CONTROL DEVICE, SYSTEM AND CONTROL METHOD

Abstract

To estimate the positional relationship between devices that have transmitted and received signals with higher accuracy.SOLUTION: A control device includes a control unit that, based on signals transmitted and received between a communication device having at least three or more antennas and another communication device, performs control to estimate a positional relationship between the communication device and the other communication device. The control unit performs control to apply weighting parameters based on a reliability parameter, which is an index indicating a degree of whether each signal is suitable as a processing target to estimate the positional relationship between the communication device and the other communication device calculated based on the signals which the communication device received from the other communication device, to at least two or more provisional positional relationships between the communication device and the other communication device estimated based on the signals transmitted and received by the communication device and the other communication device, and estimate the positional relationship between the communication device and the other communication device.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a control device, a system, and a control method. [Background technology]

[0002] In recent years, a technique has been disclosed for estimating the positional relationship between devices based on the results of transmitting and receiving wireless signals between the devices. For example, Patent Document 1 discloses a technique in which an ultra-wide band (UWB) receiver estimates the incident angle of a signal from a UWB transmitter using an UWB signal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 176776 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the technology described in Patent Document 1 above had a problem in that it did not address the possibility that the accuracy of estimating the signal incidence angle may decrease in environments where an obstruction is present between the transmitter and receiver.

[0005] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a new and improved control device, system, and control method that are capable of estimating the positional relationship between devices that transmit and receive signals with greater accuracy. [Means for solving the problem]

[0006] In order to solve the above problem, according to one aspect of the present invention, a control device is provided that includes a control unit that performs control to estimate a positional relationship between a communication device having at least three or more antennas and another communication device based on signals transmitted and received between the communication device and the other communication device, and the control unit applies a weighting parameter based on a reliability parameter that is an index indicating the degree to which the communication device is suitable as a processing target for estimating the positional relationship between the communication device and the other communication device, calculated based on the signals received by the communication device from the other communication device, to tentative positional relationships between at least two or more of the communication devices and the other communication devices estimated based on the signals transmitted and received by the communication device and the other communication devices, and performs control to estimate the positional relationship between the communication device and the other communication devices.

[0007] In addition, in order to solve the above problem, according to another aspect of the present invention, a system is provided, comprising a communication device having at least three or more antennas, another communication device having at least one or more antennas, and a control device that performs control to estimate a positional relationship between the communication device and the other communication device based on signals transmitted and received between the communication device and the other communication device, wherein the control device applies a weighting parameter based on a reliability parameter that is an index indicating the degree to which the communication device is appropriate as a processing target for estimating the positional relationship between the communication device and the other communication device, calculated based on the signals received by the communication device from the other communication device, to tentative positional relationships between at least two or more of the communication devices and the other communication devices estimated based on the signals transmitted and received by the communication device and the other communication devices, and performs control to estimate the positional relationship between the communication device and the other communication devices.

[0008] In addition, in order to solve the above problem, according to another aspect of the present invention, there is provided a control method executed by a computer, comprising: transmitting and receiving signals between a communication device having at least three or more antennas and another communication device; and performing control to estimate a positional relationship between the communication device and the other communication device based on the transmitted and received signals, wherein the controlling to estimate the positional relationship between the communication device and the other communication device comprises applying a weight parameter based on a reliability parameter which is an index indicating the degree to which the communication device is appropriate as a processing target for estimating the positional relationship between the communication device and the other communication device, calculated based on the signal received by the communication device from the other communication device, to tentative positional relationships between at least two or more of the communication devices and the other communication devices estimated based on the signals transmitted and received by the communication device and the other communication device, and performing control to estimate the positional relationship between the communication device and the other communication device. Effect of the Invention

[0009] As described above, according to the present invention, it is possible to estimate the positional relationship between devices that transmit and receive signals with higher accuracy. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a system 1 according to an embodiment of the present invention. [Diagram 2] FIG. 1 is an explanatory diagram for explaining an example overview of a system 1 according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating an example of a communication processing block of a communication unit 220 according to the present embodiment. [Figure 4] 13 is a graph showing an example of the CIR output from an integrator 229 according to the present embodiment. [Diagram 5] FIG. 2 is a diagram illustrating an example of a communication processing block of a communication unit 220 according to the present embodiment. [Figure 6A] FIG. 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter according to a first specified value. [Figure 6B]FIG. 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a linear function as a prescribed function. [Figure 6C] 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a trigonometric function as a prescribed function; FIG. [Figure 6D] FIG. 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter using an exponential function as a prescribed function. [Figure 7A] FIG. 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter according to a first specified value. [Figure 7B] FIG. 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a linear function as a prescribed function. [Figure 7C] 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a trigonometric function as a prescribed function; FIG. [Figure 7D] FIG. 11 is an explanatory diagram for explaining an example of a method for calculating a weight parameter using an exponential function as a prescribed function. [Figure 8] FIG. 2 is an explanatory diagram for explaining an example of an operation process of the system 1 according to the first embodiment. [Figure 9] FIG. 2 is a block diagram showing an example of the configuration of a vehicle 20 according to a second embodiment and a third embodiment. [Figure 10] FIG. 11 is an explanatory diagram for explaining a control example of the system 1 according to the second embodiment. [Figure 11] FIG. 11 is an explanatory diagram for explaining an example of an operation process of the system 1 according to the second embodiment. [Figure 12] FIG. 11 is an explanatory diagram for explaining a control example of the system 1 according to the third embodiment. [Figure 13] FIG. 11 is an explanatory diagram for explaining another control example of the system 1 according to the third embodiment. [Figure 14] FIG. 11 is an explanatory diagram for explaining an example of an operation process of the system 1 according to the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and duplicated explanations will be omitted.

[0012] In addition, in this specification and drawings, elements having substantially the same functional configuration may be distinguished by adding different letters or numbers after the same reference numeral. For example, multiple elements having substantially the same functional configuration may be distinguished as in-vehicle devices 200-1 and 200-2 as necessary. However, when there is no need to particularly distinguish between multiple elements having substantially the same functional configuration, only the same reference numeral may be added. For example, when there is no need to particularly distinguish between in-vehicle devices 200-1 and 200-2, they are simply referred to as in-vehicle device 200.

[0013] <<1. Configuration example>> Fig. 1 is a block diagram showing an example of a configuration of a system 1 according to an embodiment of the present invention. As shown in Fig. 1, the system 1 according to the present embodiment includes a portable device 100, an in-vehicle device 200, a control device 300, and an operating device 400.

[0014] The vehicle-mounted device 200, the control device 300, and the operating device 400 according to this embodiment are mounted on a vehicle 20. The vehicle 20 is an example of a moving body, and is, for example, a vehicle in which a user is permitted to ride (for example, a vehicle owned by the user or a vehicle temporarily loaned to the user). Note that the moving body according to this embodiment includes not only the vehicle 20, but also an airplane, a ship, and the like.

[0015] (Portable device 100) The portable device 100 is an example of another communication device, and is a device configured by a user who uses the vehicle 20. The portable device 100 may be an electronic key, a smartphone, a tablet terminal, a wearable terminal, or the like. As shown in FIG. 1, the portable device 100 includes a control unit 110 and a communication unit 120.

[0016] The control unit 110 controls the overall operation of the portable device 100. For example, the control unit 110 causes the communication unit 120 to transmit a Polling signal (described later). The control unit 110 also causes the communication unit 120 to transmit a Final signal (described later). The control unit 110 is configured with electronic circuits such as a CPU (Central Processing Unit) and a microprocessor.

[0017] The communication unit 120 performs wireless communication with the communication unit 220 included in the vehicle-mounted device 200. For example, the communication unit 120 transmits a Poll signal under the control of the control unit 110. The communication unit 120 also receives a Resp (Response) signal transmitted from the communication unit 220 included in the vehicle-mounted device 200 as a response to the transmitted Poll signal. The communication unit 120 also transmits a Response signal under the control of the control unit 110 as a response to the received Resp signal.

[0018] Wireless communication between the communication unit 120 and the communication unit 220 included in the vehicle-mounted device 200 is realized, for example, by a signal conforming to ultra-wideband wireless communication (hereinafter referred to as UWB signal). In wireless communication by UWB signal, if an impulse method is used, the air propagation time of the radio wave can be measured with high accuracy by using radio waves with a very short pulse width of less than nanoseconds, and positioning and ranging based on the propagation time can be performed with high accuracy. The communication unit 120 is configured, for example, as a communication interface capable of communication by UWB signal.

[0019] The UWB signal can be transmitted and received as a ranging signal and a data signal. The ranging signal is a Poll signal, a Resp signal, and a Final signal transmitted and received in a ranging process described later. The ranging signal may be configured in a frame format that does not have a payload portion for storing data, or may be configured in a frame format that has a payload portion. On the other hand, it is preferable that the data signal is configured in a frame format that has a payload portion for storing data.

[0020] The communication unit 120 also has at least one antenna 111. The communication unit 120 transmits and receives wireless signals via at least one antenna 121.

[0021] (Onboard device 200) The vehicle-mounted device 200 is an example of a communication device, and is a device mounted on the vehicle 20. As shown in FIG.

[0022] The control unit 210 controls the overall operation of the vehicle-mounted device 200. For example, the control unit 210 causes the communication unit 220 to transmit a Resp signal, which will be described later. The control unit 210 is constituted by electronic circuits, such as a CPU and a microprocessor.

[0023] The communication unit 220 performs wireless communication with the communication unit 120 included in the portable device 100. The communication unit 220 receives a Poll signal transmitted from the communication unit 120 included in the portable device 100. Furthermore, the communication unit 220 transmits a Resp signal as a response to the received Poll signal under the control of the control unit 210. Furthermore, the communication unit 220 receives a Fianl signal transmitted from the communication unit 120 included in the portable device 100 as a response to the transmitted Resp signal.

[0024] Moreover, the communication unit 220 has at least three or more antennas 221. The communication unit 220 transmits and receives wireless signals via the three or more antennas 221. However, when the control device 30 according to the present invention is applied to a first embodiment described later, the communication unit 220 needs to have at least four or more antennas 221.

[0025] (Control device 300) The control device 300 performs control to calculate a positional relationship between the portable device 100 and the vehicle-mounted device 200. As shown in Fig. 1, the control device 300 includes a communication unit 310 and a control unit 320. Note that, in the description of this specification, an example in which the vehicle 20 according to the present embodiment is configured with the vehicle-mounted device 200 and the control device 300 separated from each other will be described, but the function of the control device 300 may be realized by the portable device 100 or the vehicle-mounted device 200.

