TECHNICAL FIELD

The present invention relates to the field of tracking, capturing and observing sports-related actions and events based on computer vision and machine learning. In particular, the invention relates to an apparatus, a method and a computer program for using relatively small and simple cameras at a relatively low cost, for determining the position of the court / table, player, racket as well as positioning the ball with high accuracy. Above all, the intended application for the equipment is in various racquet sports (such as tennis, table tennis, badminton, padel and squash).

BACKGROUND

There are currently only a few vendors on the market that provide various computer vision and tracking systems with particular application in racquet sports. Especially for tennis, which despite fierce competition from several other racquet sports, can probably be considered the largest and geographically most evenly distributed of the racquet sports, there are some prior art tracking and computer vision systems that all work in different ways and with their respective strengths and weaknesses. A common denominator for these well-known systems with brands such as Hawk-Eye, Playsight and Foxtenn is that they require a number of cameras, which are either to be mounted high and directed downward, or are to be mounted low and directed obliquely upward, for example placed under the net and with transparent glass sections levelled with the floor / ground level. Common to the various camera mounts is that they all have and require advanced and high-resolution precision optics. Also in other respects, these systems are relatively complicated and expensive to install, maintain and use. At present, it is thus mostly larger and resourceful international tournaments with professional tennis players that can afford and have the opportunity to use such systems, and without generous sponsors, this assistance for players, referees, spectators and TV viewers would no longer be possible.

There are also a number of other systems, which are considerably less costly than the previously mentioned, and which do not need to be mounted high above the floor on, for example, a tennis court, but can be placed at a more suitable and practical height, such as on about one meter's height above the floor level. These systems are known by brands such as Baseline Vision, Wingfield and Zennis. The latter system, however, differs somewhat from the previous ones by having sensors mounted at a certain height above the track. However, these systems, as well as the more complex and costly systems, are all associated with various problems and weaknesses. As an example of the above can be mentioned that the optical equipment and required components are too space-consuming or need to be mounted in such a way that during normal operation they interfere with the game or do not meet applicable requirements and regulations within the respective racket sports in order to function satisfactorily.

With particular reference to the above drawbacks of prior art systems, an example can be found in the published international patent application WO 2019/244153 Al. This application describes a device, system and method for computer vision, object tracking and image analysis, in particular intended for analysis of images or video sequences of tennis. The system includes two adjacent and co-located cameras, oriented at an angle of 20° - 120° to each other, which have a combined field of view that covers most of a tennis court. A processor analyses information obtained from the cameras using computer vision algorithms.

There are a few more systems, which, however, show a precision that is too deficient to be acceptable and work in practice. These systems are simply not advanced enough to be able to collect qualitative information with which one can, with satisfactory probability, assess whether a ball is to be judged as right or wrong (in or out), i.e. bounce on or off a certain line, or even be able to collect statistical information about a player's specific game patterns or actions.

No previously known system has succeeded in solving the problem of providing a technical solution that is robust and functional, and offers satisfactory precision and reliability, to conditions attractive to the mass market, and which at the same time can be easily, smoothly and safely mounted in a manner consistent with current regulations for the various racquet sports.

SUMMARY OF THE INVENTION

The above-mentioned problems, with which previously known systems are associated, are solved by the present invention by an apparatus according to the independent claim 1. In addition, a method and a computer program according to the invention are provided to solve related problems and make significant contributions.

Further technical effects of the invention appear from the dependent claims 2-14.

The core of the technical solution according to the invention is based on the use of small and easily accessible low-cost components for advanced tracking of sports-related actions and events (so-called sports tracking). This is done by controlling a camera sensor's image capturing properties (gain, framerate, exposure time, cropping, resolution, etc.), in a way that has not been done before in the field of racket sports. Racket sports offer limited space and limited possibilities for setting up camera tracking or tracing, which distinguishes the area from many other possible applications or from other solutions presented in related technical areas.

