A method for automatically painting a surface and a painting robot system

Abstract

The present invention relates to a method (100) for painting a surface (50) of an object using a robot system (1), the robot system comprising a painting head (11), wherein the painting head comprises a nozzle arrangement (14) with a set of nozzles (16) for depositing paint (30) and a surface measuring system (18) configured to detect the surface, wherein the method comprises: controlling (110) the surface measuring system to detect a presence of the surface within a predefined range (29); and responsive to the detected presence of the surface, controlling (130) the nozzle arrangement to deposit paint at the detected surface.

Description

[0001] A METHOD FOR AUTOMATICALLY PAINTING A SURFACE AND

[0002] A PAINTING ROBOT SYSTEM

[0003] Technical Field

[0004] The present invention relates to the field of automated painting by means of a robot-carried paint nozzle. By way of example, the present invention relates to methods, controllers and robot systems for painting and controlling the painting of a surface of an object, such as a two-dimensional (2D) or a three- dimensional (3D) object. In particular, the present invention relates to methods and systems for automatic painting on an external surface or an internal surface of a vehicle or the like.

[0005] Background

[0006] The painting of complex surfaces, such as three-dimensional (3D) exterior surfaces of vehicles, e.g. surfaces of cars, airplanes, and underwater vessels, often requires precise application of paint to achieve desired aesthetic outcomes. With the advent of robotic systems, there has been an increasing emphasis on automating the painting process, which typically involves complex planning and painting sequences based on various data. Despite advances in the field, there remains a need for further improvements in automating the process, particularly for enhanced color painting on interior and exterior surfaces of 3D objects, such as the interior and exterior surfaces of vehicles.

[0007] Summary

[0008] In view of the above, it would be desirable to provide an improved method for painting on a surface using a robot system with a surface measuring system and a nozzle arrangement, where the paint can be applied in a more direct and automated manner. The object is at least partly achieved by a computer- implemented method according to independent claim 1, and the present invention as defined in the other independent claims. The dependent claims relate to advantageous embodiments.

[0009] According to a first aspect of the present invention, there is provided a method for painting a surface of an object using a robot system. The robot system comprises a painting head. The painting head has a nozzle arrangement with a set of nozzles for depositing paint and a surface measuring system configured to detect the surface. The method comprises controlling the surface measuring system to detect a presence of the surface within a predefined range; and responsive to the detected presence of the surface, controlling the nozzle arrangement to deposit paint at the detected surface.

[0010] The method is typically executed by a controller having processing circuitry. As such, in one example, the method is a computer-implemented method.

[0011] Hereby, there is provided an improved method for painting at least a region of the surface of an object, such as a three-dimensional (3D) object, wherein the surface measuring system detects the presence of the surface within a predefined range. The predefined range represents an operational threshold, i.e. an operational window within which the painting head can detect the surface and apply paint accurately (e.g. 2-7 mm). As such, while the actual distance between the painting head and the surface may vary as the painting head moves over the object, the proposed method and system may be configured only to activate paint deposition when the surface is within the predefined range. The proposed method and system automatically enable the nozzles in real time based on feedback from the surface measuring system, while accounting for any delay corresponding to the offset between the position of the nozzles and the surface measuring system, as well as the speed of the painting head. In this manner, it becomes possible to eliminate, or at least reduce, the need for complex image processing and comparing the scanned data to known geometries, enabling a more efficient and adaptable painting process for various painting tasks. The proposed method contrasts with prior art methods and systems, where the paint application typically relies on advanced image processing techniques and pre-existing knowledge of surface geometry. More specifically, the invention is at least partly based on the insight that prior art methods typically require the system to process the scanned surface data, compare it to known geometry, and then determine the appropriate nozzle control actions. Such process is resource-intensive and less suited to flexible or ad-hoc painting tasks, especially when the geometry of the surface is not known in advance.

[0012] The proposed method addresses challenges associated with automatic painting of surfaces by providing a painting head having both nozzles for depositing paint and a surface measuring system, allowing for automatic surface detection using the surface measuring system followed by an instantaneous activation of the nozzles, driven by real-time feedback from the surface measuring system.

[0013] More specifically, the method uses real-time feedback from the surface measuring system, allowing the nozzles to be activated as soon as the surface is detected within the predefined range. A technical advantage may include eliminating, or at least reducing delays associated with processing of image data, while ensuring that paint is deposited only on areas within the correct range, leading to a more precise paint application.

[0014] The invention provides methods and systems configured to operate independently of any preloaded geometric data. By not requiring the comparison of scanned data to known geometry, the invention allows for more robust and adaptable painting of random or unknown objects, such as boxes or other irregular surfaces. As such, the methods and systems maybe particularly useful for stand-alone applications where surface geometry may be unknown or irregular. For example, the painting head could be moved over a random object and still function effectively without prior knowledge of the surface. As the method and system rely less on pre-programmed geometry, the invention also offers a less complex solution for painting tasks. The absence of detailed geometric data or image processing allows the methods and systems to be quickly deployed in various environments, offering cost-effective and time-saving advantages, especially for smaller- scale or one-off projects.

[0015] By the arrangement and configuration of the painting head, the surface measuring system is operated to continuously update the surface profile information, and the nozzle arrangement is dynamically controlled to account for variations in the surface during the painting process.

[0016] Flexibility in application may make the method suitable for a wide range of industrial uses, from detailed graphics to large surface color applications.

[0017] To this end, the proposed method allows for a more versatile, responsive, and adaptable process of painting on 3D surfaces, contributing to improved overall performance in automated painting systems.

[0018] The surface maybe a surface of a 2D object or a 3D object. For example, the surface maybe any one of an interior and exterior surface of an 3D object. Examples of 3D objects are vehicles, e.g. a car, an airplane, an underwater vessel and the like. The surface defines a part of a surface of the 3D object, or the complete surface of the 3D object.

[0019] Typically, the predefined range corresponds to an operational threshold for controlling paint deposition.

[0020] The provision of controlling the surface measuring system to detect a presence of a surface within a predefined range may comprise measuring surface geometry of the surface and determining the surface profile based on the measured surface geometry. A technical advantage may include providing a more detailed understanding of surface geometry, enabling accurate paint application by ensuring the system can handle complex surfaces with greater precision.

[0021] The surface measuring system and the nozzle arrangement may be operatively coupled to perform surface detection and paint deposition in real time during a single operational pass. A technical advantage may include enabling an even more direct activation of the nozzles in response to real- time surface detection by the surface measuring system, creating a closed- loop system where data is immediately used to control the paint deposition. By reducing, or even eliminating the need for complex image generation and alignment, the system can be made less complex, allowing for a more responsive and efficient operation. The method thus enables immediate application of paint to the surface as soon as the surface is detected, improving efficiency compared to prior art methods. Prior art systems often require scanning, mapping, and image generation before painting. In contrast, the method performs paint deposition on-the-fly, relying purely on real-time data from the surface measuring system. Such feature makes the method particularly useful for flexible applications, where the painting unit can be moved over a surface and apply paint immediately as the surface is detected. Another technical advantage may include increasing operational efficiency by performing surface detection and paint deposition simultaneously in real time, reducing overall process time and improving throughput in industrial applications.

