Gripping or clamping device for gripping or clamping an article in different operating modes and method therefor - Patent Application 20070122999

Abstract

A gripping or clamping device (10) for gripping or clamping an article, comprising at least one, preferably two, main jaws (14, 16) movable toward and away from each other, a drive (22) for driving the at least one main jaw (14, 16), and a control unit (20), the control unit (20) comprising a controller (72) for generating control signals (80, 82, 84) for actuating the drive (22), a memory (74) in which command and characteristic variables (75) are stored, and a communication interface (200) for receiving pre-configurable gripping parameters (78). and a control unit (20) configured to store commands for at least two different operating modes for operating the gripping or clamping device (10) in a memory (74), the commands being processed by a controller (72) to cause the controller (72) to generate control signals (80, 82, 84) for the corresponding operating modes, the selection of which operating mode control signal (80, 82, 84) is generated being a function of at least one pre-settable gripping parameter (78) and at least one characteristic variable (75) stored in the memory (74).

Description

[Technical Field]

[0001] The present invention relates to a gripping or clamping device for gripping or clamping an article, comprising at least one, and preferably two, main jaws movable towards and away from each other, and to a method of operating such a gripping or clamping device. [Background technology]

[0002] From DE 10013022 A1, a gripping or clamping device is known, which is provided with two main jaws that can be moved towards or away from one another, and which are operatively connected to an actuating piston via a gearbox, in particular a keyhead gearbox, and a piston rod, the actuating piston being in contact with two piston chambers, and the main jaws move towards or away from one another depending on the pressure in one or the other piston chamber.

[0003] EP 1 905 549 A1 discloses a gripping device with a rotary drive and two slides synchronized by a synchronizing gear, each slide being provided with a pawl for meshing with the synchronizing gear.

[0004] From EP 3 359 351 B1 a gripping or clamping device is known which comprises a drive for driving at least one main jaw and a control unit, the control unit comprising a controller for generating control signals for actuating the drive, a memory in which command and characteristic variables are stored and a communication interface for receiving preset gripping parameters. Summary of the Invention [Problem to be solved by the invention]

[0005] The object that the present invention seeks to achieve is to provide a gripping or clamping device that can be used in a variety of ways. [Means for solving the problem]

[0006] This object is achieved by a gripping or clamping device for gripping and clamping articles according to claim 1. The drive can be designed as an electric drive with an electric motor, a motor controller, and a gearbox, or as a pneumatic drive. Preferably, the gripping or clamping device comprises a housing, in which the control unit is arranged. It is also conceivable that the drive is arranged in the housing. It is also conceivable that the characteristic variables are derived from characteristic maps, or that configuration data is stored in a memory during manufacture of the gripper or control unit, and / or that parameterization is performed. Preferably, the communication interface is capable of transmitting 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 the commands are processed by the controller, they cause the controller to generate a control signal for the corresponding operating mode, and the selection of the operating mode for which the control signal is generated is made depending on at least one pre-definable grip parameter and at least one characteristic variable stored in the memory.

[0008] This has the advantage that the way in which the gripping or clamping device grips or clamps an article is determined by the control unit based on the transmitted gripping parameters, rather than depending directly on many parameters. This makes it possible, for example, to use the same gripping or clamping device for different gripping operations or to perform different gripping operations one after the other with a gripping or clamping device without changing the gripper. A further advantage is that the gripping parameters can be reduced to a minimum amount of data, which reduces the load on the communication interface and / or communication network of the machine in which the gripping or clamping device is used and accordingly simplifies the entire machine. Furthermore, the complexity of the gripping parameters to be transmitted can be significantly reduced, which also simplifies the implementation of the gripping or clamping device of the present invention. The characteristic variables stored in the memory can also be used by the control unit to check whether the gripping or clamping device can perform a gripping or clamping process based on the preset gripping parameters, thereby protecting the gripping or clamping device and the gripped article.

