A robot system and a method

Abstract

The present invention relates to a robot system (1), comprising: a nozzle arrangement (14) configured to deposit an ultraviolet (UV) curable resin onto a surface (50); a robot arm arrangement (12) configured to move the nozzle arrangement over the surface; and a controller (90) configured to control the nozzle arrangement to deposit the UV curable resin onto the surface to form a drag-reducing pattern (20b).

Description

[0001] A ROBOT SYSTEM AND A METHOD

[0002] Technical Field

[0003] The present invention relates to robot systems and methods for controlling a robot system. In particular, the present invention relates to a controller for a robot system configured to control a nozzle arrangement to deposit a resin on a surface of an object, such as an external surface of a vehicle or the like.

[0004] Background

[0005] Drag reduction is a technical field in modern vehicle development that has seen increased interest due to its impact on vehicle efficiency and performance. Traditionally, the automotive industry has explored various methods to reduce aerodynamic drag, including streamlined designs and the incorporation of specific surface features. These methods, while effective to a degree, often face challenges related to manufacturing feasibility, cost, and aesthetic considerations.

[0006] Attempts to apply various drag reduction techniques have demonstrated potential but also revealed hurdles in practical implementation. These include difficulties in achieving precise, repeatable surface modifications and the complexity of integrating such features into the mass production process.

[0007] Despite the known benefits of surface pattern -based drag reduction, current technologies are limited in their ability to produce these features efficiently on the exterior surfaces of vehicles. Thus, there remains a need for an improved method that can reliably add drag-reducing surface features to exterior surfaces, such as surfaces on vehicles.

[0008] Summary In view of the above, it would be desirable to provide a robot system configured to assist in forming a drag-reducing pattern on a surface of a three-dimensional (3D) object, such as an exterior surface of a vehicle, thereby allowing for an improved method of forming drag-reducing patterns on surfaces. The object is at least partly achieved by a robot system 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 robot system, comprising: a nozzle arrangement configured to deposit an ultraviolet (UV) curable resin onto a surface; a robot arm arrangement configured to move the nozzle arrangement over the surface; and a controller configured to control the nozzle arrangement to deposit the UV curable resin onto the surface to form a drag-reducing pattern.

[0010] Hereby, there is provided an improved system and method for adding a dragreducing pattern on an exterior surface of a 3D-object using a UV curable resin, in which the drag -reducing pattern can be determined from data obtainable from e.g. a digital model of the object. The exterior surface maybe an exterior surface of a vehicle.

[0011] The invention is at least partly based on the insight that creating dragreducing patterns on exterior surfaces, particularly on vehicles, involves several challenges such as a lack of precision and repeatability. For example, traditional methods of creating drag-reducing patterns often lack the precision and repeatability needed for consistent aerodynamic performance. Manual processes or less precise automated systems can lead to variations that negatively affect the effectiveness of drag reduction.

[0012] By the proposed robot system, it becomes possible to form sustainable and effective drag-reducing patterns on surfaces in an automatic manner, while reducing material waste and operational costs. Moreover, the invention allows for a layer-by-layer application of UV curable resin, controlled by a precise robotic system. Each layer can be accurately deposited and cured, ensuring uniformity, and enhanced aerodynamic properties.

[0013] Typically, the controller may be configured to determine a drag -reducing pattern for the surface, and in response to the determined drag-reducing pattern, control the nozzle arrangement to deposit the UV curable resin onto the surface to form the determined drag-reducing pattern. By using a controller configured to determine a drag-reducing pattern for the surface and control the nozzle arrangement in response to the determined dragreducing pattern, it becomes possible to control the application of UV curable resin according to determined pattern, ensuring that the UV resin-based pattern is applied with high precision and consistency.

[0014] The controller may be configured to determine the drag-reducing pattern from data indicative of a suitable drag-reducing pattern for the surface. Hereby, it becomes possible to provide a tailor-made and accurate replication of the drag-reducing pattern for the surface, enhancing efficiency and performance consistency.

[0015] The nozzle arrangement may comprise one or more orifices configured to deposit the UV curable resin. A technical advantage may include providing a more precise control over the resin flow, further improving the accuracy of the pattern application.

[0016] According to examples, the drag-reducing pattern typically contain any one of a set of dimples, bumps, wavelets, and riblets. The nozzle arrangement may be controlled to deposit the UV curable resin onto the surface to form the drag-reducing pattern in response to a determined drag-reducing pattern containing any one of a set of dimples, bumps, wavelets, and riblets. Dimples, bumps, wavelets, and riblets are examples of drag-reducing patterns that can provide enhanced aerodynamic properties for various vehicle designs and conditions.

[0017] The nozzle arrangement may be an integral part of a painting head configured to be pivotably connected to a robot arm of the robot arm arrangement. Such an arrangement further improves flexibility and range of motion, enabling the system to reach more complex surface geometries.

[0018] Hence, the robot system may typically have a painting head comprising the nozzle arrangement.

