battery even when the output shaft rotates two or more times is desired.

[0011] Means for solving problems

[0012] According to a first embodiment of the present disclosure, a position detection system is provided, which comprises: a main encoder, which detects the position of a motor shaft of a motor; a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor; and a calculation unit, wherein the reduction ratio of the reducer is 1 / n, and n is a non-integer, and the calculation unit calculates a plurality of position calculation values ​​of the main encoder related to the absolute position of the rotor within one rotation based on the absolute position of the sub-encoder within one rotation, and the calculation unit calculates the total number of rotations of the sub-encoder based on the actual position value related to the absolute position of the rotor within one rotation detected by the main encoder and the plurality of position calculation values.

[0013] According to another embodiment of the present disclosure, a position detection system is provided, which comprises: a main encoder, which detects the position of a motor shaft of a motor; a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor; and a calculation and determination unit, which calculates a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft within one rotation detected by the sub-encoder, and the calculation and determination unit also determines that there is an abnormality in the position of at least one of the main encoder and the sub-encoder when the absolute value of the deviation between the position actual value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the position calculation value is greater than a predetermined value.

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

[0016] Figure 2 Yes means Figure 1 A first flow chart of the operation of the position detection system is shown.

[0017] Figure 3 It is a diagram showing the relationship between the position of the output shaft and the position of the input shaft.

[0018] Figure 4 This is another diagram showing the relationship between the position of the output shaft and the position of the input shaft.

[0019] Figure 5 This is a second flowchart showing the operation of the position detection system according to the second embodiment. DETAILED DESCRIPTION

[0020] 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.

[0021] 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 in a machine 3 having an axis, for example, a robot 3. Hereinafter, a case where the position detection system 5 is assembled in the robot 3 will be described, but the same is true for a case where the position detection system 5 is assembled in another machine 3 having an axis, for example, a machine tool.

[0022] exist Figure 1 In 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 predetermined range of motion to perform positioning control. The reduction ratio n of the reducer 20 is set to a positive non-integer, for example, n=α+1 / β (α, β are positive numbers greater than 1).

[0023] The motor shaft 13 is, for example, a hollow shaft, and a main encoder 15 having a rotating disk 15A is mounted on its rear end. The main 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 θp and the total number of rotations 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.

[0024] The output shaft 23 extends toward the motor 10 through the hollow motor shaft 13, and a sub-encoder 25 having a rotating disk 25A is mounted on the rear end of the output shaft 23. The sub-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 θs and the total number of rotations i of the output shaft 23 within one rotation are detected by a known method. The detected information is stored in the memory 7, for example, a volatile memory.

[0025] 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 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 a separate battery.

[0026] The information stored in the memory 7 is supplied to the controller 9. The controller 9 may also be a control device for controlling the machine 3, or an LSI mounted on the encoders 15 and 25. The controller 9 drives and controls the motor 10 based on the supplied information, 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 is in motion.

[0027] In addition, the controller 9 plays the role of a calculation unit, which calculates multiple position calculation values ​​related to the absolute position of the main encoder 15 within one rotation of the motor shaft 13 based on the absolute position of the sub-encoder 25 within one rotation, and calculates the total number of rotations of the sub-encoder 25 based on the actual position value and multiple position calculation values ​​related to the absolute position of the motor shaft 13 within one rotation detected by the main encoder 15.

[0028] In addition, the controller 9 plays the role of a calculation and determination unit, which calculates a position calculation value related to the absolute position of the motor shaft 13 within one rotation based on the absolute position of the output shaft 23 within one rotation detected by the sub-encoder 25, and determines that there is an abnormality in the position of at least one of the main encoder 15 and the sub-encoder 25 when the absolute value of the deviation between the position actual value related to the absolute position of the motor shaft 13 within one rotation detected by the main encoder 15 and the position calculation value is greater than a predetermined value.

