JP2005249623A - Vehicle-mounted radar system and control method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle-mounted radar system and a control method for the same allowing reduction in the power consumption of a radar system by controlling transmission of a radar signal on the basis of the traveling conditions of a vehicle. <P>SOLUTION: The vehicle-mounted radar system comprises a signal transmitting section transmitting a radar signal, a signal receiving section receiving the radar signal, and a signal processing section processing the radar signal received by the signal receiving section. The signal processing section has a function for judging whether the vehicle is in the stationary state by detecting relative velocity concerning the vehicle and the ground from the received radar signal. When judged that the vehicle is in the stationary state, the transmission of the radar signal by the signal transmitting section is ceased. When judged that the vehicle is in the traveling state, the transmission of the radar signal by the signal transmitting section is resumed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an on-vehicle radar device.

  In recent years, radar devices for vehicles, particularly automobiles, have been installed to measure distance and relative speed with the preceding vehicle, and issue an inter-vehicle distance alarm based on the measurement results, or to track the preceding vehicle. A system that controls the system is attracting attention.

  On the other hand, devices mounted on vehicles tend to increase mainly in information devices, and accordingly, power consumption as a whole vehicle tends to increase. Therefore, it is important to reduce the power consumption of each installed device.

  As a method for reducing power consumption of an in-vehicle radar device, for example, in Japanese Patent Laid-Open No. 2002-228745, a signal processing period that does not require a radar reception signal and a waiting period that waits for a reflected wave signal include a transmission antenna and It has been proposed to reduce the power consumption and heat generation of the entire device by limiting the switching operation in the switch circuit that switches the connection state with the receiving antenna.

JP 2002-228745 A

  The technology described in Japanese Patent Laid-Open No. 2002-228745 is a switch circuit that switches a connection state between a transmission antenna and a reception antenna during a signal processing period that does not require a radar reception signal and a standby period during which a reflected wave signal is waited. The power consumption and heat generation of the entire device are reduced by restricting the switching operation in the vehicle, and no consideration is given to the running state of the vehicle.

  An object of the present invention is to provide an in-vehicle radar device and a control method thereof that can suppress power consumption of the in-vehicle radar device by controlling the transmission of radar signals based on the running state of the vehicle.

  In order to achieve the above object, in the present invention, a vehicle-mounted apparatus including a signal transmission unit that transmits a radar signal, a signal reception unit that receives the radar signal, and a signal processing unit that processes the radar signal received by the reception unit. A radar device, wherein the signal processing unit detects a relative speed between the vehicle and the ground from the received radar signal and determines whether or not the vehicle is in a stopped state. Further, the signal processing unit includes a gyro Alternatively, a function of determining the traveling state of the vehicle based on a signal from the yaw rate sensor is provided.

  And when it determines with a vehicle being in a stop state, transmission of the radar signal of the said signal transmission part is stopped.

  Alternatively, when it is determined that the vehicle is in a stopped state, the transmission of the radar signal of the signal transmission unit is stopped. After that, when it is determined that the vehicle is in a traveling state, the radar signal of the signal transmission unit Resume sending.

  Thus, by controlling the transmission of the radar signal based on the running state of the vehicle, the power consumption of the in-vehicle radar device can be suppressed.

  In addition, the on-vehicle radar device of the present invention includes a gyro or yaw rate sensor, so that there is no need to wrap around the harness.

  ADVANTAGE OF THE INVENTION According to this invention, the vehicle-mounted radar apparatus which can suppress the power consumption of a vehicle-mounted radar apparatus by controlling transmission of a radar signal based on the driving | running | working state of a vehicle, and its control method can be provided.

  The in-vehicle radar device detects the relative speed between the host vehicle and the ground using the component of the radio wave reflected from the road, and detects the stop of the host vehicle when the relative speed is zero. By detecting the stop, the power supply circuit that supplies a bias to the amplifier circuit of the signal transmission unit that transmits the radar signal of the in-vehicle radar device is controlled so that the amplifier circuit is not operated.

  In addition, the fact that the host vehicle has changed from the stopped state to the running state indicates that the in-vehicle radar device is in an operating state by restarting the bias supply to the amplifier circuit based on the yaw rate sensor provided in the in-vehicle radar device or the change in the output of the gyro. To.

  As described above, when the vehicle is stopped, the transmission power can be stopped or reduced, and the power consumption of the in-vehicle radar device can be suppressed.

  Embodiment 1 of an on-vehicle radar device according to the present invention will be described below.

  FIG. 1 shows the configuration of an in-vehicle radar device 1 according to the present invention. The in-vehicle radar device 1 includes a signal processing unit 10, a gyro 11, a power supply circuit 13, and a front end 14.

  First, the front end 14 and the signal processing unit 10 that are involved in the detection of the distance, relative speed, and angle with the forward detection object, which are basic functions of the in-vehicle radar device, will be described.

  A detailed configuration of the front end 14 is shown in FIG. The front end 14 includes a signal transmission unit 20 and a signal reception unit 21. The signal transmission unit 20 generates a high frequency by the oscillation circuit 201 and transmits a radar signal forward through the transmission antenna 203 with the high frequency amplified by the amplification circuit 202. The radar signal hits an object ahead and is reflected, and the signal receiving unit 21 captures the radar signal via the receiving antennas 210 and 211.