[0019] The controller may be configured to control a UV light-emitting source to direct UV light towards the surface so as to cure the deposited UV curable resin. By way of example, the UV light-emitting source is an integral part of a painting head, further comprising the nozzle arrangement. Hence, in one example, the painting head may comprise UV light-emitting source configured to direct UV light towards the surface so as to cure the deposited UV curable resin. Such configuration of the painting head allows for a more immediate curing of the resin in comparison with a separate device for emitting UV lighting, thus reducing processing time and improving adhesion and durability of the patterns. The UV light-emitting source may in other examples be a separate system from the nozzle arrangement.

[0020] The controller may be configured to control the nozzle arrangement to deposit the UV curable resin onto the surface to form the drag-reducing pattern in a layer-by-layer arrangement. A layer-by-layer arrangement allows for improving the application of UV curable resin, as well as improving the structural integrity and effectiveness of the drag-fore reducing geometric patterns.

[0021] The painting head may further be configured to deposit paint onto the surface. Such configuration provides a more versatile system, allowing for the creation of both functional aerodynamic patterns and aesthetic paint finishes in a single process. By applying a layer of paint on top of the deposited UV curable resin, both the mechanical properties and the appearance may be increased. The painting head may comprise a painting nozzle arrangement configured to deposit paint. The painting nozzle arrangement may typically be a separate device than the nozzle arrangement. The painting nozzle arrangement and nozzle arrangement maybe integral parts of the painting head. Hence, the painting head may comprise a dual nozzle arrangement including the nozzle arrangement for the UV curable resin and the painting nozzle arrangement for the paint.

[0022] The controller may be configured to control the painting head to selectively deposit the UV curable resin and paint onto the surface to form a painted drag -reducing pattern in a layer-by-layer arrangement. A layer-by-layer arrangement of resin and paint further improves the surface treatment and the production efficiency.

[0023] The UV curable resin maybe applied without overspray. One technical advantage may be to improve material efficiency, reducing waste and environmental impact while lowering operational costs.

[0024] The robot system may be 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 system may reduce the complexity of the overall system architecture, while ensuring synchronized operation of the robot arm arrangement and nozzle arrangement.

[0025] According to a second aspect of the invention, there is provided a method of forming a drag-reducing pattern on a surface using a robot system, the robot system comprising a nozzle arrangement configured to deposit an ultraviolet (UV) curable resin onto the surface and a robot arm arrangement configured to move the nozzle arrangement over the surface, wherein the method comprises controlling the nozzle arrangement to deposit the UV curable resin onto the surface to form a drag-reducing pattern. 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.

[0026] The drag -reducing pattern may be determined from data indicative of a suitable drag-reducing pattern for the surface. The method may comprise determining a drag-reducing pattern for the surface, and, in response to the determined drag-reducing pattern, controlling the nozzle arrangement to deposit the UV curable resin onto the surface to form the drag-reducing pattern.

[0027] The provision of controlling the nozzle arrangement to deposit the UV curable resin onto the surface to form the drag-reducing pattern may comprise determining a first layer of the drag-reducing pattern containing the UV curable resin, and depositing UV curable resin onto the surface according to the determined first layer. Such operation of the method may improve the accuracy and consistency of pattern, ensuring the overall effectiveness of the drag-reducing pattern.

[0028] The method may further comprise applying UV light onto the deposited UV curable resin so as to cure the UV curable resin onto the surface.

[0029] The method may further comprise controlling the nozzle arrangement to deposit one or more additional layers of UV curable resin onto the surface according to a layer-by-layer arrangement. A layer-by-layer arrangement allows for improving the application of, improving the structural integrity and effectiveness of the drag-fore reducing geometric patterns.

[0030] The method may further comprise thoroughly curing the layer-by-layer arrangement of deposited UV curable resin using UV light. In this manner, the durability and effectiveness of the layer-by-layer drag-reducing pattern is improved. Typically, the step of curing the layer-by-layer arrangement of deposited UV curable resin is performed by a big scale UV light-emitting device that is different to the UV light-emitting source. However, in some examples, the step of curing the layer-by-layer arrangement of deposited UV curable resin is performed by the UV light-emitting source of the painting head.

[0031] The method may further comprise depositing paint onto the formed dragreducing pattern on the surface. Depositing paint onto the formed dragreducing pattern allows for enhancing the visual appeal of the surface while maintaining functional properties. For example, the method may further comprise controlling the painting head to deposit paint onto the formed dragreducing pattern on the surface. More specifically, the method may comprise controlling the painting nozzle arrangement to deposit paint onto the formed drag-reducing pattern on the surface.

[0032] There is also provided a controller configured to execute a method according to the second aspect, a computer program product comprising program code for performing, when executed by a controller, the method according to the second aspect, a controller for the robot system comprising processing circuitry configured to perform the method, and a non-transitory computer- readable storage medium comprising instructions, which when executed by the controller, cause the controller to perform the method according to the second aspect.