[0022] The detected surface data from the surface measuring system may be directly processed to control the corresponding paint deposition by the nozzle arrangement. A technical advantage may include reducing delays by processing surface data directly for nozzle control, resulting in more responsive paint deposition and minimizing risks of misalignment during the painting process.

[0023] Typically, controlling the nozzle arrangement to deposit paint at the detected surface comprises controlling the nozzle arrangement to deposit paint only from those nozzles that are positioned above the detected surface.

[0024] The provision of controlling the nozzle arrangement to deposit paint maybe performed on-the-fly without generating a complete image of the surface prior to the initiation of painting of the surface. A technical advantage may include enabling faster setup and operation by eliminating the need to pre- process a complete surface image. The system dynamically adapts to the surface geometry as the painting progresses, which enhances flexibility for various tasks.

[0025] The method may further comprise storing data indicative of the detected presence of the surface within the predefined range in a temporary buffer memory, and controlling the nozzle arrangement based on the data stored in the temporary buffer memory as the painting head moves over the surface. A technical advantage may include improving synchronization between surface detection and paint deposition. Temporary data storage allows for smooth operation even if there is a slight delay between detection and paint application, maintaining accuracy as the painting head moves.

[0026] The actuation of the nozzle arrangement maybe based solely on measurement data provided by the surface measuring system. A technical advantage may include providing a less complex control system by relying exclusively on data from the surface measuring system. Thus, the system becomes more streamlined and less prone to errors arising from multiple input sources.

[0027] Byway of example, the predefined range maybe a predetermined distance range of 0.5 to 15.0 mm. Preferably, the predefined range maybe a predetermined distance range of 1.0 to 10 mm. Still preferably, the predefined range is a predetermined distance range of 2.0 to 7.0 mm.

[0028] The predefined range may serve as a binary control for actuation of the nozzle arrangement, such that the nozzles are activated to deposit paint when the painting head is within the predefined range relative to the surface, and paint deposition is halted when the surface is outside the predefined range. A technical advantage may include improving control over paint application by using a binary condition for nozzle activation. Paint is only deposited when the surface is within the range, helping to reduce wastage and enhance paint quality. In one example, the method may further comprise generating an image data matrix indicative of one or more paintable areas of the surface based on the detected presence of the surface.

[0029] In the example when the method comprises generating an image data matrix indicative of one or more paintable areas of the surface based on the detected presence of the surface, the method may further control the nozzle arrangement to deposit paint on one or more regions of the surface corresponding to one or more paintable areas. As such, in one example, the method may further comprise generating an image data matrix indicative of one or more paintable areas of the surface based on the detected presence of the surface; and responsive to the detected presence of the surface and based on the generated image data matrix, controlling the nozzle arrangement to deposit paint on one or more regions of the surface corresponding to one or more paintable areas. As such, controlling the nozzle arrangement to deposit paint at the detected surface may comprise controlling, responsive to the detected presence of the surface and based on the generated image data matrix, the nozzle arrangement to deposit paint on one or more regions of the surface corresponding to one or more paintable areas.

[0030] The generated image data matrix may comprise a binary coverage map. The binary coverage map indicates the paintable areas of the surface based on the detected presence of the surface within the predefined range. Moreover, paint is deposited uniformly on the paintable areas of the surface represented by the binary coverage map. A technical advantage may include achieving a more consistent paint application by using a binary coverage map that more clearly defines paintable areas, allowing for a more uniform paint deposition and streamlined decision-making process for the paint application.

[0031] The method may further comprise receiving a digital image containing one or more graphics details. In addition, the nozzle arrangement may further be controlled based on the received digital image. A technical advantage may include offering greater flexibility for complex painting tasks, such as applying detailed graphics or patterns. By integrating digital image data, the system can handle more intricate designs while maintaining the efficiency of the painting process.

[0032] The surface measuring system may be positioned to detect the surface immediately before the nozzle arrangement deposits paint on the surface. A technical advantage may include enhancing precision by positioning the surface measuring system to detect the surface just before the paint is applied. This approach reduces the potential for errors caused by surface movement or misalignment, ensuring more accurate paint deposition.

[0033] In one example, the surface measuring system is a spatial data acquisition device, including e.g. a 2D line scanner or a 3D scanner.

[0034] According to a second aspect of the invention, there is provided a controller comprising processing circuitry configured to execute the method of the first aspect of the invention. The second aspect of the invention may seek to solve the same problem as described for the first aspect of the invention. Thus, effects and features of the second aspect of the invention are largely analogous to those described above in connection with the first aspect of the invention. Another technical advantage may include greater integration and efficiency in executing the method, as a controller with dedicated processing circuitry ensures that the steps of the method are carried out effectively, leading to reliable and consistent performance in painting applications.

[0035] According to a third aspect of the invention, there is provided a robot system for painting a surface of a three-dimensional (3D) object. The robot system comprises a robot arm arrangement and a painting head configured to be connected to the robot arm arrangement. The painting head comprises a nozzle arrangement with a set of nozzles for depositing paint. The painting head further comprises a surface measuring system configured to detect the surface. In addition, the robot system comprises one or more controllers according to the second aspect of the invention. Typically, at least one of the controllers comprises processing circuitry configured to execute the method of the first aspect of the invention. The third aspect of the invention may seek to solve the same problem as described for the first and second aspects of the invention. Thus, effects and features of the third aspect of the invention are largely analogous to those described above in connection with the first and second aspects of the invention. An additional technical advantage may include enhanced automation and precision in the painting process, as the robot system is equipped with a controller that can execute the method.

[0036] The robot system maybe an industrial robot system and the controller may be an integral part of a robot control system configured to control the robot arm arrangement and the nozzle arrangement. Such a system may reduce the complexity of the overall system architecture, while ensuring synchronized operation of the robot arm arrangement and nozzle arrangement.

[0037] In one example, the surface measuring system may be arranged in a leading part of the painting head and the nozzle arrangement may be arranged in a trailing part of the painting head.

[0038] The surface measuring system may comprise a laser source and a camera. By way of example, the laser source is a laser sensor. Typically, the laser source of the surface measuring system is arranged at the leading part of the painting head and the nozzle arrangement of the painting head is arranged at the trailing part relative to the leading part.

[0039] In addition, the camera of the surface measuring system may be arranged at the leading part of the painting head. Moreover, the laser source may be arranged before the camera in the leading part.

[0040] There is also provided a computer program product comprising program code for performing, when executed by a controller, the method according to the first aspect, and a non-transitory computer-readable storage medium comprising instructions, which when executed by a controller, cause the controller to perform the method according to the first aspect. The computer program may be stored or distributed on a data carrier. As used herein, a “data carrier” may be a transitory data carrier, such as modulated electromagnetic or optical waves, or a non-transitory data carrier. Non- transitory data carriers include volatile and non-volatile memories, such as permanent and non-permanent storage media of magnetic, optical or solid- state type. Still within the scope of “data carrier”, such memories may be fixedly mounted or portable.

[0041] Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following description. The skilled person realize that different features of the present invention may be combined to create embodiments other than those described in the following, without departing from the scope of the present invention.

