Robot, drive unit for a robot, and positioning method

Abstract

The invention relates to a drive unit (1) for a robot (15), having an input shaft (3), a drive motor (4) for driving the input shaft (3), and a strain wave gearing (5) for transmitting from the input shaft (3) to an output shaft (11), wherein the strain wave gearing (5) has a wave generator (5a) operatively connected to the input shaft (3), a flexspline (5c), and a ring gear (5d) connectable to the output shaft (11), comprising a first sensor (6a) for detecting an angular position (Θ i ) of the input shaft (3) and a second sensor (6b) for detecting an angular position (Θ o ) of the output shaft (11). In order to enable an exact adjustment of the angular position of the output shaft (11) to each setpoint angular position in such a drive unit (1), it is proposed that the drive unit (1) has a third sensor (6c) for detecting an expansion (ω) of the flexspline (5c). The invention further relates to a robot (15) having such a drive unit (1) and a method for an exact adjustment of the angular position (Θ o ) of the output shaft (11) during positioning.

Description

Technical Field

[0001] This invention relates to a drive unit for a robot, the drive unit comprising: a drive shaft; a drive motor for driving the drive shaft; and a strain wave gear mechanism for transmission from the drive shaft to an output shaft, wherein the strain wave gear mechanism comprises: a wave generator operably connected to the drive shaft; a flexible ring; and a gear ring connectable to the output shaft. The drive unit includes: a first sensor for detecting the angular position of the drive shaft; and a second sensor for detecting the angular position of the output shaft. Furthermore, this invention relates to a robot having such a drive unit and a method for adjusting the angular position of the output shaft in such a drive unit. Background Technology

[0002] General-purpose drive units are known from the prior art and are specifically used in robotics, for example, to move robotic arms used in industrial, laboratory, or medical technologies. For this purpose, the drive unit is equipped with a strain wave gear mechanism to achieve a very high transmission ratio between the drive motor and the part of the robot to be moved, enabling precise movement of the robotic arm. The strain wave gear mechanism has a wave generator or wavemaker with a non-circular, particularly elliptical, cross-section and operates within a flexible ring, also known as a flexible gear, which is always deformable. The flexible ring has external teeth that engage only at two external points of its deformation with the internal teeth of a gear ring designed as the outer ring. Due to circumferential deformation, the engagement points also rotate, wherein the number of teeth in the flexible ring differs from the number of teeth in the gear ring, such that the gear ring is configured to perform a rotational motion significantly slower than that of the wave generator.

[0003] The drive motor is adjusted using a regulating process to move the output shaft to the desired angular position as precisely as possible. A first sensor and a second sensor serve as actual value generators, with the first sensor used for coarse positioning and the second sensor for fine positioning. Due to vibration and force input when a load is applied to the output side, the first sensor cannot provide sufficient accuracy and stability for fine positioning. An electric motor is typically used as the drive motor, and a rotary encoder is used as both the first and second sensors. Such a drive unit is known, for example, from KR 102061693 B1. A drive unit with a sensor for detecting expansion of the output shaft is also known from JP6334317B.

[0004] Disadvantageously, when the output shaft is moved, the flexible ring expands in a torsional manner, particularly during acceleration, where this expansion is superimposed on the angular position transmitted from the drive shaft to the output shaft. In this respect, the second sensor is not suitable for sufficiently precise adjustment of the output shaft position, at least within the angular distance where acceleration occurs, instead displaying measurements superimposed by the expansion, leading to overcorrection of the output shaft's angular position. In the angular range beyond the angular distance, the second sensor is only suitable for precise adjustment of the output shaft's angular position, provided that the flexible ring is known to expand continuously at a constant rate after acceleration. Summary of the Invention

[0005] The object of the present invention is to provide a drive unit in which the angular position of the output shaft can be precisely adjusted to any desired angular position. According to a first aspect of the invention, this object is achieved by the drive unit according to claim 1. According to a second aspect of the invention, this object is also achieved by the robot according to claim 4. According to a third aspect of the invention, this object is also achieved by the method according to claim 5. Advantageous improvements are presented in the dependent claims.

