High definition LiDAR system

Abstract

A lidar-based 3-D point cloud measuring system includes a base, a housing, a plurality of photon transmitters and photon detectors contained within the housing, a rotary motor that rotates the housing about the base, and a communication component that allows transmission of signals generated by the photon detectors to external components. In several versions of the invention, the system includes a vertically oriented motherboard, thin circuit boards such as ceramic hybrids for selectively mounting emitters and detectors, a conjoined D-shaped lens array, and preferred firing sequences.

Description

PRIORITY CLAIM FIGS. 19A and 19B illustrate various circuits for driving laser diodes.FIGS. 19A and 19B illustrate circuits used for controlling the firing of a laser diode. With regard to FIGS. 19A and 20, the DSP sends a charge/on signal to a FET 200, thereby charging an inductor 204, which in turn charges a capacitor 206, which in turn causes a laser 210 to fire. The DSP turns off the FET 200 after a predetermined period of time as previously determined by return intensity measurements from the last pulse. The charging pulse is on for ˜5 microseconds and the firing pulse is on for ˜20 nanoseconds. It can be seen that the energy stored in the inductor is ½*L*I{circumflex over ( )}2. When the FET is turned off, this energy is transferred into the discharge capacitor via a diode. The energy in the capacitor is ½*C*V{circumflex over ( )}2. It is apparent then that the voltage that is in the capacitor is proportional to the on duration of the FET. Therefore, the DSP can use a simple algorithm to predict the proper amount of voltage in the capacitor. For example, if the return pulse is ½ as large as desirable, from a noise and measurement accuracy point of view, then the DSP simply charges the inductor for twice as long for the next pulse. Of course, such a system cannot see into the future, so it is not always possible to get the perfect return intensity every time. Nevertheless, the technique works well enough most of the time for the system to benefit from technique.

FIG. 19B includes two FETs. When FET1 is on during a charging pulse (FIG. 20), an inductor 240 charges a capacitor 242. When the FET2 is on during the firing pulse (see FIG. 20), FET2 causes the capacitor 242 to discharge thereby firing a laser diode 244.

FIG. 21 illustrates current and luminance output of the circuits of FIGS. 19A and 19B. FIG. 22 shows digitized sensed values at the photo diode of the receiving side.

While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.

Claims

1. A lidar-based sensor system comprising:

a base;

head assembly;

a rotary component configured to rotate the head assembly with respect to the base, the rotation of the head assembly defining an axis of rotation;

an electrical motherboard carried in the head assembly, the motherboard defining a plane and being positioned substantially parallel to the axis of rotation;

a lens positioned on the head assembly on a first side of the motherboard;

a mirror positioned on the head assembly on a second side of the motherboard;

a plurality of photon transmitters mounted to a plurality of emitter circuit boards, the plurality of emitter circuit boards being mounted directly to the motherboard; and

a plurality of detectors mounted to a plurality of detector circuit boards, the plurality of detector circuit boards being mounted directly to the motherboard.

2. The sensor system of claim 1, wherein

the lens comprises an emitter lens and a detector lens, the emitter lens and the detector lens being positioned adjacent one another; and

the mirror comprises an emitter mirror and a detector mirror;

wherein the emitter mirror is positioned within the head assembly to reflect light from the plurality of photon transmitters through the emitter lens, and the detector mirror is positioned within the head to reflect light received through the detector lens toward the plurality of detectors.

3. The sensor system of claim 2, further comprising a unitary support structure, the motherboard, detector lens, emitter lens, detector mirror, and emitter mirror all being secured to the unitary support structure.

4. The sensor system of claim 2, wherein the plurality of emitters are oriented to transmit light from the second side of the motherboard toward the emitter mirror.

5. The sensor system of claim 4, wherein the motherboard comprises a central opening, the central opening being positioned to allow light from the emitters to pass from emitter mirror through the central opening and toward the emitter lens.

6. The sensor system of claim 5, wherein the central opening is further positioned to allow light to pass from the detector lens through the central opening and toward the detector mirror.

7. The sensor system of claim 2, wherein the plurality of emitter circuit boards are secured to the motherboard to form a first vertical stack.

8. The sensor system of claim 7, wherein the first vertical stack of emitter circuit boards forms an angularly fanned array.

9. The sensor system of claim 7, wherein the plurality of detector circuit boards are secured to the motherboard to form a second vertical stack, the first vertical stack of emitter circuit boards being positioned substantially parallel to the second vertical stack of detector circuit boards.

10. The sensor system of claim 9, wherein the second vertical stack of detector circuit boards forms an angularly fanned array.

11. The sensor system of claim 2, wherein the emitter lens comprises a first D-shaped lens and the detector lens comprises a second D-shaped lens, a respective vertical side of each of the first D-shaped lens and the second D-shaped lens being positioned closely adjacent one another to form a conjoined D-shaped lens array.

12. The sensor system of claim 11, wherein the first D-shaped lens comprises a first plurality of lenses, and wherein the second D-shaped lens comprises a second plurality of lenses.

