Robotic arm calibration

Abstract

The invention relates to a method for calibrating a robot arm by means of a measuring device having a first and a calibration element fixed to the robot arm, which calibration element fixed to the robot arm can be moved relative to the first calibration element by adjusting a joint of the robot arm, when the calibration element fixed on the robot arm is displaced relative to the first calibration element in the first feed direction, the calibration element fixed on the robot arm is guided from different starting positions to the same defined first end position through the first calibration element. The method comprises the following steps: positioning (S10) a calibration element fixed to the robotic arm in one of the starting positions relative to a first calibration element; moving (S20), by means of the robot arm, the calibration element fixed to the robot arm relative to the first calibration element in a force-adjusted manner in a first feed direction, the calibration element fixed to the robot arm being guided by the first calibration element into an end position in which the robot has a calibration position; detecting (S30) a joint pose of the robotic arm in the calibration pose; and calibrating (S110) the robotic arm based on the joint pose.

Description

Technical Field

[0001] The invention relates to a method for calibrating a robot arm and to a system, a computer program or a computer program product for performing the method described herein. Summary of the invention

[0002] An object of the present invention is to improve the calibration of a robot arm.

[0003] The object of the invention is achieved by a method having the features of claim 1. Claims 9 and 10 protect a system or a computer program or a computer program product for carrying out the method described here. Preferred developments are given by the dependent claims.

[0004] According to one embodiment of the invention, the robot arm has a plurality of, preferably at least three, in particular at least six, in one embodiment at least seven, joints or (motion) axes, in one embodiment being revolute joints.

[0005] According to one embodiment of the invention, the measuring device has at least two calibration elements, each of which can be designed in one piece or in multiple parts.

[0006] In one embodiment, one of the calibration elements is a calibration element which is fixed to the robot arm and is arranged fixedly (ortfest) in an extended manner, (non-destructively) removably in one embodiment, (non-destructively or) non-removably or permanently on the robot arm, preferably at the (distal) end of the robot arm or on a tool flange or end segment.

[0007] In one embodiment, the further calibration element is referred to as the first calibration element without loss of generality. In one embodiment, the further calibration element is arranged fixedly relative to a stationary or mobile environment and / or a base of the robot arm, in one embodiment (non-destructively) removably, in another embodiment (non-non-destructively or) non-removably or permanently on the environment or the robot arm base.

[0008] The calibration element fixed to the robot arm can be moved relative to the first calibration element by adjusting the joint of the robot arm, wherein the first calibration element and the calibration element fixed to the robot arm are constructed so that when the calibration element fixed to the robot arm is moved relative to the first calibration element in a spatial direction (referred to herein without loss of generality as the first feed direction), the calibration element fixed to the robot arm can be (finally) (forced) guided from different starting positions (referred to herein without loss of generality as the first starting position) through the first calibration element, preferably mechanically or form-fittingly, to the same, in particular clearly defined, preferably single or unique end position (referred to herein without loss of generality as the first end position). A simple and preferred example is a funnel for guiding a ball: if the ball moves relative to the funnel into the funnel, the ball contacts the funnel surface. When then moving further into the funnel, the funnel guides the ball inward to a defined end position. This can preferably be achieved by a ball fixed to the robot arm or guided, but of course it can also be achieved by moving the funnel fixed to the robot arm relative to the ball fixed to the environment.

[0009] According to one embodiment of the present invention, a method for calibrating a robot arm by means of a measuring device comprises the following steps:

[0010] - positioning, by means of the robot arm, a calibration element fixed to the robot arm relative to the first calibration element in one of the first starting positions;

[0011] - by means of the robot arm, a calibration element fastened to the robot arm is moved relative to the first calibration element in a first feed direction in a force-controlled manner, preferably by impedance control of the robot arm, wherein during this (force-controlled) movement, the calibration element fastened to the robot arm is preferably mechanically or form-fittingly (forced) guided by the first calibration element into a first end position, and the robot has a calibration posture in the first end position, which calibration posture is referred to herein without loss of generality as the first calibration posture;

[0012] - detecting the pose of the joints of the robot arm in a first calibration pose (referred to herein as the first pose without loss of generality), in one embodiment by means of sensors on the joints; and

[0013] - Calibrate the robot arm based on a first joint posture, in particular based on the first joint posture and a known, preferably predetermined and / or measured first end position, wherein, in one embodiment, the first end position is known, preferably predetermined and / or measured relative to the robot arm, in particular its base and / or relative to the environment of the robot arm, in particular a base of a measuring device.

[0014] In one embodiment, by moving a calibration element fixed to the robot arm in a force-adjustable, in one embodiment, impedance-adjustable manner by means of the robot arm, in combination with (forced) guidance of the first calibration element, the calibration element fixed to the robot arm can advantageously be arranged in a first end position reliably, precisely, quickly and / or along different guiding directions (e.g. horizontally or vertically upward, etc.) and used to calibrate the robot arm.

[0015] In one embodiment, the measuring device has at least one additional calibration element, which is referred to as a second calibration element without loss of generality. In one embodiment, this additional calibration element is also fixed in position relative to the environment and / or the base of the robot arm, in one embodiment it is (non-destructively) removable, in another embodiment it is (non-non-destructively or) non-removable or permanently arranged on the environment or the base of the robot arm.

[0016] The calibration element fixed to the robot arm can also be moved relative to the second calibration element by adjusting the joints of the robot arm, in particular after the robot arm is first arranged in a first end position and then moved away from the first end position, wherein the second calibration element and the calibration element fixed to the robot arm are constructed so that when the calibration element fixed to the robot arm is moved relative to the second calibration element along a spatial direction (referred to as the second feed direction in this article without loss of generality), the calibration element fixed to the robot arm is guided (forcibly) from different starting positions (referred to as the second starting position in this article without loss of generality) through the second calibration element, preferably mechanically or form-fittingly, to the same defined end position (referred to as the second end position in this article without loss of generality).

