Gripping or clamping device for gripping or clamping objects in different operating modes, and method therefor

Abstract

A gripping or clamping device (10) for gripping or clamping objects and an associated method (200), with at least one and preferably two main jaws (14, 16) which can be moved towards one another and away from one another, with a drive (22) for driving the at least one main jaw (14, 16), with a control unit (20), comprising a controller (72) for generating control signals (80, 82, 84) which actuate the drive (22), a memory (74), in which commands and characteristic variables (75) are stored, and a communications interface (70) for receiving predefinable gripping parameters (78), wherein the control unit (20) is configured in such a way that 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 they are processed by the controller (72), cause the controller (72) to generate control signals (80, 82, 84) for the respective operating mode, wherein the selection for which operating modes control signals (80, 82, 84) are generated takes place depending on at least one predefinable gripping parameter (78) and on at least on one characteristic variable (75) stored in the memory (74).

Description

[0001] Title: Gripping or clamping device for gripping or

[0002] Clamping of objects in different operating modes and procedures for this

[0003] Description

[0004] The present invention relates to a gripping or clamping device for gripping or clamping objects, with at least one and preferably two base jaws that can be moved towards and away from each other, as well as a method for operating such a gripping or clamping device.

[0005] DE 10 013 022 A1 discloses a gripping or clamping device comprising two base jaws that can be moved toward and away from each other. The base jaws are coupled to a working piston via a gear mechanism, namely a wedge-hook gear mechanism, and a piston rod. The working piston defines two piston chambers; depending on the pressure applied to one or the other piston chamber, the base jaws are moved toward or away from each other.

[0006] EP 1 905 549 A1 discloses a gripping device with a rotary drive and two slides synchronized by means of a synchronous gear, wherein each slide is provided with a toothing for engagement with the synchronous gear.

[0007] From EP 3 359 351 B1 a gripping or clamping device with a drive for driving the at least one base jaw and with a control unit is known, wherein the control unit comprises a controller for generating control signals controlling the drive, a memory in which commands and parameters are stored, and a communication interface for receiving predeterminable gripping parameters.

[0008] 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.

[0009] The object is achieved with a gripping or clamping device for gripping and clamping objects according to claim 1. It is conceivable that the drive is designed as an electric drive with an electric motor, a motor controller and a gear or as a pneumatic drive. The gripping or clamping device preferably comprises a housing in which the control unit is arranged. It is conceivable that the drive is also arranged in the housing. It is further conceivable that parameters are derived from characteristic diagrams or configuration data are stored in the memory during manufacture of the gripper or the control unit and / or parameterization takes place. The communication interface can preferably also send data.

[0010] The control unit is set up in such a way that commands for at least two different operating modes for operating the gripping or clamping device are stored in the memory, which commands, when processed by the controller, cause the controller to generate control signals for the respective operating mode, wherein the selection of the operating modes for which control signals are generated is made as a function of at least one predefinable gripping parameter and of at least one characteristic value stored in the memory.

[0011] This has the advantage that the way in which the gripper or clamping device grips or clamps an object is not directly dependent on many parameters, but is determined by the control unit based on the transmitted gripping parameters. This could, for example, mean that the same gripper or clamping devices can be used for different gripping tasks, or that the gripper or clamping devices can carry out different gripping tasks one after the other without the gripper having to be converted. A further advantage is that the gripping parameters can be reduced to a minimum of data, thus reducing the load on the communication interface and / or a communication network in a machine in which the gripper or clamping device is used, and thus simplifying the entire machine.Furthermore, the implementation of a gripping or clamping device according to the invention is simplified because the complexity of the gripping parameters to be transferred can be significantly reduced. The parameters stored in the memory can also be used by the control unit to check whether the gripping or clamping device is capable of performing a gripping or clamping process based on the specified gripping parameters, which protects the gripping or clamping device and the object to be gripped.

[0012] The control unit can be configured such that, in a first step, the controller selects the operating mode based on the gripping parameters. In a second step, it checks, based on the parameters stored in the memory, whether the gripping or clamping device is capable of performing such a gripping process. If necessary, data relating to the gripping process is then sent via the communication interface.

