Position detection system, actuator and position detection method

Abstract

A position detection system (5) comprising a primary encoder (15) that detects the position of a motor shaft, a secondary encoder (25) that detects the position of an output shaft (23) of a reduction gear (20), and a computation unit (9). The reduction ratio of the reduction gear (20) is 1 / n, where n is a non-integer. The computation unit (9) determines a plurality of calculated position values ​​with respect to an absolute position in one revolution of the motor shaft (13) using the primary encoder (15) based on an absolute position in one revolution of the secondary encoder (25), and calculates a total number of revolutions of the secondary encoder (25) based on an actual position value with respect to the absolute position in one revolution of the motor shaft (13) detected by the primary encoder (15) and the plurality of calculated position values.

Description

TECHNICAL FIELD

[0001] The present invention relates to a position detection system, an actuator and a method for position detection. STATE OF THE ART

[0002] Actuators consist of a servomotor and a reduction gear connected to each other. A primary encoder is connected to a motor shaft of the servomotor to detect an absolute position within one revolution of the motor shaft and the total number of revolutions of the motor shaft. Similarly, a secondary encoder is connected to an output shaft of the reduction gear to detect an absolute position within one revolution of the output shaft and the total number of revolutions of the output shaft (see JP2007113932A). The information detected by each encoder is stored in a memory.

[0003] Japanese Patent Publication JP2006300596A proposes a method in which the reduction ratio of a reduction gear is defined as 1 / n (where n is a non-integer), the value of a “judgment criterion” is calculated from the position of a secondary encoder, and a ±1 rotation of the secondary encoder is determined based on the value of the judgment criterion and the result of determining whether the position of the primary encoder is positive or negative. [CITATION LIST][PATENT LITERATURE] PTL 1: JP2007113932A PTL2: JP2006300596A SUMMARY OF THE INVENTION [TECHNICAL PROBLEM]

[0004] However, in the method of Japanese Patent Publication (Kokai) No. 2006-300596, a battery-free absolute encoder cannot be achieved when the output shaft makes two or more revolutions.

[0005] What is desired is a position detection system that can be used without an additional battery even when the output shaft makes two or more revolutions. [SOLVING THE PROBLEM]

[0006] According to a first aspect of the present invention, a position detection system is provided, comprising a primary encoder for detecting a position of a motor shaft of a motor, a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, and a calculation unit, wherein a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the calculation unit determines a plurality of calculated position values ​​with respect to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and the calculation unit determines a total number of revolutions of the secondary encoder based on an actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder,and the multitude of calculated position values.

[0007] According to another aspect of the present invention, a position detection system comprises a primary encoder for detecting a position of a motor shaft of a motor, a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, and a calculation / verification unit, wherein the calculation / verification unit calculates calculated position values ​​with respect to an absolute position in one revolution of the motor shaft based on an absolute position in one revolution of the output shaft detected by the secondary encoder, and the calculation / verification unit further determines that an abnormality exists in the position of the primary encoder and / or the secondary encoder when an absolute value of a deviation between an actual position value with respect to an absolute position in one revolution of the motor shaft detected by the primary encoderand the calculated position value is equal to or greater than a predetermined value.

[0008] The object, features and advantages of the present invention will become apparent from the following description of the embodiments taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic side view of a position detection system based on a first embodiment of the present invention. Fig. 2 is a first flowchart showing the operation of the Fig. 1 shows the position detection system. Fig. 3 is a view showing the relationship between the position of the output shaft and the position of the input shaft. Fig. 4 is another view showing the relationship between the position of the output shaft and the position of the input shaft. Fig. 5 is a second flowchart showing the operation of a position detection system based on a second embodiment. DESCRIPTION OF THE EMBODIMENTS

[0009] The embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, corresponding components are designated by the same reference numerals.

[0010] Fig. 1 is a schematic side view of a position detection system based on a first embodiment of the present invention. The position detection system 5 is incorporated into a machine 3 having a shaft, such as a robot 3. Although the case where the position detection system 5 is incorporated into the robot 3 will be described below, the same applies to the case where the position detection system 5 is incorporated into another machine 3 having a shaft, such as a machine tool.

