Method for calculating the quality of a robot relief device of a robot system

Abstract

In a method for calculating the quality of a robot relief device of a robot system (1), wherein the robot system (1) has at least one robot device (2) with at least one robot element (4, 6, 8) arranged to be movable on at least one robot joint and at least one actuator (10-13, 15) for moving the at least one robot element (4, 6, 8), wherein at least one relief device (3) is provided for relieving the robot device (2) when using the robot system (1) in the gravitational field of the earth, wherein at least one force application element (30) is connected to the robot element (4, 6, 8) at at least one coupling point and at least one delimbing force is applied to the robot element (4, 6, 8), which at least partially compensates for the gravitational force acting on the robot element (4, 6, 8), wherein at least one torque measuring device measures the torques occurring in the at least one robot joint, wherein a robot system simulation device is provided which simulates the robot system in a virtual environment, it is provided that a robot system simulation device is provided, which simulates the robot system in a virtual environment, wherein the quality of the relief of the robot device (2) is determined by means of the relief device (3), wherein the torques measured with the at least one torque measuring device are compared by a control device with torques simulated by means of the robot system simulation device and a quality value is determined which reflects the quality of the relief.

Description

[0001] The invention relates to a method for calculating the quality of a robot relief device of a robot system according to claim 1 and a robot system for calculating the quality of a robot relief device according to claim 9.

[0002] Robotic devices are known that are manufactured specifically for use in space. Space robotic devices are designed for conditions in space. Since no gravitational forces act on the space robotic device in space, a large portion of the forces required due to gravity can be neglected in the design of the space robotic device. This allows the robot joints and / or actuators to be smaller, lighter, and more energy-efficient.

[0003] However, the robot equipment will also be operated on Earth, for example to test or improve it. To do this, the robot equipment must be supported, as otherwise the robot joints would be subjected to excessive strain or the actuators would be unable to move the robot equipment. For this purpose, load-bearing devices exist that support the robot equipment on Earth. This can be done, for example, with helium balloons or planar, active or passive support tables. Helium balloons, which can have a diameter of several meters depending on the payload, contribute to load relief through their buoyancy. These are mounted on the robot equipment at the designated points and pull the robot equipment upwards at this point with a constant force. Planar, movable support tables can, for example, glide over smooth floors and support the robot joints of the robot equipment.However, with this method, the robotic devices can only perform planar movements.

[0004] Robot systems are known which each have at least one robot device with at least one robot element arranged to be movable on at least one robot joint and at least one actuator for moving the at least one robot element, wherein at least one relief device is provided for relieving the robot device when the robot system is used in the gravitational field of the earth, wherein at least one force application element is connected to the robot element at at least one coupling point and at least one relief force is applied to the robot element which at least partially compensates for the gravitational force acting on the robot element, wherein at least one torque measuring device measures the torques occurring in the at least one robot joint.

[0005] DE102023108354A1 discloses a device for simulating the weightless dynamics of a freely suspended object in space under the influence of gravity. The device comprises a robot with multiple drive elements that support the object against the gravitational force either directly or via a bearing arrangement. The robot is designed to move the object translationally along three orthogonal spatial axes and rotationally around one spatial axis in the direction of the gravitational force. A sensor detects external forces and / or resulting movements on the object and transmits them to a control device, which then controls the drive elements to represent the weightless dynamics. The bearing is gimbal-mounted, allowing the object to move in multiple degrees of freedom.The object or bearing is suspended from the robot via a tensile force-transmitting bracket, whereby the bracket forms a vertical suspension axis.

[0006] DE102023128612A1 describes a robot system with a space robot device comprising at least one movable robot element and an actuator for moving this element. A support device serves to partially compensate for the effects of gravity during operation on Earth. This support device is designed as a cable robot system containing at least two cable elements connected to a force application element. Each cable element is connected to a motor that can move the cable element, allowing the direction and magnitude of the force acting on the robot element to be specifically adjusted.