[0029] Figure 2 Yes means Figure 1 The first flow chart of the operation of the position detection system shown in FIG. Figure 2 The contents of the program shown are stored in a storage unit (not shown) in the controller 9 or in the memory 7. The program is executed appropriately when the motor 10 is driven. Figure 2 The content shown.

[0030] First, in step S11, the sub-encoder 25 detects the absolute position θs of the output shaft 23 within one rotation. Next, in step S12, the controller 9 uses the detected absolute position θs to calculate the position calculation value θp*(i) (i is a positive number less than β) of the main encoder 15 related to the absolute position within one rotation based on the following formula (1).

[0031] θp*(i)=MOD[{(θs×(α+1 / β)+(360 / β)×(i-1))}÷360]×360

[0032] Formula (1)

[0033] In addition, "MOD[]" is a function that calculates the remainder of division.

[0034] Here, Figure 3 Indicates the relationship between the position of the output shaft and the position of the input shaft. Figure 3 In the figure, the horizontal axis represents the position of the output shaft 23 of the reducer 20, and the vertical axis represents the position of the input shaft. The "position of the input shaft" refers to the position of the input shaft that inputs the sub-encoder 25. In this application specification, since the sub-encoder 25 is connected to the downstream of the main encoder 15, the "position of the input shaft" can also be said to be the position of the rotating disk 15A of the main encoder 15 or the position of the motor shaft 13. In addition, Figure 3 In the figure, both the horizontal and vertical axes are expressed in degrees. In addition, as described above, the reduction ratio n of the reducer 20 is n=α+1 / β (α, β are positive numbers greater than 1). Figure 3 In the example shown, α=2 and β=3.

[0035] exist Figure 3 , three lines L1, L2, and L3 are shown. The number of these lines L1, L2, and L3 is equal to the value of β described above. The solid line L1 represents the position of the input shaft when the output shaft 23 rotates the first circle. The dotted line L2 represents the position of the input shaft when the output shaft 23 rotates the second circle. The single-point chain line L3 represents the position of the input shaft when the output shaft 23 rotates the third circle.

[0036] according to Figure 3 It can be seen that the position detection system 5 in the first embodiment can detect the β-th circle point of the output shaft 23. In addition, the position of the output shaft 23 is different in its first rotation and second rotation. In the first embodiment, the total number of rotations of the output shaft 23 is obtained by using the difference between the position of the first rotation and the position of the second rotation.

[0037] exist Figure 3 In the example shown, β = 3, so in Figure 3 The vertical axis of θp*(1), θp*(2), and θp*(3) are values ​​of the vertical axis corresponding to intersections between the absolute position θs of the output shaft 23 and the three lines L1, L2, and L3.

[0038] In step S13, the controller 9 obtains the position detection value θp detected by the main encoder 15 and related to the absolute position of the motor shaft 13 within one rotation. In addition, the controller 9 calculates the absolute values ​​θd(i) (=|θp-θp*(i)|) of the multiple deviations between the position detection value θp and the multiple position calculation values ​​θp*(i). Figure 3In FIG. 1 , arrows are used to indicate the absolute values ​​of the deviations θd(1) (=|θp-θp*(1)|), θd(2) (=|θp-θp*(2)|), and θd(3) (=|θp-θp*(3)|).

[0039] Next, in step S14, the controller 9 selects from a plurality of absolute values, namely Figure 3 Select the minimum value Minθd(i) from θd(1), θd(2), and θd(3). Figure 3 In the example shown, since θd(2)<θd(1)<θd(3), θd(2) corresponds to the minimum value Minθd(i).

[0040] Then, in step S15, the controller 9 compares the selected minimum value Minθd(i) with the first error determination value θj1. The first error determination value θj1 is calculated in advance based on the following equation (2).

