EP3362229A1

EP3362229A1 - Haptic referencing of a manipulator

Info

Publication number: EP3362229A1
Application number: EP16778994.0A
Authority: EP
Inventors: Klaus Miller
Original assignee: KUKA Deutschland GmbH
Current assignee: KUKA Deutschland GmbH
Priority date: 2015-10-15
Filing date: 2016-10-07
Publication date: 2018-08-22
Also published as: WO2017063733A1; DE102015220066A1

Abstract

The present invention relates to a method for controlling a robot system, and in particular for orienting a robot system with respect to a reference body. The robot system in this case comprises a manipulator and a mobile platform that supports the manipulator. In this case, a reference position of the platform with respect to the reference body and a reference configuration of the manipulator are provided. Furthermore, the manipulator is coupled to the reference body and the robot system is actuated in the coupled state such that the reference configuration of the manipulator is taken up.

Description

Haptic referencing of a manipulator l. Technical part

The present invention relates to a method for controlling a

Robot system, and in particular for aligning a robot system to a reference body. Furthermore, the invention relates to a corresponding

Robot system.

2. Technical background

Robots are freely programmable, program-controlled

Handling equipment that can be used for various activities in assembly or manufacturing processes. The actual mechanics of a robot can be called a manipulator. A manipulator may include various members and axes whose movement may be controlled by driving respective motors, and in particular servomotors. Manipulators may be provided on mobile platforms which may, for example, move the manipulators through a factory floor. The platforms can be active or passive, that is, have a standalone drive and independent control or not.

In an automatic program sequence, such a mobile manipulator can be moved to a workpiece in order to subsequently process it. When positioning the mobile manipulator, odometry or laser navigation can be used. However, due to inaccuracies of the hardware and software involved in such positioning, it is an accurate one

Referencing to the workstation necessary. It may be a preferred goal of such referencing, a manipulator in such a way

Workstation to align a defined transformation between a coordinate system of the workstation and a coordinate system of the workstation

CONFIRMATION COPY mobile manipulator is given. An appropriate control is thus known exactly where the mobile manipulator is with respect to the workstation and the component to be processed. Subsequently, an automatic processing step of a robot program can be executed without restrictions.

From in-house procedures is known, sensor-aided

Identify positioning errors. For this purpose, optical

Detection systems in conjunction with algorithms for object or

Environment detection can be used.

The patent US 6,429,016 Bi relates to automatic systems for

Positioning a sample. A positioning system disclosed therein includes a macro-positioning subsystem and a micro-positioning subsystem. The micro-positioning system is provided between a robot and a workstation to enable a fine mechanical positioning.

The document EP 2 590 787 Bi relates to a method for calibrating a robot. For this purpose, a CAD model is generated by means of a CAD software, and then compared with a second CAD model, which was generated based on 3D measurements.

It is an object of the present invention to provide a method for efficiently referencing a robot system to a workstation, for example, so that the path or processing points stored during a programming process can be successfully started or stopped. In particular, a method is to be provided which enables an unrestricted automatic and precise application sequence of a mobile manipulator. Cost-intensive external sensors for aligning should preferably be dispensed with here. These and other objects, which will become apparent from the following description, are achieved by a method according to claim 1 and by

Robot system according to claim 11 solved.

3. Content of the invention The present invention relates to a method for controlling a

Robot system. In particular, by means of this method, the robot system can be aligned to a workstation at which a work step is to be performed by means of the robot system. This can be the

Reference the robot system to the workstation. Particularly preferably, the robot system can align itself by means of the method according to the invention to such a workstation and subsequently handle a component based on the orientation. The workstation can include the component.

The robotic system includes a manipulator as well as a mobile platform supporting the manipulator. Preferably, the manipulator is a

multi-axis articulated arm robot. The mobile platform can be part of

Manipulator, for example, a movable manipulator foot. Alternatively, the mobile platform can also be provided as a separate transport system, which can enable an autonomous movement of the manipulator.

In particular, the mobile platform may be an omnidirectionally mobile platform. The platform may be passively movable, and may be pushed by an operator, for example. The platform can also have its own drive and corresponding control. Preferably, the mobile platform is connected to the manipulator.