[0006] Acceleration is understood to refer to the acceleration of the drive motor, which is transmitted to the output shaft via the drive shaft and the strain wave gear mechanism. All components involved are accelerated here, and in particular, the flexible ring expands. In the following text, speed is also understood to refer to the individual speeds of all components, wherein the drive shaft and the flexible ring have higher speeds than the output shaft, corresponding to the gear ratio of the strain wave gear mechanism.

[0007] According to a first aspect of the invention, the drive unit is characterized by a third sensor for detecting the expansion of the flexible ring. All variables affecting the position of the output shaft are known by means of the first, second, and third sensors, and an adjustment method based on said all variables can be used, resulting in precise positioning of the output shaft. Such a method can be, for example, an adjustment method in which, in addition to using the output shaft position detected by the second sensor as the actual value, the expansion detected by the third sensor is also directly used as the actual value. Preferably, the adjustment method includes a calibration method connected upstream, and during operation of the drive unit, adjustment is performed using information obtained according to the calibration method to use only the actual angular position of the output shaft as the actual value. Such a method is proposed below according to a second aspect of the invention.

[0008] The third sensor can be, for example, a sensor used to detect the position relative to a fixed component or strain gauge.

[0009] According to a preferred embodiment of the invention, the flexible ring has a radially extending collar, and a third sensor is arranged on the collar. In this way, the third sensor is advantageously positioned away from the area where the flexible ring is operatively connected to the wave generator or engages with the toothed ring. Furthermore, the expansion of the flexible ring can be reliably measured on the collar.

[0010] In another preferred embodiment, the second sensor is arranged on the gear ring. This second sensor is advantageously positioned on the first output-side element of the drive unit, allowing direct detection of the output shaft position during operation. Furthermore, the drive unit can be advantageously used with the second sensor arranged on the gear ring and can have a number of different additional components on the output side.

[0011] In another preferred embodiment, the drive motor, strain wave gear mechanism, and first sensor are arranged coaxially with the drive shaft. This creates a compact drive unit.

[0012] A second aspect of the invention relates to a robot having the drive unit described above. In particular, this robot is a robotic arm for use in industrial, laboratory, or medical applications. This robot therefore possesses the advantages described above.

[0013] A third aspect of the invention relates to a method for adjusting the angular position in a drive unit as described above during positioning by means of a drive motor via a drive shaft and a strain wave gear mechanism.

[0014] According to the present invention, the method includes a calibration method in which, during acceleration, the angular distances of the drive shaft and the output shaft are determined by means of a first, second, and third sensor, with respect to these angular distances, a nonlinear relationship exists between the angular positions of the drive shaft and the output shaft due to the elongation of the flexible ring. Based on the angular distances determined in this way, it is then known that during acceleration, the actual angular position of the output shaft is superimposed or falsified by the expansion of the flexible ring, which cannot be accurately detected; therefore, the angular position can only be inaccurately detected by the second sensor. This information can then be taken into account when positioning the output shaft. Using the second sensor as an actual value generator makes it impossible to precisely control the angular position of the setpoint located within such angular distances from the actual angular position, and such precise control requires a modified adjustment strategy.

[0015] The calibration process is performed only once to detect all significant values. The calibration method is preferably performed on the drive unit, which is in the mounting condition for subsequent positioning of the output shaft, i.e., under operating conditions. The effects of components attached to the drive unit and other environmental conditions are also considered. The calibration method is preferably performed again at regular time intervals and / or after a limited number of positioning processes.

[0016] During the calibration process, the angular distance of the drive shaft and the angular distance of the output shaft are measured simultaneously. The angular distance of the drive shaft is related to the transmission ratio of the strain wave gear mechanism and the expansion of the flexible ring, and is also related to the angular distance of the output shaft.

[0017] This calibration method is preferably performed with a defined acceleration, which is also specifically used below to position the output shaft, because the detected angular distance is specific to such an acceleration. Alternatively, other angular distances can be interpolated or extrapolated for other acceleration curves based on the information obtained.

