Estimation or verification of distance of a target with angle of arrival or angle of departure data

Abstract

A method comprising: wirelessly receiving, at a first device, at least one data packet from each second device of a plurality of second devices arranged at predetermined locations of a target; detecting an angle of arrival of each at least one data packet wirelessly received of at least a pair of second devices; calculating at least one angle difference between the angles of arrival associated with the pair of second devices, or between the angles of arrival associated with each of the pair of second devices and a predetermined direction; and determining whether the target is at a predetermined distance range from the first device by estimating the distance based on the at least one angle difference, and a predetermined distance between the predetermined locations; or checking whether each of the at least one angle difference is within a predetermined angle range for the predetermined locations of the pair of second devices. Also, a method for making such determination based on angles of departure.

Claims

1. A method comprising: (a) wirelessly receiving, at a computing device, at least one data packet from a first motion tracking device located on a target and at least one data packet from a second motion tracking device located on the target; (b) detecting, at the computing device, a first angle of arrival or a first angle of departure of the at least one data packet wirelessly received from the first motion tracking device and a second angle of arrival or a second angle of departure of the at least one data packet wirelessly received from the second motion tracking device; (c) calculating, at the computing device, at least one angle difference based at least on (i) the first angle of arrival and the second angle of arrival or (ii) the first angle of departure and the second angle of departure; (d) determining, at the computing device, whether the target is within a threshold distance from the computing device based at least in part on the at least one angle difference and locations of the first motion tracking device and the second motion tracking device; and (e) outputting an indication of whether the target is within the threshold distance to a user of the computing device.

2. The method of claim 1, wherein the first motion tracking device is located at a first location on the target, and wherein the second motion tracking device is located at a second location on the target.

3. The method of claim 2, further comprising calculating the distance separating the first motion tracking device and the second motion tracking device based on the first location and the second location.

4. The method of claim 1, further comprising calculating a distance between the computing device and the target based on the at least one angle difference and the distance separating the first motion tracking device and the second motion tracking device.

5. The method of claim 1, wherein the method comprises calibrating the computing device for a measurement of the target when the target is within the threshold distance.

6. The method of claim 5, wherein determining whether the target is within the threshold distance comprises: estimating a distance of the target from the computing device based on: the at least one angle difference, and a distance between a location of the first motion tracking device and a location of the second motion tracking device; or checking whether each of the at least one angle difference is within a predetermined angle range for the locations of the first motion tracking device and the location of the second motion tracking device.

7. The method of claim 1, wherein the method does not comprises calibrating the computing device for a measurement of the target prior to the determining of step (d).

8. The method of claim 1, wherein calculating the at least one angle difference comprises: calculating a first angle difference between the first angle of arrival of the first motion tracking device and a fixed direction, and a second angle difference between the second angle of arrival of the second motion tracking device and the fixed direction.

9. The method of claim 8, wherein determining whether the target is within the threshold distance comprises estimating a distance between the target and the computing device based on the first and second angle differences, the fixed direction, and a distance between a location of the first motion tracking device and a location of the second motion tracking device.

10. The method of claim 1, wherein the step of determining whether the target is within the threshold distance from the computing device is made further when the at least one angle difference is less than a maximum angle difference threshold.

11. The method of claim 1, further comprising estimating, at the computing device, the distance of the target from the computing device based on received signal strength indicators associated with one or more packets received from the computing device at the first motion tracking device and the second motion tracking device.

12. The method of claim 1, further comprising repeating the steps of (b)-(e) when the at least one angle difference is greater than a minimum angle difference threshold.

13. The method of claim 1, wherein the computing device and the first motion tracking device and the second motion tracking device form at least a part of a motion tracking system.

14. The method of claim 13, wherein the first motion tracking device and the second motion tracking device each comprises an inertial measurement unit.

15. The method of claim 14, further comprising processing, at the computing device, wirelessly received measurements of the inertial measurement unit of each of the first motion tracking device and the second motion tracking device to provide a motion tracking sequence of the target when the computing device determines that the target is within the predetermined distance range from the computing device.

16. The method of claim 14, further comprising halting, at the computing device, a motion tracking process when the computing device determines that the target is not within the threshold distance from the computing device.

17. The method of claim 16, wherein halting the motion tracking process further comprises: indicating how to move the target to bring the target within the threshold distance.

18. The method of claim 1, further comprising processing, at the computing device, one or more images of the target taken by an optical sensor; and at least one of: validating, based on the one or more processed images, that the first motion tracking device and the second motion racking device are arranged at a first location and a second locations of the target.

