METHOD AND SYSTEM FOR LOCALIZING A MOBILE DEVICE IN RELATION TO A VEHICLE

Abstract

A method for localizing a mobile device in relation to a vehicle, comprising the following steps: generating a modulated signal from a carrier wave and a baseband signal, wherein the modulated signal is a mechanical wave, the carrier wave has an average carrier frequency, and the baseband signal has an average baseband frequency that is lower than the average carrier frequency; causing the modulated signal to be transmitted by at least two loudspeakers located on the vehicle, wherein the at least two loudspeakers are spaced apart by less than half the wavelength of the average baseband frequency; causing the modulated signal transmitted by the loudspeakers to be received by one or more microphones located on the mobile device via a plurality of localization paths;Demodulating the modulated signal received at the microphone(s) for each of the multiple localization paths to obtain a multiple of demodulated signals; and processing the multiple of demodulated signals to determine the location of the mobile device in relation to the vehicle.

Description

The present invention generally relates to the localization of a mobile device in relation to a vehicle, for example when a user carrying the mobile device approaches the vehicle in a parking lot or parking facility with a number of other vehicles. For many existing vehicles, a user can control certain vehicle functions using a mobile device, such as a smartphone or key fob. For example, it is known that a user can activate an app on a smartphone or key fob to open a vehicle door or start the vehicle remotely. For some applications, such as those where the vehicle uses the approaching user's direction of arrival (DOA) to activate a vehicle function, it may be necessary to determine the location of the mobile device relative to the vehicle. This is sometimes referred to as "localization." Low-frequency waves can be used to accurately determine the location of the approaching mobile device. However, low-frequency waves are generally audible to humans and therefore disruptive. High-frequency waves, on the other hand, are typically inaudible to humans but can introduce some ambiguity regarding the location of the mobile device, especially if the speakers / microphones involved are not positioned close enough together. The method and system disclosed herein addresses these problems. US 2018 / 0 252 796 A1 describes a system comprising a plurality of transmitters, each transmitter configured to emit an ultrasonic signal, and wherein at least one ultrasonic signal is a modulated ultrasonic signal. The system further comprises a mobile device including a processor, a receiver, and instructions stored in non-volatile memory such that, when executed by the processor, the instructions cause the mobile device to receive the ultrasonic signal, calculate a position of the mobile device based on one or more properties of the ultrasonic signals, and demodulate the modulated ultrasonic signal to obtain an information data stream. It can be considered a task to improve the localization of a mobile device in relation to a vehicle. This problem is solved using the subject matter of claims 1 and 11. According to the invention, a method for localizing a mobile device in relation to a vehicle is provided, the method comprising the following steps: generating a modulated signal from a carrier wave and a baseband signal, wherein the modulated signal is a mechanical wave, the carrier wave having an average carrier frequency and the baseband signal having an average baseband frequency that is lower than the average carrier frequency; transmitting the modulated signal from at least two loudspeakers on the vehicle, the at least two loudspeakers being spaced apart from each other by less than half the wavelength of the average baseband frequency; causing the modulated signal transmitted by the loudspeakers to be received at one or more microphones located on the mobile device via a plurality of localization paths;Demodulating the modulated signal received at the microphone(s) for each of the multiple localization paths to obtain a multiple of demodulated signals; and processing the multiple of demodulated signals to determine the location of the mobile device relative to the vehicle. According to the invention, a localization system for a vehicle-mounted device is provided, comprising: two or more mechanical shaft input / output (I / O) devices installed in a vehicle; an electronic control unit (ECU) installed in the vehicle and communicatively coupled to the two or more mechanical shaft I / O devices, the ECU comprising a processor and a memory for storing computer instructions; wherein the computer instructions, when executed by the processor of the ECU in conjunction with computer instructions stored on a vehicle-mounted device, cause the localization system for a vehicle-mounted device to either: transmit a modulated signal using the two or more mechanical shaft I / O devices installed on the vehicle via a plurality of localization paths,wherein the transmitted modulated signal is generated from a carrier wave and a baseband signal and is a mechanical wave, wherein the carrier wave has an average carrier frequency and the baseband signal has an average baseband frequency that is lower than the average carrier frequency; or receiving a modulated signal at the two or more mechanical wave I / O devices installed on the vehicle via a plurality of localization paths, wherein the received modulated signal was generated from a carrier wave and a baseband signal and is a mechanical wave, wherein the carrier wave has an average carrier frequency and the baseband signal has an average baseband frequency that is lower than the average carrier frequency.and wherein the localization system for a vehicle-mounted device demodulates the modulated signal for each of the plurality of localization paths to obtain a plurality of demodulated signals, and then processes the plurality of demodulated signals to determine a location of a mobile device in relation to the vehicle, wherein the at least two wave input / output (I / O) devices are spaced apart by less than half the wavelength of the average baseband frequency. One or more embodiments of the invention are described below in conjunction with the accompanying drawings, wherein identical designations denote identical elements, and wherein the following applies: Fig. 1 is a schematic block diagram of an embodiment of a localization system for vehicle-mounted devices; Fig. 2 is a schematic block diagram of another embodiment of the localization system for vehicle-mounted devices; Fig. 3A is a flowchart illustrating an embodiment of a section of a method for localizing a mobile device in relation to a vehicle, in particular the steps for generating and transmitting a modulated signal; Fig. 3B is a flowchart illustrating an embodiment of another section of a method for localizing a mobile device in relation to a vehicle, in particular the steps for receiving and demodulating the modulated signal; Fig.Figure 4 is a schematic block diagram of