[0009] The control unit may be configured such that in a first step the controller first selects the operating mode based on the gripping parameters and in a second step checks whether the gripping or clamping device is capable of carrying out such a gripping process based on the characteristic variables stored in the memory, and if necessary data relating to the gripping process is transmitted via the communication interface.

[0010] It is also conceivable that a predefined grip parameter represents a target grip force, i.e., the gripping or clamping device can grip a wide variety of items and be used for multiple purposes. By specifying the target grip force, the grip force can be individually adjusted to the item being gripped, allowing for proper gripping without damaging or losing the item.

[0011] Furthermore, the preconfigurable grip parameters may represent absolute or relative target grip forces. The relative target grip force is specifically preconfigured as a value between 0 and 150% of the normal grip force. The normal grip force refers to a force that represents 100% of the grip force of the gripping or clamping device. The relative target grip force has the advantage that the data exchanged in the machine controller communicating with the control unit via the communication interface is simplified, thus making it easier for the operator to set the gripper.

[0012] Advantageously, the control unit is further adapted to calculate a corresponding gripping speed of the corresponding main jaw depending on the predefinable gripping parameters. Furthermore, when the main jaws or gripping fingers arranged on the main jaws strike a workpiece, a corresponding control signal is advantageously generated such that pulses are reduced compared to gripping processes at static gripping speeds, so that the gripping or clamping device of the present invention can be used to grip delicate and non-delicate items without requiring different grippers or swapping grippers between different gripping processes to implement different operating modes.

[0013] It is conceivable that the control unit is further configured to store commands for the first, second, and / or third operating modes in the memory. In the first operating mode, a control signal is generated that results in a grip with a grip force equal to or less than a normal grip force. In the second operating mode, a control signal is generated that results in a grip with a grip force greater than a normal grip force. In the third operating mode, a control signal is generated that results in a grip with a reduced pulse. By providing different operating modes, different objects can be advantageously gripped or clamped. The third operating mode includes a preset gripping parameter that includes a preset gripping speed in addition to a preset gripping force when the preset gripping speed is lower than the calculated gripping speed. Gripping more slowly reduces the kinetic energy of the gripper's moving parts and correspondingly reduces the pulse when the jaws strike the object. This is advantageous for fragile and / or delicate objects, particularly those used in the manufacture of electronics.

[0014] It is conceivable that the gripping or clamping device has a braking unit for fixing at least one main jaw against the elastically flexible pretensioning means, and one of the characteristic variables stored in the memory indicates the presence of the braking unit. It is conceivable that the pretensioning means is made at least partially of an elastically flexible material, such as an elastomer block or a spring element. Furthermore, the control unit may be further configured to store operating mode commands in the memory, generate a control signal from the memory, and generate a braking control signal from the control signal for activating the braking unit, thereby gripping with a gripping force greater than the normal gripping force. This operating mode may particularly be the second operating mode described above. To achieve a gripping force greater than 100% of the normal gripping force, the at least one main jaw is moved by a pulse when the main jaw strikes, causing the pretensioning means to also elastically deform, and the main jaw is then fixed by the braking unit immediately thereafter. The pretensioning force of the pretensioning means acts accordingly as an additional gripping force. Providing a braking unit in conjunction with the pretensioning means further widens the range of use.

[0015] Advantageously, the control unit is further configured to generate a control signal that causes re-gripping after initial contact with the article, depending on preconfigurable gripping parameters. Re-gripping can occur in all of the above-mentioned operating modes or subsequent to them. Re-gripping works as follows: first, the control unit generates a control signal corresponding to one of the operating modes. As soon as the control unit detects that at least one jaw has first contacted the article to be gripped (this can be done, for example, by feedback from the drive unit by increasing the drive current of the electric motor, or by a position sensor via the communication interface), it again generates a control signal for re-gripping. Thereafter, there is further feedback about the contact with the article. This is advantageously repeated periodically for a preset period of time. This makes it possible to ensure that the article is reliably gripped for a certain period of time without using an external machine controller for re-gripping.

