Hyper Temporal Lidar with Controllable Detection Intervals Based on Environmental Conditions
A lidar receiver that includes a photodetector circuit can be controlled so that the detection intervals used by the lidar receiver to detect returns from fired laser pulse shots are closely controlled. Such control over the detection intervals used by the lidar receiver allows for close coordination between a lidar transmitter and the lidar receiver where the lidar receiver is able to adapt to variable shot intervals of the lidar transmitter (including periods of high rate firing as well as periods of low rate firing). The lidar receiver can use data indicative of environmental conditions for the lidar receiver's field of view to define the detection intervals.
1 . A lidar system comprising:
a photodetector circuit, the photodetector circuit comprising an array of pixels for sensing incident light; and
a control circuit;
wherein the control circuit (1) processes a shot list, the shot list comprising data that defines a plurality of laser pulse shots that target a plurality of range points in a field of view and (2) determines a plurality of detection intervals associated with the laser pulse shots based on the processed shot list and defined criteria, the detection intervals for detecting returns from their associated laser pulse shots, and wherein the defined criteria comprises data indicative of environmental conditions; and
wherein the photodetector circuit selectively starts and stops collections from a plurality of pixels of the array in accordance with the determined detection intervals to control the photodetector circuit to sense the returns from the laser pulse shots.
2 . The system of claim 1 wherein the environmental conditions include daytime ambient lighting conditions.
3 . The system of claim 1 wherein the environmental conditions include nighttime ambient and artificial lighting conditions.
4 . The system of claim 1 wherein the environmental conditions include weather conditions.
5 . The system of claim 1 wherein the environmental conditions include city environment conditions.
6 . The system of claim 1 wherein the control circuit, for each of a plurality of the laser pulse shots, identifies a pixel set of the array to use for sensing a return from that laser pulse shot, and wherein the determined detection intervals are associated with corresponding identified pixel sets; and
wherein the photodetector circuit starts and stops collections from the identified pixel sets in accordance with their associated corresponding determined detection intervals.
7 . The system of claim 6 wherein the control circuit identifies the pixel sets based on the range points that are targeted by the laser pulse shots.
8 . The system of claim 7 wherein the shot list identifies the targeted range points for the laser pulse shots by azimuth and elevation angles.
9 . The system of claim 6 wherein each of the identified pixel sets comprises one or more of the pixels of the array.
10 . The system of claim 6 wherein each of a plurality of the determined detection intervals comprises (1) first data that indicates when to start collection from its corresponding identified pixel set and (2) second data that indicates when to stop collection its corresponding identified pixel set.
11 . The system of claim 10 wherein, for each of a plurality of the determined detection intervals, the first and second data comprise start and stop collection times for the identified pixel set associated with that determined detection interval.
12 . The system of claim 1 wherein the determined detection intervals are non-overlapping.
13 . The system of claim 1 wherein the defined criteria further comprise data indicative of a settle time for the pixels.
14 . The system of claim 1 wherein the control circuit activates pixels of the array to be used for detecting the returns sufficiently prior to when collections are to start from the activated pixels for a pixel settle time to have passed when the collections are to start from the activated pixels.
15 . The system of claim 1 wherein the defined criteria further comprise data indicative of scheduled fire times for next laser pulse shots from the shot list.
16 . The system of any of claim 1 further comprising:
a signal processing circuit that processes sensed signal data from the photodetector circuit to (1) detect the returns within the sensed signal data and (2) compute return data for the detected returns.
17 . The system of claim 16 wherein the signal processing circuit comprises a plurality of processors that share processing of the sensed signal data.
18 . The system claim 1 further comprising:
a lidar transmitter, wherein the lidar transmitter comprises a scannable mirror, and wherein the lidar transmitter transmits the laser pulse shots toward the targeted range points via the scannable mirror.
19 . The system of claim 18 wherein the lidar transmitter scans the scannable mirror in a resonant mode.
20 . The system of claim 19 wherein the lidar transmitter scans the scannable mirror in the resonant mode at a scan frequency in a range between 100 Hz and 20 kHz.
21 . The system of claim 19 wherein the lidar transmitter scans the scannable mirror in the resonant mode at a scan frequency in a range between 10 kHz and 15 kHz.
22 . The system of claim 18 wherein the scannable mirror comprises a first scannable mirror and a second scannable mirror, wherein the lidar transmitter transmits the laser pulse shots toward the targeted range points via the first and second scannable mirrors.
23 . The system of claim 22 wherein the lidar transmitter scans the second scannable mirror in a point-to-point mode according to a step function that varies as a function of the range points targeted with the laser pulse shots.
24 . The system of claim 22 wherein the second scannable mirror is optically downstream from the first scannable mirror.
25 . The system of claim 18 wherein the lidar transmitter and the photodetector circuit are in a bistatic arrangement with respect to each other.
26 . The system of claim 18 further comprising a laser source that generates the laser pulse shots, and wherein the control circuit schedules the laser pulse shots in the shot list according to a laser energy model for the laser source.
27 . The system of claim 26 wherein the control circuit schedules the laser pulse shots in the shot list according to the laser energy model and a mirror motion model for the scannable mirror.
28 . The system of claim 1 wherein the array comprises a two-dimensional (2D) array of pixels.
29 . A method for controlling a lidar receiver, wherein the lidar receiver comprises a photodetector, the photodetector comprising an array of pixels, the method comprising:
processing a shot list, the shot list comprising data that defines a plurality of laser pulse shots that target a plurality of range points in a field of view;
determining a plurality of detection intervals associated with the laser pulse shots based on the processed shot list and defined criteria, the detection intervals for detecting returns from their associated laser pulse shots, and wherein the defined criteria comprises data indicative of environmental conditions;
selectively starting and stopping collections from pixels of the array in accordance with the determined detection intervals to control the photodetector to detect the returns from the laser pulse shots.
30 . An article of manufacture for controlling a lidar receiver, wherein the lidar receiver comprises a photodetector, the photodetector comprising an array of pixels, the article of manufacture comprising:
machine-readable code that is resident on a non-transitory machine-readable storage medium, wherein the code defines processing operations to be performed by a processor to cause the processor to:
process a shot list, the shot list comprising data that defines a plurality of laser pulse shots that target a plurality of range points in a field of view;
determine a plurality of detection intervals associated with the laser pulse shots based on the processed shot list and defined criteria, the detection intervals for detecting returns from their associated laser pulse shots, and wherein the defined criteria comprises data indicative of environmental conditions;
selectively start and stop collections from pixels of the array in accordance with the determined detection intervals to control the photodetector to detect the returns from the laser pulse shots.