[0041] θj1=360 / β-n·θsa_max-θpa_max-θnoiS_max

[0042] Formula (2)

[0043] Here, θsa represents the detection accuracy determined by the characteristics of the sub-encoder 25, and θsa_max is the value when the detection accuracy is the lowest. θpa represents the detection accuracy determined by the characteristics of the main encoder 15, and θpa_max is the value when the detection accuracy is the lowest. Moreover, θnois represents the amplitude of the disturbance of the position detection system 5, and θnois_max is its maximum value.

[0044] When it is determined in step S15 that the minimum value Minθd(i) is not greater than the first error determination value θj1, it is determined that there is no problem and the process proceeds to step S19. Then, in step S19, the minimum value Minθd(i) is compared with the second error determination value θj2. The second error determination value θj2 is calculated in advance based on the following formula (3).

[0045] θj2≥θj1-360=n·θsa_max+θpa_max+θnois_max

[0046] Formula (3)

[0047] According to formula (3), the second error determination value θj2 is smaller than the first error determination value θj1.

[0048] Then, when it is determined that the minimum value Minθd(i) is not less than the second error determination value θj2, the process proceeds to step S21. In step S21, it is determined that there is an abnormality in the position of at least one of the main encoder 15 and the sub-encoder 25. Then, as a detection error, the controller 9 stops the operation of the motor 10. In addition, at this time, the meaning may also be displayed on a display unit (not shown), such as a screen of a teaching control panel.

[0049] On the other hand, when it is determined in step S19 that the minimum value Minθd(i) is less than the second error determination value θj2, the process proceeds to step S20. In step S20, the controller 9 calculates the total number of rotations of the sub-encoder 25 based on the minimum value Minθd(i). Figure 3 In the example shown, θd(2) is the minimum value Minθd(i), so it can be seen that the total number of rotations i is 2.

[0050] In this way, the process of obtaining the total number of rotations of the sub-encoder 25 in the first embodiment of the present disclosure does not require an additional battery. Therefore, in the first embodiment of the present disclosure, even when the output shaft 23 rotates more than two times, the position detection system 5 can be used without an additional battery. In other words, even if the encoders 15 and 25 are operated without the controller 9 supplying power to the encoders 15 and 25, the position detection system 5 in the first embodiment can obtain the total number of rotations of the output shaft 23.

[0051] In addition, when it is determined in step S15 that the minimum value Minθd(i) is larger than the first error determination value θj1, the process proceeds to step S16. Figure 4 is with Figure 3 Another diagram similarly shows the relationship between the position of the output shaft and the position of the input shaft. The case where the minimum value Minθd(i) is determined to be greater than the first error determination value θj1 as in step S15 means that, for example Figure 4 The situation is as shown in the example.

[0052] exist Figure 4 In the example, the absolute position θs of the output shaft 23 during one rotation is in the same Figure 3 Different locations. Figure 4 When the absolute values ​​of the deviations θd(1) (=|θp-θp*(1)|), θd(2) (=|θp-θp*(2)|), and θd(3) (=|θp-θp*(3)|) in the example shown are compared, θd(3)<θd(2)<θd(1).

[0053] exist Figure 4In the example, the minimum value Minθd(i) should be θd(1), and setting θd(3) as the minimum value Minθd(i) is obviously wrong. However, since the position of the motor shaft 13 relative to the main encoder 15 is near 0° (near 360°), it is difficult to make the above determination. Therefore, assuming that the position of the motor shaft 13 relative to the main encoder 15 is near 0°, in step S16, the controller 9 performs position jump correction on the absolute value of the deviation θd(i) obtained in step S13.

[0054] Equation (4) for position jump correction is as follows.

[0055] θd(i)=|θp-θp*(i)|=360-360(i-1) / β-nθsa-θpa-θnois

[0056] Formula (4)

[0057] Thus, θd(1), θd(2), and θd(3) are corrected as shown in the following equations (5) to (7).