[0016] The control unit may further be configured such that after re-gripping, a signal is reported via the communication interface as to whether the workpiece has been gripped or lost, meaning that further appropriate measures can be initiated by the machine controller or an operator after the re-gripping period has expired.

[0017] The object stated at the outset is also achieved by a method for operating a gripping or clamping device for gripping or clamping an article, in particular by a method for operating a gripping or clamping device according to the invention, the gripping or clamping device comprising at least one, preferably two, main jaws movable towards and away from each other, a drive for driving the at least one main jaw, and a control unit for generating control signals for operating the drive, the control unit comprising a memory in which commands and characteristic variables are stored.

[0018] Furthermore, the gripping or clamping device is operable in at least two different operating modes, the corresponding operating mode being selected depending on at least one pre-definable gripping parameter (78) and at least one characteristic variable (75) stored in said memory (74).

[0019] The method of the present invention allows the gripping or clamping device to be used in a variety of ways by presetting only simple gripping parameters for carrying out the gripping process, which simplifies the control of such grippers during operation and makes it easier to integrate such grippers into machines.

[0020] It is conceivable that the characteristic variables stored in the memory are stored in the memory during assembly and / or parameterization of the gripping or clamping device, so that the characteristics of the gripper can be easily queried by the control unit and, in particular, the validity of the preset gripping parameters can be checked, as to whether the gripping or clamping device is able to carry out the desired gripping process or which of the at least two operating modes is being carried out.

[0021] Advantageously, the operating modes include a first operating mode resulting in a grip with a grip force equal to or less than the normal grip force, a second operating mode resulting in a grip with a grip force greater than the normal grip force, and / or a third operating mode resulting in a grip with a reduced pulse, where the normal grip force is a force representing 100% of the grip force of the gripping or clamping device. In the third operating mode, a preset grip speed is also taken into account, in particular if it is below a grip speed calculated based on the preset grip force.

[0022] It is conceivable that a control signal is generated that causes re-gripping after initial contact with the article depending on pre-configurable gripping parameters. Re-gripping is a time-limited process in which a control signal for the gripping process is generated continuously from the start of the gripping process until a pre-configured time has elapsed, generating feedback as to whether the article has been gripped. This feedback may be provided by a sensor system, not described in detail, or may be detected and generated, for example, by an increase in current during gripping in the drive controller.

[0023] This object is likewise achieved by a computer program having the features of claim 13. The computer program therefore comprises commands which, when the program is executed by a control unit comprising a controller (72), a memory (74) and a communication interface (70), cause the latter to carry out the inventive method (200). Furthermore, the object is achieved by a computer-readable storage medium having stored thereon a computer program as claimed in claim 13. Furthermore, the object is achieved by a data carrier signal carrying the computer program as claimed in 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 explained in more detail. [Brief explanation of the drawings]

[0025] [Figure 1] 1 shows a gripping device. [Figure 2] 1 shows a schematic layout of the control device. [Figure 3] The possibility of connecting the gripping device to the machine controller is shown. [Figure 4] 1 shows a diagram of different grip force curves for a gripping device. [Figure 5] 1 shows a graph of the change in grip strength of an item over time. [Figure 6]1 shows a flowchart of a method for operating a gripping device. DETAILED DESCRIPTION OF THE INVENTION

[0026] 1 shows a gripping device 10 with a housing 12, two main jaws 14, 16 that can move towards or away from one another, and a connection area 18 for power supply and communication. A control unit 20, a drive 22, a braking unit 24 and a resilient pretensioning means 26 are arranged in the housing 12, the braking unit 24 and the pretensioning means 26 being absent in a further embodiment of the gripping device 10 (not shown). The connection area 18 contains a control lamp 28 for visualizing status messages, a ground connection 30, a connection 32 for the power supply and data transmission, and a service interface 34.

