Patent Application
20140308971
One or more embodiments relate to a vehicle system and method for determining a location of a wireless device about a vehicle in three dimensions.
Many modern vehicles are equipped one or more transceivers for communicating with a key fob using radio signals for controlling vehicle functions, such as passive keyless entry and passive starting. With passive entry, a vehicle controller determines which door to unlock based on the location of the key fob with respect to the vehicle. Such passive keyless entry systems often include up to six low frequency (LF) antennas. Each LF antenna is mounted proximate to a vehicle door (e.g., within the handle) and communicates with the key fob to determine its location. With passive start, a vehicle controller determines whether the driver is inside the vehicle or outside the vehicle based on the fob location. Such passive start systems often include at least one antenna inside of the vehicle, and another antenna externally mounted to the vehicle, (e.g., on the roof). Thus a vehicle equipped with a passive entry/passive start (PEPS) system may have up to eight antennas.
In at least one embodiment, a vehicle system is provided with a portable device that is configured to provide a wireless signal. The vehicle system includes at least three base stations for being positioned about a vehicle within a first plane and a fourth base station for being positioned within the vehicle and vertically offset from the first plane to define a second plane with two of the at least three base stations. Each base station is configured to receive the wireless signal and to generate a message indicative of a time of flight of the wireless signal. The fourth base station is further configured to determine a three-dimensional location of the portable device based on the message generated by each base station.
The embodiments of the present disclosure are pointed out with particularity in the appended claims. However, other features of the various embodiments will become more apparent and will be best understood by referring to the following detailed description in conjunction with the accompanying drawings in which:
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components.
Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
The embodiments of the present disclosure generally provide for a plurality of circuits or other electrical devices. All references to the circuits and other electrical devices and the functionality provided by each, are not intended to be limited to encompassing only what is illustrated and described herein. While particular labels may be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the scope of operation for the circuits and the other electrical devices. Such circuits and other electrical devices may be combined with each other and/or separated in any manner based on the particular type of electrical implementation that is desired. It is recognized that any circuit or other electrical device disclosed herein may include any number of microprocessors, integrated circuits, memory devices (e.g., FLASH, RAM, ROM, EPROM, EEPROM, or other suitable variants thereof) and software which co-act with one another to perform any number of the operation(s) as disclosed herein.
Referring to
The main base station 14, the auxiliary base stations 16, and the fob 12 engage in a series of signal exchanges with one another and utilize a time of flight (TOF) implementation to determine a distance of the fob 12 from the vehicle 18. Thereafter, the nodes 14, 16 employ trilateration to locate the actual zone 20 that the fob 12 is positioned within. The use of trilateration enables the main base station 14 to locate where the fob 12 is positioned horizontally from the vehicle. The vertical offset between the fourth node 14 and the other nodes (16a, 16b, 16n) enables the vehicle system 10 to calculate a three-dimensional (3-D) location of the fob 12 relative to multiple planes, using trilateration. Such 3-D analysis provides for a more accurate location determination, than 2-D analysis relative to a single plane. This information (e.g., which zone 20 the fob 12 is positioned within) coupled with distance information as ascertained by utilizing TOF enables the main base station 14 to locate with increased levels of accuracy the location of the fob 12 in relation to the vehicle 18.