[0026] The communication unit 310 performs various communications with the vehicle-mounted device 200 using an arbitrary communication method. For example, the communication unit 310 receives information on signals transmitted and received between the portable device 100 and the vehicle-mounted device 200 from the communication unit 220 included in the vehicle-mounted device 200. The arbitrary communication method may be wired communication or wireless communication. The communication unit 310 may also perform various communications with the communication unit 120 included in the portable device 100 using a wireless communication method.

[0027] The control unit 320 controls the overall operation of the control device 300. For example, the control unit 320 performs control to estimate a positional relationship between the portable device 100 and the vehicle-mounted device 200 based on a signal transmitted and received between the portable device 100 and the vehicle-mounted device 200. As shown in FIG. 1, the control unit 320 includes a parameter calculation unit 321 and a position estimation unit 325.

[0028] The control unit 320 is configured with electronic circuits such as a CPU and a microprocessor.

[0029] The parameter calculation unit 321 calculates a reliability parameter, which is an index indicating the degree to which a signal transmitted and received between the vehicle-mounted device 200 and the portable device 100 is appropriate as a processing target for estimating the positional relationship between the portable device 100 and the vehicle-mounted device 200, based on the signal. The reliability parameter will be described in detail later.

[0030] The position estimation unit 325 estimates the positional relationship between the portable device 100 and the vehicle-mounted device 200 based on a signal transmitted and received between the portable device 100 and the vehicle-mounted device 200. For example, the position estimation unit 325 calculates a distance measurement value between the portable device 100 and the vehicle-mounted device 200 based on a signal transmitted and received between the portable device 100 and the vehicle-mounted device 200. The position estimation unit 325 also estimates an arrival angle of a signal based on a signal received by the vehicle-mounted device 200 from the portable device 100. The position estimation unit 325 also calculates a two-dimensional position or a three-dimensional position of the portable device 100 based on the calculated distance measurement value and the arrival angle of the signal. Note that various processes related to the estimation of the positional relationship are executed using the reliability parameters calculated by the parameter calculation unit 321, and will be described in detail later.

[0031] (Operating device 400) The operating device 400 is a device that operates according to the control of the control device 300. The operating device 400 may be a door key of the vehicle 20, or may be an engine of the vehicle 20.

[0032] An example of the configuration of the system 1 according to this embodiment has been described above. Next, technical features of the system 1 according to this embodiment will be described with reference to FIGS.

[0033] <<2. Technical features>> <2.1. Multipath environment> In processing based on signals transmitted and received between the portable device 100 and the vehicle-mounted device 200, the accuracy of estimating the positional relationship may decrease depending on the radio wave propagation environment.

[0034] An example of such a situation is a case where an object such as a pillar is present in the communication path from the antenna 121 to the antenna 221. In this case, for example, the received power of the transmitted and received signal may decrease, and the estimation accuracy of the positional relationship may decrease accordingly.

[0035] Another example of such a situation is a situation where a multipath occurs. A multipath refers to a state where radio waves transmitted from a transmitter (e.g., communication unit 120) arrive at a receiver (e.g., communication unit 220) multiple times, and occurs when there are multiple radio wave paths between the transmitter and receiver. In a situation where a multipath occurs, radio waves that have passed through multiple different paths may interfere with each other, thereby reducing the accuracy of estimating the positional relationship.

[0036] Therefore, the positional relationship between the portable device 100 and the vehicle-mounted device 200 estimated by the position estimation unit 325 may include an estimation error caused by a multipath environment. Here, the control device 300 according to the present embodiment estimates the positional relationship between the portable device 100 and the vehicle-mounted device 200 using a reliability parameter that is an index indicating the degree to which the vehicle-mounted device 200 is suitable as a processing target for estimating the positional relationship between the portable device 100 and the vehicle-mounted device 200, calculated based on a signal received from the portable device 100. This can reduce the influence of the estimation error of the positional relationship caused by the above-mentioned multipath environment.

[0037] Hereinafter, an outline example of the system 1 according to this embodiment will be described with reference to FIG.

[0038] FIG. 2 is an explanatory diagram for explaining an outline example of the system 1 according to the present embodiment. As shown in FIG. 2, the communication unit 120 included in the portable device 100 has an antenna 121. Also, the communication unit 220 included in the vehicle-mounted device 200 has, for example, an antenna 221A, an antenna 221B, an antenna 221C, and an antenna 221D as a four-element array antenna. However, the number of antennas included in the communication unit 120 included in the portable device 100 and the communication unit 220 included in the vehicle-mounted device 200 is not limited to the example. For example, the number of antennas included in the communication unit 120 may be multiple, and the number of antennas 221 included in the communication unit 220 may be five or more. Also, in the case of applying the control device 300 according to the present invention in the second or third embodiment described later, the number of antennas 221 included in the communication unit 220 may be three.

[0039] Furthermore, the scale ratio of the communication unit 220 and the multiple antennas 221 that the communication unit 220 has is not limited to the scale ratio shown in the figure. For example, the antennas 221A, 221B, 221C, and 221D may be arranged at intervals of about 1 / 2 wavelength. The arrangement shape of the four antennas may be a square, a parallelogram, a trapezoid, a rectangle, or any other shape. However, it is preferable that the multiple antennas 221 are arranged on a plane, not on the same straight line.

[0040] 2, the antenna 121 of the portable device 100 is disposed at the upper left end of the portable device 100, but the position of the antenna 121 of the portable device 100 is not limited to this example. For example, the antenna 121 may be disposed at any position of the portable device 100.

[0041] As shown in FIG. 2, for example, the antenna 121 may transmit and receive a signal S to and from at least one of a plurality of antennas 221 included in the communication unit 220.

[0042] Then, the communication unit 310 included in the control device 300 receives information related to the signal S transmitted and received between the portable device 100 and the vehicle-mounted device 200 from either the communication unit 120 or the communication unit 220. Next, the parameter calculation unit 321 may calculate a reliability parameter based on the transmitted and received signal S. Furthermore, the position estimation unit 325 may estimate a positional relationship between the portable device 100 and the vehicle-mounted device 200 based on the transmitted and received signal S.

[0043] <2.2. CIR calculation process> The communication unit 120 included in the portable device 100 and the communication unit 220 included in the vehicle-mounted device 200 according to this embodiment can calculate a channel impulse response (CIR) that indicates the characteristics of a wireless communication path between the communication unit 120 and the communication unit 220 .

[0044] The CIR in this specification is calculated by one of the communication units 120 and 220 (hereinafter also referred to as the transmitting side) transmitting a radio signal including a pulse, and the other (hereinafter also referred to as the receiving side) receiving the radio signal. More specifically, the CIR in this specification is a correlation calculation result obtained by calculating the correlation between the radio signal transmitted by the transmitting side (hereinafter also referred to as the transmitted signal) and the radio signal received by the receiving side (hereinafter also referred to as the received signal) for each delay time, which is the elapsed time from the transmission of the transmitted signal.

[0045] The receiving side calculates the CIR by taking a sliding correlation between the transmission signal and the reception signal. More specifically, the receiving side calculates a value obtained by taking a correlation between the reception signal and the transmission signal delayed by a certain delay time as a characteristic at the delay time (hereinafter also referred to as a CIR value). Then, the receiving side calculates the CIR by calculating the CIR value for each delay time. That is, the CIR is a time series transition of the CIR value. Here, the CIR value is a complex number having an I component and a Q component. The sum of squares of the I component and the Q component of the CIR value may be referred to as the power value of the CIR. In addition, in a ranging technique using UWB, the CIR value is also referred to as a delay profile. In addition, in a ranging technique using UWB, the sum of squares of the I component and the Q component of the CIR value is also referred to as a power delay profile.

[0046] Hereinafter, the CIR calculation process in the case where the transmitting side is the portable device 100 and the receiving side is the vehicle-mounted device 200 will be described in detail with reference to FIGS.

[0047] 3 is a diagram showing an example of a communication processing block of the communication unit 220 according to the present embodiment. As shown in FIG. 3, the communication unit 220 includes an oscillator 222, a multiplier 223, a 90-degree phase shifter 224, a multiplier 225, an LPF (Low Pass Filter) 226, an LPF 227, a correlator 228, and an accumulator 229.

[0048] The oscillator 222 generates a signal having the same frequency as the frequency of the carrier wave that carries the transmission signal, and outputs the generated signal to the multiplier 223 and the 90-degree phase shifter 224 .

[0049] Multiplier 223 multiplies the signal received by antenna 221 by the signal output from oscillator 222, and outputs the multiplication result to LPF 226. LPF 226 outputs, of the input signals, signals having a frequency equal to or lower than the frequency of the carrier wave carrying the transmission signal, to correlator 228. The signal input to correlator 228 is the I component (i.e., the real part) of the components corresponding to the envelope of the received signal.

[0050] The 90-degree phase shifter 224 delays the phase of the input signal by 90 degrees and outputs the delayed signal to the multiplier 225. The multiplier 225 multiplies the signal received by the antenna 221 by the signal output from the 90-degree phase shifter 224, and outputs the multiplication result to the LPF 227. The LPF 227 outputs, of the input signals, signals having a frequency equal to or lower than the frequency of the carrier wave carrying the transmission signal to the correlator 228. The signal input to the correlator 228 is the Q component (i.e., the imaginary part) of the components corresponding to the envelope of the received signal.

[0051] The correlator 228 calculates the CIR by taking a sliding correlation between the received signal consisting of the I component and the Q component output from the LPF 226 and the LPF 227 and the reference signal. Note that the reference signal here is the same signal as the transmitted signal before being multiplied by the carrier wave.

[0052] The accumulator 229 accumulates the CIR output from the correlator 228 and outputs the accumulated result.

[0053] The communication unit 220 performs the above processing on each of the signals received by the multiple antennas 221.

[0054] FIG. 4 is a graph showing an example of the CIR according to this embodiment output from the integrator 229. The horizontal axis of the graph is the delay time, and the vertical axis is the delay profile. In the CIR, a piece of information that constitutes information that changes along a time series, such as the CIR value at a certain delay time, is also called a sampling point. In the CIR, typically, a set of sampling points between zero crossing points corresponds to one pulse. A zero crossing point is a sampling point where the value becomes zero. However, this is not the case in a noisy environment. For example, a set of sampling points between the intersection points of a reference level other than zero and the transition of the CIR value may be considered to correspond to one pulse. The CIR shown in FIG. 4 includes a set of sampling points 21 corresponding to a certain pulse and a set of sampling points 22 corresponding to another pulse.

[0055] Set 21 corresponds to, for example, fast-path pulses. Fast-path refers to the shortest path between transmitter and receiver, which refers to the straight-line distance between transmitter and receiver in an unobstructed environment. Fast-path pulses are pulses that have reached the receiver via a fast-path. Set 22 corresponds to, for example, pulses that have reached the receiver via a path other than the fast-path.