a communication system that can be used to carry out one or more embodiments of the method described herein; and Figure 5 is a flowchart that represents an embodiment of an optional safety procedure that can be used in conjunction with the method of Figures 2a and 2b. The system and method described herein provide for the localization of a mobile device relative to a vehicle using mechanical waves and modulation techniques. In one example, a high-frequency carrier wave, generally inaudible to humans, is modulated with a low-frequency baseband signal to produce a modulated signal. The modulated signal is a mechanical or pressure wave, as opposed to an electromagnetic (EM) wave, which is generated or transmitted by one or more loudspeakers and received by one or more microphones. The term "localization path," as used herein, refers to the path traveled by a mechanical wave from a loudspeaker to a microphone. The loudspeakers are part of the vehicle, while the microphone(s) are mounted on the mobile device. There are at least two individual loudspeakers and multiple microphones, while other embodiments include multiple loudspeakers and a single microphone, or even multiple loudspeakers and multiple microphones. As long as multiple localization paths are established, the method and system can use any suitable combination of loudspeaker(s) and microphone(s) to transmit, receive, and process mechanical waves traveling along different localization paths to determine the relative position of the mobile device with respect to the vehicle.Although the following description is given as an example, and there is a single loudspeaker on the mobile device and several microphones on the vehicle, it should be noted that this description serves only to describe the localization paths, but the invention relates to at least two loudspeakers on the vehicle and one or more microphones on the mobile device. The audible frequency range for most people lies between approximately 20 Hz and 19 kHz, although this can vary due to factors such as a person's age. The present method and system uses a high-frequency carrier wave, such as one with a frequency equal to or greater than 15 kHz, so that the resulting modulated signal is generally inaudible or otherwise imperceptible to most people in the immediate vicinity. However, to achieve a desirable level of localization accuracy, the microphones mounted on the vehicle must be spaced less than half the wavelength (1 / 2 λ) apart. By modulating the high-frequency carrier wave with a low-frequency baseband signal, such as one with a frequency of less than or equal to 500 Hz, the half-wavelength spacing requirement will be significantly easier to meet.For illustrative purposes, it is assumed that the speed of sound in air is typically about 340 m / s (these waves are mechanical waves). Since the wavelength of a high-frequency carrier wave with a frequency of 19 kHz, for example, is about 0.018 m, the microphones on the vehicle would need to be less than about 0.009 m (0.9 cm) apart to meet the half-wavelength spacing requirement; such tight design constraints would be extremely difficult to achieve economically for most vehicle-mounted microphones. Under the same assumptions, the wavelength of a low-frequency baseband signal with a frequency of 500 Hz is about 0.68 m, resulting in a much more manageable 0.34 m (34 cm) threshold to meet the half-wavelength spacing requirement.In this way, the present method and system combines the inaudible advantages of the high-frequency carrier wave with the improved localization accuracy of the low-frequency baseband signal to generate a modulated signal for determining the position of the mobile device in relation to the vehicle. Figures 1 and 2 illustrate two possible embodiments of a localization system for vehicle-mounted devices 10, 10' that can be used to implement the disclosed method. While the approach and methodology described herein are explained with respect to systems 10, 10', a person skilled in the art will recognize that these systems are only two examples, and in many respects the schematic block diagrams in these figures serve to simplify the explanation. Other configurations and embodiments can certainly be used instead, since the vehicle-mounted device localization systems and methods described herein represent only some of the possibilities. The vehicle-mounted device localization system 10 of Figure 1 and the vehicle-mounted device localization system 10' of Figure 2 are examples of the methods used to implement the disclosed method.2 are similar, except that system 10 includes mechanical shaft input / output devices (I / O devices) installed on peripheral sections of the vehicle 12, while system 10' includes mechanical shaft I / O devices installed within a single mechanical shaft I / O array module 22 located at a central point of the vehicle 12. The localization system for vehicle-mounted devices 10, 10' can use various combinations of devices, hardware, software, etc., on both a vehicle 12 and a mobile device 30 to perform the procedure described herein. According to one example, the system 10 includes an electronic control unit (ECU) 14, a wireless communication module (WCM) 16, a vehicle system module (VSM) 18, vehicle-mounted mechanical shaft input / output (I / O) devices 20a-20d, a mechanical shaft I / O device 32 that is part of the mobile device, and a wireless communication module (WCM) 34 that is part of the mobile device.The VSM 18 is described herein as a door locking actuator that can be operated between a locked and an unlocked state; however, the VSM 18 may include a variety of other VSMs that can interact with the system 10 and are not limited to door locking actuators. ECU 14 can be coupled to and interact with any number of devices or components located throughout the vehicle, including the various mechanical wave I / O devices 20a-20d. As discussed in more detail below, each of the mechanical wave I / O devices 20a-20d includes a microphone, a speaker, or both. ECU 14 can communicate with the mechanical wave I / O devices 20a-20d via any suitable hardwired or wireless connection (e.g., a vehicle bus, a short-range wireless communication (SRWC) network, etc.). According to one embodiment, wherein the mechanical wave I / O devices 20a-20d are microphones, when a modulated signal is picked up by the mobile device and received by the microphones, corresponding input data representing the modulated signal can be sent from the various microphones to the ECU 14.In another embodiment, in which the mechanical wave I / O devices 20a-20d are loudspeakers, the ECU 14 can send output data containing instructions that direct the loudspeakers to transmit or otherwise generate corresponding mechanical waves. In this way, the ECU 14 can be used to receive and process input data from microphones 20a-20d, to transmit output data in the form of modulated signal instructions to loudspeakers 20a-20d, or, depending on the arrangement, to do both. As used herein, the term "transmit / send" and its other verb forms, when used in relation to a mechanical wave or a mechanical wave I / O device, refers to