[0011] In Fig. 1, an actuator 6 arranged in a link 1 comprises a motor 10, e.g., a servomotor, and a reduction gear 20 coupled to a motor shaft 13 of the motor 10, which are connected to each other. The motor 10 comprises a rotor 12 that rotates together with the motor shaft 13, and a stator 11 arranged to surround the rotor 12. The end face of an output shaft 23 of the reduction gear 20 is connected to a link 2. In this way, the actuator 6, formed from the motor 10 and the reduction gear 20, rotates the link 2 relative to the link 1 within a predetermined operating range to determine its positioning. The reduction ratio n of the reduction gear 20 is a positive, non-integer, e.g., 1 / 2. B. n = α + 1 / β (where α and β are positive numbers greater than 1).

[0012] The motor shaft 13 is, for example, a hollow shaft, at the rear end of which a primary encoder 15 is arranged, which comprises a rotating disk 15A. The primary encoder 15 is, for example, an incremental encoder and outputs A-phase, B-phase, and Z-phase signals. The output signals are detected by a detection unit 16, which detects an absolute position θp within one revolution of the motor shaft 13 and the total number of revolutions using a known method. The detected information is stored in a memory 7, for example, a volatile memory.

[0013] The output shaft 23 extends through the hollow motor shaft 13 toward the side of the motor 10, and a secondary encoder 25, including a rotating disk 25A, is arranged at a 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 signals are detected by a detection unit 26, which detects an absolute position θs within one revolution of the output shaft 23 and the total number of revolutions i according to a known method. The detected information is stored in a memory 7, e.g., a temporary memory.

[0014] The information stored in the memory 7 can be stored for a certain period of time thanks to a battery 8, e.g. a button battery or a capacitor. Fig. The position detection system 5 shown in Figure 1 comprises a common memory 7 and a common battery 8 for the primary encoder 15 and the secondary encoder 25. However, the primary encoder 15 and the secondary encoder 25 may each have their own memory and battery.

[0015] The information stored in memory 7 is transmitted to a control unit 9. The control unit 9 may be a control unit for controlling the machine 3 or an LSI arranged on the encoders 15 and 25. Based on the transmitted information, the control unit 9 drives and controls the motor 10 and performs a positioning operation to position the link 2 in a target position relative to the link 1. Furthermore, a brake mechanism 50 arranged on the outer surface of the motor shaft 13 is actuated in response to a command from the control unit 9 to stop the motor shaft 13. In addition, the control unit 9 also serves to turn on the primary encoder 15 and the secondary encoder 25 during operation of the machine 3.

[0016] The control unit 9 additionally serves as a calculation unit for calculating a plurality of calculated position values ​​with respect to the absolute position of the primary encoder 13 in one revolution of the motor shaft 13 based on the absolute position of the secondary encoder 25 in one revolution and for calculating a total number of revolutions of the secondary encoder 25 based on the actual position value with respect to the absolute position in one revolution of the motor shaft 13 detected by the primary encoder 15 and the plurality of calculated position values.

[0017] The control unit 9 further serves as a calculation / checking unit for calculating a calculated position value with respect to an absolute position in one revolution of the motor shaft 13 based on an absolute position of the output shaft 23 in one revolution detected by the secondary encoder 25, and for determining that there is an abnormality in the position of the primary encoder 15 and / or the secondary encoder 25 when an absolute value of a deviation of the actual position value with respect to the absolute position in one revolution of the motor shaft 13 detected by the primary encoder 15 and the calculated position value is equal to or greater than a predetermined value.

[0018] Fig. 2 is a first flowchart showing the operation of the Fig. 1. The contents of the Fig. 2 is stored in a memory unit (not shown) in the control unit 9 or in the memory 7. The Fig. 2 are executed accordingly when the motor 10 is driven.

[0019] First, in step S11, the secondary encoder 25 detects the absolute position θs within one revolution of the output shaft 23. Next, in step S12, the control unit 9 uses the detected absolute position θs to calculate a calculated position value θp*(i) with respect to the absolute position of the primary encoder 15 in one revolution, based on the following formula (1) (where i is a positive number equal to or less than β): θp∗(i)=MOD[{(θs×(α+1 / β)+(360 / β)+(i−1))}÷360]×360

[0020] Note that “MOD []” refers to a function for calculating the remainder of a division.

