Method and device for controlling a manipulator arrangement

Description

[0001] The present invention relates to a method and a device for controlling a manipulator arrangement with at least one manipulator, in particular a robot.

[0002] Manipulator setups are increasingly being operated outside of secure cells, i.e., outside of structured environments, where, for example, people can cross a manipulator's workspace or even work directly with a manipulator. Operating in unstructured environments can pose risks to people.

[0003] This potential danger justifies the need to control a manipulator arrangement or a manipulator in such a way that accident damage remains within an acceptable range in the event of both human and technical failure.

[0004] Typical measures for the safe control of manipulators, so-called safety functions or monitoring, include, among other things, limits on certain states of the manipulator, e.g., the working space, speed, acceleration, forces, etc.

[0005] However, monitoring systems must be reliable to reduce the potential risk to an acceptable level. According to internal practice, manipulators are now at least partially developed and built using so-called safe technology. Safe technology typically meets the requirements of application-specific standards, such as EN 13849 and / or IEC 61508. Safe technology can include, among other things, sensors, data processing, and / or communication links, and usually encompasses all components of a monitoring system.

[0006] To ensure the integrity of monitoring functions alongside the safety technology on the manipulator, these functions must be operated by a safety controller that also meets the requirements of the relevant safety standards. Currently, in accordance with company practice, manipulator systems are operated with a safety controller in parallel to a standard, non-safety-based controller and configured via a dedicated, safe human-machine interface. The safety controller thus operates independently of the non-safety-based controller and, at best, can only interact with it to a limited extent via dedicated communication channels.

[0007] In DE 10 2004 041 821 A1, a safety control system is disclosed in which zone-wise information about the positions of moving parts of a handling device is transmitted to a safety control system, so that the safety control system, in conjunction with the handling device control system, controls safety-relevant functions of the handling device.

[0008] DE 10 2005 011 143 A1 relates to a device for controlling at least one safety-relevant function of a robot with at least one spatially resolving sensor, in particular a camera, for monitoring a safety area of ​​the robot, an evaluation unit for processing the data supplied by the sensor, triggering means for triggering the safety-relevant function when an unauthorized object enters the safety area and means for changing the contour of the safety area depending on movement, position or operating data of the robot.

[0009] EP 1 035 953 B1 relates to a monitoring and control device for monitoring a technical system with increased safety requirements, in particular a handling device, with a control unit and actuators connected to it for carrying out hazardous actions, wherein the monitoring and control device is connected to sensors and evaluates, processes and controls their states.

[0010] DE 10 2008 015 948 A1 discloses a method for monitoring a manipulator, in particular a robot. The method comprises the steps of: performing at least one functional test of the manipulator and performing at least one parameter monitoring of the manipulator, wherein the functional tests to be performed are selected from a plurality of functional tests depending on the parameter monitoring to be performed.

[0011] EP 2 315 093 A1 discloses a method for controlling a manipulator, in particular a robot. The method comprises the steps of: determining a target path of the manipulator; determining a motion parameter for this target path; optionally, determining a path segment with a predetermined profile of a motion parameter, and automatically determining this motion parameter based on permissible motion parameters in this path segment.

[0012] DE 10 2010 048 369 A1 discloses a method for the safety monitoring of at least one manipulator, in particular a robot. The safety monitoring is implemented as a state machine which can switch between at least two states, in each of which at least one safety functionality is monitored.

[0013] The object of the present invention is to improve a manipulator arrangement.

[0014] This problem is solved by a method with the features of claim 1. Claim 12 protects a control system for carrying out a method according to the invention, claim 13 protects a computer program that executes a method according to the invention, and claim 14 protects a computer program product, in particular a storage medium, with such a computer program. The dependent claims relate to preferred embodiments.

[0015] In a method according to the invention for controlling a manipulator arrangement with one or more manipulators, a virtual target process is first specified for one or more manipulators. For example, a number of Cartesian target poses are specified, which are to be approached sequentially by a manipulator. A manipulator is, in particular, a robot and preferably movable in several degrees of freedom, especially in four, six, or seven degrees of freedom, wherein one degree of freedom is realized, in particular, by an axis of the manipulator. The manipulator arrangement has one or more controllers; preferably, each manipulator of the manipulator arrangement is equipped with a controller. Additionally or alternatively, the manipulator arrangement has an overall controller.

[0016] After a virtual target process has been specified, the manipulator system, in particular one or more manipulators of the manipulator system, executes a real actual process. For example, a manipulator following a path.