the propagation of a mechanical wave through a medium, such as the atmosphere surrounding the vehicle. The ECU 14 can incorporate any suitable combination of hardware and / or software components, including a processor and memory. The processor can be any type of device capable of processing electronic instructions, including microprocessors, microcontrollers, host processors, control units, vehicle communication processors, general-purpose processing units (GPUs), accelerometers, FPGAs (field-programmable gate arrays), and application-specific integrated circuits (ASICs), to name just a few. It can be a processor specifically designed for the ECU 14 or it can be shared with other vehicle systems, devices, components, etc. The processor can execute various types of electronic instructions, such as software and / or firmware programs stored in the ECU 14's memory, capable of operating the ECU through a wide variety of functions.The memory of the ECU 14 can include a non-volatile, computer-readable medium; this includes various types of RAM (random access memory, including various types of dynamic RAM (DRAM) and static RAM (SRAM)), read-only memory (ROM), solid-state drives (SSDs) (including other solid-state storage devices, such as semiconductor hybrid drives (SSHDs)), hard disk drives (HDDs), magnetic or optical floppy disk drives, or other suitable computer media that electronically store information. In one example, the processor of the ECU 14 executes programs or processes data, and the memory of the ECU stores programs or other data to enable the execution or support of at least part of the present procedure. The WCM 16 is a wireless communication module that enables the vehicle to communicate with a variety of other devices, including the mobile device 30, and is coupled to the ECU 14, VSM 18, and / or any number of other devices in the vehicle. Unlike the mechanical wave I / O devices 20a-20d, the WCM 16 primarily transmits and receives wireless signals as electromagnetic waves and can do so in the form of short-range wireless communication (e.g., Bluetooth™, Wi-Fi™, etc.) and / or long-range wireless communication (e.g., cellular carriers, telematics communication, etc.). In one embodiment, the WCM 16 includes a short-range cellular communication (SRWC) circuit adapted for Bluetooth™, other IEEE 802.15 communication, Wi-Fi™, other IEEE 802.11 communication, or other similar SRWC communication protocols.In another embodiment, the WCM 16 includes a telematics unit capable of communicating with a mobile, vehicle-to-vehicle, or other cellular network. The vehicle 12 can include multiple WCMs 16 (although only one is shown), such as both an SRWC module and a telematics unit. Although the WCM 16 is shown and described as separate from the ECU 14, in other embodiments the WCM can be integrated with the ECU 14 into a single module. For example, the ECU 14 can include a first WCM 16 (e.g., an SRWC module), and the vehicle 12 can include a separate WCM 16 (e.g., a telematics unit). Mechanical wave I / O devices 20a-d are devices or components that can receive mechanical waves (e.g., microphones) and / or transmit mechanical waves (e.g., loudspeakers). Although four devices 20a-d are shown in Fig. 1, the vehicle 12 can include any number of mechanical wave I / O devices, and in some embodiments, the vehicle includes more or fewer than four such devices. As mentioned above, it is possible that the mobile device 30 includes a mechanical wave I / O device in the form of a loudspeaker and the vehicle 12 includes mechanical wave I / O devices in the form of microphones, or vice versa. Likewise, it is possible that the mobile device 30 includes a single mechanical wave I / O device, while the vehicle 12 includes several mechanical wave I / O devices, or vice versa.As long as multiple localization paths are established between the mobile device 30 and the vehicle 12, any number of combinations of mechanical shaft I / O devices can be used. In the embodiment in which one or more of the mechanical wave I / O devices 20a-d are microphones, mechanical waves are received by the microphone through the atmosphere and converted into electronic signals, which can then be sent as input data to the ECU 14. The microphones can be any suitable type of microphone, including, for example, a dynamic microphone, which uses a diaphragm to detect mechanical waves and moves a magnet to generate electrical signals representative of the mechanical wave. Other microphones can also be used, such as condenser microphones and piezoelectric microphones. The microphones can be configured omnidirectionally, unidirectionally, cardioidally, bidirectionally, shock-shaped, or otherwise.The microphone can include a suitable circuit for scanning or digitizing the mechanical shaft before sending it to the ECU 14, or this scanning can be performed at the ECU itself. Thus, the input data sent from the microphones to the ECU 14 can be in the form of analog or digital signals. In the embodiment in which one or more of the mechanical wave I / O devices 20a-d are loudspeakers, the ECU 14 sends electronic signals in the form of output data to the loudspeakers, causing the loudspeakers to convert the output data into mechanical waves and transmit them through the atmosphere. Any suitable type of loudspeaker can be used, including various loudspeakers. For example, a dynamic loudspeaker can be used, in which a diaphragm moves in response to an electrical signal to generate a corresponding mechanical wave, such as a modulated signal, which will be explained below. The loudspeakers can include any number or type of drivers, such as tweeters, midrange drivers, and / or woofers.The loudspeakers can generate mechanical or pressure waves according to information received from the ECU 14, such as modulation information or parameters, which are explained in more detail below. The output data sent from the ECU 14 to the loudspeakers can be in the form of analog or digital signals. The collection of mechanical wave I / O devices 20a-20d is referred to as a mechanical wave I / O device array (which may be a microphone array or a loudspeaker array), and the arrangement, orientation, spacing, and / or orientation of these arrays can vary. In the example of Fig. 1, the mechanical wave I / O devices 20a-d are part of an array distributed around the perimeter of the vehicle 12 (e.g., within the front and rear bumpers near the corners of the vehicle). In the example of Fig. 2, however, the mechanical wave I / O devices 20a-d are more tightly grouped in an array that is packaged in a single module or assembly and is located toward a center of the vehicle 12. These are, of course, only two possibilities.The configuration of the mechanical shaft I / O device assembly, including the distances and angles between the individual devices 20a-d, can be used by the vehicle-mobile device localization method to determine the position of the mobile device relative to the vehicle. For example, by knowing the configuration and spacing of the devices in the mechanical shaft I / O device assembly, the method can use the relative phases of the various mechanical