[0017] In an extension of this embodiment, the method has the same steps as described above with respect to the first calibration element with respect to the second calibration element, or has the following steps:

[0018] - positioning the calibration element fastened to the robot arm in one of the second starting positions relative to the second calibration element by means of the robot arm, preferably after first being moved by means of the robot arm into a first end position, detecting a first and optionally further poses of a joint of the robot arm in the first end position, and then moving the calibration element fastened to the robot arm again out of the first end position, in particular out of the first calibration element;

[0019] - by means of the robot arm, a calibration element fixed to the robot arm is moved in a force-controlled manner relative to a second calibration element in a second feed direction, wherein during this (force-controlled) movement, the calibration element fixed to the robot arm is (forcedly) guided by the second calibration element into a second end position, preferably mechanically or form-fittingly, and the robot has a calibration posture in this second end position, which calibration posture is referred to herein without loss of generality as the second calibration posture; and

[0020] - detecting a pose of the joint of the robot arm in a second calibration pose, which pose is referred to herein as a second pose without loss of generality;

[0021] The robot arm is calibrated based on the first joint posture and the second joint posture, preferably also based on a known, in one embodiment, predetermined and / or measured second end position, wherein in one embodiment the second end position is known, preferably predetermined and / or measured relative to the robot arm, in particular its base and / or relative to the environment of the robot arm, in particular the base of a measuring device.

[0022] In an extended embodiment, the measuring device has at least one additional calibration element, which is referred to as an additional second calibration element or a third calibration element without loss of generality. In one embodiment, this additional second calibration element is also fixed in position relative to the environment and / or the base of the robot arm, in one embodiment it is (non-destructively) removable, in another embodiment it is (non-non-destructively or) non-removable or permanently arranged on the robot arm base.

[0023] The calibration element fixed to the robot arm can also be moved relative to the third calibration element or the additional second calibration element by adjusting the joints of the robot arm, in particular after the robot arm is first arranged in a first end position, then moved away from the first end position, then arranged in the (first) second end position, and then moved away from the second end position, wherein the third calibration element or the additional second calibration element and the calibration element fixed to the robot arm are constructed so that when the calibration element fixed to the robot arm is moved relative to the third calibration element or the additional second calibration element along a spatial direction (referred to as the third feed direction or the additional second feed direction in this article without loss of generality), the calibration element fixed to the robot arm is guided (forced) from different starting positions (referred to as the third starting position or the additional second starting position in this article without loss of generality) through the third calibration element or the additional second calibration element, preferably mechanically or form-fittingly, to the same defined end position (referred to as the third end position or the additional second end position in this article without loss of generality).

[0024] In an extension of this embodiment, the method has the same steps as described above with respect to the first calibration element and the (one) second calibration element, or has the following steps:

[0025] - positioning the calibration element fixed to the robot arm relative to the third calibration element or the further second calibration element in one of the third starting position or the further second starting position by means of the robot arm, preferably first moving it by means of the robot arm to a first end position, detecting a first posture of the joints of the robot arm in the first end position and, if necessary, further postures, and then moving the calibration element fixed to the robot arm again out of the first end position, in particular out of the first calibration element, and then moving it by means of the robot arm to a (first) second end position, detecting a (first) second posture of the joints of the robot arm in the second end position and, if necessary, further postures, and then moving the calibration element fixed to the robot arm again out of the (first) second end position, in particular out of the (first) second calibration element;

[0026] - by means of the robot arm, a calibration element fixed to the robot arm is moved in a force-controlled manner relative to a third calibration element or a further second calibration element in a third feed direction or a further second feed direction, wherein, during this (force-controlled) movement, the calibration element fixed to the robot arm is preferably mechanically or form-fittingly (forced) guided by the third calibration element or the further second calibration element into a third end position or a further second end position, and the robot has a calibration posture in this end position, which calibration posture is referred to in this document without loss of generality as the third calibration posture or the further second calibration posture; and

[0027] - detecting a posture of a joint of the robot arm in a third calibration posture or an additional second calibration posture, which posture is referred to herein as the third posture or the additional second posture without loss of generality;

[0028] In which, the robot arm is calibrated based on the first joint posture, the (one) second joint posture and the third joint posture or another second joint posture, preferably also based on a known, in one embodiment, predetermined and / or measured third end position or another second end position, wherein, in one embodiment, the third end position or the other second end position is known, preferably predetermined and / or measured relative to the robot arm, in particular its base and / or relative to the environment of the robot arm, in particular the base of a measuring device.

[0029] In one embodiment, the calibration, in particular its accuracy and / or the determination of a plurality of dimensions or parameters can be improved by one or more second calibration elements which are preferably spaced apart (arranged) from one another and / or from the first calibration element.

[0030] In one embodiment, the method comprises the following steps:

[0031] - adjusting the robot arm from a first calibration posture into at least one further calibration posture, in which the calibration element attached to the robot arm is (likewise) arranged in a first end position, wherein the calibration element attached to the robot arm preferably remains arranged in the first end position during the adjustment process by means of the robot arm which is force-controlled for this purpose, or is guided again into the first end position by the first calibration element in the first feed direction during a force-controlled movement of the calibration element attached to the robot arm relative to the first calibration element; and

[0032] - detecting a further pose of the joint of the robot arm in the further calibration pose;

[0033] Therein, the robot arm is calibrated based on the first joint pose and the further joint pose.

[0034] Additionally or alternatively, in one embodiment, the method comprises the following steps:

[0035] - adjusting the robot arm from the or at least one second calibration posture into at least one further calibration posture, in which the calibration element fixed to the robot arm is arranged in the second end position in which it was in the second calibration posture, wherein preferably the calibration element fixed to the robot arm remains arranged in the second end position during the adjustment process by means of the robot arm which is force-controlled for this purpose, or is guided again into the (respective) second end position by the respective second calibration element in the force-controlled movement of the calibration element fixed to the robot arm relative to the second calibration element along the (respective) second feed direction; and

[0036] - detecting a further pose of the joint of the robot arm in the further calibration pose;

[0037] Therein, the robot arm is also calibrated based on the further joint pose.