For example, the main base station 14 may determine that the fob 12 is positioned at a distance of three meters away from the vehicle 18 and that the fob 12 is positioned in the driver side zone 20a. While it is noted that the location of the fob 12 may be ascertained via the TOF and trilateration, it is recognized that the aspects noted herein with respect to locating the fob 12 may be applicable to other vehicle functions such as, but not limited to, tire pressure monitoring. While utilizing the TOF, it is recognized that the main base station 14 and the auxiliary base stations 16 may be positioned at predetermined locations in the vehicle 18 for transmitting and receiving signals to and from the fob 12. In one or more embodiments the nodes 14, 16 are located within a vehicle headliner (as shown in
The main base station 14 generally includes additional circuitry to lock and unlock the vehicle 18 in response to command signals as provided by the fob 12. The vehicle system 10 performs a passive entry passive start (PEPS) function in which the main base station 14 unlocks the vehicle 18 in response to determining that the fob 12 is positioned in a corresponding zone 20a-20n (“20”) about the vehicle. For example, the illustrated embodiment depicts a front driver side zone 20a, a vehicle front zone 20b, a front passenger side zone 20c, a rear passenger side zone 20d, a vehicle rear zone 20e, and a rear driver side zone 20f. The zones 20 generally correspond to predetermined authorized locations about the vehicle 18 (e.g., interior to and exterior to the vehicle 18) such that if the fob 12 is detected to be in one of such zones 20, then the main base station 14 may automatically unlock the vehicle (or door) proximate to the zone 20 in which the fob 12 is detected to be within and enable the user to start the vehicle.
The vehicle system 10 utilizes remote keyless operation in addition to the PEPS function, according to one or more embodiments. For example, the main base station 14 may perform a desired operation (e.g., lock, unlock, lift gate release, etc.) with the vehicle 18 in the event the fob 12 transmits a command indicative of the desired operation while within the authorized zone 20.
The fob 12 includes a rechargeable battery 36 that powers the microcontroller 30 and the transceiver 32 according to one or more embodiments. A battery charger circuit 40 receives power from a charger connector 42 that is operably coupled to an external power supply (not shown). The microcontroller 30 may control a first lighting indicator 44 and/or a vibrating motor 46 to provide feedback to the user that is indicative of the state of charge of the battery 36. The fob 12 may also include an accelerometer 47 and a gyroscope 48 for detecting the motion of the wireless device 12. The accelerometer 47 may provide data that is indicative of the acceleration of the fob 12 in three axis (Ax, Ay, and Az). The gyroscope 48 may provide orientation data that is indicative of a yaw rate (Ψ), a pitch rate (θ), and a roll rate (φ) of the fob 12. Further, a piezo-sounder 49 and a second lighting indicator may also be operably coupled to the microcontroller 30 for providing additional feedback. A plurality of switches 52 are positioned on the wireless device 12 for transmitting commands to the vehicle 18 for initiating a number of vehicle operations (e.g., door lock and unlock, lift gate release, remote start, etc.).
The transceiver 32 is generally configured to operate at a frequency of between 3 and 10 GHz and communicate within an ultra-wide band (UWB) bandwidth of at least 500 MHz. Such high frequency communication in the UWB bandwidth enables the vehicle system 10 to determine a distance of the fob 12 with respect to the vehicle within a high degree of accuracy. The transceiver 32 generally includes an oscillator 54 and a phase locked loop (PLL) 56 for enabling the transceiver 32 to operate at the frequency of between 3 and 10 GHz.
The microcontroller 30 is operably coupled to the transceiver 32 and the antenna 34 for transmitting a wireless signal 58 to the main base station 14 and each auxiliary base station 16. The wireless signal 58 includes data such as encryption data, the acceleration data (Ax, Ay, and Az), and the gyroscope data (Ψ, θ, and φ) according to one or more embodiments.
The main base station 14 generally includes a microcontroller 60, a transceiver 62, and at least one antenna 64. A power source 65 in the vehicle 18 powers the microcontroller 60 and the transceiver 62. An RF switch 66 is operably coupled to the microcontroller 60 and to the antenna 64. The RF switch 66 is operably coupled to the antennas 64 for coupling the same to the transceiver 62. A multiple antenna 64 implementation may provide for antenna diversity which may aid with respect to RF multi-paths. It is also contemplated that a single antenna 64 may be used for transmitting and receiving signal to and from the fob 12 without the need for the RF switch 66. The microcontroller 60 is operably coupled to the transceiver 62 and the antenna 64 for transmitting and receiving signals to/from the fob 12 (e.g., the wireless signal 58) and the auxiliary base station 16. The microcontroller 60 determines the position of the fob 12 based on these signals. The main base station 14 further includes circuitry (not shown) for performing locking/unlocking of vehicle doors and/or a liftgate/trunk and for performing remote start operation.