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

[0028] The service interface 34 can be used, inter alia, 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] 2 shows diagrammatically how the gripping device 10 is connected via a cable 50 and a distributor 52 to a machine controller 56 in a control cabinet 54. In addition to the machine controller 56, the control cabinet 54 also contains a terminal block 58, a power supply 60, and a safety switch device 62. The control cabinet 54 can be located on the machine on which the gripping device 10 is to be installed. Further machine components are also possible but are not shown.

[0030] A power supply 60 supplies voltage to the gripping device 10 and a safety switch device 62. The voltage within the control cabinet 54 may be distributed to other consumers, such as the machine controller 56, via terminal blocks 58. The safety switch device 62 provides an additional measure of safety, especially in the event 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 so that only one cable 50 is required to connect the gripping device 10 to the control cabinet 54. The communication via the cable 50 between the machine controller 56 and the gripping device 10 is particularly bidirectional, so that gripping parameters can be pre-set by the machine controller 56 of the gripping device 10 and feedback from the gripping device 10 is also possible. In particular, position data and error messages can be reported so that bidirectional communication takes place.

[0032] 3, the control unit 20 is shown schematically with a communications interface 70, a controller 72, and a memory 74. The control unit 20 has a housing 76. Arrows represent signals from the machine controller 56, including pre-configurable grip parameters 78. The signals are sent to the controller 72 via the communications interface 70.

[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 field bus systems or circuit board bus systems, in particular client-server systems; wireless data transmission types can also be envisaged.

[0034] The memory 74 stores characteristic variables 75 relating to the type and equipment of gripping device 10 with which the control unit 20 is used. Grip parameters 78 may include grip force (in percentage) as a relative value, grip speed and / or time period for re-gripping. The characteristic variables 75 may be stored in the memory 74 especially during assembly and / or parameterization of the gripping or clamping device 10.

[0035] Based on the preset grip parameters 78 and the characteristic variables 75 stored in the memory 74, the controller 72 selects a corresponding operating mode and generates, from the commands stored in the memory 74, control signals for the corresponding operating mode for operating the gripping device 10. Thus, the communication interface 70 can use at least one communication channel. The generated control signals are indicated schematically by arrows 80, 82, and 84, where the control signal 80 is assigned to a first operating mode (BasicGrip), the control signal 82 is assigned to a second operating mode (StrongGrip), and the control signal 82 is assigned to a third operating mode (SoftGrip), or represent these operating modes. These control signals 80, 82, and 84 are passed to the drive unit 22 of the gripping device 10.

[0036] Additionally, feedback to the machine controller 56 is represented by arrow 88. Feedback is also generated by the controller 72 and transferred by the communications interface 70.

[0037] FIG. 4 shows a diagram 90 in which grip force 92 on the Y-axis is plotted against grip finger length 94 that can be positioned in the main jaws 14, 16 of the gripping device 10 on the X-axis. Diagram 90 shows three grip force curves, with curves 96 and 98 assigned to a first operating mode, BasicGrip. Curve 96 represents the normal grip force of the gripping device 10, with a relative target grip force of 100%. Curve 98 represents 50% of the relative target grip force. Curve 100 represents the maximum grip force curve for a second operating mode, StrongGrip, which is greater than 100% of the relative target grip force, e.g., 150%. The second operating mode, StrongGrip, is executed when the machine controller 56 presets a relative target grip force of 100% or greater as the grip parameter 78. In this case, the main jaws 14, 16 are moved at maximum gripping speed by the drive unit 22, and the elastically flexible pretensioning element 26 is clamped when the main jaws 14, 16 contact the article, and in the pretensioned state, the controller 72 sends a control signal to the braking unit 24 via the communication interface 70 so that the main jaws 14, 16 are fixed under pretension with increased gripping force.