[0038] Thus, in one embodiment, different calibration poses or joint poses of the robot arm can be detected in the same or for the same end position and used for calibration, in particular to improve the calibration, in particular its accuracy and / or to improve the time and / or space requirements and / or to determine multiple dimensions or parameters.

[0039] In one embodiment, when the robot arm is adjusted from a first calibration posture to another calibration posture (a calibration element fixed to the robot arm is arranged in a first end position in the other calibration posture), when the robot arm is adjusted between at least two calibration postures A and B of the robot arm (one of the calibration postures may be the first calibration posture, or the two calibration postures may be different from the first calibration posture), the calibration element fixed to the robot arm is arranged in the first end position, and the direction of the calibration element fixed to the robot arm relative to the first calibration element (in this adjustment of the robot arm between the two calibration postures A and B of the robot arm) remains unchanged, and during the detection process, the postures of the joints of the robot arm in the at least two calibration postures A and B are detected, and the robot arm is calibrated (also) based on the detected postures of the joints.

[0040] Additionally or alternatively, in one embodiment, when the robot arm is adjusted from the or at least one second calibration posture to the or at least one other calibration posture (the calibration element fixed to the robot arm is arranged in the (corresponding) second position in the other calibration posture, and it is in the (corresponding) second calibration posture in the second position), when the robot arm is adjusted between at least two calibration postures A', B' of the robot arm (one of the calibration postures may be the (corresponding) second calibration posture, or the two calibration postures may be different from the (corresponding) second calibration posture), the calibration element fixed to the robot arm is arranged in the (corresponding) second end position, and the direction of the calibration element fixed to the robot arm relative to the (corresponding) second calibration element (in this adjustment of the robot arm between the two calibration postures A', B' of the robot arm) remains unchanged, and during the detection process, the postures of the joints of the robot arm in the at least two calibration postures A', B' are detected, and the robot arm is calibrated (also) based on the detected postures of the joints.

[0041] In one embodiment, the robot arm is therefore (respectively) configured to not only maintain the position of a calibration element fixed to the robot arm relative to the respective calibration element, but also to maintain its orientation or to adjust it in its respective null space.

[0042] Thus, in one embodiment, preferably at a (lower) load on the calibration element, other joint positions for calibration can be particularly advantageously entered. Additionally or alternatively, in one embodiment, additional joint positions can be used for calibration by adjusting the robot arm in the corresponding null space.

[0043] Additionally or alternatively, in one embodiment, when the robot arm is adjusted from a first calibration posture to another calibration posture (in the other calibration posture, the calibration element fixed to the robot arm is arranged in a first end position), in at least two calibration postures U, V of the robot arm (one of the calibration postures may be the first calibration posture, or the two calibration postures may be different from the first calibration posture), the calibration element fixed to the robot arm is arranged in the first end position, and the calibration element fixed to the robot arm has a different orientation relative to the first calibration element in the at least two calibration postures U, V, or changes its orientation relative to the first calibration element when the robot arm is adjusted between the two calibration postures U, V of the robot arm, and during the detection process, the postures of the joints of the robot arm in the at least two calibration postures U, V are detected, and the robot arm is calibrated (also) based on the acquired joint postures.

[0044] Additionally or alternatively, in one embodiment, when the robot arm is adjusted from the or at least one second calibration posture to the or at least one other calibration posture (in the other calibration posture, the calibration element fixed to the robot arm is arranged in the (corresponding) second end position, and it is arranged in the (corresponding) second calibration posture at the second end position), between at least two calibration postures U', V' of the robot arm (one of the calibration postures may be the (corresponding) second calibration posture, or the two calibration postures may be different from the (corresponding) second calibration posture), the calibration element fixed to the robot arm is arranged in the (corresponding) second end position, and the calibration element fixed to the robot arm has different directions relative to the (corresponding) second calibration element in the at least two calibration postures U', V', or when the robot arm is adjusted between the two calibration postures U', V' of the robot arm, its direction relative to the (corresponding) second calibration element is changed, and during the detection process, the postures of the joints of the robot arm in the at least two calibration postures U', V' are detected, and the robot arm is (also) calibrated based on the detected joint postures.

[0045] Thus, in one embodiment, only the position of the calibration element fixed to the robot arm relative to the corresponding calibration element is maintained, but its orientation relative to the corresponding calibration element is changed.

[0046] Thus, in one embodiment, it is advantageously possible to (more) simply and / or (more) precisely move into other joint poses for calibration and / or use additional joint poses for calibration, in particular when the robot arm does not have a corresponding zero space in the corresponding initial (calibration) pose.

[0047] It is particularly advantageous that the two variants described above can be combined with one another, in particular sequentially, in particular by adjusting the robot arm while maintaining the position and orientation after the robot arm has been adjusted between two calibration postures in which the calibration element fixed to the robot arm has different orientations but the same position relative to the corresponding calibration element, and / or adjusting the robot arm while maintaining the position and changing the orientation after the robot arm has been adjusted between two calibration postures in which the calibration element fixed to the robot arm has the same position and orientation relative to the corresponding calibration element.

[0048] As a result, additional joint positions can be used particularly advantageously for calibration and thus improve the calibration, in particular its accuracy and / or speed. It is particularly advantageous if more than two calibration positions can be entered while maintaining the position and orientation of the calibration element fixed to the robot arm relative to the corresponding calibration element and the joint positions detected in these calibration positions can be used for calibration.

[0049] In one embodiment, in a first calibration posture, in an extended scheme, when adjusting from the first calibration posture to another calibration posture and / or at least during the detection of the joint posture in the first and / or the other calibration posture, the robot arm is force-regulated so that a calibration element fixed to the robot arm applies a contact force to the first calibration element in a first end position and is supported in the first end position by the first calibration element.

[0050] Additionally or alternatively, in the or at least one second calibration posture, in an extended embodiment, during adjustment from the or at least one second calibration posture to a corresponding another calibration posture, and / or at least during detection of the joint posture in the (corresponding) second and / or the other calibration posture, the robot arm is force-regulated so that a calibration element fixed to the robot arm applies a contact force to a corresponding second calibration element in the (corresponding) second end position and is supported in the (corresponding) second end position by the corresponding second calibration element.

