Path planning method for a coating system and corresponding path planning system

Abstract

The invention relates to a path planning method for planning a movement path which is intended to be travelled by an applicator relative to a component to be coated, in particular when coating a motor vehicle body component with a paint, an adhesive or a sealing means, comprising the following steps: defining the movement path of the applicator, defining a plurality of measurement points on the actual component and measuring the spatial positions of the measurement points on the actual component, and correcting the movement path on the basis of the measured spatial positions of the measurement points on the actual component. The invention provides the following steps for correcting the movement path: coupling the movement path to a specified grid model of the component having a multiplicity of grid points, and adapting the grid model in accordance with the measured spatial positions of the measurement points on the actual component such that, together with the grid points of the grid model, the movement path coupled thereto is also adapted. The invention further comprises a corresponding path planning system for carrying out the path planning method according to the invention.

Description

[0001] DESCRIPTION

[0002] Path planning procedure for a coating system and corresponding path planning system

[0003] Technical field of the invention

[0004] The invention relates to a path planning method for planning a movement path to be followed by an applicator (e.g., rotary atomizer, print head) relative to a component to be coated (e.g., a motor vehicle body component), particularly when coating a motor vehicle body component with a paint, an adhesive, or a sealant. Furthermore, the invention relates to a correspondingly designed path planning system and a coating system with such a path planning system.

[0005] Background of the invention

[0006] In modern painting systems for painting motor vehicle body components, rotary atomizers are typically used as application devices. These are guided by a multi-axis painting robot along a predetermined painting path over the motor vehicle body component to be painted. The painting path to be followed by the rotary atomizer relative to the motor vehicle body component to be painted is determined according to the geometry of the motor vehicle body component to be painted, a process also referred to as "teaching." During painting, parallel paint paths are typically applied, overlapping laterally to form a continuous paint film on the motor vehicle body component.The requirements for the positioning accuracy of the rotary atomizer along the parallel paint paths are relatively low, since rotary atomizers emit a spray jet that is not spatially sharply defined, so that rotary atomizers are forgiving in terms of positioning accuracy.

[0007] More recently, however, so-called print heads have also been used as application devices. Unlike rotary atomizers, these print heads do not emit a spray jet, but rather a spatially defined paint jet, resulting in a sharply defined paint line on the component to be painted. When using such print heads, the requirements for the positioning accuracy of the applied paint lines are therefore significantly higher than when using rotary atomizers, since print heads are less forgiving in terms of positioning accuracy.

[0008] The problem here is that, in practice, the actual geometry of the vehicle body components to be painted exhibits slight deviations from the model-based geometry. Furthermore, it must be considered that the vehicle body components to be painted are usually transported through the paint booth by a conveyor, which also has a positioning inaccuracy. Further inaccuracies can arise from the robots commonly used and from temperature influences.

[0009] DE 10 2019 111 760 A1 therefore discloses a path planning method for a paint shop in which the geometry of the actual motor vehicle body component is measured in the paint booth in order to adjust the paint path accordingly. Individual measuring points are defined on the motor vehicle body component to be painted and their spatial position is then measured by a sensor. The paint path is then adjusted according to the measured position of the measuring points.

[0010] This well-known path planning method works relatively well for approximately rectangular surfaces, such as roof surfaces or hoods of vehicle body components. However, vehicle body components also have complex surfaces that are not approximately rectangular, such as fenders. Even with the well-known path planning method, there is still room for improvement when painting such curved and non-rectangular surfaces.

[0011] Description of the invention

[0012] The invention is therefore based on the object of improving the known path planning method described above, in particular to achieve better results when painting surfaces that are not approximately rectangular.

[0013] This problem is solved by a path planning method according to the main claim.

[0014] The path planning method according to the invention generally serves to plan a movement path that is to be traversed by an applicator relative to a component to be coated. The invention is therefore not limited to the planning of a painting path that is to be traversed by a print head relative to a motor vehicle body component. Rather, the invention is also suitable for planning a movement path that is to be traversed by an applicator that applies a different coating agent, such as an adhesive or a sealant. The invention is therefore not limited to paint with regard to the coating agent to be applied, but also encompasses other coating agents. Furthermore, the invention is not limited to motor vehicle body components with regard to the components to be coated, but can in principle also be implemented for the coating of other types of components.