[0058] θd(1)=|θp-θp*(1)|=360-nθsa-θpa-θnois

[0059] Formula (5)

[0060] θd(2)=|θp-θp*(2)|=240-nθsa-θpa-θnois

[0061] Formula (6)

[0062] θd(3)=|θp-θp*(3)|=120-nθsa-θpa-θnois

[0063] Formula (7)

[0064] In equations (4) to (7), θsa and θpa are approximately 0.01 degrees, and θnois is approximately several degrees.

[0065] Then, in step S17, the controller 9 selects the minimum value Minθd(i) from the plurality of absolute values ​​θd(i) corrected in this way. Figure 4 In the example shown, the minimum value Minθd(i) is the corrected absolute value θd(1). By such position jump correction, the correct minimum value Minθd(i) is selected (in Figure 4 where is the corrected absolute value θd(1)).

[0066] Then, in step S18, the correct minimum value Minθd(i) after correction is reset as the minimum value Minθd(i). Then, the process proceeds to step S20, and the total number of rotations of the sub-encoder 25 is calculated in the same manner as above according to the new minimum value Minθd(i). Figure 4 In the example shown, θd(1) is the minimum value Minθd(i), so it can be seen that the total number of rotations i is 1.

[0067] Due to such a configuration, even when the position of the motor shaft 13 relative to the main encoder 15 is near 0°, the total number of rotations of the sub encoder 25 can be accurately obtained.

[0068] in addition, Figure 5 is a second flowchart showing the operation of the position detection system according to the second embodiment. Figure 5 The contents of the program shown are stored in a storage unit (not shown) in the controller 9 or in the memory 7. When the motor 10 is driven, the program is executed as appropriate. Figure 5 The content shown.

[0069] The reduction ratio n of the reducer 20 of the second embodiment is not limited to the above-mentioned reduction ratio. That is, the reduction ratio n in this case may also be 1 / α (α is a positive number greater than 1). In addition, an additional reducer (not shown) is arranged between the output shaft 23 and the auxiliary encoder 25, and the case where the overall reduction ratio of the reducer 20 and the additional reducer is 1 / α' is also included in the second embodiment (α' is a positive number greater than 1).

[0070] First, in step S31, similarly to the above, the sub-encoder 25 detects the position detection value θs related to the absolute position of the output shaft 23 within one rotation. Then, in step S32, the position detection value θs is compared with the reference value θs. Figure 3 Similarly to the description, the controller 9 as the calculation and determination unit calculates the position calculation value θp* related to the absolute position of the main encoder 15 within one rotation based on the following equation (8) using the detected position detection value θs of the absolute position.

[0071] θp*=MOD[{(θs×α×β))}÷360]×360

[0072] Formula (8)

[0073] Next, in step S33 , the controller 9 calculates the absolute value θpd of the deviation between the position detection value θs of the main encoder 15 and the position calculation value θp* based on the following equation (9).

[0074] θpd=|θp*-θp|

[0075] Formula (9)

[0076] Then, in step S34, the controller 9 determines whether the absolute value θpd of the deviation is greater than the third error determination value θj3. Here, the absolute value θpd of the deviation represents the offset of the detection position between the main encoder 15 and the sub-encoder 25. In an ideal state without backlash of the speed reducer 20 and various detection errors, the absolute value θpd of the deviation is 0. Therefore, the third error determination value θj3 is a value greater than zero predetermined by the operator.

[0077] When it is determined in step S34 that the absolute value θpd of the deviation is greater than the third error determination value θj3, it is determined that the relative position between the main encoder 15 and the sub-encoder 25 is abnormal (step S35). In this case, as the setting position of the main encoder 15 and / or the sub-encoder 25 is abnormal, the controller 9 stops the operation of the motor 10. At this time, this meaning may also be displayed on a display unit (not shown), such as a screen of a teaching control panel.

[0078] On the other hand, when it is determined in step S34 that the absolute value θpd of the deviation is not greater than the third error determination value θj3, it is determined that the relative position between the main encoder 15 and the sub-encoder 25 is normal (step S36), and the processing ends.

