Robust eye-safe methods, systems, devices, and storage media for LiDAR

Abstract

The present invention relates to a robust eye-safe method, system, device, and storage medium for LiDAR. Systems and techniques for LiDAR (light detection and ranging) safety measures are described. The described techniques include receiving, at a spin cell of a LiDAR, a command from a base cell to start a laser; obtaining, at the spin cell, a measurement from a sensor for detecting rotation of the spin cell in a rotation plane; determining, at the spin cell, based on the measurement, whether a rotational speed of the spin cell is greater than or equal to a minimum rotational speed threshold; and starting, at the spin cell, the laser to produce an output in response to the command based on the determination that the rotational speed of the spin cell is greater than or equal to the minimum rotational speed threshold.

Description

TECHNICAL FIELD

[0001] The present application relates to LiDAR (Light Detection and Ranging) technology. BACKGROUND

[0002] LiDAR is a technology that uses lasers and imaging circuitry to obtain data about physical objects within its line of sight. A LiDAR system can produce LiDAR data. LiDAR data can include a collection of three-dimensional (3D) or two-dimensional (2D) points used to construct a representation of an environment surrounding the LiDAR system. SUMMARY

[0003] According to an aspect of the present application, an apparatus comprising: a laser, wherein the apparatus is configured to cause the laser to rotate in a rotation plane; a sensor to detect rotation of the apparatus in the rotation plane; and a control circuit configured to: receive a command to activate the laser, determine whether a rotational speed of the apparatus is greater than or equal to a minimum rotational speed threshold based on an output of the sensor, and activate the laser to produce an output in response to the command based on a determination that the rotational speed of the apparatus is greater than or equal to the minimum rotational speed threshold.

[0004] According to another aspect of the present application, a system comprising: a spin unit comprising a laser, the spin unit configured to cause the laser to rotate in a rotation plane; and a base unit coupled with the spin unit, the base unit comprising a motor to cause the spin unit to rotate in the rotation plane and a processor configured to send a command to activate the laser, wherein the spin unit further comprises: a sensor to detect rotation of the spin unit in the rotation plane; and a control circuit configured to: receive the command to activate the laser, determine whether a rotational speed of the spin unit is greater than or equal to a minimum rotational speed threshold based on an output of the sensor, and activate the laser to produce an output in response to the command based on a determination that the rotational speed of the spin unit is greater than or equal to the minimum rotational speed threshold.

[0005] According to another aspect of the present application, a method comprising: transmitting, from a base unit of a LIDAR system, a command to start a laser of a spin unit of the LIDAR system, the spin unit configured to cause the laser to rotate in a rotation plane; receiving, at the spin unit, the command to start the laser; obtaining, at the spin unit, a measurement from a sensor for detecting rotation of the spin unit in the rotation plane; determining, at the spin unit, based on the measurement, whether a rotational speed of the spin unit is greater than or equal to a minimum rotational speed threshold; and starting, at the spin unit, the laser to produce an output in response to the command based on a determination that the rotational speed of the spin unit is greater than or equal to the minimum rotational speed threshold.

[0006] According to another aspect of the present application, a non-transitory computer readable storage medium comprising at least one program for execution by at least one processor of an apparatus, the at least one program comprising instructions that, when executed by the at least one processor, cause the apparatus to perform the above method. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 An example of an autonomous vehicle with autonomous capabilities is shown.

[0008] Figure 2 A computer system is shown.

[0009] Figure 3 An example architecture of an autonomous vehicle is shown.

[0010] Figure 4 An example of inputs and outputs that a perception module can use is shown.

[0011] Figure 5 An example of a LiDAR system is shown.

[0012] Figure 6 A LiDAR system in operation is shown.

[0013] Figure 7 Additional details of the operation of a LiDAR system are shown.

[0014] Figure 8 An example of an architecture of a LiDAR system including a spin unit and a base unit is shown.

[0015] Figure 9 An example of an architecture of a LiDAR base unit is shown.

[0016] Figure 10 An example of an architecture of a LiDAR spin unit is shown.

[0017] Figure 11Another example showing an architecture of a LiDAR spin cell.

[0018] Figure 12 A flowchart of an example of a process to perform a safety check before starting a laser of a LiDAR. DETAILED DESCRIPTION

[0019] In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present application. It will be apparent, however, to one skilled in the art that the present application can be practiced without some or all of these specific details. In other instances, well known structures and devices are not shown in order to avoid obscuring the application.

[0020] In the drawings, specific arrangements or orders of schematic elements (such as those representing devices, modules, instruction blocks, and data elements) are shown for ease of description. However, one skilled in the art will understand that the specific order or arrangement of the schematic elements shown in the drawings is not intended to imply a particular processing order or sequence, or separation of the processing processes. Furthermore, inclusion of a schematic element in the drawings is not intended to mean that such element is required in all embodiments, nor is it intended to mean that the features represented by such element cannot be included in some embodiments or combined with other elements in some embodiments.

[0021] Furthermore, in the drawings, connecting elements, such as solid or dashed lines or arrows, are used to illustrate connections, relationships or associations between two or more other schematic elements, and the absence of any such connecting elements is not intended to imply that a connection, relationship or association cannot exist between one or more elements. In other words, connections, relationships or associations between some elements are not shown in the drawings to not obscure the disclosure. Furthermore, multiple connections, relationships or associations between elements are represented by a single connecting element for ease of illustration. For example, if a connecting element represents a communication of signals, data or instructions, one skilled in the art will appreciate that such element represents one or more signal paths (e.g., a bus) through which the communication might take place.

[0022] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description of embodiments, numerous specific details are set forth in order to provide a thorough understanding of the various described embodiments. However, it will be apparent to one skilled in the art that the various described embodiments can be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

[0023] Each of the several features described below can be used independently of each other, or with any combination of other features. However, any individual feature can not solve any of the problems discussed above, or can only solve one of the problems discussed above. Some of the problems discussed above can not be fully addressed by any one feature described herein. Although a heading is provided, information related to a particular heading can also be found elsewhere in the specification. Embodiments are described herein according to the following summary:

[0024] 1. OVERALL SUMMARY

[0025] 2. SYSTEM SUMMARY

[0026] 3. AUTONOMOUS VEHICLE ARCHITECTURE

[0027] 4. AUTONOMOUS VEHICLE INPUT

[0028] 5. LiDAR SAFETY MECHANISMS

[0029] OVERALL SUMMARY

[0030] Spin-type LiDAR technology performs a 360-degree scan by continuously rotating a spinning unit of a LiDAR that contains a laser and an optical sensor. This application includes techniques and systems for laser safety measures for such technology, including safety measures that ensure that the spinning unit of a LiDAR is greater than or equal to a minimum rotational speed before operating a laser according to commands from a base unit of the LiDAR, or pausing laser operation in the event that the unit causes the spin to slow down or stop. One or more of the described techniques and systems can use a low-cost rotational detection sensor (e.g., a gyroscope) within the spinning unit to determine that the minimum rotational speed is met before starting the laser.