[0015] The path planning method according to the invention initially provides, in accordance with the prior art, that a movement path of the applicator is defined, namely relative to the component to be coated later.

[0016] Furthermore, the path planning method according to the invention, in accordance with the prior art, also provides that several measuring points are defined on the real component, wherein the spatial position of the measuring points on the real component is then measured, for which purpose a sensor can be used.

[0017] The path planning method according to the invention also provides that the movement path is corrected on the basis of the measured spatial positions of the measuring points on the real component in order to later achieve the best possible coating result.

[0018] The invention now provides that the component to be coated is specified in the form of a grid model with a large number of grid points, wherein the movement path is coupled to the grid model. Furthermore, the path planning method according to the invention provides that the grid model is adapted as a function of the measured spatial positions of the measuring points on the real component, so that together with the grid points of the grid model, the movement path coupled to it is also adapted. A special feature of the invention therefore lies first in the coupling of the movement path to the grid model of the component, so that an adaptation of the grid model also leads to a corresponding adaptation of the movement path. A further special feature of the invention is that the grid model is adapted completely or almost completely according to the measured spatial positions of the measuring points on the real component.The adaptation of the grid model therefore preferably extends over all grid points, which are shifted according to the measured spatial positions of the measuring points on the real component.

[0019] The aforementioned adaptation of the mesh model according to the measured spatial positions of the measurement points on the real component is preferably carried out using at least one known mathematical method for deforming or distorting surfaces or computer-modeled objects. Such methods are described, for example, in an article in the Journal of Physical Mathematics 7(2) entitled "Mesh Deformation Approaches - A Survey" by Mohamed Selim and Roy Koomullil (DOI: 10.4172 / 2090-0902.1000181). Another preferred option for adapting the mesh model according to the measured spatial positions of the measurement points on the real component is a so-called Laplacian mesh processing algorithm, which can be derived from the publication by Olga Sorkine: "Laplacian Mesh Processing," EUROGRAPHICS 2005 (DOI: 10.2312 / egst.20051044).

[0020] It should be noted that the mesh model adjustment is preferably carried out across a large portion of the mesh model, or even across the entire mesh model of the component to be coated. This means that the position of a large portion of the mesh model's mesh points is changed during the adjustment. For example, at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or even at least 90% of all mesh points can be moved during this adjustment.

[0021] It should also be noted that when adapting the grid model, the measured positions of the measurement points are defined as fixed points of the grid model, while the positions of the remaining grid points of the grid model are adapted, in particular, smoothly and / or interpolated. For example, if a corner point of a wheel cutout of a fender of a motor vehicle body component is defined as the measurement point and the spatial position of this measurement point is determined completely (i.e., in all spatial directions), the corresponding grid point of the associated grid model is not adapted but defined as a fixed point.

[0022] Furthermore, it should be noted that the number of measurement points is preferably significantly smaller than the number of grid points in the grid model. For example, the number of measurement points can be smaller than 5%, 1%, 5%, or 1% of the number of grid points in the grid model. Thus, the number of measurement points can be smaller than 500, 200, 100, 50, 20, 10, or 5.

[0023] It has already been mentioned above that the predefined grid model of the component to be coated can have a large number of grid points that are located not only on the surface of the component, but also within the component. Due to the large number of grid points, the adaptation of the grid model according to the invention described above requires considerable computational effort. To reduce the required computational effort, the invention can provide for converting the predefined grid model into a simplified grid model by only taking into account the grid points on the surface of the component, while ignoring the grid points within the component. The adaptation of the grid model is then carried out on the basis of the simplified grid model, which has a reduced number of grid points and can therefore be adapted with less computational effort.