[0051] In one embodiment, a calibration element fastened to the robot arm can thereby advantageously be fixed in its respective end position, so that in particular the calibration, in particular its accuracy and / or time requirement, can be improved.

[0052] In one embodiment, the first calibration element has a guide surface with a recess The calibration element, which is fastened to the robot arm, can be supported by the recess in a defined support position which determines a first end position, wherein the guide surface converges toward the recess, preferably in a funnel-shaped manner.

[0053] In an extended embodiment, the one or more second calibration elements (respectively) have a guide surface with a recess, wherein the calibration element fixed to the robot arm can be supported by the (respective) recess in a defined support position, which determines the (respective) second end position, wherein the guide surface preferably converges towards the recess in a funnel shape. Additionally or alternatively, the calibration element fixed to the robot arm has an at least partially spherical or (partially) spherical contact surface or surface for sliding on the (respective) guide surface. Additionally or alternatively, in one embodiment, the one or more guide surfaces (respectively) have one or more guide parts (Führung), which are designed to guide the calibration element (respectively) fixed to the robot arm along a one-dimensional, preferably at least partially linear guide trajectory into the (respective) recess.

[0054] In another embodiment, on the other hand, the calibration element fixed to the robot arm has a guide surface with a recess, wherein the first calibration element can be supported by the recess in a defined support position, which determines the first end position, wherein the guide surface preferably converges in a funnel shape toward the recess.

[0055] In an extension, the first calibration element and in one embodiment also the one or more second calibration elements (respectively) have an at least partially spherical or (partially) spherical contact surface or surface for sliding on the guide surface. Additionally or alternatively, in one embodiment, the guide surface has one or more guides designed to guide the first or (respectively) second calibration element (respectively) attached to the robot arm along a one-dimensional, preferably at least partially linear guide path into the (respective) recess.

[0056] In one embodiment, the mechanical guidance or form-fitting guidance or alignment, in particular its accuracy and / or its time and / or space requirement, can thereby be improved.

[0057] In one embodiment, the method comprises the following steps:

[0058] - a calibration element fixed to the robot arm is moved relative to the first calibration element in a force-controlled manner by the robot arm, wherein the calibration element fixed to the robot arm is guided along a guide path by a guide during this movement and the posture of the joint of the robot arm is detected in at least two calibration postures;

[0059] The robot arm is calibrated based on the joint posture.

[0060] In one embodiment, the method comprises the following steps:

[0061] - a calibration element fixed to the robot arm is moved relative to the or one or more second calibration elements in a force-controlled manner by the robot arm (respectively), wherein the calibration element fixed to the robot arm is guided along a guide path during this movement by a (corresponding) guide, and thereby the pose of the joints of the robot arm is detected in at least two calibration poses;

[0062] The robot arm is calibrated based on the joint posture.

[0063] In one embodiment, the or one or more guide sections (respectively) have at least one edge, preferably a groove, in the guide surface.

[0064] In one embodiment, a defined direction is provided by the (corresponding) guide, which can be detected by at least two calibration postures and thus advantageously used for calibration. Thus, in one embodiment, calibration, in particular its accuracy and / or time and / or space requirements, can be improved.

[0065] According to one specific embodiment of the present invention, a system is provided which is designed in terms of hardware and / or software, in particular in terms of programming, to carry out the method described herein.

[0066] According to one specific embodiment of the invention, the system comprises a measuring device described here, in particular can consist of it.

[0067] Additionally or alternatively, according to one embodiment of the invention, the system has a controller which is designed in terms of hardware and / or software, in one embodiment in particular in terms of program technology, for the following, in particular consisting of:

[0068] - controlling the robot arm so as to position the calibration element fixed to the robot arm in one of the first starting positions relative to the first calibration element by means of the robot arm;

[0069] - controlling the robot arm in order to move a calibration element fixed to the robot arm relative to a first calibration element in a force-controlled manner in a first feed direction by means of the robot arm, wherein the calibration element fixed to the robot arm is guided into a first end position by means of the first calibration element during this movement and the robot has a first calibration pose in this first end position; and

[0070] - detecting a first pose of the joints of the robot arm in a first calibration pose, preferably by means of corresponding sensors.

[0071] Additionally or alternatively, according to one embodiment of the invention, the system, in particular its controller, has, in particular may consist of, a calibration element for calibrating the robot arm based on the detected first joint pose.

[0072] In one specific embodiment, the control unit is designed, in particular in terms of hardware and / or software, in one specific embodiment in terms of program technology, to:

[0073] - controlling the robot arm so as to position the calibration element fixed to the robot arm in one of the second starting positions relative to the second calibration element by means of the robot arm;

[0074] - controlling the robot arm in order to move the calibration element fixed to the robot arm relative to the second calibration element in a force-controlled manner in a second feed direction by means of the robot arm, wherein the calibration element fixed to the robot arm is guided into a second end position by means of the second calibration element during this movement and the robot has a second calibration posture in this end position; and

[0075] - detecting a second pose of the joint of the robot arm in a second calibration pose, preferably by means of corresponding sensors;

[0076] And / or, the calibration piece is designed to calibrate the robot arm based on the first and second joint postures.

[0077] In one embodiment, the controller is designed, in particular in terms of hardware and / or software, in one embodiment in terms of programming, for

[0078] - controlling the robot arm in order to adjust the robot arm from the first calibration posture into at least one further calibration posture in which the calibration element fixed to the robot arm is arranged in the first end position; and

[0079] - detecting a further pose of the joint of the robot arm in the further calibration pose, preferably by means of corresponding sensors;

[0080] And / or, the calibration piece is designed to calibrate the robot arm based on the additional joint pose.