[0031] Spin-type LiDARs generally employ lasers with power outputs that can be harmful to the human eye and sensitive electronic devices such as digital cameras if the spinning unit stops spinning. For example, for a 1550 nanometer wavelength, the spinning laser is considered safe to the human eye and thus meets federal and industry safety guidelines. However, if the laser stops spinning and continuously emits in one particular direction, the laser can cause eye injuries.

[0032] The techniques and systems described herein are able to automatically prevent or pause laser operation when the spin unit of the LiDAR is not spinning fast enough to prevent eye injury. The techniques and systems enable the spin unit of the LiDAR to be used as a final safety measure for laser operation to ensure that the laser operates (e.g., produces light) only when the unit is spinning at a safe rate. The techniques and systems are able to protect against faulty or safety-compromised LiDAR base units that can command the spin unit to start the laser without spinning the spin unit. The techniques and systems are able to be implemented within a spin unit that uses low-cost inertial sensors. The techniques and systems are able to be implemented in hardware that minimizes or eliminates unauthorized tampering.

[0033] System Overview

[0034] Figure 1 An example of an autonomous vehicle 100 with autonomous capabilities is shown.

[0035] As used herein, the term“autonomous capabilities” refers to a function, feature, or facility that enables a vehicle to operate, in part or in whole, without real-time human intervention, including but not limited to fully autonomous vehicles, highly autonomous vehicles, and conditional autonomous vehicles.

[0036] As used herein, an autonomous vehicle (AV) is a vehicle with autonomous capabilities.

[0037] As used herein, a“vehicle” includes a means of transporting goods or people. For example, a car, bus, train, airplane, drone, truck, boat, ship, submersible, spacecraft, etc. A self-driving car is an example of a vehicle.

[0038] As used herein, a“trajectory” refers to a path or route that navigates an AV from a first spatiotemporal location to a second spatiotemporal location. In embodiments, the first spatiotemporal location is referred to as an initial or starting location, and the second spatiotemporal location is referred to as a destination, final location, target, target location, or target location. In some examples, a trajectory is composed of one or more segments (e.g., sections of a road), and each segment is composed of one or more blocks (e.g., a portion of a lane or intersection). In embodiments, spatiotemporal locations correspond to real-world locations. For example, a spatiotemporal location is a pickup or drop-off location for a person or cargo to board or disembark.

[0039] As used herein, a “sensor(s)” includes one or more hardware components for detecting information related to the sensor’s surrounding environment. Some hardware components can include sensing components (e.g., image sensors, biometric sensors), transmission and / or reception components (e.g., laser or radio frequency wave emitters and receivers), electronic components such as analog-to-digital converters, data storage devices such as RAM and / or non-volatile memory, software or firmware components, and data processing components such as application-specific integrated circuits, microprocessors, and / or microcontrollers.

[0040] As used herein, a “scene description” is a data structure (e.g., a list) or data stream that includes one or more classified or labeled objects detected by one or more sensors on an AV or one or more classified or labeled objects provided by a source external to the AV.

[0041] As used herein, a “roadway” is a physical area that can be traversed by a vehicle, and can correspond to a named thoroughfare (e.g., a city street, an interstate highway, etc.) or can correspond to an unnamed thoroughfare (e.g., a driveway within a house or office building, a section of a parking lot, a section of an empty parking lot, a dirt path in a rural area, etc.). Because some vehicles (e.g., four-wheel drive pickup trucks, sport utility vehicles (SUVs), etc.) are capable of traversing a variety of physical areas that are not particularly well-suited for vehicle travel, a “roadway” can be any physical area that has not been formally defined as a thoroughfare by a municipality or other governmental or administrative body.

[0042] As used herein, a "lane" is a portion of a roadway that can be traversed by a vehicle. Sometimes a lane is identified based on lane markings. For example, a lane can correspond to most or all of the space between lane markings, or only a portion (e.g., less than 50%) of the space between lane markings. For example, a roadway with lane markings far apart can accommodate two or more vehicles such that one vehicle can pass another without crossing a lane marking, and thus can be interpreted as a lane being narrower than the space between lane markings, or two lanes between lanes. Lanes can also be interpreted in the absence of lane markings. For example, a lane can be defined based on physical features of the environment (e.g., rocks in a rural area and trees along a boulevard, or natural obstacles that should be avoided, e.g., in underdeveloped areas). Lanes can also be interpreted independent of lane markings or physical features. For example, a lane can be interpreted based on an arbitrary path in an area that lacks obstacles that would otherwise lack features that would be interpreted as lane boundaries. In an example scenario, an AV can interpret a lane through an unobstructed portion of a field or open space. In another example scenario, an AV can interpret a lane through a wide (e.g., wide enough for two or more lanes) roadway that lacks lane markings. In this scenario, the AV can communicate information about the lane to other AVs so that the other AVs can use the same lane information to coordinate path planning between the AVs.

[0043] "one or more" includes a function performed by a single element, a function performed by a plurality of elements, e.g., in a distributed manner, a plurality of functions performed by a single element, a plurality of functions performed by a plurality of elements, or any combination of the above.

[0044] It will also be understood that, although the terms "first," "second," etc. can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact could be termed a second contact, and, similarly, a second contact could be termed a first contact, without departing from the scope of the various described embodiments. The first contact and the second contact are both contacts, but they are not the same contact.

[0045] The terminology used in the description of the various embodiments described herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or," as used herein, refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms "comprises," "comprising," "includes," "including," "has," "having," "has" and / or "having," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0046] As used herein, the term "if' can be construed to mean "when" or "when a" or "in response to a determination that" or "in response to a detection that" depending on the context. Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" can be construed to mean "upon a determination" or "in response to a determination" or "upon detecting [a stated condition or event]" or "in response to detecting [a stated condition or event]" depending on the context.

[0047] As used herein, an AV system refers to an array of AVs and hardware, software, stored data, and real-time generated data that support operation of the AVs. In embodiments, the AV system is incorporated within the AVs. In embodiments, the AV system is distributed across several locations.

