CN-116075741-B - Dynamic laser power control for LiDAR systems

CN116075741BCN 116075741 BCN116075741 BCN 116075741BCN-116075741-B

Abstract

Embodiments of the present invention provide an optical sensing system, a method of controlling a transmit power level in an optical sensing system, and a control apparatus for controlling a transmit power level in an optical sensing system. An exemplary optical sensing system includes an emitter configured to emit a light beam from a plurality of perpendicular detection angles to scan an object. The optical sensing system further includes a controller configured to dynamically vary the emitted power level of the light beam emitted at each vertical detection angle. The optical sensing system further includes a receiver configured to detect the light beam returned by the object.

Inventors

Ye Youjing
Lv yue

Assignees

北京航迹科技有限公司

Dates

Publication Date: 20260508
Application Date: 20210608
Priority Date: 20200703

Claims (15)

1. An optical sensing system, comprising: an emitter configured to emit light beams from a plurality of vertical detection angles to scan an object; a controller configured to dynamically vary the emitted power level of the light beam emitted at each of the vertical detection angles, comprising: Determining detection distances of light beams corresponding to the vertical detection angles, wherein when the vertical detection angle is smaller than a threshold angle, the threshold detection distance of the optical sensing system is determined as the detection distance corresponding to the vertical detection angle, when the vertical detection angle is larger than the threshold angle, the detection distance is determined based on the vertical detection angle and the height of the optical sensing system from the ground plane, and Determining the transmission power level based on the ratio of the detection distance corresponding to the vertical detection angle to the threshold detection distance for each vertical detection angle, and A receiver configured to detect a beam returned by the object.
2. The optical sensing system of claim 1, wherein the optical sensing system comprises a light detection and ranging system.
3. The optical sensing system of claim 1, wherein the emitter further comprises an emitter configured to emit a light beam and a drive circuit configured to drive the emitter to emit a light beam at a dynamically varying emitted power level.
4. The optical sensing system of claim 3, wherein the controller is configured to provide at least one control signal to the drive circuit, the drive circuit configured to provide a varying drive current to the emitter in response to the at least one control signal, wherein the varying drive current is proportional to the dynamically varying emitted power level.
5. The optical sensing system of claim 4, wherein the at least one control signal is used to vary at least one of an amplitude or a pulse width of the drive current.
6. An optical sensing system according to claim 3, wherein the drive circuit comprises a FET control drive circuit or a capacitive discharge drive circuit.
7. The optical sensing system of claim 1, wherein to dynamically change the emitted power level of the light beam, the controller is further configured to: And when the vertical detection angle is larger than the threshold angle, reducing the transmission power level.
8. The optical sensing system of claim 1, wherein the transmit power level is proportional to the square of the ratio of the detection distance and the threshold detection distance.
9. The optical sensing system of claim 1, wherein the controller is further configured to determine a first reflectivity of the object based on the light beam received by the receiver, wherein the transmit power level is proportional to a ratio of a second reflectivity of the ground to the first reflectivity.
10. A method for controlling a transmit power level in an optical sensing system, comprising: transmitting a light beam at a plurality of vertical detection angles by an transmitter to scan an object; Dynamically changing, by a controller, the emitted power level of the light beam at each of the vertical detection angles, comprising: Determining detection distances of light beams corresponding to the vertical detection angles, wherein when the vertical detection angle is smaller than a threshold angle, the threshold detection distance of the optical sensing system is determined as the detection distance corresponding to the vertical detection angle, when the vertical detection angle is larger than the threshold angle, the detection distance is determined based on the vertical detection angle and the height of the optical sensing system from the ground plane, and Determining the transmission power level based on the ratio of the detection distance corresponding to the vertical detection angle to the threshold detection distance for each vertical detection angle, and The beam returned by the object is detected by a receiver.
11. The method of claim 10, further comprising: the transmit power level is reduced when the vertical detection angle is greater than the threshold angle.
12. The method of claim 10, wherein the step of determining the position of the first electrode is performed, The emitter further includes an emitter configured to emit the light beam and a driving circuit configured to drive the emitter; The method further includes providing at least one control signal to the drive circuit to cause the drive circuit to provide a varying drive current to the emitter in response to the at least one control signal, wherein the varying drive current is proportional to a dynamically varying transmit power level.
13. The method of claim 10, wherein the transmit power level is proportional to the square of the ratio of the detected distance and the threshold detected distance.
14. A control device for controlling a transmit power level in an optical sensing system, comprising: A driving circuit configured to drive an emitter of the optical sensing system to emit a light beam, wherein the light beam is emitted at a plurality of vertical detection angles, and A controller configured to control the driving circuit to dynamically change a transmission power level of the light beam transmitted at each of the vertical detection angles, comprising: Determining detection distances of light beams corresponding to the vertical detection angles, wherein when the vertical detection angle is smaller than a threshold angle, the threshold detection distance of the optical sensing system is determined as the detection distance corresponding to the vertical detection angle, when the vertical detection angle is larger than the threshold angle, the detection distance is determined based on the vertical detection angle and the height of the optical sensing system from the ground plane, and For each vertical detection angle, determining the transmission power level based on a ratio of the detection distance corresponding to the vertical detection angle to the threshold detection distance.
15. The control device of claim 14, wherein the controller is further configured to provide at least one control signal to the drive circuit, and the drive circuit is configured to provide a varying drive current to the emitter in response to a voltage command signal, wherein the varying drive current is proportional to the dynamically varying transmit power level.

