Patent Publication Number: US-2017361806-A1

Title: Ultrasound assisted location and access control

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. Provisional Application Ser. No. 62/352,339, filed Jun. 20, 2016, the contents of which are incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The subject invention relates to locating objects with respect to a vehicle and, in particular, to a system and method for communicating between a vehicle and a mobile device in order to control an operation at the vehicle based on a location of the mobile device. 
     BACKGROUND 
     A driver performs different actions depending on his or her location with respect to a vehicle. Therefore, knowing the location of the driver can be used to create a more convenient and enjoyable automotive experience. The driver generally carries with him or her various objects that have communication abilities, such as a smartphone or other electronic device. Accordingly, it is desirable to provide a system for determining the location of such objects carried by the driver in order to perform an appropriate operation at the vehicle. 
     SUMMARY OF THE INVENTION 
     In one exemplary embodiment, a system for performing an operation at a vehicle includes a first acoustic transceiver that transmits and receives inaudible acoustic signals; a second acoustic transceiver that is stationary with respect to the vehicle, wherein the second acoustic transceiver transmits and receives inaudible acoustic signals; and a processor configured to: receive an inaudible acoustic signal transmitted between the first acoustic transceiver and the second acoustic transceiver, determine a location of the first acoustic transceiver with respect to the vehicle from the received signal, and perform the operation at the vehicle based on the location of the first acoustic transceiver. 
     The inaudible acoustic signal may be transmitted from the first acoustic transceiver to the second acoustic transceiver, transmitted from the second acoustic transceiver to the first acoustic transceiver, or a signal transmitted from the first acoustic transceiver in response to an inaudible acoustic signal from the second acoustic transceiver. Alternatively, the inaudible acoustic signal may be transmitted from the second acoustic transceiver to the first acoustic transceiver and either the location is determined at the first acoustic transceiver, or the received signal may be forward to the vehicle and the location may be determined at the vehicle. 
     In an embodiment, the second acoustic transceiver includes an array of second acoustic transceivers and the processor triangulates a location of the first acoustic transceiver from a plurality of transmitted and received signals transmitted between the array of second acoustic transceivers and the first acoustic transceiver. In another embodiment, the transceivers of the array of second acoustic transceivers communicate sequentially with the first acoustic transceiver. 
     The first acoustic transceiver may be included in a hand-held mobile device. The mobile device transmits a security code to the vehicle and the processor activates the second transceiver when the security code matches a security code stored at the vehicle. The mobile device transmits the security code using electromagnetic signals. The security code is installed at the mobile device and provided to the vehicle from a remote location. 
     Performing the operation may include, for example, opening a door of the vehicle, starting the vehicle, connecting a phone call to the vehicle, sounding an alarm, calling a separate phone, preventing the vehicle from being locked, and sending an outgoing message to a remote system. 
     In another exemplary embodiment, a method for performing an operation at a vehicle includes: transmitting an inaudible acoustic signal between a first acoustic transceiver and a second acoustic transceiver affixed to the vehicle, determining, at a processor, a location of the first acoustic transceiver with respect to the vehicle from the received signal, and performing the operation at the vehicle based on the location of the first acoustic transceiver with respect to the vehicle. 
     The inaudible acoustic signal may be transmitted from the first acoustic transceiver to the second acoustic transceiver, transmitted from the second acoustic transceiver to the first acoustic transceiver, or a signal transmitted from the first acoustic transceiver in response to an inaudible acoustic signal from the second acoustic transceiver. Alternatively, the inaudible acoustic signal is transmitted from the second acoustic transceiver to the first acoustic transceiver and either the location is determined at the first acoustic transceiver or the received signal is forwarded to the vehicle and the location is determined at the vehicle. 
     In an embodiment, the second acoustic transceiver includes an array of second acoustic transceivers and a location of the first acoustic transceiver is triangulated from a plurality of inaudible acoustic signals transmitted between the array of second acoustic transceivers and the first acoustic transceiver. The transceivers of the array of second acoustic transceivers may communicate sequentially with the first acoustic transceiver. 
