Tracking system and method of operation thereof

Abstract

A method of operating a motion tracking system for tracking a position of an object moving around a play area includes: arranging at least three tracking devices around the play area, where each tracking device includes a linear distance measurement unit; a reference device is positioned at least at a first position, where the reference device comprises a linear distance measurement unit, and where at least the first position has a known relationship to a first reference point in the play area, where the reference point is located in the play area. A linear distance measurement unit configured to allow measurement of linear distances between each tracking device or reference device and at least three other tracking devices and / or reference devices; calculating, for each tracking device and reference device, linear distances between the tracking device or reference device and at least three other tracking devices and / or reference devices using a linear distance measurement unit to create a set of linear distance measurements; creating a device topology of the at least three tracking devices based on the linear distance measurement set; and determining an arrangement of the device topology relative to the competition area based on the linear distance measurements to the at least first position and a known relationship of the at least first position to the first reference point.

Description

Technical Field

[0001] The present application relates to a tracking system for tracking the position of an object moving around a tracking area and a method of operating the same. In particular, the present application relates to a motion tracking system for tracking the position of an object such as a player or a ball moving around a playing area, in particular around a sports field. Background Art

[0002] In many conventional tracking systems, a network of fixed or mobile tracking devices, often referred to as "anchors," are used to locate multiple mobile devices, the fixed or mobile tracking devices often being referred to as "tags." An example of such a tracking system is an ultra-wideband (UWB) tracking system, which utilizes an array of UWB anchors to track the location of one or more UWB tags using distance measurements that may utilize radio frequency messages. However, in order to accurately track the location of a tag using the anchor devices, the relative locations of the anchor devices, i.e., the device topology, must be known, and their absolute locations must be known relative to the coordinate system in which the tag is to be tracked.

[0003] In many applications, a coordinate system for the tracking area is established using well-known surveying techniques and equipment. One standard piece of surveying hardware is a total station, which can locate objects to millimeter or even sub-millimeter accuracy. After installing fixed UWB anchors around the tracking area, a total station is used to establish a coordinate system, and then the position of the fixed anchor is determined relative to the coordinate system.

[0004] With the coordinate system established with a high degree of accuracy and the known anchor positions, the position of the tag relative to the established coordinate system can be calculated using a variety of techniques known to those skilled in the art, such as multilateration.

[0005] As an example, in sports applications, anchors are often installed in stands in stadiums, particularly under I-beams supporting seating layers. For these fixed installations, it is efficient to use a total station to very accurately determine the anchor position after installation, because the process only needs to be performed once, and the device will not move for many years. However, there are situations where the use of a total station (or other equivalent measurement techniques) is too expensive, cumbersome, and limited. For example, this technology is impractical for systems that need to be transportable and can be deployed quickly. Alternatively, for anchors installed around a training ground, since the field lines of the training ground are regularly redrawn, the anchors also need to be regularly recalibrated, which is both costly and increases the operational burden. In addition, if the anchor position has changed, such as being moved by maintenance personnel, or the fixture to which it is attached has been moved, the entire system needs to be recalibrated before being used again, otherwise the data will be biased due to inaccurate anchor positions.

[0006] While UWB was specifically mentioned above, the same set of issues can be applied to camera tracking systems that use a combination of video and computer vision algorithms to track objects of interest. If the camera is moved for any reason, the entire system needs to be recalibrated.

[0007] It would therefore be desirable to provide a faster, more convenient and cost-effective solution for operating a tracking system. Summary of the invention

[0008] According to a first aspect of the present application, a method for operating a tracking system, in particular a motion tracking system, for tracking the position of an object moving around a tracking area, in particular a playing area, is provided, the method comprising: arranging at least three tracking devices around the tracking area, wherein each tracking device comprises a linear distance measurement unit; positioning a reference device at least at a first position, wherein the reference device comprises a linear distance measurement unit, and wherein at least the first position has a known relationship with a first reference point in the playing area; wherein the linear distance measurement unit is configured to allow measurement of a linear distance between each tracking device or reference device and at least three other tracking devices and / or reference devices; for each tracking device and reference device, using the linear distance measurement unit to calculate the linear distance between the tracking device or reference device and at least three other tracking devices and / or reference devices to create a set of linear distance measurements; based on the set of linear distance measurements, creating a device topology of at least three tracking devices; and determining the arrangement of the device topology relative to the playing area based on the linear distance measurements to at least the first position and the known relationship of at least the first position to the first reference point.

[0009] The method uses linear distance measurement units positioned on the tracking device itself to establish the relative position of the tracking device and create a device topology. As will be discussed in more detail below, each linear distance measurement unit is typically a transmitter and / or a receiver, so that a pair of said linear distance measurement units allows the linear distance between the pair to be measured. The device topology established using the linear distance measurement set is fixed to the coordinate system by positioning a reference device at a reference position within the tracking area, and using, for example, a linear distance measurement unit of the tracking device to measure the distance to the reference position. In a particularly preferred embodiment, the device topology is created and then fixed relative to the playing area; however, the device topology can also be created in a reference frame that has been fixed to the playing area, that is, by using one or more reference devices in the starting set of devices when creating the topology. The present technology prioritizes convenience over accuracy by making the tracking device itself contribute to the measurements used to establish the device topology and its position relative to the coordinate system in which the object is to be tracked. The result is a tracking system that is simple, cost-effective, and can be quickly set up and operated, and therefore allows for large-scale rapid deployment and recalibration of the tracking system.

[0010] The tracking device is typically arranged to have an unknown position, such as any convenient position around the playing area (although this is not required). In contrast, the reference device(s) are positioned at at least partially predetermined positions such that there is a predetermined known relationship between the position of the reference device and one or more reference points and / or reference directions in the playing area, as will be described in more detail below. In other words, the known relationship should be predetermined, that is, it should be known without linear distance measurements.

[0011] The present technology is preferably a method of operating a motion tracking system for tracking the position of an object moving around a playing area such as a sports field. However, this technology can also be used for other types of tracking systems, such as warehouses, concerts or studios, etc. In the motion tracking system, preferably, multiple tracking devices (most preferably each tracking device) will be arranged outside the playing area, such as outside the sports field. However, as an alternative, for example, the tracking device can be positioned above the sports field.

[0012] The tracking devices here each include a linear distance measurement unit that allows the measurement of the measured linear distance between each tracking device or reference device and at least three other tracking devices and / or reference devices. It should be understood that the present application can be used with more than three tracking devices (and in fact this will be preferred); however, in many settings, especially around a sports field, if it is assumed that these settings are arranged in a single plane, then three tracking devices are sufficient to establish a device topology and thus track objects around the tracking area. In the case of using more than three tracking devices, each tracking device will typically have a linear distance measurement unit to allow the linear distance to each other tracking device and reference device to be measured; however, the topology can still be established without measurement between each of the tracking devices and each other device. In the case where the tracking devices are not arranged in the same plane, that is, as objects tracked around the playing area, at least four tracking devices will be preferred, wherein each tracking device includes a linear distance measurement unit that is configured to allow the linear distance to at least three, preferably at least four other tracking devices and / or reference devices to be measured, although they usually measure the linear distance to each other's tracking devices and reference devices again.

[0013] The technique also includes positioning a reference device at least at a first position, and measuring a linear distance to the first position using a linear distance measurement unit. As described above, the first position should be at least partially predetermined. For example, the user of the system may be instructed to position the reference device on a specific field marker or somewhere along one of the field lines of the sports field. This is because this step is used to obtain information about the device topology related to the first reference point in the tracking area in order to establish the position of the tracking device relative to the coordinate system in which the object is to be tracked. It should be noted that at least the first position has a predetermined "known relationship" with the first reference point, which means that the position may not correspond to the first reference point, but will provide information about the position of the first reference point. For example, the first position may be on the first reference point, or offset from the first reference point by a known distance, and this factor may be taken into account when determining the arrangement of the device topology relative to the tracking area. Alternatively, if multiple reference devices are used, the two reference devices may be positioned so that the first reference point is located at the center point between the devices. This is why only at least the first position measured with the reference device needs to have a known relationship with the first reference point, that is, if there is more than one first position, these positions together may have a known relationship with the first reference point.

[0014] By providing a reference device at a first position having a (predetermined) known relationship to at least a first reference point in the tracking area, this may allow the device topology to be accurately mapped to the coordinate system of the tracking area.

[0015] In some particularly preferred embodiments, the setup is divided into two distinct phases, wherein a topology of tracking devices is established in an arbitrary reference frame without a reference device, and then the arrangement of the device topology relative to the tracking area is determined using linear distance measurements calculated for the reference device(s). For example, the method may include: arranging at least three tracking devices around the tracking area, wherein each tracking device includes a linear distance measurement unit configured to measure linear distances to at least two other tracking devices of the at least three tracking devices; for each tracking device, using the linear distance measurement unit to calculate the linear distance between the tracking device and the at least two other tracking devices to create a set of linear distance measurements; based on the set of linear distance measurements, creating a device topology of the at least three tracking devices; positioning the reference device at least at a first position, wherein at least the first position has a known relationship to a first reference point in the tracking area; calculating the linear distance between each of the at least three of the tracking devices and the reference device at the first position to create a set of reference measurements; and determining the arrangement of the device topology relative to the tracking area based on the set of reference measurements.

[0016] It should be understood that the above generally describes a method of setting up or calibrating a motion tracking system. The method of operating a motion tracking system generally further comprises: after the above steps, tracking one or more objects (preferably mobile electronic devices, i.e. tags) around a playing area using at least three tracking devices, preferably using linear distance measurement units of at least three tracking devices.

[0017] In some embodiments, one reference device may be all that is needed to determine the arrangement of the device topology relative to the tracking area. For example, if the tracking area is circular with rotational symmetry about a center point, a single reference device may be mounted at the center point to determine the arrangement of the device topology relative to the tracking area. This may require one or more assumptions, such as assuming that the tracking device is arranged in a plane parallel to the ground plane of the tracking area. In other embodiments, the reference device may include a device for identifying its orientation. For example, an embodiment using a UWB transceiver with multiple antennas to allow the use of a phase difference of arrival (PDOA) or an angle of arrival (AOA) to determine the orientation will be described below. The reference device may then be configured to be mounted at a position where its orientation is aligned with one or more reference directions of the tracking area, and the arrangement of the device topology relative to the tracking area may then be determined using measurements of the linear distance to the reference device and its orientation relative to the device topology. For example, if the tracking area is an athletic track, the reference device may be positioned at the center of the athletic track and aligned with the longer dimension of the athletic track to allow the arrangement of the device topology relative to the athletic track to be determined.

[0018] While in some cases only one reference device may be used to determine the arrangement of the device topology relative to the tracking area, most embodiments preferably include positioning a reference device at each of at least a first location and a second location, wherein at least the first location and the second location together have a known relationship to a first reference point in the tracking area and a second reference point or a first reference direction in the tracking area, and wherein determining the arrangement of the device topology relative to the playing area is based on linear distance measurements to the first location and the second location and the known relationship of the first location and the second location to the first reference point and the second reference point or the first reference direction. For example, this may include calculating a linear distance between each of at least three of the tracking devices and the reference device at the second location. This provides greater flexibility and greater accuracy in determining the arrangement of the device topology relative to the tracking area. As will be discussed below, where reference devices are required at the first location and the second location, this may include one reference device positioned at the first location and the second location, or two reference devices positioned at the first location and the second location, respectively.

