Hyper Temporal Lidar with Shot-Specific Detection Control
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).
1 . A lidar system comprising:
a lidar receiver, wherein the lidar receiver comprises a photodetector, the photodetector comprising an array of pixels; and
a control circuit for controlling the lidar receiver;
wherein the control circuit determines data indicative of a detection interval for detecting a return from a laser pulse shot based on a plurality of defined criteria;
wherein the control circuit generates and provides control data to the lidar receiver for controlling how the lidar receiver detects the return, wherein the control data comprises (1) first data that identifies a pixel set of the array to use for detecting the return, (2) second data for controlling when to start collection from the identified pixel set for detecting the return, and (3) third data for controlling when to stop collection from the identified pixel set, wherein the second data and the third data are based on the determined detection interval data and define a time period for detecting the return;
wherein the lidar receiver, in response to the provided control data, (1) selects the pixel set identified by the first data for readout to support detecting the return at a start of the defined time period in accordance with the second data and (2) stops readout from the identified pixel set at a conclusion of the defined time period in accordance with the third data; and
wherein the control circuit and lidar receiver perform their respective operations for a plurality of returns from a plurality of laser pulse shots.
2 . The system of claim 1 wherein the determined detection interval data comprises a minimum range for an object in a field of view to be targeted with the laser pulse shot.
3 . The system of claim 1 wherein the determined detection interval data comprises a maximum range for an object in a field of view to be targeted with the laser pulse shot.
4 . The system of claim 1 wherein the determined detection interval data comprises (1) a minimum range for an object in a field of view to be targeted with the laser pulse shot and (2) a maximum range for the object, and wherein the control circuit translates the minimum and maximum ranges into the first and second data.
5 . The system of claim 1 wherein each of the identified pixel sets comprises one or more of the pixels of the array.
6 . The system of claim 1 wherein the control circuit identifies the pixel sets for the first data with respect to the laser pulse shots based on a plurality of range points in a field of view that are targeted by the laser pulse shots.
7 . The system of claim 6 wherein the range points targeted by the laser pulse shots are identified by azimuth and elevation angles.
8 . The system of claim 6 wherein the identified pixel sets follow a pattern that correspond to the range points targeted by the laser pulse shots.
9 . The system of claim 1 wherein the time periods defined by the detection interval data for the laser pulse shots are non-overlapping.
10 . The system of claim 1 wherein the control circuit (1) defines activation times for the identified pixel sets based on a settle time for the pixels and (2) activates the identified pixel sets based on the defined activation times to enable collections to start from the identified pixel sets in accordance with the second data.
11 . The system of any of claim 1 further comprising:
a signal processing circuit that processes sensed signal data from the identified pixel sets to (1) detect the returns within the sensed signal data and (2) compute return data for the detected returns.
12 . The system of claim 11 wherein the signal processing circuit comprises a plurality of processors that share processing of the sensed signal data.
13 . The system of claim 11 wherein the signal processing circuit updates a lidar point cloud with the computed return data.
14 . 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 a plurality of targeted range points in a field of view via the scannable mirror.
15 . The system of claim 14 wherein the lidar transmitter scans the scannable mirror in a resonant mode.
16 . The system of claim 15 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.
17 . The system of claim 15 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.
18 . The system of claim 14 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.
19 . The system of claim 18 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.
20 . The system of claim 18 wherein the second scannable mirror is optically downstream from the first scannable mirror.
21 . The system of claim 14 wherein the lidar transmitter and the photodetector are in a bistatic arrangement with respect to each other.
22 . The system of claim 14 further comprising a laser source that generates the laser pulse shots, and wherein the control circuit schedules the laser pulse shots according to a laser energy model for the laser source.
23 . The system of claim 22 wherein the control circuit schedules the laser pulse shots according to the laser energy model and a mirror motion model for the scannable mirror.
24 . The system of claim 1 wherein the array comprises a two-dimensional (2D) array of pixels.
25 . A method for controlling a lidar receiver, wherein the lidar receiver comprises a photodetector, the photodetector comprising an array of pixels, the method comprising:
determining data indicative of a detection interval for a return from a laser pulse shot based on a plurality of defined criteria;
generating control data for controlling how the lidar receiver detects the return, wherein the control data comprises (1) first data that identifies a pixel set of the array to use for detecting the return, (2) second data that identifies when to start collection from the identified pixel set for detecting the return, and (3) third data that identifies when to stop collection from the identified pixel set with respect to detecting the return, wherein the second data and the third data are based on the determined detection interval data and define a time period for detecting the return;
providing the control data to the lidar receiver to (1) select the pixel set identified by the first data for readout to support detecting the return at a start of the defined time period in accordance with the second data and (2) stop readout from the identified pixel set at a conclusion of the defined time period in accordance with the third data; and
performing the determining, generating, and providing steps for a plurality of returns from a plurality of laser pulse shots.
26 . The method of claim 25 wherein the determined detection interval data comprises a minimum range for an object in a field of view to be targeted with the laser pulse shot.
27 . The method of claim 25 wherein the determined detection interval data comprises a maximum range for an object in a field of view to be targeted with the laser pulse shot.
28 . 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 range values associated with the laser pulse shots based on the processed shot list and defined criteria, wherein the determined detection range values for use in controlling a lidar receiver with respect to ranges by which the lidar receiver will detect returns from the laser pulse shots.
29 . The article of manufacture of claim 28 wherein the code further defines processing operations that cause the processor to:
access a lidar point cloud to determine range estimates for a plurality of shot coordinates from the shot list; and
assign detection range values for the laser pulse shots that target the shot coordinates from the lidar point cloud based on the determined range estimates.