shafts traveling along different localization paths to determine the location of the mobile device relative to the vehicle. The arrangement, orientation, spacing, and / or orientation of the mechanical shaft I / O device assembly can be represented by configuration data stored in the memory of the ECU 14 (or another VSM of the vehicle 12).In particular, the maximum distance between any two of the individual mechanical wave I / O devices 20a-d (called the maximum I / O device spacing) can be used to select a suitable baseband frequency and should be less than half the wavelength of the baseband frequency; thus, the maximum I / O device spacing and the requirement of half a wavelength spacing are related. The maximum distance between the I / O devices can be part of the configuration data and can be stored in the memory of the ECU 14, in the memory of the mobile device 30, or in both. The mobile device 30 is an electronic device, such as a smartphone or a key fob, that includes a mechanical wave I / O device 32 and a wireless communication module 34. As previously explained, the mechanical wave I / O device 32 can include a loudspeaker, a microphone, or both, as long as at least two separate localization paths are established with the vehicle. For example, in the embodiments illustrated in Figures 1 and 2, the mobile device 30 includes a single loudspeaker 32, and the vehicle 12 includes four microphones 20a-d. The single loudspeaker 32 can transmit a modulated signal in the form of mechanical waves, which are received at each of the microphones 20a-d via four separate localization paths 24a-d, each localization path 24a-d being located between the loudspeaker 32 and one of the microphones 20a-d.The foregoing explanation of the requirement for half the wavelength spacing and / or the maximum spacing of the I / O devices would also apply to the mobile device 30, provided that the device includes several mechanical shaft I / O devices 32. An embodiment of the present method is shown in Figures 3A and 3B, wherein Figure 3A describes the steps of a method 200 for generating and transmitting modulated signals and Figure 3B describes the steps of a method 300 for receiving and processing such signals in order to locate a mobile device in relation to a vehicle. The combinations of steps 200 and 300 are preferably used together in the present method. Starting with step 210, the procedure receives an indication or otherwise detects a condition or event that signals it to begin transmitting a modulated signal (i.e., to start the procedure). In an example, step 210 detects that a user with a mobile device 30 is nearby, perhaps by determining that the vehicle 12 and the mobile device 30 recently paired wirelessly, for example, via an SRWC protocol (such as Bluetooth™). In an example where the mobile device 30 is used as a key to access or control the vehicle 12, the WCM 34 can establish an SRWC connection with the WCM 16 and exchange authentication information between them (such as a virtual vehicle key).Once authenticated, the vehicle 12 can inform the mobile device 30 that it has been authenticated, which can serve as an indication of the start of the transmission of a modulated signal; in other words, an indication that the localization process of the vehicle's mobile device can begin. It is possible that indications other than the pairing of vehicle-to-mobile devices are used to initiate the localization of the vehicle-to-mobile devices. Procedure 200 continues with steps 220 and 230. Steps 220 and 230 are described herein as being performed simultaneously or nearly simultaneously. However, in other embodiments, these steps may be performed serially, such as the first step 220 followed by step 230, or step 230 followed by step 220. In step 220, carrier wave information is obtained and shaped so that the modulated signal is inaudible to most people. In one embodiment, the carrier wave information includes a carrier wave frequency, a carrier wave amplitude, a carrier wave power, and / or other parameters of the carrier wave to be used. If the frequency of the carrier wave, which is a mechanical or sound wave, is equal to or greater than approximately 19 kHz, the wave is generally inaudible to humans. And in at least some embodiments, the average carrier frequency is at least thirty-eight times greater than the average baseband frequency.In one embodiment, the carrier wave information is stored in and retrieved from a memory on the mobile device 30, but in other embodiments, the carrier wave information changes and is provided via the WCM 34 from the vehicle 12, a remote facility and / or another source as part of an enhanced safety feature, as described below. In step 230, baseband signal information is obtained and configured so that the modulated signal enables precise localization. In one embodiment, the baseband signal information includes a baseband signal frequency, a baseband signal amplitude, a baseband signal, baseband modulation schemes, baseband center frequencies, and / or other parameters of the baseband signal to be used. If the frequency of the baseband signal is less than or equal to 500 Hz (e.g., between 100 Hz and 500 Hz) and the corresponding half-wavelength spacing requirement is met, the method is generally able to accurately determine the location of the mobile device 30 relative to the vehicle 12. As explained below, the carrier wave and / or the baseband signal can have a single frequency (single tone) or multiple frequencies (e.g., multi-tone, narrowband, broadband, etc.).The terms "average carrier frequency" and "average baseband frequency," as used herein, mean the average frequencies of the carrier wave and the baseband signal over a given signal transmission. Therefore, the condition that a baseband signal has an average baseband frequency lower than an average carrier frequency means that, over the course of a given signal transmission, the average frequency of the baseband signal must be lower than the average frequency of the carrier wave. It is possible for the baseband signal to momentarily have a baseband frequency higher than a corresponding carrier frequency and still satisfy the previous condition, as long as the average frequency of the baseband signal remains lower than the average frequency of the carrier wave over the given signal transmission.As with the carrier wave information, the baseband signal information can be stored locally in the memory of the mobile device 30, or it can be obtained wirelessly via the WCM 34 from the vehicle 12, a remote facility and / or another source. The baseband signal frequency can be selected based on the maximum spacing of the I / O devices. For example, the baseband signal frequency fBaus can be selected to satisfy the following equations: where v is the speed of sound (or mechanical waves) in the atmosphere (or another medium), λB is the baseband signal length, and dmax is the maximum spacing of the I / O devices. As mentioned above, in one embodiment using a single loudspeaker and a plurality of microphones, the spacing dmax can be any two microphones at a time (e.g., microphones 20a and 20d in Figures 1 and 