CHANGE DEVICE FOR CHANGING OF TOOLS AND/OR WORKPIECES

Abstract

A change device for changing or exchanging of tools and/or workpieces. The change device has a gripper device with at least one gripper arm that extends away from a rotation support body that is rotatably supported about the rotation axis and that has a holder for respectively one tool or one workpiece at its free end. By means of a rotary power train with a rotary drive motor and a rotary drive transmission, the gripper device can be rotated about the rotation axis. Particularly the rotary drive transmission has a belt gear. A first rotary position sensor is directly or indirectly coupled with the rotation support body and/or transmission output of the rotary drive transmission without interconnection of the rotary drive transmission for detection of the rotary position of the gripper device about the rotation axis.

Claims

1. A change device that is configured for changing tools and/or workpieces, comprising: a gripper device that is rotatably supported about a rotation axis at a rotation support body, the gripper device having at least one holder for a tool and/or a workpiece to be held, a rotary power train that is configured to rotate the gripper device about the rotation axis, wherein the rotary power train comprises a rotary drive motor and a rotary drive transmission, wherein the rotary drive motor is drivingly coupled with a transmission input of the rotary drive transmission and wherein transmission output of the rotary drive transmission is drivingly connected with the rotation support body, a first rotary position sensor that is coupled with the rotation support body without interconnection of the rotary drive transmission, wherein the first rotary position sensor is configured to detect a rotary position of the gripper device about the rotation axis.

2. The change device according to claim 1, wherein the rotary drive transmission comprises a first belt gear.

3. The change device according to claim 1, wherein the first rotary position sensor is coupled with the rotation support body in a torque-proof manner.

4. The change device according to claim 1, wherein the first rotary position sensor is coupled with the rotation support body via at least one coupling element in a non-torque-proof manner.

5. The change device according to claim 4, wherein the coupling element is a coupling belt.

6. The change device according to claim 1, wherein a control device is provided and a sensor signal of the first rotary position sensor is submitted to the control device and control device is configured to control the rotary drive motor.

7. The change device according to claim 6, wherein the rotary power train comprises an additional sensor that is configured to create a sensor signal corresponding to a rotary position of the transmission input and wherein the sensor signal of the additional sensor is submitted to the control device.

8. The change device according to claim 7, wherein the additional sensor is a motor sensor that is configured to detect a rotary position of the rotary drive motor about a motor axis of the rotary drive motor and the motor sensor submits a sensor signal corresponding to the rotary position of the rotary drive motor to the control device.

9. The change device according to claim 7, wherein the control device is configured to determine a mass of the tool or workpiece that is held in the at least one holder.

10. The change device according to claim 7, wherein the rotary drive transmission comprises a first belt gear and the control device is configured to determine a rupture of a belt of the first belt gear.

11. The change device according to claim 1, further comprising: a shift power train configured to move the gripper device along the rotation axis.

12. The change device according to claim 11, wherein the shift power train comprises a shift drive transmission having a transmission input and a transmission output, a shift drive motor drivingly coupled with the transmission input and a threaded spindle having a spindle nut, wherein the threaded spindle is drivingly coupled with the transmission output of the shift drive transmission.

13. The change device according to claim 12, wherein a control device is provided and a sensor signal of the first rotary position sensor is submitted to the control device and the control device is configured to control the rotary drive motor and a second rotary position sensor, the second rotary position sensor being coupled with the threaded spindle without interconnection of the shift drive transmission , the second rotary position sensor creates a sensor signal for determining rotation movement and/or rotary position of the threaded spindle about the rotation axis and the second rotary position sensor submits the sensor signal to the control device.

14. The change device according to claim 12, wherein a control device is provided and a sensor signal of the first rotary position sensor is submitted to the control device and the control device is configured to control the rotary drive motor and wherein the shift power train comprises a motor sensor that is creates a sensor signal for determining a rotary position of the transmission input of the shift drive transmission and the motor sensor submits the sensor signal to the control device.

15. The change device according to claim 12, wherein the shift drive transmission comprises a second belt gear.

16. The change device according to claim 15, wherein the control device is configured to determine a rupture of a belt of the second belt gear.

17. The change device according to claim 12, wherein the spindle nut is immovably connected with the rotation support body or is an integral part of the rotation support body.

18. The change device according to claim 12, wherein the spindle nut is supported in a torque-proof manner relative to the transmission output of the rotary drive transmission.