[0048] In general, this document describes techniques applicable to any vehicle having one or more autonomous capabilities, including fully autonomous vehicles, highly autonomous vehicles, and conditionally autonomous vehicles, such as so-called Level 5, Level 4, and Level 3 vehicles, respectively (see SAE International Standard J3016: Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles, incorporated herein by reference in its entirety for more detailed information on levels of vehicle autonomy). The techniques described in this document are also applicable to partially autonomous vehicles and driver-assist vehicles, such as so-called Level 2 and Level 1 vehicles (see SAE International Standard J3016: Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles). In embodiments, one or more Level 1, Level 2, Level 3, Level 4, and Level 5 vehicle systems can automatically perform certain vehicle operations (e.g., steering, braking, and use of a map) under certain operating conditions based on processing of sensor inputs. The techniques described in this document can benefit vehicles at any level ranging from fully autonomous vehicles to human-operated vehicles.

[0049] Autonomous vehicles have advantages over vehicles that require human drivers. One advantage is safety. For example, in 2016, the United States experienced 6 million car accidents, 2.4 million people injured, 40,000 people killed, and 13 million vehicle crash incidents, with an estimated societal cost of $910 billion. From 1965 to 2015, the number of traffic fatalities per 100 million miles traveled in the United States has decreased from about 6 to about 1, in part due to additional safety measures deployed in vehicles. For example, an extra half-second warning associated with an impending collision is believed to mitigate 60% of rear-end collisions. However, passive safety features (e.g., seat belts, airbags) can have reached their limit in improving this number. Thus, active safety measures such as automated control of a vehicle are a possible next step in improving these statistics. Since human drivers are believed to be responsible for 95% of serious pre-crash events in collisions, automated driving systems can achieve better safety outcomes by, for example, reliably identifying and avoiding emergencies better than humans; making better decisions than humans, obeying traffic laws better than humans, and predicting future events better than humans; and reliably controlling the vehicle better than humans.

[0050] Reference Figure 1 The AV system 120 causes the vehicle 100 to operate along a trajectory 198 through the environment 190 to a destination 199 (sometimes referred to as a final location) while avoiding objects (e.g., natural obstacles 191, vehicles 193, pedestrians 192, cyclists, and other obstacles) and obeying road rules (e.g., operating rules or driving preferences).

[0051] In embodiments, the AV system 120 includes a device 101 for receiving and operating on operational commands from the computer processor 146. The term "operational command" is used to denote an executable instruction (or set of instructions) that causes the vehicle to take an action (e.g., a driving maneuver). Operational commands can include, without limitation, instructions for causing the vehicle to start moving forward, stop moving forward, start moving backward, stop moving backward, accelerate, decelerate, make a left turn, and make a right turn. In embodiments, the computer processor 146 is similar to the processor 204 described below with reference to FIG. 2. Examples of the device 101 include a steering controller 102, a brake 103, a gear, an accelerator pedal or other acceleration control mechanism, a windshield wiper, a side door lock, a window control, and a turn signal indicator. Figure 2

[0052] ​In an embodiment, the AV system 120 includes sensors 121 for measuring or inferring attributes of the state or condition of the vehicle 100, such as the AV's position, linear velocity and angular velocity, linear acceleration and angular acceleration, and heading (e.g., the direction of the front end of the vehicle 100). Examples of sensors 121 are GPS, inertial measurement units (IMUs) that measure both linear acceleration and angular rate of the vehicle, wheel rate sensors for measuring or estimating wheel slip ratio, wheel braking pressure or braking torque sensors, engine torque or wheel torque sensors, and steering angle and angular rate sensors.

[0053] In an embodiment, sensor 121 also includes sensors for sensing or measuring properties of the AV's environment. Examples include a monocular or stereo camera 122 with visible, infrared, or thermal (or both) spectra, a LiDAR 123, a RADAR, an ultrasonic sensor, a time-of-flight (TOF) depth sensor, a rate sensor, a temperature sensor, a humidity sensor, and a precipitation sensor.

[0054] In one embodiment, the AV system 120 includes a data storage unit 142 and a memory 144 for storing machine instructions associated with a computer processor 146 or data collected by the sensor 121. In another embodiment, the data storage unit 142 is associated with the following... Figure 2 The described ROM 208 or storage device 210 is similar. In this embodiment, memory 144 is similar to main memory 206 described below. In this embodiment, data storage unit 142 and memory 144 store historical, real-time, and / or predictive information about environment 190. In this embodiment, the stored information includes maps, driving performance, traffic congestion updates, or weather conditions. In this embodiment, data related to environment 190 is transmitted from remote database 134 to vehicle 100 via a communication channel.

[0055] In embodiments, the AV system 120 includes communication devices 140 for transmitting properties of other vehicles' states and conditions, such as position, linear and angular velocity, linear and angular acceleration, and linear and angular heading, measured or inferred to the vehicle 100. These devices include vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communication devices and devices for wireless communication over point-to-point or ad hoc networks or both. In embodiments, the communication devices 140 communicate across the electromagnetic spectrum, including radio and optical communications, or other media (e.g., air and acoustic media). The combination of vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I) communication (and, in some embodiments, one or more other types of communication) is sometimes referred to as vehicle-to-everything (V2X) communication. V2X communication is generally in compliance with one or more communication standards for communication with and between autonomous vehicles.

[0056] In embodiments, the communication devices 140 include a communication interface. For example, a wired, wireless, WiMAX, Wi-Fi, Bluetooth, satellite, cellular, optical, near field, infrared, or radio interface. The communication interface transmits data from the remote database 134 to the AV system 120. In embodiments, the remote database 134 also stores and transmits digital data (e.g., storing data such as road and street locations). This data is stored in memory 144 on the vehicle 100 or transmitted from the remote database 134 to the vehicle 100 over a communication channel.

[0057] In embodiments, the remote database 134 stores and transmits historical information related to driving properties (e.g., velocity and acceleration profiles) of vehicles that have previously traveled along the trajectory 198 at a similar time of day. In one implementation, this data can be stored in memory 144 on the vehicle 100 or transmitted from the remote database 134 to the vehicle 100 over a communication channel.

[0058] The computer processor 146 located on the vehicle 100 generates control actions algorithmically based on both real-time sensor data and a priori information, allowing the AV system 120 to perform its autonomous driving capabilities.

