# US 8,788,115 B2 · Detecting an abnormal driving condition

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- Number: US 8,788,115 B2
- Document ID: US8788115B2
- Status: Granted
- Kind: B2
- Application number: 13/969,021
- Filed: 2013-08-16
- Published: 2014-02-06
- Granted: 2014-07-22
- Earliest claimed: 2012-07-31
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Xin Hao Cheng; Guoqiang Hu; Li Jun Mei; Bo Yang; Yu Yuan
- Web page: https://patentgrep.com/patent/US8788115B2

## CPC

- G08G 1/162: {event-triggered}
- G01S 11/10: using Doppler effect
- G08G 1/052: with provision for determining speed or overspeed {(speed measuring in general G01P)}
- G08G 1/163: {involving continuous checking}
- G08G 1/166: {for active traffic, e.g. moving vehicles, pedestrians, bikes}
- G08G: TRAFFIC CONTROL SYSTEMS (guiding railway traffic, ensuring the safety of railway traffic B61L; arrangement of road signs or traffic signals E01F9/00; radar or analogous systems, sonar systems, lidar systems specially adapted for traffic control G01S13/91, G01S15/88, G01S17/88; {radar or analogous systems, sonar systems, lidar systems specially adapted for anti-collision purposes G01S13/93, G01S15/93, G01S17/93})
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A method of detecting an abnormal driving includes receiving a RF signal transmitted from a vehicle in front; performing digital down conversion on the RF signal to obtain a baseband digital signal; performing frequency shift detection on the baseband digital signal to obtain frequency shift between the received RF signal and the RF signal transmitted from the vehicle in front; and determining that the abnormal driving condition in front exists response to determining that the frequency shift has reached a set threshold.

## Claims

### Claim 1

An apparatus for detecting an abnormal driving condition, the apparatus comprising:
a receiving module configured to receive, by a first vehicle, an RF signal transmitted from a second vehicle located in front of the first vehicle;
a digital down conversion module configured to perform digital down conversion on the RF signal to obtain a baseband digital signal;
a frequency shift detection module configured to perform frequency shift detection on the baseband digital signal to obtain a frequency shift between the received RF signal and the RF signal transmitted from the second vehicle;
a frequency comparison module configured to determine whether the frequency shift reaches a set threshold; and
a determining module configured to determine the abnormal driving condition of the second vehicle exists responsive to determining that the frequency shift has reached the set threshold.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein the frequency shift detection module comprises:
a sample point obtaining module configured to obtain adjacent first sample point and second sample point of the baseband digital signal;
a complex vector representing module configured to represent the first sample point as a first complex vector and to represent the second sample point as a second complex vector;
a phase difference computing module configured to compute phase difference between the first complex vector and the second complex vector;
a frequency shift computing module configured to compute frequency shift between the received RF signal and the RF signal transmitted from the vehicle in front based on the phase difference.

### Claim 3 (depends on 1)

The apparatus according to claim 1, wherein the frequency shift detection module comprises:
a sample point obtaining module configured to obtain a plurality of continuous sample points of the baseband digital signal;
a complex vector representing module configured to represent the plurality of continuous sample points as complex vectors;
a phase difference computing module configured to compute phase differences between complex vectors corresponding to adjacent sample points in the plurality of continuous sample points;
an average phase difference obtaining module configured to perform weighted averaging on the phase differences to obtain average phase difference;
a frequency shift computing module configured to compute frequency shift between the received RF signal and the RF signal transmitted from the second vehicle based on the average phase difference.

### Claim 4 (depends on 1)

The apparatus according to claim 1, wherein the frequency shift detection module comprises:
a sample point obtaining module configured to obtain sample points of the baseband digital signal;
a time frequency transformation module configured to perform time frequency transformation on the sample points of the baseband digital signal to obtain a set of amplitudes corresponding to a set of frequency points;
an amplitude comparison module configured to compare the amplitudes with a preset valid amplitude;
a frequency point filtering module configured to filter out frequency points corresponding to amplitudes which are greater than the valid amplitude;
a frequency difference computing module configured to compute frequency differences for each of the filtered-out frequency points between the filtered-out frequency points and a reference modulation frequency of the baseband digital signal, and to select a largest frequency difference as the frequency shift.

### Claim 5 (depends on 1)

The apparatus according to claim 1, further comprising: a low pass filtering module configured to perform low pass filtering on the baseband digital signal before performing frequency shift detection on the baseband digital signal.

### Claim 6 (depends on 5)

The apparatus according to claim 5, further comprising: a transmitting module configured to transmit another RF signal to a third vehicle at behind the first vehicle via a directional antenna.