[0018] Furthermore, according to the invention, the method includes a positioning method for adjusting the angular position of the output shaft from an actual angular position to a target angular position using a second sensor as an actual value generator. This involves checking whether a at least determined angular distance of the output shaft exists between the actual angular position and the target angular position, and if not, rotating the output shaft until the actual angular position and the target angular position are spaced apart by at least a determined angular distance, and then adjusting the actual angular position to the target angular position using the second sensor. In this way, it is ensured that adjustment is not required at any point in time within a set angular position that would be impossible to precisely adjust. Advantageously, continuous detection and processing of the expansion of the flexible ring is not required during adjustment. In the continuous operation of the drive unit, positioning processing is performed for each new target angular position of the output shaft.

[0019] In one implementation, the first sensor is also used as a real value generator, at least as an alternative, in addition to the second sensor. Specifically, the first sensor is used to move the output shaft from a first actual angular position to an actual angular position spaced at least a determined angular distance from the target angular position. In this way, the upstream positioning process is not limited by the requirement that the detected angular distance be greater than the output shaft.

[0020] In a preferred embodiment of the method, the expansion of the flexible ring is first set to 0%, and the angular position of the drive shaft is detected by a first sensor and the angular position of the output shaft is detected by a second sensor as a first angular position. Then, the output shaft is accelerated to a first speed in a defined manner in a first rotational direction, wherein, once a third sensor detects the continued expansion of the flexible ring, the angular position of the drive shaft is detected by the first sensor and the angular position of the output shaft is detected by the second sensor as a second angular position. The distance between the first and second detected angular positions is then defined as a co-directional angular distance. The term "co-directional" refers to a rotation relative to a previous rotation and is understood to mean that the rotation and the previous rotation are in the same direction. The co-directional angular distance is an angular distance within which, if there is a rotation in the same direction prior to the rotation to be adjusted, it is impossible to use the second sensor as a real value generator for precise adjustment.

[0021] In another embodiment of this method, the output shaft is then stopped, and the angular position of the drive shaft is detected by a first sensor and the angular position of the output shaft is detected by a second sensor as a third angular position. The output shaft is then rotated in a second rotational direction, and once the third sensor detects that the expansion of the flexible ring is 0%, the output shaft is stopped again, wherein, in the stationary state, the angular position of the drive shaft is detected by the first sensor and the angular position of the output shaft is detected by the second sensor as a fourth angular position. Then, the output shaft is accelerated in a defined manner in the second direction, wherein, once the third sensor detects that the expansion of the flexible ring is constant, the angular position of the drive shaft is detected by the first sensor and the angular position of the output shaft is detected by the second sensor as a fifth angular position. The distance between the third and fifth detected angular positions is then defined as an opposite angular distance. The term "opposite" refers to a rotation relative to a previous rotation and is understood to mean that the rotation and the previous rotation are in opposite directions. The opposite angular range is the range within which, if there is a rotation in the opposite direction before the rotation to be adjusted, it is impossible to use the second sensor as a real value generator for precise adjustment.

[0022] The angular portions in the same direction and those in opposite directions differ from each other in that, because the spring constant of the flexible ring is typically very low, a sustained expansion occurs in the flexible ring after acceleration, which does not subside when the drive shaft comes to rest again. Therefore, this sustained expansion is called residual expansion. If the flexible ring is first accelerated in the first direction and then in the second direction, the residual expansion from the first rotation must be triggered first once the flexible ring is stretched by the acceleration in the second direction. For this reason, the angular distance in the same direction where residual expansion already exists during acceleration is shorter than the angular distance in the opposite direction where residual expansion from the previous rotation must be triggered first.

[0023] Advantageously, after detecting the same-direction angular distance and opposite-direction angular distance in the positioning method, the same-direction angular distance or opposite-direction angular distance of the output shaft can be used as the basis for checking the distance between the actual angular position and the target angular position, based on the rotation direction during the previous rotation of the output shaft. In this way, the shortest possible angular distance is always used as the basis for the check, thus avoiding unnecessary distances between the actual angular position and the target angular position.