[0021] Fig. 3 is a view showing the relationship between the position of the output shaft and the position of the input shaft. In Fig. In Figure 3, the horizontal axis represents the position of the output shaft 23 of the reduction gear 20, and the vertical axis represents the position of the drive shaft. The "drive shaft position" is the position of the drive shaft input to the secondary encoder 25. Since the secondary encoder 25 is located downstream of the primary encoder 15 in this description, the "drive shaft position" can also be represented as the position of the rotating disk 15A of the primary encoder 15 or the position of the motor shaft 13. Fig. 3, both the horizontal and vertical axes are shown in degrees. As described above, the reduction ratio n of the reduction gear 20 is n = α+1 / β (where α and β are positive numbers greater than 1), and in the Fig. In the example shown in Figure 3, α = 2 and β = 3.

[0022] In Fig. 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 makes its first revolution. The dashed line L2 represents the position of the input shaft when the output shaft 23 makes its second revolution. The dashed-dotted line L3 represents the position of the input shaft when the output shaft 23 makes its third revolution.

[0023] As from Fig. As can be seen from Figure 3, the position detection system 5 of the first embodiment can detect up to β revolutions of the output shaft 23. The position of the output shaft 23 differs between the first and second revolutions. In the first embodiment, the total number of revolutions of the output shaft 23 is determined by using the difference between the position at the first revolution and the position at the second revolution.

[0024] Since β in the Fig. 3 shown example = 3, θp*(1), θp*(2) and θp*(3) on the vertical axis are in Fig. 3. These θp*(i) are values ​​on the vertical axis corresponding to the intersection points between the absolute position θs of the output shaft 23 and the three lines L1, L2 and L3.

[0025] In step S13, the control unit 9 acquires a position detection value θp relative to the absolute position in one revolution of the motor shaft 13, which is acquired by the primary encoder 15. The control unit 9 then calculates a plurality of absolute values ​​θd(i) (= |θp-θp*(i)|) of deviations between the position detection value θp and the plurality of calculated position values ​​θp*(i). Fig. 3 the absolute values ​​of the deviations θd(1) (= |θp-θp*(1)|), θd(2) (= |θp-θp*(2)|) and θd(3) (= |θp-θp*(3)|) are marked by arrows.

[0026] First, in step S14, the control unit 9 selects a minimum value Minθd(i) from the plurality of absolute values ​​θd(1), θd(2) and θd(3) of Fig. 3 out. Since θd(2) < θd(1) < θd(3) in the in Fig. In the example shown in Figure 3, θd(2) corresponds to the minimum value Minθd(i).

[0027] In step S15, the control unit 9 compares the selected minimum value Minθd(i) with a first misjudgment value θj1. The first misjudgment value θj1 is calculated in advance based on the following formula (2): θj1=360 / β−n⋅θsa_max−θpa_max−θnois_max

[0028] θsa represents the detection accuracy, which is determined according to the characteristics of the secondary encoder 25, and θsa_max is the value at which the detection accuracy is lowest. θpa represents the detection accuracy, which is determined according to the characteristics of the primary encoder 15, and θpa_max is the value at which the detection accuracy is lowest. θnois represents the width of the interference of the position detection system 5, and θnois_max is the corresponding maximum value.

[0029] If it is determined in step S15 that the minimum value Minθd(i) is not greater than the first misjudgment value θj1, it is determined that no abnormality exists, and the process proceeds to step S19. Then, in step S19, the minimum value Minθd(i) is compared with a second misjudgment value θj2. The second misjudgment value θj2 is calculated in advance based on the following formula (3): θj2≥θj1−360=n⋅θsa_max+θpa_max+θnois_max

[0030] As can be seen from formula (3), the second misjudgment value θj2 is smaller than the first misjudgment value θj1.

[0031] If it is determined that the minimum value Minθd(i) is not less than the second misjudgment value θj2, the process proceeds to step S21. In step S21, it is determined that there is an abnormality in the position of the primary encoder 15 and / or the secondary encoder 25. The control unit 9 then determines that this is a detection error and stops the operation of the motor 10. At this time, this can be displayed on a display unit (not shown), such as a screen of a teaching pendant.

[0032] If, however, it is determined in step S19 that the minimum value Minθd(i) is smaller than the second misjudgment value θj2, the process proceeds to step S20. In step S20, the control unit 9 calculates the total number of revolutions of the secondary encoder 25 based on the minimum value Minθd(i). Since θd(i) is the minimum value Minθd(i) in the Fig. 3, it is assumed that the total number of revolutions i is 2.