[0056] The pulse detected as the fast path pulse is also referred to as the first arriving wave. The first arriving wave can be either a direct wave, a delayed wave, or a composite wave. A direct wave is a signal that passes through the shortest path between the transmitter and the receiver and is received directly (i.e., without being reflected, etc.) by the receiver. In other words, a direct wave is a fast path pulse. A delayed wave is a signal that passes through a path that is not the shortest between the transmitter and the receiver, that is, is indirectly received by the receiver after being reflected, etc. A delayed wave is received by the receiver with a delay relative to the direct wave. A composite wave is a signal that is received by the receiver in a state in which multiple signals that have passed through multiple different paths are combined. In the following description, the first arriving wave may be simply referred to as a signal.

[0057] Next, an example of a flow of processing related to estimation of the positional relationship between the portable device 100 and the vehicle-mounted device 200 according to the present embodiment will be described.

[0058] <2.3. Estimation of positional relationship> (1) Distance Estimation The position estimation 325 performs a distance measurement process. The distance measurement process is a process for estimating the distance between the portable device 100 and the vehicle-mounted device 200. The distance measurement process includes transmitting and receiving a distance measurement signal, and estimating the distance between the portable device 100 and the vehicle-mounted device 200, i.e., a distance measurement value, based on the time required for transmitting and receiving the distance measurement signal.

[0059] In the distance measurement process, a plurality of distance measurement signals may be transmitted and received between the portable device 100 and the vehicle-mounted device 200. Of the plurality of distance measurement signals, a distance measurement signal transmitted from one device to another device is referred to as a Poll signal. A distance measurement signal transmitted in response to the Poll signal from a device that has received the Poll signal to a device that has transmitted the Poll signal is referred to as a Resp signal. A distance measurement signal transmitted in response to the Resp signal from a device that has received the Resp signal to a device that has transmitted the Resp signal is referred to as a Final signal. The portable device 100 and the vehicle-mounted device 200 can transmit and receive any distance measurement signals, but this specification describes an example in which the portable device 100 transmits a Poll signal.

[0060] (2) Arrival angle estimation The position estimation unit 325 estimates the angle of arrival of a signal transmitted and received between devices. In this specification, the Final signal included in the ranging signal will be described as a signal for estimating the angle of arrival.

[0061] Hereinafter, an example of processing relating to distance estimation and arrival angle estimation will be described with reference to FIG.

[0062] FIG. 5 is a sequence diagram for explaining an example of processing relating to estimation of a positional relationship between devices executed in the system 1 according to this embodiment.

[0063] First, the antenna 121 of the portable device 100 transmits a Poll signal to the antenna 221A of the vehicle-mounted device 200 (S101).

[0064] Next, the antenna 221A of the vehicle-mounted device 200 transmits a Resp signal to the antenna 121 of the portable device 100 in response to the Poll signal (S103).

[0065] Then, the antenna 121 of the portable device 100 transmits a Final signal to the antennas 221A, 221B, 221C, and 221D of the vehicle-mounted device 200 in response to the Resp signal (S105).

[0066] Here, the time length from when the portable device 100 transmits the Poll signal to when it receives the Resp signal is defined as time length T1, the time length from when it receives the Resp signal to when it transmits the Final signal is defined as time length T2, the time length from when the vehicle-mounted device 200 receives the Poll signal to when it transmits the Resp signal is defined as time length T3, and the time length from when it transmits the Resp signal to when it receives the Final signal is defined as time length T4.

[0067] The distance between the portable device 100 and the vehicle-mounted device 200 may be calculated using each of the time lengths described above. For example, the vehicle-mounted device 200 may receive a signal including information on the time length T1 and the time length T2 from the portable device 100. Then, the control device 300 may receive a signal including information on the time length T1, the time length T2, the time length T3, and the time length T4 from the vehicle-mounted device 200. Then, the position estimation unit 325 calculates the propagation time τ of the signal using the time length T1, the time length T2, the time length T3, and the time length T4. More specifically, the position estimation unit 325 may calculate the propagation time τ of the signal using the following Equation 1. τ=(T1×T4−T2×T3) / (T1+T2+T3+T4) (Formula 1)

[0068] Then, the position estimation unit 325 may estimate the distance between the portable device 100 and the vehicle-mounted device 200 by multiplying the calculated signal propagation time τ by a known signal speed.

[0069] An example has been described in which the position estimation unit 325 estimates the distance between the portable device 100 and the vehicle-mounted device 200 based on signals transmitted and received between the antenna 121 of the portable device 100 and the antenna 221A of the vehicle-mounted device 200, but the vehicle-mounted device 200 may transmit and receive signals using an antenna other than the antenna 221A, or may transmit and receive signals using multiple antennas 221.

[0070] Furthermore, the method of calculation of the signal propagation time τ is not limited to that of Equation 1. For example, the signal propagation time can also be calculated by subtracting the time length T3 from the time length T1 and dividing the result by 2.

[0071] Next, the arrival angle of the signal may be calculated from the phase difference between the Final signals received by adjacent antennas among the multiple antennas 221 of the vehicle-mounted device 200. For example, the phase of the Final signal received by the antenna 221A may be calculated as phase P A The phase of the Final signal received by the antenna 221B is P B The phase of the Final signal received by the antenna 221C is P C The phase of the Final signal received by the antenna 221D is P D Let us assume that.

[0072] For example, a coordinate system is defined in which the line connecting antenna 221A and antenna 221B is the X-axis, the line connecting antenna 221A and antenna 221C that is orthogonal to the X-axis is the Y-axis, and the vertical direction of antenna 221A is the Z-axis.

[0073] In this coordinate system, the phase difference between adjacent antennas in the X-axis direction is Pd AB , Pd CD , and the phase difference Pd between adjacent antennas in the Y-axis direction AC , Pd BD are expressed using the following Equation 2, respectively. Pd AB =(P B -P A ) Pd CD =(P D -P C) Pd AC =(P C -P A ) Pd BD =(P D -P B ) (Formula 2)

[0074] Here, the angle formed by the line connecting antenna 221A and antenna 221B (or antenna 221C and antenna 221D) and the first arriving wave is referred to as angle θ. Also, the angle formed by the line connecting antenna 221A and antenna 221C (or antenna 221B and antenna 221D) and the first arriving wave is referred to as angle Φ. Here, angles θ and Φ are the arrival angles of signals, and are each expressed by mathematical formula 3. Here, λ is the wavelength of the radio wave, and d is the distance between the antennas. θorΦ=arccos(λ×Pd / (2πd)) (Formula 3)

[0075] Therefore, the position estimation unit 325 calculates the arrival angle of the signal based on Equation 2 and Equation 3 using Equation 4. θ AB =arccos(λ×(P B -P A ) / (2πd)) θ CD =arccos(λ×(P D -P C ) / (2πd)) Φ AC =arccos(λ×(P C -P A ) / (2πd)) Φ BD =arccos(λ×(P D -P B ) / (2πd)) (Formula 4)

[0076] The position estimation unit 325 uses θ AB and θ CD Alternatively, the angle θ may be calculated as the average value of AB or θ CDSimilarly, the position estimation unit 325 may estimate the angle θ as an angle between either one of the angles Φ AC and Φ BD Alternatively, the angle Φ may be calculated as the average value of AC or Φ BD Alternatively, the angle Φ may be estimated as the angle Φ that forms one of the angles Φ.

[0077] Furthermore, the position estimation unit 325 may estimate the two-dimensional or three-dimensional position of the portable device 100 using the estimated distance measurement value and the angle θ or the angle Φ.

[0078] For example, in the above-mentioned coordinate system, the position estimation unit 325 may estimate the three-dimensional position of the portable device 100 using Equation 5. x=R×cosθ y=R×cosΦ z=√(R2-x2-y2) (Formula 5)

[0079] As described above, the position estimation unit 325 can estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 based on signals transmitted and received between the multiple antennas 221 of the vehicle-mounted device 200 and the antenna 121 of the portable device 100. On the other hand, as described above, the estimation accuracy of the positional relationship may be reduced depending on the multipath environment generated between the multiple antennas 221 of the vehicle-mounted device 200 and the antenna 121 of the portable device 100.

[0080] Therefore, based on a signal received by any of the antennas of the in-vehicle device 200 or the antenna 121 of the portable device 100, the position estimation unit 325 calculates a reliability parameter indicating the degree to which the signal transmitted and received between the multiple antennas 221 of the in-vehicle device 200 and the antenna 121 of the portable device 100 is appropriate as a processing target for estimating the positional relationship. By using a signal whose reliability parameter satisfies a predetermined criterion for estimating the positional relationship, the position estimation unit 325 can estimate the positional relationship between the portable device 100 and the in-vehicle device 200 with higher accuracy.

[0081] Hereinafter, a specific example of the reliability parameter calculated by the parameter calculation unit 321 will be described.

[0082] <2.4. Reliability parameters> The parameter calculation unit 321 according to this embodiment calculates a reliability parameter based on a signal received by the communication unit 220. Here, the received signal may be the above-mentioned Poll signal, Resp signal, or Final signal, or may be a signal transmitted from the portable device 100 separately from the ranging signal.

[0083] The reliability parameter is an index indicating the degree to which a signal received by the antenna 121 of the communication unit 120 or any one of the antennas 221 of the communication unit 220 is suitable as a processing target for estimating the positional relationship between the portable device 100 and the vehicle-mounted device 200. For example, the reliability parameter is a continuous value or a discrete value, and the larger the value, the more suitable the signal transmitted and received by the antenna is as a processing target for estimating the positional relationship, and the smaller the value, the less suitable the signal is as a processing target for estimating the positional relationship. In addition, the larger the reliability parameter value, the less suitable the signal transmitted and received by the antenna is as a processing target for estimating the positional relationship, and the smaller the value, the more suitable the signal is as a processing target for estimating the positional relationship. Below, a concrete example of the reliability parameter based on the signal received by the communication unit 220 will be described.

[0084] (An index showing the magnitude of noise) The reliability parameter may be, for example, an index indicating the magnitude of noise. More specifically, the parameter calculation unit 321 may calculate the reliability parameter based on at least one of the power value and SNR (signal noise ratio) of the signal received by the communication unit 220. When the power value or SNR is large, the influence of noise is small, and therefore a first reliability parameter indicating that the first arriving wave is appropriate as a target to be detected is calculated. On the other hand, when the power value or SNR is small, the influence of noise is large, and therefore a reliability parameter indicating that the first arriving wave is inappropriate as a target to be detected may be calculated.

[0085] (Indicator showing the validity that the first arriving wave is a direct wave) The reliability parameter is an index showing the validity that the first arriving wave is a direct wave. The higher the validity that the first arriving wave is a direct wave, the higher the reliability. The lower the validity that the first arriving wave is a direct wave, the lower the reliability.

