Gripping or gripping device for gripping or gripping articles in different operating modes and method therefor

Abstract

A gripping or gripping device (10) and an associated method (200) for gripping or gripping an article, the gripping or gripping device (10) comprising: at least one and preferably two main jaws (14, 16) movable towards and away from each other; a driver (22) for driving the at least one main clamping jaw (14, 16); a control unit (20) comprising: a controller (72) for generating a control signal (80, 82, 84) for actuating the driver (22); a memory (74) in which commands and characteristic variables (75) are stored; and a communication interface (70) for receiving predefinable gripping parameters (78), in which the control unit (20) is configured such that: commands for operating at least two different operating modes of the gripping or gripping device (10) are stored in the memory (74), which commands, when processed by the controller (72), are stored in the memory (74); causing the controller (72) to generate a control signal (80, 82, 84) for a corresponding mode of operation; wherein the operating mode corresponding to the selection of the generation of the control signal (80, 82, 84) takes place as a function of at least one predefinable grip parameter (78) and at least one characteristic variable (75) stored in the memory (74).

Description

[0001] The present invention relates to a gripping or clamping device for gripping or clamping an article, the gripping or clamping device having at least one, and preferably two, main jaws that can move towards and away from each other, and the present invention relates to a method for operating such a gripping or clamping device.

[0002] A gripping or clamping device is known from DE10 013 022 A1, in which two main jaws are provided that can move towards and away from each other, and the main jaws are kinematically coupled to a working piston via a gearbox (i.e., a keyway gearbox) and a piston rod. The working piston delimits two piston chambers; depending on the pressure on one or the other piston chamber, the main jaws move towards or away from each other.

[0003] EP 1 905 549 A1 discloses a gripping device having a rotary drive and two sliders synchronized by a synchronizing gear, with shaped teeth for engaging with the synchronizing gear provided on each slider.

[0004] A gripping or clamping device is known from EP 3 359 351 B1, the gripping or clamping device having a drive for driving at least one main jaw and a control unit, the control unit including a controller for generating control signals for actuating the drive, a memory in which commands and characteristic variables are stored, and a communication interface for receiving predefined gripping parameters.

[0005] The object to be achieved by the present invention is to provide a gripping or clamping device that can be used in a variety of ways.

[0006] This object is achieved by a gripping or clamping device for gripping and clamping an article according to claim 1. It is conceivable that the drive is designed as an electric drive having an electric motor, a motor controller, and a gearbox or as a pneumatic drive. Preferably, the gripping or clamping device includes a housing in which the control unit is arranged. It is conceivable that the drive is also arranged in the housing. It is also conceivable that the characteristic variables are obtained from a characteristic map, or that configuration data is stored in the memory and / or parameterized during the production of the gripper or the control unit. Preferably, the communication interface can also send data.

[0007] The control unit is configured such that commands for at least two different operating modes for operating the gripping or clamping device are stored in the memory, and when processed by the controller, the commands cause the controller to generate control signals for the corresponding operating modes, wherein the operating mode corresponding to the generated control signal is selected based on at least one predefined gripping parameter and at least one characteristic variable stored in the memory.

[0008] This has the following advantages: The way the grasping or clamping device grasps or clamps an article does not directly depend on many parameters, but is determined by the control unit based on the transmitted grasping parameters. This will allow, for example, the same grasping or clamping device to be used for different grasping tasks, or for the grasping or clamping device to perform different grasping tasks one after another without having to convert the gripper. Another advantage is that the grasping parameters can be reduced to minimal data, and thereby reduce the load on the communication interface and / or communication network in the machine in which the grasping or clamping device is used, and thus simplify the entire machine. In addition, the implementation of the grasping or clamping device according to the present invention is also simplified because the complexity of the grasping parameters to be transmitted can be significantly reduced. The characteristic variables stored in the memory can also be used by the control unit to check whether the grasping or clamping device can perform a grasping or clamping process based on predefined grasping parameters, which results in the protection of the grasping or clamping device and the article to be grasped.

[0009] The control unit can be configured such that the controller first selects an operating mode based on the grasping parameters in a first stage, and in a second stage checks whether the grasping or clamping device can perform such a grasping process based on the characteristic variables stored in the memory. If necessary, data about the grasping process is then sent via the communication interface.