[0033] In this way, the process of detecting the total number of revolutions of the secondary encoder 25 of the first embodiment of the present invention does not require an additional battery. Therefore, in the first embodiment of the present invention, the position detection system 5 can be used even when the output shaft 23 rotates two or more times without requiring an additional battery. In other words, even when the encoders 15, 25 are moved in a situation where the controller 9 does not supply power to the encoders 15, 25, the position detection system 5 of the first embodiment can detect the total number of revolutions of the output shaft 23.

[0034] If it is determined in step S15 that the minimum value Minθd(i) is larger than the first misjudgment value θj1, the process proceeds to step S16. Fig. 4 is another view showing the relationship between the position of the output shaft and the position of the input shaft, similar to Fig. 3. The case where it is determined in step S15 that the minimum value Minθd(i) is greater than the first misjudgment value θj1 is, for example, a situation like that shown in Fig. Example shown in Figure 4.

[0035] In Fig. 4, the absolute position θs in one revolution of the output shaft 23 is at a different location than in Fig. 3. If the absolute values ​​of the deviation θd(1) (= |θp-θp*(1)|), θd(2) (= |θp-θp*(2)|) and θd(3) (= |θp-θp*(3)|) of the Fig. 4 are compared with each other, θd(3) < θd(2) < θd(1).

[0036] In Fig. 4, the minimum value Minθd(i) should be θd(1), and it is clear that θd(3) is erroneously set as the minimum value Minθd(i). However, since the position of the motor shaft 13 relative to the primary encoder 15 is close to 0° (close to 360°), it is difficult to make such a determination. Therefore, assuming that the position of the motor shaft 13 relative to the primary encoder 15 is close to 0°, the controller 9 performs a position jump correction in step S16 based on the absolute value of the deviation θd(i) detected in step S13.

[0037] The formula (4) used in the correction of the position jump is as follows: θd(i)=|θp−θp∗(i)|=360−360(i−l) / β−nθsa−θpa−θnois

[0038] As a result, θd(1), θd(2) and θd(3) are corrected according to the following formulas (5) to (7): θd(1)=|θp−θp(1)|=360−nθsa−θpa−θnois θd(2)=|θp−θp*(2)|=240−nθsa−θpa−θnois θd(3)=|θp-θp∗(3)|=120−nθsa−θpa−θnois

[0039] In formulas (4) to (7), θsa and θpa are about 0.01 degrees, and θnois is several degrees.

[0040] In step S17, the control unit 9 selects the minimum value Minθd(i) from the plurality of absolute values ​​θd(i) corrected in this way. In the Fig. In the example shown in Figure 4, the minimum value Minθd(i) is the corrected absolute value θd(1). By correcting the position jump in this way, the corrected minimum value Minθd(i) (the corrected absolute value θd(1) of Fig. 4) selected.

[0041] In step S18, the corrected minimum value Minθd(i) after correction is set as the minimum value Minθd(i). The process then proceeds to step S20, and the total number of revolutions of the secondary encoder 25 is calculated in accordance with the new minimum value Minθd(i) in the same manner as described above. Since θd(i) is the minimum value Minθd(i) in the Fig. 4, it is assumed that the total number of revolutions i is 1.

[0042] With this configuration, the total number of revolutions of the secondary encoder 25 can be accurately calculated even if the position of the motor shaft 13 with respect to the primary encoder 15 is close to 0°.

[0043] Fig. Fig. 5 is a second flowchart showing the operation of the position detection system according to a second embodiment. The content of the Fig. 5 is stored in a memory unit (not shown) in the control unit 9 or in the memory 7. The Fig. 5 is suitably executed when the motor 10 is driven.

[0044] The reduction ratio n of the reduction gear 20 of the second embodiment is not limited to the above. Specifically, the reduction ratio n in this case may be 1 / α (where α is a positive number greater than 1). The second embodiment also includes the case where an additional reduction gear (not shown) is arranged between the output shaft 23 and the secondary encoder 25, and the total reduction ratio of the reduction gear 20 and the additional reduction gear is 1 / α' (α' is a positive number greater than 1).