[0024] In another preferred embodiment of the method, the difference between the distance between the third and fourth detected angular positions of the drive shaft normalized by the transmission ratio and the distance between the third and fourth detected angular positions of the output shaft is defined as residual expansion. The residual expansion under acceleration is then advantageously known and can be used to correct the measurements of the second sensor.

[0025] In a preferred embodiment, in the positioning method, the output shaft rotates in the same rotational direction as the immediately preceding rotation to space the actual angular position from the target angular position by at least a determined angular distance. Therefore, further changes in direction are avoided. Specifically, since coarse positioning is sufficient here, the first sensor can be used as an actual value generator to space the actual angular position from the setpoint angular position, and the measurements from the first sensor are not superimposed by any expansion of the flexible ring.

[0026] In another preferred embodiment, in the positioning method, when checking the distance between the actual angular position and the target angular position, the same-direction angular distance or opposite-direction angular distance is used as the basis according to the rotation direction of the previous rotation of the output shaft. As described above, the shortest possible angular distance is always used as the basis for the check, thereby avoiding unnecessary distances between the actual angular position and the set angular position. Attached Figure Description

[0027] Further improvements to the present invention will now be described using the accompanying drawings and a description of preferred exemplary embodiments. In the drawings:

[0028] Figure 1 A schematic cross-section of the drive unit according to the present invention is shown;

[0029] Figure 2 The diagram shows the output shaft angular position on the first y-axis relative to the drive shaft angular position on the x-axis and the expansion of the flexible ring on the second y-axis during acceleration.

[0030] Figure 3 A graph showing the output shaft angular position on the first y-axis relative to the drive shaft angular position on the x-axis and the torque in the flexible ring on the second y-axis during acceleration is shown.

[0031] Figure 4A schematic representation of a positioning method for an output shaft according to the present invention is shown, wherein there is a sufficient distance between the actual angular position and the setting point angular position and they rotate in the same direction;

[0032] Figure 5 A schematic representation of a positioning method for an output shaft according to the present invention is shown, wherein the distance between the actual angular position and the desired angular position is sufficient and they are rotated in opposite directions;

[0033] Figure 6 A schematic representation of a positioning method for an output shaft according to the present invention is shown when the distance between the actual angular position and the desired angular position is insufficient and the rotation is in the same direction;

[0034] Figure 7 A schematic representation of a positioning method for an output shaft according to the present invention is shown when the distance between the actual angular position and the desired angular position is insufficient and the shaft rotates in opposite directions; and

[0035] Figure 8 A significantly simplified representation of a robotic arm with a drive unit according to the present invention is shown. Detailed Implementation

[0036] Figure 1 A drive unit 1 is shown, which has a housing 2 externally defining it. Inside the housing 2, a drive shaft 3 is mounted by means of ball bearings 10a and 10b, which can be driven by a drive motor 4 having a stator 4a and a rotor 4b. Furthermore, a strain wave gear mechanism 5 is arranged on the drive shaft 3, which converts the rotational motion of the drive shaft 3 into a slower rotational output. The strain wave gear mechanism 5 has a high transmission ratio and rigidity. A first sensor 6a is also arranged on the drive shaft 3, and this first sensor detects the angular position of the drive shaft 3. The first sensor 6a is designed as a rotary encoder here. The brake 7 also acts on the drive shaft 3, by means of which the drive shaft 3 can be braked.

[0037] The strain wave gear mechanism 5 includes: a wave generator 5a; a flexible ring 5c ​​mounted opposite to the wave generator 5a by means of a ball bearing 5b; and a gear ring 5d. The wave generator 5a is directly formed on the drive shaft 3, while the gear ring 5d forms the output of the strain wave gear mechanism 5 and is connected to or can be connected to the output shaft 11. A second sensor 6b is arranged on the gear ring 5d, which detects the angular position of the gear ring 5d. This angular position is also the angular position of the output shaft 11. Therefore, the second sensor 6b detects the angular position of the gear ring 5d relative to the corresponding sensor component 6d on the stationary component 8 on the housing side. The flexible ring 5c ​​has a collar 5e by means of which the flexible ring is fixed to the housing 2. A third sensor 6c is arranged on the collar 5e to detect the torsional expansion ω of the flexible ring 5c. For this purpose, the relative displacement of the measuring point on the flexible ring 5c ​​with respect to the fixing member 9 on the housing side is detected.