[0007] DE102017215642B3 relates to a method for controlling a robot comprising a control unit and a controlled robot arm with multiple links and joints. A force compensation device is assigned to the robot arm, which is connected to the arm via a mechanical coupling to introduce a compensation force generated by the device into the robot arm. This compensation force is controlled using a mathematical model of the force compensation device that takes its physical properties into account.

[0008] EP3926421A1 discloses a computer-aided method for the multi-domain simulation of multiple technical target variables of a production machine. The simulation is performed simultaneously in at least two physical domains—in particular, the mechanical and electronic signal domains. The production machine comprises a manipulator, a drive device, and a control device. The method involves providing a first model component for mechanical properties in a first development environment and a second model component for electronic properties in a second development environment. Both model components are integrated into a common simulation application to simulate technical target variables based on different parameter sets. The simulation is performed multiple times with different parameter combinations, resulting in a specific result data set in each case.

[0009] AT11337U1 relates to a method and device for the sequential, robot-assisted gripping and moving of objects from a defined spatial area. The device comprises an optical detection unit, a memory for storing object models and gripping points, an identification unit for determining the position of the objects, and a robot-controlled gripper for the targeted transport of the objects to a target location. For optimization, a simulation device is provided, which simulates and evaluates the upcoming gripping and moving process. Based on this simulation, a decision is made as to whether the gripping process should be carried out with the planned parameters or whether alternative gripping points or other objects should be given priority.

[0010] CA2521554A1 describes a system for simulating the behavior of a target robot with respect to a payload and a working environment. The system comprises a real-time simulator for capturing the dynamics of the target robot, a model of the payload and the working environment, and an emulating robot that interacts with this environment. This robot is controlled by the simulator via a control loop, so that it simulates the dynamic behavior of the target robot in real time. In particular, the impedance of the emulated robot is adapted to that of the target robot to ensure a realistic simulation.

[0011] The object of the present invention is to enable an optimization and / or evaluation of the relief system.

[0012] The features of claims 1 and 9 serve to solve this problem.

[0013] The invention advantageously provides that the quality of the relief of the robot device is determined by means of the relief device. The torques measured by the at least one torque measuring device are compared by a control device with torques simulated by the robot system simulation device, and a quality value is determined that reflects the quality of the relief. Relief of the robot device refers to the relief of the robot device by means of the relief device.

[0014] The present invention has the advantage that the quality of the relief of the robot device can be assessed and compared, and thus the relief system can be optimized.

[0015] The torques measured with the at least one torque measuring device can also be referred to as measured robot joint torques.

[0016] The torques simulated by the robot system simulation device can also be referred to as simulated robot joint torques or calculated robot joint torques.

[0017] The control device can determine the quality value using a weighted least-square-root method.

[0018] The least square root method, also known as the least squares method, is a mathematical procedure used to find the best estimates for a model's parameters. It minimizes the sum of the squares of the deviations (residuals) between the measured values ​​and the values ​​predicted by a model.

[0019] In the present invention, the measured values ​​are the torques measured in the at least one robot joint by means of the at least one torque measuring device. In the present invention, the values ​​predicted by a model are the torques simulated by the robot system simulation device.

[0020] The weighted least squares root method, also known as weighted least squares (WLS), is an extension of the least squares method. It assigns different weights to the deviations (residuals) between the measured values ​​and the values ​​predicted by a model to account for the fact that some observations may be more reliable or important than others.

[0021] The quality value can be a single value.

[0022] The quality value can be defined such that the lower the quality value, the better the relief quality. This means that if the measured and simulated values ​​are close to each other, the difference between the two values ​​is small, resulting in a low quality value, and thus the relief quality can be rated as good.

[0023] The robot system simulation facility can take into account physical laws and properties, such as the movement, force and dynamics of the robot arm, for the simulation.

[0024] The control device may be the control device of the relief system.

[0025] The quality value can be recalculated at each time step.

[0026] The length of each time step depends on the dynamics and size of the robot system and can, for example, range from 0.2 ms to 100 ms. A preferred range is 0.5 ms to 5 ms, particularly preferably 1 ms.

