Locations between vehicle and identifiers with period adjustment
The UWB location planning method addresses the issue of overlapping location cancellations by using distinct period values for multiple identifiers, ensuring accurate and continuous localization by minimizing overlap and cancellation, thus maintaining precise tracking.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- VALEO COMFORT & DRIVING ASSISTANCE
- Filing Date
- 2024-12-16
- Publication Date
- 2026-06-19
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Title of the invention: Vehicle-to-identifier localization with period adjustment technical field
[0001] This disclosure relates to a method of using a UWB (acronym for the English "Ultra Wide Band") system, a UWB system configured to be used according to such a method, a computer program for carrying out such a method and a medium for such a program. Technical background
[0002] Vehicles equipped with a UWB system now exist, comprising one or more UWB anchors (also called sensors) installed in the vehicle. Such a UWB system generally records a set of portable identifiers (such as key fobs) and is then able to determine the position of each of these portable identifiers from periodic UWB location checks between each of the portable identifiers and the system's UWB anchors. Such UWB systems are thus capable of locating several identifiers simultaneously and, depending on the identifier location, executing different vehicle functions (such as, for example, unlocking the doors and / or starting the vehicle when a user approaches the vehicle).
[0003] To perform these location tracking, each wearable identifier can be configured to negotiate communication parameters with the UWB system, for example, when the latter enters a certain perimeter around the vehicle. The negotiated parameters may or may not include the frequency of location tracking to be performed by the identifier. The system and the identifier are then configured to program UWB location tracking according to the negotiated parameters. The UWB system and the wearable identifier can then be configured to perform UWB location tracking according to the established UWB location programming. [Fig. 1] shows an example of UWB location tracking programmed with a set of two wearable identifiers: a first identifier 100 and a second identifier 200.In particular, communication with the first identifier 100 includes UWB locations 111, 112, 113 programmed according to a first periodicity, and communication with the second identifier 200 includes UWB locations 211, 212, 213 programmed according to a second periodicity.
[0004] When several locations are programmed at the same time (i.e., in such a way that they would overlap if executed, the intervals (given the time intervals on which they are programmed having a non-zero intersection), existing UWB systems generally retain only one location, and all other UWB locations are therefore canceled (for example, only the one programmed first can be retained). Such cancellation effectively reduces the risk of interference between UWB exchanges of UWB locations if they were executed simultaneously. For example, in [Fig. 1], UWB location 112 of the first portable identifier 100 and UWB location 212 of the second portable identifier 200 are programmed at the same time, and the system therefore cancels UWB location 212, which was programmed slightly later, so that during execution, only the remaining UWB location 112 is executed.
[0005] One limitation is that these UWB location cancellations reduce the number of locations ultimately executed. In particular, they penalize one of the identifiers more than the others each time. In such a situation, when several successive locations are canceled for an identifier, several seconds may elapse before the next location is executed, thus causing malfunctions in the vehicle's functionalities that use the identifier's position. For example, the user may approach the vehicle without it automatically unlocking, as is normally the case with this function.
[0006] Therefore, there is a need for an improved UWB location planning process. Summary
[0007] A method for using a vehicle system comprising one or more UWB anchors (hereafter referred to as the "use method" or "method") is proposed. The UWB system has recorded a plurality of portable identifiers. The method includes detecting a first portable identifier around the UWB system. The method includes performing periodic UWB location checks with the first portable identifier. The UWB location checks with the first identifier are spaced according to a first period value. The method includes detecting a second portable identifier around the UWB system. The method includes calculating a second period value. The difference between the first and second period values is greater than or equal to the duration of a UWB location check. The method includes performing periodic UWB location checks with the second portable identifier.UWB locations with the second identifier are spaced according to the second calculated period value.
[0008] The first and second period values may have a number of common factors less than or equal to a predetermined threshold, for example a threshold equal to 2.
[0009] The first and second period values can be relatively prime numbers.
[0010] The first and / or second period value may be a prime number.
[0011] The first period value can be equal to the result of the product of a coefficient multiplier and a predetermined minimum duration. The second period value may not be divisible by the predetermined minimum duration.
[0012] The method may further include detecting a third portable identifier and calculating a third period value. The difference between the second and third period values may be greater than or equal to the duration of each UWB location. The first, second, and third values may form an ordered sequence of numbers. The method may then include implementing periodic UWB locations with the third portable identifier. The UWB locations with the third identifier may be spaced according to the calculated third period value.
[0013] The first, second and third period values can be numbers that are pairwise relatively prime.
[0014] A vehicle UWB system comprising one or more UWB anchors is also proposed. The UWB system is configured for use according to the operating method.
[0015] A computer program for a vehicle UWB system is also proposed. The computer program includes instructions which, when the program is executed by a processor of the vehicle UWB system, cause the system to be used according to the operating method.