[0086] For example, the reliability parameter may be calculated based on the consistency between signals at each of the multiple antennas 221 of the communication unit 220. More specifically, the parameter calculation unit 321 may calculate the reliability parameter based on at least one of the reception time and power value of the signal at each of the multiple antennas 221 of the communication unit 220. Due to the influence of multipath, multiple signals arriving via different paths may be combined and received by the antenna in a state in which they are amplified or offset with each other. If the amplification and offset of the signal differs in each of the multiple antennas, the reception time and power value of the signal may differ between the multiple antennas. Considering that the distance between the antennas is short, about 1 / 2 the wavelength of the arrival angle estimation signal, a large difference in the reception time and power value of the signal between the antennas 221A, 221B, 221C, and 221D means that it is less appropriate that the signal is due to a direct wave.

[0087] Therefore, a reliability parameter is calculated which indicates that the greater the difference in the reception time of the first arriving wave (i.e., the delay time of a specific element) between the multiple antennas 221, the lower the validity that the first arriving wave is due to a direct wave. On the other hand, a reliability parameter is calculated which indicates that the smaller the difference in the reception time of the first arriving wave between the multiple antennas 221, the higher the validity that the first arriving wave is due to a direct wave. Also, a reliability parameter is calculated which indicates that the greater the difference in the power of the first arriving wave between the multiple antennas 221, the lower the validity that the first arriving wave is due to a direct wave. On the other hand, a reliability parameter is calculated which indicates that the smaller the difference in the power of the first arriving wave between the multiple antennas 221, the higher the validity that the first arriving wave is due to a direct wave.

[0088] The reliability parameter may be calculated based on the consistency between position parameters indicating the position of the portable device 100, which are estimated based on the first incoming wave received by each of a plurality of antenna pairs formed by two different antennas (for example, antenna 221A and antenna 221B) among the plurality of antennas 221. The position parameters here are the distance measurement value, the angles θ and Φ, and the coordinates (x, y, z). When the first incoming wave is due to a direct wave, even if the combination of the antenna pairs of the communication unit 220 used to calculate the angles θ and Φ and the coordinates (x, y, z) is different, the results of the angles θ and Φ and the coordinates (x, y, z) are the same or approximately the same. However, when the first incoming wave is not due to a direct wave, the results of the angles θ and Φ and the coordinates (x, y, z) between the antenna pairs of the different communication units 220 may differ.

[0089] Therefore, a reliability parameter is calculated that indicates that the smaller the difference between the calculation results of the position parameters between different combinations of antenna pairs, the higher the validity that the first arriving wave is a direct wave. For example, Φ AC and Φ BD The smaller the error between and θ AB and θ CDA reliability parameter is calculated which indicates that the smaller the error between Φ and Φ, the higher the validity that the first arriving wave is due to a direct wave. On the other hand, a reliability parameter is calculated which indicates that the larger the difference between the calculation results of the position parameters between different combinations of antenna pairs, the lower the validity that the first arriving wave is due to a direct wave. For example, in the case of Φ AC and Φ BD The larger the error between and θ AB and θ CD A reliability parameter is calculated that indicates that the greater the error between the first arriving wave and the direct wave, the lower the likelihood that the first arriving wave is a direct wave. However, the reliability parameter calculated using the difference between the formed angles θ and Φ and the coordinates (x, y, z) is a reliability parameter for the entire antenna, and is therefore not applied in the first embodiment described later.

[0090] (Indicator showing the validity that the first arriving wave is not a composite wave) The reliability parameter may be an index indicating the validity that the first arriving wave is not due to a composite wave. The higher the validity that the first arriving wave is not due to a composite wave, the higher the reliability, and the lower the validity that the first arriving wave is not due to a composite wave, the lower the reliability. Specifically, the reliability parameter may be calculated based on at least one of the width of the first arriving wave in the time direction and the state of the phase of the first arriving wave.

[0091] (Indicator of the validity of the situation in which a radio signal is received) The reliability parameter may be an index indicating the validity of the situation in which the wireless signal is received, where the more valid the situation in which the wireless signal is received, the higher the reliability, and the less valid the situation in which the wireless signal is received, the lower the reliability.

[0092] For example, the reliability parameter may be calculated based on the variance of the first arriving waves. In this case, the reliability parameter may be calculated based on statistics indicating the variance of the first arriving waves, such as the variance of the power values ​​of the first arriving waves, and the variance and variation of the estimated position parameters (distance, angles θ and Φ, and coordinates (x, y, z)).

[0093] (The difference between the delay time of the first element and the delay time of the second element) The reliability parameter may be a difference between the delay time of a first element whose CIR value reaches a peak first after a specific element in the CIR, and the delay time of a second element whose CIR value reaches a peak second after the specific element. As shown in FIG. 4, the CIR waveform of the first arriving wave has one peak. On the other hand, when a composite wave is detected as the first arriving wave, the CIR waveform of the first arriving wave may have multiple peaks. Whether the CIR waveform of the first arriving wave has one peak or multiple peaks can be determined by the difference between the delay time of the first element and the delay time of the second element.

[0094] When the composite wave is detected as the first arriving wave, the estimation accuracy of the location parameters is lower than when the direct wave is detected as the first arriving wave. Therefore, the greater the difference between the delay time of the first element and the delay time of the second element, the higher the reliability.

[0095] (CIR waveform correlation) The reliability parameter may be derived based on the correlation of the CIR waveforms in a certain antenna pair among the multiple antennas 221 of the communication unit 220. When the direct wave and the delayed wave are received in a combined state in the multiple antennas 221 of the communication unit 220, the phase relationship between the direct wave and the delayed wave may differ between the antennas even if the distance between the antennas is short. As a result, the CIR waveforms in each antenna may be different. In other words, the difference in the CIR waveforms in a certain antenna pair means that the combined wave is received in at least one of the antennas in the antenna pair. When the combined wave is detected as the first arriving wave, i.e., when a specific element corresponding to the direct wave is not detected, the estimation accuracy of the location parameter decreases.

[0096] For example, the reliability parameter may be a correlation coefficient between a CIR obtained based on a signal received from one of the multiple antennas 221 included in the communication unit 220 and a CIR obtained based on a signal received from another antenna. In this case, the reliability parameter is determined to be lower the smaller the correlation coefficient, and higher the reliability. The correlation coefficient includes, for example, Pearson's correlation coefficient.

[0097] (supplement) Below, supplementary explanations will be given regarding specific examples of reliability parameters, which will be described subsequently.

[0098] First, each of the multiple sampling points included in the CIR is also referred to as an element below. That is, the CIR includes the CIR value for each delay time as an element. The shape of the CIR, more specifically, the shape of the time series change of the CIR value, is also referred to as the CIR waveform.

[0099] Among the multiple elements included in the CIR, a specific element is also referred to as a specific element below. The specific element is an element corresponding to the first arriving wave. The specific element is detected according to the predetermined detection criteria described above for the first arriving wave. As an example, the specific element is an element among the multiple elements included in the CIR, the amplitude or power as a CIR value of which exceeds a predetermined threshold first. Hereinafter, such a predetermined threshold is also referred to as a fast-path threshold.

[0100] The time corresponding to the delay time of the specific element is used as the reception time of the first arriving wave for ranging, and the phase of the specific element is used as the phase of the first arriving wave for estimating the arrival angle of the signal.

[0101] The multiple antennas 221 included in the communication unit 220 may include a mixture of communication units 220 in a Line of Sight (LOS) state and communication units 220 in a Non-Line of Sight (NLOS) state.

[0102] The LOS state means that there is line of sight between the antenna 221 of the vehicle-mounted device 200 and the antenna 121 of the portable device 100. In the LOS state, the received power of the direct wave is the largest, so that the receiving side is likely to succeed in detecting the direct wave as the first arriving wave.

[0103] The NLOS state means that there is no line of sight between the antenna 221 of the vehicle-mounted device 200 and the antenna 121 of the portable device 100. In the NLOS state, the received power of the direct wave may be smaller than the other waves, and the receiving side may fail to detect the direct wave as the first arriving wave.

[0104] When the communication unit 220 is in the NLOS state, the received power of the direct wave among the signals arriving from the portable device 100 is smaller than the noise. Therefore, even if the direct wave is successfully detected as the first arriving wave, the phase and the reception time of the first arriving wave may vary due to the influence of the noise. In that case, the accuracy of the distance measurement and the accuracy of the estimation of the arrival angle may decrease.

[0105] Furthermore, when the communication unit 220 is in the NLOS state, the received power of the direct wave is smaller than when the communication unit 220 is in the LOS state, and the direct wave may fail to be detected as the first arriving wave. In that case, the ranging accuracy and the arrival angle estimation accuracy may decrease.

[0106] (The difference between the delay time of a specific element and the delay time of the element with the maximum CIR value) Therefore, the reliability parameter may be the difference between the delay time of a specific element and the delay time of an element that has the maximum CIR value in the CIR.

[0107] If communication unit 220 is in an LOS state, the CIR value of the direct wave will be the largest, and therefore the element with the largest CIR value in the CIR will be included in the set corresponding to the direct wave.

[0108] On the other hand, in the NLOS state, the CIR value of the delayed wave may be larger than the CIR value of the direct wave. This is because an obstruction exists in the fast path in the NLOS state. In particular, if there is a human body in the fast path, the direct wave is significantly attenuated as it passes through the human body. In this case, the element with the maximum CIR value in the CIR is not included in the set corresponding to the direct wave.

[0109] Whether communication unit 220 is in the LOS state or the NLOS state can be determined based on the difference between the delay time of a specific element and the delay time of the element in the CIR that has the maximum CIR value.

[0110] This is because the difference may be small when communication unit 220 is in an LOS state, and the difference may be large when communication unit 220 is in an NLOS state.

[0111] The specific example of the reliability parameter according to the present embodiment has been described above. The position estimation unit 325 can improve the estimation accuracy of the positional relationship between the portable device 100 and the vehicle-mounted device 200 by using the reliability parameter calculated by the parameter calculation unit 321.

[0112] In addition to the reliability parameters described above, the position estimation unit 325 may use a distance measurement value as a reliability parameter, or may use a combination of a plurality of reliability parameters. Specific examples of using the reliability parameters will be described below.

[0113] <<3. Example>> <3.1. First Example> The control unit 320 of the first embodiment may apply a weighting parameter based on a reliability parameter calculated based on a signal received by the vehicle-mounted device 200 from the portable device 100 to the phase difference between adjacent antennas among the multiple antennas 221 possessed by the vehicle-mounted device 200, and perform control to estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200.

[0114] Here, the adjacent antennas refer to antennas 221A and 221B, antennas 221C and 221D, antennas 221A and 221C, and antennas 221B and 221D, which are shown in FIG.