[0013] It is conceivable that the specified gripping parameters represent a target gripping force. This allows the gripping or clamping device to grip a wide variety of objects and is versatile in its application. By specifying a target gripping force, the gripping force can be specifically adjusted to the object to be gripped, thus achieving a customized gripping action without damaging or losing the object.

[0014] It is also conceivable that the specifiable gripping parameters represent an absolute target gripping force or a relative target gripping force. A relative target gripping force is specified, in particular, as a value between 0 and 150% of a normal gripping force. The normal gripping force refers to a force that represents 100% of the gripping force of the gripping or clamping device. A relative target gripping force has the advantage of simplifying the data exchange in a machine control system that communicates with the control unit via the communication interface, thus making it easier for the operator to set up the gripper.

[0015] Advantageously, the control unit is further configured such that a corresponding gripping speed of the respective base jaw is calculated depending on the predeterminable gripping parameters.

[0016] Furthermore, appropriate control signals are advantageously generated so that when the base jaw or a gripper finger arranged on the base jaw strikes, the impulse is reduced compared to a gripping process with a static gripping speed. This allows the gripping or clamping device according to the invention to grip both delicate and less delicate objects without the need for different grippers or the need to convert the gripper between different gripping processes to implement different operating modes.

[0017] It is conceivable that the control unit is further configured such that commands are stored in the memory for a first operating mode, a second operating mode, and / or a third operating mode. The first operating mode generates control signals that lead to gripping with a gripping force less than or equal to a normal gripping force. The second operating mode generates control signals that lead to gripping with a gripping force greater than the normal gripping force. The third operating mode generates control signals that lead to gripping with reduced impulses. By providing the various operating modes, different objects can be advantageously gripped or clamped. The third operating mode includes, in addition to the specified gripping force, the specified gripping speed as a specified gripping parameter, if this is below the calculated

[0018] gripping speed. By gripping more slowly, the kinetic energy in the moving components of the gripper is reduced and thus also the impulse when the jaw hits the object. This is particularly advantageous for brittle and / or fragile objects, which can be used in particular in electronics manufacturing. It is conceivable that the gripping or clamping device has a braking unit for fixing the at least one base jaw against elastically flexible pretensioning means, wherein one of the parameters stored in the memory represents the presence of the braking unit. It is conceivable that the pretensioning means are made of at least partially elastically flexible material, such as elastomer blocks or spring elements.It can further be provided that the control unit is further configured such that commands for an operating mode are stored in the memory, with which control signals are generated with which brake control signals for actuating the brake unit are generated, so that gripping occurs 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 base jaw is moved in such a way that the pretensioning means are elastically deformed due to the impact impulse of the base jaws, with the base jaw being fixed immediately afterwards by means of the brake unit. The pretensioning forces of the pretensioning means therefore act as additional gripping forces. By providing a brake unit in conjunction with the pretensioning means, the area of ​​application can be further expanded.

[0019] Advantageously, the control unit is further configured such that, depending on the predeterminable gripping parameters, control signals are generated which initiate a follow-up gripping after an initial contact with the object. The follow-up gripping can be initiated in all of the previously described operating modes or can follow on from them. The follow-up gripping works as follows: First, the control unit generates control signals corresponding to one of the operating modes. As soon as the control unit detects an initial contact of the at least one jaw with the object to be gripped - this can be done, for example, by feedback from the drive due to an increase in the drive current for the electric motor or by position sensors via the communication interface - it generates further control signals for a follow-up gripping. Subsequently, there is further feedback about contact with the object.This is advantageously repeated cyclically for a predefined period of time. This ensures that the object has been securely gripped without requiring an external machine control system to continue gripping for the specified period.

[0020] It is conceivable that the control unit is further configured so that, after re-gripping, signals are returned via the communication interface indicating whether the workpiece has been gripped or lost. This allows the machine control system or an operator to initiate appropriate further measures after the re-gripping period has elapsed.