[0042] Brief Description of the Drawings

[0043] These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing example embodiments of the invention, wherein:

[0044] Fig. i schematically illustrates an example of a robot system according to the present invention;

[0045] Fig. 2 schematically illustrates an example of a painting head of the robot system, the painting head being configured to be operated by the robot system in Fig. i for painting a surface of a 3D object, according to the present invention;

[0046] Fig. 3 schematically illustrates an example of painting the surface of the 3D object, according to the present invention; and

[0047] Fig. 4 is a flow-chart of an example of a method for painting a surface of a 3D object, in which the painting is controlled and performed by the robot system of Figs. 1 to 3, according to the present invention.

[0048] Detailed Description

[0049] In the present detailed description, various embodiments of robot systems and methods are mainly described with reference to a robot system comprising an industrial robot. However, the described robot system is suitable for any type of system and arrangement comprising a robot, such as an industrial robot, a service robot and the like. Moreover, the described method, control system and controller may be suitable for remote operations in relation to the robot system. The same or similar reference numerals will be used to denote the same or similar structural features. For ease of reference, the examples are described in relation to a three-dimensional (3D) object in the form of the vehicle.

[0050] Turning now to Fig. 1, which schematically represents a first perspective side view of an exemplary robot system 1. In this example, the robot system 1 is an industrial robot system. The robot system 1 comprises at least one robot manipulator arrangement 10. In some robot systems 1, the robot system 1 may comprise a plurality of robot manipulator arrangements 10. The robot system 1 is here integrated into an automatic assembly line for vehicles 2, such as passenger cars. The robot system 1 is here also configured to perform painting of one or more parts and surfaces of the vehicle 2, as will be further described herein with reference to figures 1 to 4. As such, the robot system 1 is configured as an automated painting robot system.

[0051] The vehicle 2 is one example of a 3D object having interior and exterior surfaces 50. In Fig. 1, the surface 50 is an exterior surface in the form of a roof surface of the vehicle 2. The surface 50 may typically be an exterior surface of a vehicle 2, e.g. a car, an airplane, vessel, underwater vessel and the like. The surface 50 can extend over the entire part or component, or as illustrated in Fig. 1, over a defined region of a part or component, such as the roof surface of the vehicle 2. In other examples, the surface 50 may likewise be an interior surface of the 3D object, such as an interior surface of the vehicle 2. The automated painting robot system is adapted (e.g., as regards paint-cell size, arm dimensions) for industrial-scale painting, with an ability to paint one or more surfaces 50, where each surface has a spatial extent of at least 0.1 m, such as at least 0.5 m, such as at least 1.0 m, such as at least several meters, such as at least 10 m. With reference to Fig. 1, the robot manipulator arrangement io is arranged on a base 40, such as a frame. The base 40 is the foundation on which the robot manipulator arrangement 10 is mounted. The base 40 provides stability and is typically designed to allow for easy integration into existing production lines. The base 40 may be an integral part of the robot manipulator arrangement 10 or a separate part of the robot system 1.

[0052] The robot manipulator arrangement 10 of Fig. 1 comprises a robot arm arrangement 12. For example, the robot arm arrangement 12 is rotatably mounted on the base 40. The robot arm arrangement 12 comprises one or more robot arms 12a to 12c. In Fig. 1, the robot arm arrangement 12 comprises three robot arms, i.e. a first robot arm 12a, a second robot arm 12b, and a third robot arm 12c. The robot arms 12a, 12b, 12c of the robot arm arrangement 12 are mechanical units configured to replicate the motions of a human arm, allowing for a wide range of movements. Thus, each one of the robot arms 12a, 12b, 12c typically comprises one or more joints. As schematically depicted in Fig. 1, the robot arms 12a, 12b, 12c are articulated connected to each other via the joint(s). Moreover, the first robot arm 12a is rotatably arranged on the base 40. The joints provide a 360-degree range of motion, allowing the robot arms 12a, 12b, 12c to rotate, pivot, and move in multiple directions. Such articulation provides the robotic system 1 with flexibility and precision, allowing for complex manipulations in confined spaces. This level of articulation is particularly advantageous in surface treatment applications such as painting. The ability to maneuver seamlessly over complex surfaces provides even and consistent application, making the robot system 1 suitable for tasks that require high-quality finishes, such as automotive painting.

[0053] Moreover, as depicted in Fig. 1, the robot manipulator arrangement 10 comprises a painting head 11. The painting head 11 is configured to be connected to the robot arrangement 10. In this example, the painting head 11 is pivotably connected to the robot arm 12c of the robot arm arrangement 12. The painting head 11 is here connected to the robot arm arrangement 12 via a connection interface 13 disposed on the robot arm 12c. Hence, at least one of the robot arms comprises the connection interface 13 configured to connect the painting head 11 to the robot arm arrangement 12, as may be gleaned from e.g. Fig. 1. The painting head 11 is here the end effector of the robot manipulator arrangement 10. To this end, the robot system 1 is configured to move the painting head 11 over the various surfaces of the vehicle 2 through the robot arm arrangement 12.

[0054] As shown in Fig. 1, the painting head 11 comprises a nozzle arrangement 14. The nozzle arrangement 14 is an integral part of the painting head 11. As such, the nozzle arrangement 14 is movable over the surface 50 by the robot system 1. Through this configuration, the nozzle arrangement 14 is configured to move over the surface 50 in various directions by manipulation of the robot arm arrangement 12.

[0055] The paint 30 can be provided and supplied in several different ways. Typically, the paint 30 is a colorant. One type of colorant is ink. The paint 30 may also include, or constitute, a coating material or other surface deposition materials.

[0056] The nozzle arrangement 14 is here adapted for inkjet printing. One type of inkjet printing is so-called pixel printing, Inkjet printing, in the form of pixel printing, includes a two-dimensional matrix of individually controllable nozzles 16. Hence, the nozzle arrangement 14 here comprises multiple nozzles 16. Each nozzle 16 is configured to be controllable between an open state, in which paint 30 flows out from an outlet of the nozzle 16 upon a firing command from a controller, and a closed state. That is, each nozzle 16 can be controlled in a firing state and in a non-firing state. As such, each nozzle 16 is configured to deposit paint droplets. Accordingly, painting head 11 comprises the nozzle arrangement 14 having a set of nozzles 16 for depositing paint 30 on the surface 50 based on one or more commands from the controller(s) 90a, 90b of the robot system 1.

[0057] The paint 30 is supplied to the painting head 11 via a paint supply conduit arrangement 31, as shown in Fig 1. The paint supply conduit arrangement 31 is fluidly connected to the nozzle arrangement 14 and the nozzles 16. The paint supply conduit arrangement 31 is an integral part of the painting head 11 and the robot system 1. The paint supply conduit arrangement 31 is fluidly connected to a paint fluid reservoir (not shown), such as an ink fluid storage. The paint fluid reservoir can be arranged on the robot system 1 or external of the robot system 1.