13. The sensor system of claim 2, wherein the plurality of emitter circuit boards are secured to the motherboard to form a first vertical stack, the first vertical stack being divided into at least two groups of emitters, each of the at least two groups comprising several emitters from the plurality of emitters such that the at least two groups form non-overlapping subsets of the plurality of emitters, the sensor further having a control component to control the firing of the emitters such that one emitter is fired at a time, the control component further causing firing from one of the at least two groups and then the other of the at least two groups in an alternating fashion.

14. The sensor system of claim 13, wherein the at least two groups comprises:

a first group forming a first portion of the first vertical stack and organized sequentially from a first top position to a first bottom position; and

a second group forming a remaining portion of the first vertical stack organized sequentially from a second top position to a second bottom position;

whereby the control component causes firing of the emitters to alternate between the first group and the second group, and further causes firing within the first group to proceed sequentially and firing within the second group to proceed sequentially.

15. The sensor system of claim 2, wherein the rotary component further comprises a capacitive coupler.

16. A lidar-based sensor system comprising:

a base;

head assembly;

a motor configured to rotate the head assembly with respect to the base, the rotation of the head assembly defining an axis of rotation;

an electrical motherboard carried in the head assembly;

a plurality of photon transmitters mounted to a plurality of emitter circuit boards, the plurality of emitter circuit boards being mounted to the motherboard;

a plurality of detectors mounted to a plurality of detector circuit boards, the plurality of detector circuit boards being mounted to the motherboard;

an emitter mirror supported within the head assembly;

a detector mirror supported within the head assembly; and

a conjoined D-shaped lens assembly, the lens assembly forming an emitter portion and a detector portion;

wherein the motherboard is a unitary component for mounting the plurality of emitter circuit boards and the plurality of detector circuit boards, the motherboard being positioned between the emitter mirror and the detector mirror on a first side and the lens assembly on the other side, the motherboard further having an opening to allow light to pass between the lens assembly and either the detector mirror or the emitter mirror;

whereby light transmitted by one of the plurality of emitters is reflected from the emitter mirror and passes through the emitter portion of the lens assembly, and light received by the detector portion of the lens assembly is reflected by the detector mirror and received by one of the plurality of detectors.

17. The sensor system of claim 16, wherein the motherboard defines a plane that is parallel to the axis of rotation.

18. The sensor system of claim 17, further comprising:

a control component for causing the firing of the plurality of emitters; and

further wherein there are n emitters in the plurality of emitters, the n emitters being positioned in a vertical stack from 1 to n, the plurality of emitters being divided into two groups, including a first group of emitters from 1 to n/2 and a second group of emitters from n/2+1 to n; wherein the control component causes the emitters to fire alternatingly between the first group and the second group, and to fire sequentially within each group such that emitter 1 and emitter n/2°1 fire sequentially.

19. A lidar-based sensor system comprising:

a base having a head assembly and a rotary component configured to rotate the head assembly with respect to the base;

a motherboard in the head assembly;

a mirror at a periphery of the head assembly;

a lens at the periphery of the head assembly;

a plurality of transmitters carried on the head assembly for rotation with the head assembly, the plurality of transmitters being positioned to transmit light pulses through the lens;

a plurality of detectors carried on the head assembly for rotation with the head assembly, the plurality of detectors being positioned to receive the light pulses after reflection from a surface;

a processor coupled to a control circuit; and

a memory including processor executable code, wherein the processor executable code, upon execution by the processor, configures the processor to send one or more signals to control the control circuit to cause one of the transmitters to fire.

20. The sensor system of claim 19, wherein the control circuit includes a transistor, an inductor, and a capacitor, and wherein sending the one or more signals to control the control circuit to cause one of the transmitters to fire comprises:

sending a charge/on signal to the transistor to charge the inductor; and

turning off the charge/on signal to transfer energy from the inductor into the capacitor, which causes the one transmitter to fire.

21. The sensor system of claim 20, wherein the charge/on signal is turned off after a period of time that is inversely proportional to the return intensity of the previous light pulse transmitted by the one transmitter.

22. The sensor system of claim 19, wherein the control circuit includes a first transistor, a second transistor, an inductor, and a capacitor, and wherein sending the one or more signals to control the control circuit to cause one of the transmitters to fire comprises:

sending a charge/on signal to the first transistor to cause the inductor to charge the capacitor; and

sending a firing pulse to the second transistor to cause the capacitor to discharge and fire the one transmitter.

23. The sensor system of claim 19, wherein sending the one or more signals to control the control circuit to cause one of the transmitters to fire comprises:

sending the one or more signals to control charging and discharging of a charge storage device of the control circuit, wherein the discharging of the charge storage device causes the one transmitters to fire.

24. A method comprising:

rotating a head assembly of a lidar-based sensor system with respect to a base of the lidar-based sensor system, the lidar-based sensor system having a plurality of transmitters positioned to transmit light pulses and a plurality of detectors positioned to receive the light pulses after reflection from a surface, the plurality of transmitters being mounted to a respective plurality of transmitter circuit boards, the plurality of detectors being mounted to a respective plurality of receiver circuit boards, the pluralities of transmitter circuit boards and detector circuit boards being mounted to a motherboard of the lidar-based sensor system; and

controlling charging and discharging of a plurality of charge storage devices corresponding to the plurality of transmitters, wherein the discharging of the charge storage devices causes the respective transmitters to fire.