[0010] It is conceivable that the predefined grasping parameter represents a target grasping force. This means that the grasping or clamping device can grasp a wide variety of different articles and has a wide range of uses. By specifying the target grasping force, the grasping force can be specifically adjusted for the article to be grasped, and thus an adapted grasping can be achieved without damaging or losing the article.

[0011] In addition, it is conceivable that the predefined grasping parameter represents an absolute target grasping force or a relative target grasping force. The relative target grasping force is particularly predefined as a value between 0% and 150% of the normal grasping force. The normal grasping force refers to the force representing 100% of the grasping force of the grasping or clamping device. The relative target grasping force has the advantage that in a machine controller communicating with the control unit via the communication interface, the data to be exchanged is simplified, and thus it is easier for the operator to configure the gripper.

[0012] Advantageously, the control unit is further configured such that a gripping speed corresponding to the respective main gripper is calculated based on predefined gripping parameters. Furthermore, advantageously, a corresponding control signal is generated such that when the main gripper or the gripping finger arranged on the main gripper impacts the workpiece, the impulse is reduced compared to a gripping process with a static gripping speed. Thus, the gripping or clamping device according to the invention can also be used to grip sensitive and less sensitive articles without different grippers or without having to switch grippers between different gripping processes in order to implement different operating modes.

[0013] It is conceivable that the control unit is further configured such that commands for a first operating mode, a second operating mode and / or a third operating mode are stored in the memory. With the first operating mode, a control signal for gripping with a gripping force less than or equal to the normal gripping force is generated. With the second operating mode, a control signal for gripping with a gripping force greater than the normal gripping force is generated. With the third operating mode, a control signal for gripping with a reduced impulse is generated. By providing different operating modes, different articles can be advantageously gripped or clamped. If the predefined gripping speed is lower than the calculated gripping speed, the third operating mode includes, in addition to the predefined gripping force, a predefined gripping speed as a predefined gripping parameter. By gripping more slowly, the kinetic energy in the moving parts of the gripper is reduced and thus also the impulse when the jaws impact the article. This is particularly advantageous for hard and brittle and / or fragile articles that can be used, in particular, in the manufacture of electronic devices.

[0014] It is conceivable that the gripping or clamping device has a braking unit for fixing the at least one main gripper against an elastically flexible preloading device, wherein one of the characteristic variables stored in the memory indicates the presence of the braking unit. It is conceivable that the preloading device is made of at least partially elastically flexible material (such as an elastomer block or a spring element). Furthermore, it can be provided that the control unit is further configured such that commands for an operating mode are stored in the memory, control signals are generated with the commands, and braking control signals for actuating the braking unit are generated with the control signals such that gripping is performed with a gripping force greater than the normal gripping force. This operating mode can in particular be the second operating mode described above. In order to achieve a gripping force greater than 100% of the normal gripping force, the at least one main gripper is moved in such a way that the preloading device is also elastically deformed due to the impact impulse of the main gripper, and immediately thereafter the main gripper is fixed by the braking unit. Thus, the preloading force of the preloading device serves as an additional gripping force. By combining the braking unit with the preloading device, the range of use can be further increased.

[0015] Advantageously, the control unit is further configured to generate a control signal that causes re-grasping after the first contact with the article, according to predefined grasping parameters. Re-grasping can be caused in or after all the previously described operating modes. Re-grasping works as follows: First, the control unit generates a control signal corresponding to one of the operating modes. Once the control unit detects the first contact of the at least one jaw with the article to be grasped - which can be achieved, for example, by feedback from the drive due to an increase in the drive current for the electric motor or via the communication interface by a position sensor - it can generate again a control signal for re-grasping. Subsequently, there is further feedback regarding the contact with the article. This can advantageously be cyclically repeated within a predefined time period. This makes it possible to ensure that the article has been firmly grasped without re-grasping using an external machine controller within this time period.

[0016] It is conceivable that the control unit is further configured to return, via the communication interface, a signal reporting whether the workpiece has been grasped or lost after re-grasping. This means that, after the re-grasping time period has expired, the machine controller or the operator can initiate further appropriate measures.