[0017] The actual process is monitored by controlling the manipulator arrangement. For example, it is monitored whether the manipulator exceeds a permissible maximum speed when following a path. Preferably, the actual process of each manipulator in the manipulator arrangement is monitored by controlling it. According to the invention, one or more monitoring points of the actual process are specified by the control system, particularly automatically. The specified monitoring points are defined based on the virtual target process.

[0018] This makes it possible to automatically generate appropriate monitoring for a given target process, especially without having to specify it separately through a safety controller.

[0019] A setting within the meaning of the present invention can comprise a configuration of a virtual target process of the manipulator arrangement, in particular of one or more manipulators of the manipulator arrangement. Additionally or alternatively, a setting can comprise a setting, in particular an automatic one, which is communicated by a controller from the environment of the manipulator arrangement. Preferably, a setting is dependent on a state of the manipulator arrangement, in particular a state of a manipulator of the manipulator arrangement and / or a tool of a manipulator of the manipulator arrangement. A setting can be dependent on a workpiece of the manipulator arrangement. Additionally or alternatively, a setting can be communicated by a device that interacts with the manipulator arrangement.

[0020] A process within the meaning of the present invention can be a process carried out purposefully by the manipulator arrangement. A process can comprise algorithmically executed information processing. In particular, a process is a process controlled by a program, which, in particular, requires a processor for its execution, preferably provided by a controller.

[0021] A process preferably comprises subprocesses which, both hierarchically and / or vertically integrated, include a sequence of processing steps leading to a final result of the subprocess. Additionally or alternatively, a process preferably comprises subprocesses which are processed in parallel, particularly concurrently, and / or sequentially, particularly one after the other. In particular, two or more manipulators of the manipulator arrangement are operated in parallel. Each manipulator is specifically assigned one or more subprocesses. The subprocesses can be executed by a controller, with the allocation of resources to each subprocess preferably being organized by a scheduling algorithm. Additionally or alternatively, two or more subprocesses can be operated by dedicated controllers, particularly such that resources are exclusively assigned to these subprocesses.A process and / or a subprocess preferably represents a real-time process.

[0022] Monitoring within the meaning of the present invention is preferably a process that performs targeted observation of devices, processes, and / or living beings, especially humans. Monitoring serves, in particular, to increase the safety of humans and machines. Preferably, monitoring serves to increase the safety of humans and devices within the manipulator arrangement. Additionally or alternatively, monitoring can also serve to increase the safety of humans and devices that interact with the manipulator arrangement and / or are located within the danger zone of the manipulator arrangement. Monitoring preferably includes a comparison of actual and target values. Monitoring can monitor limit values ​​to be observed, in particular position-dependent limit values ​​(e.g., working space, deflection of a manipulator, speed, acceleration, jerk, etc.).) relate to and / or force- and / or torque-dependent limit values, as well as combinations of these values. Additionally or alternatively, a parameter of a model, in particular an estimated model, can be monitored, wherein the model is preferably estimated based on acquired information. Monitoring is carried out in particular continuously, discretely, periodically and / or at irregular intervals, especially event-driven. According to the invention, the manipulator arrangement, in particular one or more manipulators of the manipulator arrangement, is brought into a safe state when monitoring registers a malfunction. A safe state can be achieved by an emergency stop and / or by a soft switch, in particular of certain axes of a manipulator.

[0023] According to the invention, monitoring is based on the detection of a state of the manipulator arrangement. For example, compliance with a maximum permissible speed is specified when the door of a robot cell is opened. A state can be a physical state, in particular a position, a speed, an acceleration, a jerk, a force of one or more manipulators or another device, especially a workpiece and / or a tool, of the manipulator arrangement. For the sake of simplicity, a (torsional) torque, i.e., an antiparallel force couple, is also referred to generally as force. Advantageously, monitoring can be specified depending on a specific movement of a manipulator of the manipulator arrangement.

[0024] In a preferred embodiment, monitoring is provided based on a control system. For example, monitoring is provided by an overall control system for the manipulator arrangement. A control system can, in particular, be a control system for a manipulator within the manipulator arrangement and / or another device within the manipulator arrangement. Additionally or alternatively, a control system can refer to a control unit or a device that interacts with the manipulator arrangement. Preferably, monitoring is provided based on the sequence control of the virtual actual process. Advantageously, this allows monitoring to be automatically provided by a control system depending on a specific actual process situation.

[0025] In a preferred embodiment, monitoring is based on a tool of a manipulator or manipulator assembly and / or on the workpiece being manipulated. For example, torque monitoring is specified as soon as a robot tool signals that it has gripped a component. Preferably, monitoring is based on a device that interacts with the manipulator assembly. Such a device can be a controller, another manipulator, and / or a manipulator assembly. Additionally or alternatively, such a device can be a large-area monitoring system and / or an emergency device. This advantageously allows monitoring to be specified according to the specific situation.