[0059] In embodiments, the AV system 120 includes computer peripherals 132 coupled to the computer processor 146 for providing information and alerts to a user (e.g., an occupant or a remote user) of the vehicle 100 and receiving input from the user. In embodiments, the peripherals 132 are similar to those described below with reference to FIG. 2. Figure 2The display 212, input device 214, and cursor control 216 are discussed. The coupling is wireless or wired. Any two or more of the interface devices can be integrated into a single device.

[0060] In embodiments, the AV system 120 receives and enforces a privacy level of the occupant, for example, specified by the occupant or stored in a profile associated with the occupant. The privacy level of the occupant determines how the use of certain information associated with the occupant (e.g., occupant comfort data, biometric data, etc.) stored in the occupant profile and / or stored on the cloud server 136 and associated with the occupant profile is permitted. In embodiments, the privacy level specifies certain information associated with the occupant that is deleted upon completion of the ride. In embodiments, the privacy level specifies certain information associated with the occupant and identifies one or more entities that are authorized to access the information. Examples of the specified entities that are authorized to access the information can include other AVs, third-party AV systems, or any entity that can potentially have access to the information.

[0061] The privacy level of the occupant can be specified at one or more levels of granularity. In embodiments, the privacy level identifies certain information that is to be stored or shared. In embodiments, the privacy level applies to all information associated with the occupant, such that the occupant can specify that her personal information is not stored or shared. The specification of entities that are permitted to access certain information can also be specified at various levels of granularity. The various sets of entities that are permitted to access certain information can include, for example, other AVs, the cloud server 136, certain third-party AV systems, etc.

[0062] In embodiments, the AV system 120 or the cloud server 136 determines whether certain information associated with the occupant is accessible to the AV 100 or another entity. For example, a third-party AV system attempting to access occupant input related to a certain spatiotemporal location must obtain authorization, for example, from the AV system 120 or the cloud server 136, to access information associated with the occupant. For example, the AV system 120 uses the specified privacy level of the occupant to determine whether occupant input related to a spatiotemporal location can be presented to a third-party AV system, the AV 100, or another AV. This enables the privacy level of the occupant to specify which other entities are permitted to receive data related to the actions of the occupant or other data associated with the occupant.

[0063] Figure 2A computer system 200 is shown. In implementations, the computer system 200 is a special-purpose computing device. The special-purpose computing device is either hard-wired to perform the techniques, or includes digital electronic devices such as one or more application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) that are persistently programmed to perform the techniques, or one or more general purpose hardware processors programmed to perform the techniques pursuant to program instructions in firmware, memory, other storage, or a combination. Such special-purpose computing devices can also combine custom hard-wired logic, ASICs, or FPGAs with custom programming to accomplish the techniques. In various embodiments, the special-purpose computing device is a desktop computer system, a portable computer system, a handheld device, a network device, or any other device that incorporates hard-wired and / or program logic to implement the techniques.

[0064] In an embodiment, the computer system 200 includes a bus 202 or other communication mechanism for communicating information, and a processor 204 coupled with bus 202 for processing information. The processor 204 is, for example, a general-purpose microprocessor. The computer system 200 also includes a main memory 206, such as a random access memory (RAM) or other dynamic storage device, coupled to bus 202 for storing information and instructions to be executed by processor 204. In one implementation, the main memory 206 is used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 204. The computer system 200 can further include a read only memory (ROM) 208 or other static storage device coupled to bus 202 for storing static information and instructions for processor 204. A storage device 210, such as a magnetic disk, optical disk, solid-state drive, or three-dimensional crosspoint memory, is provided and coupled to bus 202 for storing information and instructions.

[0065] In an embodiment, the computer system 200 also includes a read only memory (ROM) 208 or other static storage device coupled to bus 202 for storing static information and instructions for processor 204. A storage device 210, such as a magnetic disk, optical disk, solid-state drive, or three-dimensional crosspoint memory, is provided and coupled to bus 202 for storing information and instructions.

[0066] In embodiments, the computer system 200 is coupled via the bus 202 to a display 212, such as a cathode ray tube (CRT), liquid crystal display (LCD), plasma display, light-emitting diode (LED) display, or organic light-emitting diode (OLED) display for displaying information to a computer user. An input device 214, including alphanumeric and other keys, is coupled to the bus 202 for communicating information and command selections to the processor 204. Another type of user input device is a cursor control 216, such as a mouse, a trackball, a touchscreen, or cursor direction keys for communicating direction information and command selections to the processor 204 and for

[0067] According to one embodiment, the techniques herein are performed by the computer system 200 in response to the processor 204 executing one or more sequences of one or more instructions contained in the main memory 206. Such instructions can be read into the main memory 206 from another storage medium, such as the storage device 210. Execution of the sequences of instructions contained in the main memory 206 causes the processor 204 to perform the process steps described herein. In alternative embodiments, hard-wired circuitry can be used in place of or in combination with software instructions.

[0068] The term “storage media” as used herein refers to any non-transitory media that store data and / or instructions that cause a machine to operate in a specific fashion. Such storage media include non-volatile media and / or volatile media. Non-volatile media include, for example, optical disks, magnetic disks, solid-state drives, or three-dimensional cross-point memory such as the storage device 210. Volatile media include dynamic memory, such as the main memory 206. Common forms of storage media include, for example, a floppy disk, a flexible disk, a hard disk, a solid- state drive, magnetic tape, or any other magnetic data storage medium, a CD-ROM, any other optical data storage medium, any physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, an NV-RAM, or any other memory chip or cartridge.

[0069] Storage media are distinct from, but can be used in combination with, transmission media. Transmission media participate in transferring information between storage media. For example, transmission media include coaxial cables, copper wire, and fiber optic cables, including the wires that comprise the bus 202. Transmission media can also take the form of acoustic or light waves, such as those generated during radio frequency and infrared data communications.

[0070] In embodiments, various forms of media are involved in carrying one or more sequences of one or more instructions to processor 204 for execution. For example, the instructions are initially carried on a magnetic disk or solid state drive of a remote computer. The remote computer loads the instructions into its dynamic memory and sends the instructions over a telephone line using a modem. A local modem in computer system 200 receives the data on the telephone line and uses an infrared transmitter to convert the data to an infrared signal. An infrared detector receives the data carried in the infrared signal and appropriate circuitry places the data on bus 202. Bus 202 carries the data to main memory 206, from which processor 204 retrieves and executes the instructions. The instructions received by main memory 206 can optionally be stored on storage device 210 either before or after execution by processor 204.