[0058] It should be noted that the term “colorant” typically encompasses any substance used to impart color, including paint, inks, dyes, pigments, and other material. In implementations adapted for color image printing, the paint supply conduit arrangement 31 may include multiple paint supply lines corresponding to different basic colors of paint. The paint supply lines may be operationally independent, or they may share certain hardware components or control functionalities. Conversely, it is envisioned that one paint supply line maybe at the service of multiple paint nozzles.

[0059] As shown in e.g. Fig. 1, the painting head 11 with the nozzle arrangement 14 is adapted for movement in multiple directions indicated by the arrows.

[0060] Typically, the nozzle arrangement 14 through the movement of the painting head 11 is adapted to sweep a painting stroke that is y units wide. In practice, the width y is usually somewhat less than the outer dimensions of the nozzle arrangement 14. In a representative inkjet-printing use case, the number of individually controllable nozzles 16 may be of the order of one thousand, and the width y of the painting stroke may be of the order of 0.1 m. The paint density on the surface 50 is generally determined by the ratio of the number of firing nozzles 16 corresponding to the number of outlets of the nozzles 16 and the speed of movement of the painting head 11 (corresponding to the speed of the nozzle arrangement 14) relative to the surface 50. Controlling the nozzles 16 and paint density, including selecting color etc., can be performed in several different manners depending on type of painting and / or type of image, and type of surface.

[0061] One example of a painting head 11 is an ink-jet painting head. As such, the nozzle arrangement 14 is configured to deposit paint 30 in the form of ink. In one example, the deposited ink forms a painting layer on the surface 50. In other examples, the deposited ink forms an image on the surface 50. In FIG. 1 the paint on the surface 50 forms a painted stripe. The painted stripe defines a painter surface region 22 of the surface 50. Hence, the painted surface comprises the painted surface region 22.

[0062] Moreover, the painting head 11 comprises a surface measuring system 18, as illustrated in Fig. 1. The surface measuring system 18 is configured to measure spatial data of the surface 50. Accordingly, the surface measuring system 18 is a spatial data acquisition device. More specifically, the surface measuring system 18 is configured to measure the surface 50, and identify surface features in the measured geometry data. As such, the measured spatial data contains spatial data of the actual surface 50. By way of example, the surface measuring system 18 is here a scanner, such as a 3D scanner or a 2D line scanner. As illustrated in Fig. 1, the surface measuring system 18 is an integral part of the painting head 11. As the surface measuring system 18 is an integral part of the painting head 11, the surface measuring system 18 is configured to be moved over the surface 50 through the robot arm arrangement 12 in a similar manner as the nozzle arrangement 14. To this end, the surface measuring system 18 is comprised in the painting head 11. Some parts of the surface measuring system 18 may in some examples be at least partly arranged in, or be an integral part of, the robot manipulator arrangement, or in another robot manipulator arrangement.

[0063] The surface measuring system 18 is configured to detect the presence of the surface 50. For example, the surface measuring system 18 is configured to perform laser triangulation. Thus, the surface measuring system 18 here comprises a laser source 19 and a camera 20. The laser source is provided in the form of a laser sensor. Moreover, the laser source 19 comprises a projection lens, while the camera comprises a collecting lens. The laser source and the camera are arranged with a base line 24, as illustrated in Fig. 2. Laser triangulation is a well-known technology, in which the surface measuring system 18 functions as laser triangulation digitizer using the laser source 19 to project a line or a single spot (projected as a line using mirrors) onto the surface 50, which reflects and is imaged by the camera 20. By having predetermined projection and collection angles relative to the baseline, the surface measuring system 18 can then determine a triangle’s dimensions and the coordinates of a point on the surface 50.

[0064] Through the above configuration, the surface measuring system 18 can detect the presence of the surface 50 while moving along the surface 50 upon a manipulation of the painting head 11 by means of the robot system 1.

[0065] As illustrated in Fig. 1, the robot system 1 further comprises a robot controller 90a. The robot controller 90a is configured to control the operation(s) of the robot system 1, including the operations of the robot arm arrangement 12, the operations of the painting head 11, the operations of the nozzle arrangement 14, and the operations of the surface measuring system 18, as described herein. The robot controller 90a is here an integral part of a control system 90, typically comprises processing circuitry 92. The robot controller 90a is configured to execute one or more control algorithms and motion instructions, thereby managing the robot's movements and operations. In Fig. 1, where the robot system 1 is an industrial robot system, the robot controller 90a is an integral part of a robot control system 90 configured to control the robot arm arrangement 12 and the painted head 11. Typically, although strictly not required, the control system 90 comprises one or more controllers 90a, 90b. In such configuration, a first controller 90a maybe arranged in the robot control system 90, and a second controller 90b maybe arranged in the painting head 11, wherein the second controller 90b maybe configured to control the operation of the painting head 11, including the nozzle arrangement 14 and the surface measuring system 18, based on instructions from the first controller 90a. The second controller 90b may thus be in communication with the first controller 90a. However, in other arrangements, the robot control system 90 may comprise a single controller, in which the processing circuitry 92 is configured to control the painting head 11, including the nozzle arrangement 14 and the surface measuring system 18, via one or more actuators. Hence, the painting head 11 and its components can be controlled in in several different manners by various actuators and controllers.

[0066] The control system 90, through the controllers 90a, 90b, of the robot system 1 is configured to manage the operations of the nozzle arrangement 14. Moreover, as mentioned above, the nozzle arrangement 14 is configured to deposit paint 30 onto the surface 50 of the vehicle 2. As such, in this example, the control system 90 is configured to control the nozzle arrangement 14 over the surface 50 to deposit the paint 30 onto the surface 50. Through the arrangement of the nozzle arrangement 14 in the painting head 11, the control system 90 can control the painting head 11 to deposit the paint 30 onto the surface 50 to form the painted surface region 22 on the surface 50.

[0067] In one example, the processing circuitry 92 is configured to perform painting of the surface 50 according to a painting sequence 21. The painting sequence 21 contains pre-determined robot paths and painting head paths for executing the painting of the surface 50. Data indicative of the painting sequence 21 is here stored in a memory, e.g. a memory 94 of the control system 90, or in a memory of the controller 90a. The painting sequence 21 generates one or more control signals and commands to the controllers and processing circuitry so as to paint the surface 50, and form the painted surface region 22 on the surface 50. While the painting sequence 21 is here typically generated in a common controller of the control system 90 configured to both generate the painting sequence 21 and control the robot system 1, as described herein, other options and combinations of generating the painting sequence 21 and controlling the robot system 1 by one or more controllers, one or more processing circuitries and one or more memories may likewise be conceivable.

[0068] The painting head 11 will now be further described with reference to FIG. 1 in conjunction with FIG. 2. FIG. 2 is a side view of the painting head 11 along the surface 50. As illustrated in FIG. 2, the painting head 11 comprises a leading part 15 and a trailing part 17. The leading part 15 refers to the portion at the front of the painting head 11, positioned forward relative to the direction of movement MD along the surface 50. The trailing part 17 refers to the portion at the rear of the painting head 11, positioned behind the leading part. The terms "leading" and "trailing" describe the spatial relationship of the parts of the painting head 11, where "leading" indicates the front portion and "trailing" indicates the rear portion.