[0026] A state can be defined by specific components, in particular the presence or absence of certain components, of a device. For example, speed monitoring for a robot can only be specified if the robot has position sensors using safe technology. According to the invention, one or more states indicate the presence or absence of safe and / or non-safe sensors and / or actuators. Such a device can, in particular, relate to the aforementioned devices. A state can also be defined by a property of a method. Preferably, one or more states indicate the safety and / or non-safety of a method. Advantageously, this allows for the automatic monitoring of available safe components and methods.

[0027] In a preferred embodiment, a process and / or monitoring of a method according to the invention comprises several hierarchical subprocesses, in particular path planning and / or a kinematic transformation. For example, interpolation values ​​are determined from a Cartesian path plan for a robot, which serve as input for an inverse transformation from which the corresponding axis values ​​of the robot are calculated. The hierarchical subprocesses can be organized within a vertical and / or horizontal integration. The hierarchical subprocesses are preferably structured by an order relation or by a graph, in particular a directed graph. A subprocess can have one or more superior subprocesses and / or one or more subordinate subprocesses. A subprocess can represent path planning, filtering, an inverse transformation, and / or a forward transformation.This can be advantageous, allowing monitoring to be focused on specific parts of the current process.

[0028] Preferably, the control system specifies one or more monitoring parameters for a subprocess of the actual process based on a subprocess of the virtual target process. For example, interpolation values ​​calculated in the target process are compared with interpolation values ​​determined from the actual process, and it is monitored whether a maximum permissible difference is exceeded. In particular, a result of a subprocess of the actual process is compared with a result of a subprocess of a target process. Additionally or alternatively, a parameter of a subprocess of a target process is compared with a parameter of a subprocess of an actual process. Preferably, monitoring covers subprocesses at different hierarchical levels.For example, adherence to a speed is monitored by ensuring that the difference between two consecutive position values ​​of a position signal does not exceed a maximum permissible value. Specifically, a deviation between the monitored information of the target process and the actual process is compared against a limit value that may not be exceeded, or only a limited number of times, particularly during a defined period. This allows for flexible configuration of monitoring parameters.

[0029] In a preferred embodiment, a process comprises several sequential and / or concurrent subprocesses. For example, a robot performs a movement, and simultaneously, a gripper located on the robot's tool opens. A subprocess can be an unconstrained movement, in particular a movement of a manipulator of the manipulator arrangement in free space or in a medium. Additionally or alternatively, a subprocess can include environmental contact. In particular, environmental contact of a manipulator of the manipulator device with a physical object and / or environmental contact of a tool of such a manipulator with a physical object. Advantageously, this allows monitoring to be directed at specific phases of the actual process.

[0030] According to the invention, monitoring is model-based. For example, speed monitoring is based on a derivation of the robot's position signals and / or on a state-space model. A model within the meaning of the invention is preferably a model of an actual process or a subprocess of an actual process. A model can also represent an actual process or one or more subprocesses of a target process. Accordingly, monitoring can be directed at one or more results of a model. Additionally or alternatively, monitoring can be directed at one or more parameters of a model. Preferably, a model comprises a state observer and / or a Kalman filter. Additionally or alternatively, a model can represent a workspace of one or more manipulators of the manipulator arrangement. This allows workspace boundaries to be monitored depending on the workspace represented.According to the invention, a model transforms a reliably detected quantity into a quantity that is not reliably detected. This allows monitoring of a state that is not reliably detected. Advantageously, a model can be used to monitor the state of a robot without observing it through direct measurement.

[0031] According to the implementation described here, monitoring is configured by a user. For example, monitoring for a robot is configured by an operator of that robot. A user can, in particular, be an operator of the manipulator arrangement. The user can configure the monitoring at the same user interface where they also define the virtual target process. Additionally or alternatively, a user can be a person who issues instructions to the manipulator arrangement via a communication interface, in particular a network, preferably via the internet. Advantageously, this allows monitoring to be modified based on new assessments by a human operator. Additionally or alternatively, monitoring can be configured by the state of a device.Such a state can be, in particular, a state of a manipulator arrangement, a controller, or a device in the vicinity of the manipulator arrangement that interacts with the manipulator arrangement. Such predefined monitoring can, in particular, modify, extend, and / or replace a standard predefined monitoring system. Additionally or alternatively, an existing monitoring system can be modified qualitatively, in particular by adjusting a parameter, and / or structurally, in particular by adding new sub-monitoring elements. Advantageously, this allows for the automated modification of one or more monitoring systems while the robot is executing an actual process.