[0017] The object mentioned at the beginning is also achieved by a method for operating a grasping or clamping device for grasping or clamping an article, in particular for operating a grasping or clamping device according to the invention, wherein the grasping or clamping device comprises at least one and preferably two main jaws that can move towards and away from each other, a drive for driving the at least one main jaw, and a control unit for generating a control signal for actuating the drive, wherein the control unit comprises a memory in which commands and characteristic variables are stored.

[0018] It is further provided that the grasping or clamping device can be operated in at least two different operating modes, wherein the corresponding operating mode is selected according to at least one predefined grasping parameter and at least one characteristic variable stored in the memory.

[0019] By the method according to the invention, by only predefined simple grasping parameters for performing the grasping process, the grasping or clamping device can be used in a variety of ways. This simplifies the control of such a gripper during operation and simplifies the integration of such a gripper into a machine.

[0020] It is conceivable that during the assembly and / or parametrization of the gripping or clamping device, the characteristic variables stored in the memory are stored in the memory. This allows the properties of the gripper to be easily queried by the control unit and allows the plausibility of the predefined gripping parameters to be checked, in particular with regard to whether the gripping or clamping device is capable of performing the desired gripping process or which of at least two operating modes will be executed.

[0021] Advantageously, the operating modes include: a first operating mode which results in gripping with a gripping force less than or equal to the normal gripping force; a second operating mode which results in gripping with a gripping force greater than the normal gripping force; and / or a third operating mode which results in gripping with a reduced pulse. The normal gripping force is the force representing 100% of the gripping force of the gripping or clamping device. For the third operating mode, a predefined gripping speed is also considered, especially if it is lower than the gripping speed calculated based on the predefined gripping force.

[0022] It is conceivable that a control signal is generated according to the predefined gripping parameters, which causes re-gripping after the first contact with the article. Re-gripping is a time-limited process in which control signals for the gripping process are continuously generated from the start of the gripping process until the expiration of a predefined time period, and feedback on whether the article has been gripped is generated. This feedback can be provided by a sensor system not described in detail, or can be detected and generated, for example, via an increase in current in the drive controller during gripping.

[0023] This object is also achieved by a computer program having the features of claim 13. Thus, the computer program includes commands which, when the program is executed by a control unit having a controller, a memory and a communication interface, cause the control unit to perform the method according to the invention. In addition, this object is achieved by a computer-readable storage medium on which a computer program according to claim 13 is stored. In addition, this object is achieved by a data carrier signal which transmits a computer program according to claim 13.

[0024] Further details and advantageous designs of the invention can be found in the following description, on the basis of which embodiments of the invention are described and explained in more detail.

[0025] In the drawings: Figure 1 : shows a gripping device; Figure 2 : shows a schematic layout of a control device; Figure 3: shows the possibility of connecting the gripping device to the machine controller; Figure 4 : a diagram showing different gripping force curves of the gripping device; Figure 5 : a diagram showing the change in the gripping force on the article over time; and Figure 6 : a flowchart showing a method for operating the gripping device.

[0026] Figure 1 Shows a gripping device 10, which has a housing 12, main jaws 14, 16 that can move towards and away from each other, and a connection area 18 for power supply and communication. A control unit 20, a drive 22, a braking unit 24, and an elastic preloading device 26 are provided in the housing 12, where in another embodiment (not shown) of the gripping device 10, the braking unit 24 and the preloading device 26 are not provided. The connection area 18 has a control lamp 28 for visualizing status messages, a ground connection 30, a connection 32 for power supply and data transmission, and a service interface 34.

[0027] The main jaws 14, 16 can be driven via the drive 22 and move parallel to the travel axis 36. In addition, gripping fingers or other attachments (not shown) can be arranged on the main jaws 14, 16 via threads 38 and centering holes 40.

[0028] The service interface 34 can be used in particular to transfer characteristic variables, characteristic maps, and / or parameters to the gripping device 10 and store them in the memory of the control unit 20.

[0029] Figure 2 Shows a schematic diagram in which the gripping device 10 is connected to a machine controller 56 present in a control cabinet 54 via a cable 50 and a distributor 52. In addition to the machine controller 56, a terminal block 58, a power supply 60, and a safety switch device 62 are provided in the control cabinet 54. The control cabinet 54 can be provided for the machine in which the gripping device 10 is arranged; other machine components are conceivable but not shown.