[0016] A computer-readable storage medium is also proposed on which said computer program is recorded. Brief description of the figures
[0017] Non-limiting examples will be described with reference to the following figures:
[0018] [Fig.1] illustrates an example of an existing UWB location planning solution with handheld devices.
[0019] Figure [Fig. 2] illustrates an example of a flowchart of the planning process.
[0020] Figure 3 illustrates an example of UWB location with a portable identifier.
[0021] Figure 4 illustrates an example of programming a UWB localization session periodicals.
[0022] Figures [Fig. 5] and [Fig. 6] illustrate an example of UWB localizations carried out with two portable identifiers according to the method.
[0023] Figures [Fig. 7], [Fig. 8], [Fig. 9], [Fig. 10], [Fig. 11] and [Fig. 12] illustrate examples of results from using the process
[0024] Fig. 13 illustrates an example of a vehicle system.
[0025] Fig. 14 illustrates an example of a portable identifier. Detailed description
[0026] With reference to the flowchart in [Fig. 2], a method for using a vehicle system comprising one or more UWB anchors (hereafter referred to as the "use method" or "method") is proposed. The UWB system has recorded a plurality of wearable identifiers. The method includes a detection S10 of a first wearable identifier around the UWB system. The method includes an implementation S20 of periodic UWB locations with the first wearable identifier. The UWB locations with the first identifier are spaced according to a first period value. The method includes a detection S30 of a second wearable identifier around the UWB system. The method includes a calculation S40 of a second period value. The difference between the first period value and the second period value is greater than or equal to the duration of a UWB location.The method includes an S50 embodiment of periodic UWB locations with the second portable identifier. The UWB locations with the second identifier are spaced according to the second calculated period value.
[0027] The method offers improved utilization of the vehicle's UWB system.
[0028] Indeed, the method improves the localization of the different portable identifiers by reducing the risk of overlap between the programmed locations of the two portable identifiers. In particular, in the event of overlap, the period values used prevent the identifier whose programming is canceled from also undergoing a further localization cancellation in the next period. The method thus reduces the risk of several successive localization cancellations for the same identifier, thereby preventing an excessively long gap without localization. Ultimately, the method allows for the sensitive and precise localization of all portable identifiers.
[0029] After or during the execution of the localizations, the method of use may include determining the position of each of the wearable identifiers from the localizations that have been executed. For example, for each wearable identifier, the execution of a localization involving the wearable identifier may include providing a relative position of the wearable identifier with respect to the UWB system. In particular, each localization may include UWB exchanges between the wearable identifier and one or more UWB anchors (also called "sensors") of the system (for example, all the anchors) to determine the respective distances between the wearable identifier and each of the anchors. Each localization may then include determining the relative position of the portable identifier in relation to the UWB system from the determined distances (the position corresponding for example to the intersection of spheres drawn from the anchors and having as radii the calculated distances).
[0030] Each distance to an anchor can be measured by exchanging a UWB signal between the identifier and the anchor and calculating a time-of-flight between the identifier and the anchor during this exchange. This time-of-flight can be the time taken by the exchanged signal to travel to or from the identifier and the anchor. The time-of-flight can be calculated by the identifier or the anchor, and can be performed in any way. For example, each measurement can include recordings of the times the exchanged signal is sent and received, and the calculation can be performed by subtracting the time taken by the signal to travel to or from these recordings. Each measurement can then include subtracting the distance between the identifier and the anchor from this time-of-flight. For example, each measurement can include multiplying a signal velocity by the calculated time-of-flight.The signal speed can, for example, be a predetermined and known speed for this type of signal (e.g., stored in the identifier or system memory). The signal speed, i.e., the propagation speed of UWB waves, can be the speed of light (a constant stored in memory).
[0031] For each wearable device, successive localizations performed during communication with the wearable device can allow the real-time determination of its position. For example, each localization can provide a position of the wearable device relative to the UWB system at a given instant, and the set of all performed localizations can provide an evolution of its position over time. The method of use can thus include determining the evolution of the wearable device's position from the periodic UWB localizations performed.
[0032] The method of use may also include one or more uses of the determined relative positions of the portable identifier. For example, the method of use may include activating one or more vehicle functions depending on the position of the portable identifier. For example, the function may include locking the vehicle when it is determined that the portable identifier is outside the vehicle, for example, after a predetermined time has elapsed between the time it is determined that the portable identifier is outside. In some examples, the function may include selectively unlocking one or more vehicle openings (for example, a driver's door, a passenger door, or a vehicle trunk) depending on the determined relative positions of the portable identifier.For example, the functionality may include unlocking the driver's door or the vehicle's trunk when... The wearable device approaches the driver's door or trunk. In other examples, the functionality may include activating one or more vehicle functions, such as turning on the music or adjusting the mirrors to suit the person wearing the wearable device, which is positioned near the driver's seat. The method of use may include any combination of these examples of functionality.