[0027] The quality value τ vgl can be calculated using the following formula: τvgl=1aτ¯TWτ¯ where α: Number of considered robot arm joint torques τ: torques to be considered as vector representation, where the rows of the vector contain the values ​​of the torques, where τ = |τ mess - τ simulation |, where τ mess the measured robot arm joint torques and τ simulation. the simulated robot arm joint torques are W: Weighting factors as a diagonal matrix representation, in which the diagonal elements contain the weighting factors for the respective torques and all other matrix elements are zero.

[0028] According to the present invention, a robot system for calculating the quality of a robot relief device can also be provided, with at least one robot device with at least one robot element arranged to be movable on at least one robot joint and at least one actuator for moving the at least one robot element, at least one relief device for relieving the robot device when using the robot system in the gravitational field of the Earth, wherein at least one force application element is connected to the robot element at at least one coupling point and at least one relief force can be applied to the robot element, which at least partially compensates for the gravitational force acting on the robot element, wherein at least one torque measuring device is provided for measuring the torques occurring in the at least one robot joint, wherein a robot system simulation device is provided which simulates the robot system in a virtual environment, wherein a control device is provided which is designed to determine the quality of the relief of the robot device by means of the relief device, wherein the control device is designed to compare the torques measured with the at least one torque measuring device with the torques simulated by means of the robot system simulation device and to determine a quality value which reflects the quality of the relief.

[0029] The control device can be designed to determine the quality value using a weighted least-square-root method.

[0030] The robot system simulation device can be designed to take into account physical laws and properties, such as the movement, force and dynamics of the robot arm for the simulation.

[0031] The control device may be the control device of the relief system.

[0032] The control device can be designed to determine the quality value τ vgl using the following formula: τvgl=1aτ¯TWτ¯ where α: Number of considered robot arm joint torques τ: torques to be considered as vector representation, where the rows of the vector contain the values ​​of the torques, where τ = |τ mess - τ simulation |, where τ mess the measured robot arm joint torques and τ simulation the simulated robot arm joint torques are W: Weighting factors as a diagonal matrix representation, in which the diagonal elements contain the weighting factors for the respective torques and all other matrix elements are zero.

[0033] In the following, an embodiment of the present invention is explained in more detail with reference to the drawings.

[0034] They show schematically Fig. 1 the robot system, Fig. 2 an excerpt from Fig. 1, which shows the force application element, Fig. 3 Robot device, the control device and robot system simulation device.

[0035] In Fig. 1 shows a robot system 1. The robot system 1 has a robot device 2. The robot device 2 is preferably a space robot device. The robot device 2 has at least one robot element 4 movably arranged on at least one robot joint 12. In the present exemplary embodiment, at least three movable robot elements 6, 4, and 8 are provided. The at least one movable robot element 4 can be moved with at least one actuator 13. In the present exemplary embodiment, an actuator 15 is provided which can move the robot element 6. Furthermore, an actuator 13 is provided which can move the robot element 4, and an actuator 11 is provided which can move the robot element 8. Furthermore, robot joints 14, 12, and 10 are provided, around which the respective robot elements 6, 4, and 8 can rotate.Furthermore, at least one torque measuring device 72, 74, 76 is shown, which measures the torques occurring in at least one robot joint 14, 12, and 10. In the illustrated embodiment, a torque measuring device 72, 74, 76 is arranged at each robot joint 14, 12, and 10.

[0036] In the present embodiment, the robot device 2 is preferably a robot arm. Furthermore, the robot device is preferably mounted on a spatially fixed object at location 16. Alternatively, the robot device can also be attached to a movable base.

[0037] The robot system 1 has a relief device 3 which can support the robot device 2 when the robot device is used in the earth's gravitational field. The relief device 3 has at least one force application element 30 which is connected to the at least one robot element 4 at at least one coupling point and to which at least one force can be applied to the at least one robot element 4, which force at least partially compensates for the gravitational force or gravity acting on the one robot element 4. This means that at least a portion of the force exerted on the robot element 4 via the force application element 30 acts against the gravitational force or gravity. By applying the force and partially compensating for the gravitational force or gravity, the robot device 2 is supported or relieved. The robot device 2 should be supported or relieved at least as much asbe relieved so that the actuators 10, 12 and 15 can move the robot elements 6, 4 and 8.