2). In another embodiment using a single microphone and a plurality of loudspeakers, the spacing dmax can be any two loudspeakers at a time.And in embodiments where a plurality of microphones and a plurality of loudspeakers are used, the distance dmax can be the greater of the maximum distance between any two microphones and the maximum distance between any two loudspeakers. At least in some embodiments, as estimated by those skilled in the art, the use of this relationship between the maximum distance of the I / O devices dmax and the baseband signal length allows the derivation of an accurate direction of arrival (DOA). The present method can employ various modulation techniques to generate the modulated signal. For example, the carrier wave can be modulated with a baseband signal (BS) that has only a single baseband frequency (i.e., a single frequency or monotonous baseband signal). In other cases, such as when additional safety measures are required or when a significant amount of background noise is present, the carrier wave can be modulated with baseband signals that have different or changing baseband frequencies (i.e., a multi-frequency or multi-tone baseband signal). In a modulation scheme using multi-frequency or tone baseband signals, the carrier wave is modulated with a rotating set of baseband signals that change according to a modulation scheme known to both the mobile device 30 and the vehicle 12.For example, the carrier wave can be modulated with a first baseband signal (e.g., a single-tone signal BS-single) for a specific period, then with a second baseband signal (e.g., a narrowband baseband signal BS-narrow) for a period, and then with a third baseband signal (e.g., a broadband baseband signal BS-wide) for a period before switching back to the first baseband signal and repeating the cycle. In such embodiments, a remote device and / or another source can provide both the mobile device 30 and the vehicle 12 with carrier wave information and / or baseband signal information in advance, so that a mutually known and agreed-upon modulation scheme can be established. For the single-tone baseband signal BS-single, a single baseband frequency fBin can be used to record the baseband signal information.For multi-tone baseband signals, such as the narrowband baseband signal BS-narrow and the wideband baseband signal BS-wide, parameters such as bandwidths, center frequencies, passwords, etc., can be included in the carrier wave and / or baseband signal information and sent to WCMs 16 and / or 34. After the carrier wave information (step 220) and the baseband signal information (step 230) have been received, procedure 200 continues with step 240. In step 240, a modulated signal is generated based on a baseband signal and a carrier wave. In one embodiment, the baseband signal is modulated over the carrier wave using amplitude modulation; however, in other embodiments, other modulation methods can be used. The carrier wave can be defined by the following carrier wave equation: where C(t) is the carrier wave equation, fc is the carrier frequency, and t is time. In at least some embodiments, the carrier frequency fc is specified by the carrier wave information as described above. In one embodiment, such as when using a single-tone baseband signal, the following baseband equation can be used: where B(t) is the baseband signal equation, fB is the baseband frequency (or modulation frequency), and t is time. Of course, other baseband equations can also be used, such as when multi-tone signals (e.g., multi-tone ...B. narrowband, broadband) can be used for modulation. In one embodiment, when using multiple baseband signals (or signal types), the baseband signals can be modulated via a common carrier wave and / or using a common carrier frequency. Continuing the previous example of the carrier wave equation C(t) and the baseband equation B(t), a modulated signal equation can be obtained that represents a modulated signal MS generated by applying the baseband signal (or wave equation) to the carrier wave: where X(t) is the modulated signal equation, A is the amplitude of the carrier wave, and Ma is the amplitude of the baseband signal. The modulation parameters A and Ma can be obtained, for example, in steps 220 and / or 230. According to the example where a loudspeaker 32 on the mobile device 30 is used to transmit a modulated signal to the vehicle 12, electrical signals in the form of output data representative of the desired modulated signal can be provided to the loudspeaker by the mobile device. Although amplitude modulation with a single-tone baseband signal has been described above, various other modulation techniques with different baseband signals can be used. For example, amplitude modulation with multiple frequency baseband signals, frequency modulation with a single frequency baseband signal, or frequency modulation with multiple frequency baseband signals could be used, to name just a few possibilities. In other embodiments, phase modulation or other modulation techniques can be used. The procedure then proceeds to step 250. In step 250, the modulated signal is transmitted through the surrounding atmosphere via one or more loudspeakers. As in the previous example, output data in the form of electronic signals is sent to the loudspeaker 32 of the mobile device 30, and the loudspeaker then generates a mechanical or sound wave corresponding to the modulation signal MS. The mechanical wave can be transmitted by the loudspeaker 32 and received at the microphones 20a-d of the vehicle 12 via the four localization paths 24a-d. The modulated signal can be transmitted for a specific duration and / or at a specific interval. For example, the modulated signal can be transmitted by the loudspeaker 32 for an initial interval before waiting for a second interval, after which the modulated signal can be transmitted again for the first interval. Alternatively, various other techniques and schemes can be used. In embodiments using multiple frequency baseband signals (e.g., the rotating example above), steps 230-250 can be performed sequentially for each of the different baseband signals. For example, three sequentially generated modulated signals can be produced and transmitted, such as a first modulated signal based on a single-tone baseband signal RS-single (referred to as a single-tone modulated signal MS-single), a second modulated signal based on a narrowband baseband signal BS-narrow (referred to as a narrowband modulated signal MS-narrow), and a third modulated signal based on a broadband signal BS-wide (referred to as a broadband modulated signal MS-wide). In this case, the multiply modulated signals can be transmitted serially by the loudspeaker.For example, the single-tone modulated signal MS-single can be transmitted first for 0.1 seconds, then the narrowband modulated signal MS-narrow for 0.1 seconds, and then the broadband modulated signal MS-wide for 0.1 seconds. This process can then be repeated several times or until a feedback signal is received from vehicle 12 (or another receiving device) (e.g., via WCM 16 and / or 34). With reference to Fig. 3B, part 300 of the method