[0038] Figure 2 and Figure 3 The angular position of drive shaft 3 during acceleration is shown. Angular position of output shaft 11 (or gear ring 5d) The process, and Figure 2 The process of expansion ω of the flexible ring and Figure 3 The process of torque T in the flexible ring 5c. The torque T, or expansion ω, in the flexible ring 5c ​​accumulates during acceleration until the maximum expansion ω. max and maximum torque T max Among them, the angular position of output shaft 11 Still no change or corner position Follow drive shaft 3. If acceleration reaches a constant target speed, the torque T or the resulting expansion ω decreases until the torque or the resulting expansion reaches a continuous value ω. k or T k At this point, at the angular position of drive shaft 3... Angular position relative to output shaft 11 There is a non-linear relationship between them, making it impossible to precisely adjust the positioning of the output shaft 11 using only the value of the second sensor 6b as the actual value generator. From this point onward, the angular position of the drive shaft 3... Angular position relative to output shaft 11 A linear relationship exists between them again. Output shaft 11 is located at an angular position. The position of all angles can be adjusted by using the second sensor 6b as an actual value generator.

[0039] Under the condition of acceleration in the same direction, there exists a point at zero and reaching ω. k or T k angular distance between points Regarding this angular distance, due to the expansion of the flexible ring 5c, at the angular position of the drive shaft... Angular position relative to output shaft 11 There is a nonlinear relationship between them. For output axis 11, there exists a zero point and ω. k or T k angular distance between points Regarding this angular distance, due to the expansion of the flexible ring 5c, there is a nonlinear relationship between the angular position of the drive shaft and the angular position of the output shaft 11.

[0040] In the case of reverse acceleration, the corresponding continuous expansion ω must also be reduced from the previous rotation. k The residual expansion. This then creates the point of drive shaft 3 corresponding to the residual elongation. With reaching ω k angular distance between points Regarding this angular distance, due to the expansion of the flexible ring 5c, at the angular position of the drive shaft 3... Angular position relative to output shaft 11 There is a nonlinear relationship between them. For output axis 11, there exists a point corresponding to the residual expansion. With reaching ω k angular distance between points Regarding this angular distance, due to the expansion of the flexible ring 5c, at the angular position of the drive shaft 3... Angular position relative to output shaft 11 There is a non-linear relationship between them.

[0041] Figures 4 to 7 The diagram shows at least the angular distance depending on the output shaft 11. It is located between the actual angular position and the target angular position. Figure 4 and Figure 5 It is still not located between the actual angular position and the target angular position. Figure 6 and Figure 7 The positioning method of output shaft 11 under different conditions. Furthermore, based on the target angular position being located in the same direction when viewed from the actual angular position ( Figure 4 and Figure 6 ) or in the opposite direction ( Figure 5 and Figure 7 This is used to consider various scenarios. The actual angular position is shown as a dot, while the target angular position is shown as a square.

[0042] According to Figure 4 When the target angular position is corrected to the actual angular position, whether the actual angular position and the target angular position are separated by at least the corrected angular distance of the output shaft 11. An inspection was conducted. Since this was confirmed, output shaft 11 was immediately moved to the target angular position.

[0043] According to Figure 5 If the target angular position and the actual angular position are in opposite directions, determine whether the actual angular position and the target angular position are separated from each other by at least an opposite angular distance of the output shaft 11. An inspection was conducted. Since this was confirmed, output shaft 11 was immediately moved to the target angular position.