[0071] Computer system 200 also includes a communication interface 218 coupled to bus 202. Communication interface 218 provides a two-way data communication coupling to a network link 220 that is connected to a local network 222. For example, communication interface 218 is a integrated services digital network (ISDN) card, cable modem, satellite modem, or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface 218 is a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links are also implemented in some implementations. In any such implementation, communication interface 218 sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0072] Network link 220 typically provides data communication through one or more networks to other data devices. For example, network link 220 provides a connection through local network 222 to a host computer 224 or to cloud data centers or devices operated by an Internet Service Provider (ISP) 226. ISP 226 in turn provides data communication services through the world wide packet data communication network now commonly referred to as the "Internet" 228. Local network 222 and Internet 228 both use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on network link 220 and through communication interface 218, which carry the digital data to and from computer system 200, are example forms of transmission media for digital data.

[0073] Computer system 200 sends messages and receives data, including program code, through the network(s), network link 220 and communication interface 218. In embodiments, computer system 200 receives code at a remote and / or local storage facility. The received code is executed by processor 204 as it is received, and / or stored in storage device 210, or other non-volatile storage for later execution.

[0074] Autonomous vehicle architecture

[0075] Figure 3 An example architecture 300 is shown for an autonomous vehicle (e.g., the vehicle 100 shown. Figure 1 The architecture 300 includes a perception module 302 (sometimes referred to as perception circuitry), a planning module 304 (sometimes referred to as planning circuitry), a control module 306 (sometimes referred to as control circuitry), a localization module 308 (sometimes referred to as localization circuitry), and a database module 310 (sometimes referred to as database circuitry). The modules each play a role in the operation of the vehicle 100. Collectively, the modules 302, 304, 306, 308, and 310 can be an autonomous vehicle system 120. In some embodiments, any of the modules 302, 304, 306, 308, and 310 is a combination of computer software (e.g., executable code stored on a computer-readable medium) and computer hardware (e.g., one or more microprocessors, microcontrollers, application-specific integrated circuits (ASICs), hardware memory devices, other types of integrated circuits, other types of computer hardware, or a combination of any or all of these). Each of the modules 302, 304, 306, 308, and 310 is sometimes referred to as processing circuitry (e.g., computer hardware, computer software, or a combination of the two). A combination of any or all of the modules 302, 304, 306, 308, and 310 is also an example of processing circuitry. Figure 1

[0076] In use, the planning module 304 receives data representing a destination 312 and determines data representing a trajectory 314 (sometimes referred to as a route) that the vehicle 100 can travel in order to reach (e.g., arrive at) the destination 312. To cause the planning module 304 to determine the data representing the trajectory 314, the planning module 304 receives data from the perception module 302, the localization module 308, and the database module 310.

[0077] The perception module 302 uses one or more sensors 121, e.g., also as shown in FIG. 1, to identify physical objects in the vicinity. The objects are classified (e.g., grouped into types such as pedestrians, bicycles, cars, traffic signs, etc.) and a scene description including the classified objects 316 is provided to the planning module 304. Figure 1

[0078] ​​The planning module 304 also receives data representing the location 318 of the AV from the positioning module 308. The positioning module 308 determines the location of the AV by calculating location using data from sensor 121 and data (e.g., geographic data) from database module 310. For example, the positioning module 308 uses data from GNSS (Global Navigation Satellite System) sensors and geographic data to calculate the longitude and latitude of the AV. In embodiments, the data used by the positioning module 308 includes high-precision maps with lane geometry properties, maps describing road network connectivity properties, maps describing lane physical properties (such as traffic speed, traffic volume, number of vehicle and bicycle lanes, lane width, lane traffic direction, or lane marking type and location, or combinations thereof), and maps describing the spatial locations of road features (such as intersections, traffic signs, or various types of other traffic signals). In embodiments, the high-precision map is constructed by adding data to a low-precision map via automatic or manual annotation.

[0079] The control module 306 receives data representing trajectory 314 and data representing AV position 318, and operates the AV control functions 320a-320c (e.g., steering, throttle, braking, ignition) in a manner that will cause the vehicle 100 to travel along trajectory 314 to reach destination 312. For example, if trajectory 314 includes a left turn, the control module 306 will operate the control functions 320a-320c in such a way that the steering angle of the steering function will cause the vehicle 100 to turn left, and the throttle and brake will cause the vehicle 100 to pause and wait for passing pedestrians or vehicles before making the turn.

[0080] Autonomous vehicle input

[0081] Figure 4 The sensing module 302 is shown. Figure 3 The inputs used are 402a-402d (e.g., Figure 1 Examples of sensor 121 and outputs 404a-404d (e.g., sensor data) are shown. One input 402a is a LiDAR (light detection and ranging) system (e.g., Figure 1 The LiDAR system shown is 123. LiDAR is a technique that uses laser light (e.g., a beam of light such as infrared light or other optical waveforms) to obtain data related to physical objects in its line of sight. The LiDAR system produces LiDAR data as output 404a. For example, LiDAR data is a collection of 3D or 2D points (also called point clouds) used to construct a representation of environment 190.

[0082] Another input 402b is a RADAR (Radar) system. RADAR is a technology that uses radio waves to obtain data about nearby physical objects. RADAR can obtain data about objects that are not in the line of sight of the LiDAR system. The RADAR system produces RADAR data as output 404b. For example, the RADAR data is one or more radio frequency electromagnetic signals used to construct the representation of the environment 190.

[0083] Another input 402c is a camera system. The camera system uses one or more cameras (e.g., digital cameras that use a photosensor such as a charge-coupled device [CCD]) to acquire information about nearby physical objects. The camera system produces camera data as output 404c. The camera data is often in the form of image data (e.g., data in an image data format such as RAW, JPEG, PNG, etc.). In some examples, the camera system has multiple independent cameras, e.g., for the purpose of stereoscopic imagery (stereo vision), which enables the camera system to perceive depth. Although the objects perceived by the camera system are described here as being "nearby," this is relative to the AV. In some embodiments, the camera system is configured to "see" objects that are far away (e.g., up to 1 kilometer or more in front of the AV). Thus, in some embodiments, the camera system has features such as sensors and lenses that are optimized for perceiving objects that are far away.