By using small components, the equipment can be placed in a way that does not interfere with the game. This is done, for example, by placing the camera equipment in a way that makes the equipment an integral part of the net post/pole. By integrated is meant here that the equipment is functional and from a regular perspective is to be regarded as part of the net post/pole. This further means that its components and connections between the components are built into a thin, slender casing, which in turn is attached to at least one, but most likely in both net posts/poles. If possible, it is also conceivable that the equipment is built into the net post/pole, which applies to all racket sports, but perhaps especially for table tennis applications, so that the cover and the net post/pole are in one piece, i.e. housing and net post/pole are designed to be fully integrated with each other. Because the casing, as well as by extension the entire installation including components and other equipment, is so thin, the equipment does not interfere with the game in the sense that it intrudes on the track, or is otherwise incompatible with racket sports regulations or disturbs participants in practice. In accordance with an alternative embodiment, the equipment is designed as part of or an integral part of the referee's chair instead of as part of or in connection with the net post/pole. As the referee's chair in many cases, for example in tennis, is slightly raised in relation to the net post/pole, this can be an excellent alternative or complement to the net post/pole for mounting equipment according to the invention.

By using low-cost components, a high-performance user experience, often equivalent to the high precision achieved using the previously described and more advanced so-called tracking, can be provided at a significantly lower cost than existing solutions allow. The availability of components can also be expected to be relatively good and easy to secure for manufacturers of the device according to the invention. This is especially true compared to specialized high- cost components, such as more advanced printed circuit boards, microchips and processors, which are normally manufactured in smaller series and which are intended for specific applications where manufacturers in most cases must plan well to make orders well in advance.

Preliminary tests performed by the applicant indicate that the end user's experience of the present invention is excellent. The measured precision on tennis courts is significantly better than the human-assessed precision, and the average error in the assessments is only a few millimetres. As the distance between the optical equipment in, for example, a net post/pole and an impact area in racquet sports other than tennis is shorter, even better precision is expected to be achieved in the other racquet sports, such as padel, badminton, table tennis and squash.

By using low-cost components, the product can also be provided, not only at a lower price but also with a different business model than the one hitherto dominated in the market for systems with high performance, precision and reliability. As an example, systems with comparable precision (e.g. Hawk-Eye) utilise components at a significantly higher cost. A system like the above-mentioned is therefore typically offered at a cost of about 50000 EUR per installation. By comparison, the apparatus according to the present invention can be provided, either entirely or at least essentially, free of installation costs, and require a license fee to be paid by customers of only a few tens of EUR per month for the individual end user. This completely removes the entry barrier for sports and racket halls to be able to offer their customers, i.e. typically exercisers and other racket players as well as other stakeholders a significantly enhanced experience. The enhanced experience is achieved by providing the playing field or venue with a relatively advanced equipment for tracking and observing sports- related events at a virtually non-existent entry cost, whereby the need for significant amounts of restricted capital or utilisation of venture capital becomes significantly less, if not non existent, compared to previously known systems.

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 schematically shows different components that are included in the device and how they are connected to each other.

Figure 2 shows the device in the open condition with special focus on how the housing is shaped and how the bottom and lid parts of the housing are attached, preferably screwed together.

Figure 3 shows the bottom and lid of the device, illustrating the main printed circuit board and processor together with the data and network connection.

Figures 4 and 5 show the design, technical construction and dimensions of the main printed circuit board in top and bottom views, respectively.

Figures 6 and 7 show the design, technical construction and dimensions of the housing in top and bottom views, respectively.

DESCRIPTION OF EMBODIMENTS

For a description of various alternatives, examples and embodiments of the present invention, reference is made to the accompanying drawings.

Figure 1 is a schematic sketch of the various components included in the device and how they are connected to each other. A printed circuit board (PCB) is located centrally in the device, and is typically rectangular in shape with the sides 65 mm x 20 mm as dimensions. According to this particular embodiment, the mentioned dimensions are maximum dimensions, but for alternative embodiments, in particular with larger inner space, the dimensions may of course be altered in either directions. Mounted on this printed circuit board is a chip with a processor 20, from which a plurality of functions are controlled and controlled, such as camera control, data processing and synchronization of input and cooperating components. A USB connector 30 is provided at the main printed circuit board for connection to a power source, which power source can be both a mains connection and battery operation. Furthermore, one at least one camera module 40 is connected to the main printed circuit board, either directly or via a so-called flex-PCB connection 50, preferably including a first connector 55 for contacting the camera module or another sensor module.

According to an alternative embodiment of the device according to the present invention, a further camera module 60 is connected to the main printed circuit board. This too is then connected to the main printed circuit board via an additional flex-PCB connection 70 by means of a second connector 75 for different types of sensor modules. However, this second camera module is located at a distance from the main circuit board, so direct contact is not possible. The distance between the camera modules is preferably between 30 mm to a maximum of approximately 70 mm. The upper limit is due to practical limitations of separating the camera modules within the same installation, without the installation becoming awkward or too bulky, and thus incompatible with other dimensional limitations. Such limitations may for instance be applicable regulations in the context of competition for a particular racquet sport or other limiting or influencing factors to take into account. Needless to say, the mentioned distance may be varied both upwards and downwards, depending on the construction and space available, but also in dependence of other relevant restrictions.