[0044] According to Figure 6When the target angular position is corrected to the actual angular position, whether the actual angular position and the target angular position are separated by at least the corrected angular distance of the output shaft 11. An inspection was conducted. Since this was determined not to be the case, the output shaft 11 was first moved in the same direction of rotation to a new actual angular position, which is at least an angular distance opposite to the set point angular position of the output shaft 11. Then, the output shaft 11 is moved to the desired angular position.

[0045] According to Figure 7 If the target angular position and the actual angular position are in opposite directions, determine whether the actual angular position and the target angular position are separated from each other by at least an opposite angular distance of the output shaft 11. An inspection was conducted. Since this was determined not to be the case, the output shaft 11 was first moved in the same direction of rotation to a new actual angular position, which is at least an angular distance opposite to the set point angular position of the output shaft 11. Then, the output shaft 11 is moved to the desired angular position.

[0046] Figure 8 A robot 15 in the form of a robotic arm is shown, having a drive unit 1 for driving the output shaft 11. A first additional shaft 13a and a second additional shaft 13b are connected to the drive unit 1 via a first joint 12a and a second joint 12b. As an example, a gripping tool 14 is arranged on the second additional shaft 13b. Additional drive devices 1 according to the invention can be arranged in the joints 12a, 12b to control the additional shafts 12a, 12b in each case.

[0047] List of reference numerals

[0048] 1. Drive Unit

[0049] 2. Shell

[0050] 3 drive shafts

[0051] 4 drive motors

[0052] 4a stator

[0053] 4a Rotor

[0054] 5. Strain Gauge Mechanism

[0055] 5A wave generator

[0056] 5b ball bearing

[0057] 5c Flexible ring

[0058] 5d toothed ring

[0059] 5e Flexible ring collar

[0060] 6a First Sensor

[0061] 6b Second Sensor

[0062] 6c Third Sensor

[0063] 6D sensor components

[0064] 7. Brakes

[0065] 8. Fixed housing side components

[0066] 9. Fixed housing side components

[0067] 10a ball bearing

[0068] 10b ball bearing

[0069] 11 Output shaft

[0070] 12a First joint

[0071] 12b Second joint

[0072] 13a First additional axis

[0073] 13b Second additional axis

[0074] 14. Gripping tools

[0075] 15 robots

[0076] angular position of drive shaft

[0077] Points corresponding to residual expansion

[0078] angular distance of drive shaft in the same direction

[0079] Opposite angular distance of drive shaft

[0080] angular position of the output shaft

[0081] Points corresponding to residual expansion

[0082] Angular distance of the output shaft in the same direction

[0083] Opposite angular distance of the output shaft

[0084] ω Expansion of the flexible ring

[0085] ωmax Maximum expansion of flexible ring

[0086] ω k Continuous expansion of flexible ring

[0087] Torque in the T-shaped flexible ring

[0088] T max Maximum torque in the flexible ring

[0089] Continuous torque in Tk flexible ring

Claims

1. A drive unit (1) for a robot (15), the drive unit having: a drive shaft (3); a drive motor (4) for driving the drive shaft (3); and a strain wave gear mechanism (5) for transmission from the drive shaft (3) to an output shaft (11), the strain wave gear mechanism (5) having: a wave generator (5a) operably connected to the drive shaft (3); a flexible ring (5c); and a gear ring (5d) capable of being connected to the output shaft (11), the drive unit comprising: The first sensor (6a) is used to detect the angular position of the drive shaft (3). ); and a second sensor (6b) for detecting the angular position of the output shaft (11) The feature is that a third sensor (6c) is used to detect the expansion of the flexible ring (5c). The first sensor (6a), the second sensor (6b), and the third sensor (6c) are configured to determine the angular distance between the drive shaft (3) and the output shaft (11) during acceleration using the first sensor (6a), the second sensor (6b), and the third sensor (6c). , , , Regarding the angular distance, due to the expansion of the flexible ring (5c) ) and at the angular position of the drive shaft (3) The angular position of the output shaft (11) and the output shaft (11) There is a non-linear relationship between them.

2. The driving unit (1) according to claim 1. Its features are, The flexible ring (5c) has a radially extending collar (5e), ​​and the third sensor (6c) is arranged on the collar (5e).