19. The change device according to claim 1, wherein the rotary drive transmission comprises a transmission housing in which the first rotary position sensor is arranged.

20. The change device according to claim 19, wherein the rotary drive transmission comprises a transmission housing in which the first rotary position sensor is arranged and the second rotary position sensor is arranged in the transmission housing.

21. The change device according to claim 1, wherein the gripper device comprises at least one gripper arm extending away from the rotation support body orthogonal to the rotation axis, wherein the gripper arm has at its free end opposite the rotation support body a holder for the tool and/or the workpiece.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0025] In the following preferred embodiments of the invention are explained in detail with reference to the attached drawings. The drawings show:

[0026] FIG. 1 a perspective view of an embodiment of a change device,

[0027] FIG. 2 a schematic block-diagram-like illustration of an embodiment of a change device,

[0028] FIG. 3 a schematic block-diagram-like illustration of an embodiment of a change device,

[0029] FIG. 4 a schematic block-diagram-like illustration of an embodiment of a rotary position sensor and

[0030] FIGS. 5-8 each are a schematic illustration of a spindle of a machine tool and a change device in different states during execution of a tool change.

DETAILED DESCRIPTION

[0031] FIG. 1 shows a change device 15 according to the invention that is configured to automatically change or exchange a tool 16 (FIGS. 5-8). In the embodiment the change device 15 is configured to insert or remove different tools 16 in or from a spindle holding fixture 17 of a machine spindle 18 of a machine tool. A tool 16 to be inserted can be removed from a storing location 19 of a non-illustrated tool magazine, for example, and can be inserted into the spindle holding fixture 17 of the machine spindle 18. The progress will be described subsequently based on FIGS. 5-8.

[0032] In the described embodiment the change device 15 is configured for automatic change of tools 16. Alternatively or additionally, the change device 15 can also be configured for change of workpieces.

[0033] In the embodiment the change device 15 has a gripper device 20 with at least one and according to the example, precisely two holders 21, each configured for holding or gripping one tool 16. By means of the gripper device 20, one tool 16 or two tools 16 can be gripped or held.

[0034] The gripper device 20 is arranged at a rotation support body 22 that is rotationally supported about a rotation axis D. The gripper device 20 can thus be rotated together with the rotation support body 22 about the rotation axis D. For executing the rotation movement of the gripper device 20 a rotary power train 23 is provided. Embodiments for the support of gripper device 20 and the configuration of the rotary power train 23 are illustrated in the block-diagram-like illustrations of FIGS. 2 and 3.

[0035] In the embodiment the gripper device 20 is configured as double gripper. It comprises two gripper arms 24 that extend originating from the rotation support body 22 in opposite directions. Each gripper arm 24 has a radial outer free end opposite the rotation axis D at which a holder 21 for one tool 16 is provided. In the embodiment the gripper arms 24 extend along a common straight line that is orientated orthogonal to the rotation axis D or radial to the rotation axis D. In a modification to the embodiment the number of gripper arms 24 or the number of holders 21 can be larger or lower.

[0036] The rotary power train 23 has a rotary drive transmission 28 with transmission input 28a and a transmission output 28b. In the embodiment the transmission output 28b of the rotary drive transmission 28 is connected in a torque-proof manner with the rotation support body 22. The transmission input 28a of the rotary drive transmission 28 is connected in a torque-proof manner with a first drive shaft 29 that is driven from a rotary drive motor 30 of the rotary power train 23. Thus, the rotary power train 23 establishes a driving connection between the rotary drive motor 30 and the rotation support body 22 via the rotary drive transmission 28.

[0037] In the embodiment the rotary drive transmission 28 comprises a first belt gear 33 and is formed by the first belt gear 33 in the embodiment. A first drive pulley 34 is connected in a torque-proof manner with the first drive shaft 29 and forms the transmission input 28a of the rotary drive transmission 28. A first output pulley 35 is connected in a torque-proof manner with the rotation support body 22 and forms the transmission output 28b of the rotary drive transmission 28. A first belt 36 connects the first drive pulley 34 with the first output pulley 35 in a torque-proof manner. The first belt 36 is configured as tooth belt and accordingly the first drive pulley 34 and the first output pulley 35 are configured as tooth belt discs.

[0038] The first belt gear 33 can provide an arbitrary ratio that can be smaller than 1, larger than 1 or equal to 1.

