Patent ID: 12216231

DETAILED DESCRIPTION

Exemplary implementations are described herein. It should be understood that the word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation or feature described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations or features. In the figures, similar symbols typically identify similar components, unless context dictates otherwise. The example implementations described herein are not meant to be limiting. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations.

I. Overview

In many applications, it can be beneficially to couple an apparatus to a base structure via a rotary link that enables the apparatus to rotate relative to the base structure (e.g., about an axis of rotation). In such applications, it may be desirable to wirelessly transmit data to or from the apparatus via the rotary link and/or to wirelessly transmit power to the apparatus via the rotary link.

The base structure could be, for example, a mobile structure, such as a vehicle or robot, or the base structure could be a stationary structure, such as a building. The apparatus could be, for example, a rotating portion of a light detection and ranging (LIDAR) device, a camera, a radar unit, an inertial measurement unit (IMU), or other type of sensing device. The apparatus may include one or more electronic components that operate using electrical power and that generate and/or receive data. Such electrical components may include without limitation one or more sensors (e.g., light detectors, image sensors, motion sensors, etc.), transmitters (e.g., radio transmitters, light transmitters, ultrasonic transmitters, etc.), controllers (e.g., microcontrollers, processors, floating point gate arrays (FPGAs), application specific integrated circuits (ASICs), etc.), motors, or other components that operate using electrical power.

In some implementations, the rotating apparatus may include a source of electrical power, such as a battery, that can power the one or more electrical components of the apparatus. In other implementations, however, it may be beneficial to power the one or more electrical components using a source of electrical power in the base structure. For example, the base structure could be a vehicle that includes a battery. In that case, it may be beneficially to convey electrical power from the vehicle's battery to the rotating apparatus via the rotary link.

In some implementations, it may be beneficial to transmit data generated by the rotating apparatus to a computing device in the base structure via the rotary link. For example, the rotating apparatus may generate LIDAR data, image data, radar data, motion data, or other sensor data that may be analyzed by the computing device. In implementations in which the base structure is a vehicle or robot, the computing device may use such data to detect objects in the environment, navigate through the environment, or otherwise control operations of the vehicle or robot (e.g., in an autonomous mode). In addition, it may be beneficial for the computing device to transmit data (e.g., instructions, configuration parameters, etc.) to the rotating apparatus via the rotary link.

In example embodiments, the rotary link includes a first platform that is coupled to the base structure and a second platform to which the apparatus is coupled. The second platform is spaced apart from the first platform by a gap (e.g., an air gap) and is configured to rotate relative to the first platform about the rotary link's axis of rotation. Thus, transmitting data to or from the apparatus via the rotary link may involve wirelessly transmitting data via the gap and transmitting power from the base structure to the apparatus via the rotary link may involve wirelessly transmitting power via the gap.

To wirelessly transmit power via the gap, the rotary link may include a wireless power transformer that includes a primary winding in the first platform and a secondary winding in the second platform. The primary winding is inductively coupled to the secondary winding across the gap such that an alternating magnetic field is able to wirelessly transmit power through the gap. In example embodiments, the primary and secondary windings are toroidal coils that are concentrically arranged about the rotary link's axis of rotation.

To provide the alternating magnetic field in the wireless power transformer, a DC power source (e.g., a battery) in the base structure can drive an oscillator (e.g., a switching circuit) to generate an AC signal that is applied to the primary winding (e.g., via an LLC resonant circuit). The resulting AC signal at the secondary winding may be rectified and filtered to provide a DC voltage that can power the electrical components in the rotating apparatus.

To wirelessly transmit data via the gap, the rotary link may include a wireless data transformer that includes a first conductive structure in the first platform and a second conductive structure in the second platform. The first and second conductive structures are inductively coupled together across the gap such that an alternating magnetic field is able to wirelessly transmit data through the gap. In example embodiments, the first and second conductive structures are conductive loops (either single turn conductive loops or multi-turn conductive loops) that are concentrically arranged about the rotary link's axis of rotation.

To provide the alternating magnetic field in the wireless data transformer, a radio frequency (RF) signal may be modulated with the data to be wireless transmitted via the gap (e.g., data transmitted to or from the rotating apparatus) to provide a data-modulated RF signal. The data-modulated RF signal may be applied to the first conductive loop and received at the second conductive loop, or vice versa.

Such RF-based wireless data transmission may be in accordance with a particular set of data communication specifications, such as the G.hn specifications. The G.hn specifications comprise a series of recommendations published by the International Telecommunications Union (ITU). G.hn was originally developed for home networking applications over power lines. However, as presently specified, G.hn allows for data communications over various types of physical media, including power lines, twisted-pair telephone wiring, coaxial cable, and optical fiber.