[0033] The method of use is now discussed. The steps of the planning process can be executed by the vehicle's UWB system. Each step of this process is now discussed in more detail.
[0034] The UWB system has registered a plurality of portable identifiers (or wearable identifiers). The term "wearable identifier" refers to a mobile object identifiable by the vehicle, and whose location, for example, authorizes or prevents one or more (specific) actions of the vehicle. For example, the identifier can be used to unlock the vehicle and / or start the vehicle's engine. For example, the process can include unlocking the vehicle when the identifier is located near the vehicle, or starting the engine when the identifier is inside the vehicle. The wearable identifiers registered by the system can include one or more of the vehicle's remote key fobs (called "keyfobs"). The UWB system can also have registered other wearable identifiers, such as third-party devices, i.e., devices manufactured by a company other than the one manufacturing the vehicle's UWB system.For example, third-party devices can be smart devices, such as mobile phones or smartwatches. These other wearable identifiers may currently be beyond the system's reach.
[0035] The vehicle and each wearable identifier can be configured to communicate using the UWB (Ultra Wide Band) communication protocol. UWB can refer to a communication protocol, for example, that specified by IEEE 802.15.4. This protocol may include an initialization phase with an exchange of communication parameters (such as the location frequency, the period value, and / or the duration of each location). The wearable identifiers can also be configured to communicate with the vehicle using the BLE (Bluetooth Low Energy) communication protocol.Some wearable devices (for example, all of them) can also be configured to communicate with the vehicle using one or more other communication protocols, such as the NFC (Near Field Communication) protocol. For each device... Portable, UWB communication with the vehicle can only be initiated if a prior connection has been established according to the BLE protocol.
[0036] The method includes, for each wearable ID, an S10 detection of a first wearable ID around the UWB system. The method can perform this S10 step while a first user wearing the first wearable ID approaches the vehicle. For example, the method can perform this S10 step while the user is traveling to their vehicle, that is, from a place of residence (for example, their home, office, hotel, or business such as a shop or restaurant) to the vehicle.
[0037] S10 detection can occur upon entry of the wearable identifier into a predetermined UWB perimeter around the vehicle. S10 detection can, for example, consist of an initial UWB exchange between the system and the wearable identifier. For instance, the system and the identifier can be configured to perform UWB communication trigger tests, and S10 detection can include the success of one of these tests. Each test can fail when no response signal is received (for example, after a predetermined listening period), or succeed when a response signal is received during the listening period. This initial UWB exchange can include the system sending a UWB signal followed by the identifier receiving that signal. Alternatively, the UWB signal can be sent by the identifier and then received by the system.The success of this first UWB exchange between the identifier and the system can mean that the portable identifier is within the UWB perimeter, that is, it is within range of the system. Before the success of this first UWB exchange, one or more unsuccessful UWB exchange attempts may have been made (because the identifier was not yet within the UWB perimeter at that time).
[0038] The system and the identifier can be configured to perform such UWB communication trigger tests after a prior connection has been established according to the BLE protocol. The UWB communication trigger tests can begin when the portable identifier is detected within a BLE perimeter around the vehicle that is larger than the UWB perimeter.
[0039] After detection S10, the method includes an implementation S20 of periodic UWB localizations with the first wearable identifier. The localizations can be performed directly after successful testing. The localization implementation S20 may include a preliminary phase of negotiating communication parameter(s) between the wearable identifier and the system. This preliminary phase may, in particular, include the system sending a first period value to the wearable identifier, optionally followed by validation of this first value by the wearable identifier. Alternatively, the periodicity of the first identifier may The first period value can be programmed to a value without being provided by the system. The first period value is the expected time between two successive locations for this first identifier. Each period value (i.e., the first, second, and third values) can be a positive number, such as an integer, representing a duration, for example, in milliseconds. The system can store this first period value, for example, in system memory. The first identifier can also store this first value in its own memory. The system can directly send the first period value to be used, or alternatively, it can send any information that allows this duration to be retrieved. For example, the system can send the corresponding frequency of UWB locations. In this case, the wearable identifier can be configured to retrieve the first period value corresponding to the received information.
[0040] After this preliminary phase, step S20 can include periodic UWB localizations with the first portable identifier. The UWB localizations with the first identifier are spaced according to the first period value sent by the system to the identifier. This means that the time elapsed between the start times of each pair of successive localizations is equal to this first period value. In other words, a UWB localization can be performed every At; milliseconds, where At; is the first period value.
[0041] The method then includes the S30 detection of a second wearable device. The second wearable device can be detected during the UWB location process with the first wearable device in step S20. The S30 detection of the second wearable device can be performed in the same way as the S10 detection of the first wearable device. This second wearable device may initially be out of range of the vehicle, and the user wearing it may approach the vehicle. For example, as previously discussed, the S30 detection of the second wearable device may include performing an initial UWB exchange between the system and the second wearable device after the latter has entered the UWB perimeter around the vehicle.