[0045] First, in step S31, the secondary encoder 25 detects a position detection value θs with respect to the absolute position in one revolution of the output shaft 23 in the same manner as described above. In step S32, the control unit 9 as a calculation / checking unit calculates in the same manner as in Fig.3 described the calculated position value θp* with respect to the absolute position of the primary encoder 15 in one revolution based on the following formula (8) using the position detection value θs of the detected absolute position. θp∗=MOD[{((θs×α×β))}÷360]×360

[0046] Next, in step S33, the control unit 9 calculates the absolute value θpd of the deviation between the position detection value θs of the primary encoder 15 and the calculated position value θp* using the following formula (9): θpd=|θp∗−θp|

[0047] In step S34, the controller 9 determines whether the absolute value of the deviation θpd is greater than the third misjudgment value θj3. The absolute value of the deviation θpd represents a deviation in the detection position between the primary encoder 15 and the secondary encoder 25. In an ideal state with no backlash of the reduction gear 20 and various detection errors, the absolute value of the deviation θpd is 0. Therefore, the third misjudgment value θj3 is a value specified by the operator that is greater than zero.

[0048] If it is determined in step S34 that the absolute value of the deviation θpd is greater than the third misjudgment value θj3, it is determined that the relative position between the primary encoder 15 and the secondary encoder 25 is abnormal (step S35). In this case, it is determined that there is an abnormality in the target position of the primary encoder 15 and / or the secondary encoder 25, and the control unit 9 stops the operation of the motor 10. At this time, this can be displayed on a display unit (not shown), such as a screen of a teaching pendant.

[0049] Conversely, if it is determined in step S34 that the absolute value of the deviation θpd is not larger than the third misjudgment value θj3, it is determined that the relative position between the primary encoder 15 and the secondary encoder 25 is normal (step S36), and the process ends.

[0050] In this way, the method for determining whether or not there is an abnormality in the relative position between the primary encoder 15 and the secondary encoder 25 of the present invention does not require an additional battery. Thus, in the second embodiment, an abnormality in the position of the primary encoder 15 and / or the secondary encoder 25 can be easily detected without requiring an additional battery.

[0051] Furthermore, the computer program for executing the processing of the control device 9 as a calculation unit and a calculation / verification 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. ASPECTS OF THE PRESENT INVENTION

[0052] According to a first aspect, a position detection system is provided, comprising a primary encoder for detecting a position of a motor shaft of a motor, a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, and a calculation unit, wherein a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the calculation unit determines a plurality of calculated position values ​​with respect to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and the calculation unit determines a total number of revolutions of the secondary encoder based on an actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder,and the multitude of calculated position values.

[0053] According to a second aspect, the calculation unit calculates the total number of revolutions of the secondary encoder based on an absolute deviation between the actual position value and the plurality of calculated position values.

[0054] According to a third aspect, in the first or second aspect, when a minimum value of the absolute value of a deviation of the actual position value and the plurality of calculated position values ​​is larger than a predetermined first error estimation value, the calculation unit calculates the minimum value after correcting the plurality of calculated position values.

[0055] According to a fourth aspect, the calculation unit calculates a total number of revolutions of the secondary encoder when a minimum value of the absolute value of the deviation between the actual position value and the plurality of calculated position values ​​is not less than a predetermined second error estimation value which is less than the first error estimation value.

[0056] According to a fifth aspect, an actuator is provided comprising a motor, a reduction gear coupled to the motor, a primary encoder for detecting a position of a motor shaft of the motor, a secondary encoder for detecting a position of an output shaft of the reduction gear, and a calculation unit, wherein a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the calculation unit determines a plurality of calculated position values ​​with respect to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and the calculation unit determines a total number of revolutions of the secondary encoder based on an actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder,and the multitude of calculated position values.

[0057] According to a sixth aspect, the calculation unit calculates the total number of revolutions of the secondary encoder based on an absolute deviation between the actual position value and the plurality of calculated position values.

[0058] According to a seventh aspect, the calculation unit calculates the minimum value after correcting the plurality of calculated position values ​​when a minimum value of the absolute value of a deviation of the actual position value and the plurality of calculated position values ​​is larger than a predetermined first error estimation value.

[0059] According to an eighth aspect, the calculation unit calculates the total number of revolutions of the secondary encoder when a minimum value of the absolute value of the deviation of the actual position value and the plurality of calculated position values ​​is not less than a predetermined second error estimation value which is less than the first error estimation value.

[0060] According to a ninth aspect, a position detection method is provided for a position detection system comprising a primary encoder for detecting a position of a motor shaft of a motor and a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, wherein a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the method comprising the steps of: calculating a plurality of calculated position values ​​with respect to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and calculating a total number of revolutions of the secondary encoder based on an actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder,and the multitude of calculated position values.,

[0061] According to a tenth aspect, the method further comprises calculating a total number of revolutions of the secondary encoder based on an absolute deviation between the actual position value and the plurality of calculated position values.