19. The method of claim 1, wherein the at least one angle difference is calculated based on (i) the first angle of arrival and the second angle of arrival.

20. The method of claim 1, wherein the at least one angle difference is calculated based on (ii) the first angle of departure and the second angle of departure.

21. The method of claim 1, wherein the at least one angle difference is calculated based on both (i) the first angle of arrival and the second angle of arrival and (ii) the first angle of departure and the second angle of departure.

22. A computing device comprising at least one processor, the at least one processor operative to: (a) wirelessly receive at least one data packet from a first motion tracking device located on a target and at least one data packet from a second motion tracking device located on the target; (b) detect a first angle of arrival or a first angle of departure of the at least one data packet wirelessly received from the first motion tracking device and a second angle of arrival or a second angle of departure of the at least one data packet wirelessly received from the second motion tracking device; (c) calculate at least one angle difference based at least on (i) the first angle of arrival and the second angle of arrival (ii) or the first angle of departure and the second angle of departure; (d) determine whether the target is within a threshold distance from the computing device based on the at least one angle difference and locations of the first motion tracking device and the second motion tracking device; and (e) output an indication of whether the target is within the threshold distance to a user of the computing device.

23. A motion tracking system comprising: a computing device operably coupled to a first motion tracking device and a second motion tracking device, wherein the computing device is operative to: (a) wirelessly receive at least one data packet from the first motion tracking device located on a target and at least one data packet from the second motion tracking device located on the target; (b) detect a first angle of arrival or a first angle of departure of the at least one data packet wirelessly received from the first motion tracking device and a second angle of arrival or a second angle of departure of the at least one data packet wirelessly received from the second motion tracking device; (c) calculate at least one angle difference based at least on (i) the first angle of arrival and the second angle of arrival (ii) or the first angle of departure and the second angle of departure; (d) determine whether the target is within a threshold distance from the computing device based on the at least one angle difference and locations of the first motion tracking device and the second motion tracking device; and (e) output an indication of whether the target is within the threshold distance to a user of the computing device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) To complete the description and in order to provide for a better understanding of the disclosure, a set of drawings is provided. Said drawings form an integral part of the description and illustrate embodiments of the disclosure, which should not be interpreted as restricting the scope of the disclosure, but just as examples of how the disclosure can be carried out. The drawings comprise the following figures:

(2) FIG. 1 shows a system in accordance with embodiments.

(3) FIGS. 2A-2C show several ways of determining whether a target is within a certain range with methods in accordance with embodiments.

(4) FIG. 3 shows how methods in accordance with some embodiments are capable of making the determination of the disclosure.

(5) FIGS. 4, 5A-5B and 6 show several ways of estimating distance of a target in accordance with embodiments.

(6) FIG. 7 illustrates example steps of a method for estimating the distance of a target in accordance with embodiments described herein.

DETAILED DESCRIPTION

(7) FIG. 1 shows a system 5 in accordance with embodiments, for example a motion tracking system. The system 5 includes a first device 10, and a plurality of second devices 20a-20n which may be identical or different; the plurality of second devices 20a-20n may include two second devices 20a, 20b, or more. When the system 5 is, for example, a motion tracking system, the first device 10 may be a computing device like e.g. a tablet, a mobile phone, a personal computer, etc., and the second devices 20a-20n be motion trackers.

(8) The first and second devices 10, 20a-20n each includes at least one processor 11, at least one memory 12, a wireless communications module 13 for radiofrequency signal transmission and reception; optionally, the first device 10 and/or the second devices 20a-20n also include an inertial measurement unit 15, IMU. The inertial measurement units 15 include inertial sensors, for example, a gyroscope 16 and an accelerometer 17.

(9) The wireless communications modules 13 of the first and second devices 10, 20a-20n each include one or more antennas 14 (one shown with dashed lines for illustrative purposes) for radiating and capturing electromagnetic waves.

(10) The at least one memory 12 of the first and second devices 10, 20a-20n may have instructions and/or a computer program stored therein that, upon execution by the at least one processor 11, enable the respective device 10, 20a-20n to perform computations such as determination of the angle of arrival or the angle of departure of received electromagnetic waves (although the respective wireless communications module 13 might also make such determination), and determine whether a target is within a predetermined distance range from a device.

(11) Although not illustrated, in some embodiments, the first device 10 and/or the second devices 20a-20n include an attaching device for attachment to a target, for instance to body members of a person; the attaching device might be any known in the art, e.g. straps, Velcro, etc.