[0019] Likewise, at least the first position and the second position should each be at least partially predetermined, and together may have a (predetermined) "known relationship" to the first reference point and the second reference point. The first position and the second position will preferably coincide with the first reference point and the second reference point, but there may also be a known offset. In one example, for a soccer field of known size, it may be predetermined that the reference device should be positioned at two penalty spots, so that the position of the tracking device relative to the field can be determined using measurements between the tracking device and the first reference point and the second reference point. In addition, at least the first position and the second position together may have a "known relationship" to a first reference direction. The devices may be spaced apart along the direction of the reference direction, such as along one of the field lines, but if desired, may also be at some known angle to the reference direction, such as perpendicular to the field lines. In a second example, for a football field of known size, one reference device may be positioned at a corner of the touchdown line and the sideline, and another reference device may be spaced apart from the first reference device along the sideline. This may provide: information about the reference point, i.e. the corner of the touchdown line and the sideline; and information about the reference direction, i.e. the direction of the sideline, i.e. the direction along which the two reference devices are spaced apart. It should be understood that these are just two examples given in a specific motion scenario, and that virtually any system of reference points for locating the device topology relative to a reference in the coordinate system used for tracking may be used.

[0020] Although in some cases the system may be set up with two reference devices, in many cases it is preferred to extract information about the tracking area by using more reference devices. Thus, preferably the method comprises positioning the reference device at a third position at least partially predefined such that the first position, the second position and the third position are not arranged in a straight line, wherein preferably the third position and the first position and / or the second position together have a known relationship to a second reference direction in the tracking area, and wherein determining the arrangement of the device topology relative to the playing area is based on a linear distance measurement to the third position and a known relationship of the third position and the first position and / or the second position together to the second reference direction, and wherein preferably determining the arrangement of the device topology relative to the tracking area is also based on the order of the first position, the second position and the third position. In many applications, measurements of the reference device at the third position are required in order to properly orient the device topology to the area of ​​interest, such as a sports field. For example, three positions that are not in a straight line may allow the system to identify a plane, such as the plane of a sports field, regardless of the arrangement of the device topology relative to the plane. Measurements of the reference device at the third position may also allow the system to identify a second reference direction in the tracking area. To continue with the football field example mentioned earlier, a third position can be located somewhere along the touchdown line, so that the first position at the corner of the touchdown line and the sideline, together with the third position, enables the system to identify the direction of both the touchdown line and the sideline. A series of three positions can also transmit information through the order of these positions, for example in a manner similar to the "right hand rule". This can be used to enable the three positions to be used to measure a plane, such as a ground plane, and the order of these positions is used to identify which direction is the upward direction perpendicular to the plane. It should be noted that, as an alternative, the order of the tracking devices themselves can be used to determine the arrangement of the device topology relative to the tracking area. For example, each tracking device can be numbered, and the setup can require positioning the tracking devices clockwise around the playing field and then determining the upward direction in a manner similar to the "right hand rule". Again, in these examples, there can be a separate reference device located at each position, or one or more reference devices can be moved sequentially between positions so that measurements are made of the positions using fewer reference devices.

[0021] As described above, the first position, the second position and the third position preferably define a plane substantially parallel to the ground plane level in the tracking area, such as a sports field. This allows the system to identify the plane of the sports field. For example, the reference device or each reference device may be positioned substantially on the ground plane. Alternatively, one or more reference devices may be positioned at a known height above the ground plane. For example, one or more reference devices may be set on a support with a known height, such as a tripod. In order to identify the ground plane, the system may need to take the known height of the reference device into account when utilizing the measurements of the reference device.

[0022] In many embodiments, the first reference point is a noteworthy point in the coordinate system in which the object is to be tracked. For example, the first reference point can be the intersection of the midfield line and the sideline in a rugby field. A preferred way to obtain information about the reference point is to set the first position to have a known positional relationship with the first reference point, wherein most preferably, the first position substantially coincides with the first reference point. The reference device does not need to be actually positioned at the first reference point, although this is preferred. For example, if a game is currently in progress, it may be necessary to position the reference device at a position 5 meters from the reference point. However, if the offset is known, the reference point can still be identified using the measurement of the reference device at the first position. It should be noted that it is not necessary to position a reference device with a known positional relationship with the first reference point. For example, two reference devices can be arbitrarily spaced apart along the midfield line of the rugby field, and two reference devices can be arbitrarily spaced apart along the sideline. In this case, the reference position, i.e., the intersection of the two lines, can be determined based on a combination of positions, because the direction of the two lines can be determined based on the reference measurement.

[0023] Regardless of how the reference device(s) are positioned, at least one dimension of the tracking area is preferably also measured using linear distance measurements to the reference positions. It should be noted here that this may include linear distance measurements made between reference devices at at least a first position and a second position. That is, the dimensions may be measured by linear distance measurements from the tracking device to the reference device, or based on linear distance measurements directly between the reference devices, or some combination thereof. The dimensions may be measured by ensuring that at least the first position and the second position have in common a (predetermined) "known relationship" about the dimension to be measured. The dimensions may then be determined by the distances between the positions for the reference device(s).

[0024] In addition, preferably, the second position has a (predetermined) known positional relationship with a second reference point in the tracking area, wherein preferably, the second position substantially coincides with the second reference point. Continuing the above football field example, the second reference point may be the intersection of the same sideline and the touchdown line. Again, the reference device may be positioned to coincide with the reference point, or may be spaced a known distance from the reference point. An advantage of a system that requires the user to position a reference device with a known positional relationship relative to two or more reference points is that at least one dimension of the tracking area can be conveniently determined based on a set of linear distance measurements. Continuing the football field example, the system is then able to measure the distance between the midfield line and the touchdown line, thereby gaining a more accurate understanding of the tracking area. This is superior to, for example, assuming standard field dimensions or requiring the user to enter specific field measurements separately. In another preferred embodiment, the third position has a known positional relationship with a third reference point in the tracking area, wherein preferably, the third position substantially coincides with the third reference point. Continuing the football field example again, the third reference point may be the intersection of the opposite sideline and the 22-meter line. This goes a step further on the above advantages, and allows further measurements about the field to be made during setup. As described above, another alternative to positioning a reference device with a known position relative to a reference point is to rely on a combination of reference devices to provide information about one or more reference points and a reference direction. For example, if a pair of reference devices are arbitrarily spaced along each site line, this will allow identification of reference points and measurement of distances between these reference points or between site lines in order to measure the site. Therefore, in the general case, at least the first position and the second position together may have a (predetermined) "known relationship" about the dimension to be measured, as described above. However, this may require the use of reference devices at more locations in order to obtain the same information about the site.

[0025] As described above, in addition to obtaining information about reference points in the tracking area, it may be desirable to identify a reference direction in the tracking area. This may be achieved by having a first position and a second position have a (predetermined) known angular relationship to a first reference direction, wherein preferably the first position and the second position define a line that is substantially parallel to the first reference direction. It should be noted here that a line parallel to the first reference direction is considered to include a line that coincides with the reference direction. For example, if the reference direction is considered to be defined by one of the sidelines, the first position and the second position may be arranged along the sideline. Typically, it is easiest for a user to position a reference device along a reference direction, such as positioning a reference device along a field line of a sports field. However, assuming that the angle relative to the reference direction is known, this may provide sufficient information to identify the reference direction in the tracking area.

[0026] As can be clearly seen from the above discussion, in the most preferred examples, the reference points and reference directions mentioned correspond to the field markings of the sports field in the tracking area. More generally, the first reference point and / or the second reference point (and / or any third reference point or other reference point) can correspond to the field markings on the sports field in the tracking area. Preferably, the first reference point and / or the second reference point (and / or any third reference point or other reference point) correspond to the intersection of at least two field lines on the sports field, and / or wherein the first reference direction corresponds to the direction of the field line on the sports field. The exemplary reference points that have been given include the penalty points of a soccer field, or the intersection of the midfield line and the sideline of a rugby field, but it is obvious that when establishing a coordinate system in which an object is to be tracked, any field marking can be used as a reference point, and further, the direction of any field line can correspond to the reference direction in the coordinate system. Preferably, the linear distance measurement set is also used to measure one or more dimensions of the sports field, such as using linear distance measurements to the first position and the second position.

[0027] In a particularly preferred example, the first position is at the intersection of at least two field lines on the sports field in the tracking area, and the second position is positioned along one of the two field lines from the first position, wherein preferably the second position is at the intersection of a third field line with one of the at least two field lines, so that at least one dimension of the sports field can be determined based on linear distance measurements to the first position and the second position. As already noted, the reference device can be mounted directly on the field or can be supported above the field, for example on a tripod. This represents a particularly convenient way of determining the arrangement of the device topology relative to the tracking area and the measurement of one or more dimensions of the field, since the user only has to position the reference device(s) at certain positions on the field lines, which is easy for the user to understand and perform.

[0028] As has been briefly noted above, the technique can include using any number of reference devices for an array of locations where reference measurements are to be obtained. For example, a first reference device can be positioned at a first location and a second reference device can be positioned at a second location, or a first reference device can be positioned at a first location and then, after calculating the linear distance between each of at least three of the tracking devices and the first reference device at the first location, the first reference device can be positioned at the second location. The linear distance between each of at least three of the tracking devices and the first reference device at the second location can then be calculated, and the set of linear distance measurements updated. When additional locations are used, this principle can be extended to any location between one reference device and the same number of reference devices as the number of reference locations used (i.e., one reference device per location).

[0029] In a particularly preferred embodiment, one or more or each of the reference devices is an additional tracking device, and further comprising: after obtaining a linear distance measurement to the corresponding at least first position, arranging the reference device or each reference device around the tracking area, using one or more linear distance measurement units, calculating the linear distance between the additional tracking device or each additional tracking device and at least three of the at least three tracking devices, and updating the device topology to include the additional tracking device or each additional tracking device. In these embodiments, once the reference device is used to determine the arrangement of the device topology relative to the tracking area, the reference devices can each be used as a tracking device. For example, the reference device can be substantially the same hardware as the tracking device. In order to do this, once the linear distance measurement to the reference device position has been obtained, the device topology must be updated to include the reference device; however, at this stage, the arrangement of the device topology to the tracking area is known, so the reference devices are no longer needed for their original function. It should be understood that the tracking capability will be enhanced by additional tracking devices, and that this embodiment makes the most effective use of the hardware used to set up the tracking system. Although the reference devices can be additional tracking devices, they can also be "tags", that is, mobile devices that are usually tracked by tracking devices.

[0030] In some embodiments, wherein one or more of the tracking device and / or the reference device includes a GNSS receiver configured to make GNSS position measurements of the device, and wherein determining the arrangement of the device topology relative to the tracking area is also based on the GNSS position measurements. There are many advantages to using GNSS position measurements simultaneously. For example, GNSS position measurement data can be used for initial coarse alignment of the device topology with the tracking area, or the data can be fused with linear distance measurement data to provide a more accurate coordinate system.

[0031] The method may be performed by a controller, and measurements from each tracking device and / or reference device may be transmitted to the controller, which may then calculate linear distances based on the measurements received from the tracking devices (and reference devices), as well as create a device topology, and determine the arrangement of the device topology relative to the tracking area.

[0032] A problem with conventional tracking systems is that when one of the tracking devices moves, the entire system will need to be recalibrated before it can be used again, otherwise the inaccurate position of the tracking device will cause data errors. Therefore, preferably, the method includes: after creating the device topology, detecting the movement of one of the at least three tracking devices (preferably at least four tracking devices) relative to the other tracking devices of the at least three (preferably at least four) tracking devices, using a linear distance measurement unit to recalculate the linear distance between the moving tracking device and each of the at least two (preferably at least three) other tracking devices of the at least three (preferably at least four) tracking devices, and updating the device topology to take into account the movement of the moving tracking device based on the recalculated linear distance between the moving tracking device and each of the at least two (preferably at least three) other tracking devices of the at least three (preferably at least four) tracking devices. That is, because in the present system, the tracking devices are able to measure the distance between each other, they are able to automatically update the device topology without the need to use the measuring device again as in conventional systems. This part of the method usually occurs after the initial calibration, for example after the reference device is removed, so in order to most accurately reposition the moving tracking device, preferably, the method includes at least four tracking devices.