[0030] The power supply 60 provides a voltage supply for the gripping device 10 and the safety switch device 62. The voltage in the control cabinet 54 can be distributed to other consumers, such as the machine controller 56, via the terminal block 58. The safety switch device 62 provides additional safety measures, especially in the case of a power failure.

[0031] The distributor 52 bundles the signals of the safety switch device 62, the machine controller 56, and the power supply in such a way that only one cable 50 is required to connect the gripping device 10 to the control cabinet 54. The communication between the machine controller 56 and the gripping device 10 via the cable 50 is in particular bidirectional, such that the gripping parameters can be predefined by the machine controller 56 of the gripping device 10 and feedback from the gripping device 10 is also possible. In particular, position data or error messages can be reported back, such that bidirectional communication takes place.

[0032] In Figure 3 it is schematically shown in Figure 3 a control unit 20 having a communication interface 70, a controller 72, and a memory 74. The control unit 20 has a housing 76. The arrows indicate signals from the machine controller 56 containing predefined gripping parameters 78. The signals are transmitted via the communication interface 70 to the controller 72.

[0033] The communication interface 70 can be addressed via analog signals and / or all common digital data transmission types, such as, in particular, CAN bus, Ethernet, Mod-Bus, IO-Link, I / O-BUS, Profinet, and other fieldbus systems or board bus systems, in particular client-server systems, where wireless data transmission types are also conceivable.

[0034] In the memory 74, characteristic variables 75 related to the type and equipment of the gripping device 10 in which the control unit 20 is used are stored. The gripping parameters 78 can include the gripping force, the gripping speed, and / or the period of re-gripping as relative values in percentage. The characteristic variables 75 can be stored in the memory 74, in particular during the assembly and / or parameterization of the gripping or clamping device 10.

[0035] Based on the predefined gripping parameters 78 and the stored characteristic variables 75 from the memory 74, the controller 72 selects the corresponding operating mode and generates control signals for operating the corresponding operating mode of the gripping device 10 according to the commands stored in the memory 74. Thus, the communication interface 70 is capable of using at least one communication channel. The generated control signals are schematically shown by arrows 80, 82, 84, where the control signal 80 is assigned to the first operating mode (basic grip), the control signal 82 is assigned to the second operating mode (strong grip), and the control signal 84 is assigned to the third operating mode (soft grip) or represents such an operating mode. These control signals 80, 82, 84 are passed to the drive 22 in the gripping device 10.

[0036] In addition, the feedback to the machine controller 56 is represented by an arrow 88. This feedback is also generated by the controller 72 and forwarded by the communication interface 70.

[0037] Figure 4 A graph 90 is shown, in which the gripping force 92 on the Y-axis is plotted relative to the length 94 of the gripping fingers that can be arranged on the main jaws 14, 16 of the gripping device 10 on the X-axis. The graph 90 shows three gripping force curves, where curve 96 and curve 98 are assigned to the first operating mode, i.e., basic gripping. Curve 96 represents the normal gripping force of the gripping device 10 with a gripping force of 100% as the relative target gripping force. Curve 98 represents 50% of the relative target gripping force. Curve 100 represents the maximum gripping force curve of the second operating mode, i.e., strong gripping, with a relative target gripping force greater than 100% (here, for example, 150%). When the machine controller 56 predefines a relative target gripping force greater than 100% as the gripping parameter 78, the second operating mode, i.e., strong gripping, is executed. In this case, the main jaws 14, 16 are moved by the drive 22 at the maximum gripping speed, such that when the main jaws 14, 16 strike the article, the elastically flexible preloading element 26 is clamped, and in the preloaded state, the controller 72 transmits a control signal to the braking unit 24 via the communication interface 70, such that the main jaws 14, 16 are fixed in the preloaded state and with an increased gripping force.