The method includes providing a reference body. This

Reference body may for example be arranged on a workstation or a component, and is preferably fixed in place and provided separately from the manipulator and the mobile platform.

The method further comprises providing a reference position of the platform and a reference configuration of the manipulator. The Reference position of the platform may refer to the reference body and may further correspond to a certain transformation between the reference body and the platform. The reference position and the reference configuration may, for example, have been detected during a previous application programming. The reference position of the platform may, for example, comprise a two-dimensional position and an orientation of the platform. The reference configuration of the manipulator may include, for example, an axis configuration of the manipulator or a pose of the manipulator.

The method further includes approximating the platform to the provided reference position of the platform. For this purpose, the mobile platform can be actively controlled, or passively moved by an operator. The approach of the platform can also be done by moving the robot system to the reference body. For example, the platform can be moved here in order to reach the reference position of the platform. The

Reference position does not have to be reached, in particular can not be achieved exactly. For example, such achievement is due to

Positioning errors or manual inaccuracies often not possible.

The method further comprises coupling the manipulator to the

Reference body. By coupling a coupled state of

Robot system achieved by e.g. an end effector of the manipulator grips the reference body. In this case, a direct connection between the manipulator and the reference body can be produced. Thus, the mobile platform is connected via the manipulator with the reference body. Preferably, the coupling is a releasable coupling, so that a coupled state can be canceled after a successful referencing.

Furthermore, the method comprises a control of the robot system in the coupled state, so that the reference configuration of the manipulator is taken. For this purpose, the manipulator and / or the mobile platform can be controlled and moved accordingly. The reference body is preferably not moved in this case to a falsified referencing counteract. Due to the existing coupling between the

Manipulator and the reference body, the manipulator can not move completely free, but is limited due to the coupling in its movement. Following the activation, the manipulator has assumed the reference configuration. Since the manipulator is coupled to the reference body, thus the position and preferably also the orientation of the manipulator are precisely defined, at least with regard to the reference body. Thus, since the manipulator and platform are connected to each other, preferably also the position of the mobile platform with respect to the reference body is precisely defined. The robot system is thus referenced with respect to the reference body. By means of the manipulator, an application can now be performed, with a high accuracy due to the precise referencing of the

Robot system. External sensors for referencing are not necessary. In particular, the steps described above can be carried out automatically, for example before or during an automatic execution of an application. Thus, the robot system can

independently refer to a component by contacting the

Coupled reference body and controls the reference configuration. Preferably, the driving of the robot system in the coupled state further takes place such that the reference position of the mobile platform is taken. For example, if an end effector of the manipulator to the

Reference body is coupled, and a foot of the manipulator is connected to the mobile platform, as a result of driving the robot system, so that the manipulator assumes the reference configuration that with the

Manipulator connected platform occupy the reference position. For this purpose, the mobile platform can be moved as a passive element through the manipulator, so be pushed into the reference position. As an active element, the mobile platform can be controlled accordingly to follow a guidance of the manipulator. For this purpose, a controller of the manipulator may be connected to a corresponding controller of the manipulator. Furthermore, the mobile platform may include sensors that detect forces coming from the Manipulator can be exercised on the platform as a result of driving.

According to this data, the mobile platform can drive its drives to follow the manager of the manipulator.

In the reference position, the position and preferably also the orientation of the mobile platform with respect to the reference body or in terms of the component are precisely defined. The coordinate system of the manipulator, which itself may be defined with regard to the mobile platform, is thus assigned precisely to the reference position of the mobile platform. By means of appropriate transformation, the manipulator can therefore precisely edit a component whose position is stored with respect to the reference body.

Preferably, in the coupled state, there is a connection between the manipulator and the reference body. In particular, preferably a mechanical or magnetic connection between the

Manipulator and the reference body before. Based on this connection, the robot system can align itself if it is driven accordingly, while the manipulator is still connected to the reference body and thus has a fixed reference point, by which the movement takes place as a result of the driving. When coupling, for example, a magnetic

Coupling device of the manipulator are moved efficiently by means of magnetic tensile forces to a ferrous reference body.