[0081] In one embodiment, the controller is designed, in particular in terms of hardware and / or software, in one embodiment in terms of programming, for

[0082] - when adjusting the robot arm from a first calibration posture to another calibration posture in which the calibration element fixed to the robot arm is arranged in a first end position, when adjusting the robot arm between at least two calibration postures of the robot arm, the calibration element fixed to the robot arm is arranged in the first end position, and the orientation of the calibration element fixed to the robot arm relative to the first calibration element is maintained, and during the detection process, the postures of the joints of the robot arm in the at least two calibration postures are detected; and / or

[0083] - when adjusting the robot arm from a first calibration posture to a further calibration posture in which the calibration element fixed to the robot arm is arranged in a first end position, the calibration element fixed to the robot arm is arranged in the first end position in at least two calibration postures of the robot arm, and the calibration element fixed to the robot arm has different orientations relative to the first calibration element in the at least two calibration postures, and the postures of the joints of the robot arm in the at least two calibration postures are detected during the detection process,

[0084] And / or, the calibration piece is designed to calibrate the robot arm (also) based on the detected joint pose.

[0085] In one embodiment, the controller is designed, in particular in terms of hardware and / or software, in one embodiment, in terms of programming, for

[0086] - controlling the robot arm in order to move a calibration element fastened to the robot arm relative to the first calibration element in a force-controlled manner by the robot arm, wherein the calibration element fastened to the robot arm is guided along a guide path during this movement by a guide, and thereby detecting the pose of a joint of the robot arm in at least two calibration poses, preferably by means of corresponding sensors;

[0087] And / or, the calibration piece is designed to calibrate the robot arm of the joint posture.

[0088] The system and / or device within the meaning of the present invention can be designed in hardware technology and / or software technology, in particular, it has: at least one processing unit, in particular a digital processing unit, in particular a microprocessor unit (CPU), a graphics card (GPU), etc., which is preferably connected to a storage system and / or a bus system for data or signals, and / or one or more programs or program modules. The processing unit can be designed to: process the instructions of the program implemented as a program stored in the storage system; collect input signals from the data bus; and / or send output signals to the data bus. The storage system can have one or more, in particular different storage media, in particular optical, magnetic, solid and / or other non-volatile media. The program can be implemented so that it can embody or execute the method described herein, so that the processing unit can perform the steps of this method and thereby can control and / or calibrate the robot arm in particular. Control within the meaning of the present invention can also be understood in particular as adjusting or issuing commands based on the deviation between the target value and the actual value. In one embodiment, the computer program product can have, in particular, a computer-readable, non-volatile storage medium for storing programs or instructions or a storage medium on which a program is stored or on which instructions are stored. In one embodiment, executing the program or the instructions by a system or a controller, in particular a computer or a plurality of computer arrays, will allow the system or the controller, in particular one or more computers, to perform the method described herein or one or more steps thereof, or the program or the instructions are designed for this purpose.

[0089] In one embodiment, one or more, in particular all steps of the method are fully or partially implemented by a computer, or one or more, in particular all steps of the method are fully or partially performed automatically, in particular automatically performed by the system or its device.

[0090] In one specific embodiment, the system has a robotic arm.

[0091] The calibration of the robot arm can in particular comprise determining parameters of a model of the robot arm, preferably parameters of a kinematic model.

[0092] In one embodiment, such a model describes the pose q of the joints of the robot arm and the pose X of a reference object fixed to the robot, preferably an end flange, an end effector, a TCP, etc., and depends on a parameter p, wherein the pose can describe a one-dimensional, two-dimensional or three-dimensional position and / or a one-dimensional, two-dimensional or three-dimensional orientation in a manner customary in the art (forward kinematics: X=V(q,p) or inverse kinematics q=V(X,p')). According to the corresponding value pair {X i ,q i}, the parameters can be determined in a known manner, for example by making the measurement error Σ|X i -V(q i,p)|minimize, etc.

[0093] The calibration of the robot arm can in particular comprise the determination of a transformation between a coordinate system fixed to the robot arm and a coordinate system fixed to the environment.

[0094] In one embodiment, the pose of the calibration element fixed to the robot arm can be described on the one hand by a transformation from a coordinate system fixed to the environment to a coordinate system fixed to the base of the robot arm and then (in particular by a model of the robot arm, preferably a kinematic model, according to its joint poses) to a coordinate system fixed to the end flange and the pose of the calibration element fixed to the robot arm described therein; on the other hand, it can also be described in a coordinate system fixed to the environment and the pose of the calibration element fixed to the robot arm in the corresponding end position described therein. Accordingly, it is possible to describe the pose of the calibration element fixed to the robot arm in the corresponding end position according to the corresponding value pair {X i ,q i}, determining in a known manner a transformation between a coordinate system fixed to the environment and a coordinate system fixed to the base of the robot arm (and thus in one embodiment determining the posture of the robot arm or its base relative to the coordinate system fixed to the environment) and / or determining a transformation between a coordinate system fixed to the end flange and a coordinate system fixed to the end effector or to the calibration element.

[0095] In one embodiment, the robot arm is generally calibrated based on the detected (first, further and / or second) joint poses and the known, in one embodiment predefined and / or measured, end positions.

[0096] In one embodiment, the detecting comprises detecting and / or storing the measured value, preferably by sensory means.

[0097] In one embodiment, the calibration element attached to the robot arm exerts a contact force, in one embodiment a preset or target contact force, on the first calibration element when moving into the first end position due to the force-controlled movement, and / or exerts a contact force, in one embodiment a preset or target contact force, on the second calibration element when moving into the second end position. In one embodiment, the entry into the end position and thus the calibration, in particular its accuracy and / or time requirement, can be improved. Additionally or alternatively, it is particularly advantageous that the corresponding feed direction can deviate from the direction of gravity, for example the robot arm also moves the calibration element attached to the robot arm horizontally, over the head or similarly into the corresponding end position.

[0098] In one embodiment, the force-regulated movement can also include an additional position regulation, in particular a mixed force-position regulation. In particular, the force-regulated movement along the feed direction can include a position regulation movement along the feed direction and a force-regulated movement transverse thereto, in particular an offset.