[0033] 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.

[0034] Brief Description of the Drawings

[0035] 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:

[0036] Fig. i schematically illustrates an example of a robot system according to the present invention;

[0037] Fig. 2 schematically illustrates an example of a painting head with a nozzle arrangement for a robot system according to the present invention;

[0038] Fig. 3 schematically illustrates an example of a sequence of the nozzle arrangement over a surface of a vehicle according to the present invention; Fig. 4 schematically illustrates an example of a drag -reducing pattern created by the nozzle arrangement; and

[0039] Figs. 5 and 6 are flow-charts of some examples of methods of creating a dragreducing pattern.

[0040] Detailed Description

[0041] In the present detailed description, various embodiments of robot systems 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. The same or similar reference numerals will be used to denote the same or similar structural features.

[0042] 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 i comprises at least one robot manipulator arrangement io. In some robot systems 1, the robot system 1 may comprise a plurality of robot manipulator arrangements io. The robot system i is here integrated into an automatic assembly line for vehicles 2, such as passenger cars. The robot system i is here also configured to perform a specific surface treatment on the vehicle 2, as will be further described herein with reference to figures i to 6. The vehicle 2 is one example of a three-dimensional (3D) object having an exterior surface. For ease of reference, the examples are described in relation to a 3D object in the form of the vehicle 2. In Fig. 1, the surface 50 is a hood surface of the vehicle 2.

[0043] With reference to Fig. 1, the robot manipulator arrangement 10 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 often designed to allow for easy integration into existing production lines. The base 40 maybe an integral part of the robot manipulator arrangement 10 or a separate part of the robot system 1. The robot manipulator arrangement io of Fig. 1 comprises a robot arm arrangement 12. For example, the robot arm arrangement 12 is rotatably arranged relative to 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 to the base 40. The joints enable a full 360-degree range of motion, allowing the robot arms 12a, 12b, 12c to rotate, pivot, and swing 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 it suitable for tasks that require high-quality finishes, such as automotive painting or aerospace finishing.

[0044] Moreover, as depicted in Fig. 1, the robot manipulator arrangement 10 comprises a painting head 11. In this example, the painting head 11 is configured to be pivotably connectable to the robot arm 12c. The painting head 11 is here connected to the robot arm arrangement 12 via a connection interface (not shown) disposed on the robot arm 12c. Hence, at least one of the robot arms comprises a connection interface 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. Hereby, the robot arm arrangement 12 is configured to move the painting head 11 over the various surfaces of the vehicle 2. Turning again to Fig. 1, the robot system 1 comprises a nozzle arrangement 14. As shown in Fig. 1, the painting head 11 comprises the nozzle arrangement 14. As such, the nozzle arrangement 14 is an integral part of the painting head 11, which is configured to be pivotably connected to the robot arm 12c. 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.

[0045] As illustrated in Fig. 1, the robot system 1 further comprises a controller 90. The controller 90 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 and the operations of the nozzle arrangement 14, as described herein. The controller 90 is here the control system of the robot system 1 and typically comprises processing circuitry 92. The controller 90 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 controller 90 is an integral part of a robot control system configured to control the robot arm arrangement 12 and the nozzle arrangement 14. Typically, although strictly not required, the controller 90 may comprise one or more subcontrollers 90a, 90b. In such configuration, a first sub-controller 90a is arranged in the robot control system, and a second sub-controller 90b is arranged in the painting head 11, and configured to control the operation of the painting head 11 and / or the nozzle arrangement 14 based on instructions from the first sub-controller 90a. The second sub-controller 90b is thus in communication with the first sub-controller 90a. However, in other arrangements, the robot control system comprises a single controller 90, in which the processing circuitry 92 is configured to control the nozzle arrangement 14 and / or the painting head 11 directly via one or more actuators. For example, the painting head 11 can be controlled by one or more piezoelectric actuators (not shown), as is commonly known in the art.

[0046] The controller 90 of the robot system 1 is configured to manage the operations of the nozzle arrangement 14. Moreover, the nozzle arrangement 14 is configured to deposit an ultraviolet (UV) curable resin 32 onto at least one surface 50 of the vehicle 2. As such, in this example, the controller 90 is configured to control the nozzle arrangement 14 over the surface 50 to deposit the UV curable resin 32 onto the surface 50. More specifically, the controller 90 is configured to deposit UV curable resin 32 over the surface 50 so as to create a drag -reducing pattern 20. In this context, the term dragreducing pattern typically refers to a geometric pattern adapted to help in reducing the resistance a body (3D object) faces when moving through a fluid (like air or water). The drag -reducing pattern is thus a drag-force reducing geometric pattern. The drag-reducing pattern is designed with geometric considerations to influence the forces acting on the body, such as a 3D object in the form of a vehicle.

[0047] In order to form a drag-reducing pattern 20 that is suitable for the surface 50 of the vehicle 2, the controller 90 initially determines the characteristics of the drag-reducing pattern 20 based on the type of surface and type of 3D object, such as type of vehicle.