[0084] Another input 402d is a traffic light detection (TLD) system. The TLD system uses one or more cameras to obtain information about traffic lights, street signs, and other physical objects that provide visual navigational information. The TLD system produces TLD data as output 404d. The TLD data is often in the form of image data (e.g., data in an image data format such as RAW, JPEG, PNG, etc.). The TLD system differs from a system that contains a camera in that the TLD system uses a camera with a wide field of view (e.g., using a wide-angle lens or a fisheye lens) to obtain information about as many physical objects that provide visual navigational information as possible, so that the vehicle 100 has access to all relevant navigational information provided by those objects. For example, the TLD system has a field of view of about 120 degrees or more.

[0085] In some embodiments, the outputs 404a-404d are combined using sensor fusion techniques. Thus, the individual outputs 404a-404d are provided to other systems of the vehicle 100 (e.g., to the perception system 106, the planning system 108, and / or the control system 110) as well as to the environment representation system 102. Figure 3The planning module 304) shown, or can provide the combined output to other systems in the form of a single combined output or multiple combined outputs of the same type (e.g., using the same combination technique or combining the same outputs or both) or a single combined output or multiple combined outputs of different types (e.g., using different respective combination techniques or combining different respective outputs or both). In some embodiments, an early fusion technique is used. Early fusion techniques are characterized by combining the outputs before applying one or more data processing steps to the combined output. In some embodiments, a late fusion technique is used. Late fusion techniques are characterized by combining the outputs after applying one or more data processing steps to the individual outputs.

[0086] Figure 5 An example of a LiDAR system 502 is shown (e.g., Figure 4 The LiDAR system 502 emits light 504a-504c from a light emitter 506 (e.g., a laser emitter). The light emitted by the LiDAR system is typically not in the visible spectrum; for example, infrared light is often used. Some of the emitted light 504b encounters a physical object 508 (e.g., a vehicle) and reflects back to the LiDAR system 502. (Light emitted from the LiDAR system typically does not penetrate physical objects, e.g., physical objects in solid form.) The LiDAR system 502 also has one or more light detectors 510 for detecting the reflected light. In embodiments, one or more data processing systems associated with the LiDAR system generate an image 512 representing the field of view 514 of the LiDAR system. The image 512 includes information representing the boundary 516 of the physical object 508. In this way, the image 512 is used to determine the boundary 516 of one or more physical objects in the vicinity of the AV.

[0087] Figure 6 A LiDAR system 502 in operation is shown. In the context shown in this figure, the vehicle 100 receives both the camera system output 404c in the form of an image 602 and the LiDAR system output 404a in the form of LiDAR data points 604. In use, the data processing systems of the vehicle 100 compare the image 602 to the data points 604. In particular, the physical object 606 identified in the image 602 is also identified in the data points 604. In this way, the vehicle 100 perceives the boundary of the physical object based on the contours and density of the data points 604.

[0088] Figure 7Additional details of the operation of LiDAR system 502 are shown. As described above, vehicle 100 detects the boundaries of physical objects based on the characteristics of the data points detected by LiDAR system 502. In embodiments, LiDAR system 502 can be mounted to the top of vehicle 100 and scan 360 degrees around it. During the scan, the lasers of LiDAR system 502 spin on a plane of rotation to make a continuous 360 degree scan. The scan output can be used to detect other vehicles, ground 702, objects 708, and pedestrians 715. As shown, flat objects such as ground 702 will reflect light 704a-704d emitted from LiDAR system 502 in a consistent manner. In other words, since LiDAR system 502 emits light using a consistent spacing, ground 702 will reflect the light back to LiDAR system 502 at the same consistent spacing. As vehicle 100 drives on ground 702, in the absence of anything blocking the road, LiDAR system 502 will continue to detect light reflected by the next valid ground point 706. However, if object 708 blocks the road, light 704e-704f emitted by LiDAR system 502 will be reflected from points 710a-710b in a manner that is inconsistent with the expected consistent manner. From this information, vehicle 100 can determine that object 708 is present. Figure 7

[0089] LiDAR safety mechanism

[0090] Figure 8 An example of the architecture of LiDAR system 800 including spin unit 801 and base unit 852 is shown. LiDAR system 800 can be coupled with a vehicle such as vehicle 100. However, LiDAR system 800 can also be a standalone system that does not require a vehicle, such as a system used in a portable mapping system. In this example, spin unit 801 is mechanically coupled with base unit 852 via shaft 803 such that base unit 852 can rotate spin unit 801 via shaft 803. Other types of coupling are also possible.

[0091] Figure 9 An example of the architecture of LiDAR system 800 including spin unit 801 and base unit 852 is shown. LiDAR system 800 can be coupled with a vehicle such as vehicle 100. However, LiDAR system 800 can also be a standalone system that does not require a vehicle, such as a system used in a portable mapping system. In this example, spin unit 801 is mechanically coupled with base unit 852 via shaft 803 such that base unit 852 can rotate spin unit 801 via shaft 803. Other types of coupling are also possible. Figure 8 ​An example of the architecture of the LiDAR base unit 852 is provided. The base unit 852 may include a processor module 867, a communication module 865, a wireless power module 861, a motor and motor control module 860, and a wireless transceiver 863. The processor module 867 may include one or more ASICs, FPGAs, processors, or combinations thereof. The wireless power module 861 of the base unit 852 can power the spin unit 801. The base unit 852 can communicate with the spin unit 801 via the wireless transceiver 863 through an interface such as Wi-Fi (e.g., IEEE 802.11), Bluetooth, optical, or other types of interfaces. This interface may be based on a common standard such as 802.11 or Bluetooth, or it may be based on a proprietary design. Other types of interfaces are also possible.

[0092] The communication module 865 can communicate with an external source, such as the vehicle 100, using a wireless or wired interface. The processor module 867 can receive commands from the external source to begin imaging. The processor module 867 can cause the motor and motor control module 860 to begin spinning the spin unit 801 and subsequently send commands to the spin unit 801 to activate its laser. The processor module 867 can process image data from the spin unit 801 and relay that data to the external source.

[0093] Figure 10 Show Figure 8 An example of the architecture of a LiDAR spin unit 801 is provided. The spin unit 801 may include control circuitry 830, a rotation sensor 824, a wireless power module 828, a wireless transceiver 826, an optical sensor 822, and a laser 820. The control circuitry 830 may include circuitry such as an ASIC, FPGA, or processor. The rotation sensor 824 may include a microelectromechanical system (MEMS) gyroscope for detecting rotation in one or more planes of rotation. Other types of rotation sensors are also possible, such as precision unit integrated (PCI) gyroscopes or fiber optic and ring laser gyroscopes.