[0099] In one embodiment, the force-regulated movement in the feed direction within the meaning of the present invention may have or include, in addition to a (movement) component in the feed direction, a (movement) component transverse to the feed direction, which (movement) component is advantageously realized by the contact of the calibration element fixed to the robot arm, or the first or second calibration element, in a form-fitting or mechanical manner. Accordingly, in one embodiment, when the calibration element fixed to the robot arm is displaced in the feed direction relative to the contacted, or the first or second calibration element, the calibration element fixed to the robot arm may, in addition to the displacement, perform a movement transverse to the feed direction relative to the contacted calibration element, which is realized by the contacted, or the first or second calibration element, in a form-fitting or mechanical manner. Therefore, in one embodiment, when the calibration element fixed to the robot arm is moved along the first or second feed direction relative to the contacted or first or second calibration element, the force regulation causes a relative movement transverse to the feed direction that is coupled to the displacement along the feed direction, in particular mechanically and / or form-fittingly coupled, thereby guiding the calibration element fixed to the robot arm to the corresponding end position while using or fully utilizing a single degree of freedom, in particular the degree of freedom along the feed direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Further advantages and features are given by the dependent claims and the embodiments. To this end, a partial schematic diagram is shown:

[0101] Figure 1 A system according to an embodiment of the present invention;

[0102] Figure 2 for Figure 1 a top view of a first calibration element; and

[0103] Figure 3 This is a method according to one embodiment of the present invention. DETAILED DESCRIPTION

[0104] Figure 1 A system according to an embodiment of the present invention is shown, the system comprising a robot arm 1 and a controller 3 for controlling the robot arm 1, the robot arm having a robot arm base and an end flange 1.2, a coordinate system B fixed to the robot arm base determined with respect to the robot arm base, and a coordinate system F fixed to the end flange determined with respect to the end flange.

[0105] Arranged on the end flange 1 . 2 is a calibration element of the measuring device of the system, which is fixed to the robot arm and has a partially spherical surface or contact face 2 .

[0106] The measuring device also has a first calibration element 10, which has a guide surface 10.1, which is formed by a pyramid-shaped depression, the edges 11 of which (in the embodiment, there are four of them by way of example) form a guide for guiding the spherical surface or contact surface of the calibration element 2 fixed to the robot arm along a one-dimensional linear guide path. Figure 1 It is shown with cross-hatching for illustrative purposes and forms a recess 12, in which the spherical surface or contact surface of the calibration element 2 fixed to the robot arm will eventually stop in a well-defined first position in a form-fitting manner when inserted into the recess; wherein the guide surface 10.1 converges towards the recess 12 in a funnel shape.

[0107] The measuring device also has a second calibration element 20, which has a guide surface 20.1, which is formed by a conical recess, the tip area of ​​which similarly enables the spherical surface or contact surface of the calibration element 2 fixed to the robot arm to eventually stop in a well-defined second position in a shape-fitting manner when inserted into the recess.

[0108] In order to calibrate the robot arm 1, the controller 3 first controls it to the following posture: in this posture, the spherical surface or contact surface of the calibration element 2 fixed to the robot arm is at least partially roughly positioned inside the recess of the first calibration element 10 ( Figure 3 :Step S10).

[0109] Then, the controller 3 causes the robot arm 1 to move accordingly in a force-controlled manner, thereby using the robot arm 1 to cause the calibration element 2 fixed to the robot arm to move relative to the first calibration element 10 along the first feed direction (in Figure 1 Move vertically downward Figure 3 :Step S20).

[0110] During this movement, the calibration element 2 attached to the robot arm encounters the guide surface 10.1. It is then introduced further into the recess in a force-controlled manner by means of the robot arm 1, first to an edge 11 and then along this edge into the recess 12, where it is guided mechanically or form-fittingly by the guide surface 10.1 or the edge 11.

[0111] When the calibration element fixed to the robot arm stops in the recess 12 and has a first end position X 1 When the robot arm 1 is in the first calibration posture, the posture q of its joint is detected. 11 , which is Figure 1 In the example, it is marked as 1.1 ( Figure 3 : Step S30), wherein the calibration element fixed to the robot arm continues to exert a contact force on the guide surface 10.1 in a force-controlled manner in the recess 12 during this detection.

[0112] Prior to this, when passing the edge 11 , the pose position q of the joint is detected in a further calibration pose of the robot arm 1 , which is experienced here. 10 At least once.

[0113] While the calibration element fixed to the robot arm continues to exert a contact force in the recess 12 on the guide surface 10.1 in a force-controlled manner, the robot arm 1 is adjusted from the first calibration posture to at least one other calibration posture, wherein the calibration element fixed to the robot arm continues to be held in the first end position or is held in the first end position by the force-controlled contact force in cooperation with the recess 12 ( Figure 3 : Step S40). The posture q of the joint is also detected in this other calibration posture 12 ( Figure 3 : Step S50), wherein the calibration element fixed to the robot arm continues to exert a contact force on the guide surface 10.1 in a force-controlled manner in the recess 12 during the detection.

[0114] In this case, in one embodiment, the direction of the calibration element fixed to the robot arm relative to the first calibration element 10 can be changed when adjusted to another calibration posture. Accordingly, in one embodiment, while maintaining the direction of the calibration element fixed to the robot arm relative to the first calibration element and the first end position, the robot arm 1 can be adjusted to at least one other calibration posture, and the posture of the joint can also be detected in the other calibration posture. Similarly, when the robot arm 1 is adjusted from the first calibration posture to another calibration posture, the calibration element fixed to the robot arm can not only maintain the first end position, but also maintain its direction relative to the first calibration element, and if necessary, the robot arm can be adjusted to at least one other calibration posture while maintaining the first end position of the calibration element fixed to the robot arm, and change its direction relative to the first calibration element.

[0115] Then, in a similar manner, the spherical surface or contact surface of the calibration element 2 fixed to the robot arm is at least partially roughly positioned inside the recess of the second calibration element 20 by the robot arm 1 ( Figure 3 :Step S60).

[0116] Then, the controller 3 causes the robot arm 1 to move accordingly in a force-adjusted manner, thereby causing the calibration element fixed to the robot arm to move relative to the second calibration element along the second feed direction (in Figure 1 Move vertically downward in the same way ( Figure 3 :Step S70).