is shown, which is directed towards receiving a modulated signal and using a mobile device in relation to a vehicle. The method 300 is preferably carried out according to the method 200. In one embodiment, the method 300 is carried out on the vehicle 12 and in particular by the ECU 14 and / or the mechanical wave I / O devices 20a-d (e.g. microphones located on the vehicle). In step 310, the modulated signal is received at a plurality of microphones. As explained above, the modulated signal can be transmitted via mechanical waves from the loudspeaker 32 of the mobile device 30. The modulated signal MS is then received at the microphones 20a-d of the vehicle 12 via a plurality of localization paths 24a-d, as shown in Fig. 1 and Fig. 2. Thus, a modulated signal MS,n is received for each localization path n. For example, microphone 20a receives a modulated signal MS,1 corresponding to localization path 24a, microphone 20b receives a modulated signal MS,2 corresponding to localization path 24b, microphone 20c receives a modulated signal MS,3 corresponding to localization path 24c, and microphone 20d receives a modulated signal MS,4 corresponding to localization path 24d.The microphones 20a-d can convert the acoustic or mechanical energy of the modulation signals into corresponding input data in the form of electrical signals that can be sent to ECU 14 to determine the position of the mobile device in relation to the vehicle. In step 320, the received modulated signals are demodulated. For example, the four modulated signals MS,1 to MS,4 are each demodulated to obtain demodulated signals DS,1 to DS,4. Various demodulation techniques can be used. The demodulated signals DS,1 to DS,4 represent the baseband signal BS as observed at each of the microphones 20a-d. In one embodiment, demodulation can be performed at each individual microphone 20a-d. In another embodiment, the received modulated signals MS,1 to MS,4 are sent to the ECU 14, which can then demodulate the signals. Certain characteristics of the demodulated signals, such as the phase or amplitude of the demodulated signal (or wave), can be identified. For example, a time value (e.g.,timestamps) and / or the amplitude or phase of each of the demodulated signals can be obtained by demodulating the received modulated signal along each localization path 24a-d. In step 330, which is optional, the demodulated signals can then be stored in memory. In one embodiment, the demodulated signals DS,1 to DS,4 are stored in the memory of the ECU 14. In other embodiments, a different storage device of the vehicle 12 can be used. The procedure 300 can then proceed to step 340. In step 340, the demodulated signals are processed to determine the position of the mobile device relative to the vehicle. In one embodiment, determining the location of the mobile device involves determining the direction of arrival (DOA) of the mobile device 30 (or loudspeaker 32) relative to the vehicle 12 (or microphone array 22). Various processing techniques can be used to determine a DOA or other location features relative to the signal. For example, the phase and / or amplitude of each of the demodulated signals is an indicator of the length of that particular localization path (i.e., the phase of the signal when received at a microphone indicates the distance between the loudspeaker and that particular microphone within half a wavelength; hence the half-wavelength requirement).Knowing the relative length of each of the localization paths, as well as the configuration of the mechanical wave I / O device arrangement (i.e., the position of each of the microphones relative to each other), allows the position of the mobile device relative to the vehicle to be determined. In one particular embodiment, a MUSIC (Multiple Signal Classification) technique is applied to the demodulated signals DS,1 to DS,4 to assist in determining the DOA, as understood by those skilled in the art. Method 300 then proceeds to step 350. Step 350 determines whether the determination made in step 340 should be accepted. In one embodiment, the method can apply an acceptance threshold to the MUSIC value, although other acceptance or confirmation techniques can be used instead. If it is determined that the determination made in step 340 is accepted, the method proceeds to step 360; otherwise, the method returns to step 340. If the results are not acceptable, the location of the mobile device relative to the vehicle can be calculated using a next set of demodulated signals. In one embodiment, a next set of demodulated single-tone signals DS,1-single to DS,4-single can be used. As mentioned previously, in other embodiments, numerous different baseband signals and / or modulation schemes can be used to modulate the carrier wave, including single-tone baseband signals, narrowband baseband signals, and wideband baseband signals. Step 340 can be performed for the demodulated single-tone signals DS,1-single to DS,4-single, and if the results are found to be unacceptable in step 350, step 340 can be performed again using the narrowband demodulated signals DS,1-narrow to DS,4-narrow.Subsequently, in step 350, it can be determined whether the location determination based on the narrowband demodulated signals DS,1-narrow to DS,4-narrow is acceptable. If not, step 340 can be performed using the broadband demodulated signals DS,1-wide to DS,4-wide. This optional process can be repeated until the results are acceptable. In step 360, a vehicle action or function is performed. In a scenario where it is determined that the mobile device 30 (and thus the user) is approaching the vehicle 12 and is near a specific vehicle door, such as the right rear passenger door, step 360 can unlock and / or open the right rear passenger door. In another embodiment, the method can determine that the mobile device 30 (and thus the user) is near the vehicle's trunk, and in response, step 360 can automatically and predictively unlock and / or open the trunk. For example, the ECU 14 can send commands or other electronic signals to the VSM 18 instructing it to unlock and / or open one or more vehicle doors, trunks, etc.Such a function can be particularly useful in a car-sharing application where a user is searching for an unknown vehicle in a parking lot or facility with a large number of other vehicles (possibly of the same make and model). The procedure helps to locate the user in relation to the vehicle in question and takes some kind of additional action to facilitate the user's identification of the vehicle. In another example, once the mobile device 30 (and thus the user) is in the direction of the vehicle and is considered to have approached it or is near it, the ECU 14 could send commands to a visual and / or audible device on the vehicle (e.g., lights, horn, etc.) and instruct it to inform the user of its immediate proximity.In another embodiment, the ECU 14 can select a specific vehicle action to be executed based on parameters such as user proximity or location. Various other vehicle actions are also possible, as the method is not limited to one or more individuals. In further embodiments, section 200 of the method can