[0079] In this way, the process of determining whether there is an abnormality in the relative position between the main encoder 15 and the sub-encoder 25 in the second embodiment of the present disclosure does not require an additional battery. Therefore, in the second embodiment, the abnormality of the position of the main encoder 15 and / or the sub-encoder 25 can be simply detected without the need for an additional battery.

[0080] Furthermore, the computer program for executing the processing of the controller 9 as the calculation unit and the calculation determination unit may be provided in a form recorded on a computer-readable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium.

[0081] The method disclosed

[0082] 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; a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor; and a calculation unit, wherein the reduction ratio of the reducer is 1 / n, and n is a non-integer, and the calculation unit calculates a plurality of position calculation values ​​of the main encoder related to the absolute position of the motor shaft within one rotation based on the absolute position of the sub-encoder within one rotation, and the calculation unit calculates the total number of rotations of the sub-encoder based on the actual position value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the plurality of position calculation values.

[0083] According to a second aspect, in the first aspect, the calculation unit calculates the total number of rotations of the sub encoder based on an absolute value of a deviation between the actual position value and the plurality of position calculated values.

[0084] According to the third mode, in the first or second mode, when the minimum value among the absolute values ​​of the deviations between the actual position value and the plurality of position calculation values ​​is greater than a predetermined first error determination value, the calculation unit calculates the minimum value after correcting the plurality of position calculation values.

[0085] According to a fourth method, in any one of the first to third methods, when the minimum value among the absolute values ​​of the deviations between the actual position value and the multiple position calculation values ​​is not less than a predetermined second error judgment value that is smaller than the first error judgment value, the calculation unit calculates the total number of rotations of the sub-encoder.

[0086] According to a fifth embodiment, an actuator is provided, comprising: a motor; a reducer combined with the motor; a main encoder, which detects the position of a motor shaft of the motor; a sub-encoder, which detects the position of an output shaft of the reducer; and a calculation unit, wherein the reduction ratio of the reducer is 1 / n, and n is a non-integer, and the calculation unit calculates a plurality of position calculation values ​​of the main encoder related to the absolute position of the motor shaft within one rotation based on the absolute position of the sub-encoder within one rotation, and the calculation unit calculates the total number of rotations of the sub-encoder based on the actual position value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the plurality of position calculation values.

[0087] According to a sixth aspect, in the fifth aspect, the calculation unit calculates the total number of rotations of the sub encoder based on an absolute value of a deviation between the actual position value and the plurality of position calculated values.

[0088] According to the seventh mode, in the fifth or sixth mode, when the minimum value among the absolute values ​​of the deviations between the actual position value and the plurality of position calculation values ​​is greater than a predetermined first error judgment value, the calculation unit calculates the minimum value after correcting the plurality of position calculation values.

[0089] According to the eighth method, in any one of the fifth to seventh methods, when the minimum value among the absolute values ​​of the deviations between the actual position value and the multiple position calculation values ​​is not less than a predetermined second error judgment value that is smaller than the first error judgment value, the calculation unit calculates the total number of rotations of the sub-encoder.

[0090] According to the ninth method, 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, the reduction ratio of the reducer is 1 / n, n is a non-integer, based on the absolute position of the sub-encoder within one rotation, a plurality of position calculation values ​​of the main encoder related to the absolute position of the motor shaft within one rotation are calculated, and based on the actual position value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the plurality of position calculation values, the total number of rotations of the sub-encoder is calculated.

[0091] According to a tenth aspect, in the ninth aspect, the total number of rotations of the sub encoder is calculated based on the absolute value of the deviation between the actual position value and the plurality of position calculated values.

[0092] According to the eleventh embodiment, in the ninth or tenth embodiment, when the minimum value among the absolute values ​​of the deviations between the actual position value and the plurality of position calculation values ​​is greater than a predetermined first error judgment value, the calculation unit calculates the minimum value after correcting the plurality of position calculation values.