[0032] Following a first aspect of a preferred implementation, the specification of a target process and / or the specification of a monitoring procedure is executed offline, particularly in advance, and preferably only then is the execution of the actual process started. Advantageously, this allows for initial verification that a specified target process and / or a specified monitoring procedure meets all relevant requirements.

[0033] According to a second aspect of a preferred embodiment, the specification of a target process and / or the specification of a monitoring system is performed online. This can occur, in particular, during the execution of an actual process. For example, a maximum permissible speed value for a robot is reduced while it is in motion. Preferably, the online modification of the monitoring system for one subprocess is possible while another subprocess is being executed. In particular, it is also possible to modify the monitoring system for one subprocess while that subprocess is being executed. Preferably, the execution of the actual process is only possible after the execution has been enabled in a previous step, in particular by an enable signal. Advantageously, this allows changes to be made to one or more monitoring systems after the actual process has been started.

[0034] In a preferred embodiment, a monitoring setting can be modified by authorized personnel. For example, a specially trained user configures monitoring settings that other users are not permitted to configure. In particular, the number and scope of setting options are organized into different classes. Preferably, these classes distinguish between settings configured by "Operator," "Expert," and "Administrator." "Operators" can only specify a virtual target process within predefined parameters, especially parameters of the safety functions. Experts can additionally select or deselect specific safety functions. Preferably, only an Administrator can modify parameters of safety functions, such as working area, speed, and / or force limits, and make a complete selection of which safety functions should be used.These classes preferably apply not only to users, but also to devices through which virtual target processes and / or monitoring can be defined. This advantageously ensures that only authorized persons and / or devices may exercise complete control over the safety functions.

[0035] In a preferred embodiment, one or more monitoring parameters are reliably specified. For example, speed monitoring is redundantly specified using two channels. A reliable specification is, in particular, one that complies with a common safety standard for manipulator arrangements, preferably EN 13849 and / or IEC 61508. According to a first aspect of this embodiment, monitoring is reliably specified via a suitable interface, in particular a safe user interface. This can be a user interface specifically designed ergonomically to prevent input errors. Additionally or alternatively, a reliable monitoring specification can be communicated via a suitable network, in particular via EtherCAT, preferably with the safety-related functionality FsoE. This advantageously prevents errors during the configuration of monitoring parameters.A second aspect of this design involves creating a monitoring system within a secure structure. Such a monitoring system, in particular, incorporates one or more structural or temporal redundancies. Additionally or alternatively, a secure monitoring system can include cross-comparisons between multiple independent monitoring systems that focus on an actual process or a sub-process of that actual process. This preferably results in higher reliability of the monitoring system.

[0036] The preferred training courses can be combined to their advantage.

[0037] Further advantages and features will become apparent from the dependent claims and the exemplary embodiments. These are shown, in part schematically: Fig. 1: An embodiment of the method according to the invention; Fig. 2: Monitoring of various sub-processes according to an embodiment of the method according to the invention; Fig. 3: Monitoring of various sub-processes according to an embodiment of the method according to the invention.

[0038] Fig. 1 Figure 1 illustrates the method according to the invention. In a first step, a virtual target trajectory P_v is specified. In a second step, a monitoring system is automatically generated based on the virtual target trajectory. In a third step, the virtual target trajectory is implemented by a manipulator, and a real actual trajectory is followed. The monitoring is then carried out according to the specifications, ensuring that the actual trajectory is monitored.

[0039] Fig. 2 Figures 5 and 6 show automatically generated monitoring data for a hierarchically structured subprocess. Starting with a movement x(t), interpolation setpoints are generated. These are monitored and compared with the initially specified movement. Interpolation axis values ​​are determined from the interpolated Cartesian values ​​via a kinematic transformation. Based on these interpolated axis values, a monitor registers whether the maximum working space limits are exceeded. For this purpose, the kinematic model is analyzed. Finally, the interpolation axis values ​​are communicated to a robot 4 for execution.

[0040] Fig. 3Figures 11 and 12 show automatically generated monitoring data from a phased subprocess. First, a manipulator performs a point-to-point (PTP) movement. Then, a linear (LIN) movement is performed. This LIN movement is monitored, with maximum speeds being checked. In a third phase, the robot performs a gripping movement. This gripping movement is also monitored. The gripping movement monitoring system checks whether the gripper exceeds the maximum permissible force values ​​during gripping.

