Hyper temporal LIDAR with dynamic laser control using laser energy and mirror motion models

Patent metadata

Field	Value
Publication number	US-11448734-B1
Application number	US-202117482793-A
Country	US
Kind code	B1
Filing date	Sep 23, 2021
Priority date	Mar 26, 2021
Publication date	Sep 20, 2022
Grant date	Sep 20, 2022

Abstract

A lidar system that includes a laser source and transmits laser pulses produced by the laser source toward range points in a field of view via a mirror that scans through a plurality of scan angles can use (1) a laser energy model to model the available energy in the laser source over time and (2) a mirror motion model to model motion of the mirror over time. Time slots for transmitting the targeted laser pulses can be identified using the mirror motion model, and a schedule for these pulses can be determined using energies predicted for the pulses at these time slots according to the laser energy model. Linking the model of mirror motion with the model of laser energy provides highly precise granularity when scheduling laser pulses targeted at specific range points in the field of view.

First claim

What is claimed is:

1. A lidar apparatus comprising:
a laser source;
a mirror subsystem comprising a mirror that is scannable through a plurality of scan angles to define where the lidar apparatus is aimed within a field of view, and wherein the mirror subsystem is optically downstream from the laser source; and
a control circuit that dynamically controls a variable rate firing of laser pulse shots by the laser source toward a plurality of range points in the field of view, wherein the control circuit dynamically controls the variable rate firing using (1) a laser energy model that models how much energy is available from the laser source for laser pulse shots over time as compared to a plurality of energy requirements relating to the targeted laser pulse shots and (2) a mirror motion model that models the scan angles for the scannable mirror over time as a plurality of corresponding time slots, wherein the fired laser pulse shots are transmitted from the laser source into the field of view toward the range points via the scannable mirror; and
wherein the control circuit schedules the targeted laser pulse shots into time slots based on the laser energy model by evaluating different assignments of the targeted laser pulse shots into time slots according to the mirror motion model to identify (i) which of the assignments complies with the energy requirements for the targeted laser pulse shots according to the laser energy model and (ii) which of one or more compliant assignments exhibits a shortest completion time according to the mirror motion model, wherein the compliant assignment that exhibits the shortest completion time defines a sequence for the scheduled targeted laser pulse shots.

2. The apparatus of claim 1 wherein the control circuit processes a group of scan angles to be targeted with laser pulse shots to schedule the targeted laser pulse shots by (1) identifying time slots corresponding to the scan angles of the group according to the mirror motion model and (2) identifying different sequences of the identified time slots that serve as the different assignments of the targeted laser pulse shots into time slots that are to be evaluated according to the laser energy model.

3. The apparatus of claim 1 wherein the control circuit controls the variable rate firing of the targeted laser pulse shots by the laser source in accordance with the defined sequence.

4. The apparatus of claim 1 wherein the time slots reflect time intervals in a range between 5 nanoseconds and 50 nanoseconds.

5. The apparatus of claim 1 wherein the mirror motion model models the scan angles according to a cosine oscillation.

6. The apparatus of claim 1 wherein the control circuit drives the scannable mirror to scan in a resonant mode.

7. The apparatus of claim 6 wherein the scannable mirror comprises a first scannable mirror that is scannable along a first axis, wherein the mirror subsystem further comprises a second scannable mirror that is scannable along a second axis orthogonal to the first axis, and wherein the first and second scannable mirrors define where the lidar apparatus is aimed within the field of view.

8. The apparatus of claim 7 wherein the control circuit drives the second scannable mirror to scan in a point-to-point mode based on the range points to be targeted with the fired laser pulse shots.

9. The apparatus of claim 6 wherein the control circuit controls the scannable mirror to scan at a frequency in a range between 10 kHz and 15 kHz.

10. The apparatus of claim 1 wherein the control circuit updates the mirror motion model based on feedback data indicative of actual scan positions for the scannable mirror.

11. The apparatus of claim 1 wherein the control circuit comprises (1) a system controller and (2) a beam scanner controller;
wherein the system controller (1) generates a shot list from a group of range points that are to be targeted with laser pulse shots based on the scheduling and (2) provides the shot list to the beam scanner controller, wherein the shot list defines a schedule for laser pulse shots including the defined sequence; and
wherein the beam scanner controller provides firing commands to the laser source based on the provided shot list.

12. The apparatus of claim 1 wherein the time slots reflect intervals in a range between 5 nanoseconds and 50 nanoseconds.

13. The apparatus of claim 1 wherein the energy requirements include energy requirements that vary across different laser pulse shots.

14. The apparatus of claim 1 wherein the laser energy model quantitatively predicts available energy amounts from the laser source for laser pulse shots over time based on a history of prior laser pulse shots.

15. The apparatus of claim 14 wherein the laser energy model models a retention of energy in the laser source after laser pulse shots.

16. A lidar apparatus comprising:
a first mirror that is scannable to a plurality of first mirror scan angles;
a second mirror that is scannable to a plurality of second mirror scan angles, wherein the scan angles for the first and second mirrors define, in combination, a plurality of range points to which the lidar apparatus is aimed in a field of view;
a control circuit; and
a laser source that is optically upstream from the first and second mirrors;
wherein the laser source generates laser pulses for transmission into the field of view via the first and second mirrors in response to firing commands from the control circuit; and
wherein the control circuit (1) controls scanning of the first and second mirrors, (2) maintains a laser energy model that dynamically models available energy for laser pulses from the laser source over time, (3) maintains a mirror motion model that models the first mirror scan angles over time as a plurality of corresponding time slots, (4) determines available energy from the laser source for laser pulses at a plurality of the time slots based on the laser energy model, (5) determines, based on the laser energy model and the mirror motion model, a timing schedule for laser pulses to be transmitted toward a plurality of targeted range points in the field of view, wherein the targeted range points have corresponding first mirror scan angles, and (6) provides firing commands to the laser source based on the determined timing schedule to trigger generation of the laser pulses for transmission from the laser source into the field of view toward the targeted range points via the first and second mirrors; and
wherein the control circuit determines the timing schedule by (1) identifying time slots that, according to the mirror motion model, correspond to the first mirror scan angles of the targeted range points with respect to a plurality of different shot order candidates, (2) evaluating a plurality of different shot order candidates for the timing schedule based on comparisons of a plurality of energy requirements for laser pulses with the determined available energies to be fired at the identified time slots for the different shot order candidates, and (3) selecting the shot order candidate for the timing schedule based on (i) which of the shot order candidates is compliant with the energy requirements according to the laser energy model and (ii) which of one or more compliant shot order candidates exhibits a shortest completion time according to the mirror motion model.

17. The apparatus of claim 16 wherein the time slots include time slots for a scan of the first mirror in a first scan direction and a return scan of the first mirror in a second scan direction.

18. The apparatus

Assignees

• Aeye Inc

Inventors

• Feru Philippe
• Dussan Luis
• Benscoter Joel
• Liang Alex
• Polishchuk Igor
• Steinhardt Allan

Classifications

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G01S7/4816

  of receivers alone · CPC title

• G01S7/4817 Primary

  relating to scanning · CPC title

• G01S17/89

  for mapping or imaging · CPC title

• G01S17/931

  of land vehicles · CPC title