[0093] According to the twelfth method, in any one of the ninth to eleventh methods, when the minimum value among the absolute values ​​of the deviations between the actual position value and the multiple position calculation values ​​is not less than a predetermined second error judgment value that is smaller than the first error judgment value, the total number of rotations of the sub-encoder is calculated.

[0094] According to the thirteenth method, a position detection system is provided, which comprises: a main encoder, which detects the position of a motor shaft of a motor; a sub-encoder, which detects the position of an output shaft of a reducer combined with the motor; and a calculation and judgment unit, which calculates a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft within one rotation detected by the sub-encoder, and the calculation and judgment unit also determines that there is an abnormality in the position of at least one of the main encoder and the sub-encoder when the absolute value of the deviation between the position actual value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the position calculation value is greater than a predetermined value.

[0095] According to a fourteenth aspect, an actuator is provided, comprising: a motor; a reducer combined with the motor; a main encoder, which detects the position of a motor shaft of the motor; a sub-encoder, which detects the position of an output shaft of the reducer; and a calculation and determination unit, which calculates a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft within one rotation detected by the sub-encoder, and the calculation and determination unit also determines that there is an abnormality in the position of at least one of the main encoder and the sub-encoder when the absolute value of the deviation between the position actual value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the position calculation value is greater than a predetermined value.

[0096] According to a fifteenth embodiment, a position detection method of a position detection system is provided, 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, and calculates a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft detected by the sub-encoder within one rotation, and when the absolute value of the deviation between the position actual value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the position calculation value is greater than a predetermined value, it is determined that there is an abnormality in the position of at least one of the main encoder and the sub-encoder.

[0097] The embodiments of the present disclosure are 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 patent protection scope 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 applies to the case where numerical values ​​or mathematical formulas are used in the description of the above-mentioned embodiments. In addition, appropriate combinations of several embodiments in the above-mentioned embodiments are included in the scope of the present disclosure.

[0098] Description of Reference Numerals

[0099] 1.2 connecting rod

[0100] 3. Machinery (Robot)

[0101] 5. Position detection system

[0102] 6 Actuator

[0103] 7 Memory

[0104] 8 Batteries

[0105] 9 Controller (Calculation Unit, Calculation and Judgment Unit)

[0106] 10 Motor

[0107] 11 Stator

[0108] 12 rotors

[0109] 13 Motor shaft

[0110] 15 Main encoder

[0111] 16. Detection Department

[0112] 20 reducer

[0113] 23 Output shaft

[0114] 25 pairs of encoders

[0115] 26 Detection Department

[0116] 50 built-in brake

[0117] θj1 first error judgment value

[0118] θj2 Second error judgment value

[0119] θj3 is the third error determination value.

Claims

1. A position detection system, characterized in that: have: a main 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 Computing Department, The reduction ratio of the reducer is 1 / n, where n is a non-integer. The calculation unit calculates a plurality of position calculation values ​​related to the absolute position of the main encoder within one rotation of the motor shaft based on the absolute position of the sub encoder within one rotation, The calculation unit calculates the total number of rotations of the sub encoder based on an actual position value related to an absolute position of the motor shaft within one rotation detected by the main encoder and the plurality of position calculation values.

2. The position detection system according to claim 1, characterized in that: The calculation unit calculates the total number of rotations of the sub encoder based on an absolute value of a deviation between the actual position value and the plurality of calculated position values.

3. The position detection system according to claim 1 or 2, characterized in that: When a minimum value among the absolute values ​​of the deviations between the position actual value and the plurality of position calculated values ​​is greater than a predetermined first error determination value, the calculation section calculates the minimum value after correcting the plurality of position calculated values.

4. The position detection system according to any one of claims 1 to 3, characterized in that: The calculation unit calculates the total number of rotations of the sub encoder when a minimum value among the absolute values ​​of the deviations between the actual position value and the plurality of calculated position values ​​is not less than a predetermined second error determination value that is smaller than the first error determination value.