[0033] The method may include, for each tracking device, periodically recalculating the linear distance between the tracking device and at least two other (preferably at least three other) tracking devices using a linear distance measurement unit, and detecting movement of one of the at least three tracking devices based on changes in the linear distance between the moving tracking device and the at least two other tracking devices detected after the recalculation. In other words, the tracking device frequently checks the linear distance to the other tracking devices in order to identify when a device has moved. This will be visible in the data because one device will detect movement of all other devices it is measuring, while the other devices will only detect movement of the one tracking device. Additionally or alternatively, each tracking device may also include one or more of an accelerometer, a gyroscope, and a magnetometer, and detecting movement of one of the at least three tracking devices relative to the other tracking devices is based on readings from the accelerometer, gyroscope, and / or magnetometer. It should be noted that including these sensors in the tracking device also has other advantages. For example, in some applications, it may be necessary to identify the north-south direction in a coordinate system, and a magnetometer can achieve this. These sensors will also allow for some form of dead reckoning so that the position of a device within the topology can be updated even if measurements to other tracking devices are obstructed, such as if line of sight is blocked.

[0034] The linear distance measurement unit can generate a particularly accurate device topology when the positions of the tracking devices vary in three-dimensional space, i.e., not all within substantially the same plane, so that multiple measurements can be made for each device from significantly different directions. Similarly, when all tracking devices are located within a single plane, such as when all tracking devices are located at the same height above a sports field, the linear distance measurement unit can generate an accurate device topology. However, due to the infrastructure surrounding the tracking area, it is very common to have small height differences between tracking devices, which can introduce significant inaccuracies in the device topology. For example, if the tracking devices are all located within substantially the same plane, but have a height difference of up to, for example, 1 meter, such height differences are difficult to accurately discern and incorporate into the device topology when measuring linear distances at, for example, 200 meters. Therefore, preferably, each tracking device also includes a pressure sensor configured to measure the air pressure at the location of the tracking device, and the method also includes: calculating the relative height of each tracking device based on the air pressure measured at the location of each tracking device, and wherein creating the device topology is also based on the calculated relative height of each tracking device. The or each reference device may also include a pressure sensor configured to measure the air pressure at the location of the reference device. In this embodiment, the relative altitude may be derived with reasonable accuracy from the air pressure measurement at the tracking device.

[0035] The method may also include determining the absolute altitude of each of the tracking devices. In practice, this may include providing one or more tracking devices (or reference devices) with known altitudes, and then comparing the pressure readings of each tracking device with the pressure readings of the known devices to determine the absolute altitude of each device.

[0036] Preferably, the one or more reference devices further comprise a pressure sensor configured to measure air pressure at the location of the reference device, and determining the arrangement of the device topology relative to the tracking area is further based on the pressure measurements of the tracking device and the pressure measurements of the one or more reference devices. Alternatively, the heights relative to each other may be determined only between the tracking devices, such that the device topology reflects the changes in height, and then the device topology relative to the reference device is determined using the linear distance measurements to the reference location.

[0037] For the above embodiments, it should be noted that pressure naturally varies over time, and this will affect the pressure measurements made by the devices. Therefore, it is preferred that each pressure reading be taken at the same time interval, preferably a known time interval, such as within two minutes. For example, the reading of one device (or an average of several devices) within that time interval can then be subtracted from the pressure reading of each tracking device, which devices preferably have known altitudes, to eliminate the natural variability of atmospheric pressure, leaving only the difference caused by the difference in altitude of the tracking devices.

[0038] The use of pressure sensors is preferably arranged in a method comprising arranging at least four tracking devices around the tracking area, wherein each tracking device is arranged substantially in the same plane within a tolerance of 10 meters, preferably within a tolerance of 5 meters, more preferably within a tolerance of 2 meters, most preferably within a tolerance of 1 meter, and wherein, preferably, the tracking devices are arranged at least 50 meters apart, preferably at least 70 meters apart, more preferably at least 100 meters apart. That is, the use of pressure sensors becomes more valuable as the height difference between the tracking devices becomes smaller, that is, it becomes more difficult to measure from a linear distance measurement, and becomes more valuable as the distance between the tracking devices becomes larger, that is, the effect on the distance caused by the height change has a smaller proportional effect on the total measured distance.

[0039] In many embodiments, the linear distance measurement unit of each tracking device is further configured to allow measurement of the linear distance between each tracking device and one or more mobile electronic devices moving around the tracking area.Such systems are particularly advantageous because they make dual use of the linear distance measurement units.

[0040] The linear distance measurement unit of each tracking device preferably includes an ultra-wideband (UWB) transmitter and / or receiver, which will include the use of a UWB transceiver. Preferably, each tracking device includes a UWB transmitter and receiver so that each tracking device can measure the linear distance to each other tracking device. Other suitable linear distance measurement devices include, for example, lidar, ultrasonic and laser rangefinder units. UWB transmitters and / or receivers are examples of linear distance measurement units, which can also measure the distance to a corresponding electronic device that can move through the tracking area.

[0041] Preferably, the linear distance measurement unit of at least one tracking device comprises at least a first antenna and a second antenna for performing linear distance measurements, and further comprises calculating the relative orientation of the at least one tracking device using the linear distance measurements obtained with the first antenna and the second antenna. Preferably, a plurality of tracking devices, preferably each tracking device, each comprises at least a first antenna and a second antenna, so that an angular orientation can be determined for each of these tracking devices. As described above, the reference device can be configured identically to the tracking device, and thus one or more reference devices, preferably each reference device, can have at least a first antenna and a second antenna, and the method can comprise calculating the angular orientation of the reference device or each reference device relative to one or more tracking devices. This orientation of the (one or more) reference devices can be used to determine the arrangement of the device topology relative to the tracking area. The use of at least two antennas can allow, for example, the determination of the orientation using a phase difference of arrival (PDOA) or an angle of arrival (AOA) measured with the linear distance measurement unit. Two antennas can allow the determination of the angular orientation in two-dimensional space, for example, if all devices are positioned in the same plane. Three antennas can be preferred to allow the determination of the orientation in three-dimensional space.

[0042] Although antennas may be preferred for determining orientation, in other embodiments, at least one tracking device includes a plurality of linear distance measurement units, and the method further includes calculating a linear distance between each of the plurality of linear distance measurement units on the at least one tracking device and at least one other tracking device, and calculating the relative orientation of the at least one tracking device based on the difference in the calculated linear distances. Likewise, preferably, a plurality of tracking devices, preferably each tracking device, each includes a plurality of linear distance measurement units, so that an orientation can be determined for each of these tracking devices. Again, the reference device may be constructed in the same manner to allow their orientation to be determined. In this case, the orientation is determined based on the difference in linear distance measurements. For example, if a first linear distance measurement unit on one of the tracking devices is measured to be closer to the other tracking device than a second linear distance measurement unit on the tracking device, it may be determined that the tracking device is oriented so that the first linear distance measurement unit is located on the side closer to the other tracking device. Likewise, two linear distance measurement units on each tracking device may allow orientation to be determined in two-dimensional space, for example, if it is known that all devices are positioned in the same plane with their linear distance measurement units. However, preferably, three linear distance measurement units are provided on each tracking device to allow orientation to be determined in three-dimensional space.

[0043] In other examples, one or more tracking devices include a camera for optically tracking the position of an object moving around a tracking area. In particular, in various sports scenarios, it is known to use several cameras to track objects in three-dimensional space. In these embodiments, the distance between the tracking devices still has to be measured using a linear distance measurement unit, for example using a UWB transmitter and / or receiver. It is particularly preferred that the tracking device includes a camera to allow the orientation of the tracking device relative to other tracking devices to be determined, for example using the above-mentioned techniques. This is because tracking an object with a camera generally requires knowing the orientation of each camera. Therefore, in the case where one or more tracking devices include a camera, preferably, each of those tracking devices having a camera includes a linear distance measurement unit having at least a first antenna and a second antenna, or includes at least two linear distance measurement units.

[0044] Preferably, arranging at least three tracking devices around the tracking area comprises positioning each tracking device fixedly around the tracking area. This is in contrast to systems that use UWB transmitters and / or receivers that move around the tracking area, for example attached to an object such as a player or a sports ball. For example, the tracking devices may be attached to infrastructure around the tracking area, or be disposed on a fixed support structure, such as a tripod, that remains in place throughout the tracking process. Preferably, each of the at least three tracking devices remains stationary during one or more subsequent steps of tracking the position of an object moving around the playing area.

[0045] As described above, preferably more than three tracking devices will be used in order to improve the accuracy of the tracking process and to introduce redundancy in the number and positioning of the tracking devices. Preferably, the method comprises arranging at least four tracking devices around the tracking area, preferably at least six tracking devices, more preferably at least ten tracking devices, wherein preferably each tracking device comprises a linear distance measuring unit, which is configured to allow the linear distance to at least three other tracking devices to be measured. When the object to be tracked is not essentially confined to a plane like a player on a sports field, a system with four tracking devices that measure the distance to three other tracking devices is particularly useful. For more tracking devices, it is still only necessary to measure the distance to three other tracking devices, but typically each tracking device will include a linear distance measuring unit, which is configured to allow the linear distance to each other tracking device to be measured.

[0046] When four or more tracking devices are used, creating a device topology of at least four tracking devices based on a set of linear distance measurements preferably includes: identifying a starting set of three tracking devices and / or reference devices based on the magnitude of the linear distance measurements in the set of linear distance measurements and the difference between the linear distance measurements; defining a coordinate system using the linear distance measurements between each of the starting set of tracking devices and / or reference devices; and then, positioning a fourth tracking device or reference device in the coordinate system defined for the starting set of tracking devices and / or reference devices based on the linear distance measurements between the fourth tracking device or reference device and each of the tracking devices and / or reference devices in the starting set of tracking devices and / or reference devices. It is generally desirable to identify a starting set of three tracking devices and / or reference devices that define a relatively large and approximately equilateral triangle. This can be discerned from the magnitude of the linear distance measurements and the difference between the linear distance measurements. From this starting set, additional tracking devices and / or reference devices can be relatively accurately incorporated into the topology from a solid starting set of tracking devices and / or reference devices. When operating in three-dimensional space, as opposed to having the tracking devices and / or reference devices all in nearly the same plane, a starting set of defined tetrahedrons should be selected based on the magnitude of linear distance measurements and the difference between linear distance measurements, and then additional tracking devices and / or reference devices should be measured relative to the starting set and incorporated into the device topology.

[0047] Preferably, creating a device topology of at least four tracking devices comprises: creating a preliminary device topology using each of a plurality of different starting sets of at least three tracking devices and / or reference devices, preferably using each possible starting set of at least three tracking devices and / or reference devices, and creating a device topology using a plurality of preliminary device topologies, preferably by taking an average of the preliminary device topologies. If the one and only starting set of devices includes measurement errors, calibration performed in the above manner is prone to error propagation. To avoid this, the device topology can be created multiple times from a plurality of different starting sets as described above, and then the average is taken. Doing so can reduce the impact of measurement errors in the starting sets. It should be noted that the average value can be the average position or the median position of each device, with the median being more resistant to measurement errors.