[0039] The rotary drive transmission 28 is arranged in a transmission housing 37. The first drive shaft 29 and the rotation support body 22 extend from the transmission housing 37. The first drive shaft 29 extends along a first motor axis M1 and can be rotationally driven about the first motor axis M1 by means of the rotary drive motor 30. In the embodiment the first motor axis M1 extends with distance to the rotation axis D. Preferably the first motor axis M1 is arranged vertically above the rotation axis D in the assembled condition of the change device 15.

[0040] The actual rotary position of the gripper device 20 or the gripper arms 24 about the rotation axis D is detected by a first rotary position sensor 40 that is configured to create a first sensor signal S1 characterizing the actual rotary position of the gripper device 20 or the gripper arms 24 about the rotation axis D and to submit the first sensor signal S1 to a control device 41. The control device 41 can create a first control signal A1 for control of the rotary drive motor 30 based at least on the first sensor signal S1 of the first rotary position sensor 40.

[0041] The first rotary position sensor 40 is coupled with the transmission output 28b and the rotation support body 22 without interconnection of the rotary drive transmission 28 and at least without interconnection of the belt gear 33. In doing so, the actual rotary position of the gripper device 20 about the rotation axis D can be detected and thus controlled by the control device 41 very precisely. The first rotary position sensor 40 can be coupled with the transmission output 28b of the rotary drive transmission 28 and the rotation support body 22 for detection of the rotary position of the gripper device 20 in a torque-proof manner or indirectly.

[0042] The first rotary position sensor 40 is arranged in the transmission housing 37 and thus protected from external influences, e.g. from interferences due to cooling media and/or chips in the machine tool.

[0043] The configuration of a rotary position sensor that can be used as first rotary position sensor 40 is highly schematically illustrated in FIG. 4. The rotary position sensor comprises a non-rotating stationary sensor part 42, as well as a rotatable sensor part 43 that is rotatably supported relative to the stationary sensor part 42. The rotatable sensor part 43 is rotatingly movably coupled with the rotation support body 22. The rotatable sensor part 43 can be connected with the rotation support body 22 in a torque-proof manner and can rotate together with the rotation support body 22, as schematically illustrated in FIG. 3. Alternatively the rotatable sensor part 43 can be indirectly coupled with the rotation support body 22 via one or more coupling elements. In the embodiment shown in FIG. 2 the coupling between the rotatable sensor part 43 and the rotation support body 22 or the transmission output 28b can be realized via a first coupling gear 44. The first coupling gear 44 has a first coupling pulley 45 coupled with the rotation support body 22 and the transmission output 28b in a torque-proof manner and a second coupling pulley 46 coupled with the rotatable sensor part 43 in a torque-proof manner. The two coupling pulleys 45, 46 are rotationally movably coupled via a coupling belt 47. The coupling belt 47 is preferably configured as tooth belt.

[0044] Independent from the load to which the rotary power train 23 is subjected, the coupling of the first rotary position sensor 40 with the transmission output 28b and/or the rotation support body 22 is substantially load free. In doing so, the actual rotary position of the gripper device 20 about the rotation axis D can be detected very precisely.

[0045] As illustrated in FIGS. 2 and 3, the rotary power train 23 comprises an additional sensor 50. The additional sensor 50 is configured to create a sensor signal characterizing the rotary position or rotation movement of the first drive shaft 29 or the transmission input 28a of the rotary drive transmission 28 that is referenced here as second sensor signal S2. The second sensor signal S2 is submitted to the control device 41. According to the example, the additional sensor 50 is formed by a first motor sensor 51 that detects the rotary position of the rotary drive motor 30 about the first motor axis M1.

[0046] Thus, two separate sensor signals S1, S2 are provided to the control device 41 that depend from each other at least in the failure-free normal operation. In the normal operation during a rotation of the first drive shaft 29 about the first motor axis M1 the gripper device 20 rotates about the rotation axis D.