     In an embodiment, the first acoustic transceiver is included in a mobile device that is mobile with respect to the vehicle. A security code is transmitted from the mobile device to the vehicle and the second transceiver is activated when the security code matches a security code stored at the vehicle. The mobile device may transmit the security code using electromagnetic signals. The security code may be transmitted to the mobile device from a remote location. 
     The operation to be performed may include, for example, opening a door of the vehicle, starting the vehicle, connecting a phone call to the vehicle, sounding an alarm, calling a phone, preventing the vehicle from being locked, or sending an outgoing message to a remote system. 
     The above features and advantages, and other features and advantages, are readily apparent from the following detailed description when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which: 
         FIG. 1  shows a passive entry passive start (PEPS) system that uses acoustic signals to determine a location of an object with respect to a vehicle and to perform an operation at the vehicle based on the location of the object; 
         FIG. 2  illustrates a communication protocol between a mobile device and a vehicle; and 
         FIG. 3  shows a graph resulting from an experiment showing range determination for a mobile device placed at a selected location with respect to a transceiver using the acoustic signals discussed herein. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
     In accordance with an exemplary embodiment of the invention,  FIG. 1  shows a passive entry passive start (PEPS) system  100  that uses acoustic signals to determine a location of an object with respect to a vehicle and to perform an operation at the vehicle based on the location of the object. As discussed herein, an “acoustic signal” generally refers to an acoustic signal that is in an inaudible frequency range. This frequency range may include frequencies greater than about 16 kiloHertz (kHz). In an embodiment, the acoustic signals of the invention have a frequency that is in the range between 16.5-17 kHz to 18.5-19 kHz. In another embodiment, the acoustic signal can include a signal having a frequency greater than about 20 kHz, or within an ultrasonic frequency range. 
     The system  100  includes a vehicle  102  having a plurality of acoustic transceivers  104   a ,  104   b ,  104   c  and  104   d  located at separate locations around the vehicle  102 . Additional acoustic transceivers  104   e ,  104   f ,  104   g  and  104   h  are also shown. In general, the acoustic transceivers  104   a ,  104   b ,  104   c  and  104   d  are more suitable for communication with an object outside of the vehicle, while acoustic transceivers  104   e ,  104   f ,  104   f  and  104   h  are more suitable for communication with an object inside the vehicle  102 . The number of transceivers shown in  FIG. 1  is just for illustrative purposes only and is not meant to be a limitation of the disclosure. 
     In the illustrative embodiment of  FIG. 1 , acoustic transceiver  104   a  is located at a left front bumper location, acoustic transceiver  104   b  is located at a right front bumper location, acoustic transceiver  104   c  is located at a left rear bumper location and acoustic transceiver  104   d  is located at a right rear bumper location. The acoustic transceivers  104   a ,  104   b ,  104   c  and  104   d  are capable of transmitting and receiving acoustic signals. Furthermore, vehicle  102  includes an electromagnetic transceiver  106  for communicating via electromagnetic waves. In one embodiment, the electromagnetic transceiver  106  transmits and receives signals using a short-range communication protocol, such as Bluetooth. However, other electromagnetic frequency ranges and communication protocols can be used in alternate embodiments. 
     A handheld device or mobile device  108  moves with respect to the vehicle  102  and is generally carried by a passenger or driver of the vehicle  102 . The mobile device  108  can be a smartphone or other mobile device in various embodiments. The mobile device  108  may also be a key fob attached to keys for the vehicle  102 . The mobile device  108  includes an acoustic transceiver  108   a  that transmits and receives acoustic signals  120  and thereby communicates with transceivers  104   a ,  104   b ,  104   c  and  104   d . The mobile device  108  also includes an electromagnetic transceiver  108   b  for transmitting and receiving electromagnetic signals  122  with the electromagnetic transceiver  106  of vehicle  102 . The mobile device  108  may include a processor for operating the acoustic transceiver  108   a  and performing calculations discussed herein. 