[0024] As already explained above, the spatial position of the measurement points on the real component is measured using a sensor. In practice, however, such sensors often cannot accurately determine the spatial position of the measurement points in all three spatial directions, so that measurement using a sensor does not provide position information in at least one spatial direction. When adapting the grid model, the measurement points are then defined as fixed points only with respect to the spatial directions in which the sensor provides position information, while the fixed points of the grid model can be shifted in at least one spatial direction in which the sensor does not provide position information.For example, if a measuring point is located on a roof edge of a motor vehicle body component and the sensor is a distance sensor that measures the measuring point at right angles to the roof edge, the sensor does not provide any position information along the roof edge, so that the corresponding grid point can then be moved along the roof edge when adapting the grid model.

[0025] It's also worth mentioning that the path planning process can be performed either within a coating system or outside of a coating system, for example, in the body shop of an automobile factory. Therefore, the measurement of the component to be coated does not necessarily have to take place in the paint booth, where the component will subsequently be painted.

[0026] Above, the path planning method according to the invention was initially described without coating the component. However, the invention also encompasses a coating method which first provides for the implementation of the path planning method and then the coating of the component according to the determined movement path. It should be noted here that the relative movement of the applicator relative to the component to be coated can occur in various ways. In one variant of the invention, the component to be coated is stationary during coating, while the applicator (e.g. print head) is moved along the movement path by a manipulator (e.g. painting robot). Another variant of the invention, however, provides that the applicator is stationary and the component to be coated is moved by the manipulator along the movement path relative to the stationary applicator.A further variant of the invention provides that both the applicator and the component to be coated are moved during the relative movement.

[0027] The aforementioned manipulator is preferably a coating robot, such as an articulated-arm robot with multiple movable axes, wherein the articulated-arm robot is optionally movable on a linear axis. Alternatively, however, it is also possible for the coating robot to have parallel kinematics, although this is less common. Furthermore, it is also possible for the manipulator not to be a robot in the strict sense, but rather a motion automaton with at least one linear axis. Such motion automatons are known per se in painting systems and are also referred to there as roof machines (i.e. with a horizontal linear axis) or side machines (i.e. with a vertical linear axis).

[0028] It has already been mentioned above that the path planning method according to the invention can also be carried out outside of a coating system in a measuring station of an automobile factory, for example, in the body shop of the automobile factory. The component is then subsequently coated in the coating system of the automobile factory, for example, in a paint booth. The coating path determined as part of the path planning method can then be transferred from the measuring station to the coating system, preferably with a fixed assignment to the respective component.

[0029] Alternatively, it is also possible for the path planning process and the actual coating process to be carried out in the same coating station (e.g. paint booth).

[0030] The sensor already mentioned above for measuring the component to be coated can be attached to the manipulator, which also moves the applicator during coating. In this case, the sensor is moved together with the applicator by the manipulator. The invention is particularly advantageous when using applicators (e.g. print heads) that are essentially overspray-free and emit a spatially narrowly defined jet of coating agent, in particular with a deposition efficiency of at least 80%, 90%, 95% or 99%. When using such applicators, the requirements for the positioning accuracy of the applicator and the trajectory accuracy of the determined movement path are significantly higher than when using atomizers. However, with regard to the type of applicator, the invention is not limited to print heads, but can in principle also be implemented with atomizers (e.g. rotary atomizers).

[0031] Furthermore, it should be mentioned that the invention also comprises a path planning system which is suitable for carrying out the path planning method according to the invention.

[0032] For this purpose, the path planning system according to the invention initially comprises a manipulator, which may, for example, be a multi-axis coating robot.

[0033] In addition, the path planning system according to the invention comprises a sensor for spatial measurement of the component to be coated.

[0034] Furthermore, the path planning system according to the invention comprises a control unit for controlling the manipulator and querying the sensor. The control unit is designed to control the manipulator and query the sensor in such a way that the path planning system executes the path planning method according to the invention and / or the coating method according to the invention.

[0035] The robot, manipulator, and sensor are preferably arranged together within a paint shop of an automobile factory. For example, the sensor can also be moved by the manipulator together with the applicator, as briefly mentioned above.

[0036] Regarding the sensor, it should be mentioned that the sensor can include, for example, a light section sensor, a camera and / or a lighting unit.