[0094] The wireless power module 828 can draw power from the base unit 852 and distribute it throughout the spin unit 801. The wireless power module 828 may include a rechargeable battery. The laser 820 can be configured to emit laser light into the environment surrounding the spin unit 801. The optical sensor 822 can receive reflections of the laser light to create image data and provide the image data to the base unit 852 via the wireless transceiver 826.

[0095] The control circuit 830 can be configured to receive a command from the processor module 867 via the wireless transceiver 826 to start the laser 820. Prior to starting the laser 820, the control circuit 830 can be configured to check the rotational speed of the spin unit. The control circuit 830 can determine, based on the output of the rotation sensor 824, whether the rotational speed of the spin unit 801 is greater than or equal to a minimum rotational speed threshold. The minimum rotational speed threshold can be based on the power output rating of the laser. In an embodiment, the minimum rotational speed threshold is sufficient to cause the spin unit 801 to spin the laser 820 such that a predetermined eye safety power output criterion (such as the power requirements for a Class I laser device) is satisfied during the time that the spin unit 801 is spinning and the laser 820 is started. In an embodiment, the minimum rotational speed threshold is at least 600 RPM (revolutions per minute). In another embodiment, the minimum rotational speed threshold is set to 1200 RPM. Different threshold RPM values are also possible. In addition, different units for expressing rotational speed are possible, such as radians per minute, etc. The control circuit 830 can store the minimum rotational speed threshold in a non-volatile memory within or connected to the control circuit 830. In an embodiment, the minimum rotational speed threshold is permanently encoded in the logic circuit of the control circuit 830 such that it cannot be changed or overridden by the base unit 852 or other external sources.

[0096] If the rotational speed is sufficient, the control circuit 830 can start the laser 820 to produce a laser output in response to the command. For example, the starting can be based on a determination that the rotational speed of the spin unit 801 is greater than or equal to the minimum rotational speed threshold. Starting the laser 820 to produce a laser output can include powering the laser 820, providing appropriate start-up control input signals, or both. The control circuit 830 can be configured to obtain sensor measurements from the rotation sensor 824 during the time that the laser 820 is started. Using at least one of the sensor measurements, the control circuit 830 can be configured to suspend operation of the laser 820 based on a determination that the rotational speed of the spin unit 801 device is less than the minimum rotational speed threshold. The control circuit 830 can continue to sample during the time that the laser operation is suspended, and resume laser operation once the rotational speed is equal to or greater than the minimum rotational speed threshold.

[0097] The control circuit 830 can be configured to provide status information to the base unit 852 via the transceiver 826. The status information can include whether the laser 820 has been started, the rotational speed, whether the laser start command was successful, whether the laser operation was suspended due to insufficient rotational speed, etc. Other and different types of status information can be provided. In embodiments, multiple rotational sensors 824 can be used, and the control circuit 830 can use a voting mechanism or an averaging mechanism based on multiple data points from the individual sensors to determine whether there is sufficient rotational speed. In embodiments, multiple types of inertial measurement unit (IMU) sensors can be used to determine the rotational speed. In embodiments, the control circuit 830 can make sensor data adjustments to compensate for drift.

[0098] In embodiments, the control circuit can be configured to: receive a command to start the laser; in response to receiving the command, compare an output of the rotational sensor to a minimum rotational speed, and start the laser based on a result of the comparison. Comparing the output of the rotational sensor to the minimum rotational speed can include determining a measured rotational speed based on the output of the rotational sensor, and comparing the measured rotational speed to the minimum rotational speed. The comparison can include determining whether the measured rotational speed is greater than or equal to the minimum rotational speed threshold.

[0099] Figure 11 Another example of an architecture of a LiDAR spin unit 1101 is shown. In this example, some LiDAR components such as optical sensors are omitted for simplicity. The LiDAR spin unit 1101 includes a laser 1105, an FPGA 1110, a rotational sensor 1125, and a power and firing control circuit 1115. The FPGA 1110 includes control logic 1135 coupled with a switch 1130 that is located between the power and firing control circuit 1115 and the laser 1105. In this example, the switch 1130 is included as part of the FPGA 1110, however, the switch 1130 can be located outside of the FPGA 1110. Based on rotational speed measurements from the rotational sensor 1125, the control logic 1135 can cause the switch 1130 to transition to an on state, which enables the circuit between the power and firing control circuit 1115 and the laser 1105, and in turn, causes the laser 1105 to produce a laser output.

[0100] Figure 12 A flowchart showing an example of a process 1201 for performing safety checks before starting a laser of a LiDAR is shown. The process 1201 can be performed by a processor module such as the processor module 867 of the base unit of the LiDAR and the spin unit of the LiDAR. Figure 9 Figure 10 ​The control circuit, such as 830, is used for control. In 1205, the processor module in the base unit transmits commands to activate the laser of the LiDAR's spin unit. Wireless communication between the spin unit and the base unit is possible.

[0101] At 1210, the control circuitry of the spin unit receives a command to activate the laser. At 1215, the control circuitry obtains a measurement from a sensor used to detect the rotation of the spin unit in the plane of rotation. Obtaining the measurement result may include receiving sensor events from the sensor, polling the sensor for sensor data, or monitoring the voltage on the line coupled to the sensor. Other techniques for obtaining sensor measurement results are also possible.

[0102] At 1220, the control circuit determines, based on the measurement result, whether the rotational speed of the spin unit is greater than or equal to a minimum rotational speed threshold. In an embodiment, the control circuit may perform one or more calculations to convert the sensor measurement result (e.g., angular rate) into a rotational speed measurement result (e.g., RPM). If the control circuit determines that the rotational speed of the spin unit is less than the minimum rotational speed, then at 1225, the control circuit may send an error status to the base unit. In an embodiment, the control circuit is configured to provide status information to the base unit when the spin unit is not allowed to perform the command based on the determination that the rotational speed of the spin unit is less than the minimum rotational speed threshold. The status information may include a status value indicating that the spin unit is not spinning or is spinning at an excessively slow speed.

[0103] Otherwise, if the spin unit's rotational speed is greater than or equal to the minimum rotational speed, then at 1230, the control circuit responds to the command to start the laser to generate output. During startup, the control circuit can perform additional checks on the rotational speed. The control circuit can periodically (e.g., every 0.1 seconds, 0.5 seconds, 1 second, or 2 seconds) obtain sensor measurements. At 1235, during laser startup, the control circuit can obtain one or more sensor measurements from the sensors. At 1220, the rotational speed is checked again, and if the rotational speed is greater than or equal to the minimum rotational speed threshold, the control circuit can maintain laser startup at 1230. Otherwise, at 1225, the control circuit can send an error status and deactivate the laser. In one embodiment, the control circuit is configured to pause laser operation based on a single measurement indicating a rotational speed less than a minimum value. In another embodiment, the control circuit is configured to pause laser operation based on a moving average of the last N samples indicating an average rotational speed less than a minimum value, where N is an integer greater than 1.