[0048] In a particularly preferred embodiment, the method includes: comparing preliminary device topologies created from each starting set; based on the comparison results, ignoring one or more preliminary device topologies, the positions of one or more devices within the one or more preliminary device topologies, or one or more linear distance measurements; and creating a device topology using a plurality of remaining preliminary device topologies. In this embodiment, different preliminary device topologies are compared, and identifiable measurement errors are taken into account. In particular, the entire topology including the measurement errors can be ignored, the positions of individual devices within the device topology can be ignored, or it can be determined which (which) linear distance measurements lead to incorrect device positions, and the (which) measurements can be ignored and the preliminary device topology can be recalculated. For example, most preliminary device topologies may agree on relative device positions within a relatively small tolerance range, and therefore for any preliminary device topology, if one or more device positions included therein deviate from the average device position or from the device positions of a plurality of other preliminary device topologies by more than a threshold amount, such as 30 cm, preferably 20 cm, more preferably 10 cm, and even more preferably 5 cm, then this preliminary device topology can be ignored, or the device positions within the preliminary device topology can be ignored, or one or more problematic linear distance measurements can be ignored to remove measurement errors from the calibration process.

[0049] According to a second aspect of the present application, a method for operating a motion tracking system for tracking the position of an object moving around a playing area is provided, the method comprising: fixedly arranging at least three tracking devices around the playing area, wherein each tracking device includes a linear distance measurement unit, the linear distance measurement unit being configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices, wherein the at least three tracking devices have a known device topology; detecting movement of one of the at least three tracking devices relative to other tracking devices in the at least three tracking devices; using the linear distance measurement unit to calculate a linear distance between the moving tracking device and each of the at least two other tracking devices; and updating the device topology based on the calculated linear distance between the moving tracking device and each of the at least two other tracking devices in the at least three tracking devices to take into account the movement of the moving tracking device.

[0050] Compared to the first aspect of the present application, this may involve calibrating the system using conventional techniques, such as using a total station to calibrate the system. However, in this case, instead of recalibrating the system, the device topology is automatically updated if one of the tracking devices moves. In this case, the tracking accuracy will degrade over time, and periodic recalibration may still be required, but this technique will prevent inaccurate tracking results due to inaccurate tracking device positions.

[0051] The preferred features described above in relation to the first aspect are equally applicable to this aspect of the application. For example, this is also preferably a method of operating a motion tracking system for tracking the position of an object moving around a playing area such as a sports field, preferably using more than three tracking devices, the more than three tracking devices being configured to measure the linear distance to each other tracking device, and preferably using a linear distance measurement unit in the form of an ultra-wideband (UWB) transmitter and / or receiver.

[0052] In this aspect, each tracking device is fixedly arranged around the tracking area. For example, the tracking device can be fixed to the infrastructure around the tracking area, or be arranged on a fixed support structure, such as a tripod. This is in contrast to tags that can be attached to objects that move around the tracking area, such as players moving around a sports field. In fact, in a motion tracking system, each tracking device is preferably arranged outside the playing area, such as outside the sports field. In traditional tracking systems, fixed tracking devices are not expected to move, so any change in the position of one of these fixed anchors will destroy the tracking data. This is solved in this aspect by detecting the movement of one of the at least three tracking devices and updating the device topology accordingly. The method can be performed simultaneously with one or more steps of tracking the position of objects moving around the playing area.

[0053] The technique of updating the device topology to take into account the movement of one of the tracking devices is the same as described above. Preferably, detecting the movement of one of the at least three tracking devices includes: for each tracking device, using a linear distance measurement unit, periodically calculating the linear distance between the tracking device and at least two (preferably each) other tracking devices; and detecting the movement of one of the at least three tracking devices based on the change in the linear distance between the moving tracking device and the other at least two other tracking devices detected after the calculation. In other words, the tracking device frequently checks the linear distance to the other tracking devices in order to identify when one device has moved. This will be visible in the data because one device will detect the movement of all other devices it is measuring, while the other devices will only detect the movement of the one tracking device. In addition, or alternatively, each tracking device may also include one or more of an accelerometer, a gyroscope and a magnetometer, and detecting the movement of one of the at least three tracking devices relative to the other tracking devices is based on readings from the accelerometer, gyroscope and / or magnetometer.

[0054] As described above, each tracking device preferably also includes a pressure sensor configured to measure the air pressure at the location of the tracking device, and the method further includes: calculating the relative height of each tracking device based on the measured air pressure at the location of each tracking device, and wherein updating the device topology is also based on the calculated relative height of each tracking device. This may be particularly useful if the movement of the device includes raising or lowering the tracking device compared to other devices, especially if the tracking devices are substantially in the same plane.

[0055] According to a third aspect of the present application, a method for operating a motion tracking system for tracking the position of an object moving around a playing area is provided, the method comprising: arranging at least three tracking devices around the tracking area, wherein each tracking device comprises: a linear distance measurement unit, the linear distance measurement unit being configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices; and a pressure sensor, the pressure sensor being configured to measure the air pressure at the position of the tracking device; for each tracking device, using the linear distance measurement unit to calculate the linear distance between the tracking device and at least two other tracking devices to create a linear distance measurement set; based on the air pressure measured at the position of each tracking device, calculating a relative height of each tracking device; and creating a device topology of the at least three tracking devices based on the linear distance measurement set and the calculated relative height of each tracking device.

[0056] Likewise, the preferred features described above in relation to the first aspect are equally applicable to this aspect of the application. For example, this is also preferably a method of operating a motion tracking system for tracking the position of an object moving around a playing area such as a sports field, preferably using more than three tracking devices, the more than three tracking devices being configured to measure the linear distance to each other tracking device, and preferably using a linear distance measurement unit in the form of an ultra-wideband (UWB) transmitter and / or receiver.

[0057] Compared to the first aspect of the present application, this technique uses both linear distance measurements and pressure measurements to establish device topology, but the position of the device topology relative to a tracking area such as a sports field can be determined in any known manner, including by using a calibration device such as a total station.

[0058] As with the first aspect, the method may further include determining the absolute altitude of each of the tracking devices, for example by setting up one or more tracking devices (or reference devices) with known altitudes; and then comparing the pressure reading of each tracking device with the pressure reading of the known devices to determine the absolute altitude of each device.

[0059] Likewise, each pressure reading is preferably taken at the same time interval, preferably a known time interval, e.g., two minutes, and the reading of one device (or an average of several devices), preferably the known device, during that time interval can then be subtracted from the pressure reading of each tracking device to eliminate the natural variability in atmospheric pressure, leaving only the difference caused by the difference in altitude of the tracking devices.

[0060] As described above, preferably, the method comprises arranging at least four tracking devices around the tracking area, wherein each tracking device is arranged in substantially the same plane within a tolerance of 10 meters, preferably within a tolerance of 5 meters, more preferably within a tolerance of 2 meters, most preferably within a tolerance of 1 meter, and wherein preferably, the tracking devices are arranged at least 50 meters apart, preferably at least 70 meters apart, more preferably at least 100 meters apart.

[0061] According to a fourth aspect of the present application, a motion tracking system for tracking the position of an object moving around a playing area is provided, the system comprising: at least three tracking devices configured to be arranged around the playing area, wherein each tracking device comprises a linear distance measurement unit; a reference device comprising a linear distance measurement unit, wherein the linear distance measurement unit is configured to allow measurement of a linear distance between each tracking device or reference device and at least three other tracking devices and / or reference devices; and a data processing device configured to create a device topology for the at least three tracking devices based on a set of linear distance measurements, the linear distance measurement set comprising linear distance measurements between the tracking device or reference device and at least three other tracking devices and / or reference devices calculated for each tracking device and reference device using the linear distance measurement unit; wherein the data processing device is further configured to receive linear distance measurements of a reference device positioned at least at a first position, wherein at least the first position has a known relationship with a first reference point in the playing area, and further configured to determine the arrangement of the device topology relative to the playing area based on the linear distance measurements to at least the first position and the known relationship between at least the first position and the first reference point.

[0062] This corresponds to a system suitable for use with the method according to the first aspect of the application. Therefore, all preferred features described above in relation to the first aspect also apply to the system according to this aspect.

[0063] According to a fifth aspect of the present application, a motion tracking system for tracking the position of an object moving around a playing area is provided, the system comprising: at least three tracking devices configured to be arranged around a playing area having a known device topology, wherein each tracking device comprises a linear distance measurement unit configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices to create a linear distance measurement set; and a data processing device configured to detect movement of one of the at least three tracking devices relative to other tracking devices of the at least three tracking devices, and to update the device topology based on the linear distance measurement set to take into account the movement of the moving tracking device.

[0064] This corresponds to a system suitable for use according to the method of the second aspect of the present application. Likewise, all the preferred features described above also apply to this system.

[0065] According to a sixth aspect of the present application, a motion tracking system for tracking the position of an object moving around a playing area is provided, the system comprising at least three tracking devices configured to be arranged around the playing area, wherein each tracking device comprises: a linear distance measurement unit configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices to create a linear distance measurement set; and a pressure sensor configured to measure air pressure at the position of the tracking device.

[0066] This corresponds to a system suitable for use according to the method of the third aspect of the present application. Likewise, all the preferred features described above also apply to this system.

[0067] Preferably, the system further comprises a data processing device configured to calculate the relative height of each tracking device based on the air pressure measured at the location of each tracking device, and to create a device topology of at least three tracking devices based on the set of linear distance measurements and the estimated relative height of each tracking device. This may be operated as described above with respect to the third aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The present application will now be described with reference to the accompanying drawings, in which:

[0069] Figure 1 schematically illustrates the positioning of elements of a sports tracking system around a sports field during setup;

[0070] Figure 2 Schematically illustrates the structure of a tracking device of a motion tracking system;

[0071] Figure 3 schematically illustrates the structure of certain elements of a motion tracking system;

[0072] Figure 4 is a flow chart showing the setup of a motion tracking system;

[0073] Figure 5 is a flow chart illustrating the operation of a motion tracking system;

[0074] Figure 6 and Figure 7 schematically illustrates the creation of a tracking device topology for a motion tracking system; and

[0075] Figures 8 to 10 The determination of the arrangement of the tracking device topology relative to the sports field is schematically illustrated. DETAILED DESCRIPTION

[0076] Figure 1 Elements of a motion tracking system are shown during setup. The motion tracking system is being set up on a football field 10. As previously mentioned, the present technology can be applied to other sports fields or playing areas, and can be applied to scenarios outside of sports, such as tracking objects in a warehouse, at a concert, or in a studio. The tracking system includes an array of tracking devices 100. The tracking devices are arranged around the sports field 10, outside the field markings. For example, the tracking devices 100 can be fixed to a convenient infrastructure around the sports field, or supported on a fixed support positioned outside the field markings, such as supported on a tripod. In this embodiment, 12 tracking devices are used, but 3 or more tracking devices of any number are also possible. Typically, a large number of tracking devices improves the tracking capability of the system in the event of any failure or obstruction of the tracking device, and provides redundancy for the tracking device. The tracking devices 100 are relatively evenly distributed around the sports field, which also improves the tracking capability of the system.

[0077] Figure 2 The structure of the tracking device 100 is shown. The tracking device 100 includes an ultra-wideband (UWB) transceiver 110, which is used as a linear distance measurement unit. The UWB transceiver is preferably equipped with three spaced-apart antennas for transmitting and receiving UWB signals, and the three spaced-apart antennas are arranged in a triangle; however, as an alternative, the tracking device can be equipped with three separate UWB transceivers, which are also not arranged in a straight line. The tracking device also includes a communication module for communicating with the central computer 300, such as Figure 3As shown. The communication module can be any device that transmits data to the central computer 300, including Wi-Fi, a wired Ethernet port, or Bluetooth, etc. In some embodiments, a UWB transceiver can be used to transmit data to the central computer 300, in which case a dedicated communication module 120 is not required. The tracking device 100 also includes a GNSS receiver configured to obtain position measurements using GNSS, such as a GPS receiver. In some embodiments where the tracking is intended to optically track objects on the sports field 10, the tracking device may include a camera 140. Although tracking systems often use high-speed cameras, any camera may be used in this article. Finally, the tracking device includes a series of micro-electromechanical system (MEMS) sensors 150, including a pressure sensor 151, an accelerometer 152, a gyroscope 153, and a magnetometer 154. Each tracking device can be battery powered ( Figure 2 ), preferably using rechargeable batteries for portability. Alternatively, the tracking device may include a connector cable for being powered by an external power source such as a mains power supply.