     The vehicle  102  includes a control unit  110  for performing various operations disclosed herein. The control unit  110  includes a processor that operates the acoustic transducers  104   a ,  104   b ,  104   c  and  104   d  to communicate with the acoustic transceiver  108   a  through acoustic signals and operates electromagnetic transceiver  106  to communicate with electromagnetic transceiver  108   b  through electromagnetic signals. The processor of control unit  110  also runs programs that determine a location of the mobile device  108  with respect to the vehicle  102  using acoustic signals  120  and/or electromagnetic signals  122  and that perform an operation based on the determined location of the mobile device  108 . 
     To initiate a communication between the mobile device  108  and vehicle  102 , the mobile device  108  transmits an access code or security code to the vehicle via electromagnetic signals  122  between electromagnetic transceiver  108   b  and electromagnetic transceiver  106 . In one embodiment, the security code is a code that is permanently stored at the mobile device  108 . In another embodiment, the security code is provided to the mobile device  108  on a temporary basis. For example, a temporary security code can be communicated to the mobile device  108  from a remote system  130 . Alternatively, the temporary security code can be communicated to the mobile device  108  before the mobile device  108  is dispatched from the remote system  130 . When the remote system  130  communicates the security code to the mobile device  108 , it also communicates the security code to the vehicle  102  so that the mobile device  108  can be verified at the vehicle  102 . The temporary security code can have a pre-set expiration time or can be cancelled wirelessly by an action taken at the remote system  130 . The vehicle  102  can initiate transfer of the security code to the mobile device  108  after receiving an access request from the mobile device  108 . The vehicle  102  can contact the remote system  130  in order for the remote system  130  to provide the security code to the mobile device  108  in response to the access request. The communication protocol between the mobile device  108  and vehicle  102  can provide a multi back-and-forth information exchange (e.g. more than two pass). 
     Referring to  FIG. 2 , with continuing reference to  FIG. 1 , a communication protocol  200  between mobile device  108  and vehicle  102  is illustrated. The mobile device  108  is shown on a left-hand side of  FIG. 2  and the vehicle  102  is shown on a right-hand side of  FIG. 2 . The mobile device  108  and vehicle  102  begin communication using an electromagnetic signal  122  to perform a handshake protocol (box  202 ). The mobile device  108  sends out the security code to electromagnetic transceiver  106  of vehicle  102 . The security code is sent from the electromagnetic transceiver  106  to the control unit  110  to thereby establish an ownership or other association between a person in possession of the mobile device  108  and the vehicle  102 . The control unit  110  determines whether the security code matches a code stored at the control unit  110 . When the security code matches the stored code, the control unit  110  activates (box  204 ) the transceivers  104   a ,  104   b ,  104   c  and  104   d  in order to commence communication with the mobile device  108  using acoustic signals. The control unit  110  may also send (box  202 ) an electromagnetic signal back to the mobile device  108  to tell the mobile device  108  to expect communications via acoustic signals in order that the mobile device  108  can activate (box  206 ) its acoustic transceiver  108   a.    
     Once transceivers  104   a ,  104   b ,  104   c  and  104   d  and acoustic transceiver  108   a  have been activated, the mobile device  108  and vehicle  102  send acoustic signals back and forth (boxes  208 ) in order to determine (box  210 ) a location of the mobile device  108  with respect to the vehicle  102 . 