(12) Further, the first device 10 and/or the second devices 20a-20n might additionally include user presenting means (e.g. a screen, loudspeakers, etc.) and/or user input means (e.g. a touchscreen, a keyboard, etc.). For example, the first device 10 might present to a user how to arrange the second devices 20a-20n on the target (which may the user too), and/or which exercises shall be performed by the user during a physical rehabilitation procedure assisted by an automated motion tracking system; the first device 10 might require manual input by the user of dimensions thereof for the first device 10 to calculate the predetermined distance that pairs of second devices 20a-20n might be apart.

(13) FIGS. 2A-2C show several ways of determining whether a target, in this case a person 30, is within a certain range from a remote first device 10 with methods in accordance with embodiments. For the sake of the following explanation only, a non-limiting set of Cartesian coordinates has been represented for better understanding of what is shown in the Figures. It will be noted that a different set of Cartesian coordinates could be represented as well.

(14) In FIG. 2A, the person 30 is seen from above. The person 30 is facing towards a first device 10, and has at least two second devices 20a, 20b arranged such that they are apart according to the Y axis illustrated (which is contained in a horizontal plane defined by the X and Y axes illustrated) by a distance or gap d.sub.ab. By way of example, one second device 20a is arranged on the chest of the person 30 and the other second device 20b is arranged on the left upper arm of the person 30.

(15) Dashed lines have been represented showing segments between each second device 20a, 20b and the first device 10. The first device 10 is capable of determining whether the person 30 is within a certain range from the first device 10 by digitally processing either measured angles of arrival or measured angles of departure of wireless communications received from the second devices 20a, 20b.

(16) FIG. 2B shows another example in which the person 30 is seen from the side and the second devices 20a, 20b are apart by a distance or gap d.sub.ab along the Z axis illustrated; the second devices 20a, 20b are arranged on the right upper and lower arm. The first device 10 is capable of making the aforesaid determination like in the example of FIG. 2A.

(17) FIG. 2C shows another example in which the person 30 is seen from the front and several second devices 20a, 20b, 20c are arranged on different body members. One second device 20a is on the chest, another second device 20b is on the right upper arm, and the last second device 20c is on the right lower arm. The distances or gaps between each pair of second devices 20a-20c is along different axes in each case: a first pair of devices 20a, 20b are apart along the Y axis illustrated (like in FIG. 2A), a second pair of devices 20b, 20c are apart along the Z axis illustrated (like in FIG. 2B), and a third pair of second devices 20a, 20c are apart along a composition of the Y and Z axes illustrated. In this example, the third pair of second devices 20a, 20c is explained, thus the distance or gap d.sub.ab between said second devices 20a, 20c has been represented.

(18) The first device 10 may likewise determine whether the person 30 is within a certain range from the first device 10 based on the angles of arrival or angles of departure associated with the wireless communications transmitted by the respective second devices 20a, 20c to the first device 10.

(19) If the person 30 were to be sideways relative to the first device 10, for example when the front of the person 30 forms an angle between e.g. 70° and 110° with respect to a front of the first device 10, the angles obtained by the first device 10 for the first pair or the third pair of second devices 20a-20c would be substantially small, and the distance or gap between each pair of second devices 20a-20c would not be representative of the determination to be made. In that case, the first device 10 may determine to use the RSSI values measured by one, some or all second devices 20a-20c, or resort to perform the angle-based determination with the second pair of second devices 20a-20c, which by being apart according to the Z axis do not alter the determination even if the person 30 is sideways.

(20) In all cases of FIGS. 2A-2C, the first device 10 has data indicative of the gaps (d.sub.ab, dac) for each pair of second devices 20a-20c that is to be considered. This means that the first device 10 associates: a certain gap with two second devices arranged on the upper arm and lower arm of a same arm, a certain gap with two second devices arranged on the chest and the upper arm, and so on.

(21) Although in the above figures the second devices 20a-20c have been shown arranged on the person 30 on particular body members, namely the chest and upper and lower arms, it will be noted that any other body members could have a second device 20a-20c arranged thereon without departing from the scope of the present disclosure, for example but without limitation, thighs, shins, shanks, feet, pelvis, neck, forehead, etc.

(22) It will also be apparent that the target does not necessarily have to be a person 30. By way of example, the target may be a robot, a drone, a remote controller for a computing apparatus like e.g. a computer or a video game console, a headset such as a virtual reality headset, one or more beacon devices that provide connectivity, data or orientation information, etc. Concerning the latter, the target can comprise a system of devices that usually have a fixed location; these may take benefit (or further benefit) from the disclosed methods and devices by not only determining whether they are at a predetermined distance from another device but also whether they have been moved (by assessing the evolution of the angles of arrival or angles of departure over time).

