Techniques for detecting and mitigating interference among multiple LiDAR sensors
A LiDAR system includes a LiDAR sensor and an infrared (IR) camera. The LiDAR sensor includes one or more light sources configured to emit a set of light pulses, one or more detectors configured to receive a set of return light pulses, and a processor configured to determine a time of flight for each return light pulse, and obtain a point cloud based on the times of flight of the set of return light pulses. The IR camera is configured to capture IR images concurrently with operation of the LiDAR sensor, analyze the IR images to detect presence of suspicious IR pulses, and provide information about the suspicious IR pulses to the LiDAR sensor. The processor of the LiDAR sensor is further configured to identify one or more points of the point cloud as suspicious points due to interference based on the information about the suspicious IR pulses.
1 . A method of operating a LiDAR system, the method comprising:
emitting, using an array of light sources, a train of light pulses directed toward a scene within a field of view of the LiDAR system;
detecting, using an array of detectors, a return light pulse during a first time window, wherein the array of detectors is arranged to have a detection time window and an idle time window between pulses of the train of light pulses, and the first time window is during the detection time window;
determining a time of flight for the return light pulse, thereby obtaining a first point of a point cloud;
detecting, using the array of detectors and in a second time window, a second light pulse wherein the second time window is during the idle time window of the array of detectors, so that a LiDAR sensor of the LiDAR system can detect interfering laser pulses using a detector that would otherwise be idle at a given time;
labeling a signal of the second light pulse as a suspicious signal due to interference based on the second light pulse being detected during the idle time window of the LiDAR sensor;
determining timings of suspicious signals, using data from the array of detectors during idle time windows; and
controlling the array of light sources to emit the train of light pulses so that the train of light pulses is temporally synchronized with the suspicious signals, thereby mitigating interference.
2 . The method of claim 1 further comprising discarding the signal of the second light pulse.
3 . The method of claim 1 further comprising:
detecting, using the array of detectors and in one or more detection time windows subsequent to the first time window, one or more third light pulses; and
labeling the one or more third light pulses as suspicious signals due to interference.
4 . The method of claim 1 further comprising:
detecting a third pulse, using the array of detectors, in a third time window; and
labeling the third pulse as a suspicious signal due to interference.
5 . The method of claim 1 further comprising:
comparing an intensity of a detected light pulse corresponding to the second light pulse with an expected intensity range; and
upon determining that the intensity of the second light pulse is outside the expected intensity range, discarding the signal of the second light pulse.
6 . The method of claim 1 further comprising:
comparing a pulse width of a detected light pulse with a nominal pulse width of a pulse in the train of light pulses; and
upon determining that the pulse width of the detected light pulse differs from the nominal pulse width by a threshold amount, discarding the signal of the detected light pulse.
7 . The method of claim 1 further comprising:
estimating a distance to a second lidar sensor, and
labeling distances in a direction of the second lidar sensor as suspicious that have a difference from the distance estimated that are above a threshold.
8 . The method of claim 1 further comprising:
determining timings of suspicious signals; and
blocking a pixel in a time window based on determining timings of the suspicious signals.
9 . The method of claim 1 further comprising using vehicle-to-vehicle communication to synchronize multiple LiDAR sensors.
10 . The method of claim 1 further comprising using a precision timing signal from a Global Navigation Satellite System to synchronize multiple LiDAR sensors.
11 . The method of claim 1 further comprising:
determining timings of suspicious signals, using data from the array of detectors during idle time windows; and
controlling the array of light sources, based on determining timings of the suspicious signals, to emit the train of light pulses so that the train of light pulses is temporally controlled to mitigate interference with the suspicious signals.