[0078] Likewise Figure 1 As shown, the motion tracking system includes a plurality of mobile electronic devices, namely tags, positioned at a site 10. In the case where the tracking device is intended to track an object using a UWB transceiver 110, the tag 50 may include a corresponding UWB transceiver for communicating with the tracking device. Figure 2 Only two tags 50 are shown on the field, but it should be understood that more tags may be used (e.g., if each player wears a tag 50), or only one tag may be used (e.g., if the system is only intended to track the ball during play). It should also be noted that where tracking is optical, such as with a camera 140, the tracking system may not require a tag 50 to operate.

[0079] Figure 1 Also shown are three reference devices 200 that have been positioned on the playing field. In particular, a first reference device 200a has been positioned at the intersection of the midfield line with one of the sidelines, a second reference device 200b has been positioned at the intersection of the same sideline with one of the touchdown lines, and a third reference device 200c has been positioned at the intersection of the opposite sideline with the 22-meter line between the midfield line and the same touchdown line. In a preferred embodiment, the reference devices are configured to be aligned with the reference devices. Figure 2 The tracking device 100 shown and described is the same.

[0080] Figure 3 Shows something like Figure 1 Part of the motion tracking system shown. In particular, Figure 3 The central computer 300 ( Figure 1100) and the way in which the two tracking devices 100 communicate with each other. In this embodiment, each tracking device only includes a UWB transceiver 110, a communication module 120 and a MEMS sensor 150. It should be noted that although Figure 3 The interaction of two tracking devices 100 is shown, but since the reference device 200 is preferably constructed identically to the tracking device, the communications shown will similarly apply to the communications of the tracking device 100 with the reference device 200 .

[0081] like Figure 3 As shown, the UWB transceiver 110 of each tracking device 100 is configured to communicate with the UWB transceiver of each other tracking device 100, although in Figure 3 Only two tracking devices are shown in FIG. 1 . Such communication between the UWB transceiver 110 of each tracking device 100 allows the distance between the two tracking devices to be established, for example by using time of flight (TOF) or time difference of arrival (TDOA). The relative orientation of the tracking devices can also be determined by using phase difference of arrival (PDOA) or angle of arrival (AOA), as measured using three separate antennas on each UWB transceiver. The tracking devices also collect data by using their respective MEMS sensors 150. Data from the UWB transceiver and MEMS sensor of each tracking device 100 is transmitted to the central computer 300 via respective communication modules 120. The central computer 300 includes a controller 310 and a communication module 320. The communication module 320 receives UWB and MEMS sensor data from the tracking devices and transmits the UWB and MEMS sensor data to the controller 310. The controller is responsible for interpreting the data received from all tracking devices during calibration and operation of the system, which will now be described.

[0082] Figure 4 A method of setting up and calibrating a tracking system is shown. First, in step S100, tracking devices 100 are arranged around a tracking area. In this step, the tracking devices 100 should be positioned at the locations they are intended to occupy during operation of the tracking system. However, as will be described below, the system can be configured to take into account movement of the tracking devices 100 after calibration. Figure 1In the example of , the tracking devices are arranged around the sports field, each of which is outside the sports field. The tracking devices should be arranged so that each tracking device has a clear line of sight with at least two other tracking devices, preferably at least three other tracking devices, and more preferably at least four tracking devices. In the most preferred case, each tracking device 100 will have a clear line of sight with each other tracking device. Step S100 will depend on the specific area to be tracked. For example, on a sports field where the stands are very close, it may be necessary to position one or more tracking devices in or above the stands. Other tracking devices 100 can be positioned on a supporting structure such as a tripod that is intended to be positioned around the tracking area. As will be further explained below, it is preferred that three of the tracking devices 100 are arranged to define a large, substantially equilateral triangle, and this can be taken into account when positioning the tracking devices. As described above, it is also preferred that the tracking devices are relatively evenly positioned around the sports field, for example, at least two are positioned on each side of the sports field to ensure good tracking capabilities.

[0083] In step S110, a linear distance is calculated between each tracking device 100 by using their UWB transceivers 110. For example, each tracking device 100 may send a TOF signal to each other tracking device using their UWB transceivers 110. Based on this TOF data sent from the tracking device 100 to the computer 300 by using the communication module, the controller 310 may calculate the linear distance between each tracking device.

[0084] In step S120, the air pressure is measured at each tracking device at two minute intervals using their respective pressure sensors 151. It should be noted that although step S120 is shown as occurring after step S110, the two steps may occur at least partially simultaneously, or vice versa. The pressure measurements of each tracking device are then transmitted to the computer 300 using the communication module 120, 320.

[0085] The method shown uses only linear distance measurements and pressure measurements, but the method here may also include collecting GNSS position data by using the GNSS receiver 130 of each tracking device and sending the GNSS position data to the controller 310 .

[0086] In step S130, the controller 310 uses the received data to create a device topology reflecting the locations of the tracking devices 100 around the sports field 10. In this embodiment, the device topology is based on both linear distance measurements calculated from the UWB TOF data and the pressure data. Figure 6 and Figure 7 Illustrate the process of creating a device topology.

[0087] The first part of this step may include determining the relative altitude difference of the tracking devices 100 based on the measured pressure. This may include first comparing the pressure reading of each tracking device 100 to a first tracking device or multiple tracking devices that have been positioned at a known altitude. This may require the altitude of the device to be measured, or, for example, the tracking devices may be positioned on a tripod at a known altitude. The pressure reading at the first tracking device within the two minutes of the measurement may then be subtracted from the pressure readings at the other tracking devices within the same two minutes in order to eliminate natural variations in atmospheric pressure. The resulting difference in the measured pressure of each tracking device may then be converted to an altitude difference for the tracking devices.

[0088] Next, the controller 310 can begin building a device topology, and for this substantially two-dimensional arrangement of tracking devices, building the device topology can begin by selecting a starting set of three of the tracking devices 100. An ideal starting set of tracking devices 100 is a substantially equilateral large triangle. This can be identified from the linear distance measurements. In particular, a set of three tracking devices that have a large linear distance measurement between them and a low variance in linear distance between them would be preferred. Figure 6 A suitable starting set of tracking devices in this particular example is shown, with dashed lines showing distance measurements for the starting set. Here, two tracking devices are selected adjacent one sideline of the football field 10, at opposite ends of the sideline, while a third tracking device is selected adjacent the opposite sideline, flush with the midfield line.

[0089] By selecting these three tracking devices 100, one of the tracking devices can be designated as the origin P0, and the position of any one of the remaining devices P1 can be selected to define the x-axis. The position of the third device can be considered to be in the y direction from the tracking device designated as the origin. Then, the unit vector for x can be derived as follows:

[0090]

[0091] Then, a unit vector indicating the y direction but not in the y direction can be found as follows:

[0092]

[0093] According to the right-hand rule, and The cross product of will give the correct unit vector for the z direction, so:

[0094]

[0095] Therefore, the true unit vector for the y direction can be found as follows:

[0096]

[0097] Therefore, the three tracking devices are now located within the coordinate system.

[0098] With the first three tracking devices now within the coordinate system, additional tracking devices can now be added to the coordinate system. Figure 7 As shown, any one of the remaining tracking devices 100 may be selected and incorporated into the device topology. Figure 7 The linear distance measurements between the starting set of tracking devices 100 are shown in solid lines, and the linear distance measurements between each of these tracking devices in the starting set and the next tracking device to be added are shown in dashed lines. With the established coordinate system and three linear distance measurements from the starting set of tracking devices 100 already located in the coordinate system, the position of the next tracking device can be determined in the same way as follows: find the intersection of three circles centered at each of the starting set of tracking devices 100 and with a radius defined to measure the linear distance to the next tracking device.

[0099] This step may be repeated for subsequent tracking devices until all tracking devices have been located within the defined coordinate system. It should be understood that each additional tracking device 100 may be incorporated based solely on linear distance measurements from the starting set, or with any three tracking devices already located within the coordinate system, or with linear distance measurements from more than three tracking devices, to further determine position and help prevent error propagation.

[0100] Optionally, the method can repeat the above process for generating a device topology for each possible starting set of tracking devices. This will generate as many device topologies (referred to herein as preliminary device topologies) as the unique starting set of tracking devices. In order to resolve measurement errors in the starting set, each of these preliminary device topologies can now be compared. The position of each device in each preliminary device topology can be compared with the average position of the device determined from all other device topologies. If the position of any device in any preliminary device topology differs from the average position by, for example, more than 5cm, the preliminary device topology can be ignored, or the device position in the preliminary device topology can be ignored. Alternatively, the comparison can be used to identify which one or more linear distance measurement results lead to incorrectly calculated device positions and those ignored measurements. In this case, it may be necessary to update the preliminary device topology. Once each preliminary device topology is evaluated in this way, the device topology to be used in the rest of the method can be established, for example, by taking the average value of the device positions in the remaining preliminary device topologies. The process can also be performed as a random sampling consensus method, wherein the process iteratively repeats the step of estimating the device position based on the preliminary device topology, such as by taking the average value (e.g., median), and ignoring the information threshold amount associated with any outliers outside the estimated device position. This iterative process will gradually increase the accuracy of the estimate until all remaining data agree within a threshold amount.

[0101] Once the location of each of the tracking devices is established within the device topology, the orientation of each of these tracking devices can be set relative to each other. As described above, the relative orientation of the tracking devices can be determined using PDOA or AOA, as determined by measurements made using the three antennas of each UWB transceiver.

[0102] By using only linear distance measurements to calculate the position and orientation of the devices, their height can be optimized by incorporating pressure data. The calculated positions define a new topology that can be compared to the set of UWB measurements originally made. These topologies can be represented as two matrices of inter-device measurements. If the UWB measurements are accurate, the calculated positions of the devices will be accurate, and the two matrices will be the same. However, due to measurement noise and normal variability, the calculated positions will not be accurate. At this stage, a stochastic optimization algorithm can be used to incorporate the pressure sensor data to ensure the correct relative height difference between the anchors while optimizing the positions so that the calculated topology is consistent with both the original UWB measurements and the pressure sensor data. This can be achieved by minimizing an objective function.

[0103] It will be appreciated that the above examples are considered to be substantially two-dimensional. However, the techniques will apply similarly to three-dimensional arrangements of tracking devices. Instead of identifying a starting set of three tracking devices that defines an equilateral triangle, it would be necessary to define a starting set of four tracking devices that is a tetrahedron having edges of approximately the same length. The coordinate system is defined for the starting set of three in substantially the same manner as described above, with the position of the fourth device being determined as the intersection of three spheres centered at the initial three tracking devices and having a radius of the measured distance to the fourth tracking device. Thereafter, additional tracking devices may again be incorporated via the intersection of four or more spheres. This may be repeated for each starting set in the same manner as described above.

[0104] Once all tracking devices have been positioned within a coordinate system initially defined relative to the starting set of tracking devices, the device topology is known, indicating the relative position in space of each of the tracking devices 100. However, at this stage, the position of these devices relative to the area to be tracked, i.e. relative to the playing field 10, is unknown.

[0105] With the device topology created, in step S140, three reference devices 200 are located within the tracking area. Although step S140 is described as occurring after steps S100 to S130, this step may also be performed before or during any of the foregoing steps. As described above, the reference device may be constructed identically to the tracking device 100.