[0048] As such, the controller 90 is configured to determine a drag -reducing pattern 20 for the surface 50 in advance of the deposition of the UV curable resin 32 onto the surface 50. For ease of reference, the determined drag-reducing pattern for the surface 50 is here indicated by reference numeral 20a. The determined drag-reducing pattern 20a is stored in a memory 94 of the controller 90. Byway of example, the controller 90 is configured to determine the drag-reducing pattern 20, 20a from data indicative of a suitable drag-reducing pattern for the surface 50.

[0049] In one example, the drag-reducing pattern 20a for the surface 50 is derived from a digital model containing the design and placement of drag-reducing patterns on the surface 50. The digital model is e.g. created by a digital model creation unit configured to generate the digital model. The controller 90 is here configured to use a CAD software to generate the digital model. Moreover, a suitable drag-reducing pattern 20a can be obtained by means of an aerodynamic analysis tool configured to determine a suitable drag- reducing pattern with distinct geometrical characteristics based on the identified geometry of the surface and data indicative of the field of use for the vehicle. The identified geometry of the surface 50 is performed using 3D scanning, which is a commonly used technology. The 3D scanning is performed by a 3D scanner. Typically, the drag-reducing pattern 20 is adjusted (fitted) based on the performed 3D scan of the surface 50, to which the digital model, such as a 3D CAD model, needs to be adapted. The adjusted drag-reducing pattern then constitutes a predetermined dragreducing pattern 20, 20a. The predetermined drag-reducing pattern 20a is stored in the memory 94 of the controller 90.

[0050] Subsequently, in response to the determined drag-reducing pattern 20, 20a, the controller 90 is configured to control the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the determined drag -reducing pattern 20. For ease of reference, the formed drag-reducing pattern on the surface 50 is here indicated by reference numeral 20b. The UV curable resin 32 is supplied by depositing droplets of the UV curable resin 32 on the surface 50.

[0051] In the context of the invention, the UV curable resin is a resin that cures (solidifies or hardens) upon exposure to UV light. Hence, the term UV curable resin refers to a UV-light curable resin. In this context, the term “curing” refers to the process of the resin becoming rigid by forming a network of chemical bonds in response to UV exposure. This may also refer to photopolymerization, where UV light enables creation of polymers (long chains of atoms). The outcome of the curing process is that the resin becomes hardened.

[0052] While there are several different types of resins, the UV curable resin 32 should preferably have the appropriate viscosity and rheological properties for being suitable for deposition by the nozzle arrangement 14 in an automated process performed by the robot system 1. It should be noted that a suitable UV curable resin 32 is typically selected in view of the type of surface and field of use of the object, as well as the type of nozzle arrangement. In addition, or alternatively, an initial test of the selected UV curable resin 32 is conducted on a minor area of the surface, or on part of a material corresponding to the surface. Typically, the UV curable resin 32 should be in a range of viscosity that matches the operation of the painting head and the nozzle arrangement it uses. The UV curable resin 32 should typically also be enough viscous to maintain its shape once deposited. It should also be quick enough to harden to hold a second layer of resin after only short UV light exposure, but not so quickly that it clogs the nozzle or hardens before proper placement. Examples of suitable UV curable resins 32 are acrylate-based resins or thiol-ene resins. Such types of resins may also be used in conjunction with inks and / or other coloring agents. Hence, other examples of UV curable resins 32 may be UV-curable inks containing resinous materials that polymerize and harden when exposed to UV light. Therefore, also some types of inks that comprise a UV curable resin may be conceivable, such as an ink formulation comprising any one of an acrylate-based UV resin and thiolene UV resin.

[0053] Turning to Fig. 2, there is depicted one example of the painting head 11 comprising the nozzle arrangement 14 for use in the robot system 1 of Fig. 1. As illustrated in Fig. 2, the nozzle arrangement 14 comprises one or more orifices 15 configured to deposit the UV curable resin 32. The UV curable resin 32 is supplied to the nozzle arrangement 14 via a first fluid conduit, which herein is denoted as a resin fluid conduit 33. The resin fluid conduit 33 of Fig. 2 is an integral part of the nozzle arrangement 14, and thus an integral part of the painting head 11. The resin fluid conduit 33 is fluidly connected to a resin reservoir (not shown), that can be arranged on the robot system 1 or external of the robot system 1.

[0054] In Fig. 2, the painting head 11 is further configured to deposit paint 30. The paint is e.g. a colorant. One type of colorant is ink. The paint 30 is supplied to the painting head 11 via a second fluid conduit, which herein is denoted as a paint fluid conduit 31. The paint fluid conduit 31 of Fig. 2 is an integral part of the painting head 11. The paint fluid conduit 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 i or external of the robot system i. It should be noted that the term “colorant” typically encompasses any substance used to impart color, including inks, dyes, pigments, and other material.