[0042] After detection S30, the method includes calculating S40 a second period value for the second portable identifier. The calculated second period value is the expected time between two successive locations for this second identifier. The second period value may be greater than the first period value. The second period value is calculated such that the difference (for example, in absolute value) between the first and second period values is greater than or equal to the duration of a UWB location. The calculation S40 may include calculating a minimum value equal to the sum of the first period value and the duration of a UWB location, and a selection a second value greater than or equal to this minimum value. For this calculation, the first period value can be retrieved from system memory. In some examples, the second period value can also be less than a maximum value. The process can calculate this maximum value, for example, from a desired minimum frequency of UWB locations for the second portable identifier. The maximum value can, for example, be equal to twice the first period value, minus the duration of one location (2 x di - di, where di is the first period value and di is the duration of one location). After the SO calculation step, the calculated second period value, and optionally also the calculated minimum and maximum values, can be stored in system memory.
[0043] UWB locations can have a duration less than half the periodicity of the identifier involved. The period value of each portable identifier can therefore be more than twice the length of the UWB locations performed with that identifier. This makes it possible to limit the occupancy of UWB locations within the time available to perform the exchanges.
[0044] When the locations with the two portable identifiers have different durations, the method can consider, during calculation S40, the duration of those with the identifier having the longer UWB locations. For example, the UWB locations with the first portable identifier may have a first duration, and the UWB locations with the second portable identifier may have a second duration. In this case, the difference between the first period value and the second period value may be greater than or equal to the maximum between the first and second durations. The calculation of the minimum value may include determining the portable identifier with the longer locations and adding the first period value to the duration of the locations for that determined identifier.
[0045] After calculation S40, the method includes an embodiment S50 of periodic UWB locations with the second portable identifier. As with the first portable identifier, the S40 location implementation may include a preliminary phase of negotiating communication parameter(s) between the second portable identifier and the system. This preliminary phase may, in particular, include the system sending the second calculated period value to the second portable identifier, optionally followed by validation of this second value by the second portable identifier. As with the first identifier, the system may directly send the second period value to be used, or any information enabling the retrieval of this value (such as the corresponding frequency).
[0046] After this preliminary phase, step S50 may include periodic UWB locations with the second portable identifier spaced according to the second period value sent by the system to the identifier. This means that there is an interval between The start times of each pair of successive localizations are equal to the second period value. In other words, a UWB localization can be performed every 2 milliseconds, where 2 is the second period value. The system then performs both UWB localizations with the second portable identifier and those with the first portable identifier (i.e., using two different periodicities for the two portable identifiers involved). The UWB localizations with the second portable identifier are then interleaved between those programmed with the first portable identifier.
[0047] During the S40 calculation, the method can select the second period value in any way. For example, the method can arbitrarily select the second value from all values between the minimum and maximum values calculated as previously described. Alternatively, the method can include one or more additional conditions for selecting this second value. For example, the method can require that the first and second period values have a number of common factors less than or equal to a predetermined threshold. This threshold could, for example, be 2. This additional condition improves subsequent communication between the two wearable identifiers. Indeed, having a reduced number of common factors helps control the risk of overlap between the locations performed between the two identifiers, and therefore the probability of having to cancel some of them.The process then allows, for example, the use of a reduced number of common factors when the periodicities of the identifiers are long, in order to minimize the probability of overlap in this critical case. Controlling the number of common factors in this way ultimately improves the accuracy of locating the two portable identifiers.
[0048] In examples, the method can, for instance, select the first and second period values such that these values are relatively prime. In other words, the predetermined threshold of common factors between these two values can be equal to one (the only common factor between such numbers being 1). The first and second period values can thus have only one common factor: 1. At step S40, the method can therefore, for example, select a second period value that has no other common factor with the first period value than 1. Such a selection further improves subsequent communication between the two portable identifiers. Indeed, having no other common factor than 1 further reduces the risk of overlap between locations performed with the two identifiers, and therefore the probability of having to cancel them.This ultimately improves the accuracy of locating the two portable identifiers.
[0049] In examples, the method can also select period values that are prime numbers. This ensures that no other period value has a common factor other than 1 with the selected values. For example, the first period value can be a prime number. In this case, the second period value can be randomly selected from the set of values greater than or equal to the calculated minimum value, and this value necessarily has only 1 as a common factor with the first value. Alternatively, the second period value can be a prime number. In this case, the second period value will never have a common factor with the first period value. In examples, both the first and second period values can be prime numbers.In this case, it also reduces the risk of overlap with any other identifier that will have a different period value.
[0050] Periodic UWB localizations are defined as UWB localizations performed at fixed, i.e., regular, intervals. For example, for a set of successive periods (of substantially equal duration), the system and the portable identifier can perform a UWB localization at each period. The duration of these successive periods corresponds to the periodicity of the portable identifier. It is equal to the first period value for the first portable identifier and to the second period value for the second portable identifier.