[0038] Figure 5 A graph 110 is shown, in which the gripping force curves over time of two gripping processes with different operating modes, i.e., strong gripping and soft gripping, are shown using curves 112, 114. The gripping force is plotted on the Y-axis 116, and the time is plotted on the X-axis 118. Curve 112 shows the gripping force curve of the gripping process corresponding to the second operating mode, i.e., strong gripping. Curve 114 shows the gripping force curve of the gripping process corresponding to the third operating mode, i.e., soft gripping. For both curves 112 and 114, the predefined gripping force G is the same and is reached in a stationary manner at time A of curve 112 and at time B of curve 114. Time K is the time of the first contact of the jaws 14, 16 with the article to be gripped in both gripping processes. The slopes of curves 112, 114, i.e., the time derivative of the gripping force curve or the change of force over time, are the impulses acting on the article to be gripped. The strong gripping curve 112 has a large slope and thus a large impulse. In addition, the strong gripping curve 112 shows a maximum value 120 of the gripping force as an overshoot above the predefined target gripping force G. The soft gripping curve 114 reaches the target gripping force G later than the strong gripping curve 112, but has a significantly lower slope and thus a lower impulse. The soft gripping curve 114 or the third operating mode, i.e., soft gripping, based on curve 114 also has a significantly lower overshoot 122 and is thus particularly suitable for sensitive and fragile articles.

[0039] The control unit 20 is configured to perform Figure 6The method 200 schematically shown in the figure. First, the characteristic variables 75 are stored in the memory 74 of the control unit, especially during the assembly or parameterization of the gripping or clamping device 10. The characteristic variables 75 are received via the communication interface 70 and transferred to the memory 74 and stored therein, so that the controller 72 can access them during operation. A later parameterization with modified characteristic variables 75 is conceivable during operation (e.g., during maintenance work).

[0040] During the operation of the gripping or clamping device 10, the following steps are used to perform the method 200 for selecting an operation mode. First, predefined gripping parameters 78 including a target gripping force G and optionally including a gripping speed 202 and a re-gripping parameter 204 are retrieved via the communication interface 70, and the characteristic variables 75 are retrieved from the memory 74. Based on the target gripping force G predefined by the gripping parameters 78 and the characteristic variables 75, in a first stage, a first operation mode 80 (normal gripping) or a second operation mode 82 (strong gripping) is selected in the decision block 206. If the gripping speed 202 is not predefined in the gripping parameters 78 and the predefined gripping force G is greater than 100%, the second operation mode (strong gripping) is selected. If the gripping speed 202 is predefined and the predefined gripping force G is greater than 100%, the operation mode may not be selected, and an error message 208 is generated, which is transferred to the communication interface 70. In the case where the gripping or clamping device 10 is not equipped with components for the second operation mode (strong gripping) and this is stored in the characteristic variables 75, an error message 208 is generated after such a plausibility check.

[0041] If the re-gripping parameter 204 is predefined in the gripping parameters 78, a corresponding signal for re-gripping in the selected operation mode is generated in the block 210 and the signal is transferred to the communication interface 70. If the re-gripping parameter 204 is not predefined, the signals 80, 82, 84 are passed through the decision block 210 unchanged and sent to the communication interface 70.

[0042] In block 206, if the predefined target gripping force G is equal to or lower than 100%, the first operating mode (normal gripping) is initially selected. Subsequently, in the second phase, in decision block 212, it is determined based on the predefined gripping speed 202 and the characteristic variable 204 whether the first operating mode (normal gripping) will continue to be selected, or whether the third operating mode (soft gripping) will be switched to and the corresponding signal 80 or signal 84 will be generated. If the predefined gripping speed 202 is lower than the gripping speed stored in the characteristic variable 75 for the target gripping force G, the third operating mode (soft gripping) is selected. If a re-gripping parameter 204 is predefined in the gripping parameter 78, a corresponding signal for re-gripping in the selected operating mode is generated in block 210 and the signal is passed to the communication interface 70. If the re-gripping parameter 204 is not predefined, signals 80, 82, 84 are passed through decision block 210 unchanged and are sent to the communication interface 70.

[0043] By means of the gripping device 10, different operating modes (basic gripping, strong gripping, soft gripping, re-gripping) can be provided to process gripping tasks with different requirements one after another without setting time. Furthermore, this is made possible by the fact that only a few gripping parameters 78 need to be predefined.