[0055] As shown in Fig. 2, the painting head n here comprises a painting nozzle arrangement 19 configured to deposit the paint 30. The painting nozzle arrangement 19 is arranged in the painting head 11 separate from the nozzle arrangement 14, and is thus a separate device of the painting head 11. However, the painting nozzle arrangement 19 and the nozzle arrangement 14 are integral parts of the painting head 11. Hence, the painting head 11 comprises a dual nozzle arrangement including the nozzle arrangement 14 for the UV curable resin 32 and the painting nozzle arrangement 19 for the paint 30. The painting nozzle arrangement 19 is fluidly connected to the paint fluid conduit 31, as shown in Fig. 2.

[0056] As such, the painting head 11 is here a painting head configured to deposit both paint 30 and UV curable resin 32 on the surface 50. One example of such painting head 11 is an ink-jet painting head. As such, the nozzle arrangement 14 is configured to deposit ink 30 and UV curable resin 32.

[0057] Through the arrangement of the painting nozzle arrangement 19 and the nozzle arrangement 14 in a common painting head 11, the controller 11 can control the painting head 11 to selectively deposit the UV curable resin 32 and paint 30 onto the surface 50 to form a painted drag-reducing pattern in a layer-by-layer arrangement.

[0058] In addition, in Fig. 2, the painting head 11 further comprises a UV-light emitting source 16. The UV-light emitting source 16 is configured to direct UV light 16a towards the surface 50 so as to cure the deposited UV curable resin 32. The UV-light emitting source may be a UV lamp, a UV LED or the like.

[0059] As such, in Fig. 2, the painting head 11 is configured to deposit UV curable resin 32, deposit paint 30, such as ink, and further configured to cure the UV curable resin 32 by emitting UV light. The UV curable resin 32 is thus cured to form a harden resin layer on top of the surface 50.

[0060] In some examples, when the painting head 11 comprises the UV-light emitting source 16, the painting head 11 is controllable by the controller 90 to direct UV light towards the surface 50 so as to cure the deposited UV curable resin 32 to a first hardening level, while another curing unit (not shown) of the robot system 1 is controlled by the controller to cure the UV curable resin 32 to a second hardening level. As such, the robot system 1 may further comprise an additional UV curable resin curing unit configured to cure the UV curable resin 32 to a second level. The additional UV curable resin curing unit may for example be a big scale UV light-emitting device.

[0061] The painting head 11 and the nozzle arrangement 14 can be controlled in several different manners by the controller 90. Byway of example, the nozzle arrangement 14 is controlled to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern 20 in response to a determined drag-reducing pattern 20a containing any one of a set of dimples, bumps, wavelets, or riblets. For example, the formed drag-reducing pattern 20b comprises a set of bumps 25. Fig. 4 shows one example of a drag-reducing pattern 20b comprising a set of first bumps 25a and a set of second bumps 25b, wherein the geometry of the set first bumps 25a is different to the geometry of the set of second bumps 25b.

[0062] In addition, or alternatively, the controller 90 is configured to control the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern 20b in a layer-by-layer arrangement.

[0063] With reference to Figs. 3 and 4, one example of creating a drag-reducing pattern 20 to the surface 50 of the vehicle 2 is described hereinafter. As illustrated in Fig. 4, the formed drag-reducing pattern 20b includes two distinct types of bumps with different geometries, denoted as the first bumps 25a and the second bumps 25b. Optionally, the robot system 1 may clean the surface 50 thoroughly to remove all contaminants and debris. The controller 90 then receives data containing the suitable drag -reducing pattern 20 of the surface 50. The suitable drag-reducing pattern 20 is here obtained by means of an aerodynamic analysis tool configured to design a drag-reducing pattern that includes e.g. two sets of bumps: the first bumps 25a and the second bumps 25b, each with distinct geometrical characteristics. As such, the controller 90 determines that the derivable suitable drag-reducing pattern 20 is the determined drag-reducing pattern 20a for the surface 50 of the vehicle 2. The controller 90 is then configured to direct the nozzle arrangement 14 to apply these bumps 25a, 25b in a specified arrangement and sequence according to the determined drag-reducing pattern 20a. Hence, the controller 90 may also be configured to receive data indicative of the path for the nozzle arrangement 14 so as to form the determined drag-reducing pattern 20a on the surface 50. The controller 90 initiates the robot arm arrangement 12 to start the movement of the nozzle arrangement 14 over surface 50. Then, the controller 90 controls the nozzle arrangement 14 to deposit a first layer of UV curable resin 32 to form the first set of bumps 25a. Each bump is applied with the specific geometry, as determined in advance by the controller 90. The controller 90 continues with a subsequent layer of UV curable resin 32 to form the second set of bumps 25b, ensuring the geometry differs from the first set as planned. Subsequently, the controller 90 controls the nozzle arrangement 14 so that the freshly applied UV curable resin 32 is exposed to the UV light to cure and solidify the bumps 25, 25a, 25b. The controller 90 typically controls the nozzle arrangement 14 so that the light from the UV light source 16 evenly covers the entire drag-reducing pattern 20b to achieve consistent curing.