[0051] The position of the UWB location can be the same for each period. For example, each period can comprise an identical number of successive slots (of substantially equal duration), and each UWB location can always be located on the same slot of each period (for example, the first one). UWB locations can thus be implemented with a fixed frequency.
[0052] Each UWB location may include UWB exchanges between the portable identifier and the system's UWB anchors. Each UWB exchange may consist of frame transmissions between the identifier and one or more UWB anchors. In particular, each UWB location with a portable identifier may include the transmission of UWB frames by the portable identifier, followed by the UWB system listening for the transmitted UWB frames. The preliminary negotiation phase may include exchanges and agreement on the timing of the transmission and reception of these frames by the system and the identifier at each location.
[0053] In examples, the periodicity of the first portable identifier (i.e., the first period value) can be equal to the product of a respective multiplier coefficient (called the "RAN multiplier") and a predetermined minimum duration. For example, the first portable identifier can be configured to perform a localization on each successive time interval of The duration Ti (Ti being the first period value used by the portable identifier). In this case, the duration Ti can be equal to n^(iπ) Atmini, where nRAN i is the respective multiplier of the first portable identifier and Atmini is the predetermined minimum duration. The multiplier can be an integer. The predetermined minimum duration Atmini can be defined by a standard (e.g., 96 ms) and can be the same for all relevant portable identifiers. The respective multiplier can be initially negotiated by each identifier with the system, for example, during the pre-determination phase.
[0054] In this case, the second period value may not be divisible by the predetermined minimum duration Atmini. The system can select, at calculation step S40, a second period value that is not divisible by the predetermined minimum duration Atmini. Such a selection of a second period value further improves subsequent communication between the two portable identifiers, reducing the risk of overlap between locations performed with the two identifiers, and therefore the probability of having to cancel them.
[0055] In examples, steps S40 and S50 can be repeated each time a new wearable identifier is detected. For example, the method may include detecting a third wearable identifier, calculating a third period value for this third wearable identifier, and performing periodic UWB location checks with this third wearable identifier based on the calculated third period value. This third wearable identifier may initially be out of range of the vehicle, and the user wearing it may approach the vehicle. The detection of this third wearable identifier may be performed in the same way as the S10 and S30 detections of the first and second wearable identifiers.For example, as previously discussed, the detection of the third wearable device may involve performing an initial UWB exchange between the system and the third wearable device after it has entered the UWB perimeter around the vehicle. The third wearable device may be detected during the UWB localization process with the first and second wearable devices.
[0056] After the detection of the third portable identifier, the method may include calculating the third period value for the third portable identifier. The calculated third period value is the expected time between two successive locations for this third identifier. The third period value may be greater than the first and second period values. More precisely, the first, second, and third values may together form an ordered sequence of numbers, for example, a sequence of increasing positive integers. The third period value may be calculated such that the difference (for example, in The absolute value between the second and third period values must be greater than or equal to the duration of a UWB localization (for example, the duration of the longest of all such localizations). Similar to the calculation of the second value, the calculation of the third value may involve calculating the sum of the second period value and the duration of a UWB localization, and selecting a third value greater than or equal to that sum. The second period value may be retrieved from system memory. The calculated third period value may also be stored in this system memory.
[0057] After calculating the third period value, the method may include performing periodic UWB localizations with the third portable identifier based on the calculated third period value. As with the first and second portable identifiers, performing these localizations may include a preliminary phase of negotiating communication parameter(s) between the third portable identifier and the system. This preliminary phase may include, in particular, the system sending the calculated third period value to the third portable identifier, optionally followed by validation of this third value by the third portable identifier. As with the first and second identifiers, the system may directly send the third period value to be used, or any information enabling the determination of this duration (such as the corresponding frequency, for example).
[0058] After this preliminary phase, the method can include periodic UWB localizations with the third portable identifier spaced according to the third period value sent by the system to the identifier. This means that the time elapsed between the start times of each pair of successive localizations is equal to this third period value. In other words, a UWB localization can be performed every At 3 milliseconds, with At 3 being the third period value. The system then performs both the UWB localizations with the third portable identifier and those with the first and second portable identifiers (i.e., using three different periodicities for the three portable identifiers involved). The UWB localizations with the third portable identifier are then interleaved between those programmed with the first and second portable identifiers.This selection of a third period value improves communication with the three wearable devices. It reduces the risk of overlap between locations obtained with the three wearable devices, and therefore the likelihood of having to cancel some. Ultimately, this improves the accuracy of the location tracking for all wearable devices.
[0059] In examples, the method can select the second and third period values such that the first, second and third period values These three values must be pairwise relatively prime. This means that each pair of values among these three values is a pair of numbers that are relatively prime. This further reduces the risk of overlap between locations with the three identifiers.