[0038] FIG. 5 shows a diagram 110 illustrating the grip force curves over time for two gripping processes using different operating modes, StrongGrip and SoftGrip, using curves 112 and 114. Grip force is plotted on the Y-axis 116 and time on the X-axis 118. Curve 112 shows the grip force curve for a gripping process corresponding to a second operating mode, StrongGrip. Curve 114 shows the grip force curve for a gripping process corresponding to a third operating mode, SoftGrip. In both curves 112 and 114, the preset grip force G is the same and reaches a steady state at time A for curve 112 and time B for curve 114. Time K is the time when the jaws 14, 16 first contact the gripped object in both gripping processes. The slopes of curves 112, 114, i.e., the time derivatives of the grip force curves or the change in force over time, represent the pulse acting on the gripped object. Curve 112 for StrongGrip has a higher slope and therefore a larger pulse. Additionally, the StrongGrip curve 112 exhibits a maximum grip force 120 as an overshoot above the preset target grip force G. The SoftGrip curve 114 reaches the target grip force G later than the StrongGrip curve 112, but with a significantly lower slope, resulting in a smaller pulse. The SoftGrip curve 114, or the third operating mode on which it is based, also exhibits a significantly lower overshoot 122, making it particularly suitable for delicate and fragile items.

[0039] The control unit 20 is configured to execute a method 200 as shown diagrammatically in Fig. 6. First, characteristic variables 75 are stored in the memory 74 of the control unit, in particular during assembly or parameterization of the gripping or clamping device 10. The characteristic variables 75 are received via the communication interface 70, passed to the memory 74 and stored therein for access by the controller 72 during operation. Subsequent parameterization with changed characteristic variables 75 is conceivable during operation, for example during maintenance work.

[0040] The method 200 for selecting an operating mode is performed during operation of the gripping or clamping device 10 using the following steps: First, preset grip parameters 78, including a target grip force G and, optionally, a grip velocity 202 and re-gripping parameters 204, are retrieved via the communication interface 70, and the characteristic variables 75 are retrieved from the memory 74. Based on the target grip force G preset by the grip parameters 78 and the characteristic variables 75, either a first operating mode 80 (NormalGrip) or a second operating mode 82 (StrongGrip) is selected in a first-stage decision block 206. If the grip parameters 78 do not include a preset grip velocity 202 and the preset grip force G is greater than 100%, the second operating mode (StrongGrip) is selected. If the grip velocity 202 and the preset grip force G are greater than 100%, the operating mode cannot be selected, and an error message 208 is generated and passed to the communication interface 70. If the gripping or clamping device 10 does not have components for the second operating mode (StrongGrip) and this is stored in the characteristic variable 75, an error message 208 is generated after such a validity check.

[0041] If the re-grip parameters 204 are preset in the grip parameters 78, then corresponding signals for regrip in the selected operating mode are generated in block 210 and passed to the communication interface 70. If the re-grip parameters 204 are not preset, then the signals 80, 82, 84 pass through the decision block 210 unchanged and are sent to the communication interface 70.

[0042] In block 206, if the preset target grip force G is less than or equal to 100%, the first operating mode (NormalGrip) is initially selected. Subsequently, in a second step in decision block 212, it is determined based on the preset grip speed 202 and characteristic variable 204 whether the first operating mode (NormalGrip) remains selected or whether a switch to the third operating mode (SoftGrip) occurs and a corresponding signal 80 or 84 is generated. If the preset grip speed 202 is lower than the grip speed stored in characteristic variable 75 for the target grip force G, the third operating mode (SoftGrip) is selected. If a re-grip parameter 204 has been preset in grip parameters 78, a corresponding signal for re-gripping in the selected operating mode is generated in block 210 and passed to communication interface 70. If a re-grip parameter 204 has not been preset, signals 80, 82, and 84 pass through decision block 210 unchanged and are sent to communication interface 70.

[0043] The gripping device 10 can offer different operating modes (BasicGrip, StrongGrip, SoftGrip, Re-Grip) allowing for successively different gripping tasks with little setup time, further made possible by the fact that only a few gripping parameters 78 need to be pre-defined.