[0038] The illustrated relief device 3 is a cable robot system that has at least two cable elements, in the present embodiment four cable elements 18, 20, 22, 24, which are connected to the force application element 30. In the illustrated embodiment, four cable elements 18, 20, 22, and 24 are provided, and each cable element 18, 20, 22, 24 is connected to at least one motor 38, 36, 34, 32, which can move the respective cable element 18, 20, 22, 24. By actuating the respective motor 38, 36, 34, 32, for example, the respective cable element 18, 20, 22, 24 can be rolled up, thus moving the respective cable element 18, 20, 22, 24. At point 48, the four cable elements 18, 20, 22, 24 are connected to a force application cable 26. The force application cable 26 is connected to a force application element 30.Thus, in the illustrated embodiment, the cable elements 18, 20, 22, 24 are indirectly connected to the force application element 30.

[0039] Depending on how tightly the individual cable elements 18, 20, 22, 24 are wound, a force is exerted on the force application element 30 and thus on the robot element 4. By adjusting the motors and moving the cable elements 18, 20, 22, 24, the magnitude and direction of the force acting on the force application element 30 and thus on at least one robot element 4 can be adjusted. The cable elements 18, 20, 22, 24 are deflected via deflection elements 41, 43, 45, and 47. The deflection elements 41, 43, 45, and 47 are preferably arranged above the robot element 4.

[0040] At least one force measuring device 28 can be provided to measure the magnitude of the unloading force. The force measuring device 28 can measure the magnitude of the force acting in the force application cable and thus corresponds to the magnitude of the force acting on the robot element 4 and thus relieving it.

[0041] Additionally or alternatively, sensor devices 42, 44, 40, and 46 may also be provided to measure the forces in the cable elements 18, 20, 22, and 24. The total force measurable with the second sensor device 29 may also alternatively be calculated using the forces measured by the sensor devices 42, 44, 40, and 46.

[0042] In an alternative embodiment, the force application cable 26 may be omitted and the cable elements 18, 20, 22 and 24 may be connected directly to the force application element 30.

[0043] The invention is not limited to four cable elements 18, 20, 22, and 24, but can also be implemented with more or fewer cable elements. However, at least two cable elements should be provided so that the direction and magnitude of the force can be varied.

[0044] Furthermore, the coordinate system with the spatial directions x, y, and z is shown. This is the coordinate system in the space in which the robot device 2 is arranged. The robot device 2 can move within this space.

[0045] In Fig. 2 is an excerpt from the Fig. 1, in which the force application element 30 is shown in more detail. The force application element 30 is rotatable about at least a first axis 50 and at least a second axis 52. The first and second axes 52 are preferably substantially orthogonal to one another. Depending on where the robot element 4 is located and how the motors 38, 36, 34, 32 were actuated and thus the cable elements 18, 20, 22, 24 were moved, the force application cable 26 has a different position relative to the robot element 4. The force application element 30 orients itself accordingly.

[0046] The force application element 30 is thus moved passively, depending on the position of the cable elements and the robot element 4. The first axis 50 of the force application element 30 is preferably arranged coaxially with the axis of the robot element 4. At least one first angle measuring device A1 and one second angle measuring device A2 can be provided, which can detect the respective angle about the first and second axes 50, 52 between the force application cable 26 and the robot device 2. This allows the position of the force application cable 26 relative to the robot element 4 to be determined in order to determine the direction in which the applied force acts on the robot element 4 or the robot device 2.

[0047] In Fig.3 shows the robot device 2, the control device 64, and the robot system simulation device 62. The robot system simulation device 62 simulates the robot system in a virtual environment. The quality of the load relief of the robot device 2 can be determined, wherein the torques τ measured with the at least one torque measuring device 72, 74, 76 mess by the control device 64 with torques τ simulated by the robot system simulation device 62 simulation be compared and a quality value τ vgl which reflects the quality of the relief.