[0069] In one example, as illustrated in FIGS. 1 and 2, the surface measuring system 18 is arranged in the leading part 15 of the painting head 11 and the nozzle arrangement 14 is arranged in the trailing part 17.

[0070] In addition, the laser source 19 is arranged before the camera 20 in the leading part 15. More specifically, the laser source 19 as arranged in a front region of the leading part 15 and the camera 20 is arranged in a rear region of the leading part 15.

[0071] Accordingly, as depicted in FIG. 2, the laser source 19 is arranged at the front of the painting head 11, followed by the camera 20, and then the nozzle arrangement 14, with each component positioned in the painting head 11 relative to the direction of movement MD of the painting head 11.

[0072] The operation of the painting head 11 along the surface 50 will now be described further with reference to FIG. 2 in conjunction with FIG. 3. In FIG. 3, the surface 50 to be painted is seen from the above. In this example, the painting on the surface 50 is performed by the controller 90b. As such, the controller 90b here comprises processing circuitry 92 configured to perform the following operations.

[0073] Firstly, the processing circuitry 92 is configured to control the surface measuring system 18 to detect a presence of the surface 50 within a predefined range 29. The predefined range 29 corresponds to an operational threshold for controlling paint deposition. More specifically, the predefined range represents an operational window within which the painting head 11 can detect the surface 50 and apply paint accurately. In this example, the predefined range 29 is a measure of an appropriate distance between the painting head 11 and the surface 50, as illustrated in FIG. 2. A value of the predefined range 29 can be stored in the memory 94 of the controller 90b. By way of example, the predefined range is a predetermined distance range of 0.5 to 15.0 mm. In another example, the predefined range is a predetermined distance range of 1.0 to 10 mm. In yet another example, the predefined range is a predetermined distance range of 2.0 to 7.0 mm.

[0074] As depicted in FIG. 2, during movement of the painting head 11 along the surface 50, the laser source 19 emits a laser beam 19 a onto the surface below the laser source 19. The reflected laser beam 19b is captured by the camera 20, which is positioned behind the laser source 19. The processing circuitry 92 uses laser triangulation to measure the distance between the painting head 11 and the surface 50. Such measurement allows the surface measuring system 18 to detect the presence of a paintable area 27 of the surface 50 within the predefined range 29, for example, between 2 mm and 7 mm.

[0075] As such, the processing circuitry 92 is configured to control the surface measuring system 18 to detect a presence of a surface within a predefined range. Typically, the processing circuitry 92 is configured to control the surface measuring system 18 to detect a presence of a surface within the predefined range 29 by moving the surface measuring system 18 over the surface 50 to detect a presence of a surface within the predefined range 29.

[0076] When the surface measuring system 18 detects a surface within the predefined range 29, indicating a paintable area 27, the processing circuitry 92 typically generates an image data matrix 27a indicative of the paintable areas 27 of the surface 50. One example of the image data matrix 27a is depicted in FIG. 3. As such, the processing circuitry 92 is configured to generate an image data matrix 27a indicative of one or more paintable areas 27 of the surface 50 based on the detected presence of the surface 50.

[0077] Responsive to the detected presence of the surface 50 and based on the generated image data matrix 27a, the processing circuitry 92 controls the nozzle arrangement 14 to deposit paint 30 on one or more regions 27b (see e.g. FIG. 2) of the surface 50 corresponding to one or more paintable areas 27 (see e.g. FIG. 3). Accordingly, the processing circuitry 92 is configured to control the nozzle arrangement 14 to deposit paint 30 on one or more regions 27b of the surface 50 corresponding to one or more paintable areas 27. More specifically, the nozzles 16 in the nozzle arrangement 14 are activated by the processing circuitry 92 to deposit paint 30 onto the corresponding region 27b of the surface 50, based on the real-time feedback provided by the surface measuring system 18. The real-time feedback here refers to the image data matrix 27a indicating the detected presence of the surface 50, i.e. the detected paintable areas 27 of the surface 50.

[0078] Typically, the processing circuitry 92 can identify both paintable areas and non-paintable areas of the surface 50 based on the data from the surface measuring system 18. Turning to FIG. 3, one example of a non-paintable area 26 is illustrated in the form of a hole, while the remaining areas of the surface 50 are here paintable areas 27. Accordingly, in cases where the surface measuring system 18 detects a region, or a part, of the surface 50 that is outside the predefined range 29, such as a hole or gap in the surface 50 (e.g., a sunroof opening on the vehicle 2), the robot system 1 identifies this as a non-printable area 26. In this context, it can also be noted that the absence of a reflection or a change in the detected surface geometry, such as an increased distance between the painting head 11 and the surface 50 also typically causes the robot system 1 to halt paint deposition by the nozzles 16. As the painting head 11 continues moving along the surface 50 and the surface measuring system 18 again detects that a region of the surface is within the predefined range 29, the nozzles 16 are reactivated, resuming paint deposition on the detected printable areas 27.

[0079] Accordingly, the movement and operation of the surface measuring system 18 along the surface 50 will provide measured geometric data, that provides a scanned profile of the surface profile, such as illustrated in FIG. 3. For each pixel or positional coordinate within the scanned profile, the robot system 1 evaluates whether the distance to the surface 50 falls within an acceptable range that indicates a paintable area 27. If the distance to the surface is within an acceptable threshold, the corresponding pixel is recorded as a "black" pixel in the output image, indicating a paintable area of the surface 50. Conversely, if the distance is outside the acceptable threshold, the corresponding pixel is recorded as a "white" pixel, indicating a non-paintable area of the surface 50. As the surface measuring system 18 precedes the array of nozzles 16 during the scanning and painting process, there exists an offset due to the spatial displacement between the surface measuring system 18 and the nozzles 16. Consequently, there is typically a time delay between the moment a region of the surface 50 is scanned by the surface measuring system 18 and the moment the nozzles 16 reach the corresponding position of the corresponding region of the surface 50 for painting. Typically, such delay is proportional to the speed at which the robot system 1 is operating. For example, the delay is proportional to the speed at which the painting head 11 moves over the surface 50.

[0080] Fig. 4 is a flowchart of exemplary steps of one example of a method 100 of controlling painting on the surface 50. In this example, the painting on the surface 50 is performed by the controller 90b. As such, the controller 90b here comprises processing circuitry 92 configured to perform the method 100 according to the examples. Accordingly, the method 100 is here a computer- implemented method. In other examples, the overall control system 90 of the robot system 1 is configured to implement the method 100 according to examples. The method 100 is intended for controlling painting of the surface 50 using the robot system 1 in FIGS. 1 to 3. The processing circuitry 92 is configured to perform the following steps.

[0081] The method comprises a step no of controlling the surface measuring system 18 to detect a presence of the surface 50 within the predefined range 29. The predefined range 29 here refers, or correspond, to corresponds to an operational threshold for controlling paint deposition. The predefined range 29 thus serves as a binary control for actuation of the nozzle arrangement 14, such that the nozzles 16 are activated to deposit paint 30 when the painting head 11 is within the predefined range 29 relative to the surface 50, and paint deposition is halted when the surface 50 is outside the predefined range 29. More specifically, the predefined range 29 is set as an operational threshold for the processing circuitry 92 to ensure optimal print quality. If the nozzles 16 exceed approximately 10 mm from the surface 50 (depending on the application), the paint quality may deteriorate. The predefined range 29 allows the system to determine whether the nozzles 16 are positioned correctly for painting, and dynamically adjust the paint deposition process.