Claims

1. At least one, preferably two, main jaws (14, 16) movable toward and away from each other; a drive unit (22) for driving the at least one main jaw (14, 16); a control unit (20); A gripping or clamping device (10) for gripping or clamping an article, the control unit (20) comprising: a controller (72) for generating control signals (80, 82, 84) for actuating said drive (22); a memory (74) in which command and characteristic variables (75) are stored; a communication interface (70) for receiving preconfigurable grip parameters (78); Including, The control unit (20) - commands for at least two different operating modes for operating the gripping or clamping device (10) are stored in the memory (74), which commands, when processed by the controller (72), cause the controller (72) to generate control signals (80, 82, 84) for the corresponding operating modes; the selection of which operating mode control signal (80, 82, 84) is generated is made depending on at least one predefinable grip parameter (78) and on at least one characteristic variable (75) stored in said memory (74); The present invention is characterized in that it is configured as follows: A gripping or clamping device (10).

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

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

4. 4. The gripping or clamping device (10) according to any one of claims 1 to 3, wherein the control unit (20) is further configured to calculate a corresponding gripping speed of the corresponding main jaw (14, 16) depending on predefinable gripping parameters (78).

5. The control unit (20) further comprises: a first operating mode in which control signals (80, 82, 84) are generated that result in a grip with a grip force less than normal; a second operating mode in which control signals (80, 82, 84) are generated that result in a grip with a grip force greater than normal, and / or a third operating mode in which the control signals (80, 82, 84) are generated with reduced pulse grip; 5. The gripping or clamping device (10) according to any one of claims 1 to 4, configured to store commands for in the memory (74).

6. the gripping or clamping device (10) comprises a braking unit (24) for fixing at least one main jaw (14, 16) against a resiliently flexible pretensioning means (26), one of the characteristic variables (75) stored in the memory (74) indicates the presence of the braking unit (24); The control unit (20) is further configured to store an operating mode command in a memory (74), generate a control signal from the memory, and generate a braking control signal (80, 82, 84) for operating the braking unit (24) from the control signal, thereby performing gripping with a gripping force greater than the normal gripping force. Gripping or clamping device (10) according to any one of claims 1 to 5.

7. 7. The gripping or clamping device (10) of claim 1, wherein the control unit (20) is further configured to generate control signals (80, 82, 84) that cause re-gripping after initial contact with the item in response to pre-settable gripping parameters (78).

8. 8. The gripping or clamping device (10) of claim 7, wherein the control unit (20) is further configured to report, via the communication interface (70), a signal (88) regarding whether the workpiece has been gripped or lost after re-gripping.

9. A method for operating a gripping or clamping device (10) for gripping or clamping an object, in particular a gripping or clamping device (10) according to any one of claims 1 to 8, The gripping or clamping device (10) comprises: at least one, preferably two, main jaws (14, 16) movable towards and away from each other; a drive (22) for driving said at least one main jaw (14, 16); a control unit (20) for generating control signals (80, 82, 84) for actuating said drive (22), said control unit (20) comprising a memory (74) in which characteristic variables (75) are stored; Including, The gripping or clamping device (10) is operable in at least two different modes of operation; The corresponding operating mode is selected depending on at least one pre-definable grip parameter (78) and at least one characteristic variable (75) stored in the memory (74). characterized in that method.

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

11. The operating mode is - a first operating mode providing grip with a grip force less than normal; a second operating mode that provides gripping with a greater than normal gripping force, and / or a third operating mode providing grip with reduced pulse; 11. The method (200) of claim 9 or 10, comprising:

12. 12. The method (200) of any one of claims 9 to 11, wherein control signals (80, 82, 84) are generated in response to the pre-settable grip parameters (78) to cause re-gripping after initial contact with the item.

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

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

15. A data carrier signal carrying a computer program according to claim 13.

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