[0021] The object mentioned at the outset is also achieved by a method for operating a gripping or clamping device for gripping or clamping objects, in particular for operating a gripping or clamping device according to the invention, wherein the gripping or clamping device comprises at least one and preferably two base jaws which can be moved towards and away from one another, a drive for driving the at least one base jaw, and a control unit for generating control signals which control the drive, wherein the control unit comprises a memory in which commands and parameters are stored.

[0022] It is further provided that the gripping or clamping device can be operated in at least two different operating modes, wherein the respective operating mode is selected as a function of at least one predeterminable gripping parameter and of at least one characteristic value stored in the memory.

[0023] A method according to the invention allows a gripping or clamping device to be used in a variety of ways by specifying only simple gripping parameters for carrying out a gripping process. This simplifies the control of such a gripper during operation and the integration of such a gripper into a machine.

[0024] It is conceivable that the characteristic value stored in the memory is stored during assembly and / or during parameterization of the gripper or clamping device. This allows the properties of the gripper to be easily queried by the control unit and the plausibility of the specified gripping parameters to be verified, in particular whether the gripper or clamping device can perform the desired gripping process or which of the at least two operating modes is being executed.

[0025] Advantageously, the operating modes comprise a first operating mode that results in gripping with a gripping force less than or equal to a normal gripping force, a second operating mode that results in gripping with a gripping force greater than the normal gripping force, and / or a third operating mode that results in reduced-impulse gripping. The normal gripping force refers to a force that represents 100% of the gripping force of the gripping or clamping device. For the third operating mode, a predetermined gripping speed is included, in particular if it is below the gripping speed calculated based on the predetermined gripping force.

[0026] It is conceivable that, depending on the predeterminable gripping parameters, control signals are generated that trigger a follow-up gripping action after initial contact with the object. Follow-up gripping is a time-limited process in which, from the moment a gripping action is initiated, control signals for a gripping action are generated continuously until a predeterminable period of time has elapsed, and feedback is generated as to whether the object has been gripped. The feedback can be provided by means of a sensor system (not described in detail) or, for example, detected and generated via a current increase during gripping in the drive control. This object is also achieved by a computer program having the features of claim 13.Accordingly, the computer program comprises instructions which, when executed by a control unit having a controller, a memory, and a communication interface, cause the control unit to carry out the method according to the invention. Furthermore, the object is achieved by a computer-readable storage medium on which the computer program according to claim 13 is stored. Furthermore, the object is achieved by a data carrier signal which transmits the computer program according to claim 13.

[0027] Further details and advantageous embodiments 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.

[0028] It shows :

[0029] Figure 1 : a gripping device;

[0030] Figure 2: a schematic structure of a control device;

[0031] Figure 3 : a possibility of connecting the gripping device to a machine control system;

[0032] Figure 4 : a diagram of different gripping force curves of the gripping device; Figure 5 : a diagram of the gripping force change on a

[0033] object over time; and

[0034] Figure 6: a flow diagram of a method for operating the gripping device.

[0035] Figure 1 shows a gripping device 10 with a housing 12, two base jaws 14, 16 that can be moved towards and away from each other, and a connection area 18 for a power supply and communication. Provided in the housing 12 are a control unit 20, a drive 22, a braking unit 24, and elastic preloading means 26, although the braking unit 24 and the preloading means 26 are not provided in a further embodiment of the gripping device 10 (not shown). The connection area 18 has control lamps 28 for visualizing status messages, a ground connection 30, a connection for a power supply and data transmission 32, and a service interface 34.

[0036] The base jaws 14, 16 are driven by the drive 22 and move parallel to a travel axis 36. Furthermore, gripping fingers or other accessories (not shown) can be arranged on the base jaws 14, 16 via the threads 38 and the centering tubes 40.

[0037] The service interface 34 can be used in particular to transfer characteristics, characteristic maps and / or parameters to the gripping device 10 and to store them in a memory of the control unit 20.

[0038] Figure 2 shows a schematic representation in which the gripping device 10 is connected via a cable 50 and a distributor 52 to a machine control 56 located in a control cabinet 54. In addition to the machine control 56, the control cabinet 54 contains a terminal block 58, a power supply 60, and a safety switching device 62. The control cabinet 54 can be provided for a machine in which the gripping device 10 is arranged; further machine components are conceivable but not shown.