[0115] The control unit 320 may, for example, perform a weighted average based on a weighting parameter on the phase difference between antennas in a parallel direction among the multiple antennas 221, and perform control to estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200. The antennas in the parallel direction are the antenna pair of antennas 221A and 221B parallel to the above-mentioned X-axis, and the antenna pair of antennas 221C and 221D. The antennas in the parallel direction are the antenna pair of antennas 221A and 221C parallel to the above-mentioned Y-axis, and the antenna pair of antennas 221B and 221D.

[0116] For example, the phase difference between antennas after weighting the average of each antenna pair parallel to the X-axis is called the phase difference between antennas Pd X The phase difference between antennas after weighting the average of each antenna pair parallel to the Y axis is Pd Y In addition, the phase difference between the antennas 221A and 221B is PdAB The weight parameter for AB and the phase difference between the antennas 221C and 221D is Pd CD The weight parameter for CD and the phase difference between the antennas 221A and 221C is Pd AC The weight parameter for AC and the phase difference between the antennas 221B and 221D is Pd BD The weight parameter for BD Let us assume that.

[0117] Here, the parameter calculation unit 321 calculates, for example, the value indicated by the reliability parameter as a weighting parameter W AB , W CD , W AC and W BD For example, when the reliability parameter is the above-mentioned reception power, when the reception power of the signal received by the antenna 221A is "-90 dBm" and the reception power of the signal received by the antenna 221B is "-100 dBm", the weight parameter W AB Alternatively, the weight parameter W may be set to "-95 dBm", which is the average value of "-90 dBm" and "-100 dBm". AB may be set to "-90 dBm", which is the maximum value of "-90 dBm" and "-100 dBm", or may be set to "-100 dBm", which is the minimum value. Alternatively, the weight parameter W AB may be the median value of the received power of multiple antennas 221.

[0118] Then, the position estimation unit 325 calculates the phase difference between the antennas in the X-axis direction Pd X and the phase difference between antennas in the Y-axis direction Pd Y may be estimated using Equation 6, respectively. Pd X =(W AB ×Pd AB +W CD ×Pd CD ) / (W AB +W CD) Pd Y =(W AC ×Pd AC +W BD ×Pd BD ) / (W AC +W BD ) (Formula 6)

[0119] Then, the position estimation unit 325 calculates the position Pd X Based on Equation 3, the angle θ is calculated, and Pd estimated by Equation 6 Y and Equation 3 to calculate the formed angle Φ. This enables the position estimation unit 325 to estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 with higher accuracy.

[0120] In the above-described example, the parameter calculation unit 321 sets the value indicated by the reliability parameter as the weight parameter, but the weight parameter is not limited to this example. Hereinafter, with reference to Figs. 6 and 7, another example of a method for calculating a weight parameter by the parameter calculation unit 321 will be described. First, with reference to Fig. 6, a specific example of a method for calculating a weight parameter in a case where the smaller the value of the reliability parameter, the higher the reliability is will be described. In addition, in the following description, a method for calculating a weight parameter based on the reliability parameter of an antenna pair of antennas 221A and 221B will be described.

[0121] 6A is an explanatory diagram for explaining an example of a method for calculating a weight parameter according to a first specified value. The parameter calculation unit 321 may calculate the weight parameter W based on, for example, the reliability parameter Rp and Equation 7. W=1 (Rp <TH) W=0 (Rp≧TH) (Formula 7)

[0122] The parameter calculation unit 321 calculates, for example, a reliability parameter Rp AB is equal to or greater than the specified value TH, a first value is calculated, and a reliability parameter Rp AB is less than the specified value TH, the second value may be calculated.

[0123] The first value may be, for example, "0" as shown in FIG. 6A. The second value may be, for example, "1" as shown in FIG. 6A. However, the first value and the second value may be any value as long as the first value is smaller than the second value. This allows the parameter calculation unit 321 to set the weight parameter by a simpler calculation method.

[0124] Moreover, the parameter calculation unit 321 may calculate a first value when the reliability parameter Rp is equal to or greater than a first specified value, and may calculate a second value when the reliability parameter Rp is less than a second specified value that is smaller than the first specified value. Furthermore, the parameter calculation unit 321 may calculate a third value using a specified function when the reliability parameter Rp is equal to or greater than the second specified value and less than the first specified value. Here, the specified function may be, for example, a monotonically increasing or monotonically decreasing function. In this case, when the reliability is higher as the reliability parameter is smaller, the specified function is a monotonically decreasing function, and when the reliability is higher as the reliability parameter is larger, the specified function is a monotonically increasing function. First, a specific example of a method for calculating a weight parameter when the specified function is a monotonically decreasing function will be described with reference to FIG. 6B to FIG. 6D.

[0125] 6B is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a linear function as a prescribed function. The parameter calculation unit 321 may calculate the weight parameter W based on the reliability parameter Rp and Equation 8. W=1 (Rp <TH2) W=―(Rp AB -TH2) / (TH1-TH2)+1 (TH2≦Rp <TH1) W=0 (Rp≧TH1) (Formula 8)

[0126] The parameter calculation unit 321 calculates the reliability parameter Rp ABis equal to or greater than the first specified value TH1, the parameter calculation unit 321 calculates a first value of "0", and if it is less than the second specified value, the parameter calculation unit 321 calculates a second value of "1". AB is equal to or greater than the second specified value TH2 and less than the first specified value TH1, the third value may be calculated using a linear function as the specified function.

[0127] 6C is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a trigonometric function as a prescribed function. The parameter calculation unit 321 may calculate the weight parameter W based on the reliability parameter Rp and Equation 9. W=1 (Rp <TH2) W = cos[(Rp AB -TH2) / (TH1-TH2)×π / 2 (TH2≦Rp <TH1) W=0 (Rp≧TH1) (Equation 9)

[0128] The parameter calculation unit 321 calculates the reliability parameter Rp AB is equal to or greater than the first specified value TH1, the parameter calculation unit 321 calculates a first value of "0", and if it is less than the second specified value, the parameter calculation unit 321 calculates a second value of "1". AB is equal to or greater than the second specified value TH2 and less than the first specified value TH1, the third value may be calculated using a trigonometric function as the specified function.

[0129] 6D is an explanatory diagram for explaining an example of a method for calculating a weight parameter using an exponential function as a prescribed function. The parameter calculation unit 321 may calculate the weight parameter W based on the reliability parameter Rp and Equation 10. W=1 (Rp <TH2) W = exp[―5×(Rp AB -TH2) / (TH1-TH2)] (TH2≦Rp <TH1) W=0 (Rp≧TH1) (Equation 10)

[0130] The parameter calculation unit 321 calculates the reliability parameter Rp AB is equal to or greater than the first specified value TH1, the parameter calculation unit 321 calculates a first value of "0", and if it is less than the second specified value, the parameter calculation unit 321 calculates a second value of "1". AB is equal to or greater than the second specified value TH2 and less than the first specified value TH1, the third value may be calculated using an exponential function as the specified function.

[0131] A specific example of the method for calculating the weighting parameters in the case where the smaller the reliability parameter Rp, the higher the reliability is described above. Next, a specific example of the method for calculating the weighting parameters in the case where the larger the reliability parameter Rp, the higher the reliability is described with reference to FIG.

[0132] 7A is an explanatory diagram for explaining an example of a method for calculating a weight parameter according to a first specified value. The parameter calculation unit 321 may calculate the weight parameter W based on the reliability parameter Rp and Equation 11. W=0 (Rp <TH) W=1 (Rp≧TH) (Formula 11)

[0133] The parameter calculation unit 321 calculates the reliability parameter Rp AB is equal to or greater than the specified value TH, a first value is calculated, and a reliability parameter Rp AB is less than the specified value TH, the second value may be calculated.

[0134] In addition, in Equation 7, the first value may be any value as long as it is smaller than the second value, but in Equation 11, the first value may be any value as long as it is larger than the second value. The first value may be, for example, "1" as shown in FIG. 7A. Also, the second value may be, for example, "0" as shown in FIG. 7A.

[0135] That is, in the case where the reliability is higher as the reliability parameter is larger, the magnitude relationship between the first value and the second value described in the case where the reliability is higher as the reliability parameter is smaller is reversed. With reference to the following Figures 7B to 7D, a specific example of a method for calculating a weight parameter when the specified function is a monotonically increasing function will be described, but descriptions that overlap with the contents described with reference to Figures 6B to 6D will be omitted.

[0136] 7B is an explanatory diagram for explaining an example of a method for calculating a weighting parameter using a linear function as a prescribed function. The parameter calculation unit 321 may calculate the weighting parameter W based on the reliability parameter Rp and Equation 12. W=0 (Rp <TH2) W=(Rp AB -TH2) / (TH1-TH2)+1 (TH2≦Rp <TH1) W=1 (Rp≧TH1) (Formula 12)

[0137] 7C is an explanatory diagram for explaining an example of a method for calculating a weight parameter using a trigonometric function as a prescribed function. The parameter calculation unit 321 may calculate the weight parameter W based on the reliability parameter Rp and Equation 13. W=0 (Rp <TH2) W = sin[(Rp AB -TH2) / (TH1-TH2)×π / 2 (TH2≦Rp <TH1) W=1 (Rp≧TH1) (Equation 13)

[0138] 7D is an explanatory diagram for explaining an example of a method for calculating a weight parameter using an exponential function as a prescribed function. The parameter calculation unit 321 may calculate the weight parameter W based on the reliability parameter Rp and Equation 14. W=0 (Rp <TH2) W = exp[5×(Rp AB -TH2) / (TH1-TH2)-1] (TH2≦Rp <TH1) W=1 (Rp≧TH1) (Formula 14)

[0139] The parameter calculation unit 321 calculates the weighting parameters for each antenna pair by using at least one of the specific examples of the weighting parameter calculation method. Then, the position estimation unit 325 estimates the phase difference Pd X and the phase difference between the antennas in the Y-axis direction Pd Y Furthermore, the position estimation unit 325 calculates the phase difference Pd X and Pd Y and calculates the angles θ and Φ between the signals as the arrival angles of the signals based on Equation 3. This enables the position estimation unit 325 to reduce the influence of a multipath environment and to calculate the arrival angles of the signals with higher accuracy.

[0140] (Example of operation processing) 8 is an explanatory diagram for explaining an example of an operation process of the system 1 according to the first embodiment. First, the communication unit 120 included in the portable device 100 transmits a Poll signal, and the communication unit 220 included in the vehicle-mounted device 200 receives the Poll signal (S201).

[0141] Next, the communication unit 220 transmits a Resp signal in response to the Poll signal, and the communication unit 120 receives the Resp signal (S203).

[0142] Then, the communication unit 120 transmits a Final signal in response to the Resp signal, and the communication unit 220 receives the Final signal (S205). Here, the communication unit 220 transmits various information related to the signals transmitted and received between the communication unit 120 and the communication unit 310 included in the control device 300.