[0047] In a rotary power train with ideal configuration and without play and elasticities the second sensor signal S2 also characterizes the actual rotary position of the gripper device 20 about the rotation axis D. The two sensor signals 51, S2 have a defined fixed relation or dependency. In a real rotary power train 23 the rotary drive transmission 28 comprises play and/or elasticities. Particularly in the configuration according to the example with the first belt gear 33, a relation between the first sensor signal S1 and the second sensor signal S2 can vary with reference to the progression in time and/or with reference to the amount depending on the actual operating condition of the change device 15 or the rotary power train 23. This is particularly caused by the weight force of the one or the two tools 16 held by the gripper device 20, the weight force or weight forces of which cause a torque about the rotation axis D. This torque depends on the position of the gripper arms 24 relative to the horizontal or vertical and also from the weight of the one held tool 16 or from the weight difference of the two held tools 16. Dependent from this torque about the rotation axis D and the torque at the rotary drive motor 30, dynamic elasticities in the rotary drive transmission 28 are created that can have different amounts depending on the operating condition. Thus, the second sensor signal S2 does not necessarily correspond to the actual rotary position of the gripper device 20 about the rotation axis D. For this reason the first rotary position sensor 40 is coupled with the rotation support body 22 independent from the rotary drive transmission 28.

[0048] Because the control device 41 is provided with the first sensor signal S1 as well as the second sensor signal S2, the relation between the two sensor signals S1, S2 can be evaluated for providing additional information. For example, a rupture of the first belt 36 can be determined, because in this case the first sensor signal S1 does not change anymore depending on the rotation of the rotary drive motor 30. The actual rotary position of the gripper device 20 can no longer be influenced by the rotary drive motor 30. For example, the gripper device 20 can freely move about the rotation axis D in case of a rupture of the first belt 36 until it takes a balanced positionat least if no self-locking effect impedes the free movement.

[0049] The first sensor signal S1 and the second sensor signal S2 can be used additionally or alternatively also to determine the weight or the weight difference of a tool 16 or two tools 16 held in the gripper device 20. For example, the gripper device 20 can be moved in a defined rotary position about the rotation axis D that is defined by the second sensor signal S2. The elasticity in the rotary power train 23 is responsible that the actual rotary position characterized by the first sensor signal S1 does not necessarily correspond to the defined desired rotary position characterized by the second sensor signal S2. The larger the deviation, the larger the weight of a tool held in the gripper device 20. If two tools 16 are held in the gripper device 20, the weight difference can be determined. Preferably, the gripper device 20 is orientated horizontally for determination of the weight, i.e. the gripper arms 24 extend parallel to a horizontal plane. In order to calibrate the weight determination by the control device 41, one or more tools 16 or other bodies can be arranged in the gripper device 20 one time. In doing so, function, a characteristic curve or a characteristic map can be determined and stored such that subsequently a weight determination is possible also for other tools 16.

[0050] If the weight of a tool 16 or weights of tools 16 are known that are stored in a tool magazine of the machine tool, the weights can be considered by the control device 41 for the control of the rotary drive motor 30. Because in this case also the resulting torque and inertia moment about the rotation axis D resulting therefrom are known. The torque of the rotary drive motor 30 can be controlled according to a time-dependent progress in order to achieve a positioning and feedback control of the rotary position of the gripper device 20 about the rotation axis D as quick as possible. In doing so, a required duration for a tool change in a machine tool can be minimized. In addition, vibrations and oscillations of the rotation movement of the gripper device 20 about the rotation axis D can be avoided or minimized.

[0051] In the embodiment the change device 15 also comprises a shift power train 55. The shift power train 55 is configured to move the gripper device 20 along or parallel to the rotation axis D and thus to initiate a shift movement. In the embodiment the shift power train 55 comprises a shift drive transmission 56 having a transmission input 56a and a transmission output 56b. The transmission input 56a of the shift drive transmission 56 is connected with a second drive shaft 57 in a torque-proof manner. The second drive shaft 57 can be driven by a shift drive motor 58. The transmission output 56b of the shift drive transmission 56 is connected with a threaded spindle 59 in a torque-proof manner along which a spindle nut 60 is shiftably supported. For this the spindle nut 60 is locked against a rotation movement about the rotation axis D. The threaded spindle 59 extends along the rotation axis D. The spindle nut 60 is immovably connected with the rotation support body 22 and can thus neither rotate relative to the rotation support body 22, nor move along the rotation axis D relative to the rotation support body 22. The spindle nut 60 can be part of the rotation support body 22 that can be configured as a single part or as an assembly of multiple parts.

[0052] The shift drive transmission 56 comprises a belt gear that is referenced as second belt gear 61 in order to distinguish from the first belt gear 33 of the rotary drive transmission 28. Preferably the shift drive transmission 56 is formed by the second belt gear 61. The second belt gear 61 has a second drive pulley 62 that forms the transmission input 56a and a second output pulley 63 that forms the transmission output 56b. The second drive pulley 62 and the second output pulley 63 are rotationally movably coupled by a second belt 64. The second belt 64 is preferably configured as tooth belt.