Claims

1. A gripping or clamping device (10) for gripping or clamping an article, comprising: at least one and preferably two main jaws (14, 16) which are movable towards and away from each other; a drive (22) for driving said at least one main jaw (14, 16); a control unit (20) comprising: - a controller (72) for generating control signals (80, 82, 84) for actuating said drive (22), - a memory (74) in which commands and characteristic variables (75) are stored, and - a communication interface (70) for receiving predefined gripping parameters (78), characterized in that the control unit (20) is configured such that: - commands for at least two different operating modes for operating the gripping or clamping device (10) are stored in the memory (74), and when processed by the controller (72), the controller (72) generates control signals (80, 82, 84) for the corresponding operating modes; - wherein the operating mode corresponding to the generated control signals (80, 82, 84) is selected according to at least one predefined gripping parameter (78) and at least one characteristic variable (75) stored in the memory (74).

2. The gripping or clamping device (10) according to claim 1, wherein the predefined gripping parameter (78) represents a target gripping force (G).

3. The gripping or clamping device (10) according to claim 1 or 2, wherein the predefined gripping parameter (78) represents an absolute or relative target gripping force (G).

4. The gripping or clamping device (10) according to any one of the preceding claims, wherein the control unit (20) is further configured to calculate the gripping speed of the corresponding main jaws (14, 16) according to the predefined gripping parameter (78).

5. The gripping or clamping device (10) according to any one of the preceding claims, wherein the control unit (20) is further configured to store in the memory (74) commands for the following operating modes: - a first operating mode, in which control signals (80, 82, 84) for gripping with a gripping force less than or equal to a normal gripping force are generated; - a second operating mode, in which control signals (80, 82, 84) for gripping with a gripping force greater than the normal gripping force are generated; and / or - a third operating mode, in which control signals (80, 82, 84) for gripping with a reduced pulse are generated.

6. The gripping or clamping device (10) according to any one of the preceding claims, wherein the gripping or clamping device (10) has a braking unit (24) for fixing the at least one main jaw (14, 16) against an elastically flexible preloading device (26), One of the characteristic variables (75) stored in the memory (74) represents the presence of the braking unit (24); and The control unit (20) is further configured such that commands for the operating mode are stored in the memory (74), control signals (80, 82, 84) are generated with the commands, and a braking control signal for actuating the braking unit (24) is generated with the control signals (80, 82, 84) such that gripping is performed with a gripping force greater than the normal gripping force.

7. The gripping or clamping device (10) according to any one of the preceding claims, wherein, The control unit (20) is further configured such that control signals (80, 82, 84) that cause re-gripping after the first contact with the article are generated according to the predefined gripping parameters (78).

8. The gripping or clamping device (10) according to claim 7, wherein, The control unit (20) is further configured such that after re-gripping, a signal (88) reporting whether the workpiece is gripped or lost is returned via the communication interface (70).

9. A method for operating a gripping or clamping device (10) for gripping or clamping an article, the method being particularly for operating a gripping or clamping device (10) according to at least one of the preceding claims, wherein, The gripping or clamping device (10) comprises: - At least one and preferably two main jaws (14, 16) that are movable towards and away from each other; - A drive (22) for driving the at least one main jaw (14, 16); - A control unit (20) for generating control signals (80, 82, 84) for actuating the drive (22), wherein the control unit (20) includes a memory (74) in which characteristic variables (75) are stored, and characterized in that the gripping or clamping device (10) is operable in at least two different operating modes, wherein a corresponding operating mode is selected according to at least one predefined gripping parameter (78) and at least one characteristic variable (75) stored in the memory (74).

10. The method according to claim 9, wherein, The characteristic variables (75) stored in the memory (74) are stored in the memory (74) during the assembly and / or parameterization of the gripping or clamping device (10).

11. The method (200) according to claim 9 or 10, wherein, The operating modes include: A first operating mode that causes gripping with a gripping force less than or equal to the normal gripping force; A second operating mode that causes gripping with a gripping force greater than the normal gripping force; and / or A third operating mode that causes gripping with a reduced pulse.

12. The method (200) according to claim 9, 10 or 11, wherein, Generate control signals (80, 82, 84) according to the predefined gripping parameters (78), the control signals (80, 82, 84) causing a regripping after a first contact with the article.

13. A computer program comprising instructions which, when the program is executed by a control unit having a controller (72), a memory (74) and a communication interface (70), cause the control unit to perform the method (200) according to any one of claims 9 to 12.

14. A computer-readable storage medium having stored thereon the computer program according to claim 13.

15. A data carrier signal which transmits the computer program according to claim 13.

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