G.hn specifies a physical layer that is based on orthogonal frequency-division multiplexing (OFDM). In the OFDM approach, data is transmitted over a plurality of sub-carriers, with each sub-carrier being modulated with a portion of the data using, for example, quadrature amplitude modulation (QAM). In example embodiments, the sub-carriers have frequencies that are greater than 1 MHz and less than 1 GHz, and the spacing between sub-carriers is about 195 kHz. For example, the plurality of sub-carriers may occupy a range of frequencies, such as 2-50 MHz or 2-200 MHz. The data can also be encoded with forward error correction codes, such as low-density parity-check (LDPC) codes, before being modulated onto the sub-carriers. The combination of OFDM and error correction codes enables G.hn to support high data rates (e.g., over 100 Mbits/second or over 1 Gbits/second) in noisy environments.

G.hn also specifies a media access control (MAC) layer that schedules channel access using time divisional multiple access (TDMA). The G.hn MAC layer can allocate time slots for contention-free channel access. The G.hn MAC layer also supports time slots for contention-based channel access.

Chipsets that support data transmission and reception in accordance with G.hn specifications (including the physical layer and the MAC layer) are commercially available. Such chipsets can be used to implement G.hn-based communication interfaces for transmitting and receiving data via a wireless data transformer in a rotary link.

In an example embodiment, a first G.hn-based communication interface is connected to the first conductive structure of the wireless data transformer and a second G.hn-based communication interface is connected to the second conductive structure of the wireless data transformer. A data source in the rotating apparatus may send data (e.g., LIDAR data, image data, radar data, or motion data) to the second G.hn-based communication interface for transmission to a computing device or other destination connected to the first G.hn-based communication interface. The second G.hn-based communication interface may encode the data with error correction codes and modulate the encoded data onto a plurality of sub-carriers to provide a data-modulated RF signal that is transmitted over the gap from the second conductive structure to the first conductive structure. The first G.hn-based communication interface receives the data-modulated RF signal and performs demodulation and decoding steps to recover the data from the data source. The computing device or other destination may then receive the recovered data from the first G.hn-based communication interface. Electronic components in the rotating apparatus may receive data transmitted from the first G.hn-based communication interface to the second G.hn-based communication interface (via the wireless data transformer) in a similar manner.

Although example embodiments are described herein using G.hn specifications to transmit and receive data via the wireless data transformer, it is to be understood that other data communication specifications, standards, or protocols may be used.

In example embodiments, the rotary link includes both a wireless power transformer and a wireless data transformer. For example, the first platform may include a primary winding and a first conductive loop that at least partially surrounds the primary winding, and the second platform may include a secondary winding and a second conductive loop that at least partially surrounds the secondary winding. Alternatively, the primary and secondary windings may at least partially surround the first and second conductive loops.

With the rotary link including both a wireless power transformer and a wireless data transformer, some amount of interference is possible. For example, the alternating electric and/or magnetic fields used to transmit power through the wireless power transformer may create an interfering signal in the wireless data transformer, or vice versa. To reduce such interference, the wireless power transformer may operate at a frequency that is well outside of the bandwidth of the wireless data transformer. For example, the AC signal that transmits power in the wireless power transformer may have a frequency of about 75 kHz, whereas the RF signal that transmits data in the wireless data transformer may use only much higher frequencies (e.g., frequencies greater than 2 MHz).

In another approach for reducing interference, the first platform may include a first isolation ring between the first conductive loop and the primary winding, and the second platform may include a second isolation ring between the second conductive loop and the secondary winding. The first and second isolation rings include a high magnetic permeability material (e.g., ferrite) to provide some degree of isolation between the alternating and magnetic fields in the wireless power transformer and the alternating magnetic fields in the wireless data transformer.

II. Example Data Communication Systems

FIG.1is a block diagram of an example data communication system100that includes a sensing device102and a vehicle104. The sensing device102could be, for example, a LIDAR device, a camera, a radar unit, or an IMU. The vehicle104could be, for example, an automobile or other land-based vehicle, an airplane, a boat, or other type of vehicle. In this example, sensing device102includes a stationary portion106, which is physically attached to the vehicle104by means of a mounting structure108, and a rotating portion110that is able to rotate relative to the stationary portion106about an axis of rotation. The rotating portion110is spaced apart from the stationary portion106by an air gap112.

Sensing device102includes a wireless data transformer114that enables data to be communicated through the air gap112. The data communication through the air gap112could be either unidirectional (e.g., from the rotating portion110to the stationary portion106) or bidirectional. To achieve this data communication, wireless data transformer114includes a first data communication component116in the stationary portion106and a second data communication component118in the rotating portion110. Data communication components116and118can include any structures that can communicate data via the air gap112. In example embodiments, data communication components116and118include conductive structures that are inductively together across the air gap (e.g., data communication components116and118may each include a conductive loop that is concentric with the axis of rotation of the rotating portion). Alternatively, data communication components116and118may include structures that are communicatively coupled across the air gap112in other ways, such as capacitively coupled, electromagnetically coupled (e.g., data communication components116and118may include respective antennas), or optically coupled.