[0053] The second drive shaft 57 can be rotationally driven about the second motor axis M2 by the shift drive motor 58. The second motor axis M2 is preferably parallel to the rotation axis D and/or the first motor axis M1 and further preferably arranged vertically above the rotation axis D. The second motor axis M2 can be arranged vertically above the first motor axis M1. The control device 41 is configured to create a second control signal A2 for control of the shift drive motor 58. In the embodiment a second motor sensor 65 is provided analog to the rotary power train 23, wherein the second motor sensor 65 creates a third sensor signal S3 that characterizes the rotary position of the second drive shaft 57 or the transmission input 56a of the shift drive transmission 56 and submits the third sensor signal S3 to the control device 41. The third sensor signal S3 is characteristic for the shift position of the gripper device 20 along the rotation axis D. Because load-dependent deviations due to an elasticity of the shift drive transmission 56 are not relevant or do not have a decisive impact, the position of the gripper device 20 along the rotation axis D can be determined at the transmission input 56a of the shift drive transmission 56.

[0054] In order to allow the shift movement of the gripper device 20 along the rotation axis D, the rotation support body 22 including the spindle nut 60 is connected with the first output pulley 35 or the transmission output 28b of the rotary drive transmission 28 in a torque-proof manner and can be shifted parallel to the rotation axis D. Due to a rotation of the threaded spindle 59, a shift movement can be caused.

[0055] The shift power train 55 further comprises a second rotary position sensor 66 that is assigned to the transmission output 56b of the shift drive transmission 56 and is coupled therewith. The second rotary position sensor 66 creates a fourth sensor signal S4 that is characteristic for the rotary position or the rotation movement at the transmission output 56b of the shift drive transmission 56 and according to the example, for the rotation movement of the threaded spindle 59 and/or the second output pulley 63 about the rotation axis D.

[0056] Thus, also for the shift drive transmission 56 or the shift power train 55 a third sensor signal S3 characterizing the rotation movement at the transmission input 56a and a fourth sensor signal S4 characterizing the rotation movement at the transmission output 56b are provided to the control device 41. Thus, the control device 41 is able to determine deviations, due to failures in the shift drive transmission 56. For example, a belt rupture of the second belt 64 in the second belt gear 61 can be determined.

[0057] The second rotary position sensor 66 can have the configuration shown in FIG. 4 analog to the first rotary position sensor 40.

[0058] In the embodiment shown in FIG. 2 the second rotary position sensor 66 is coupled with the threaded spindle 59 in a manner similar to the coupling of the first rotary position sensor 40 with the rotation support body 22. Specifically a second coupling gear 67 is provided for this with a third coupling pulley 68 that is coupled with the rotatable sensor part 43 of the second rotary position sensor 66 in a torque-proof manner. A fourth coupling pulley 69 is connected with the threaded spindle 59 in a torque-proof manner. The third and fourth coupling pulleys 68, 69 are movably coupled by a second coupling belt 70 of the second coupling gear 67. The second coupling belt 70 is preferably configured as tooth belt.

[0059] Alternatively to this coupling of the second rotary position sensor 66 with the threaded spindle 59, the second rotary position sensor 66 can also be arranged on the level of the rotation axis D. The rotatable sensor part 43 of the second rotary position sensor 66 can then be connected with the threaded spindle 59 or the transmission output 56b of the shift drive transmission 56 indirectly or directly in a torque-proof manner (FIG. 3).

[0060] The embodiments shown in FIGS. 2 and 3 can be combined with each other. For example, one of the rotary position sensors 40, 66 can be coupled via the respective coupling gear 44 or 67 respectively and the respective other rotary position sensor 66 or 40 can be arranged on the level of the rotation axis D and can be torque-proof connected with the rotation support body 22 or the threaded spindle 59 respectively.

[0061] The shift drive transmission 56 is arranged in the transmission housing 37. The transmission housing 37 is thus configured as common transmission housing for the rotary drive transmission 28 and the shift drive transmission 56.

[0062] It has to be noted that the shift movement of the gripper device 20 along or parallel to the rotation axis D and the rotation movement of the gripper device 20 about the rotation axis D can also be effected by other mechanical means.