  At this time, the frequency of the radar signal received by the receiving antennas 210 and 211 is a value shifted by a relative speed difference with respect to the forward detection object with respect to the radar signal transmitted from the transmitting antenna 203 due to the Doppler effect. .

The down converters 212 and 213 have a function of extracting only the shifted frequency from the frequency of the transmitted radar signal and the frequency of the received radar signal, and the extracted signals are used as IF signals 214 and 215. Sent to the signal processor 10 (IF:
Intermediate Frequency). Then, after A / D conversion is performed by the signal processing unit 10, the distance, relative speed, and angle are calculated by an internal microcomputer. That is, a radar signal is transmitted from the signal transmission unit 20 in the front end 14, the radar signal that is a bounce from the front detection object is converted into an IF signal by the signal reception unit 21, and the signal processing unit 10 is a distance from the IF signal. , Relative speed and angle are calculated.

  In the signal receiving unit 21, the number of receiving antennas and down converters is two, depending on the distance and angle calculation algorithm performed by the signal processing unit 10. It can also be composed of pieces.

  Further, the oscillator 201, the amplifier circuit 202, and the down converters 212 and 213 are formed as a chip, and a bias for driving each IC can be supplied.

  Next, a method of detecting the relative speed between the host vehicle and the ground using reflected waves from the road and detecting the stop of the host vehicle when the relative speed is zero will be described.

  FIG. 3 shows an outline of the radar signal transmitted from the vehicle on which the in-vehicle radar device 1 is mounted and the radar signal reflected by the detected object. The radar signal transmitted from the in-vehicle radar device 1 is received by the signal receiving unit as a radar signal having two components: a reflected radar signal from a front detection object and a reflected radar signal from the ground.

  That is, a spectrum as shown in FIG. 4 can be observed. If there is no detected object ahead, the radar signal has only a reflection component from the ground. In any case, the reflected radar signal from the ground can always be detected as a received radar signal as long as there is a relative speed difference between the ground and the host vehicle. The spectrum of the reflected radar signal from the ground moves to the lower frequency side as the relative speed difference from the ground becomes smaller, that is, as the speed of the host vehicle becomes slower, and the relative speed is reduced by stopping the host vehicle. 0.

  Therefore, it is possible to detect that the host vehicle is stopped by monitoring the component of the reflected radar signal from the ground. Further, the in-vehicle radar device described in the first embodiment is not intended to detect the speed of the own vehicle, but is intended to detect whether the own vehicle is in a stopped state. The calculation can be simplified.

The above vehicle stop detection method is recognized by the signal processing unit 10 shown in FIG. 1 performing signal processing. The signal processing unit 10 instructs the power supply circuit 13 to change the bias value for the signal transmission unit 20 when the host vehicle stops. Specifically, in the front end 14 shown in FIG. 2, the amplification circuit drive bias value to the amplification circuit 202 is changed, and the operation of the amplification circuit 202 is stopped. MMIC (Monolithic Microwave Integrated) such as amplifier circuit 202
A circuit (monolithic microwave integrated circuit) is composed of an FET (Field-Effect Transistor), and the operation of the amplifier circuit 202 is stopped by lowering the gate bias voltage of the FET to the pinch-off region. Can do.

  Since the amplifier circuit 202 in the pinch-off state consumes little power, power consumption can be suppressed. Further, when the oscillation circuit is stopped by the same method, further power saving can be achieved.

  FIG. 5 shows a processing procedure in which the signal processing unit 10 stops the operation of the in-vehicle radar device. That is, the operation of stopping the transmission process of the radar signal from the signal transmission unit. When the stop processing of the own vehicle is detected by the above-described speed detection method of the own vehicle from the normal radar signal transmission processing being on, the signal processing unit 10 determines whether or not the state continues for a certain period of time. . This is intended to detect the stop state accurately by reducing the detection sensitivity so that a false detection state caused by noise or a fine movement state seen in a traffic jam is not determined to be stop. Thereafter, when the relative speed with respect to the ground is zero for a predetermined time, the transmission of the radar signal is stopped by instructing the power supply circuit 13 to change the bias voltage.

  Next, a method for returning the operation of the stopped on-vehicle radar device will be described.

  It is the signal processing unit 10 and the gyro 11 that are involved in this return. The gyro 11 is used for estimating a road shape such as a curve from the force applied to the vehicle in a running state. However, even when the vehicle moves from a stopped state, the output changes. Therefore, in the stop state of the on-vehicle radar device, it is possible to detect that the host vehicle has shifted from the stop state to the travel state by monitoring the integrated value of the output of the gyro 11. This determination is performed by the signal processing unit 10.

  FIG. 6 shows a processing procedure performed by the signal processing unit 10 for returning the operation of the stopped on-vehicle radar device. That is, this is an operation for returning the radar signal transmission processing from the signal transmission unit. When the output of the gyro 11 signal is changed from the radar signal transmission process to the off state, the radar signal transmission process is immediately restored, that is, turned on. This process is realized by instructing the power supply circuit 13 to supply a normal bias to the front end 14.