     The location of the mobile device  108  can be determined by triangulation of the acoustic signals. In one embodiment, each transceiver  104   a ,  104   b ,  104   c ,  104   d  transmits an acoustic signal to the mobile device  108 . For each acoustic signal received at the mobile device  108 , the mobile device  108  transmits an acoustic signal in response. Each transceiver  104   a ,  104   b ,  104   c ,  104   d  determines a radial distance to the mobile device  108  (or range of the mobile device  108 ) from a time-of-flight between transmission and reception of acoustic signals. Calculating the crossing point of the circles associated with these radial distance measurements (i.e., triangulation) provides the location of the mobile device  108 . The transceivers  104   a ,  104   b ,  104   c ,  104   d  can transmit signals simultaneously or sequentially. Alternatively, the mobile device  108  can transmit an acoustic signal and the transceivers  104   a ,  104   b ,  104   c  and  104   d  can determine the location of the mobile device from the acoustic signal. In an embodiment, the transceivers  104   a ,  104   b ,  104   c  and  104   d  each measure an intensity of the received acoustic signal and the control unit  110  determines the location of the mobile device  108  from the difference in the intensities. Alternatively, the control unit  110  can determine location of the mobile device  108  by recoding times at which the acoustic signals are received at each of the transceivers  104   a ,  104   b ,  104   c  and  104   d . In another embodiment, the transceivers  104   a ,  104   b ,  104   c  and  104   d  transmit acoustic signals with audio codes and the mobile device  108  determines its location with respect to the vehicle  102 . The mobile device  108  can transmit its determined location to the vehicle  102 . In another embodiment, a combined version of ranging by time of flight measurements and power measurements can be used to calculate the location of the mobile device  108  relative to the vehicle  102 . In another embodiment, the mobile device  108  transmits a voice code or signal and the transceivers  104   a ,  104   b ,  104   c  and  104   d  calculate the time of arrival of this signal. The times, which are measured relative to the vehicle  102  as measured at a local clock system of the vehicle  102 , are differenced and the time difference of arrivals is used to calculate the location of the mobile device  108  relative to the vehicle  102 . 
     The control unit  110  can perform any number of operations based on the determined location of the mobile device  108 . For example, box  212  of  FIG. 2  indicates that a door, such as a driver-side front door, can be opened when the mobile device  108  is within a set distance of the vehicle  102 . The control unit  110  can track the movement of a person holding the mobile device  108  and determine that the person is approaching the vehicle  102  in order to enter the vehicle. Since the security code of the mobile device  108  has been confirmed, the control unit  110  can open the door for the person. 
     Additionally, the control unit  110  may start the vehicle  102  when the mobile device  108  is determined to be inside the vehicle  102 . More particularly, the control unit  110  can start the vehicle  102  when the mobile device  108  is determined to be inside the vehicle  102  and driver&#39;s side door is determined to be closed or a button is pushed or some other associated condition is met or action is performed. When the mobile device  108  is a mobile phone or is associated with a mobile phone, the control unit  110  may connect the mobile phone to the vehicle  102  so that phone calls are directed through the vehicle  102 . In another embodiment, the control unit  110  can prevent the vehicle  102  from being locked when the mobile device  108  is within a cabin of the vehicle  102 . Alternatively, the vehicle  102  can call a separate phone when a driver locks the vehicle  102  with the mobile device  108  inside the vehicle  102 . In another embodiment, when a person leaves the vehicle without the mobile device  108 , the control unit  110  prevents the vehicle  102  from being locked or sounds an alarm. The vehicle  102  can select to use the externally-mounted transceivers  104   a ,  104   b ,  104   c  and  104   d  when the mobile device  108  is external to the vehicle  102  and the internally-mounted transceivers  104   e ,  104   f ,  104   g  and  104   h  when the mobile device  108  is internal to the vehicle  102 . 
       FIG. 3  is a graph  300  illustrating range determination for a mobile device  108  placed at a selected location with respect to a transceiver using the acoustic signals discussed herein. Time is shown in seconds along the abscissa and range is shown in centimeters along the ordinate axis. Dots indicate locations determined for the mobile device  108  at various points in time. As an illustrative example, using acoustic signals having a frequency of f=30 kHz and a velocity of sound is about v=340 meters/second, the wavelength of such acoustic signals about 1.13 centimeters. Therefore, the control unit  110  can determine the location of the mobile device  108  to within about 1.13 centimeters. The control unit  110  can therefore determine the location of the mobile device  108  with a high degree of accuracy.  FIG. 3  shows that the range of the mobile device  108  is determined to within about 1 centimeter consistently over a time interval of about 2500 seconds (about 41 minutes), thereby demonstrating the viability of the invention. 
     The disclosure herein therefore provides a system and method for determining a location of a mobile device  108  with respect to a vehicle and enables the control unit  110  to perform an action that coincides with the actions or intentions of a driver or passenger of the vehicle  102 . 
     While the above disclosure has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from its scope. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but will include all embodiments falling within the scope of the application.