[0062] According to an eleventh aspect, the method further comprises that, when a minimum value of the absolute value of the deviation of the actual position value and the plurality of calculated position values ​​is larger than a predetermined first error estimation value, the calculation unit calculates the minimum value after correcting the plurality of calculated position values.

[0063] According to a twelfth aspect, the method further comprises calculating a total number of revolutions of the secondary encoder when a minimum value of the absolute value of the deviation between the actual position value and the plurality of calculated position values ​​is not less than a predetermined second error estimation value that is less than the first error estimation value.

[0064] According to a thirteenth aspect, a position detection system is provided, comprising a primary encoder for detecting a position of a motor shaft of a motor, a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, and a calculation / verification unit, wherein a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the calculation / verification unit calculates calculated position values ​​with respect to an absolute position in one revolution of the motor shaft based on an absolute position in one revolution of the output shaft detected by the secondary encoder, and the calculation / verification unit further determines that there is an abnormality in the position of the primary encoder and / or the secondary encoder,when an absolute value of a deviation between an actual position value with respect to an absolute position in one revolution of the motor shaft detected by the primary encoder and the calculated position value is equal to or greater than a predetermined value.

[0065] According to a fourteenth aspect, an actuator is provided comprising a motor, a reduction gear coupled to the motor, a primary encoder for detecting a position of a motor shaft of the motor, a secondary encoder for detecting a position of an output shaft of the reduction gear, and a calculation / verification unit, wherein the calculation / verification unit calculates a calculated position value with respect to an absolute position in one revolution of the motor shaft based on an absolute position of the output shaft in one revolution detected by the secondary encoder, and the calculation / verification unit further determines that there is an abnormality in the position of the primary encoder and / or the secondary encoder when an absolute value of a deviation of the actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoderand the calculated position value is equal to or greater than a predetermined value.

[0066] According to a fifteenth aspect, a position detection method is provided for a position detection system comprising a primary encoder for detecting a position of a motor shaft of a motor and a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, the method comprising the steps of: calculating a calculated position value with respect to an absolute position in one revolution of the motor shaft based on an absolute position of the output shaft in one revolution detected by the secondary encoder, and determining that an abnormality exists in the position of at least one of the primary encoder and the secondary encoder when an absolute value of a deviation of the actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoderand the calculated position value is equal to or greater than a predetermined value.

[0067] Although the embodiments of the present invention have been described in detail, the present invention is not limited to the individual embodiments described above. Various additions, replacements, changes, or partial deletions may be made to these embodiments within the spirit of the invention or within the scope of the idea and intent of the present invention, which can be understood from the contents described in the claims and their subjects. For example, the order of each operation and the order of each method of the above-described embodiments are presented as examples and are not limited to them. The same applies when numerical values ​​or formulas are used in the description of the above-described embodiments. Furthermore, suitable combinations of some of the above-described embodiments are included within the scope of the present invention. LIST OF REFERENCE SYMBOLS 1,2 Link 3 Machine (robot) 5 Position detection system 6 Actuator 7 storage 8 Battery 9 Control unit (calculation unit, calculation / verification unit) 10 Engine 11 Stator 12 Rotor 13 Motor shaft 15 primary encoder 16 Detection unit 20 reduction gears 23 Output shaft 25 secondary encoder 26 Detection unit 50 Brake mechanism θj1 first miscalculation value θj2 second miscalculation value θj3 third misjudgement value QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2007113932A [0002, 0003] JP 2006300596A

[0003] JP 2006-300596

[0004]