[0064] The created drag-reducing pattern 20b is hereby applied to the surface 50 so as to enhance aerodynamic performance during operation of the vehicle 2.

[0065] In addition, as mentioned above, the painting head 11 is here further configured to deposit paint 30 onto the surface 50, such as a colorant in the form of ink. As such, the painting head 11 is configured to deposit ink. In an extended example, the controller 90 is configured to control the painting head 11 to selectively deposit the UV curable resin 32 and paint 30 onto the surface 50 to form a painted drag-reducing pattern in a layer-by-layer arrangement.

[0066] It should also be noted that in some examples, the UV curable resin 32 is applied without overspray. As such, the deposition of UV curable resin 32 works similar to an inkjet printer, which is also overspray free.

[0067] It should be noted that although the examples above are described in relation to a surface in the form of a hood surface of a vehicle, the surface maybe another type of surface of the vehicle, including e.g. a roof surface, a side panel surface and the like. The top surfaces of a vehicle, including the roof and hood, are particularly suitable for drag-reducing patterns because these surfaces are large, and relatively flat areas where air flow can be easily managed to reduce air resistance. Other types of surfaces may be side panels, rear end, trunk lid and front bumper (and / or grill area). It should also be noted that the surface 50 may be a surface of any type of three-dimensional (3D) object. The surface 50 is typically an exterior surface of the 3D object. The exterior surface is typically the outermost surface that is exposed to the external environment. Other examples of vehicles besides passenger cars may be airplanes, underwater vessels and the like. In such examples, the surface 50 is the exterior surface of the vehicle.

[0068] Moreover, it should be noted that although the nozzle arrangement 14 is typically an integral part of the painting head 11, the nozzle arrangement 14 may in other examples be directly connectable to the robot arm arrangement 12. Hence, it may suffice that the robot system 1 comprises a robot arm arrangement 12, which is configured to move the nozzle arrangement 14 over the surface 50.

[0069] It should be noted that the above presentation of the robot system 1 should also be regarded as disclosing a method for controlling the robot system 1, for instance using the controller 90 and the processing circuitry 92. More specifically, there is provided a method 100 of forming a drag-reducing pattern 20 on the surface 50 using the robot system 1. The controller 90 is configured to perform the method 100 of Figs. 5 and 6. Thus, the method 100 is here a computer-implemented method.

[0070] Fig. 5 is a flowchart of an example of a method 100 of forming a dragreducing pattern 20 on the surface 50 using the robot system 1. The robot system 1 comprises the nozzle arrangement 14 configured to deposit the UV curable resin 32 onto the surface 50 and the robot arm arrangement 12 configured to move the nozzle arrangement 14 over the surface 50. The processing circuitry 92 is configured to perform the following steps.

[0071] Initially, the method 100 comprises an optional step no of determining a drag-reducing pattern 20, 20a for the surface 50. Moreover, the method 100 comprises a step 120 of controlling the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern 20, 20b in response to the determined drag-reducing pattern 20, 20a.

[0072] Byway of example, the drag -reducing pattern 20 is determined from data indicative of a suitable drag-reducing pattern 20a for the surface 50.

[0073] The step 120 of controlling the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern 20 can be performed in several different manner. For example, the step 120 of controlling the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern 20 comprises determining a first layer of the drag-reducing pattern 20 containing the UV curable resin 32, and depositing UV curable resin 32 on the surface 50 according to the determined first layer.

[0074] Optionally, the method 100 further comprises a step 130 of applying UV light onto the deposited UV curable resin 32 so as to cure the UV curable resin 32 deposited on the surface 50. The step 130 of applying UV light onto the deposited UV curable resin 32 is typically performed subsequent the step 120. However, the step 130 of applying UV light onto the deposited UV curable resin 32 may also be performed concurrent with the step 120. Through the operations of the method using the nozzle arrangement 14 to deposit UV curable resin 32 onto the surface 50, and not cure the UV curable resin 32 until it is deposited on the surface 50, it becomes possible to avoid that the conduit and orifices of the nozzle arrangement become clogged with harden resin.

[0075] Typically, the method 100 comprises controlling the nozzle arrangement 14 to deposit one or more additional layers of UV curable resin 32 onto the first layer of UV cured resin on the surface 50 according to a layer-by-layer arrangement. For example, the controller 90 is configured to deposit the UV curable resin 32 on the surface 50 in a layer-by-layer arrangement in an iterative manner. Typically, the UV curable resin 32 is deposited in a layer- by-layer arrangement on the surface 50 in an iterated manner until the determined drag-reducing pattern 20b is formed on the surface 50. To this end, the controller 90 controls the nozzle arrangement 14 to deposit UV curable resin 32 onto the surface 50 in a layer-by-layer arrangement until the drag-reducing pattern 20b on the surface 50 matches the determined dragreducing pattern 20a, which is typically stored in the memory 94 of the controller 90.