[0039] The power supply unit 60 provides a voltage supply for the gripping device 10 and the safety switching device 62. The voltage in the control cabinet 54 can be distributed to other consumers, such as the machine controls 56, via the terminal block 58. The safety switching device 62 provides additional safety measures, particularly in the event of a power failure.

[0040] The distributor 52 bundles the signals from the safety switching device 62 and the machine control 56, as well as the power supply, so that only one cable 50 is required to connect the gripping device 10 to the control cabinet 54. Communication via the cable 50 between the machine control 56 and the gripping device 10 is, in particular, bidirectional, so that gripping parameters can be specified by the machine control 56 or the gripping device 10, and feedback from the gripping device 10 is also possible. In particular, position data or error messages can be fed back, so that bidirectional communication takes place.

[0041] Figure 3 shows a schematic diagram of the control unit 20 with a communication interface 70, a controller 72, and a memory 74. The control unit 20 has a housing 76. An arrow symbolizes the signals from the machine control 56, which contain the predeterminable gripping parameters 78. The signals are transmitted to the controller 72 via the communication interface 70.

[0042] 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, whereby wireless data transmission types are also conceivable.

[0043] Memory 74 contains parameters 75 relating to the type and configuration of the gripping device 10 in which the control unit 20 is used. Gripping parameters 78 may include the gripping force as a relative value in percent, the gripping speed, and / or the re-gripping period. Parameters 75 may be stored in memory 74, particularly during assembly and / or during parameterization of the gripping or clamping device 10.

[0044] Based on the predetermined gripping parameters 78 and the stored characteristics 75 from the memory 74, the controller 72 selects the appropriate operating mode and generates control signals from commands stored in the memory 74 for the appropriate operating mode to operate the gripping device 10. The communication interface 70 is therefore able to operate at least one communication channel. The generated control signals are schematically represented by the arrows 80, 82, 84, with the control signals 80 being assigned to a first operating mode (BasicGrip), the control signals 82 being assigned to a second operating mode (StrongGrip), and the control signals 82 being assigned to a third operating mode (SoftGrip) or representing such an operating mode. These control signals 80, 82, 84 are passed on to the drive 22 in the gripping device 10.

[0045] Furthermore, the arrow 88 represents the feedback to the machine control system 56. The feedback is also generated by the controller 72 and forwarded by the communication interface 70.

[0046] Figure 4 shows a diagram 90 in which the gripping force 92 on the Y-axis is plotted against the length 94 of the gripping fingers arranged on the base jaws 14, 16 of the gripping device 10 on the X-axis. Diagram 90 shows three gripping force curves, with curve 96 and curve 98 being assigned to the first operating mode, BasicGrip. Curve 96 represents the normal gripping force of the gripping device 10 with 100% gripping force 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, StrongGrip, with greater than 100%, here for example 150%, of the relative target gripping force. The second operating mode StrongGrip is executed when the machine control 56 specifies a relative target gripping force of more than 100% as gripping parameter 78.In this case, the base jaws 14, 16 are moved by the drive 22 at a maximum gripping speed, so that the elastically flexible pre-tensioning elements 26 are tensioned when the base jaws 14, 16 hit the object and, in the pre-tensioned state, the controller 72 transmits control signals to the brake unit 24 via the communication interface 70, so that the base jaws 14, 16 are fixed under pre-tension and with increased gripping force.