[0048] The robot system simulation device 62 calculates the simulated robot joint torques τ simulation. The robot system simulation device 62 can use measured joint angles 60 of the robot device 2 and the desired relief force 70 from the control device 64. From this, the robot system simulation device 62 calculates the simulated torques 68 in a virtual robot device. The number of simulated torques τ simulation correspond to the number of robot joints of the robot device.

[0049] The respective measured robot joint torques τ messare measured on robot device 2. These are measured with the respective torque measuring device 72, 74, 76, which is preferably arranged on the respective robot joint 10, 12, 14. The number of values ​​corresponds to a maximum of the number of robot joints 10, 12, 14 in robot device 2. The robot joint torques are composed as follows, whereby only three values ​​are considered in this example and can be expanded for additional robot joints 10, 12, 14: τmess=[τmess,1τmess,2τmess,3]

[0050] The control device 64 calculates the quality value τ vgl from the torques to be considered. The torques to be considered are calculated from the difference between the measured torques τ mess and the simulated torques τ simulation , where the simulated torques τ simulation the respective torques simulated for the respective robot joints.

[0051] The calculation of the quality value τ vgl This is preferably done using the weighted root-mean-square method:

[0052] The quality value τ vgl can be calculated using the following formula: τvgl=1aτ¯TWτ¯ α: Number of considered robot joint torques τ: torques to be considered as vector representation, where the rows of the vector contain the values ​​of the torques, where τ= |τ mess - τ simulation |, where τ mess the measured robot joint torques and τ simulation . the simulated robot joint torques are W: Weighting factors as a diagonal matrix representation, in which the diagonal elements contain the weighting factors for the respective torques and all other matrix elements are zero

[0053] The weighting factors are determined by analyzing the robot system in question. This analysis may reveal, for example, that a deviation in the x- and y-direction has a greater impact than a deviation in the z-direction. The weighting matrix would then be adjusted accordingly.

[0054] The torques τ to be considered werden calculated in the control device 64 from the robot joint torques and from the simulated robot joint torques: τ¯=|τmeasurement−τsimulation|

[0055] Here τ mess the measured robot joint torques. These are measured in the robot setup. The vector τ simulation represents the simulated robot joint torques from the robot system simulation device 62. Both are in vector representation, with the rows of the vector containing the values ​​of the torques.

[0056] The simulated torques can be composed as follows, whereby in this example only conservative physical laws and properties are taken into account and can be extended accordingly, for example, with friction terms: M(q)q¨+C(q,q˙)q˙+g(q)=τg+JCT(q)Γc

[0057] Here, q is the robot arm joint angle in vector representation, and q̇ and q̈ are the velocity and acceleration of the robot joint angles. The masses of the robot are represented in matrix M, and the components of the Coriolis forces are represented in matrix C. The joint forces due to gravity are represented in g. The Jacobian matrix JCT contains the kinematic transformation from the connection point of the unloading system to the joint angle. The desired unloading force is vector Γc.

[0058] The robot system simulation device 62 can also be deactivated for a simplified quality value calculation. When the robot system simulation device is deactivated, the simulated robot joint torques calculated are always zero. 1 robot system 2 Robot setup 3 Relief device 4, 6, 8 robot element 10, 12, 14 Robot joint 11, 13, 15 Actuator 16, 48 place 18, 20, 22, 24 rope element 26 Force application rope 28 Force measuring device 29 second sensor device 30 Force application element 32, 34, 36, 38 engine 40, 42, 44, 46 Sensor devices 41, 43, 45, 47 deflection elements 50 first axis 52 second axis 60 robot element joint angles 62 Robot system simulation facility 64 Control device τmess measured robot joint torques τ simulation simulated torques 70 desired relief force τ vgl Quality value 72, 74, 76 Torque measuring device