[0117] During this movement, the calibration element fixed to the robot arm hits the guide surface 20.1. It is then introduced further into the recess in a force-controlled manner by means of the robot arm 1 until it enters the tip area of ​​the conical recess and is there mechanically or positively guided by the guide surface 20.1.

[0118] When the calibration element fixed to the robot arm stops in the second recess 22 formed by the tip region and has a second end position X 2 When the robot arm 1 is in the second calibration posture, the posture q of its joint is detected. 21 ( Figure 3 : Step S80), wherein the calibration element 2 fixed to the robot arm continues to exert a contact force on the guide surface 20.1 in a force-controlled manner in the recess 22 during this detection.

[0119] While the calibration element 2 fixed to the robot arm continues to exert a contact force on the guide surface 20.1 in a force-controlled manner in the recess 22, the robot arm 1 is adjusted from the second calibration posture to at least one other calibration posture, wherein the calibration element fixed to the robot arm continues to remain arranged in the second end position or remains in the second end position in cooperation with the recess 22 by a force-controlled contact force ( Figure 3 : Step S90). In this other calibration posture, the posture q of the joint is also detected. 22 ( Figure 3 : step S100), wherein the calibration element fixed to the robot arm continues to exert a contact force on the guide surface 20.1 in a force-controlled manner in the recess 22 during this test. As explained above with respect to the first calibration element, the calibration element fixed to the robot arm can have the same end position and different directions and / or the same end position and direction in two or more calibration postures.

[0120] The end position is known in a coordinate system W fixed to the environment, for example pre-set based on measurements. Then, in step S110, the kinematic model of the robot arm 1 can be calibrated in the following way: that is, purely by way of example, the parameters p of the model V are determined so that the deviation |X 1 –V(q 12 ,p)|+|X 1 –V(q 22 ,p)|+|X 2 –V(q 21 ,p)|+|X 2 –V(q 22 , p)| and is the smallest.

[0121] Additionally or alternatively, in step S110, the transformation between the coordinate system W fixed to the environment and the coordinate system B fixed to the robot arm base and / or the transformation between the coordinate system F fixed to the end flange and the coordinate system T fixed to the robot tool can be determined in a known manner, for example based on the relationship F T T · B T F (q) W T B = W T F ,in, W T B represents the (sought) transformation from a coordinate system W fixed to the environment to a coordinate system B fixed to the base of the robot arm (which determines the pose of the robot base relative to the environment or the coordinate system W fixed to the environment); B T F represents the transformation from the coordinate system B fixed to the base of the robot arm to the coordinate system F fixed to the end flange, determined with the aid of the or a kinematic model, depending on the joint pose q; F T T represents the (sought-after) transformation from a coordinate system F fixed to the end flange to a coordinate system T fixed to the robot tool (which determines the pose of the robot tool relative to the end flange); and B T T represents the transformation from the coordinate system W fixed to the environment to the coordinate system fixed to the robot tool arranged in the respective end positions, which can be determined based on the measurement of the recesses 12, 22 relative to W. The different detected joint poses and the known respective end positions are used again in this calibration.

[0122] Additionally, by two gestures q along edge 11 10 ,q 11 (their orientation relative to W is known based on measurements of the guide surface 10 . 1 ), in addition to this position, the orientation of a coordinate system fixed to the robot tool arranged in the first end position is also known and can advantageously be used for the above calibration.

[0123] While exemplary embodiments have been set forth in the foregoing description, it should be noted that many variations are possible.

[0124] The first and second calibration elements have been explained purely by way of example, one of which purely by way of example has a guide surface in the form of a pyramidal recess (the edges of which form a guide portion for guiding the calibration element fixed to the robot arm along a one-dimensional linear guide trajectory into the recess 12), and the other of which purely by way of example has a guide surface in the form of a conical recess. Of course, the two calibration elements can also each have a pyramidal or conical recess or another type of recess. Additionally or alternatively, other pyramid shapes can also be used instead of a pyramid shape with four edges, for example only with three edges. Additionally or alternatively, one or more further second calibration elements can be similarly arranged or used, as purely by way of example described with respect to the second guide surface 20.1. Additionally or alternatively, one or more calibration elements can be oriented in another way relative to the environment, for example with a horizontal or upward feed direction, which can in particular improve flexibility and / or space requirements.

[0125] As already mentioned, the force-controlled movement can also include an additional position control, in particular a mixed force-position control. Purely by way of example, in the above-described embodiment, the feed movement in the respective feed direction can be carried out in a position-controlled manner in the feed direction, and the robot arm 1 is here transverse to the feed direction with the calibration element 2 fixed to the robot arm, i.e. horizontal in this embodiment, because the guidance is deflected in a force-controlled manner by the corresponding calibration element fixed to the environment.

[0126] It should also be pointed out that the exemplary embodiment is only an example and does not constitute any limitation on the scope of protection, application and configuration. On the contrary, the above description can provide a person skilled in the art with a teaching for implementing a transformation of at least one exemplary embodiment, wherein various changes, in particular with respect to the function and arrangement of the components, can be implemented without departing from the scope of protection of the present invention, such as can be obtained according to the claims and their equivalent feature combinations.

[0127] Reference numerals list

[0128] 1 Robotic Arm

[0129] 1.1 Joints

[0130] 1.2 End flange

[0131] 2Calibration element fixed to the robot arm

[0132] 3 Robot Arm Controller

[0133] 10 First calibration element

[0134] 10.1 Guide surface

[0135] 11 Edge

[0136] 12 Hole

[0137] 20 Second calibration element

[0138] 20.1 Guide surface

[0139] 22 Hole

[0140] B is the coordinate system fixed to the base of the robot arm

[0141] F is the coordinate system fixed to the end flange

[0142] T is fixed to the coordinate system of the robot tool

[0143] W is fixed to the environment's coordinate system.