The transceiver 62 is also generally configured to operate at a frequency of between 3 and 10 GHz and communicate within an ultra-wide band (UWB) bandwidth of at least 500 MHz. Operating the transceiver 62 at an operating frequency of between 3 and 10 GHz and within the UWB bandwidth may enable the main base station 14 to determine the distance of the fob 12 with respect to the vehicle within a high degree of accuracy when it engages in communication with the fob 12. The transceiver 62 generally includes an oscillator 74 and a PLL 76 for enabling the transceiver 62 to operate at the frequency of between 3 and 10 GHz.
The auxiliary base station 16 generally includes a microcontroller 80, a transceiver 82, and at least one antenna 84. An RF switch 86 is operably coupled to the microcontroller 60 and to the antenna 64. The RF switch 86 and the multi-antenna 84 implementation are optional for the reasons noted above. The microcontroller 80 is operably coupled to the transceiver 82 and the antenna 84 for transmitting and receiving signals to/from the fob 12 (e.g. the wireless signal 58) and the main base station 14. The power source 65 in the vehicle 18 powers the microcontroller 80 and the transceiver 82.
The transceiver 82 is also generally configured to operate at a frequency of between 3 and 10 GHz and communicate within an ultra-wide band (UWB) bandwidth of at least 500 MHz. Operating the transceiver 82 at an operating frequency of between 3 and 10 GHz enables the vehicle system 10 to determine the distance of the fob 12 with respect to the vehicle within a high degree of accuracy when it engages in communication with the fob 12. The transceiver 82 generally includes an oscillator 94 and a PLL 96 for enabling the transceiver 62 to operate at the frequency of between 3 and 10 GHz. It is recognized that the second and third auxiliary base stations 16b, 16n (shown in
Each auxiliary base station 16 receives the wireless signal 58 from the fob 12, and transmits a message 98 to the main base station 14 that includes information that is indicative of the time of flight of the wireless signal. The message 98 may also include the acceleration data (Ax, Ay, and Az) and the gyroscope data (Ψ, θ, and φ). The main base station 14 also receives the wireless signal 58 and generates a message (not shown) that includes information that is indicative of the time of flight of the wireless signal 58 along with the acceleration and gyroscope data. The auxiliary base stations 16 may communicate wirelessly with the main base station 14, or through a wired connection. In one embodiment the auxiliary base stations 16 communicate with the main base station 14 using a local interconnect network (LIN).
The fob 12, the main base station 14, and the auxiliary base stations 16 are each arranged to transmit and receive data within the UWB bandwidth of at least 500 MHz, this aspect may place large current consumption requirements on such devices. For example, by operating in the UWB bandwidth range, such a condition yields a large frequency spectrum (e.g., both low frequencies as well as high frequencies) and a high time resolution which improves ranging accuracy. Power consumption may not be an issue for the main base station 14 and the auxiliary base station 16 since such devices are powered from the power source 65 in the vehicle. However, this may be an issue for the fob 12 since it is a portable device. Generally, portable devices are equipped with a standalone battery. In the event the standalone battery is implemented in connection with the fob 12 that transmits/receives data in the UWB bandwidth range, the battery may be depleted rather quickly. To account for this condition, the fob 12 includes the rechargeable battery 36 and the battery charger circuit 40, along with the charger connector 42 (or wireless implementation) such that the battery 36 can be recharged as needed to support the power demands used in connection with transmitting/receiving information in the UWB bandwidth range.