[0106] As described above, in this embodiment, the first reference device 200a is positioned at the intersection of the midfield line and one of the sidelines of the football field 10, the second reference device 200b is positioned at the intersection of the same sideline and one of the touchdown lines, and the third reference device 200c is positioned at the intersection of the opposite sideline and the 22-meter line between the midfield line and the same touchdown line where the second reference device is positioned. These reference devices may be positioned directly on the field, or may be positioned on a tripod, for example, at a known height above the field.

[0107] It should be noted that such positioning of the reference devices will allow the dimensions of the field to be measured. In particular, the distance between the first reference device and the second reference device will indicate the distance between the touchdown line and the midfield line. The vertical distance between the third reference device and the line connecting the first reference device and the second reference device will indicate the distance between the opposing sidelines. These distances can be determined using measurements directly between the reference devices, since these devices themselves have UWB transceivers, or can be determined using distance measurements between the tracking device 100 and the reference devices, or can be determined using some combination. It should also be understood that further combinations of reference devices can be used to determine more dimensions of the field, as desired. In this embodiment, it is assumed that the opposing halves of the field have the same size, but this can also be confirmed using additional reference devices 200.

[0108] In step S150, the linear distance between each tracking device 100 and each reference device 200 is calculated using its UWB transceiver 110. For example, each tracking device 100 may send a TOF signal to each reference device using their UWB transceiver 110. Based on this TOF data sent from the tracking device 100 to the computer 300 using the communication module, the controller 310 may calculate the linear distance between each tracking device 100 and each reference device 200.

[0109] It should also be noted that the method may also include pressure data obtained at the reference device 200 and the tracking device 100. If all devices are in place, the pressure data of the reference device may be obtained at the same time as the tracking device, i.e., in step S120, or the pressure data of all devices may be collected again after step S140. As described above, the pressure data may be used again in subsequent steps to determine the height difference between the reference device and the tracking device.

[0110] Finally, in step S160 , the method comprises determining the arrangement of the created device topology relative to the playing field based on the linear distance measurements and based on any pressure measurements acquired by the reference device. Figures 8 to 10 The process is shown.

[0111] Figure 8 A first reference device 200a is shown positioned relative to the tracking device 100 in the coordinate system. Figure 8Linear distance measurements between four of the tracking devices 100 and the reference device 200a are shown in dashed lines; however, it should be understood that linear distance measurements from all tracking devices 100 can be used if such measurements can be made. Based on these linear distance measurements, the controller can determine the position of each of the tracking devices relative to the intersection of the midfield line and the sideline of the football field. The reference point can be designated as the origin of the coordinate system; however, alternatively, the origin can be set arbitrarily relative to the reference point.

[0112] Knowing the relative position of the tracking device topology to a point on the field is not sufficient to fix the sports field in the coordinate system. For example, the sports field can be rotated around the fixed reference point in the coordinate system and still satisfy the measured distance between the tracking device 100 and the first reference device 200a. Therefore, at least a second reference device is required in order to fix the sports field in the coordinate system.

[0113] Fig. 9 10. A second reference device 200b is shown positioned relative to the tracking device 100 in the coordinate system. The figure now shows the measurements for the first reference device 200a in solid lines, indicating that point is now fixed in the coordinate system, and the linear distance measurements between four of the tracking devices 100 and the second reference device 200b in dashed lines. Additionally, linear distance measurements from all of the tracking devices 100 are preferably used, but these are not shown in the drawing for clarity. Based on these linear distance measurements, the controller 310 is able to establish the position of each of the tracking devices 100 relative to the intersection of the touchdown line and the sideline of the football field 10. It should also be noted that the controller is able to determine a reference direction within the coordinate system based on these measurements, i.e., the direction of the sideline of the football field.

[0114] In some embodiments, fixing two such reference points in the coordinate system may be sufficient to fix the football field 10 in the coordinate system. For example, it may be assumed that the plane of the tracking device is the same as the plane of the football field. However, in this embodiment, measurements of a third reference device are used to fix the football field 10 in the coordinate system.

[0115] Fig.10A third reference device 200c is shown positioned relative to the tracking device 100 in the coordinate system. The figure now shows the measurements of the first and second reference devices 200a, 200b in solid lines, indicating that these points are now fixed in the coordinate system, and the linear distance measurements between four of the tracking devices 100 and the third reference device 200c in dashed lines. In addition, it is preferred to use linear distance measurements from all tracking devices 100, but for the sake of clarity, these measurements are not shown in the drawings. Based on these linear distance measurements, the controller 310 is able to establish the position of each of the tracking devices 100 relative to the intersection of the 22-meter line and the sideline of the football field 10. It should also be noted that the controller is able to determine a second reference direction within the coordinate system based on these measurements, namely the direction of the midfield line, the touchdown line and the 22-meter line of the football field.

[0116] It should be noted that even if these three reference points are fixed within the coordinate system of the tracking device, the vertical direction is still unknown, that is, it may not be known on which side of the planar sports field the game will be played. Again, this can be solved by assumptions, for example, about the height of the tracking device relative to the height of the reference devices. However, the reference devices can be numbered sequentially, and the order of the reference devices on the field can be used to confirm the vertical direction. For example, in order to convey this information, it may be necessary to arrange the reference devices in a counterclockwise order as viewed from above the sports field.

[0117] With the tracking device topology established relative to the coordinate system and the playing field fixed within that coordinate system, the tracking system is now calibrated and able to track the motion of an object, such as tag 50, within its coordinate system.

[0118] It should also be noted that the reference device 200 can now be moved outside of the sports field 10 and used as an additional tracking device after calibration has been performed. In this case, the location of the reference device 200 (in its capacity as a tracking device) will need to be incorporated into the tracking device topology. This can be achieved by placing the reference device 200 in its desired position around the sports field 10 and then locating the reference device 200 in the same manner as above. Figure 7 Reference devices are added to the device topology in the same manner as described above. In particular, the linear distance measurement between any one of the existing tracking devices 100 and each reference device can be used to locate the reference device within the coordinate system in the same manner as finding the intersection of a circle centered at the existing tracking device 100 and whose radius is defined to measure the linear distance to the reference device to be used as the tracking device.

[0119] Although the above method is described as using only tracking devices to generate a device topology, and then using measurements of reference devices to fix the topology to the coordinate system of the sports field, the method can also build a combined device topology for all tracking devices and reference devices in a single process. That is, steps 110 to 130 can be performed while processing the same reference device as the tracking device, measuring the linear distance between the reference device and other tracking devices and / or reference devices to determine a topology including two groups of devices. In this case, once the reference devices are included in the device topology, the arrangement of the device topology relative to the application area can be determined because the positions of those reference devices make them aware of the reference points in the competition area. For example, if the reference devices form a starting set, the arrangement of the tracking devices relative to the competition area can be known because the tracking devices are included in the device topology. Then, at the end of the process, the reference devices can be removed from the device topology so that only tracking devices with a known arrangement relative to the competition area are left.

[0120] As mentioned above, the problem with this tracking system is that any movement of the tracking device will corrupt the tracking data. Figure 5 A method for solving this problem is shown.

[0121] Figure 5 The method begins with setting up and calibrating the motion tracking system. The method can follow the calibration steps just described, or can be used after any other calibration technique, including those described in the Background section above.

[0122] In step S200, the tracking system monitors and detects the movement of one of the tracking devices. Movement of the tracking device may be detected in a variety of ways.

[0123] The first way in which movement can be detected is based on distance measurements made between the tracking devices of the tracking system. That is, the system can be configured to periodically use the UWB transceiver 110 of each tracking device 100 to send a TOF signal to each other tracking device 100. Based on this TOF data sent from the tracking device 100 to the computer 300 using the communication module, the controller 310 can check the linear distance between each tracking device. Movement of one of the tracking devices can be identified from this data, that is, based on changes in the measured linear distance. Movement of one of the tracking devices relative to the other tracking devices is generally identifiable when the moving tracking device will see a change in the linear distance measurement to substantially all other tracking devices, and substantially all other tracking devices will see a change in the linear distance measurement to the moving tracking device, while the other tracking devices remain substantially the same.

[0124] An alternative way in which motion may be detected is to use measurements from one or more of the MEMS sensors, namely, pressure sensor 151 (for vertical motion), accelerometer 152, gyroscope 153, and magnetometer 154. Again, the controller may monitor data from these sensors to identify when the tracking device is moved.

[0125] Where movement is detected, in step S210 the linear distance between the moving tracking device and each other tracking device is calculated. This is performed in the same manner as step S110 described above.

[0126] In optional step S220, the air pressure of each tracking device is measured, again in a manner similar to step S 120. This step will allow the system to update to reflect any changes in the altitude of the moving tracking device 100.

[0127] Finally, in step S230, the position of the mobile tracking device within the device topology is updated based on the measured linear distance and any pressure measurements. This method is similar to the above method, in particular with reference to Figure 7 That is, the new position of the moving tracking device 100 may be determined in the same manner as finding the intersection of circles centered at each of the other tracking devices, and whose radius is defined as measuring the linear distance to the moving tracking device.

[0128] The present application may be further understood by reference to the following numbered clauses.

[0129] Item 1, a method of operating a tracking system for tracking the position of an object moving around a tracking area, the method comprising: arranging at least three tracking devices around the tracking area, wherein each tracking device includes a linear distance measurement unit, the linear distance measurement unit being configured to measure a linear distance to at least two other tracking devices of the at least three tracking devices; for each tracking device, using the linear distance measurement unit, calculating a linear distance between the tracking device and the at least two other tracking devices to create a linear distance measurement set; based on the linear distance measurement set, creating a device topology of the at least three tracking devices; positioning a reference device at at least a first position, wherein at least the first position has a known relationship with a first reference point in the tracking area; calculating a linear distance between each of the at least three of the tracking devices and the reference device at the first position to create a reference measurement set; and determining an arrangement of the device topology relative to the tracking area based on the reference measurement set.

[0130] Item 2, according to the method of Item 1, comprising: positioning a reference device at each of at least a first position and a second position, wherein at least the first position and the second position together have a known relationship with a first reference point in a tracking area and a second reference point or a first reference direction in the tracking area, and also comprising: calculating a linear distance between each of at least three of the tracking devices and the reference device at the second position to create a reference measurement set.

[0131] Clause 3, according to the method of clause 2, comprising: positioning a reference device at a third position so that the first position, the second position and the third position are not arranged in a straight line, the third position and the first position and / or the second position together have a known relationship with a second reference direction in the tracking area, and using a linear distance measurement unit, calculating the linear distance between each of at least three of the tracking devices and the reference device at the third position to create a reference measurement set, and wherein preferably, determining the arrangement of the device topology relative to the tracking area is also based on the order of the first position, the second position and the third position.

[0132] Clause 4. The method of clause 3, wherein the first location, the second location, and the third location define a plane that is substantially parallel to the playing field in the tracking area.

[0133] Clause 5, a method according to any of the preceding clauses, wherein the first position has a known positional relationship with a first reference point in the tracking area, wherein preferably the first position substantially coincides with the first reference point.

[0134] Clause 6, according to the method of clause 5 when dependent on at least clause 2, wherein the second position has a known positional relationship with a second reference point in the tracking area, wherein preferably the second position substantially coincides with the second reference point.

[0135] Clause 7, according to the method of clause 6 when dependent on at least clause 3, wherein the third position has a known positional relationship with a third reference point in the tracking area, wherein preferably the third position substantially coincides with the third reference point.

[0136] Clause 8. A method according to at least clause 2, wherein the first position and the second position have a known angular relationship to a first reference direction, wherein preferably the first position and the second position define a line that is substantially parallel to the first reference direction.