Preferably, an intermediate position of the platform is achieved as a result of approaching the platform to the reference position of the platform. These

Intermediate position is typically different from the reference position of the platform. The robot system therefore does not have to be precisely approximated to the reference position of the platform, since the precise alignment or referencing takes place automatically later by means of the manipulator. For example, a worker may manually move the robot system near the reference body and near the reference position of the mobile platform. The platform reaches the intermediate position. In order to perform an accurate execution of a programmed application, is by means of the Manipulator first brought the platform automatically in the reference position.

Preferably, the method further comprises detecting for the

Robot system acting forces and moments. During the approach of the platform and / or during the Koppeins of the manipulator while the robot system and in particular preferably the manipulator is operated by means of a force control using the detected forces and moments. The force control can be a compliance control, and

in particular by means of an impedance, an admittance, a position or torque control. With such a compliance control, the robot system may be at least partially soft-wired and may be regulated according to external forces, so that the external forces acting on the robot system are reduced due to a corresponding movement of the robot system. This allows the manipulator to couple to the reference body without the manipulator and / or the

Reference body be damaged. In particular, a haptisehes coupling can take place, in which the manipulator recognizes the reference body and coupled to these. The approach of the platform to the reference position can also be such that a collision between the robot system and

For example, a workstation on which the reference body may be located is prevented. Thus, a haptisehes referencing can be made possible.

Preferably, the coupling of the manipulator to the reference body comprises a frictional coupling. In particular, preferably due to the Koppeins a frictional connection between the manipulator and the

Reference body before. Thus, the robot system can align itself as a result of the drive while it is in the coupled state. For example, the manipulator can refer to the reference body or from this

push away to enter the reference configuration. The reference body is accordingly fixed and dimensioned sufficiently rigid. Preferably, the coupling of the manipulator to the reference body comprises a positive coupling. In particular, preferably due to the Koppeins a positive connection between the manipulator and the

Reference body before. By this positive locking can be precisely ensured that in the coupled state, a certain predefined orientation between the coupled manipulator and the reference body is present, so easily the reference configuration of the manipulator and the reference position of the mobile platform can be achieved.

Preferably, the coupling of the manipulator to the reference body takes place such that a coupling device of the manipulator is in a predefined orientation relative to the reference body. In particular, the

Coupling device comprise an end effector of the manipulator. In this case, the end effector form the coupling device. The coupling device or the end effector in the coupled state is preferably in a predefined position and orientation with respect to the referent body. By driving the robot system in the coupled state can thus be achieved efficiently a predefined reference configuration and reference position.

In particular, preferably, the coupling of the manipulator takes place at the

Reference body such that a coding of the coupling device of

Manipulator coupled with a corresponding Gegenkodierung the reference body or matches accordingly. The coding and counter-coding may be based on structural features and, for example, due to the key-lock principle, prevent the manipulator from coupling to an incorrect location. Thus, it can be efficiently ensured that the manipulator is coupled to the correct reference body, and that the coupled manipulator is in a desired orientation to the patient

Reference body stands. For this purpose, the coding and counter-coding can be present for example as three-dimensional coding and Gegenkodierflächen, which can only interlock when a certain orientation of the surfaces to each other is present. Preferably, providing the reference position of the platform and the reference configuration of the manipulator comprises moving the mobile platform to a position where the manipulator can reach the reference body, coupling the manipulator to the reference body, and detecting the position as the reference position of the platform and the configuration of the manipulator in the coupled state as the reference configuration of

Manipulator. These steps are preferably done during a

Application programming carried out, and can be at least partially performed or controlled manually by a programmer.

Subsequently, certain application steps can be programmed, such as the storage of a specific gripping point. By means of the method, it is ensured that during an automatic execution of the application exact referencing information is available, by means of which the robot system can precisely refer automatically, so that the following application steps can be carried out precisely. It is thus ensured in particular that the manipulator starting from the

Reference configuration The following application steps as defined during application programming also in automatic mode

can perform.

Furthermore, the present invention comprises a robot system comprising a manipulator and a manipulator-supporting mobile platform.

Preferably, the manipulator is a multi-axis articulated arm robot.

Particularly preferably, the multi-axis articulated robot as

Lightweight robot designed. Furthermore, the robot system has a

Control, which is adapted to perform a method described above for controlling the robot system. One skilled in the art will understand that the robotic system may include corresponding means for performing such a method, such as a coupling device. Preferably, the robot system comprises sensors for detecting on the

Robot system and in particular acting on the manipulator forces and moments. For this purpose, 6-axis force / torque sensors can be used which, based on strain gauges or strain gauges, force- and torque components that act on the manipulator can capture.