[0076] In the example where the nozzle arrangement 14 is controlled to deposit UV curable resin 32 onto the surface 50 according to a layer-by-layer arrangement, the method 100 typically further comprises a step of applying UV light onto the deposited UV curable resin 32 in-between each layer of deposited UV curable resin 32.

[0077] Finally, the method 100 here comprises a step of thoroughly curing the layer- by-layer arrangement of deposited UV curable resin 32 by the big scale UV- light emitting source. In this manner, the method may comprise an intermediate step of curing the UV curable resin 32 between the layers just enough to make it possible to build next layer, while the entire layer-by-layer arrangement is ultimately thoroughly cured by the big scale UV-light emitting source. It should be noted that the step of curing the layer-by-layer arrangement of deposited UV curable resin is here performed by a big scale UV light-emitting device that is different to the UV light-emitting source 16. However, in some examples, the step of curing the layer-by-layer arrangement of deposited UV curable resin is performed by the UV lightemitting source 16 of the painting head n.

[0078] It should be noted that in one example, the method 100 may be performed based on step 120, only. For example, in example, the method 100 comprises controlling 120 the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern. Analogously, the invention also relates to a controller 90 configured to control the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form a drag-reducing pattern 20b. As such, in example, there is provided a robot system 1 comprising the nozzle arrangement 14 configured to deposit an ultraviolet (UV) curable resin 32 onto the surface (50), the robot arm arrangement 12 configured to move the nozzle arrangement 14 over the surface 50, and the controller 90 configured to control the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form a determined drag-reducing pattern 20b. Accordingly, the controller and method may necessarily not include the operation of determining the drag-reducing pattern 20b.

[0079] Fig. 6 shows another example of a method 100 of forming a drag-reducing pattern 20 on the surface 50 using the robot system 1. The method 100 in Fig. 6 typically comprises the steps of the method 100 in Fig. 5, as described above. At least, the method 100 of Fig. 6 comprises the step no of determining a drag-reducing pattern 20, 20a for the surface 50, and, in response to the determined drag-reducing pattern 20, 20a, the step 120 of controlling the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50 to form the drag-reducing pattern 20, 20b.

[0080] In Fig. 6, the method 100 also comprises the step 130 of applying UV light onto the deposited UV curable resin 32 so as to cure the UV curable resin 32 deposited on the surface 50. Moreover, in Fig. 6, the method 100 further comprises a step 140 depositing paint 30 over the formed drag-reducing pattern 20b on the surface 50. In this example, the paint 30 is ink. Ink is one example of a paint that is useful for surfaces of vehicles, and which may have a positive impact on the adhesion of the UV curable resin 32. The paint 30 is typically applied as a layer over the deposited UV curable resin 32. By applying a layer of paint 30 on top of the deposited UV curable resin 32, both the mechanical properties and the appearance may be increased. By way of example, the painting head 11 is controlled to deposit the paint 30 over the formed drag-reducing pattern 20b.

[0081] Typically, when the painting is completed, the method 100 here comprises a step of thoroughly curing the deposited UV curable resin 32 and the paint 30 by the big scale UV-light emitting source.

[0082] In some examples, although not illustrated, the robot system 1 may also be controlled to apply a corrosion protection coating on the surface 50. The corrosion protection coating can be applied before, concurrent, and / or subsequent the deposition of the UV curable resin 32 and the paint 30. Moreover, the corrosion protection coating can be applied by the paint head 11, the nozzle arrangement 14, and / or by a separate nozzle configured to apply corrosion protection coating on a surface of an object, as is commonly known in the art.

[0083] In some examples, although not illustrated, the robot system 1 may also be controlled to apply a clear coat on top of the paint 30 and the deposited UV curable resin 32. The clear coat provides additional mechanical protection.

[0084] In addition, the method 100 may further comprise controlling the nozzle arrangement 14 to compensate for any geometric change of the surface 50 after the applied layer of paint and the applied clear coat. Such configuration of the method maybe useful as real parts often exhibit variations in comparison with the digital model of the real parts due to manufacturing tolerances, material properties, and environmental conditions. In practical applications, especially when dealing with curved surfaces like those found on vehicles, these variations can lead to differences in the actual surface geometry compared to the digital model (such as the CAD model). For instance, if dimples or specific patterns need to be applied to a surface with a given curvature, the actual curvature will inevitably vary between different parts. Some parts may exhibit greater curvature while others may be less pronounced. Traditional 3D printing techniques typically assume flat, ideal surfaces, which do not account for such real-world discrepancies. Consequently, the printed features may not align correctly with the intended design when applied to non-perfect surfaces. This issue is particularly pronounced in automotive applications where the surfaces are rarely perfectly flat or uniformly curved. To this end, by controlling the nozzle arrangement 14 to compensate for the geometric change of the surface 50 after the applied layer of paint and the applied clear, the drag-reducing pattern 20, such as dimples, can be even more accurately placed according to the actual surface geometry of the surface, leading to higher accuracy and consistency in the final drag -reducing pattern 20. Merely as an example, assuming a scenario where a vehicle door panel needs to be equipped with a series of dimples for functional purposes. The CAD model specifies the precise locations for these dimples based on a perfect surface curvature. However, due to manufacturing variances, one door panel may have a slightly steeper curve in certain areas compared to another. By using the configuration, the nozzle arrangement 14 can detect these variances in realtime and adjust the nozzle arrangement path accordingly. As a result, the dimples are placed in the correct positions relative to the actual surface, providing a more uniform appearance and performance across all parts.