[0047] Figure 5 shows a diagram 110 in which the temporal gripping force curve of two gripping processes with the different operating modes StrongGrip and SoftGrip is represented by curves 112 and 114. The gripping force is plotted on the Y-axis 116 and time on the X-axis 118. Curve 112 shows the gripping force curve of a gripping process according to the second operating mode StrongGrip. Curve 114 shows the gripping force curve of a gripping process according to the third operating mode SoftGrip. In both curves 112 and 114, the predetermined gripping force G is the same and is reached in a steady state at time A by curve 112 and at time B by curve 114. Time K is the time of initial contact of the jaws 14, 16 with the object to be gripped in both gripping processes. The gradient of the curves 112 , 114 , i.e. the time derivative of the gripping force curve or .the change in force over time is the impulse acting on the object to be gripped. Curve 112 of the StrongGrip has a steep gradient and therefore a high impulse. In addition, the StrongGrip curve 112 has a maximum 120 of the gripping force as an overshoot above the specified target gripping force G. The SoftGrip curve 114 reaches the target gripping force G later than the StrongGrip curve 112, but has a significantly lower gradient and therefore a low impulse. The SoftGrip curve 114 or the third operating mode SoftGrip on which curve 114 is based also has a significantly lower overshoot 122 and is therefore particularly suitable for sensitive and fragile objects.

[0048] The control unit 20 is configured to execute the method 200 schematically illustrated in Figure 6. Initially, parameters 75 are stored in the memory 74 of the control unit, particularly during assembly or parameterization of the gripping or clamping device 10. The parameters 75 are received via the communication interface 70 and forwarded to the memory 74 and stored there so that the controller 72 can access them during operation. Later parameterization with modified parameters 75 during operation, for example during maintenance work, is conceivable.

[0049] The method 200 for selecting the operating mode is carried out during operation of the gripping or clamping device 10 using the following steps. First, the specified gripping parameters 78, which include the target gripping force G and optionally the gripping speed 202 and a follow-up gripping parameter 204, are retrieved from the memory 74 via the communication interface 70, as well as the parameters 75. Based on the target gripping force G specified by the gripping parameters 78 and the parameters 75, either the first operating mode 80 (NormalGrip) or the second operating mode 82 (StrongGrip) is selected in a decision block 206 in a first stage. If no gripping speed 202 is specified in the gripping parameters 78 and the specified gripping force G is greater than 100%, the second operating mode (StrongGrip) is selected.If a gripping speed 202 and the specified gripping force G is greater than 100%, no operating mode can be selected and an error message 208 is generated which is sent to the communication interface 70. In the case in which the gripping or clamping device 10 is not equipped with the components for the second operating mode (StrongGrip) and this is stored in the parameters 75, an error message 208 is generated after such a plausibility check. If a follow-up gripping parameter 204 is specified in the gripping parameters 78, corresponding signals for follow-up gripping in the selected operating mode are generated in a block 210 and sent to the communication interface 70. If no follow-up gripping parameters 204 are specified, the signal 80, 82, 84 is passed unchanged through the decision block 210 and sent to the communication interface 70.

[0050] In block 206, the first operating mode (NormalGrip) is initially selected if the specified target gripping force G is equal to or below 100%. Subsequently, in a second stage, in decision block 212, a decision is made based on the specified gripping speed 202 and the parameters 204 as to whether the first operating mode (NormalGrip) is still selected or whether to switch to the third operating mode (SoftGrip) and corresponding signals 80 or 84 are generated. If the specified gripping speed 202 is below a value stored in the parameters 75 for the target gripping force G,

[0051] Gripping speed, the third operating mode (SoftGrip) is selected. If a follow-up gripping parameter 204 is specified in the gripping parameters 78, then corresponding signals for follow-up gripping in the selected operating mode are generated in block 210 and sent to the communication interface 70. If no follow-up gripping parameters 204 are specified, the signal 80, 82, 84 is passed unchanged through the decision block 210 and sent to the communication interface 70. With the gripping device 10, various

[0052] Operating modes (BasicGrip StrongGrip, SoftGrip, re-gripping) are provided to process gripping tasks with different requirements one after the other without setup times.

[0053] Furthermore, this is made possible by the fact that only a few gripping parameters 78 have to be specified.