[0041] In a non-illustrated implementation, a target process P_v for human-robot interaction is defined via a user interface. In addition to the pre-programmed process plan, the user interface also displays to the operator which parameters or states can be used for user-configurable monitoring of this human-robot interaction. These parameters or states must be acquired using safe technology and are highlighted in yellow in the user interface and enabled for monitoring programming. The monitoring parameters S are defined by the user via the same user interface as the virtual target process. The configuration is done in an IEC 61131 language, e.g., as a Sequential Function Chart and / or a Function Block Diagram.First, a user, authenticated with operator status at the controller, configures a virtual target process and specifies that it is to be executed within a human-robot interaction. Based on this predefined virtual target process, the controller generates the corresponding interpolation values ​​for execution by the robot. The controller also generates the necessary monitoring parameters for process execution. In this case, the controller monitors the maximum force that can be applied by the gripper, which is limited to a maximum of 10 N by default. Additionally, the controller generates a collision detection system. It utilizes safe torque sensors and safe position sensors for this purpose. A collision observer, which includes models of the robot and, in particular, its environment, is used for collision detection.After the specification and generation of the interpolation values ​​and monitoring parameters are completed, the robot executes the process, and the resulting actual process is monitored by the automatically generated monitoring parameters. During execution, the process is modified by another user. This user identifies themselves as a safety administrator via the user interface. They modify the maximum applicable force to 20 N and additionally activate speed monitoring, setting the maximum speed to 20 cm / s. The affected safety functions are automatically updated and applied by the controller.

Claims

1. A method for controlling a manipulator system comprising at least one manipulator (4), in particular a robot, which includes a controller, comprising: a step A (S10) of specifying a virtual target process (P_v); a step B (S30) of executing an actual real-time process (P) by the manipulator assembly based on the virtual target process (P_v); a step C (S40) of monitoring the actual real-time process (P); and a step D (S20) of specifying at least one monitoring function (S; 5, 6, 11, 12) of the actual real-time process (P) by the controller based on the virtual target process (P_v), wherein the at least one monitoring function (S; 5, 6, 11, 12) is specified based on a model; wherein the manipulator assembly is transitioned to a safe state if the at least one monitoring detects a malfunction; wherein the model transforms a safely detected variable into a variable that is not safely detected; wherein the at least one monitoring is directed at one or more results of the model; wherein the at least one monitoring is defined based on a detection of a state of the manipulator assembly; wherein this state indicates the presence of safe sensor technology and / or safe actuator technology.

2. The method according to claim 1, characterized in that monitoring (S; 5, 6, 11, 12) is performed based on a state - of the controller, - of a tool of a manipulator of the manipulator assembly, - of a workpiece to be manipulated, and / or - a device that interacts with the manipulator assembly, is specified.

3. Method according to one of the preceding claims, characterized in that a process (P_v, P) and / or a monitoring (S; 5, 6, 11, 12) comprises several hierarchical subprocesses, in particular a path planning and / or a kinematic transformation.

4. A method according to any of the preceding claims, characterized in that a process (P_v, P) comprises sequential and / or parallel subprocesses, in particular an unconstrained movement or an environmental contact.

5. A method according to claim 3 or 4, characterized in that the control system specifies at least one monitoring (S; 5, 6, 11, 12) of a subprocess of the actual real-time process (P) based on a subprocess of the virtual target process (P_v).

6. A method according to one of the preceding claims, characterized in that monitoring (S; 5, 6, 11, 12) is specified by - a user, - a state of the manipulator assembly, - a state of the controller, and / or - a state of a device from the environment of the manipulator assembly that interacts with the manipulator assembly.

7. A method according to any of the preceding claims, characterized in that step A (S10) and / or step D (S20) is performed offline, in particular in advance, and / or online, in particular during step B (S30).

8. A method according to any of the preceding claims, characterized in that the specification of the monitoring (S; 5, 6, 11, 12) can be modified with authorization.

9. A method according to any of the preceding claims, characterized in that at least one monitoring function (S; 5, 6, 11, 12) is securely specified.

10. A method according to any of the preceding claims, characterized in that step B (S30) is performed only after step D (S20) has been completed.

11. A method according to any of the preceding claims, characterized in that the at least one monitoring (S; 5, 6, 11, 12) of the actual real-time process (P) is automatically generated by the controller based on the virtual target process (P_v).

12. A controller for a manipulator, in particular a robot, configured to perform a method according to any of the preceding claims.

13. A computer program that executes a method according to any of claims 1 through 11 when running in a controller according to claim 12.

14. A computer program product comprising program code stored on a machine-readable medium and comprising a computer program according to claim 13.