[0085] Typically, although strictly not required, the method may comprise an initial step of scanning the surface 50 of the 3D object 2, such as the surface of the vehicle, prior to controlling the nozzle arrangement 14 to deposit the UV curable resin 32 onto the surface 50. A 3D scan of the vehicle 2 is typically performed so as to identify and compensate for any inaccuracies in the geometry of the surface 50. Such ccompensation typically involves bending, moving, and otherwise transforming the perfect 3D model to match the theoretical base surface to the real base surface. Subsequently, the digital model may be updated based on the identified inaccuracies and any determined compensation, and stored in the memory 90 for use of the controller 90 when forming the drag-reducing pattern 20.

[0086] Thanks to the present invention, as described herein in relation to the figures, there is provided a robot system 1 and a method 100 for depositing UV curable resin onto a surface of a 3D object, such as a surface of a vehicle, in order to create a drag-reducing pattern on the surface. The UV curable resin is deposited onto the surface using a nozzle arrangement and based on a predetermined drag-reducing pattern, allowing for providing a more tailor- made aerodynamic pattern on the surface in an automatic manner.

[0087] As described herein, the disclosure also relates to the controller 90, which is configured to execute the method 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 90, as described herein, may include a microprocessor, microcontroller, programmable digital signal processor or another programmable processor device. The processing circuitry 92 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 92 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.

[0088] 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 maybe omitted, interchanged or arranged in various ways, the system and method yet being able to perform the functionality of the present invention.

[0089] 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

Claims1. A robot system (1), comprising: a nozzle arrangement (14) configured to deposit an ultraviolet (UV) curable resin (32) onto a surface (50); a robot arm arrangement (12) configured to move the nozzle arrangement over the surface; and a controller (90) configured to control the nozzle arrangement to deposit the UV curable resin onto the surface to form a drag-reducing pattern (20b).

2. The robot system of claim 1, wherein the controller is configured to determine the drag-reducing pattern from data indicative of a suitable dragreducing pattern (20a) for the surface.

3. The robot system according to any one of the preceding claims, wherein the controller is configured to control a UV light-emitting source (16) to direct UV light towards the surface so as to cure the deposited UV curable resin.

4. The robot system according to any preceding claims, wherein the controller is configured to control the nozzle arrangement to deposit the UV curable resin onto the surface to form the drag-reducing pattern in a layer- by-layer arrangement.

5. The robot system according to any one of the preceding claims, wherein the nozzle arrangement is an integral part of a painting head (11) configured to be pivotably connected to a robot arm of the robot arm arrangement.

6. The robot system of claim 5, wherein the painting head is further configured to deposit paint onto the surface.

7. The robot system of claim 6, wherein the controller is configured to control the painting head to selectively deposit the UV curable resin and paint onto the surface to form a painted drag-reducing pattern in a layer-by- layer arrangement.

8. A method (ioo) of forming a drag-reducing pattern on a surface (50), using a robot system (1), the robot system comprising a nozzle arrangement (14) configured to deposit an ultraviolet (UV) curable resin onto the surface and a robot arm arrangement (12) configured to move the nozzle arrangement over the surface, wherein the method comprises:- controlling (120) the nozzle arrangement to deposit the UV curable resin onto the surface to form a drag-reducing pattern.

9. The method of claim 8, wherein the drag-reducing pattern is determined from data indicative of a suitable drag-reducing pattern for the surface.

10. The method according to any preceding claims 8 to 9, wherein controlling (120) the nozzle arrangement to deposit the UV curable resin onto the surface to form the drag-reducing pattern comprises determining a first layer of the drag-reducing pattern containing the UV curable resin, and depositing UV curable resin on the surface according to the determined first layer.

11. The method according to any preceding claims, further comprising applying (130) UV light onto the deposited resin so as to cure the UV curable resin onto the surface.

12. The method of claim 11, when dependent on claim 10, further comprising controlling the nozzle arrangement to deposit additional one or more layers of UV curable resin onto the surface according to a layer-by-layer arrangement.13- The method according to any preceding claims, further comprising depositing (140) paint over the formed drag-reducing pattern.

14. A controller (90) configured to execute the method of any of claims 8 to13.

15. A computer program product comprising program code for performing, when executed by a controller, the method of any of claims 8 to 13.

16. 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 8 to 13.

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