be performed by the vehicle 12 and section 300 of the method by the mobile device 30. For example, the mechanical wave I / O devices 20a-d of the vehicle 12 can be loudspeakers, and the mechanical I / O device 32 of the mobile device 30 can be a microphone. In such a case, the vehicle 12 can generate and transmit the modulated signal MS from each of the four loudspeakers. The microphone of the mobile device 30 can then receive each of the signals via a separate localization path 24a-d. The mobile device 30 can then demodulate the signals and perform the other steps of the method 300. In another example, the mobile device 30 can include a plurality of microphones, and the vehicle 12 can include a single loudspeaker to generate a plurality of localization paths.In other embodiments, a large number of loudspeakers and a large number of microphones can be used to establish a large number of communication channels. With reference to Fig. 4, a communication system 100 is shown, which can be used in conjunction with the vehicle-mounted device localization system and the method described above. The communication system 100 includes the vehicle-mounted device localization system 10, a remote device 50, and a mobile communication carrier system 60. The mobile communication carrier system 60 can be one of a variety of mobile communication systems used for long-range radio communication and is shown to include two mobile communication towers 62a, b that can communicate with the vehicle 12 and / or the mobile device 30. The vehicle 12 can optionally include two WCMs 26, 28, and the mobile device can include two WCMs 36, 38 in addition to the mechanical wave I / O devices (i.e., loudspeaker and microphone(s)) described above. The WCMs 26, 36 are short-range wireless communication (SRWC) devices that use electromagnetic signals, as opposed to mechanical or sound waves, to perform various SRWCs, such as those described above. The SRWC device 26 of the vehicle 12 is shown to be contained within the ECU 14; however, the SRWC device 26 may be arranged as part of a separate VSM in other embodiments. The WCMs 28, 38 are long-range radio communication devices and, in at least some embodiments, include a cellular chipset (or other suitable circuitry) for establishing a cellular connection with the cellular carrier system 60. The WCM 28 may, for example, be a vehicle telematics unit. In one embodiment, the mobile device 30 can download and install computer instructions (or an application) that perform at least some of the process steps. With reference to Fig. 5, an embodiment of a method 400 for locating a mobile device in relation to a vehicle is shown. In one embodiment, the method 400 can be performed in response to a carsharing reservation made by a vehicle user. The carsharing reservation can enable the vehicle user to obtain access data (or authentication information) that allows the vehicle user's mobile device 30 to access and / or control the vehicle 12. Other embodiments are certainly possible. In step 410, authentication information and modulation information are transmitted from a remote device to the vehicle. The authentication information may be a virtual vehicle key, user information, and / or other information that can be used to authenticate and / or authorize the vehicle user to access and / or control the vehicle 12. The modulation information may be carrier wave information and / or baseband signal information, as explained above (see steps 220 and 230 of Method 200 (Fig. 3A)). In one embodiment, the authentication information and the modulation information are provided by the remote device 50 to the WCMs 28, 38 on the vehicle and mobile device, respectively.For example, the telematics unit 28 and the WCM 38 of the mobile device can establish connections to a server in the remote facility 50 via a mobile communication carrier system 60. The remote server (i.e., the server in the remote facility 50) can then provide the authentication and modulation information. After being received at the telematics unit 26, the authentication and modulation information can be sent to the ECU 14. Steps 410 and 420 are described herein as being performed concurrently. However, in other embodiments, these steps may be performed sequentially, such as the first step 410 followed by step 420, or step 420 followed by step 410. In step 420, the authentication information and modulation information of the mobile device 30 are provided. In one embodiment, the authentication information and modulation information of the mobile device 30 are provided via a connection to a remote server in the remote facility 50. For example, the authentication information and modulation information of the mobile device are provided via the cellular carrier system 60.In another embodiment, the authentication information can be sent from the remote facility 50 to the mobile device 30, and then the vehicle 12 and the mobile device can establish an SRWC connection (step 430) when the mobile device 30 is authenticated by the vehicle 12 using the authentication information. Afterward, the modulation information can be transmitted to the mobile device 30 using the secure SRWC connection. Conversely, the vehicle 12 can receive only the authentication, while the mobile device 30 receives both the authentication information and the modulation information. Afterward, the mobile device 30 can send the modulation information to the vehicle 12 via the secure SRWC connection. In step 430, the mobile device is authenticated by the vehicle. The authentication information can be used to authenticate the mobile device 30 for access to and / or control of the vehicle 12. In one embodiment, the vehicle 12 can detect the presence of the mobile device 30 using the SRWC device 26, and then the mobile device 30 and the vehicle 12 can establish a secure SRWC connection. After the secure SRWC connection is established, the mobile device 30 can send at least some of the authentication information to the vehicle 12, which can then determine whether the mobile device 30 should be authenticated and / or whether the mobile device 30 is authorized to access and / or control the vehicle. If it is determined that the mobile device will not be authenticated by the vehicle (e.g.,If the mobile device 30 is not authenticated (the mobile device 30 is not authorized), procedure 400 terminates. Otherwise, procedure 400 continues with step 440. In step 440, a localization process is performed for a vehicle-mounted device. In one embodiment, methods 200 and / or 300 can be performed by the vehicle-mounted device localization system 10. For example, in one embodiment, the vehicle-mounted device 30 can transmit a modulated signal via one or more loudspeakers 32 (Figs. 1 and 2), which can then be received by one or more microphones 20a-d (Figs. 1 and 2) of the vehicle 12. The modulated signal can include a carrier frequency of 15 kHz or higher, so that the signal is inaudible to at least some people. Once the vehicle-mounted device 30 is in relation to the vehicle 12, a vehicle action, such as one of those mentioned above, can be performed. Method 400 then terminates.