[0104] In the foregoing description, embodiments of the application have been described with reference to numerous specific details that can vary with implementation. Accordingly, the specification and drawings are to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the application, and what is intended by the applicants to be the scope of the application, is the literal and equivalent scope of the claims issued from this application in their specific form as published by the issuing Patent Office, including any subsequent corrections. Any definitions of terms here in this detailed description are expressly incorporated by reference from the specific and extensive definitions of terms in the published specification of the present application. In addition, where the foregoing specification has used the term "including" to refer to the inclusion of one or more elements, it is intended that the term "including" be interpreted as meaning "including, but not limited to." Moreover, where the foregoing specification has used the term "the term" to refer to the inclusion of one or more elements, it is intended that the term "the term" be interpreted as meaning "the term, but not limited to."

Claims

1. A device comprising: a laser, wherein the device is configured to cause the laser to rotate in a rotational plane; a sensor to detect rotation of the device in the rotational plane; and control circuitry configured to: receive a command to activate the laser, determine, based on output of the sensor, whether a rotational speed of the device is greater than or equal to a minimum rotational speed threshold, and based on a determination that the rotational speed of the device is greater than or equal to the minimum rotational speed threshold, activate the laser to produce a laser output in response to the command, wherein the device is coupled with a base unit configured to cause the device to rotate, wherein the control circuitry is configured to receive the command from the base unit, wherein the control circuitry is configured to obtain sensor measurements from the sensor during the laser is activated, and based on a determination that the rotational speed of the device is less than the minimum rotational speed threshold using at least one of the sensor measurements, suspend operation of the laser, and based on a determination that the rotational speed of the device is greater than or equal to the minimum rotational speed threshold, maintain operation of the laser, wherein the control circuitry is configured to provide status information to the base unit based on a determination that the rotational speed of the device is less than the minimum rotational speed threshold without allowing the device to act on the command during the laser is not activated.

2. The apparatus of claim 1, wherein, the minimum rotational speed threshold is sufficient for the device to cause the laser to rotate such that a predetermined eye safety power output criterion is satisfied during the device is rotating and the laser is activated.

3. The apparatus of claim 1 or 2, wherein, the minimum rotational speed threshold is at least 600 rotations per minute.

4. The apparatus of claim 1 or 2, wherein, the sensor comprises a microelectromechanical system (MEMS) gyroscope.

5. A system comprising: a spin unit comprising a laser, the spin unit configured to cause the laser to rotate in a rotational plane; and a base unit coupled with the spin unit, the base unit comprising a motor to cause the spin unit to rotate in the rotational plane and a processor configured to send a command to activate the laser, wherein the spin unit further comprises: a sensor to detect rotation of the spin unit in the rotational plane; and control circuitry configured to: receive the command to activate the laser, determine, based on output of the sensor, whether a rotational speed of the spin unit is greater than or equal to a minimum rotational speed threshold, and based on a determination that the rotational speed of the spin unit is greater than or equal to the minimum rotational speed threshold, activate the laser to produce a laser output in response to the command, wherein the control circuitry is configured to obtain sensor measurements from the sensor during the laser is activated, and based on a determination that the rotational speed of the spin unit is less than the minimum rotational speed threshold using at least one of the sensor measurements, suspend operation of the laser, and based on a determination that the rotational speed of the spin unit is greater than or equal to the minimum rotational speed threshold, maintain operation of the laser, wherein the control circuit is configured to provide status information to the base unit in the event that the spin unit is not allowed to proceed with the command based on a determination that a rotational speed of the spin unit is less than the minimum rotational speed threshold during the laser is not activated.

6. The system of claim 5, wherein, the minimum rotational speed threshold is sufficient to cause the spin unit to rotate the laser such that a predetermined eye safety power output criterion is satisfied during the spin unit is rotating and the laser is activated.

7. The system of claim 5 or 6, wherein, the minimum rotational speed threshold is at least 600 rotations per minute.

8. The system of claim 5 or 6, wherein, the sensor comprises a micro-electro-mechanical system (MEMS) gyroscope.

9. A method comprising: transmitting, from a base unit of a LIDAR system, a command to activate a laser of a spin unit of the LIDAR system, the spin unit configured to rotate the laser in a rotation plane; at the spin unit, receiving the command to activate the laser; at the spin unit, obtaining measurements from a sensor configured to detect rotation of the spin unit in the rotation plane; at the spin unit, determining, based on the measurements, whether a rotational speed of the spin unit is greater than or equal to a minimum rotational speed threshold; and at the spin unit, activating the laser to produce a laser output in response to the command based on a determination that the rotational speed of the spin unit is greater than or equal to the minimum rotational speed threshold, the method further comprising: at the spin unit, obtaining sensor measurements from the sensor during the laser is activated; and at the spin unit, suspending operation of the laser based on a determination that the rotational speed of the spin unit is less than the minimum rotational speed threshold using at least one of the sensor measurements, and maintaining operation of the laser based on a determination that the rotational speed of the spin unit is greater than or equal to the minimum rotational speed threshold, the method further comprising: providing, by the spin unit, status information to the base unit in the event that the spin unit is not allowed to proceed with the command based on a determination that a rotational speed of the spin unit is less than the minimum rotational speed threshold during the laser is not activated.

10. The method of claim 9, wherein, the minimum rotational speed threshold is sufficient to cause the spin unit to rotate the laser such that a predetermined eye safety power output criterion is satisfied during the spin unit is rotating and the laser is activated.

11. The method of claim 9 or 10, wherein, the minimum rotational speed threshold is at least 600 rotations per minute.

12. The method of claim 9 or 10, wherein, the sensor comprises a micro-electro-mechanical system (MEMS) gyroscope.

13. A non-transitory computer-readable storage medium comprising at least one program for execution by at least one processor of an apparatus, the at least one program comprising instructions, which, when executed by the at least one processor, cause the apparatus to perform the method according to any one of claims 9 to 12.

14. A computer program product comprising at least one program for execution by at least one processor of an apparatus, the at least one program comprising instructions, which, when executed by the at least one processor, cause the apparatus to perform the method according to any one of claims 9 to 12.

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