[0037] Other advantageous developments of the invention are characterized in the subclaims or are explained in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0038] Brief description of the drawings

[0039] Figure 1 shows a schematic representation of the path planning method according to the invention.

[0040] Figure 2 shows a detailed representation of the adaptation of the grid model according to the spatial positions of the measurement points.

[0041] Figure 3 shows a schematic representation for simplifying a grid model of a motor vehicle body component to reduce the computational effort when adapting the grid model.

[0042] Figure 4A shows a highly simplified schematic representation of a coating system according to the invention, which enables the implementation of the path planning method according to the invention.

[0043] Figure 4B shows an enlarged detail view of Figure 4A.

[0044] Detailed description of the drawings

[0045] The embodiment shown in Figure 1 is now described below.

[0046] In a step S1, a grid model of the motor vehicle body component to be painted is first specified, whereby the grid model can be provided, for example, by a CAD system (CAD: Computer Aided Design).

[0047] In addition, measurement points are defined on the real component, with the reference position of these measurement points being known, for example, from the grid model according to step S1. The spatial position of these measurement points is then measured by a sensor, and the difference between the measured spatial position of the measurement points and the specified reference position of the measurement points is determined in step S2.

[0048] These deviations between the measured spatial positions and the reference positions are then used in step S3 to adapt the specified mesh model. This adaptation of the mesh model in step S3 is performed according to the well-known "Laplacian Mesh Processing," as described in Olga Sorkine's publication "Laplacian Mesh Processing," EUROGRAPHICS 2005. The details of this adaptation are described in more detail below with reference to the detailed illustration in Figure 2.

[0049] The given grid model is then used together with a predefined trajectory in a step S4 to assign sections of the trajectory to the grid model.

[0050] The assigned path segments and the corresponding segments of the grid model are then used in step S5 together with the adjusted grid model to adjust the trajectory. It should be noted that the trajectory is coupled to the grid model, so that adjusting the grid model in step S3 also leads to a corresponding adjustment of the trajectory.

[0051] The following describes the detailed representation according to Figure 2, which illustrates the adaptation of the grid model.

[0052] In a step S3.1, the given, not yet adapted mesh model of the component is adopted and then transformed into a representation that describes a local geometry, which is done by the so-called "Laplacian operator and differential surface representation", which is described in section 2 of the above-mentioned publication "Laplacian Mesh Processing".

[0053] In the following step S3.2, the displacement values ​​at the measurement points are then taken into account, i.e., the deviations between the reference positions of the measurement points on the one hand and the measured spatial positions of the measurement points on the other. The mesh model is then reconstructed so that displacements at the measurement points and the local geometry are maintained as closely as possible. This essentially corresponds to the so-called "mesh editing and shape interpolation," which is described in Section 4 of the aforementioned publication "Laplacian Mesh Processing."

[0054] Figure 3 shows, on the left, a complex grid model 1 of a motor vehicle body component to be painted, with a large number of grid points, which would require a high computational effort when adapting the grid model 1 according to the invention. The complex grid model 1 is therefore converted into a simplified grid model 2, which contains a significantly smaller number of grid points and therefore requires a significantly lower computational effort when adapting the grid model 2 according to the invention.

[0055] Figures 4A and 4B show a highly simplified schematic representation of a painting system according to the invention with a multi-axis painting robot 3 that can guide a print head 4 over a motor vehicle body component 5 in order to paint the motor vehicle body component 5. Furthermore, the painting robot 3 also guides a sensor 6 together with the print head 4 over the motor vehicle body component 5 in order to measure the spatial position of measuring points on the motor vehicle body component 5.

[0056] The sensor 6 and the painting robot 3 are connected to a robot controller 7, which controls the painting robot 3 and queries the sensor 6. The robot controller 7 contains a program that, in one embodiment, executes the path planning method according to the invention.

[0057] The invention is not limited to the preferred embodiment described above. Rather, the invention also encompasses variants and modifications that also utilize the inventive concept and fall within the scope of protection. In particular, the invention also claims protection for the subject matter and features of the subclaims, independently of the respective claims referred to, and in particular even without the features of the main claim. The invention thus encompasses various aspects of the invention that enjoy independent protection.