[0143] Next, the position estimation unit 325 calculates a distance measurement value based on the signals transmitted and received between the portable device 100 and the vehicle-mounted device (S207).

[0144] Next, the parameter calculation unit 321 calculates a reliability parameter based on the signal received by the vehicle-mounted device 200 (S209).

[0145] Furthermore, the parameter calculation unit 321 calculates a weighting parameter based on the calculated reliability parameter (S211).

[0146] Then, the position estimation unit 325 performs weighted averaging on the phase differences between the antennas using the weighting parameters calculated by the parameter calculation unit 321 (S213).

[0147] Next, the position estimation unit 325 estimates the angle of arrival of the signal received from the portable device 100 using the weighted averaged phase difference between the antennas (S215).

[0148] Then, the position estimation unit 325 calculates the three-dimensional position of the portable device 100 based on the estimated signal arrival angle and the distance measurement value (S217).

[0149] Then, the control unit 320 determines whether or not the three-dimensional position of the portable device 100 calculated by the position estimation unit 325 satisfies a predetermined criterion (S219). If the predetermined criterion is satisfied (S219: Yes), the control unit 320 proceeds to S221, and if the predetermined criterion is not satisfied (S219: No), the control unit 320 ends the process.

[0150] When the predetermined criterion is satisfied (S219: Yes), the control unit 320 performs operational control relating to starting or stopping the engine, which is an example of the operating device 400 (S221), and the control unit 320 ends the process.

[0151] An example of control according to the first embodiment has been described above. According to the control according to the first embodiment, the control device 300 can reduce the influence of multipath and estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 with higher accuracy. Next, a second embodiment will be described with reference to Figs. 9 to 11.

[0152] <3.2. Second Example> The control unit 320 of the second embodiment applies a weighting parameter based on a reliability parameter calculated based on a signal received by the vehicle-mounted device 200 from the portable device 100 to at least two or more tentative positional relationships estimated based on signals transmitted and received by the vehicle-mounted device 200 and the portable device 100, and performs control to estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200.

[0153] For example, the position estimation unit 325 according to the second embodiment estimates a tentative positional relationship between the portable device 100 and the vehicle-mounted device 200 based on signals transmitted and received between the portable device 100 and each of the antennas 221A, 221B, and 221C as shown in Fig. 2. The position estimation unit 325 according to the second embodiment estimates a tentative positional relationship between the portable device 100 and the vehicle-mounted device 200 based on signals transmitted and received between the portable device 100 and each of the antennas 221A, 221C, and 221D as shown in Fig. 2. The position estimation unit 325 according to the second embodiment estimates a tentative positional relationship between the portable device 100 and the vehicle-mounted device 200 based on signals transmitted and received between the portable device 100 and each of the antennas 221B, 221C, and 221D as shown in Fig. 2.

[0154] In addition, the parameter calculation unit 321 calculates a reliability parameter based on the signal received by the portable device 100 for each antenna or antenna pair of the vehicle-mounted device 200. Furthermore, the parameter calculation unit 321 calculates a weight parameter based on the calculated reliability parameter by using any of the methods described in the first embodiment.

[0155] Then, when the three tentative positional relationships are estimated as described above, the position estimation unit 325 of the second embodiment may apply the weighting parameters described above to the three tentative positional relationships, and estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200.

[0156] Although the case where three tentative positional relationships are estimated has been described, any number of tentative positional relationships may be estimated as long as at least two or more are estimated. Also, the method of estimating the positional relationship between the portable device 100 and the vehicle-mounted device 200 according to the second embodiment is applicable as long as the number of antennas in the vehicle-mounted device 200 is at least three or more.

[0157] Moreover, the first, second and third embodiments are also applicable to a case where a plurality of on-board devices 200 are mounted on the vehicle 20. Hereinafter, the vehicle 20 according to the second and third embodiments will be described with reference to a case where two on-board devices 200 are mounted on the vehicle 20.

[0158] Fig. 9 is a block diagram showing a configuration example of the vehicle 20 according to the second and third embodiments. As shown in Fig. 9, the vehicle 20 is equipped with an on-board device 200-1 and an on-board device 200-2. The vehicle 20 may be equipped with three or more on-board devices 200. In addition, the functional configuration examples of the on-board device 200, the control device 300, and the operating device 400 are the same as those described with reference to Fig. 1, and therefore description thereof will be omitted.

[0159] The control unit 320 of the second embodiment may apply a weighting parameter based on a reliability parameter calculated based on signals received by each of the multiple vehicle-mounted devices 200 from the portable device 100 to a tentative positional relationship between the portable device 100 and the vehicle-mounted device 200 estimated based on signals transmitted and received by each of the multiple vehicle-mounted devices 200 and the portable device 100, thereby performing control to estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200.

[0160] First, signals are transmitted and received between the portable device 100 and the vehicle-mounted device 200-1 and the vehicle-mounted device 200-2, and the control device 300 acquires information related to the signals transmitted and received from the vehicle-mounted device 200-1 and the vehicle-mounted device 200-2.

[0161] Then, the parameter calculation unit 321 calculates a reliability parameter based on the signal received by the vehicle-mounted device 200-1 via the portable device 100. Furthermore, the parameter calculation unit 321 calculates a weight parameter based on the calculated reliability parameter by using any of the methods described in the first embodiment.

[0162] In addition, the parameter calculation unit 321 calculates a reliability parameter based on the signal received by the vehicle-mounted device 200-2 from the portable device 100. Furthermore, the parameter calculation unit 321 calculates a weight parameter based on the calculated reliability parameter by using any of the methods described in the first embodiment.

[0163] Next, the position estimation unit 325 estimates the arrival angle of the signal and the three-dimensional position of the portable device 100 based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-1. Furthermore, the position estimation unit 325 estimates the arrival angle of the signal and the three-dimensional position of the portable device 100 based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-2. Note that the arrival angle of the signal and the three-dimensional position of the portable device 100 estimated for each vehicle-mounted device 200 are specific examples of the provisional positional relationship between the portable device 100 and the vehicle-mounted device 200.

[0164] Then, the position estimation unit 325 applies the weighting parameters calculated by the parameter calculation unit 321 to the estimated tentative positional relationship between the portable device 100 and the vehicle-mounted device 200, and estimates the positional relationship between the portable device 100 and the vehicle-mounted device 200. Hereinafter, a specific example of the second embodiment will be described with reference to FIG.

[0165] Fig. 10 is an explanatory diagram for explaining a control example of the system 1 according to the second embodiment. As shown in Fig. 10, the communication unit 220-1 included in the vehicle-mounted device 200-1 has an antenna 221A-1, an antenna 221B-1, an antenna 221C-1, and an antenna 221D-1. The communication unit 220-2 included in the vehicle-mounted device 200-2 has an antenna 221A-2, an antenna 221B-2, an antenna 221C-2, and an antenna 221D-2.

[0166] When the reception power is used as the reliability parameter, it is assumed that the parameter calculation unit 321 calculates the reliability parameters of the antennas 221A-1, 221B-1, and 221C-1 as "-90 dBm" and the reliability parameter of the antenna 221D-1 as "-105 dBm" as shown in Fig. 10. Next, it is assumed that the parameter calculation unit 321 calculates the reliability parameter of the antenna 221A-2 as "-105 dBm" and the reliability parameters of the antennas 221B-2, 221C-2, and 221D-2 as "-90 dBm".

[0167] In this case, the position estimation unit 325 may estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 based on signals transmitted and received by, for example, three antennas with higher reliability. For example, the position estimation unit 325 may select three antennas 221 in descending order of reliability (for example, the highest received power), and estimate a tentative positional relationship based on signals transmitted and received by the selected antennas 221.

[0168] For example, in the example shown in FIG. 10, the three antennas with high reliability are antenna 221A-1, antenna 221B-1, and antenna 221C-1 of communication unit 220-1, and antenna 221B-2, antenna 221C-2, and antenna 221D-2 of communication unit 220-2.

[0169] The position estimation unit 325 estimates the tentative positional relationship based on, for example, signals transmitted and received by the antennas 221A-1, 221B-1, and 221C-1, and the antenna 121 of the portable device 100. Furthermore, the position estimation unit 325 estimates the tentative positional relationship based on signals transmitted and received by the antennas 221B-2, 221C-2, and 221D-2, and the antenna 121 of the portable device 100.

[0170] Then, the position estimation unit 325 applies a weighting parameter to each estimated provisional positional relationship, and estimates the positional relationship between the portable device 100 and the vehicle-mounted device 200. For example, when the positional relationship between the portable device 100 and the vehicle-mounted device 200 is the three-dimensional position of the portable device 100 relative to the vehicle-mounted device 200, the position estimation unit 325 performs a weighted average on the provisional three-dimensional position of the portable device 100 using Equation 15, and estimates the three-dimensional position of the portable device 100. Here, the provisional three-dimensional position of the portable device 100 estimated based on the signals transmitted and received between the portable device 100 and the vehicle-mounted device 200-1 is set to (x1, y1, z1), and the provisional three-dimensional position of the portable device 100 estimated based on the signals transmitted and received between the portable device 100 and the vehicle-mounted device 200-2 is set to (x2, y2, z2). The average reception power of the vehicle-mounted device 200-1 is set to P1, and the average reception power of the vehicle-mounted device 200-2 is set to P2. X = (P1 x1 + P2 x2) / (P1 + P2) Y = (P1 x y1 + P2 x y2) / (P1 + P2) Z = (P1 × z1 + P2 × z2) / (P1 + P2) (Formula 15)

[0171] Equation 15 is an example of calculating the weighted average when the average value of the reliability parameters (average received powers P1 and P2) is applied as the weight parameter. The weight parameter may be calculated based on the reliability parameters using the equations described in the first embodiment.

[0172] (Example of operation processing) 11 is an explanatory diagram for explaining an example of an operation process of the system 1 according to the second embodiment. First, the communication unit 120 included in the portable device 100 transmits a Poll signal, and the communication unit 220-1 included in the vehicle-mounted device 200-1 and the communication unit 220-2 included in the vehicle-mounted device 200-2 receive the Poll signal (S301).

[0173] Next, the communication units 220-1 and 220-2 transmit Resp signals in response to the Poll signal, and the communication unit 120 receives the Resp signals (S303).

[0174] Then, the communication unit 120 transmits a Final signal in response to the Resp signal, and the communication units 220-1 and 220-2 receive the Final signal (S305). Here, the communication units 220-1 and 220-2 transmit various information related to the transmitted and received signals to the communication unit 310 included in the control device 300.

[0175] Next, the position estimation unit 325 calculates a first distance measurement value based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-1, and calculates a second distance measurement value based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-2 (S307).