[0082] Moreover, the method here comprises a step 120 of generating image data matrix 27a indicative of one or more paintable areas 27 of the surface 50 based on the detected presence of the surface 50.

[0083] Subsequently, the method comprises a step 130 of controlling the nozzle arrangement 14 to deposit paint 30 at the detected surface, responsive to the detected presence of the surface 50. In this example, the step 130 of controlling the nozzle arrangement 14 to deposit paint 30 at the detected surface means that the nozzle arrangement 14 is controlled to deposit paint 30 on one or more regions 27b of the surface 50 corresponding to one or more paintable areas 27. Accordingly, the method here comprises a step 130 of controlling the nozzle arrangement 14 to deposit paint 30 on one or more regions 27b of the surface 50 corresponding to one or more paintable areas 27, responsive to the detected presence of the surface 50 and based on the generated image data matrix 27a.

[0084] Such approach enables precise control of the painting process in real time, ensuring that paint 30 is applied only to surfaces within the correct range, while non-printable areas 26, such as holes or gaps, are automatically excluded from paint application.

[0085] The term "at the detected surface" as used herein should be understood to include paint deposition from nozzles that are positioned directly above, on, or in the vicinity of the surface, as determined by the surface measuring system. Typically, the step of controlling 130 the nozzle arrangement 14 to deposit paint 30 at the detected surface comprises controlling the nozzle arrangement 14 to deposit paint 30 only from those nozzles 16 that are positioned above the detected surface. For example, the term “above” may refer to a situation where the nozzles 16 are vertically above the detected surface. However, the term “above”, as used in this context, may also refer to another direction depending on the orientation of the painting head n and the surface 50 of the object 2.

[0086] By way of example, the step no of controlling the surface measuring system

[0087] 18 to detect a presence of a surface within the predefined range 29 comprises measuring surface geometry of the surface 50 and determining the surface profile based on the measured surface geometry. The measured surface geometry can be collectively referred to as surface geometry data or simple as surface data. In this example, the surface measuring system 18 is provided in the form of a 2D line scanner. The 2D line scanner comprises the laser source

[0088] 19 and the camera 20. Such type of surface measuring system 18 will sense the distance from the surface 50 to the camera 20 in a line (profile). The processing circuitry 92 uses this distance to determine if there is a paintable area 27 within the specified predefined range 29 from the camera 20. Such determination of the distance is possible as the 2D liner scanner, including the camera 20 and the laser source 19, and the nozzles 16 are fixed relative to each other, with a known position. The distance to the surface 50 can thus be calibrated against the 2D liner scanner, and then by extension also the nozzles 16. As the 2D liner scanner and the nozzle arrangement 14 are arranged with a fixed distance, it is thus also possible to determine that the surface is paintable by the nozzles 16. More specifically, the method 100 uses the 2D line scanner to measure the surface 50, and then identify the paintable areas 27 from the measured geometry data. The measured geometry data is transferred to the processing circuitry 92. Hereby, the control system 90, such as the controller 90b knows the actual location of each paintable area 27 on the surface 50. As the measured data contains data indicative of the actual surface 50, the measured data can also be considered as actual surface data. The measured data contains spatial data of the actual surface 50. The 2D line scanner can be controlled to scan the surface 50 to detect the paintable areas 27 from commands from the control system 90, such as from the controller 90a. The paintable areas 27 serve as references for the locations of regions to be painted by the nozzles 16 of the nozzle arrangement 14.

[0089] Typically, the surface measuring system 18 and the nozzle arrangement 14 are operatively coupled to perform surface detection and paint deposition in real time during a single operational pass. By operatively coupling the surface detection and paint deposition processes, the processing circuitry 92 is capable of painting a surface efficiently in a single operational pass. There is no need for advanced post-processing or generation of the complete image, improving the responsiveness and efficiency of the painting operation. In this context, the term “operatively coupled” refers to that the surface measuring system 18 and the nozzle arrangement 14 being functionally linked, allowing the surface measuring system 18 and the nozzle arrangement 14 to work together without delays or additional steps. Such configuration provides an immediate paint deposition based on surface detection. The relationship between these components ensures that the surface detection automatically triggers the corresponding paint action.

[0090] Single operational pass refers to completing both surface detection and paint deposition in one continuous movement. More specifically, a single operational pass refers to the entire process of surface detection and paint deposition being completed as the painting head 11 moves along the surface 50 just once. Such single operation pass is different to a method that might involve a first pass of scanning the surface entirely to gather data, a second pass of processing the data to generate an image or a map, and a second pass of using that processed data to finally deposit paint. To this end, a single operational pass allows for real-time painting as the robot system 1 detects the surface on-the-fly, making the entire process more efficient and responsive, without requiring multiple stages or complex image processing.

[0091] As such, in one example, the step 130 of controlling the nozzle arrangement 14 to deposit paint 30 is performed on-the-fly without generating a complete image of the surface 50 prior to initiating painting of the surface 50. Rather, the surface detection data is continuously processed in real time by the processing circuitry 92 as the surface measuring system 18 scans the surface 50. A complete image refers to a full, pre-generated representation of the entire surface to be painted before the painting process begins. That is, complete image generation means that a full dataset or model of the entire surface is created before the nozzles are activated. The painting process starts only when the entire surface geometry has been mapped and processed. As such, the term "without generating a complete image" means that the robot system 1 is using real-time feedback from the surface measuring system 18 to control paint deposition without waiting for the entire surface to be scanned or mapped before starting the painting process. Rather, the painting process starts while the surface is still being scanned and processed, and paint is applied dynamically based on detected presence of the surface, i.e. the detected paintable areas 27.

[0092] Typically, the detected surface data from the surface measuring system 18 is directly processed to control the corresponding paint deposition by the nozzle arrangement 14. In one example, the nozzle arrangement 14 is directly controlled based on the immediately available surface detection data without pausing or requiring the generation of a complete surface map or storing large amounts of surface data before paint deposition is initiated.

[0093] To this end, the actuation of the nozzle arrangement 14 is here based solely on measurement data provided by the surface measuring system 18.

[0094] The image data matrix 27a generated by the processing circuitry 92 can contain several different types of data. For example, the generated image data matrix 27a comprises a binary coverage map. The binary coverage map indicates paintable areas 27 of the surface 50 based on the detected presence of the surface 50 within the predefined range 29. In other words, the image data is binary, reflecting either paintable or non-paintable areas. By way of example, paintable areas are represented by black pixels and non-paintable areas by white pixels. As mentioned above, the predefined range 29 here operates as a binary control mechanism, where the nozzles 16 are either in the correct position to paint, or they are too far away, at which point the robot system 1 halts paint deposition. For example, when painting over a roof, the robot system 1 paints when the surface 50 is within range. However, if a sunroof appears, the distance increases, and the robot system 1 halts pain deposition as there is no paintable surface. When the roof resumes, and the surface 50 is detected within predefined range 29, paint deposition restarts automatically.

