Hyper temporal lidar with dynamic laser control using a laser energy model

Patent metadata

Field	Value
Publication number	US-11442152-B1
Application number	US-202117482787-A
Country	US
Kind code	B1
Filing date	Sep 23, 2021
Priority date	Mar 26, 2021
Publication date	Sep 13, 2022
Grant date	Sep 13, 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 can use a laser energy model to model the available energy in the laser source over time. The timing schedule for laser pulses fired by the lidar system can then be determined using energies that are predicted for the different scheduled laser pulse shots based on the laser energy model. This permits the lidar system to reliably ensure at a highly granular level that each laser pulse shot has sufficient energy to meet operational needs, including when operating during periods of high density/high resolution laser pulse firing. The laser energy model is capable of modeling the energy available for laser pulses in the laser source over very short time intervals (such as 10-100 nanoseconds).

First claim

What is claimed is:

1. A lidar apparatus comprising:
a laser source;
a mirror subsystem that defines where the lidar apparatus is aimed within a field of view, wherein the mirror subsystem is optically downstream from the laser source; and
a control circuit that dynamically schedules a variable rate firing of laser pulse shots by the laser source using a laser energy model as compared to a plurality of energy requirements relating to the laser pulse shots, wherein the laser pulse shots are transmitted from the laser source into the field of view via the mirror subsystem in accordance with the scheduled variable rate firing; and
wherein the laser energy model predictively (1) models a depletion of energy in the laser source in response to each scheduled laser pulse shot, (2) models a retention of energy in the laser source after scheduled laser pulse shots, and (3) models a buildup of energy in the laser source between scheduled laser pulse shots to support the dynamic scheduling of laser pulse shots in view of their energy requirements.

2. The apparatus of claim 1 wherein the laser source comprises an optical amplification laser source.

3. The apparatus of claim 2 wherein the optical amplification laser source comprises a pulsed fiber laser source.

4. The apparatus of claim 3 wherein the pulsed fiber laser source comprises a seed laser, a pump laser, and a fiber amplifier, and wherein the laser energy model models (1) seed energy for the pulsed fiber laser source over time and (2) energy stored in the fiber amplifier over time.

5. The apparatus of claim 2 wherein the laser energy model (1) models depletion of energy in an optical amplifier of the optical amplification laser source in response to each scheduled laser pulse shot, (2) models retention of energy in the optical amplifier after scheduled laser pulse shots, and (3) models buildup of energy in the optical amplifier between scheduled laser pulse shots.

6. The apparatus of claim 1 wherein the laser energy model models available laser energy for laser pulse shots at time intervals in a range between 10 nanoseconds to 100 nanoseconds.

7. The apparatus of claim 1 wherein the energy requirements include a minimum laser pulse energy.

8. The apparatus of claim 7 , wherein the minimum laser pulse energy is non-uniform for the laser pulse shots.

9. The apparatus of claim 1 wherein the energy requirements include a maximum energy threshold relating to the laser source.

10. The apparatus of claim 1 wherein the control circuit determines energy amounts to include in the laser pulse shots that target range points based on estimates of ranges for detected objects in the field of view corresponding to the range points.

11. The apparatus of claim 1 wherein the control circuit updates the laser energy model based on feedback data indicative of actual energy amounts in the fired laser pulse shots.

12. The apparatus of claim 1 wherein the control circuit uses lookup tables based on the laser energy model to simulate energy characteristics for different time sequences of laser pulse shots.

13. The apparatus of claim 1 wherein the mirror subsystem comprises a first mirror and a second mirror, and wherein the control circuit controls a scanning of the first and second mirrors to define where the lidar apparatus is aimed within the field view.

14. The apparatus of claim 13 wherein the control circuit (1) drives the first mirror to scan in a resonant mode and (2) drives the second mirror to scan in a point-to-point mode based on a plurality of range points to be targeted with the scheduled laser pulse shots.

15. The apparatus of claim 1 wherein the control circuit (1) dynamically schedules the variable rate firing of laser pulse shots by translating a plurality of range points in the field of view that are to be targeted with laser pulse shots into a shot list using the laser energy model as compared to the energy requirements and (2) provides firing commands to the laser source based on the shot list, wherein the shot list defines a timed sequence of the range points to be targeted with the scheduled laser pulse shots.

16. The apparatus of claim 15 wherein the laser energy model quantitatively predicts available laser energy amounts for laser pulse shots based on a history of prior laser pulse shots.

17. 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 using the laser energy model as compared to the energy requirements and (2) provides the shot list to the beam scanner controller, wherein the shot list defines a timed sequence of range points in the field of view to be targeted with the scheduled laser pulse shots; and
wherein the beam scanner controller (1) provides firing commands to the laser source based on the provided shot list and (2) dynamically controls a scanning of a mirror within the mirror subsystem based on the shot list.

18. A lidar apparatus comprising:
a first mirror that is scannable to define where the lidar apparatus is aimed along a first axis in a field of view;
a second mirror that is scannable to define where the lidar apparatus is aimed along a second axis in the 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;
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) determines, based on the laser energy model and energy levels for a plurality of laser pulses to be transmitted, a timing schedule that schedules the laser pulses for transmission, and (4) 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 via the first and second mirrors; and
wherein the maintained laser energy model predictively (1) models a depletion of energy in the laser source in response to each scheduled laser pulse, (2) models a retention of energy in the laser source after scheduled laser pulses, and (3) models a buildup of energy in the laser source between scheduled laser pulses to support the determination of the timing schedule in view of the energy levels for the laser pulses to be transmitted.

19. The apparatus of claim 18 wherein the energy levels are defined for laser pulses which are to target a plurality of range points in the field of view.

20. The apparatus of claim 18 wherein the laser source comprises a seed laser, a pump laser, and an optical amplifier;
wherein the laser energy model models (1) seed energy for the laser source and (2) stored energy in the optical amplifier; and
wherein the control circuit updates the laser energy model over time as laser pulses are transmitted by the apparatus.

21. The apparatus of claim 20 wherein the optical amplifier comprises a fiber amplifier, wherein the laser energy model models the available energy for laser pulses according to a relationship of EF(t+δ)=aS(t+δ)+bEF(t), wherein a+b=1 so that a and b reflect how much energy is drained from and remains in the fiber amplifier when laser pulses are fired, wherein EF(t) represents laser

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

• G01S17/10

  using transmission of interrupted, pulse-modulated waves (determination of distance by phase measurements G01S17/32) · CPC title

• G01S7/484 Primary

  Transmitters · CPC title