[0176] Next, the parameter calculation unit 321 calculates a first reliability parameter based on the signal received by the vehicle-mounted device 200-1, and calculates a second reliability parameter based on the signal received by the vehicle-mounted device 200-2 (S309).

[0177] Furthermore, the parameter calculation unit 321 calculates weighting parameters based on the calculated reliability parameters (S311). For example, the parameter calculation unit 321 calculates a first weighting parameter based on the first reliability parameter, and calculates a second weighting parameter based on the second reliability parameter.

[0178] Then, the position estimation unit 325 estimates the angle of arrival of the first signal based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-1, and estimates the angle of arrival of the second signal based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-2 (S313).

[0179] Next, the position estimation unit 325 estimates a first tentative three-dimensional position of the portable device 100 based on the arrival angle of the first signal, and estimates a second tentative three-dimensional position of the portable device 100 based on the arrival angle of the second signal (S315).

[0180] Then, the position estimation unit 325 performs a weighted average of the first and second tentative three-dimensional positions of the portable device 100 using the first and second weighting parameters, and estimates the three-dimensional position of the portable device 100 (S317).

[0181] Then, the control unit 320 determines whether or not the three-dimensional position of the portable device 100 estimated by the weighted average satisfies a predetermined criterion (S319). If the predetermined criterion is satisfied (S319: Yes), the control unit 320 advances the process to S321, and if the predetermined criterion is not satisfied (S319: No), the control unit 320 ends the process.

[0182] When the predetermined criterion is met (S319: Yes), the control unit 320 performs operational control relating to starting or stopping the engine, which is an example of the operating device 400 (S321), and the control unit 320 ends the process.

[0183] The above describes the control example according to the second embodiment. According to the control according to the first embodiment, the control device 300 can reduce the influence of multipath and estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 with higher accuracy.

[0184] In the first and second embodiments, the position estimation unit 325 calculates two weighting parameters based on the signals transmitted and received by the vehicle-mounted device 200-1 and the vehicle-mounted device 200-2, and applies the two weighting parameters to the calculation process and the calculation result of the positional relationship between the portable device 100 and the vehicle-mounted device 200. In this way, the use of weighting parameters based on the reliability parameters can reduce the influence of calculation errors caused by the multipath environment. The control unit 320 may select the vehicle-mounted device 200 that is less affected by the multipath environment based on the reliability parameters transmitted and received by the vehicle-mounted device 200-1 and the vehicle-mounted device 200-2. Hereinafter, the third embodiment will be described with reference to Figs. 12 to 14.

[0185] <3.3. Third Example> 12 is an explanatory diagram for explaining a control example of the system 1 according to the third embodiment. The control unit 320 according to the third embodiment compares each of the reliability parameters calculated based on the signal received by each of the multiple vehicle-mounted devices 200 from the portable device 100, and performs control to estimate the positional relationship based on the signal transmitted and received between the vehicle-mounted device 200 that transmitted a signal that is more appropriate as a processing target for estimating the positional relationship and the portable device 100. In the following description, the reliability parameter is described as the reception power of the signal received by the antenna 221, but may be another reliability parameter as described above.

[0186] For example, antenna 221A-1, antenna 221B-1, antenna 221C-1, and antenna 221D-1 of communication unit 220-1 included in in-vehicle device 200-1 receive a Final signal from antenna 121 of communication unit 120 included in portable device 100. Here, it is assumed that the reception power of antenna 221A-1 is "-90 dBm", the reception power of antenna 221B-1 is "-95 dBm", the reception power of antenna 221C-1 is "-95 dBm", and the reception power of antenna 221D-1 is "-100 dBm".

[0187] Furthermore, antenna 221A-2, antenna 221B-2, antenna 221C-2, and antenna 221D-2 of communication unit 220-2 included in in-vehicle device 200-2 receive a Final signal from antenna 121 of communication unit 120 included in portable device 100. Here, it is assumed that the reception power of antenna 221A-2 is "-99 dBm", the reception power of antenna 221B-2 is "-99 dBm", the reception power of antenna 221C-2 is "-101 dBm", and the reception power of antenna 221D-2 is "-101 dBm".

[0188] In this case, the parameter calculation unit 321 calculates a basic statistic based on the reliability parameter (for example, received power) estimated for each antenna. The basic statistic may be, for example, an average value, a maximum value, a minimum value, or a median value.

[0189] For example, when averaging the basic statistics, the parameter calculation unit 321 may calculate "-95 dBm" as the average value of the reception power of the antennas 221A-1, 221B-1, 221C-1, and 221D-1. The parameter calculation unit 321 may also calculate "-100 dBm" as the average value of the reception power of the antennas 221A-2, 221B-2, 221C-2, and 221D-2.

[0190] Then, the position estimation unit 325 compares the average value of the received power of antenna 221A-1, antenna 221B-1, antenna 221C-1 and antenna 221D-1, which is "-95 dBm," with the average value of the received power of antenna 221A-2, antenna 221B-2, antenna 221C-2 and antenna 221D-2, which is "-100 dBm."

[0191] Then, the position estimation unit 325 selects a communication unit 220 that is more appropriate (i.e., has high reliability) as a processing target for estimating the positional relationship. For example, the position estimation unit 325 may estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200-1 based on a signal transmitted and received between the communication unit 220-1 having the antenna 221-1 with a larger average value of received power and the communication unit 120 included in the portable device 100.

[0192] The position estimation unit 325 may select three antennas out of four or more antennas in each of the multiple vehicle-mounted devices 200 based on the reliability parameters. Then, the position estimation unit 325 may compare the reliability parameters calculated based on the signals received by each of the selected three antennas. Then, the position estimation unit 325 may estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 based on the signal transmitted and received between the vehicle-mounted device 200 that has received a signal that is more appropriate as a processing target for estimating the positional relationship based on the result of the comparison, and the portable device 100.

[0193] 13 is an explanatory diagram for explaining another control example of the system 1 according to the third embodiment. For example, the antenna 221A-1, the antenna 221B-1, the antenna 221C-1, and the antenna 221D-1 of the communication unit 220-1 included in the vehicle-mounted device 200-1 receive a Final signal from the antenna 121 of the communication unit 120 included in the portable device 100. Here, it is assumed that the reception power of the antenna 221A-1 is "-89 dBm", the reception power of the antenna 221B-1 is "-89 dBm", the reception power of the antenna 221C-1 is "-89 dBm", and the reception power of the antenna 221D-1 is "-105 dBm". In this case, the position estimation unit 325 may select the antenna 221A-1, the antenna 221B-1, and the antenna 221C-1 in descending order of reception power.

[0194] Also, the antenna 221A-2, the antenna 221B-2, the antenna 221C-2, and the antenna 221D-2 of the communication unit 220-2 included in the vehicle-mounted device 200-2 receive a Final signal from the antenna 121 of the communication unit 120 included in the portable device 100. Here, it is assumed that the reception power of the antenna 221A-2 is "-105 dBm", the reception power of the antenna 221B-2 is "-90 dBm", the reception power of the antenna 221C-2 is "-90 dBm", and the reception power of the antenna 221D-2 is "-90 dBm". In this case, the position estimation unit 325 may select the antennas 221B-2, 221C-2, and 221D-2 in descending order of reception power.

[0195] In addition, if each of the multiple vehicle-mounted devices 200 has N antennas (4≦N), the position estimation unit 325 may select M antennas (3≦M≦N) from the N antennas in each of the multiple vehicle-mounted devices 200 based on the reliability parameter.

[0196] Next, the position estimation unit 325 compares the reliability parameters calculated based on the signals received by each of the three antennas selected in each of the vehicle-mounted devices 200-1 and 200-2.

[0197] When the comparison method is the average reliability parameter values ​​of each antenna 221, the position estimation unit 325 obtains a comparison result that antenna 221A-1, antenna 221B-1, and antenna 221C-1 of the vehicle-mounted unit 200-1 have greater average received power than antenna 221B-2, antenna 221C-2, and antenna 221D-2 of the vehicle-mounted unit 200-2, and have transmitted and received signals that are more suitable as targets for processing to estimate the position relationship.

[0198] Then, the position estimation unit 325 executes a process of estimating the positional relationship between the portable device 100 and the in-vehicle device 200-1 based on a signal transmitted and received between the in-vehicle device 200-1, which has transmitted and received a signal that is more appropriate as a processing target for estimating the positional relationship, and the portable device 100. Note that the positional relationship between the portable device 100 and the in-vehicle device 200-1 may be the arrival angle of the signal, or may be a two-dimensional or three-dimensional position of the portable device 100, as in the first and second embodiments.

[0199] The position estimation unit 325 may select an antenna from each of the multiple vehicle-mounted devices 200, whose reliability parameter based on a received signal satisfies a specified standard, among the four or more antennas each of the multiple vehicle-mounted devices 200 has. For example, the position estimation unit 325 may select an antenna from each of the multiple vehicle-mounted devices 200, whose reliability parameter based on a received signal is a predetermined value, among the four or more antennas each of the multiple vehicle-mounted devices 200 has. More specifically, for example, if the reliability parameter is a received power and the predetermined value is −90 dBm, the position estimation unit 325 may select an antenna from the four or more antennas, whose received signal has a received power of −90 dBm or more. Then, the position estimation unit 325 may compare the reliability parameters of the antennas selected from each of the multiple vehicle-mounted devices 200.

[0200] (Example of operation processing) 14 is an explanatory diagram for explaining an example of operation processing of the system 1 according to the third embodiment. In the following explanation, the operation processing will be explained in the case where the smaller the value of the reliability parameter, the higher the reliability of the transmitted and received signal. First, the communication unit 120 included in the portable device 100 transmits a Poll signal, and the communication unit 220-1 included in the vehicle-mounted device 200-1 and the communication unit 220-2 included in the vehicle-mounted device 200-2 receive the Poll signal (S401).

[0201] Next, the communication unit 220-1 and the communication unit 220-2 transmit a Resp signal in response to the Poll signal, and the communication unit 120 receives the Resp signal (S403).

[0202] Then, the communication unit 120 transmits a Final signal in response to the Resp signal, and the communication units 220-1 and 220-2 receive the Final signal (S405). Here, the communication units 220-1 and 220-2 transmit various information related to the transmitted and received signals to the communication unit 310 included in the control device 300.

[0203] Next, the position estimation unit 325 calculates a first distance measurement value based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-1, and calculates a second distance measurement value based on the signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-2 (S407).

[0204] Next, the parameter calculation unit 321 calculates a first reliability parameter based on the signal received by the vehicle-mounted device 200-1, and calculates a second reliability parameter based on the signal received by the vehicle-mounted device 200-2 (S409).