Claims

1. A method for calibrating a robot arm (1) by means of a measuring device, the robot arm having a plurality of joints (1.1), the measuring device having a first calibration element (10) and a calibration element (2) fixed to the robot arm, the calibration element fixed to the robot arm being movable relative to the first calibration element by adjusting the joints of the robot arm, in, The first calibration element and the calibration element fixed to the robot arm are configured so that, when the calibration element fixed to the robot arm is moved relative to the first calibration element in a first feed direction, the calibration element fixed to the robot arm is guided from different first starting positions to the same defined first end position via the first calibration element; Wherein, the method comprises the following steps: - positioning (S10) the calibration element fixed to the robot arm relative to the first calibration element in one of the first starting positions by means of the robot arm; - by means of the robot arm, the calibration element fixed to the robot arm is moved relative to the first calibration element in a force-controlled manner in the first feed direction (S20), wherein during this movement, the calibration element fixed to the robot arm is guided by the first calibration element to the first end position and the robot has a first calibration pose in this end position; - detecting (S30) a first posture of the joints of the robot arm in the first calibration posture; and - Based on the first joint posture, calibrating ( S110 ) the robot arm.

2. The method according to claim 1, characterized in that The measuring device has at least one second calibration element (20), wherein the second calibration element and the calibration element fixed to the robot arm are configured such that when the calibration element fixed to the robot arm is moved relative to the second calibration element in a second feed direction, the calibration element fixed to the robot arm is guided from different second starting positions to a defined identical second end position via the second calibration element; Wherein, the method comprises the following steps: - positioning (S60) the calibration element fixed to the robot arm relative to the second calibration element in one of the second starting positions by means of the robot arm; - by means of the robot arm, the calibration element fixed to the robot arm is moved relative to the second calibration element in the second feed direction in a force-controlled manner (S70), and the robot has a second calibration posture in this end position; and - detecting (S80) a second posture of the joints of the robot arm in the second calibration posture; wherein, based on the first joint posture and the second joint posture, calibrating (S110) the robot arm.

3. The method according to any one of the preceding claims, characterized in that The following steps are involved: - adjusting (S40) the robot arm from the first calibration pose to at least one further calibration pose, in which further calibration pose the calibration element fixed to the robot arm is arranged in the first end position; and - detecting (S50) a further pose of the joint of the robot arm in the further calibration pose; Wherein, based on the first joint position and another joint posture, the robot arm is calibrated (S110).

4. The method according to claim 3, characterized in that - when the robot arm is adjusted from the first calibration posture to another calibration posture, the calibration element fixed to the robot arm is arranged in the first end position in the other calibration posture, when the robot arm is adjusted between at least two calibration postures of the robot arm, the calibration element fixed to the robot arm is arranged in the first end position, and the orientation of the calibration element fixed to the robot arm relative to the first calibration element remains unchanged, the postures of the joints of the robot arm in the at least two calibration postures are detected during the detection process, and the robot arm is calibrated based on the detected joint postures; and / or -When the robot arm is adjusted from the first calibration posture to another calibration posture, the calibration element fixed to the robot arm is arranged in the first end position in the other calibration posture, and in at least two calibration postures of the robot arm, the calibration element fixed to the robot arm is arranged in the first end position, and the calibration element fixed to the robot arm has different directions relative to the first calibration element in the at least two calibration postures, and the postures of the joints of the robot arm in the at least two calibration postures are detected during the detection process, and the robot arm is calibrated based on the detected joint postures.

5. The method according to any one of the preceding claims, characterized in that The robot arm is force-controlled in the first calibration posture, in particular when adjusting from the first calibration posture to another calibration posture, so that the calibration element fixed to the robot arm exerts a contact force on the first calibration element in the first end position and is supported in the first end position by the first calibration element.

6. The method according to any one of the preceding claims, characterized in that One of the first calibration element and the calibration element fixed to the robot arm has a guide surface (10.1), which has a recess (12), wherein the other of the first calibration element and the calibration element fixed to the robot arm can be supported at a defined support position by the recess, and the defined support position determines the first end position, wherein the guide surface converges toward the recess.

7. The method according to the preceding claim, characterized in that The guide surface has at least one guide portion (11) for guiding the other of the first calibration element and the calibration element fixed to the robot arm into the recess along a one-dimensional guide trajectory.

8. The method according to the preceding claim, characterized in that The following steps are involved: - With the aid of the robot arm, the calibration element fixed to the robot arm is moved in a force-adjusted manner relative to the first calibration element (S20), wherein the calibration element fixed to the robot arm is guided along the guide trajectory by the guide part during the movement, and the postures of the joints of the robot arm are detected (S20, S30) in at least two calibration postures accordingly; wherein the robot arm is calibrated based on the postures of these joints (S110).

9. A system for calibrating a robot arm (1) having a plurality of joints (1.1), the system being designed to carry out the method according to any one of the preceding claims and / or having: A measuring device having a first calibration element (10) and a calibration element (2) which can be arranged on the robot arm, wherein: The first calibration element and the calibration element that can be arranged on the robot arm are constructed so that when the calibration element that can be arranged on the robot arm is arranged on the robot arm, the calibration element fixed to the robot arm can be moved relative to the first calibration element by adjusting the joint of the robot arm, and when the calibration element fixed to the robot arm is displaced along a first feed direction relative to the first calibration element, the calibration element fixed to the robot arm is respectively guided from different first starting positions to the same defined first end position through the first calibration element; and / or Controller for controlling the robot arm so as to position the calibration element fixed to the robot arm in one of the first starting positions relative to the first calibration element by means of the robot arm; controlling the robot arm in order to move the calibration element fixed to the robot arm relative to the first calibration element in a force-controlled manner in the first feed direction by means of the robot arm, wherein the calibration element fixed to the robot arm is guided into the first end position by the first calibration element during this movement and the robot has a first calibration pose in the first end position; and detecting a first posture of a joint of the robot arm in the first calibration posture; and / or A calibration piece is used to calibrate the robot arm based on a first joint posture.

10. A computer program or a computer program product, wherein: The computer program or computer program product comprises instructions, in particular instructions stored on a computer-readable and / or non-volatile storage medium, which, when executed by one or more computers or a system according to claim 9, cause the one or more computers or the system to perform a method according to any one of claims 1 to 8.

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