(23) FIG. 3 shows how methods in accordance with some embodiments are capable of making the determination of the disclosure.

(24) A first device 10 is apart from a target (not shown) that has at least a pair of second devices at predetermined locations thereof. Two antennas 14 of the antenna array of the first device 10 have been shown for clarity reasons. For the sake of the explanation, a second device 20a is at a predetermined location of the target whereas a plurality of predetermined locations is shown associated with the other second device 20b′, 20b″, 20b′″.

(25) Depending on the location of the second devices relative to the first device 10, the angle of arrival of wireless communications received at the first device 10 will be different. The angle for one of the second devices 20a is referenced as A, whereas two different angles B′ and B″ are shown for the other of the second devices 20b′, 20b″, 20b″ depending on their predetermined locations (it is noted that the device 20b′ and the device 20b″ are at a same direction Db′ relative to the first device 10 but at different distances). In this example, the reference for detecting the angles of arrival A, B′, B″ is parallel to one of the edges of the first device 10, but any other reference could be used instead because the angle difference that will exist between the different angles will be maintained regardless of the reference. The angle difference in this example is either B″ minus A, or B′ minus A.

(26) A predetermined distance or gap d.sub.ab is either provided beforehand (already registered data or manually introduced by e.g. a user) in relation to the predetermined locations of the pair of second devices under consideration, or calculated with e.g. an optical sensor and at least one processor that processes image(s) of the second devices at the locations. By way of example, if the pair of second devices were to be the second devices 20a, 20b″, which are at directions Da, Db′ from the first device 10, the angle difference between the two would be B′ minus A, the predetermined distance or gap would be d.sub.ab, and the distance to the target would be d.sub.t. With the angle difference and the gap d.sub.ab, the distance d.sub.t can be computed by means of trigonometrical relationships.

(27) In some occasions, minimum and maximum predetermined distances or gaps are considered rather than just a single predetermined distance or gap d.sub.ab. Said values, which are not represented but could be named e.g. d.sub.ab,MIN and d.sub.ab,MAX, result in the provision of two different triangles, each with one of the two gaps. In that case, distances d.sub.t,MiN and d.sub.t,MAX (not represented but calculable in the same fashion) are calculated and compared with the predetermined distance range to establish whether the target is within or outside of the range. If one of the distances does not fall within the predetermined distance range, the first device may be configured to determine that the target is outside of the range, or make the determination conditional on how much the value is outside the range relative to how much the other value is inside the range. That can be done, for instance, in the following manner:

(28) $\{\begin{array}{c}{\Delta }_{\mathrm{MIN}}=.Math.d_{t,\mathrm{MIN}}-d_{\mathrm{ab},\mathrm{MIN}}.Math.\\ {\Delta }_{\mathrm{MAX}}=.Math.d_{t,\mathrm{MAX}}-d_{\mathrm{ab},\mathrm{MAX}}.Math.\end{array}$

(29) If the value outside the range is d.sub.t,MIN and the value inside the range is d.sub.t,MAX the first device may determine that the target is within the range if:
Δ.sub.MAX>Δ.sub.MIN

(30) Minimum and maximum predetermined distances may be necessary whenever it is not accurately established what is the distance between the predetermined locations of the second devices, for example because the values have not been calibrated for the actual target. When the target is a person, there is variability in heights, widths and lengths, so if the predetermined distance has been set for people with a certain height, a user with a different height will have another predetermined distance between the locations. Hence, the predetermined distances can be set for people of different heights, and the determination be made with ranges of predetermined distances (or predetermined angles as explained next).

(31) The determination of whether the target is within the predetermined distance range is made, in some embodiments, by comparing the angle difference with a predetermined angular range. In this example, minimum and maximum angles A.sub.MIN, A.sub.MAX have been represented for the sake of clarity only, which delimit the predetermined angular range. By comparing the angular difference (e.g. B′ minus A) with the A.sub.MIN, A.sub.MAX, the first device 10 establishes whether the target is within or outside of the predetermined distance range.

(32) FIG. 4 shows an exemplary way of estimating distance of a target in accordance with embodiments.

(33) Albeit not illustrated, the target has two second devices 20a, 20b at predetermined locations thereof. The predetermined distance or gap d.sub.ab between the two devices 20a, 20b is known.