Claims

[1] Method for calculating the quality of a robot relief device of a robot system (1), wherein the robot system (1) has at least one robot device (2) with at least one robot element (4, 6, 8) arranged to be movable on at least one robot joint and at least one actuator (10-13, 15) for moving the at least one robot element (4, 6, 8), wherein at least one relief device (3) is provided for relieving the robot device (2) when using the robot system (1) in the gravitational field of the earth, wherein at least one force application element (30) is connected to the robot element (4, 6, 8) at at least one coupling point and at least one delimbing force is applied to the robot element (4, 6, 8), which at least partially compensates for the gravitational force acting on the robot element (4, 6, 8), wherein at least one torque measuring device measures the torques occurring in the at least one robot joint, characterized by , that a robot system simulation device is provided which simulates the robot system in a virtual environment, wherein the quality of the relief of the robot device (2) is determined by means of the relief device (3), wherein the torques measured with the at least one torque measuring device are compared by a control device with torques simulated by means of the robot system simulation device and a quality value is determined which reflects the quality of the relief. [2] Method according to claim 1, characterized by that the control device (204) determines the quality value by means of a weighted least-square-root method. [3] Method according to claim 1 or 2, characterized by that the quality value (200) is a single value. [4] Method according to claim 3, characterized by that the quality value is defined in such a way that the lower the quality value, the better the quality of the relief. [5] Method according to one of claims 1 to 4, characterized by that the robot system simulation facility takes into account physical laws and properties, such as the movement, force and dynamics of the robot arm. [6] Method according to one of claims 1 to 5, characterized by that the control device is the control device of the relief system. [7] Method according to one of claims 1 to 6, characterized by that the quality value is recalculated in each time step. [8] Method according to one of claims 1 to 7, characterized by that the quality value τ vgl is calculated using the following formula: τvgl=1aτ¯TWτ¯ α: Number of considered robot joint torques τ: torques to be considered as vector representation, where the rows of the vector contain the values ​​of the torques, where τ = |τ mess - τ simulation |, where τ mess the measured robot joint torques and τ simulation the simulated robot joint torques are W: Weighting factors as a diagonal matrix representation, in which the diagonal elements contain the weighting factors for the respective torques and all other matrix elements are zero [9] Robot system (1) for calculating the quality of a robot relief device, with at least one robot device (2) with at least one robot element (4, 6, 8) arranged to be movable on at least one robot joint and at least one actuator (10-13, 15) for moving the at least one robot element (4, 6, 8), at least one relief device (3) for relieving the robot device (2) when using the robot system (1) in the gravitational field of the earth, wherein at least one force application element (30) is connected to the robot element (4, 6, 8) at at least one coupling point and at least one relief force can be applied to the robot element (4, 6, 8), which at least partially compensates for the gravitational force acting on the robot element (4, 6, 8), wherein at least one torque measuring device is provided for measuring the torques occurring in the at least one robot joint, characterized by , that a robot system simulation device is provided which simulates the robot system in a virtual environment, wherein a control device (204) is provided which is designed to determine the quality of the relief of the robot device (2) by means of the relief device (3), wherein the control device (204) is designed to compare the torques measured with the at least one torque measuring device with the torques simulated by means of the robot system simulation device and to determine a quality value which reflects the quality of the relief. [10] Robot system (1) according to claim 9, characterized by that the control device (204) is designed to determine the quality value by means of a weighted least-square-root method. [11] Robot system (1) according to claim 9 or 10, characterized bythat the robot system simulation device is designed to take physical laws and properties, such as the movement, force and dynamics of the robot arm, into account for the simulation. [12] Robot system (1) according to one of claims 9 to 11, characterized by that the control device is the control device of the relief system. [13] Robot system (1) according to one of claims 9 to 12, characterized by that the control device (204) is designed to determine the quality value τ vgl using the following formula: τvgl=1aτ¯TWτ¯ α: Number of considered robot joint torques τ: torques to be considered as vector representation, where the rows of the vector contain the values ​​of the torques, where τ = |τ mess - τ simulation |, where τ mess the measured robot joint torques and τ simulationthe simulated robot joint torques are W: Weighting factors as a diagonal matrix representation, in which the diagonal elements contain the weighting factors for the respective torques and all other matrix elements are zero.

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