[0095] Thus, the processing circuitry 92 is here also configured to deposit paint 30 uniformly on the paintable areas 27 of the surface 59 represented by the binary coverage map. This means that the paint 30 is applied uniformly over the entire surface 50 deemed paintable, as indicated by the binary coverage map.

[0096] Referring again to FIG. 3, which illustrates further examples of painting the surface 50 using the robot system 1 in FIGS. 1 and 2. In FIG. 3, the surface 50 to be painted is seen from the above. As illustrated, the surface 50 further contains a hole, representing a non-paintable area 26. The painting head 11 comprises the surface measuring system 18 arranged at the leading part 15 and the nozzle arrangement 14 arranged at the trailing part 17 (of the painting head 11). The painting head 11 is moved along the moving direction MD and the surface measuring system 18 is controlled to detect a presence of the surface 50 within the predefined range 29. In this example, the surface measuring system 18 reads the surface 50 and will immediately process the scanned data. The surface measuring system 18 reads the surface 50 at a scanner line 18a. The distance between the scanner line 18a and the laser source 19 here defines the predefined range 29, corresponding to the distance between the painting head and the surface.

[0097] The surface data of the scanned surface is processed and transferred to a temporary buffer memory 94a as image data. Hence, in this example, the controller 90b comprises the memory 94 and an additional temporary buffer memory 94a, as also illustrated in FIG. 3. The temporary buffer memory 94a may be a separate memory or an integral part of the memory 94. In this example, the method 100 thus also comprises a step 112 of storing data indicative of the detected presence of the surface within the predefined range

[0098] 29 in the temporary buffer memory 94a. Temporary data storage allows for smooth operation even if there is a slight delay between detection and paint application, maintaining accuracy as the painting head moves.

[0099] As such, the step 120 of generating image data matrix 27a indicative of the paintable areas 27 of the surface 50 based on the detected presence of the surface comprises a step 122 of generating image data matrix 27a indicative of the paintable areas 27 of the surface 50 based on the stored data in the temporary buffer memory 94a, here containing detected presence of paintable area(s) 27 and detected presence of the non-paintable area(s) 26 of the surface 50. The data may for example be surface profile data. The surface profile data may contain the image data matrix 27a indicative of paintable areas 27 on the surface 50 and image data 26a indicative of non-paintable areas 26 on the surface 50. The surface profile data is arranged in rows of data with surface distance. As the surface distance between the surface measuring system 18 and the surface 50 is captured at a given robot arrangement position, the controller 90b is configured to create 3D data from the measured data from the surface measuring system 18, even if the scanned data is 2D.

[0100] Subsequently, responsive to the detected presence of the surface and based on the generated image data matrix, the controller 90b controls the nozzle arrangement 14 to deposit paint 30 at the detected surface, e.g. on the regions of the surface 50 corresponding to the paintable areas 27. More specifically, in this example, the step 130 of controlling the nozzle arrangement 14 to deposit paint 30 on regions of the surface 50 corresponding to the detected paintable areas 27 comprises a step 132 of controlling the nozzle arrangement 14 based on the data stored in the temporary buffer memory 94a as the painting head 11 moves over the surface 50. As illustrated in FIG. 3, the paint

[0101] 30 is deposited at a painting line 14a of the nozzle arrangement 14. Due to the movement of the painting head 11 in the moving direction MD, the location of the painting line 14a on the surface 50 corresponds to the previous location of the scanner line 18a (where the surface 50 was scanned by the laser source 19). Accordingly, the painting head 11 will paint the surface 50 based on the scanned data when the nozzle arrangement 14 reaches the corresponding point on the surface 50 from which the scanned data was obtained.

[0102] In an extended version of the method 100, the method 100 further comprises a step of receiving a digital image containing one or more graphics details. In this example, the nozzle arrangement 14 is further controlled based on the received digital image. The digital image is intended to be visualized (painted) on the surface 50 as an image. The digital image is defined by graphics details in the form of an array of pixels. The graphics details here refer to specific visual elements or design attributes of the digital image to be printed. For example, the graphics details define a decal. In one example, the graphics details provide a print design designed to produce a 3D visual effect on the surface 50. In one example, a customer of the vehicle 2 provides the digital image intended to be painted and visualized on the surface 50 in a digital file. The digital image with the graphic details are typically stored in the memory 94 of the control system 90, such as in the controller 90a.

[0103] It should be noted that the non-paintable areas may necessarily not be holes, but can also encompass other types of areas, such as the edges of the roof, sunroof borders, edges of a hood, door boundaries, and mounting holes for logos or emblems, and the like.

[0104] As mentioned herein, the surface measuring system 18 is positioned before the nozzle arrangement 14 in the painting head 11. In this manner, the surface measuring system 18 is positioned to detect the surface 50 immediately before the nozzle arrangement 14 deposits paint 30 on the surface 50. By way of example, the time from the acquisition of data by the surface measuring system 18 to the deposit of paint 30 by the nozzles 16 is determined by the predefined distance between the laser source 19 and the nozzle arrangement 14 and the velocity of the painting head 11 along the surface 50. The nozzles 16 should be arranged in the painting head 11 so that the nozzles 16 can deposit paint at the same position as where the data was captured.

[0105] The arrangement of the surface measuring system 18 before the nozzle arrangement 14 in the painting head 11 is particularly useful for allowing on- the-fly painting and painting in a single operational pass, as described above.

[0106] However, the surface measuring system 18 and the nozzle arrangement 14 can be arranged in several different manners in the painting head 11. In a first example, as illustrated in FIGS. 1 to 4, the laser sensor 19 of the surface measuring system 18 is arranged at the leading part 15 of the painting head 11 and the nozzle arrangement 14 is arranged at the trailing part 17 relative to the leading part 15. Moreover, the camera 20 of the surface measuring system 18 is arranged at the leading part 15 of the painting head 11 and the nozzle arrangement 14 is arranged at the trailing part 17 relative to the leading part 15. Also, the camera 20 is arranged in-between the laser source 19 and the nozzle arrangement 14.

[0107] In one example, the laser source 19 and the camera 20 of the surface measuring system 18 are combined into a single sensor unit arranged at the leading part 15 of the painting head 11.

[0108] However, it should be noted that location of the laser sensor 19 and the camera 20 can be varied relative to the position of the nozzle arrangement 14. In another example, the laser sensor 19 of the surface measuring system 18 is arranged at the leading part 15 of the painting head 11, while the camera 20 of the surface measuring system 18 is arranged at the trailing part 17 of the painting head 11. Moreover, the nozzle arrangement 14 is arranged inbetween the laser source 19 and the camera 20. The nozzle arrangement 14 can be arranged either at the leading part 15, although after the laser source 19, or at the trailing part 17, although before the camera 20. Accordingly, in one example, the surface measuring system 18 further comprises a camera 20 arranged at the trailing part 17 of the painting head 11, and wherein the nozzle arrangement 14 is positioned between the laser source 19 and the camera 20. Hence, in one example, the surface measuring system 18 comprises a laser source 19 arranged at the leading part 15 and a camera 20 arranged at the trailing part 17 of the painting head 11, and wherein the nozzle arrangement 14 is positioned centrally on the painting head 11.