[0063] The change device 15 described so far can execute an automatic tool change as subsequently described with reference to FIGS. 5-10.

[0064] In FIG. 5 an initial situation is schematically illustrated, wherein a tool 16 is present in the spindle holding fixture 17 that shall be exchanged by another tool 16 that is arranged in the storing location 19 of a tool magazine that is not shown. The change device 15 is positioned between the storing location 19 and the spindle holding fixture 17, such that the gripper device 20 is able to grip the tool 16 provided in the spindle holding fixture 17, as well as the tool 16 provided at the storing location 19 by means of a rotation movement about the rotation axis D (FIG. 5). Subsequently by a shift movement of the gripper device 20 along the rotation axis D the tool 16 is removed from the spindle holding fixture 17 and the tool 16 to be inserted is removed from the storing location 19. The situation resulting therefrom is illustrated in FIG. 6.

[0065] The tools 16 held by the gripper device 20 are released and the gripper device 20 can rotate about the rotation axis D. Subsequently, the tool 16 to be inserted is located in front of the spindle holding fixture 17 and the removed tool 16 is located in front of the storing location 19. Then by a shift movement of the gripper device 20 along the rotation axis D the removed tool 16 can be arranged at the storing location 19 and the tool 16 to be inserted can be arranged in the spindle holding fixture 17 (FIG. 7).

[0066] After this tool exchange the tools 16 are released by the gripper device 20 and the gripper device 20 can rotate about the rotation axis D, e.g. by an amount of about 90 (FIG. 8). Subsequently the change device 15 and/or the tool magazine or the storing location 19 can be moved away such that the working space of the machine tool is ready for machining of a workpiece.

[0067] The invention refers to a change device 15 for changing or exchanging of tools 16 and/or workpieces. The change device 15 has a gripper device 20 with at least one gripper arm 24 that extends away from a rotation support body 22 that is rotatably supported about the rotation axis D and that has a holder 21 for respectively one tool 16 or one workpiece at its free end. By means of a rotary power train 23 with a rotary drive motor 30 and a rotary drive transmission 28, the gripper device 20 can be rotated about the rotation axis D. Particularly the rotary drive transmission 28 has a belt gear 33. A first rotary position sensor 40 is directly or indirectly coupled with the rotation support body 22 and/or transmission output 28b of the rotary drive transmission 28 without interconnection of the rotary drive transmission 28 for detection of the rotary position of the gripper device 20 about the rotation axis D.

LIST OF REFERENCE SIGNS

[0068] 15 change device [0069] 16 Tool [0070] 17 spindle holding fixture [0071] 18 machine spindle [0072] 19 storing location [0073] 20 gripper device [0074] 21 Holder [0075] 22 rotation support body [0076] 23 rotary power train [0077] 24 gripper arm [0078] 28 rotary drive transmission [0079] 28a transmission input of the rotary drive transmission [0080] 28b transmission output of the rotary drive transmission [0081] 29 first drive shaft [0082] 30 rotary drive motor [0083] 33 first belt gear [0084] 34 first drive pulley [0085] 35 first output pulley [0086] 36 first belt [0087] 37 transmission housing [0088] 40 first rotary position sensor [0089] 41 control device [0090] 42 stationary sensor part [0091] 43 rotatable sensor part [0092] 44 coupling gear [0093] 45 first coupling pulley [0094] 46 second coupling pulley [0095] 47 first coupling belt [0096] 50 additional sensor [0097] 51 first motor sensor [0098] 55 shift power train [0099] 56 shift drive transmission [0100] 56a transmission input of the shift drive transmission [0101] 56b transmission output of the shift drive transmission [0102] 57 second drive shaft [0103] 58 shift drive motor [0104] 59 threaded spindle [0105] 60 spindle nut [0106] 61 second belt gear [0107] 62 second drive pulley [0108] 63 second output pulley [0109] 64 second belt [0110] 65 second motor sensor [0111] 66 second rotary position sensor [0112] 67 second coupling gear [0113] 68 third coupling pulley [0114] 69 forth coupling pulley [0115] 70 second coupling belt [0116] A1 first control signal [0117] A2 second control signal [0118] D rotation axis [0119] M1 first motor axis [0120] M2 second motor axis [0121] S1 first sensor signal [0122] S2 second sensor signal [0123] S3 third sensor signal [0124] S4 fourth sensor signal