[0058] Advantages of the invention

[0059] The path planning method according to the invention is particularly advantageous for path planning on complex surfaces, such as fenders or vehicle body components with a roof cutout. The positioning of the path points of the adapted coating path is significantly more precise. Displacement components in directions that cannot be measured by the sensor (e.g., along an edge) are also not included in the displacement or distortion of the grid model.

[0060] List of reference symbols

[0061] 1 Complex lattice model

[0062] 2 Simplified grid model 3 Painting robot

[0063] 4 Print head

[0064] 5 Motor vehicle body component

[0065] 6 Sensor 7 Robot control

Claims

CLAIMS 1. A path planning method for planning a movement path to be followed by an applicator (4) relative to a component (5) to be coated, in particular when coating a motor vehicle body component (5) with a paint, an adhesive, or a sealant, comprising the following steps: a) defining the movement path of the applicator (4), b) defining a plurality of measuring points on the real component (5) and measuring the spatial positions of the measuring points on the real component (5), and c) correcting the movement path based on the measured spatial positions of the measuring points on the real component (5), characterized by the following steps for correcting the movement path: d) coupling the movement path to a predetermined grid model (1, 2) of the component (5) having a plurality of grid points, and e) adapting the grid model (1, 2) according to the measured spatial positions of the measuring points on the real component (5),so that together with the grid points of the grid model (1, 2) the coupled trajectory is also adapted., 2. Path planning method according to claim 1, characterized in that a) the adaptation of the grid model (1, 2) of the component (5) is carried out according to the Laplacian mesh processing algorithm, and / or b) the adaptation of the grid model (1, 2) is carried out distributed over a large part of the grid model (1, 2), in particular over at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% of all grid points of the grid model (1, 2), and / or c) that during the adaptation of the grid model (1, 2), the measured positions of the measuring points are defined as fixed points of the grid model (1, 2), while the positions of the remaining grid points of the grid model (1, 2) are adapted, in particular in a sliding and / or interpolating manner, and / or d) that the number of measuring points is significantly smaller than the number of grid points of the grid model (1, 2), in particular less than 5%, 1%, 5%o or 1%o of the number of grid points of the grid model (1, 2),and / or e) that the number of measuring points is less than 500, 200, 100, 50, 20, 10 or 5., 3. Path planning method according to one of the preceding claims, characterized in that a) the predetermined grid model (1) not only comprises grid points on the surface of the component (5) but also grid points within the component (5), b) that the given grid model (1) is converted into a simplified grid model (2) by taking only the grid points on the surface of the component (5) into account, and c) that the simplified grid model (2) is adapted according to the measured positions of the measuring points.

4. Path planning method according to one of the preceding claims, characterized in that a) the spatial position of the measuring points on the real component (5) is determined by means of a sensor (6) is measured, b) that the sensor (6) does not measure the spatial position of the measuring points on the real component (5) in all spatial directions, but does not provide any position information in at least one spatial direction, c) that when adapting the grid model (1, 2) the measured spatial positions of the measuring points are defined as fixed points of the grid model (1, 2), while the remaining grid points of the grid model (1, 2) are adapted, d) that the spatial position of the fixed points of the grid model (1, 2) is only fixed in the spatial directions in which the sensor (6) provides position information, and e) that when adapting the grid model (1, 2) the fixed points of the grid model (1, 2) are displaceable in the at least one spatial direction in which the sensor (6) does not provide any position information.

5. Path planning method according to one of the preceding claims, characterized in that the path planning method is carried out outside a coating plant, in particular in the body shop of an automobile factory.

6. Coating method for coating a component (5), in particular a motor vehicle body component (5), with a coating agent, in particular with a paint, an adhesive or a sealing agent, with the following steps: a) Carrying out the path planning method according to one of the preceding claims for Determination of the movement path, and b) relative movement of an applicator (4) by means of a manipulator (3) along the defined movement path relative to the component (5) and coating of the component (5) by the applicator (4).