  In the processing operation described above, a yaw rate sensor can be used instead of the gyro 11. The yaw rate sensor is used for estimating a ground curve state or the like based on a centrifugal force applied to the vehicle depending on the traveling state of the vehicle.

  Note that the in-vehicle radar device described in the first embodiment can detect whether or not the host vehicle is in a stopped state without using information from a vehicle speed sensor coupled to the drive system, and the detection result of the host vehicle can be detected. When stopping, the radar signal transmission process is stopped. When using a vehicle speed sensor, it is necessary to route the harness in order to connect the vehicle speed sensor to the in-vehicle radar system. On the other hand, the on-vehicle radar device described in the first embodiment does not require such harness handling.

  Furthermore, when a vehicle speed sensor is used, the speed detection method differs depending on the type of vehicle, and a signal processing unit for each speed detection method is required. On the other hand, in the on-vehicle radar device described in the first embodiment, since the vehicle speed sensor is not used, the vehicle-mounted radar device can be attached without being limited to the type of vehicle.

  The in-vehicle radar device according to the present invention is used in a system that measures the distance and relative speed with a preceding vehicle and issues an inter-vehicle distance alarm based on the measurement result, or a system that controls the host vehicle to follow the preceding vehicle. Is possible.

It is the figure which showed the structure of the vehicle-mounted radar apparatus by this invention. It is the figure which showed the detailed structure of the front end in FIG. It is the figure which showed the outline | summary of the radar signal in the vehicle which attached the vehicle-mounted radar apparatus. It is a figure which shows the spectrum of the radar signal received by a signal receiving part. It is a figure which shows the process sequence which a signal processing part stops operation | movement of a vehicle-mounted radar apparatus. It is a figure which shows the process sequence which returns operation | movement of the vehicle-mounted radar apparatus which the signal processing part stopped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle-mounted radar apparatus, 10 ... Signal processing part, 11 ... Gyro, 13 ... Power supply circuit, 14 ... Front end, 20 ... Signal transmission part, 21 ... Signal reception part, 201 ... Oscillation circuit, 202 ... Amplification circuit, 203 ... Transmission antenna, 210, 211 ... reception antenna, 212, 213 ... down converter, 214, 215 ... IF signal.

Claims (12)

  An on-vehicle radar device comprising: a signal transmission unit that transmits a radar signal; a signal reception unit that receives a radar signal; and a signal processing unit that processes a radar signal received by the signal reception unit, the signal processing unit Is a vehicle-mounted radar device having a function of detecting the relative speed between the vehicle and the ground from the received radar signal and determining whether or not the vehicle is stopped.   The on-vehicle radar device according to claim 1, wherein the signal processing unit has a function of determining a traveling state of the vehicle based on a signal from a gyroscope or a yaw rate sensor.   The on-vehicle radar device according to claim 1, wherein when it is determined that the vehicle is in a stopped state, transmission of the radar signal of the signal transmission unit is stopped.   The on-vehicle radar device according to claim 1, wherein the vehicle is determined to be stopped after a state in which there is no relative speed between the vehicle and the ground continues for a predetermined time.   The on-vehicle radar device according to claim 1, further comprising an antenna that transmits or receives a radar signal.   6. The on-vehicle radar device according to claim 5, wherein the reception signal processing unit performs signal processing after frequency conversion of the reception signal from the antenna, and calculates a distance, a relative speed, or an angle with the object. In-vehicle radar device.   3. The in-vehicle radar device according to claim 2, wherein when it is determined that the vehicle is in a stopped state, transmission of the radar signal of the signal transmission unit is stopped, and then it is determined that the vehicle is in a traveling state. In the case, the on-vehicle radar device restarts the transmission of the radar signal of the signal transmission unit.   A method for controlling an on-vehicle radar device comprising: a signal transmission unit that transmits a radar signal; a signal reception unit that receives a radar signal; and a signal processing unit that processes a radar signal received by the signal reception unit, The signal processing unit detects a relative speed between the vehicle and the ground from the received radar signal, and determines whether or not the vehicle is in a stopped state.   9. The control method for an on-vehicle radar device according to claim 8, wherein the signal processing unit determines a traveling state of the vehicle based on a signal from a gyroscope or a yaw rate sensor.   The method for controlling an in-vehicle radar device according to claim 8, wherein when the vehicle is determined to be in a stopped state, the transmission of the radar signal of the signal transmission unit is stopped. Control method.   The method for controlling an on-vehicle radar device according to claim 8, wherein the vehicle is determined to be stopped after a state in which there is no relative speed between the vehicle and the ground continues for a predetermined time. Control method. 10. The method for controlling an on-vehicle radar device according to claim 9, wherein when the vehicle is determined to be in a stopped state, transmission of the radar signal of the signal transmission unit is stopped, and then the vehicle is in a traveling state. If it is determined, the control method of the on-vehicle radar device, wherein transmission of the radar signal of the signal transmission unit is resumed.

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