[0205] Then, the control unit 320 judges whether the reliability parameter based on the signal received by the vehicle-mounted device 200-1 is greater than the reliability parameter based on the signal received by the vehicle-mounted device 200-2 (S413). If the reliability parameter based on the signal received by the vehicle-mounted device 200-1 is greater (S413: Yes), the control unit 320 proceeds to S415, and if the reliability parameter based on the signal received by the vehicle-mounted device 200-2 is greater (S413: No), the control unit 320 proceeds to S419.

[0206] If the reliability parameter based on the signal received by the vehicle-mounted device 200-1 is greater (S413: Yes), the position estimation unit 325 estimates the arrival angle of the signal based on the signal transmitted and received by the communication unit 220-2 provided in the vehicle-mounted device 200-2 (S415).

[0207] Then, the position estimation unit 325 estimates the three-dimensional position of the portable device 100 based on the estimated arrival angle of the signal and the second distance measurement value (S417).

[0208] If the reliability parameter based on the signal received by the vehicle-mounted device 200-2 is greater (S413: No), the position estimation unit 325 estimates the arrival angle of the signal based on the signal transmitted and received by the communication unit 220-1 provided in the vehicle-mounted device 200-1 (S419).

[0209] Then, the position estimation unit 325 estimates the three-dimensional position of the portable device 100 based on the estimated arrival angle of the signal and the second distance measurement value (S421).

[0210] Then, the control unit 320 determines whether or not the estimated three-dimensional position of the portable device 100 satisfies a predetermined criterion (S423). If the predetermined criterion is satisfied (S423: Yes), the control unit 320 advances the process to S425, and if the predetermined criterion is not satisfied (S423: No), the control unit 320 ends the process.

[0211] When the predetermined criterion is satisfied (S423: Yes), the control unit 320 performs operational control relating to starting or stopping the engine, which is an example of the operating device 400 (S425), and the control unit 320 ends the process.

[0212] An example of the operation process of the system 1 according to the third embodiment has been described above. Note that the operation process when there are a plurality of vehicle-mounted devices 200 is not limited to the example. For example, after the Poll signal, the Resp signal, and the Final signal are transmitted and received between the communication unit 120 of the portable device 100 and the communication unit 220-1 of the vehicle-mounted device 200-1, the Poll signal, the Resp signal, and the Final signal may be transmitted and received between the communication unit 120 and the communication unit 220-2 of the vehicle-mounted device 200-2. In addition, the position estimation unit 325 may estimate a first three-dimensional position of the portable device 100 based on a signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-1, and may estimate a second three-dimensional position of the portable device 100 based on a signal transmitted and received between the portable device 100 and the vehicle-mounted device 200-2, and then the control unit 320 may compare the reliability parameters. For example, when the control unit 320 determines that the vehicle-mounted device 200-1 has transmitted and received a more reliable signal than the vehicle-mounted device 200-2, the control unit 320 may determine the first three-dimensional position as the three-dimensional position of the portable device 100.

[0213] According to the control of the third embodiment described above, the control device 300 can estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 with higher accuracy by selecting the vehicle-mounted device 200 that is less affected by multipath.

[0214] Although the first, second and third examples have been described in detail, the control device 30 according to this embodiment may perform control by combining the above-mentioned first example with either the second or third example.

[0215] In a case where the first embodiment and the second embodiment are combined, for example, the position estimation unit 325 performs weighted averaging on the inter-antenna phase difference of the antenna pair of the vehicle-mounted device 200-1 using a weighting parameter based on the reliability parameter. Then, the position estimation unit 325 estimates the arrival angle of the signal and the provisional three-dimensional position of the portable device 100 based on the inter-antenna phase difference for which the weighted average has been performed. Furthermore, the position estimation unit 325 estimates the arrival angle of the signal and the provisional three-dimensional position of the portable device 100 by a similar process also in the vehicle-mounted device 200-2. Then, the position estimation unit 325 may perform weighted averaging on the estimated provisional three-dimensional positions of the two portable devices 100 based on the reliability parameter to estimate the three-dimensional position of the portable device 100.

[0216] In the case of combining the first embodiment and the third embodiment, for example, the position estimation unit 325 compares the reliability parameters of the vehicle-mounted device 200-1 and the vehicle-mounted device 200-2, and selects the vehicle-mounted device 200 for estimating the positional relationship with the portable device 100 according to the result of the comparison. Next, the position estimation unit 325 performs weighted averaging using a weight parameter based on the reliability parameter for the inter-antenna phase difference of the antenna pair of the selected vehicle-mounted device 200. Then, the position estimation unit 325 may estimate the arrival angle of the signal and the three-dimensional position of the portable device 100 based on the inter-antenna phase difference for which the weighted average has been performed.

[0217] By controlling the combination of the first embodiment of the present embodiment described above with either the second embodiment or the third embodiment, the control device 30 can estimate the positional relationship between the portable device 100 and the vehicle-mounted device 200 with higher accuracy.

[0218] <<4. Supplementary Information>> Although the preferred embodiment of the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is clear that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally belong to the technical scope of the present invention.

[0219] For example, the series of processes performed by each device described in this specification may be realized using software, hardware, or a combination of software and hardware. The programs constituting the software are stored in advance, for example, in a recording medium (non-transitory medium) provided inside or outside each device. Then, each program is loaded into a RAM when executed by a computer, for example, and executed by a processor such as a CPU. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, etc. Also, the computer program may be distributed, for example, via a network, without using a recording medium.

[0220] In addition, the steps in the processing of the operation of the system 1 according to the present embodiment do not necessarily have to be processed in chronological order according to the order described in the explanatory diagram. For example, each step in the processing of the operation of the system 1 may be processed in an order different from the order described in the explanatory diagram, or may be processed in parallel. [Explanation of symbols]

[0221] 1: system, 100: portable device, 110: control unit, 120: communication unit, 121: antenna, 20: vehicle, 200: vehicle-mounted device, 210: control unit, 220: communication unit, 221: antenna, 300: control device, 310: communication unit, 320: control unit, 321: parameter calculation unit, 325: position estimation unit, 400: operating device

Claims

1. a control unit that performs control to estimate a positional relationship between a communication device having at least three or more antennas and another communication device based on a signal transmitted and received between the communication device and the other communication device; Equipped with The control unit is applying a weighting parameter based on a reliability parameter, which is an index indicating the degree of suitability of the communication device as a processing target for estimating a positional relationship between the communication device and the other communication device, calculated based on the signal received by the communication device from the other communication device, to tentative positional relationships between at least two or more of the communication devices and the other communication devices estimated based on the signals transmitted and received by the communication device and the other communication devices, and performing control to estimate the positional relationship between the communication device and the other communication devices; The weighting parameter indicates a first value when the reliability parameter is equal to or greater than a first specified value, indicates a second value when the reliability parameter is less than a second specified value that is smaller than the first specified value, and indicates a third value calculated by a specified function when the reliability parameter is in a range equal to or greater than the second specified value and less than the first specified value.

2. The control unit is applying a weighting parameter based on the reliability parameter calculated based on the signal received by each of the plurality of communication devices from the other communication devices to the tentative positional relationship estimated based on the signal transmitted and received by each of the plurality of communication devices and the other communication devices, and performing control to estimate a positional relationship between the communication device and the other communication devices; The control device according to claim 1 .

3. The control unit is performing a weighted average of the tentative positional relationships estimated between the plurality of communication devices and the other communication devices using each of the weight parameters based on the signals received by each of the plurality of communication devices from the other communication devices, and performing control to estimate the positional relationship between the communication device and the other communication devices; The control device according to claim 2.

4. the three or more antennas of the communication device are four or more antennas, The control unit is applying the weighting parameters to the tentative positional relationship estimated based on signals transmitted and received by three or more antennas that are appropriate as processing targets for estimating the positional relationship based on the reliability parameter among the four or more antennas, and performing control to estimate a positional relationship between the communication device and the other communication device; The control device according to claim 2 or 3.

5. The control unit is performing control to estimate a three-dimensional position of the other communication device as a positional relationship between the plurality of communication devices and the other communication device based on signals transmitted and received between the plurality of communication devices and the other communication device; The control device according to any one of claims 2 to 4.

6. The defined function is a monotonically increasing or decreasing function. The control device according to claim 5.

7. The defined function is a linear function. The control device according to claim 6.

8. The defined function is a trigonometric function. The control device according to claim 6.

9. The defined function is an exponential function. The control device according to claim 6.

10. the first value is either 0 or 1; the second value being the other of 0 or 1; The control device according to claim 1.

11. The reliability parameter includes at least one of an index indicating the magnitude of noise in a signal received by at least one of the communication device and the other communication device, and an index indicating the validity that the signal is due to a direct wave. A control device according to any one of claims 1 to 10.

12. The communication device is mounted on a moving object. A control device according to any one of claims 1 to 11.

13. The other communication device is carried by a user who uses the mobile object. The control device according to claim 12.

14. The signal includes a radio signal conforming to ultra-wideband wireless communication. A control device according to any one of claims 1 to 13.

15. A communication device having at least three antennas; Another communication device having at least one antenna; a control device that performs control to estimate a positional relationship between the communication device and the other communication device based on a signal transmitted and received between the communication device and the other communication device; Equipped with The control device includes: applying a weighting parameter based on a reliability parameter, which is an index indicating the degree of suitability of the communication device as a processing target for estimating a positional relationship between the communication device and the other communication device, calculated based on the signal received by the communication device from the other communication device, to tentative positional relationships between at least two or more of the communication devices and the other communication devices estimated based on the signals transmitted and received by the communication device and the other communication devices, and performing control to estimate the positional relationship between the communication device and the other communication devices; The weight parameter indicates a first value when the reliability parameter is greater than or equal to a first specified value, indicates a second value when the reliability parameter is less than a second specified value that is smaller than the first specified value, and indicates a third value calculated by a specified function in the range between the second specified value and less than the first specified value.

16. Transmitting and receiving signals between a communication device having at least three or more antennas and another communication device; performing control to estimate a positional relationship between the communication device and the other communication device based on the transmitted and received signals; Including, The control for estimating a positional relationship between the communication device and the other communication device is applying a weighting parameter based on a reliability parameter, which is an index indicating the degree of suitability of the communication device as a processing target for estimating a positional relationship between the communication device and the other communication devices, calculated based on the signal received by the communication device from the other communication devices, to tentative positional relationships between at least two or more of the communication devices and the other communication devices estimated based on the signals transmitted and received by each of the communication devices and the other communication devices, and performing control to estimate the positional relationship between the communication device and the other communication devices; Including, a control method executed by a computer, wherein the weight parameter indicates a first value when the reliability parameter is equal to or greater than a first specified value, indicates a second value when the reliability parameter is less than a second specified value that is smaller than the first specified value, and indicates a third value calculated by a specified function when the reliability parameter is in a range equal to or greater than the second specified value and less than the first specified value.

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