[0060] Examples will now be described with reference to Figures 3 to 14.
[0061] Figure 3 illustrates an example of UWB localization with a portable identifier. Localization includes UWB exchanges between the portable identifier and the vehicle system (the UWB exchanges consisting of frame transmissions between the identifier and the system's UWB anchors). UWB localization begins with the portable identifier sending UWB frames to the UWB anchors. In particular, localization initially comprises two 410 transmissions of a frame in the first two time slots from the identifier 400 to each of the UWB anchors 401, 402, and 403. Each slot can last between 1 and 3 ms. Each slot is, for example, 2 ms in this example. Localization includes the UWB anchors listening for these 410 UWB frames sent by the portable identifier 400 in these first two time slots. After this first phase, the anchors respond by sending, one after the other, a respective frame to the portable identifier.Specifically, the localization process involves, successively and within a respective time slot, the transmission of a frame by each of the UWB anchors (frame 412 for 401, frame 413 for 402, and frame 414 for 403) to the portable identifier 400. The portable identifier is configured to listen for and receive these frames 412, 413, and 414 sent successively by the anchors. The localization process then involves two transmissions, 415, by identifier 400, of a frame in the last two time slots to each of the UWB anchors 401, 402, and 403 of the system. These two transmitted frames are listened for and received by the portable identifier 400.
[0062] The duration of the UWB localization “RR_time” can be calculated from the following formula: RR_time = Ranging_Slot_Time * ( Number_ of_Responder + 4), in which “Ranging_Slot_Time” is the duration of each slot and “Number_ of_Responder” is the number of anchors in the system.
[0063] The localization process then includes determining the distances between the portable identifier 400 and each of the UWB anchors 401, 402, and 403 of the system. Each distance to an anchor can be measured from the UWB frames exchanged between the portable identifier and the anchor and a time-of-flight calculation between the identifier and the anchor. This time-of-flight is the time taken for each frame to travel to or from the identifier and the anchor. The time-of-flight can be calculated by the identifier or the anchor, and can be performed in any way. For example, each measurement can include records of the times the exchanged frames were sent and received, and the calculation can be performed by deducting the time from these records. taken by each frame to travel to or from the anchor point. Each measurement can then include a deduction of the distance between the identifier and the anchor point from this time of flight. For example, each measurement can involve multiplying the speed of the signal carrying the UWB frame by the calculated time of flight. The signal speed can be a predetermined and known speed (e.g., stored in the identifier's or system's memory).
[0064] The localization process then includes determining the relative position of the wearable identifier with respect to the UWB system based on the determined distances. In particular, the position determination includes determining the intersection of spheres calculated on a plane representing the ground on which the car is located and on which the user wearing the identifier is walking. The spheres originate from the system's anchors and have radii equal to the calculated distances.
[0065] The deprogramming of such a location is now discussed. A location is executed by both the system and the identifier. However, the system can cancel a location without informing the identifier. The system may, in fact, only manage one location at a time. Each identifier manages its locations through a specific session. During an overlay, the session containing the first programmed location is executed, and the second session waits for the next period to attempt a location between the portable identifier and the vehicle's anchors.
[0066] To cancel a location with an identifier, the system can, for example, cancel listening to the frames sent by the portable identifier. For example, the cancellation could include canceling listening to the first 410 frames sent by the identifier to each of the anchors. In some examples, the cancellation could also include canceling the sending of the 412, 413, and 414 frames successively transmitted by each of the anchors thereafter, and / or canceling listening to the last 415 frames sent by the identifier 400.
[0067] Figure 4 illustrates an example of programming a session of periodic UWB locations between a handheld identifier and a UWB system. During the session, the periodic UWB locations of the UWB locations are performed at fixed, more or less regular intervals. The respective programming comprises, for a set of successive periods (of substantially equal duration), one UWB location for each period. The duration of these successive periods corresponds to the periodicity of the handheld identifier.
[0068] In examples, the position of the location within each period may vary. Each period 422 may comprise an identical number of successive slots 424 (of substantially equal duration), and the UWB location may be programmed within one of these slots 424. Each UWB location may be realized always within the same time slot of each period (for example, the first one). Each 424 slot is itself divided into time intervals (called "slots"). Location can include UWB exchanges between the wearable identifier and the system within each of these time intervals.
[0069] Figures 5 and 6 illustrate an example of UWB localization performed with two portable identifiers according to the method. The method includes detecting a first portable identifier 510 around the UWB system. The method includes performing periodic UWB localizations 511 and 512 with the first portable identifier. The UWB localizations with the first identifier are spaced according to a first period value 513. The method includes detecting a second portable identifier 520 around the UWB system. The method includes calculating a second period value 523. The difference between the first period value 513 and the second period value 523 is greater than or equal to the duration of the UWB localizations 521, 522 with the second portable identifier 520 (which are longer than those 511, 512 of the first 510).The method calculates the sum of the first period value 513 and the duration of one of the locations 521, 522 with the second portable identifier 520, and then selects a second period value 523 that is greater than or equal to this sum. The method then includes an embodiment of periodic UWB locations 521, 522 with the second portable identifier. The UWB locations 521, 522 with the second identifier 520 are spaced according to the second calculated period value 523.