[0137] Clause 9. A method according to any of the preceding clauses, wherein the first reference point corresponds to a field marking on a sports field in the tracking area, wherein preferably the first reference point corresponds to an intersection of at least two field lines on the sports field.

[0138] Clause 10. A method according to at least clause 2, wherein the first reference direction corresponds to a direction of a field line on a sports field in the tracking area.

[0139] Clause 11, a method according to clause 2, wherein the first position is located at the intersection of at least two field lines on a sports field in the tracking area, and wherein the second position is located from the first position along one of the two field lines, wherein preferably the second position is located at the intersection of a third field line and one of the at least two field lines, so that at least one dimension of the sports field can be determined based on a reference measurement set.

[0140] Item 12, a method according to at least Item 2, wherein either: a first reference device is positioned at a first position and a second reference device is positioned at a second position; or: the first reference device is positioned at the first position and then, after calculating a linear distance between each of at least three of the tracking devices and the first reference device at the first position, the first reference device is positioned at the second position.

[0141] Clause 13, a method according to any of the preceding clauses, wherein the reference device or each reference device is an additional tracking device comprising a linear distance measurement unit configured to measure the linear distance to at least two of the at least three tracking devices, and the method further comprises: after creating the corresponding (one or more) reference measurement sets, arranging the reference device or each reference device around the tracking area, using one or more linear distance measurement units, calculating the linear distance between the additional tracking device or each additional tracking device and at least two of the at least three tracking devices, and updating the device topology to include the reference device or each reference device.

[0142] Clause 14, a method according to any of the preceding clauses, wherein one or more of the tracking device and / or the reference device includes a GNSS receiver configured to make GNSS position measurements of the device, and wherein determining the arrangement of the device topology relative to the tracking area is also based on the GNSS position measurements.

[0143] Clause 15, according to the method of any of the preceding clauses, further comprising: after creating the device topology, detecting the movement of one of the at least three tracking devices relative to other tracking devices of the at least three tracking devices, using a linear distance measurement unit, recalculating the linear distance between the moved tracking device and each of the at least two other tracking devices, and updating the device topology based on the recalculated linear distance between the moved tracking device and each of the at least two other tracking devices of the at least three tracking devices to take into account the movement of the moved tracking device.

[0144] Clause 16, according to the method of clause 15, comprising: for each tracking device, using a linear distance measurement unit, periodically recalculating the linear distance between the tracking device and at least two other tracking devices, and wherein detecting the movement of one of the at least three tracking devices is based on the change in the linear distance between the moving tracking device and the other at least two other tracking devices detected after the recalculation.

[0145] Clause 17, a method according to clause 15 or clause 16, wherein each tracking device further comprises one or more of an accelerometer, a gyroscope and a magnetometer, and wherein detecting movement of one of the at least three tracking devices relative to the other tracking devices is based on readings from the accelerometer, gyroscope and / or magnetometer.

[0146] Clause 18, a method according to any of the preceding clauses, wherein each tracking device further comprises a pressure sensor configured to measure the air pressure at the location of the tracking device, and the method further comprises: calculating the relative height of each tracking device based on the air pressure measured at the location of each tracking device, and wherein creating the device topology is also based on the calculated relative height of each tracking device.

[0147] Clause 19. The method according to clause 18, comprising: arranging at least four tracking devices around a tracking area, wherein each tracking device is arranged substantially in the same plane within a tolerance of 10 meters, preferably within a tolerance of 5 meters, more preferably within a tolerance of 2 meters, and most preferably within a tolerance of 1 meter, and wherein preferably one or more of the tracking devices are arranged at least 50 meters apart, preferably at least 70 meters apart, and more preferably at least 100 meters apart.

[0148] Clause 20. The method of any of the preceding clauses, wherein the linear distance measurement unit of each tracking device is further configured to measure the linear distance to one or more mobile electronic devices moving around the tracking area.

[0149] Clause 21. A method as in any preceding clause, wherein the linear distance measurement unit of each tracking device comprises an ultra-wideband (UWB) transmitter and / or receiver.

[0150] Clause 22, a method according to any of the preceding clauses, wherein a linear distance measurement unit of at least one tracking device comprises at least a first antenna and a second antenna for making linear distance measurements, and the method further comprises: calculating a relative orientation of the at least one tracking device using the linear distance measurements obtained using the first antenna and the second antenna.

[0151] Clause 23, a method according to any of the preceding clauses, wherein at least one tracking device includes a plurality of linear distance measurement units, and the method further comprises: calculating a linear distance between each of the plurality of linear distance measurement units on the at least one tracking device and at least one other tracking device, and calculating a relative orientation of the at least one tracking device based on a difference in the calculated linear distances.

[0152] Clause 24. A method as in any of the preceding clauses, wherein the one or more tracking devices include a camera for optically tracking the position of an object moving around a tracking area.

[0153] Clause 25. The method of any of the preceding clauses, wherein arranging at least three tracking devices around the tracking area comprises: fixedly positioning each tracking device around the tracking area.

[0154] Clause 26, a method according to any one of the preceding clauses, comprising: arranging at least four tracking devices, preferably at least six tracking devices, and more preferably at least ten tracking devices around a tracking area, wherein preferably each tracking device comprises a linear distance measurement unit, and the linear distance measurement unit is configured to measure the linear distance to at least three other tracking devices.

[0155] Clause 27, a method according to clause 26, wherein creating a device topology of at least four tracking devices based on the set of linear distance measurements includes: identifying a starting set of three tracking devices based on magnitudes of linear distance measurements in the set of linear distance measurements and differences between the linear distance measurements, defining a coordinate system using linear distance measurements between each of the starting set of tracking devices, and then locating a fourth tracking device in the coordinate system defined for the starting set of tracking devices based on linear distance measurements between the fourth tracking device and each of the tracking devices in the starting set of tracking devices.

[0156] Clause 28, a method of operating a tracking system for tracking the position of an object moving around a tracking area, the method comprising: at least three tracking devices are fixedly arranged around the tracking area, wherein each tracking device includes a linear distance measurement unit, the linear distance measurement unit is configured to measure the linear distance to at least two other tracking devices of the at least three tracking devices, wherein the at least three tracking devices have a known device topology; detecting the movement of one of the at least three tracking devices relative to the other tracking devices of the at least three tracking devices; using the linear distance measurement unit, calculating the linear distance between the moving tracking device and each of the at least two other tracking devices; based on the calculated linear distance between the moving tracking device and each of the at least two other tracking devices of the at least three tracking devices, updating the device topology to take into account the movement of the moving tracking device.

[0157] Clause 29. A method according to clause 28, wherein detecting the movement of one of at least three tracking devices comprises: for each tracking device, using a linear distance measurement unit, periodically calculating the linear distance between the tracking device and at least two other tracking devices, and detecting the movement of one of the at least three tracking devices based on a change in the linear distance between the moving tracking device and the at least two other tracking devices detected after the calculation.

[0158] Clause 30, a method according to clause 28 or clause 29, wherein each tracking device further comprises one or more of an accelerometer, a gyroscope, and a magnetometer, and wherein detecting movement of one of the at least three tracking devices relative to the other tracking devices is based on readings from the accelerometer, gyroscope, and / or magnetometer.

[0159] Clause 31. A method according to any one of clauses 28 to 30, wherein each tracking device further comprises a pressure sensor configured to measure the air pressure at the location of the tracking device, and the method further comprises: calculating a relative height of each tracking device based on the air pressure measured at the location of each tracking device, and wherein updating the device topology is also based on the calculated relative height of each tracking device.

[0160] Item 32, a method of operating a tracking system for tracking the position of an object moving around a tracking area, the method comprising: arranging at least three tracking devices around the tracking area, wherein each tracking device includes a linear distance measurement unit and a pressure sensor, the linear distance measurement unit being configured to measure the linear distance to at least two other tracking devices among the at least three tracking devices, and the pressure sensor being configured to measure the air pressure at the position of the tracking device; for each tracking device, using the linear distance measurement unit, calculating the linear distance between the tracking device and the at least two other tracking devices to create a linear distance measurement set; calculating the relative height of each tracking device based on the air pressure measured at the position of each tracking device; and creating a device topology of the at least three tracking devices based on the linear distance measurement set and the calculated relative height of each tracking device.

[0161] Item 33, a tracking system for tracking the position of an object moving around a tracking area, the system comprising: at least three tracking devices configured to be arranged around the tracking area, wherein each tracking device includes a linear distance measurement unit, the linear distance measurement unit configured to measure the linear distance to at least two other tracking devices of the at least three tracking devices to create a linear distance measurement set; and a data processing device configured to create a device topology of the at least three tracking devices based on the linear distance measurement set; at least one reference device, the at least one reference device configured to be positioned at at least a first position, wherein at least the first position has a known relationship with a first reference point in the tracking area; wherein the data processing device is further configured to receive a reference measurement set, the reference measurement set including linear distance measurements between each of at least three of the tracking devices and the reference device at the first position, and is further configured to determine the arrangement of the device topology relative to the tracking area based on the reference measurement set.

[0162] Item 34, a tracking system for tracking the position of an object moving around a tracking area, the system comprising: at least three tracking devices configured to be arranged around the tracking area in a known device topology, wherein each tracking device includes a linear distance measurement unit, the linear distance measurement unit configured to measure linear distances to at least two other tracking devices of the at least three tracking devices to create a set of linear distance measurements; and a data processing device configured to detect movement of one of the at least three tracking devices relative to other tracking devices of the at least three tracking devices, and to update the device topology based on the set of linear distance measurements to take into account the movement of the moving tracking device.

[0163] Item 35, a tracking system for tracking the position of an object moving around a tracking area, the system comprising: at least three tracking devices configured to be arranged around the tracking area, wherein each tracking device includes a linear distance measurement unit and a pressure sensor, the linear distance measurement unit being configured to measure the linear distance to at least two other tracking devices of the at least three tracking devices to create a linear distance measurement set, and the pressure sensor being configured to measure the air pressure at the position of the tracking device.

[0164] Clause 36, a system according to clause 35, further comprising: a data processing device configured to calculate a relative height of each tracking device based on the air pressure measured at the location of each tracking device, and to create a device topology of at least three tracking devices based on the set of linear distance measurements and the estimated relative height of each tracking device.

Claims

1. A method of operating a motion tracking system for tracking the position of an object moving around a playing area, the method comprising: Arranging at least three tracking devices around the playing area, wherein each tracking device comprises a linear distance measurement unit; positioning a reference device at at least a first location, wherein the reference device comprises a linear distance measurement unit, and wherein at least the first location has a known relationship to a first reference point in the playing area; wherein the linear distance measurement unit is configured to allow measurement of a linear distance between each tracking device or reference device and at least three other tracking devices and / or reference devices; for each tracking device and reference device, using the linear distance measurement unit to calculate a linear distance between the tracking device or the reference device and at least three other tracking devices and / or reference devices to create a set of linear distance measurements; creating a device topology for the at least three tracking devices based on the set of linear distance measurements; and An arrangement of the device topology relative to the playing area is determined based on a linear distance measurement to at least the first location and a known relationship of at least the first location to the first reference point.

2. The method according to claim 1, comprising: A reference device is positioned at each of at least the first position and a second position, wherein at least the first position and the second position together have a known relationship to the first reference point in the playing area and a second reference point or a first reference direction in the playing area, and wherein the arrangement of the device topology relative to the playing area is determined based on linear distance measurements to the first position and the second position and the known relationship of the first position and the second position to the first reference point and the second reference point or the first reference direction.