Description

Dynamic laser power control for LiDAR systems Cross reference The present application claims priority from U.S. patent application Ser. No. 16/920,650, filed 7/3/2020, which is expressly incorporated herein by reference in its entirety. Technical Field The present disclosure relates to laser power control for light detection and ranging (LiDAR) systems, and more particularly, to dynamic laser power control to compensate for variations in detection distance at different vertical detection angles of the LiDAR system. Background Optical sensing systems, such as LiDAR systems, have been widely used in advanced navigation technologies, such as assisting in autopilot or generating high definition maps. For example, one typical LiDAR system measures the distance to a target by illuminating the target with a pulsed laser beam and measuring the reflected pulse with a sensor such as a detector or array of detectors. The differences in laser return time, wavelength and/or phase may be used to construct a digital three-dimensional (3D) representation of the target. Because of the very high resolution physical features that can be mapped using a narrow laser beam as incident light, liDAR systems are particularly suited for use in sensing applications such as autopilot and high definition map surveying. The pulsed laser beam emitted by a LiDAR system is typically directed in multiple directions to cover the field of view (FOV). For example, the vertical detection angle of a LiDAR system (referred to as the top view angle when the scanned laser beam is directed downward) may vary with the scanning of objects in vertical space. The required detection distance will vary with the vertical detection angle. For example, when the top view angle is small, i.e., the scanned laser beam emitted by LiDAR is nearly horizontal, the distance from the object is long. On the other hand, as the planar angle increases, the distance to the ground becomes shorter. Conventional LiDAR systems use a constant laser emission power for different vertical detection angles. This causes several problems. First, the laser beam reflected by the object at a short distance (e.g., near the ground) may carry a high power and cause saturation at the receiver end, thereby compromising scanning accuracy. The high power resulting increase in operating temperature can degrade the thermal performance of the system. In addition, high power laser beams may pose an eye safety hazard to pedestrians near the LiDAR scanning area. The use of constant power at different vertical angles also compromises the efficiency of the overall system power consumption. Embodiments of the present invention improve the performance of optical sensing systems (e.g., liDAR systems) by implementing dynamic laser power control to compensate for variations in the sensing distance of the sensing system at different vertical sensing angles. Disclosure of Invention Embodiments of the present invention provide an optical sensing system. An exemplary optical sensing system includes an emitter configured to emit a light beam from a plurality of perpendicular detection angles to scan an object. The optical sensing system further includes a controller configured to dynamically vary the emitted power level of the light beam emitted at each vertical detection angle. The optical sensing system further includes a receiver configured to detect the light beam returned by the object. Embodiments of the present invention also provide a method for controlling a transmit power level in an optical sensing system. The method includes scanning an object by emitting a light beam from a plurality of perpendicular detection angles by an emitter. The method further includes dynamically changing, by the controller, the transmit power level of the light beam emitted at each vertical detection angle. The method further includes detecting, by the receiver, the beam returned by the object. The embodiment of the invention also provides a control device for controlling the transmitting power level in the optical sensing system. The control device includes a drive circuit configured to drive the emitter to emit the light beam at a dynamically varying emission power level. The light beam is emitted at a plurality of perpendicular detection angles. The control device further includes a controller configured to control the driving circuit to dynamically change the emission power level of the light beam emitted at each vertical detection angle. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. Drawings FIG. 1 illustrates a schematic view of an exemplary vehicle equipped with a LiDAR system, according to some embodiments of the present disclosure; FIG. 2 illustrates a block diagram of an exemplary LiDAR system, according to some embodiments of the present disclosure; FIG. 3 illustrate