3. The drive unit (1) according to claim 1 or 2. Its features are, The second sensor (6b) is arranged on the toothed ring (5d).

4. A robot (15) having at least one drive unit (1) according to any one of the preceding claims.

5. A method for adjusting the angular position of the output shaft (11) in a drive unit (1) according to any one of claims 1 to 3 when it is positioned by means of the drive motor (4) via the drive shaft (3) and the strain wave gear mechanism (5). The method includes: - A calibration method in which the angular distance between the drive shaft (3) and the output shaft (11) is determined during acceleration using a first sensor, a second sensor, and a third sensor (6a, 6b, 6c). , , , Regarding the angular distance, due to the expansion of the flexible ring (5c) ) and at the angular position of the drive shaft (3) The angular position of the output shaft (11) and the output shaft (11) There is a non-linear relationship between them. - A positioning method for using the second sensor (6b) as an actual value generator to determine the angular position of the output shaft (11). Adjust from the actual angular position to the target angular position, and determine whether there exists at least a determined angular distance between the actual angular position and the target angular position of the output shaft (11). , If the actual angular position is not the target angular position, the output shaft (11) is rotated until the actual angular position is spaced apart from the target angular position by at least the determined angular distance of the output shaft (11). , The actual angular position is then adjusted to the target angular position using the second sensor (6b).

6. The method according to claim 5, Its features are, During the calibration process, - First, the expansion of the flexible ring (5c) The value is set to 0%, and the angular position of the drive shaft (3) is detected by means of the first sensor (6a). And the angular position of the output shaft (11) is detected by the second sensor (6b). ) as the first corner position ( , ), -Then, the output shaft (11) is accelerated to a first speed in a defined manner in the first rotational direction, wherein, once the third sensor (6c) detects the continuous expansion (ω) of the flexible ring (5c), the angular position of the drive shaft (3) is detected by means of the first sensor (6a). And the angular position of the output shaft (11) is detected by the second sensor (6b). ) as the second corner position ( , ), - The first detected angular position ( , ) and the angular position of the second detection ( , The distance between them is limited to the angular distance in the same direction. , ).

7. The method according to claim 6, Its features are, Subsequently, - Stop the output shaft (11), and detect the third corner position by means of the first sensor (6a). , ) and the angular position of the drive shaft (3) And the angular position of the output shaft (11) is detected by means of the second sensor (6b). ), -Then, the output shaft (11) is rotated in the second rotational direction, and once the third sensor (6c) detects the expansion of the flexible ring (5c) When the value is 0%, the output shaft is stopped again, wherein, in the stationary state, the angular position of the drive shaft (3) is detected by means of the first sensor (6a). And the angular position of the output shaft (11) is detected by means of the second sensor (6b). ) as the fourth corner position ( , ) -Then, the output shaft (11) is accelerated in a defined manner in the second direction, wherein, once the third sensor (6c) detects the expansion of the flexible ring (5c) If the angular position of the drive shaft (3) remains unchanged, it is detected by means of the first sensor (6a). And the angular position of the output shaft (11) is detected by means of the second sensor (6b). ) as the fifth corner position ( , ), - The corner position of the third detection ( , ) and the angular position of the fifth detection ( , The distance between them can be defined as the opposite angular distance. , ).

8. The method according to claim 7, Its features are, Residual expansion ( ) is the angular position of the third detection of the drive shaft (3). ) and the angular position of the fourth detection ( The distance between the two is the same as the angular position of the third detection of the output shaft (11). ) and the angular position of the fourth detection ( The difference between the distances between them.

9. The method according to any one of claims 5 to 8, Its features are, In the positioning process, the output shaft (11) rotates in the same rotational direction as the immediately preceding rotation to space the actual angular position from the target angular position by at least the determined angular distance. , ).

10. The method according to claim 7 or 8, Its features are, In the positioning method, when checking the distance between the actual angular position and the target angular position, the same-direction angular distance or the opposite angular distance is determined according to the rotation direction of the previous rotation of the output shaft (11). , ) is used as a basis.

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