4. Examples

In the following, the present invention will be described in detail with reference to the accompanying drawings. Showing:

Figs. 1-5 a robot system according to an embodiment in different constellations.

FIG. 1 shows a robot system comprising a manipulator 4 and a mobile platform 3, which supports the manipulator 4. The mobile platform can be moved in x- and y-direction, and thus the

Manipulator 4 move. The mobile platform 3 may be an omnidirectionally movable platform that can be pushed as a passive platform by a worker. Preferably, the axes of the platform are actively driven, so that the platform can move programmatically automatically and autonomously. For this purpose, the mobile platform may include navigation means, such as lasers. An actively driven platform can also passively be pushed by a worker while the brakes are released.

The manipulator 4 is designed as a multi-axis articulated arm robot, on the hand flange of a gripper 5 and a coupling device 6 are provided in the form of a loop. Furthermore, a workstation 1 is shown in FIG. At this there is a contact device 2, to which the coupling device 6 of the manipulator 4 is coupled. The contact device 2 represents the reference body in the context of the invention.

The following describes the exemplary sequence of application programming with reference to FIGS. 1 and 2. For this purpose, first the mobile platform is moved to a position 7a in which the manipulator 4 with its coupling device 6 can reach the contact device 2. In the case of a passive embodiment of the platform 3, this can be done manually to the

Workstation 1 are pushed. In the case of an actively driven platform 3 this can be moved in manual mode, such as by means of a remote control, in front of the workstation l.

Subsequently, the manipulator 4 is coupled to the contact device 2 as shown in FIG. For this purpose, the manipulator is manually approximated to the workstation 1, and then by means of the coupling device 6 to the

Contact device 2 connected. There is a positive connection 8 between the contact device 2 and the coupling device 6 of the

Manipulator 4 before.

Subsequently, the position 7a of the mobile platform 3 including the translational components xa, ya and the rotational component 0a is stored as the reference position of the mobile platform 3. Likewise, the axle configuration αι, βι, γι, ει the manipulator 4 is stored in the coupled state as the reference configuration of the manipulator.

As shown in FIG. 2, an application can then be programmed. For this purpose, first the coupling between the manipulator 4 and the contact device 2 is released. The mobile platform 3 has not been moved for this purpose in the illustrated embodiment and is still - with activated brakes - at the position 7a. The configuration of the manipulator 4 has been changed according to the application to be programmed, and u.a. a gripping point 9 stored at the workstation 1. For this purpose, the corresponding axis coordinates α2, β2, γ2, ε2 of the manipulator to the

Grab point 9 are stored.

In the following, the automatic execution of the programmed application will be described with reference to Figs. 3-5. For this purpose, the mobile platform 3, which was previously located, for example, at another workstation, approximates to the reference position 7a of the platform. This can for example be done automatically by autonomous navigation or by manual pushing. Due to positioning errors, however, typically only a different intermediate position 7b with the coordinates xb, yb, 6b is achieved. If the programmed application is now executed without referencing would be, would not ensure that the approached to train points that are defined with respect to the workstation ι, precise or due to

Axis limits can be achieved at all with the manipulator. For example, a position can not be approached with sufficient accuracy or can not be achieved due to axle limits. Furthermore, due to the changed initial configuration and the resulting singularities, a linear movement can not be carried out. Furthermore, this could set a singularity of Achsstellung, so that under certain circumstances, a gripping position can not be achieved. As shown in Figure 4, therefore, first by means of an automatic

Search operation of the manipulator coupled the coupling device 6 of the manipulator 4 to the contact device 2 of the workstation 1. For this purpose, the

Manipulator 4 are operated by means of compliance control, so that the positive connection 8 between the coupling device 6 and

Contact device 2 can be achieved easily. In this coupled state, a configuration of the manipulator is associated with e.g. the axis coordinates α3, β3, Y3, £ 3.