3. The method according to claim 2, comprising: A reference device is positioned at each of the first position, the second position and the third position such that the first position, the second position and the third position are not arranged along a straight line, the third position and the first position and / or the second position together have a known relationship to a second reference direction in the playing area, and wherein the arrangement of the device topology relative to the playing area is determined based on a linear distance measurement to the third position and the known relationship of the third position together with the first position and / or the second position to the second reference direction, and wherein, preferably, the arrangement of the device topology relative to the playing area is also determined based on the order of the first position, the second position and the third position.

4. The method according to claim 3, wherein: The first position, the second position, and the third position define a plane that is substantially parallel to a playing surface in the playing area.

5. A method according to any one of the preceding claims, wherein: The first position has a known positional relationship with the first reference point in the playing area, wherein, preferably, the first position substantially coincides with the first reference point.

6. A method according to claim 5 when dependent on at least claim 2, wherein: The second position has a known positional relationship with the second reference point in the playing area, wherein, preferably, the second position substantially coincides with the second reference point.

7. The method according to claim 6 when dependent on at least claim 3, wherein: The third position has a known positional relationship with a third reference point in the playing area, wherein, preferably, the third position substantially coincides with the third reference point.

8. A method according to claim 2 or any preceding claim when dependent on claim 2, wherein: The first position and the second position have a known angular relationship to the first reference direction, wherein preferably the first position and the second position define a line that is substantially parallel to the first reference direction.

9. A method according to any one of the preceding claims, wherein: The first reference point corresponds to a field marking on the playing field in the playing area, wherein, preferably, the first reference point corresponds to an intersection of at least two field lines on the playing field.

10. A method according to claim 2 or any preceding claim when dependent on claim 2, wherein: The first reference direction corresponds to the direction of a field line on a sports field in the playing area.

11. A method according to claim 2 or any preceding claim when dependent on claim 2, wherein: The first position is located at the intersection of at least two field lines on a sports field in the playing area, and wherein the second position is positioned along one of the two field lines from the first position, wherein, preferably, the second position is located at the intersection of a third field line and one of the at least two field lines, so that at least one dimension of the sports field can be determined based on linear distance measurements to the first position and the second position.

12. A method according to claim 2 or any preceding claim when dependent on claim 2, wherein: Either a first reference device is positioned at the first position and a second reference device is positioned at the second position; or a first reference device is positioned at the first position and then, after calculating a linear distance between each of at least three of the tracking devices and the first reference device at the first position, the first reference device is positioned at the second position.

13. A method according to any one of the preceding claims, wherein: The reference device or each reference device is an additional tracking device, and the method further comprises: arranging the corresponding reference device or each corresponding reference device around the playing area after obtaining a linear distance measurement to the corresponding at least first position; calculating the linear distance between the additional tracking device or each additional tracking device and at least three of the at least three tracking devices using the linear distance measurement unit; and updating the device topology to include the additional tracking device or each additional tracking device.

14. A method according to any one of the preceding claims, wherein: One or more of the tracking device and / or the reference device comprises a GNSS receiver configured to make GNSS position measurements of the device, and wherein determining the arrangement of the device topology relative to the competition area is further based on the GNSS position measurements.

15. The method according to any one of the preceding claims, further comprising: After creating the device topology, detecting movement of one of the at least three tracking devices relative to other tracking devices of the at least three tracking devices; recalculating a linear distance between the mobile tracking device and each of at least two other tracking devices using the linear distance measurement unit; and updating the device topology based on the recalculated linear distance between the mobile tracking device and each of at least two other tracking devices among the at least three tracking devices to take into account the movement of the mobile tracking device.

16. The method according to claim 15, comprising: For each tracking device, a linear distance between the tracking device and at least two other tracking devices is periodically recalculated using the linear distance measurement unit, and wherein movement of one of the at least three tracking devices is detected based on a change in the linear distance between the moving tracking device and the at least two other tracking devices detected after the recalculation.

17. The method according to claim 15 or 16, wherein: Each tracking device further comprises one or more of an accelerometer, a gyroscope and a magnetometer, and wherein detecting movement of one of the at least three tracking devices relative to the other tracking devices is based on readings from the accelerometer, the gyroscope and / or the magnetometer.

18. A method according to any one of the preceding claims, wherein: Each tracking device further comprises a pressure sensor configured to measure air pressure at the location of the tracking device, and the method further comprises calculating a relative height of each tracking device based on the measured air pressure at the location of each tracking device, and wherein creating the device topology is also based on the calculated relative height of each tracking device.

19. The method according to claim 18, comprising: At least four tracking devices are arranged around the playing area, wherein each tracking device is arranged in substantially the same plane within a tolerance of 10 meters, preferably within a tolerance of 5 meters, more preferably within a tolerance of 2 meters, most preferably within a tolerance of 1 meter, and wherein, preferably, one or more of the tracking devices are arranged at least 50 meters apart, preferably at least 70 meters apart, more preferably at least 100 meters apart.

20. A method according to any one of the preceding claims, wherein: The linear distance measurement unit of each tracking device is further configured to allow measurement of a linear distance between each tracking device and one or more mobile electronic devices moving around the playing area.

21. A method according to any one of the preceding claims, wherein: Each linear distance measurement unit includes an ultra-wideband (UWB) transmitter and / or receiver.

22. A method according to any one of the preceding claims, wherein: The linear distance measurement unit of at least one tracking device comprises at least a first antenna and a second antenna for performing the linear distance measurements, and the method further comprises calculating a relative orientation of the at least one tracking device using the linear distance measurements obtained using the first antenna and the second antenna.

23. A method according to any one of the preceding claims, wherein: At least one tracking device includes a plurality of linear distance measurement units, and the method further includes calculating a linear distance between each of the plurality of linear distance measurement units on the at least one tracking device and at least one other tracking device, and calculating a relative orientation of the at least one tracking device based on a difference in the calculated linear distances.

24. A method according to any one of the preceding claims, wherein: The one or more tracking devices include a camera for optically tracking the position of objects moving around the playing area.

25. A method according to any one of the preceding claims, wherein: Arranging at least three tracking devices around the playing area includes fixedly positioning each tracking device around the playing area.

26. A method according to any one of the preceding claims, comprising: At least four tracking devices, preferably at least six tracking devices, more preferably at least ten tracking devices, are arranged around the playing area, wherein preferably each tracking device comprises a linear distance measurement unit configured to allow measurement of linear distances to at least three other tracking devices.

27. The method according to claim 26, wherein: Creating a device topology of the at least four tracking devices based on the set of linear distance measurements includes: identifying a starting set of three tracking devices and / or reference devices based on the magnitudes of the linear distance measurements in the set of linear distance measurements and the differences between the linear distance measurements; defining a coordinate system using the linear distance measurements between each of the starting set of tracking devices and / or reference devices; and then, positioning the fourth tracking device or the reference device in the coordinate system defined for the starting set of tracking devices and / or reference devices based on the linear distance measurements between the fourth tracking device or the reference device and each of the tracking devices and / or reference devices in the starting set of tracking devices and / or reference devices.

28. The method according to claim 26 or 27, wherein: Creating the device topology of the at least four tracking devices includes: creating a preliminary device topology using each of a plurality of different starting sets of at least three tracking devices and / or reference devices, preferably each possible starting set of at least three tracking devices and / or reference devices; and creating the device topology using a plurality of the preliminary device topologies, preferably by taking an average of the preliminary device topologies.

29. The method according to claim 28, comprising: comparing the preliminary device topologies created from each starting set; ignoring one or more preliminary device topologies, locations of one or more devices within one or more preliminary device topologies, or one or more linear distance measurements based on a result of the comparing; And, creating the device topology using a plurality of remaining preliminary device topologies.

30. A method of operating a motion tracking system for tracking the position of an object moving around a playing area, the method comprising: stationarily arranging at least three tracking devices around the playing area, wherein each tracking device comprises a linear distance measurement unit configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices, wherein the at least three tracking devices have a known device topology; detecting movement of one of the at least three tracking devices relative to other tracking devices of the at least three tracking devices; using the linear distance measurement unit to calculate a linear distance between the moving tracking device and each of at least two other tracking devices; The device topology is updated to account for the movement of the mobile tracking device based on the calculated linear distance between the mobile tracking device and each of at least two other tracking devices among the at least three tracking devices.

31. The method according to claim 30, wherein: Detecting the movement of one of the at least three tracking devices includes: for each tracking device, using the linear distance measurement unit, periodically calculating the linear distance between the tracking device and at least two other tracking devices; and detecting the movement of one of the at least three tracking devices based on a change in the linear distance between the moving tracking device and the at least two other tracking devices detected after the calculation.

32. The method according to claim 30 or 31, wherein: Each tracking device further comprises one or more of an accelerometer, a gyroscope and a magnetometer, and wherein detecting movement of one of the at least three tracking devices relative to the other tracking devices is based on readings from the accelerometer, the gyroscope and / or the magnetometer.

33. The method according to any one of claims 30 to 32, wherein: Each tracking device further comprises a pressure sensor configured to measure air pressure at the location of the tracking device, and the method further comprises calculating a relative height of each tracking device based on the measured air pressure at the location of each tracking device, and wherein updating the device topology is also based on the calculated relative height of each tracking device.

34. A method of operating a motion tracking system for tracking the position of an object moving around a playing area, the method comprising: Arranging at least three tracking devices around the playing area, wherein each tracking device comprises: a linear distance measurement unit configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices; and a pressure sensor configured to measure air pressure at the location of the tracking device; for each tracking device, calculating a linear distance between the tracking device and at least two other tracking devices using the linear distance measurement unit to create a set of linear distance measurements; calculating a relative altitude of each tracking device based on the air pressure measured at the location of each tracking device; and A device topology of the at least three tracking devices is created based on the set of linear distance measurements and the calculated relative height of each tracking device.

35. A motion tracking system for tracking the position of an object moving around a playing area, the system comprising: at least three tracking devices configured to be arranged around the playing area, wherein each tracking device includes a linear distance measurement unit; A reference device, wherein the reference device comprises a linear distance measurement unit; wherein the linear distance measurement unit is configured to allow measurement of the linear distance between each tracking device or reference device and at least three other tracking devices and / or reference devices; and a data processing device configured to create a device topology of the at least three tracking devices based on a set of linear distance measurements, the set of linear distance measurements comprising linear distance measurements between the tracking device or the reference device and at least three other tracking devices and / or reference devices calculated for each tracking device and reference device using the linear distance measurement unit; Wherein, the data processing device is further configured to receive a linear distance measurement of the reference device positioned at at least a first position, wherein at least the first position has a known relationship with a first reference point in the competition area, and the data processing device is further configured to determine the arrangement of the device topology relative to the competition area based on the linear distance measurement to at least the first position and the known relationship between at least the first position and the first reference point.

36. A motion tracking system for tracking the position of an object moving around a playing area, the system comprising: at least three tracking devices configured to be arranged around a playing area having a known device topology, wherein each tracking device comprises a linear distance measurement unit configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices to create a set of linear distance measurements; and Data processing means are configured to detect movement of one of the at least three tracking devices relative to other tracking devices of the at least three tracking devices and to update the device topology based on the set of linear distance measurements to account for the movement of the mobile tracking device.

37. A motion tracking system for tracking the position of an object moving around a playing area, the system comprising: At least three tracking devices are configured to be arranged around the playing area, wherein each tracking device comprises: a linear distance measurement unit configured to allow measurement of a linear distance between each of the at least three tracking devices and at least two other tracking devices to create a set of linear distance measurements; and a pressure sensor configured to measure air pressure at the location of the tracking device.

38. The system of claim 37, further comprising: A data processing device is configured to calculate a relative height of each tracking device based on the air pressure measured at the location of each tracking device, and to create a device topology of the at least three tracking devices based on the set of linear distance measurements and the estimated relative height of each tracking device.

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