Claims

A method for localizing a mobile device in relation to a vehicle, comprising the following steps: generating a modulated signal from a carrier wave and a baseband signal, wherein the modulated signal is a mechanical wave, the carrier wave has an average carrier frequency, and the baseband signal has an average baseband frequency that is lower than the average carrier frequency; causing the modulated signal to be transmitted by at least two loudspeakers located on the vehicle, wherein the at least two loudspeakers are spaced apart by less than half the wavelength of the average baseband frequency; causing the modulated signal transmitted by the loudspeakers to be received by one or more microphones located on the mobile device via a plurality of localization paths;Demodulating the modulated signal received at the microphone(s) for each of the multiple localization paths to obtain a multiple of demodulated signals; and processing the multiple of demodulated signals to determine the location of the mobile device in relation to the vehicle. The method of claim 1, wherein the transmitting step further comprises that the modulated signal is transmitted from a single loudspeaker located on the mobile device, and the receiving step further comprises that the modulated signal transmitted from the single loudspeaker on the mobile device is received at a plurality of microphones located on the vehicle. Method according to claim 2, wherein the mobile device is a smartphone with a smartphone speaker and the transmission is initiated by a software application running on the smartphone which instructs the smartphone speaker to transmit the modulated signal to the vehicle. Method according to claim 1, wherein the processing step uses differences in the phase of the plurality of demodulated signals attributable to the different localization paths to determine the location of the mobile device in relation to the vehicle. The method of claim 1, wherein the generation step includes generating a plurality of modulated signals, the plurality of modulated signals having a common carrier frequency and a plurality of different baseband frequencies. Method according to claim 5, wherein the plurality of baseband frequencies includes a single-tone baseband frequency, a narrowband baseband frequency and a broadband baseband frequency. The method of claim 5, wherein the method further comprises rotation through a set of modulation schemes to generate the plurality of modulated signals. The method of claim 7, wherein the method further comprises determining whether the location determined using the demodulated signals corresponding to a first baseband frequency type is to be accepted, and, if determined, not to accept the location determined using the demodulated signals corresponding to the first baseband frequency type, performing the determination step using other demodulated signals corresponding to a second baseband frequency type. The method of claim 1, wherein at least a part of the carrier wave information or baseband signal information, selected from the following list, is wirelessly provided from a remote facility to a mobile device and / or the vehicle: a carrier frequency, a carrier amplitude, a baseband frequency, a narrow baseband range, a wide baseband range, a baseband amplitude or a modulation method. The method of claim 9, wherein the at least one carrier wave information or baseband signal information is wirelessly provided from a remote device to a mobile device and / or the vehicle in response to a car sharing or ride-sharing reservation, and the method further includes authenticating the mobile device on the vehicle by causing authentication information to be transmitted from the mobile device to the vehicle via short-range wireless communication (SRWC). Localization system for a vehicle-mounted device, comprising: two or more mechanical shaft input / output (I / O) devices installed in a vehicle; an electronic control unit (ECU) installed in the vehicle and communicatively coupled to the two or more mechanical shaft I / O devices, the ECU comprising a processor and memory for storing computer instructions; wherein the computer instructions, when executed by the processor of the ECU in conjunction with computer instructions stored on a vehicle-mounted device, cause the vehicle-mounted device localization system to either: transmit a modulated signal using the two or more mechanical shaft I / O devices installed in the vehicle via a plurality of localization paths,wherein the transmitted modulated signal is generated from a carrier wave and a baseband signal and is a mechanical wave, the carrier wave has an average carrier frequency and the baseband signal has an average baseband frequency that is lower than the average carrier frequency; or receiving a modulated signal at the two or more mechanical wave I / O device(s) installed in the vehicle via a plurality of localization paths, wherein the received modulated signal was generated from a carrier wave and a baseband signal and is a mechanical wave, the carrier wave has an average carrier frequency and the baseband signal has an average baseband frequency that is lower than the average carrier frequency, and wherein the localization system for a vehicle-mounted device demodulates the modulated signal for each of the plurality of localization paths,to obtain a multitude of demodulated signals, and then process the multitude of demodulated signals to determine the location of a mobile device relative to the vehicle, wherein the at least two wave input / output (I / O) devices are spaced apart by less than half the wavelength of the average baseband frequency.

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