5. An actuator, characterized in that: have: motor; a reducer combined with the motor; a primary encoder that detects the position of a motor shaft of the motor; A secondary encoder, which detects the position of the output shaft of the reducer; as well as Computing Department, The reduction ratio of the reducer is 1 / n, where n is a non-integer. The calculation unit calculates a plurality of position calculation values ​​related to the absolute position of the main encoder within one rotation of the motor shaft based on the absolute position of the sub encoder within one rotation, The calculation unit calculates the total number of rotations of the sub encoder based on an actual position value related to an absolute position of the motor shaft within one rotation detected by the main encoder and the plurality of position calculation values.

6. The actuator according to claim 5, characterized in that The calculation unit calculates the total number of rotations of the sub encoder based on an absolute value of a deviation between the actual position value and the plurality of calculated position values.

7. The actuator according to claim 5 or 6, characterized in that: When a minimum value among the absolute values ​​of the deviations between the position actual value and the plurality of position calculated values ​​is greater than a predetermined first error determination value, the calculation section calculates the minimum value after correcting the plurality of position calculated values.

8. The actuator according to any one of claims 5 to 7, characterized in that The calculation unit calculates the total number of rotations of the sub encoder when a minimum value among the absolute values ​​of the deviations between the actual position value and the plurality of calculated position values ​​is not less than a predetermined second error determination value that is smaller than the first error determination value.

9. A position detection method of a position detection system, The position detection system comprises: 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, It is characterized in that The reduction ratio of the reducer is 1 / n, where n is a non-integer. Based on the absolute position of the sub-encoder within one rotation, a plurality of position calculation values ​​of the main encoder related to the absolute position of the motor shaft within one rotation are calculated, The total number of rotations of the sub-encoder is calculated based on the position actual value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the plurality of position calculation values.

10. The position detection method according to claim 9, characterized in that: The total number of rotations of the sub-encoder is calculated based on the absolute value of the deviation between the actual position value and the plurality of calculated position values.

11. The position detection method according to claim 9 or 10, characterized in that: When a minimum value among the absolute values ​​of the deviations between the position actual value and the plurality of position calculated values ​​is greater than a predetermined first error determination value, the calculation section calculates the minimum value after correcting the plurality of position calculated values.

12. The position detection method according to any one of claims 9 to 11, characterized in that: When a minimum value among the absolute values ​​of the deviations between the actual position value and the plurality of calculated position values ​​is not less than a predetermined second error determination value that is smaller than the first error determination value, the total number of rotations of the sub encoder is calculated.

13. A position detection system, characterized in that: have: a main 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 Calculation and judgment unit, The calculation and determination unit calculates a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft within one rotation detected by the sub-encoder. The calculation and determination unit also determines that there is an abnormality in the position of at least one of the main encoder and the sub-encoder when the absolute value of the deviation between the actual position value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the position calculation value is greater than a predetermined value.

14. An actuator, characterized in that: have: motor; a reducer combined with the motor; a primary encoder that detects the position of a motor shaft of the motor; A secondary encoder, which detects the position of the output shaft of the reducer; as well as Calculation and judgment unit, The calculation and determination unit calculates a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft within one rotation detected by the sub-encoder. The calculation and determination unit also determines that there is an abnormality in the position of at least one of the main encoder and the sub-encoder when the absolute value of the deviation between the actual position value related to the absolute position of the motor shaft within one rotation detected by the main encoder and the position calculation value is greater than a predetermined value.

15. A position detection method of a position detection system, The position detection system comprises: 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, It is characterized in that calculating a position calculation value related to the absolute position of the motor shaft within one rotation based on the absolute position of the output shaft within one rotation detected by the sub-encoder, When the absolute value of the deviation between the actual position value detected by the main encoder and the calculated position value related to the absolute position of the motor shaft within one rotation is greater than a predetermined value, it is determined that there is an abnormality in the position of at least one of the main encoder and the sub-encoder.

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