[0109] It should be noted that although the examples above are described in relation to a surface 50 in the form of a roof surface of a vehicle 2, the surface may be another type of surface of the vehicle, including e.g. a hood surface, a side panel surface and the like. The top surfaces of a vehicle, including the roof and hood, are particularly suitable for painting because these surfaces are large, and relatively flat areas. Other types of surfaces maybe side panels, rear end and trunk lid. It should also be noted that the surface 50 may be a surface of any type of a 3D object. Other examples of vehicles besides passenger cars may be airplanes, underwater vessels and the like. In such examples, the surface 50 can be either the exterior surface or the interior of the vehicle.

[0110] Thanks to the present invention, as described herein in relation to the figures, there is provided an improved method of controlling painting of surfaces of complex 3D objects. The invention provides methods and systems configured to operate independently of any preloaded geometric data. By not requiring the comparison of scanned data to known geometry, the invention allows for more robust and adaptable painting of random or unknown objects, such as boxes or other irregular surfaces. This makes the method and system particularly useful for stand-alone applications where surface geometry may be unknown or irregular. For example, the painting head could be moved over a random object and still function effectively without prior knowledge of the surface. As the method and system rely less on pre-programmed geometry, the invention also offers a less complex solution for painting tasks. The absence of detailed geometric data or image processing allows the methods and systems to be quickly deployed in various environments, offering cost-effective and time-saving advantages, especially for smaller- scale or one-off projects. The above presentation of the robot system i should also be regarded as disclosing a control system 90 having one or more controllers 90a, 90b for controlling the robot system 1, for instance using the controller 90b and the processing circuitry 92. In addition, there is disclosed a controller 90b comprising processing circuitry 92 configured to control the surface measuring system 18 to detect a presence of the surface 50 within a predefined range 29, wherein the predefined range 29 corresponds to an operational threshold for controlling paint deposition; generate an image data matrix 27a indicative of one or more paintable areas 27 of the surface based on the detected presence of the surface; and responsive to the detected presence of the surface and based on the generated image data 27a, control the nozzle arrangement 14 to deposit paint 30 at the detected surface, such as depositing paint on one or more regions of the surface 50 corresponding to one or more paintable areas 27.

[0111] As described herein, the disclosure also relates to the control system 90, comprising controllers 90a, 90b, configured to execute the method 100 according to the above examples. The disclosure also relates a computer program comprising instructions to cause the controller 90 to execute the method of any of the above examples. It should be noted that the controller, as described herein, may include a microprocessor, microcontroller, programmable digital signal processor or another programmable processor device. The processing circuitry may also include a microprocessor, microcontroller, programmable digital signal processor or another programmable processor device, or instead, include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the processing circuitry includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

[0112] Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. Also, it should be noted that parts of the system and method may be omitted, interchanged or arranged in various ways, the system and method yet being able to perform the functionality of the present invention. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

33Claims1. A method (ioo) for painting a surface (50) of an object using a robot system (1), the robot system comprising a painting head (11), wherein the painting head comprises a nozzle arrangement (14) with a set of nozzles (16) for depositing paint (30) and a surface measuring system (18) configured to detect the surface, wherein the method comprises: controlling (no) the surface measuring system to detect a presence of the surface within a predefined range (29); and responsive to the detected presence of the surface, controlling (130) the nozzle arrangement to deposit paint at the detected surface.

2. The method according to claim 1, wherein controlling (no) the surface measuring system to detect a presence of a surface within a predefined range comprises measuring surface geometry of the surface and determining the surface profile based on the measured surface geometry.

3. The method according to any one of the preceding claims 1 to 2, wherein the surface measuring system and the nozzle arrangement are operatively coupled to perform surface detection and paint deposition in real time during a single operational pass.

4. The method according to any one of the preceding claims, wherein controlling (130) the nozzle arrangement to deposit paint at the detected surface comprises controlling the nozzle arrangement to deposit paint only from those nozzles that are positioned above the detected surface.

5. The method according to any one of the preceding claims, wherein controlling the nozzle arrangement to deposit paint is performed on-the-fly without generating a complete image of the surface prior to the initiation of painting of the surface.

346. The method according to any one of the preceding claims, further comprising storing data indicative of the detected presence of the surface within the predefined range in a temporary buffer memory (94a), and controlling the nozzle arrangement based on the data stored in the temporary buffer memory as the painting head moves over the surface.

7. The method according to any one of the preceding claims, wherein actuation of the nozzle arrangement is based solely on measurement data provided by the surface measuring system.

8. The method according to any one of the preceding claims, wherein the predefined range is a predetermined distance range of 0.5 to 15.0 mm, preferably the predefined range is a predetermined distance range of 1.0 to 10 mm, still preferably the predefined range is a predetermined distance range of 2.0 to 7.0 mm.

9. The method according to any one of the preceding claims, wherein the predefined range serves as a binary control for actuation of the nozzle arrangement, such that the nozzles are activated to deposit paint when the painting head is within the predefined range relative to the surface, and paint deposition is halted when the surface is outside the predefined range.

10. The method according to any one of the preceding claims, further comprising generating (120) an image data matrix indicative of one or more paintable areas of the surface based on the detected presence of the surface.

11. The method according to claim 10, wherein controlling (130) the nozzle arrangement to deposit paint at the detected surface comprises controlling, responsive to the detected presence of the surface and based on the generated image data matrix, the nozzle arrangement to deposit paint on one or more regions of the surface corresponding to one or more paintable areas.

12. The method according to claims 10 to 11, wherein the generated image data matrix comprises a binary coverage map, the binary coverage map indicating the paintable areas of the surface based on the detected presenceof the surface within the predefined range, and wherein paint is deposited uniformly on the paintable areas of the surface represented by the binary coverage map.

13. The method according to any one of the preceding claims, further comprising receiving a digital image containing one or more graphics details, and wherein the nozzle arrangement is further controlled based on the received digital image.

14. A controller (90, 90a, 90b) comprising processing circuitry (92) configured to execute the method of any one of claims 1 to 13.

15. A robot system (1) for painting a surface (50) of an object (2), the robot system comprising a robot arm arrangement (10) and a painting head (11) configured to be connected to the robot arm arrangement, wherein the painting head comprises a nozzle arrangement (14) with a set of nozzles (16) for depositing paint and a surface measuring system (18) configured to detect the surface, wherein the robot system further comprises one or more controllers (90, 90a, 90b) according to claim 14.

16. The robot system of claim 15, wherein a laser source of the surface measuring system is arranged at a leading part of the painting head and the nozzle arrangement of the painting head is arranged at a trailing part relative to the leading part.

17. The robot system of claim 15, wherein a camera of the surface measuring system is arranged at the leading part of the painting head, and the laser source being arranged before the camera in the leading part.

18. A computer program product comprising program code for performing, when executed by a controller, the method of any of claims 1 to 13.

19. A non-transitory computer-readable storage medium comprising instructions, which when executed by a controller, cause the controller to perform the method of any of claims 1 to 13.

Images