Existing PEPS systems (not shown) often include up to eight LF antennas that are located about the vehicle. The structure of the vehicle blocks the LF signals, therefore the antennas are mounted externally, or near windows to provide line of sight communication. Such systems often determine the location of the key fob based on a received signal strength (RSS) of a wireless signal.
The vehicle system 10 communicates at high frequency (e.g., 3-10 GHz) which allows for a reduced number of antennas as compared to existing systems. In general, the higher the operating frequency of the transceivers 32, 62, and 82; the larger the bandwidth that such transceivers 32, 62, and 82 can transmit and receive information. Such a large bandwidth (i.e., in the UWB bandwidth) may improve noise immunity and improve signal propagation. This may also improve the accuracy in determining the distance of the fob 12 since UWB bandwidth allows a more reliable signal transmission. As noted above, an operating frequency of 3-10 GHz enables the transceivers 32, 62, and 82 to transmit and receive data in the UWB range. The utilization of the UWB bandwidth for the fob 12, the main base station 14, and the auxiliary base stations 16 may provide for (i) the penetration of the transmitted signals to be received through obstacles (e.g., improved noise immunity), (ii) high ranging (or positioning) accuracy, (iii) high-speed data communications, and (iv) a low cost implementation. Due to the plurality of frequency components in the UWB spectrum, transmitted data may be received at the fob 12, the main base station 14, and the auxiliary base station 16 more reliably when compared to data that is transmitted in connection with a narrow band implementation (e.g., carrier frequency based transmission at 315 MHz, etc.). For example, UWB based signals may have both good reflection and transmission properties due to the plurality of frequency components associated therewith. Some of the frequency components may transmit through various objects while others may reflect well off of objects. These conditions may increase the reliability in the overall reception of data at the fob 12, the main base station 14, and the auxiliary base stations 16. Further, transmission in the UWB spectrum may provide for robust wireless performance against jamming. This may also provide for an anti-relay attack countermeasure and the proper resolution to measure within, for example, a few centimeters of resolution.
The implementation of UWB in the fob 12, the main base station 14, and the auxiliary base stations 16 is generally suitable for TOF applications. Although UWB based signals may have good reflection properties, the TOF calculations may become complicated if based on reflected signals. Therefore the base stations 14, 16 are mounted within the passenger compartment and near windows or the windshield (e.g., within the headliner or dashboard) to allow for generally line of sight communication with the fob 12.
The vehicle system 10 determines a distance between the fob 12 and each node (main base station 14 and auxiliary base stations 16) using TOF. The vehicle system 10 then determines a 3-D location of the fob 12, including which zone 20 (shown in
At operation 112, the vehicle system 10 determines a location of the fob 12 relative to Node Plane 1. This fob location may be referenced as “Location 1”.
If the fob 12 is presently located at the same vertical height as the first node plane, then the distances D2, D3, and D4 would correspond to the actual horizontal distance of the fob 12 from each node 16. However, the greater the vertical offset between the fob 12 and the nodes 16, the greater the horizontal difference between the calculated distance (e.g., D2) and the actual horizontal distance (e.g., D2X). For example, in one embodiment, the vertical displacement D2Z equals 24.00 inches, and D2X equals 49.49 inches. The vehicle system 10 calculates D2 to be 55.00 inches. The difference between D2 and D2X is 5.51 inches. This difference is referred to as a hypotenuse error. If the vehicle system 10 only relied on the 2-D determination of Location 1, then this hypotenuse error could prevent the vehicle system 10 from properly locating the wireless device 12 within the proper zone, or inside/outside of the vehicle. For example, if a user is sitting in the driver's seat and generally below a base station, then the vehicle system might “push” the location of the keyfob outside of the vehicle, and not allow the user to passively start the vehicle.
At operation 114, the vehicle system 10 determines a location of the fob 12 relative to Node Plane 2. This fob 12 location may be referenced as “Location 2”.
At operation 116, the vehicle system 10 determines a 3-D location of the fob 12 based on Location 1 and Location 2.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