(34) A first device 10 measures angles of arrival A, B of signals wirelessly received from respective second devices 20a, 20b. The angles A, B are measured with respect to a predetermined direction (in this example it is parallel to dashed line h) of the first device 10. The angles A and B yield the angle difference between the two second devices 20a, 20b (corresponding to directions thereof Da, Db), which is A plus B due to them being at different sides of the predetermined direction.

(35) With the angles A, B and the gap d.sub.ab, the first device digitally provides two right triangles, one with base x and one with base y (with x plus y being g). Each of the two right triangles have one edge (h) that is parallel to the predetermined direction, which is known by the first device as it is a direction set by it as a reference for angle measurements. A system of equations can be defined by the first device to determine the distance d.sub.t, which ranges from the first device 10 to the middle point of the predetermined distance or gap d.sub.ab, by means of trigonometrical relationships. An exemplary system is as follows:

(36) $\{\begin{array}{c}{d}_{\mathrm{ab}}=x+y\\ \tan \left(A\right)=x/h\\ \tan \left(B\right)=y/h\end{array}$

(37) By calculating the length h, the length d.sub.t corresponding to the distance to the target can be computed as well, for instance by using trigonometrical relationships on a triangle formed by edges d.sub.t and h. In some cases, for instance depending on the considered predetermined distance range and/or the gap d.sub.ab, the length h is a good estimation of the length d.sub.t, thus the first device may simplify the evaluation by taking the length h as the distance to the target.

(38) It will be noted that other systems aside from the one above are possible as well, including systems for calculating the length of edges a and b.

(39) FIGS. 5A-5B show another exemplary way of estimating distance of a target in accordance with embodiments.

(40) In FIG. 5A, a predetermined direction PD of the first device 10 is shown, and direction Da, Db are represented based on the angles of arrival A and B that the first device 10 has measured from wireless signals received from two second devices not shown in FIG. 5A. Although not illustrated in FIG. 5A, the first device 10 has data indicative of the gap that is to exist between the two second devices.

(41) In FIG. 5B, the first device 10 has digitally provided an isosceles triangle with edges parallel to the directions Da, Db along which the two second devices 20a, 20b shall be based on the measured angles of arrival. The first device 10 takes the bisector from the vertex that the first device 10 is on, whose line is to correspond to the distance from the first device 10 to the target at the point it intersects the base of the isosceles triangle, preferably forming a right angle with the base. Owing to the knowledge of the gap d.sub.ab, the first device finds the base of the isosceles triangle which has the length d.sub.ab, which automatically locates the positions of the second devices 20a, 20b. Once the base is provided, the distance d.sub.t can be computed by e.g. using trigonometrical relationships: the angles from the vertex where the first device 10 is are, at each side of the segment d.sub.t, B minus A divided by two.

(42) FIG. 6 shows yet another exemplary way of estimating distance of a target in accordance with embodiments.

(43) A first device 10 wirelessly receives a plurality of signals from at least two second devices 20a, 20b that are at predetermined locations of a target (not shown). Each antenna 14 of the plurality of antennas 14 of the second devices 20a, 20b causes the transmission of a wireless signal for a same data packet, the processing of which by the first device 10 enables determination of the angle of departure A, B of the signals that were transmitted by the respective second device 20a, 20b.

(44) The first device 10 thus has the angles of departure A, B, and the predetermined distance or gap d.sub.ab, and one exemplary way of calculating the distance d.sub.t is as follows.

(45) With the angles A, B, the first device 10 digitally establishes directions Da, Db where the two second devices 20a, 20b are. And with the predetermined distance or gap d.sub.ab, the first device 10 digitally establishes edges a and b of the triangle. In a fashion similar to that explained with reference to the embodiments of FIG. 4, the first device 10 computes length h that produces respective right triangles on each side, one with base x and one with base y. Upon solving a system of equations, the first device 10 may either consider length h as the distance it is from the target, or compute distance d.sub.t whose endpoints are the first device 10 and the middle point of the base of the large triangle having gap d.sub.ab as one of the edges, and a and b as the other two edges.

(46) By way of example, the distance d.sub.t, which is a median of the triangle, can be computed with a formula like the following one:

(47) $d_t=\sqrt{\frac{a^2+b^2-d_{\mathrm{ab}}^2}{4}}$

(48) It will be apparent for the person skilled in the art that there are other possible formulas for calculating said distance, all of which falling within the scope of the present disclosure.

(49) In this text, the term “includes”, “comprises” and its derivations (such as “including”, “comprising”, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.

(50) On the other hand, the disclosure is obviously not limited to the specific embodiment(s) described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of materials, dimensions, components, configuration, etc.), within the general scope of the invention as defined in the claims.