[0070] The method improves the localization of the two portable identifiers 510, 520. Specifically, the method ensures that two successive localizations for the same identifier are not canceled. In particular, if localizations performed with the two identifiers overlap, one of the overlapping localizations is canceled, and only the one that begins first is retained. In such a situation, the method ensures that the next localization performed with the identifier whose localization is canceled will be carried out. Indeed, the calculated periodicity for the second portable identifier ensures that this next localization will not overlap with a localization of the first identifier.
[0071] In the situation illustrated in [Fig. 5], for example, location 511 with the first portable identifier and location 521 with the second portable identifier are programmed simultaneously. Since only the one programmed first is executed, the process only executes location 511 with the first identifier 510, and location 521 with the second identifier 520 is therefore canceled. Locations with the second portable identifier 520 are executed according to a second period value 523 that is greater than or equal to a sum of the first period value 513 and the duration of a UWB location. At the In the following period, the subsequent location 522 with the second identifier 520 is necessarily performed after the completion of location 512 with the first portable identifier 510. The two locations are therefore not superimposed, and the process thus ensures that the subsequent location 522 with the second identifier 520 is not canceled. The process therefore guarantees that an excessively long period does not elapse without a location for either of the two identifiers.
[0072] In the second situation illustrated in [Fig. 6], a new overlap occurs, but this time location 515 with the first portable identifier begins after location 524 with the second portable identifier. Therefore, it is location 515 with the first portable identifier that is canceled. In the following period, since the second period value 523 is greater than or equal to a sum of the first period value 513 and the duration of a UWB location, the next location 515 of the first identifier 510 necessarily begins before location 524 with the first portable identifier 510. Therefore, this time it is location 524 with the second portable identifier 520 that is canceled. The method thus ensures that there is no further cancellation of location for the first portable identifier 510.In both situations, the process ultimately ensures that no excessively long period of time passes without location tracking for either of the two identifiers.
[0073] Figures 7 and 8 illustrate examples of results obtained using the method. In particular, these figures demonstrate the advantage of selecting period values that are relatively prime. Specifically, Figure 7 shows the evolution of the overlap (or interference) rate obtained in localizations with two identifiers. The figure shows, in particular, the evolution of this rate (Y-axis) as a function of the periodicity of one of these two portable identifiers (X-axis). The figure shows the evolution of this rate for a first identifier 701 and for a second identifier 703. The figure also shows the greatest common divisor 705 of the periodicities of the two identifiers. Both identifiers produce localizations of the same duration, equal to 22 ms. The first identifier has a fixed periodicity of 288 ms, and the periodicity of the second varies between 310 and 339 ms.
[0074] Fig. 7 shows that when the periodicity (i.e., the second period value) of the second portable identifier is a prime number with the periodicity (i.e., the first period value) of the first portable identifier (a single common factor of unit 1), the overlap rate for the second portable identifier decreases (the overlap rate increases when the greatest common divisor 705 is not zero, in particular when the second value is equal to 312 ms, 320 ms, 324 ms and 336 ms).
[0075] Figure 8 also shows the evolution of the overlap rate obtained in exchanges with two identifiers as a function of the periodicity of the first portable identifier. However, the periodicity of the first identifier is this time fixed at 271 ms, which is a prime number. The figure shows that the overlap rate is low in this case for both identifiers. Another advantage is that the overlap rate becomes the same for both identifiers, regardless of the periodicity value of the second portable identifier.
[0076] To further reduce the overlap rate, the process can increase the periodicity. The limit may be determined by the availability of telemetry data to manage access or startup functions, which must be balanced against the system's energy consumption.
[0077] Figures 9 to 12 show examples of results obtained using the planning method in different situations where five portable identifiers are located around the vehicle: two key fobs 801, 802, and three third-party devices (smartphones). In each illustrated situation, the key fobs are identical 801, 802, but the three third-party devices vary each time. The figures show the evolution of the percentage of times more than one second elapsed between two locations (Y-axis) for each of these five identifiers. The figure specifically shows the evolution of this percentage as a function of the frequency of the first 801 of the two key fobs (X-axis).
[0078] The three tier devices are from manufacturer A 803, 804, 805 in the situation shown in [Fig. 9], from manufacturer B 813, 814, 815 in the situation shown in [Fig. 10], and from manufacturer C 823, 824, 825 in the situation shown in [Fig. 11]. In the situation shown in [Fig. 12], the tier devices come from different manufacturers, and the figure shows the percentage evolution for a tier A 833 device, a tier B 835 device, and a tier C 834 device. The characteristics of the portable identifiers used are shown in Table 1 below.