Claims

[1] Position detection system, comprising: a primary encoder for detecting a position of a motor shaft of a motor, a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, and a calculation unit, where a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the calculation unit determines a plurality of calculated position values with respect to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and the calculation unit calculates a total number of revolutions of the secondary encoder based on an actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder and the plurality of calculated position values. [2] The position detection system according to claim 1, wherein the calculation unit calculates the total number of revolutions of the secondary encoder based on an absolute deviation between the actual position value and the plurality of calculated position values. [3] The position detecting system according to claim 1 or 2, wherein when a minimum value of the absolute value of a deviation of the actual position value and the plurality of calculated position values is larger than a predetermined first error estimation value, the calculating unit calculates the minimum value after correcting the plurality of calculated position values. [4] The position detecting system according to any one of claims 1 to 3, wherein, when a minimum value of the absolute value of the deviation between the actual position value and the plurality of calculated position values is not less than a predetermined second error estimation value which is smaller than the first error estimation value, the calculating unit calculates a total number of revolutions of the secondary encoder. [5] Actuator comprising: an engine, a reduction gear coupled to the motor, a primary encoder for detecting a position of a motor shaft of the motor, a secondary encoder for detecting a position of an output shaft of the reduction gear, and a calculation unit, where a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the calculation unit determines a plurality of calculated position values with respect to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and the calculation unit calculates a total number of revolutions of the secondary encoder based on an actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder and the plurality of calculated position values. [6] The actuator according to claim 5, wherein the calculation unit calculates the total number of revolutions of the secondary encoder based on an absolute deviation between the actual position value and the plurality of calculated position values. [7] The actuator according to claim 5 or 6, wherein when a minimum value of the absolute value of a deviation of the actual position value and the plurality of calculated position values is larger than a predetermined first error estimation value, the calculation unit calculates the minimum value after correcting the plurality of calculated position values. [8] The actuator according to any one of claims 5 to 7, wherein, when a minimum value of the absolute value of the deviation of the actual position value and the plurality of calculated position values is not less than a predetermined second error estimation value which is less than the first error estimation value, the calculation unit calculates a total number of revolutions of the secondary encoder. [9] A position detection method for a position detection system comprising a primary encoder for detecting a position of a motor shaft of a motor and a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, wherein a reduction ratio of the reduction gear is equal to 1 / n, where n is a non-integer, the method comprising the following steps: Calculating a plurality of calculated position values relative to an absolute position in one revolution of the motor shaft with the primary encoder based on an absolute position in one revolution of the secondary encoder, and Calculating a total number of revolutions of the secondary encoder based on an actual position value relative to the absolute position in one revolution of the motor shaft detected by the primary encoder and the plurality of calculated position values. [10] A method for position detection according to claim 9, further comprising: Calculating a total number of revolutions of the secondary encoder based on an absolute deviation between the actual position value and the plurality of calculated position values. [11] A method for position detection according to claim 9 or 10, further comprising: when a minimum value of the absolute value of the deviation of the actual position value and the plurality of calculated position values is greater than a predetermined first error estimation value, the calculation unit calculates the minimum value after correcting the plurality of calculated position values. [12] A method for position detection according to any one of claims 9 to 11, further comprising: when a minimum value of the absolute value of the deviation between the actual position value and the plurality of calculated position values is not less than a predetermined second error estimation value which is less than the first error estimation value, calculating a total number of revolutions of the secondary encoder. [13] Position detection system, comprising: a primary encoder for detecting a position of a motor shaft of a motor, a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, and a calculation / verification unit, where the calculation / verification unit calculates calculated position values with respect to an absolute position in one revolution of the motor shaft based on an absolute position in one revolution of the output shaft detected by the secondary encoder, and the calculation / verification unit further determines that there is an abnormality in the position of the primary encoder and / or the secondary encoder when an absolute value of a deviation between an actual position value with respect to an absolute position in one revolution of the motor shaft detected by the primary encoder and the calculated position value is equal to or greater than a predetermined value. [14] Actuator comprising: an engine, a reduction gear coupled to the motor, a primary encoder for detecting a position of a motor shaft of the motor, a secondary encoder for detecting a position of an output shaft of the reduction gear, and a calculation / verification unit, where the calculation / verification unit calculates a calculated position value with respect to an absolute position in one revolution of the motor shaft based on an absolute position of the output shaft in one revolution detected by the secondary encoder, and the calculation / verification unit further determines that there is an abnormality in the position of the primary encoder and / or the secondary encoder when an absolute value of a deviation of the actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder and the calculated position value is equal to or greater than a predetermined value. [15] A position detection method for a position detection system comprising a primary encoder for detecting a position of a motor shaft of a motor and a secondary encoder for detecting a position of an output shaft of a reduction gear coupled to the motor, the method comprising the following steps: Calculating a calculated position value relative to an absolute position in one revolution of the motor shaft based on an absolute position of the output shaft in one revolution detected by the secondary encoder, and Determining that there is an abnormality in the position of the primary encoder and / or the secondary encoder when an absolute value of a deviation of the actual position value with respect to the absolute position in one revolution of the motor shaft detected by the primary encoder and the calculated position value is equal to or greater than a predetermined value.

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