As mentioned, the main circuit board can be used with both one and two camera modules. In addition, two camera modules from different main circuit boards can work together, which is made possible by synchronizing the various components. According to this embodiment, there is also a pin 80 (pin for camera sync) provided for the purpose on the main circuit board for clocking different units, i.e. synchronize different input devices in time, such as in the current case the two input camera modules. This allows the camera modules to be placed at longer distances from each other, whereby synchronization of the camera modules and the data processing from them is still possible, either via network, power or other cables or wirelessly via Wi-Fi connections or any other applicable communication protocol. A typical installation with cooperating camera modules which belong to different main printed circuit boards is in installations of equipment according to the invention in net posts/poles on both sides of the net, for example on a tennis court. Another advantage of having synchronized and cooperating camera modules at a relatively large distance from each other is that the precision can be improved by large triangulation angles, and that the combined field of view of the two camera modules becomes significantly larger than the corresponding field of view from two closer cameras, for example controlled from the same circuit board . It should also be mentioned in this context that synchronization of different camera modules with respect to time is not necessary for the equipment according to the invention to function. However, the synchronization can have an important functional significance for the invention, as the precision and thus the reliability of the equipment can be further improved by controlling the camera modules to cooperate in a time-synchronized manner.

According to yet another alternative embodiment of the invention, it is possible, as an alternative to one or two camera pairs operating in stereo, instead to connect four or more single cameras operating individually. In other words, utilization of mono units instead of stereo units would be both feasible and advantageous, whereby system flexibility can be even further enhanced.

Figure 2 shows the device in the open condition with special focus on how the housing is shaped and how the bottom and lid of the housing are attached, preferably screwed together. According to a preferred embodiment, the housing is a camera sensor cover, which is designed as a hard shell in impact-resistant material, for example hard plastic, composite material or metal. This is to protect against impacts, such as a direct ball hit, without adversely affecting the image quality, such as by at least partially obscuring the image, preventing sufficient light entry or otherwise interrupting the light path or otherwise obstructing optimal image capture.

In addition to what has been mentioned previously, it is also possible to activate and control the device by voice control to, for example, only receive support from the invention to determine whether a ball bounced on or off a line in doubtful cases. The dimensions in the drawings are stated to suit tennis and the dimensions that a regulated net post/pole in tennis must comply with. The dimensions are intended to be adapted to the dimensions and designs that other applicable racket sports allow. The drawings are thus to be regarded as schematic and intended to be adapted to each specific racket sport, including its specific equipment and rule collections, in which the device may be used.

Stored comparison data with which acquired information is intended to be compared with may consist of information and associated logic that interprets and classifies an object's appearance and movement pattern.

According to the present invention, the imaging properties of the camera sensor can be varied in different ways. An example previously mentioned is cropping, where an algorithm is used to select a smaller area of the camera sensor based on image information, which is analysed in detail by image processing while the rest of the camera sensor field is left completely without analysis or with only a more rudimentary analysis.

The resolution of the camera sensor can also be varied, whereby the same algorithm as above or a similar algorithm is used to treat a certain part of the area of the camera sensor in high resolution while another area is treated in lower resolution.

In both of the above cases, i.e. cropping and resolution, the purpose is to treat the most interesting and informative parts of the camera sensor area at high speed, while other areas are prioritized down. In this way, a good quality and precision can be achieved and maintained over time, even though the components used according to the invention can show significantly lower performance and price than other system components, which could be alternatives for creating comparable results in terms of precision and speed, but as previously discussed, must be excluded for purely practical reasons.

To further clarify what is meant by compliance with the rule, the term "compliant" means that with a typical net post/pole including equipment / cover according to the invention is still within the rules for what is the maximum permitted size for a tennis post (according to national and international tennis rules).

Functional compliance means that by being "compliant", the net post/pole, even with equipment / casing, still achieves the same functional purpose (with regard to the net post's/pole's function in the game, the net post's/pole's location on the court, and the possibility to adjust the tension of the net and finally to mount / dismount the net post/pole and the net).