Claims

Patent claims Gripping or clamping device (10) for gripping or clamping objects, with at least one and preferably two base jaws (14, 16) movable towards and away from each other, with a drive (22) for driving the at least one base jaw (14, 16), with a control unit (20), comprising - a controller (72) for generating control signals (80, 82, 84) controlling the drive (22), - a memory (74) in which commands and parameters (75) are stored and -a communication interface (70) for receiving predeterminable gripping parameters (78), characterized in that the control unit (20) is set up in such a way, - that commands for at least two different operating modes for operating the gripping or clamping device (10) are stored in the memory (74), which, when processed by the controller (72), cause the controller (72) to generate control signals (80, 82, 84) for the respective operating mode, - wherein the selection of the operating modes for which control signals (80, 82, 84) are generated is made as a function of at least one predeterminable gripping parameter (78) and at least one characteristic variable (75) stored in the memory (74). Gripping or clamping device (10) according to claim 1, wherein the predeterminable gripping parameters (78) represent a desired gripping force (G). Gripping or clamping device (10) according to claim 1 or 2, wherein the predeterminable gripping parameters (78) represent an absolute or a relative desired gripping force (G). Gripping or clamping device (10) according to one of the preceding claims, wherein the control unit (20) is further configured such that a corresponding gripping speed of the respective base jaw (14, 16) is calculated as a function of the predeterminable gripping parameters (78).Gripping or clamping device (10) according to one of the preceding claims, wherein the control unit (20) is further configured such that commands are stored in the memory (74) for one. - first operating mode, with which control signals (80, 82, 84) are generated which lead to gripping with a gripping force less than or equal to a normal gripping force, - second operating mode, with which control signals (80, 82, 84) are generated, which lead to a gripping force greater than the normal gripping force, and / or - third operating mode, with which control signals (80, 82, 84) are generated that lead to a gripping action with reduced impulse. Gripping or clamping device (10) according to one of the preceding claims, wherein the gripping or clamping device (10) has a braking unit (24) for securing the at least one base jaw (14, 16) against elastically flexible preloading means (26), wherein one of the parameters (75) stored in the memory (74) represents the presence of the braking unit (24), and wherein the control unit (20) is further configured such that commands for an operating mode are stored in the memory (74), with which control signals (80, 82, 84) are generated, with which braking control signals for controlling the braking unit (24) are generated, so that gripping occurs with a gripping force greater than the normal gripping force.Gripping or clamping device (10) according to one of the preceding claims, wherein the control unit (20) is further configured such that, depending on the predeterminable gripping parameters (78), control signals (80, 82, 84) are generated which, after a first. Contact with the object causes a re-gripping. Gripping or clamping device (10) according to claim 7, wherein the control unit (20) is further configured such that, after the re-gripping, signals (88) are returned via the communication interface (70) indicating whether the workpiece has been gripped or lost. A method for operating a gripping or clamping device (10) for gripping or clamping objects, in particular 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 base jaws (14, 16) which can be moved towards and away from each other, - a drive (22) for driving the at least one base jaw (14, 16), - a control unit (20) for generating control signals (80, 82, 84) controlling the drive (22), wherein the control unit (20) comprises a memory (74) in which parameters (75) are stored, characterized in that the gripping or Clamping device (10) can be operated in at least two different operating modes, wherein the respective operating mode is selected depending on at least one predeterminable gripping parameter (78) and at least one characteristic variable (75) stored in the memory (74). Method according to claim 9, wherein the characteristic variable (75) stored in the memory (74) is stored in the memory (74) during assembly and / or during parameterization of the gripping or clamping device (10). Method (200) according to claim 9 or 10, wherein the operating modes comprise - a first operating mode which results in gripping with a gripping force less than or equal to a normal gripping force, - a second operating mode that results in gripping with a gripping force greater than the normal gripping force, and / or - a third operating mode, which leads to a reduced-impulse gripping. Method (200) according to claim 9, 10 or 11, wherein, depending on the predeterminable gripping parameters (78), control signals (80, 82, 84) are generated, which, after a first contact with the object, cause a subsequent gripping. Computer program, comprising instructions which, when executing the program, are executed by a control unit having a controller (72), a memory (74) and a Communication interface (70) causing it to execute the method (200) according to one of claims 9 to 12. Computer-readable storage medium on which the computer program according to claim 13 is stored. Data carrier signal that transmits the computer program according to claim 13.

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