Subsequently, the positioning error of the mobile platform 3 is corrected. If the mobile platform 3 is a passive driven platform, the manipulator 4 can be controlled directly in the Referenzachskonfiguration αι, βι, γι, ει. As a result, the mobile platform 3, which is permanently connected to the manipulator 4, is guided or pulled into the associated reference position xa, ya, 0a, as shown in FIG. Subsequently, the coupling can be solved and the following application step can be performed. The base of the manipulator is now in the same place as in the application programming, so that the programmed movement of the manipulator can be performed as desired.

If the platform 3 is an actively driven platform, the reference configuration αι, βι, γι, ει of the. By an inverse kinematics, which includes all degrees of freedom of the overall system, by means of a null space movement

Manipulator and the reference position xa, ya, 0a driven the platform become. Subsequently, the coupling can be solved and the following application step can be performed without any

Repositioning the platform is required to run the previously programmed application program. LIST OF REFERENCE NUMBERS

1 workstation

2 contact device, reference body

3 mobile platform

4 manipulator

5 end effector

6 coupling device

7a, 7b position of the mobile platform

8 connection

9 gripping point

Claims

claims

A method of controlling a robotic system, the robotic system comprising a manipulator (4) and a mobile platform (3) supporting the manipulator (4), the method comprising the following steps:

Providing a reference body (2);

Providing a reference position (7a) of the platform (3) and a reference configuration of the manipulator (4);

Approaching the platform (3) to the reference position (7a) of the platform (3);

Coupling the manipulator (4) to the reference body (2); and

Actuation of the robot system in the coupled state, so that the reference configuration of the manipulator (4) is taken.

2. The method of claim 1, wherein the driving of the robot system in the coupled state further takes place such that the reference position (7a) of the mobile platform (3) is taken.

3. The method of claim 1 or 2, wherein in the coupled state, a mechanical and / or magnetic connection (8) between the manipulator

(4) and the reference body (2) is present.

4. The method according to any one of claims 1 to 3, wherein due to the approach of the platform (3) to the reference position (7 a) of the platform (3) a

Intermediate position (7b) of the platform (3) is reached, which is different from the reference position (7a) of the platform (3).

5. The method according to any one of claims 1 to 4, further comprising detecting acting on the robot system forces and moments, and wherein the robot system and preferably the manipulator (4) by means of a

Force control, in particular compliance control, is operated using the detected forces and moments, during the approach of the platform (3) and / or during the Koppeins of the manipulator (4).

6. The method according to any one of claims 1 to 5, wherein the coupling of the manipulator (4) to the reference body (2) comprises a frictional coupling, and wherein due to the Koppeins preferably a frictional connection (8) between the manipulator (4) and the Reference body (2) is present.

7. The method according to any one of claims 1 to 6, wherein the coupling of the manipulator (4) to the reference body (2) comprises a positive coupling, and wherein due to the Koppeins preferably a positive connection (8) between the manipulator (4) and the Reference body (2) is present.

8. The method according to any one of claims 1 to 7, wherein the coupling of the manipulator (4) to the reference body (2) takes place such that a

Coupling device (5, 6) of the manipulator (4) and preferably an end effector (5) of the manipulator (4) in a predefined orientation relative to the reference body (2).

9. The method of claim 8, wherein the coupling of the manipulator (4) to the reference body (2) takes place such that a coding of the

Coupling device (5, 6) of the manipulator (4) with a corresponding counter-coding of the reference body (2) coupled.

10. The method according to one of claims 1 to 9, wherein the provision of the reference position (7a) of the platform (3) and the reference configuration of the manipulator (4) comprises the following steps:

Moving the mobile platform (3) to a position in which the

Manipulator (4) can reach the reference body (2);

Coupling the manipulator (4) to the reference body (2); and

Detecting the position as the reference position (7 a) of the platform (3) and the configuration of the manipulator (4) in the coupled state as the

Reference configuration of the manipulator (4).

A robotic system comprising a manipulator (4), a mobile platform (3) supporting the manipulator (4), and a controller arranged to perform a method according to any of the steps 1 to 10 for controlling the manipulator (4)

Robot system perform.

12. Robot system according to claim 11, further comprising sensors for detecting forces acting on the robot system and in particular on the manipulator (4) forces and moments.

13. The method according to any one of claims 1 to 10 or robot system according to claim 11 or 12, wherein the manipulator (4) is a multi-axis

Articulated robot is.