[0079] [Tables 1] Portable identifier, Multiplier coefficient, Average periodicity, Slot length: Manufacturer A 3,288 ms 2 ms, Manufacturer B 2,192 ms 1 ms, Manufacturer C 1,96 ms 1 ms
[0080] These results are obtained by simulating 10,000 periods of 30 seconds with different periodicities for the two key fobs. Each time, the difference between the first period value and the second period value is greater than or equal to the duration of a UWB location. Indeed, the second key fob 802 has a periodicity equal to that of the first key fob 801, to which has been added the duration of a location (which is 22 ms in this example). The figures show that, in each situation, the method thus makes it possible to obtain, for these two key fobs 801 and 802, a low percentage of times where more than one second has elapsed between two locations, but this is true when the system also performs other locations in parallel with different third-party devices. In particular, this percentage is always less than 2% when the periodicity of the key fobs 801 and 802 is less than 332. This means that the key fobs 801 and 802 almost never lose more than two successive locations. The method therefore makes it possible to locate the key fobs 801 and 802 with sensitivity and precision in each situation.
[0081] Figure 13 illustrates an example of a vehicle system 10. The system 10 is configured to implement the planning process. In this example, the system includes several secondary UWB sensors (or anchors) 11 connected to a private CAN (Controller Area Network) 12. The secondary UWB sensors 11 are internal to the vehicle. The system also includes a primary sensor (or anchor) 13, which is a master unit for the system. Each UWB sensor includes means for transmitting and receiving UWB exchanges (such as one or more transmitting and / or receiving antennas for such UWB exchanges), with wearable identifiers, for example, to perform UWB location tracking of these wearable identifiers. The system also includes an NFC reader 14. The system supports Bluetooth technology. The primary anchor 13 and the NFC reader 14 are also connected to the system's network 12.
[0082] Figure 14 illustrates an example of a portable identifier 310. The portable identifier 310 is a vehicle remote key housing. Such a vehicle remote key housing may include a protective case enclosing the key housing components. The protective case may be made of plastic, metal, and / or rubberized plastic. The key housing 310 may include a logo, for example, made of metal. The logo may be arranged on the outer casing of the protective case, and / or the logo may represent a manufacturer's brand. Such a key housing may also include, inside the protective case, a metal insert that allows the vehicle to be opened and / or started manually by inserting and manipulating the insert into a respective lock on the vehicle.
[0083] The handheld identifier 310 includes a BLE component 312, configured to perform BLE exchanges with a vehicle, and comprising, for example, a microprocessor. The handheld identifier 310 also includes an antenna 316 connected to the BLE component 312. The antenna 316 is configured to transmit or receive BLE signals. The microprocessor of the BLE component 312 may have in memory a computer program enabling BLE communications and performing various Specific features. The 310 handheld identifier also includes a 311 UWB component for UWB communication with a vehicle. The 310 handheld identifier also includes a 313 battery.
Claims
Demands
1. A method for using a vehicle system comprising one or more UWB anchors, the UWB system having recorded a plurality of portable identifiers, the method comprising: • a detection (S 10) of a first portable identifier around the UWB system; • an implementation (S20) of periodic UWB locations with the first portable identifier, the UWB locations with the first identifier being spaced according to a first period value; • a detection (S30) of a second portable identifier around the UWB system; • a calculation (S40) of a second period value, the difference between the first period value and the second period value being greater than or equal to the duration of a UWB location; • an implementation (S50) of periodic UWB locations with the second portable identifier, the UWB locations with the second identifier being spaced according to the second calculated period value.
2. A method according to claim 1, wherein the first and second period values have a number of common factors less than or equal to a predetermined threshold, for example a threshold equal to 0
3. <1 Method according to claim 2, wherein the first and second period values are relatively prime numbers.
4. A method according to any one of the preceding claims, wherein the first and / or second period value is a prime number.
5. A method according to any one of the preceding claims, wherein the first period value is equal to the result of the product of a multiplier coefficient and a predetermined minimum duration, the second period value not being divisible by the predetermined minimum duration.
6. A method according to any one of the preceding claims, the method further comprising: • detection of a third portable identifier; • calculation of a third period value, the difference between the second period value and the third period value being greater than or equal to the duration of each UWB location, the first, second and third values forming an ordered sequence of numbers; • realization of periodic UWB locations with the third portable identifier, the UWB locations with the third identifier being spaced according to the calculated third period value.
7. A method according to claim 6, wherein the first, second and third period values are numbers that are pairwise relatively prime.
8. Vehicle system comprising one or more UWB anchors and configured for use according to the method of any one of claims 1 to 7.
9. A computer program comprising program code instructions for carrying out the method according to any one of claims 1 to 7, when said program is executed by a processor.
10. Computer-readable storage medium on which the computer program according to claim 9 is recorded.