7. Coating method according to claim 6, characterized in that a) during the relative movement the component (5) to be coated is stationary and the applicator (4) is moved by the manipulator (3) along the movement path, or b) that during the relative movement the applicator (4) is stationary and the component to be coated (5) is moved by the manipulator (3) along the movement path, or c) that during the relative movement the applicator (4) is moved by the manipulator (3) and the component (5) to be coated is also moved.

8. Coating method according to one of claims 6 to 7, characterized in that a) that the manipulator (3) is a coating robot (3), in particular a1) a coating robot (3) as an articulated arm robot with several movable axes, wherein the articulated arm robot is optionally movable on a linear axis, a2) a coating robot (3) with parallel kinematics, or b) that the manipulator (3) is a movement machine with at least one linear axis, in particular as a roof machine or side machine.

9. Coating method according to one of claims 6 to 8, characterized in that a) the path planning method is carried out at least partially outside a coating system in a measuring station of an automobile plant, in particular in the body shop of the automobile plant, and b) that the coating of the component (5) is subsequently carried out in the coating system of the automobile plant.

10. Coating method according to claim 9, characterized in that the adapted grid model (1, 2) and / or the adapted coating path are transferred from the measuring station to the coating system in a fixed assignment to the respective component (5).

11. Coating method according to one of claims 6 to 8, characterized in that the path planning method is carried out in a coating plant of an automobile factory in which the coating of the component (5) also takes place.

12. Coating method according to claim 11, characterized in that the sensor (6) for measuring the component (5) to be coated is attached to the manipulator (3) and is moved by the manipulator (3) together with the applicator (4) along the movement path.

13. Coating method according to one of claims 6 to 12, characterized in that a) that the applicator (4) is a substantially overspray-free applicator (4) which, in contrast to an atomizer, does not atomize the coating agent but emits a spatially narrowly limited coating agent jet, in particular a print head, in particular with an application efficiency of at least 80%, 90%, 95% or 99%, or b) that the applicator (4) is an atomizer, in particular a rotary atomizer.

14. Path planning system for planning a movement path to be followed by an applicator (4) guided by a manipulator (3) during a coating of a component (5), in particular for a coating of a motor vehicle body component (5) with a paint, an adhesive or a sealant, with a) a manipulator (3), in particular a multi-axis coating robot (3), b) a sensor (6) for spatially measuring the component (5) to be coated, and c) a control unit (7) for controlling the manipulator (3) and for querying the sensor (6), characterized in that d) that the control unit (7) controls the manipulator (3) and queries the sensor (6) in such a way that the path planning system carries out the path planning method according to one of claims 1 to 5 and / or carries out the coating method according to one of claims 6 to 13.

15. Path planning system according to claim 14, characterized in that the manipulator (3) and the sensor (6) for measuring the component (5) to be coated are arranged within a painting system of an automobile factory or in the body shop of an automobile factory.

16. Coating system according to claim 14 or 15, characterized in that the sensor (6) for measuring the component (5) is mounted on the manipulator (3) and is moved by the manipulator (3) together with the applicator (4) over the surface of the component (5) to be coated.

17. Coating system according to one of claims 14 to 16, characterized in that a) the sensor (6) has the following: a1) a light section sensor and / or a2) a camera and / or a3) a lighting unit, b) the applicator (4) b1) is an atomizer, in particular a rotary atomizer, or b2) is a substantially overspray-free applicator (4) which, in contrast to an atomizer, does not atomize the coating agent, but rather emits a spatially narrowly limited coating agent jet, and / or c) the coating agent is a paint, an adhesive, or a sealant, and / or d) the component (5) to be coated is a motor vehicle body component (5), and / or e) the manipulator (3) is a coating robot (3), in particular e1) a coating robot (3) as an articulated-arm robot with several movable axes, wherein the articulated-arm robot is optionally movable on a linear axis is,e2) a coating robot (3) with parallel kinematics, or f) that the manipulator (3) is a motion machine with at least one linear axis, in particular as a roof machine or side machine.,

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