In the example illustrated inFIG.1, the rotating portion110includes one or more components that generate data that is transmitted through the air gap112. As shown, rotating portion110includes one or more sensor(s)120and an application processor122. Sensor(s)120may include one or more light detectors, image sensors, radio receivers, accelerometers, gyroscopes, magnetometers, or other types, as well as associated electronics (e.g., analog-to-digital converters), depending on the nature of sensing device102. Sensors(s) may also include motor encoders that generate data indicative of a rotor position within a motor. Thus, sensor(s)120may generate data indicative of the environment of sensing device102, data indicative of motion or pose of the sensing device102or other type of type data. The application processor122may be a microprocessor, microcontroller, FPGA, ASIC, or other device that controls the functioning of sensing device102. The application processor122may process the data generated by sensor(s)120.

In the example illustrated inFIG.1, the destination for the data generated by sensor(s)120is a computing device130located in the vehicle104. The computing device130may use the data generated by sensor(s)120to detect objects in the environment of the vehicle104, to determine the pose, location, or speed of the vehicle104, or to determine other aspects of the vehicle104or its environment. As shown, computing device130includes one or more processor(s)132and data storage134. The data storage134may include volatile memory, non-volatile memory, or other computer-readable media and may store program instructions that are executable by the processor(s)132to control the functioning of computer device130.

In example embodiments, the data generated by the sensor(s)120is transmitted to the computing device130in accordance with G.hn specifications. To support the G.hn communications, the rotating portion110includes a G.hn communication interface140, and the vehicle104includes a G.hn communication interface142. The G.hn communication interfaces140and142may perform G.hn physical layer functions as well as G.hn MAC layer functions. On the transmit side, the G.hn physical layer functions may include encoding data with error correction codes and modulating the encoded data onto a plurality of sub-carriers to provide a data-modulated RF signal. On the receive side, the G.hn physical layer functions may include demodulating the data-modulated RF signal to recover the encoded data and decoding the encoded data to recover the original data. The G.hn MAC layer functions may include controlling access to the communication medium used to transmit and receive data. The G.hn communication interfaces140and142may perform other functions as well.

The G.hn communication interface140may be communicatively coupled to the sensor(s)120via the application processor122. Thus, the G.hn communication interface140may receive data generated by sensor(s)120that has been processed by application processor122. Alternatively, the G.hn communication interface140may receive the data from the sensor(s)120directly.

The G.hn communication interface140is also communicatively coupled to the data communication component118of the wireless data transformer114. In this way, data communication component118receives the output of G.hn communication140, so that the data generated by sensor(s)120is transmitted over the G.hn physical layer. Specifically, the G.hn communication interface140may encode the data with error correction codes and modulate a plurality of sub-carriers with the encoded data to provide a data-modulated RF signal that is transmitted to the wireless data transformer114. The data-modulated RF signal is then transmitted through the air gap112due to the inductive coupling between the data communication components116and118.

In example embodiments, the G.hn communication interface142is communicatively coupled to the data communication component116of the wireless data transformer114by a wired connection. As shown inFIG.1, a data communication cable144is connected to a connector146on the stationary portion106and to a connector148on the vehicle104. The data communication cable144could be, for example, a twisted-pair wire in a shielded cable or a coaxial cable. The connector146is connected to the data communication component116, and the connector148is connected to the G.hn communication interface142. Additionally, G.hn communication interface142is communicatively coupled to the computing device130. In this way, the G.hn communication interface142receives the data-modulated RF signal via the data communication cable144, demodulates the data-modulated RF signal to recover the encoded data, decodes the encoded data to recover the data generated by the sensor(s)120, and transmits the data to the computing device130.

The G.hn communication interfaces140and142may also transmit data from the computing device130to the application processor122and/or other components in the rotating portion110(e.g., using time-division duplexing). The data transmitted from the computing device130may include, for example, instructions to control the functioning of application processor122, calibration data, configuration parameters, or some other type of data.

The process of transmitting data from the computing device130to the application processor122may be similar to the process of transmitting data to the computing device130, but in the other direction. Thus, G.hn communication interface142receives the data from computing device130and performs transmit-side G.hn physical layer functions (encoding, modulation) to provide a data-modulated RF signal that is transmitted to the data communication component116of the wireless data transformer114. The data-modulated RF signal is transmitted through the air gap112due to the inductive coupling between data communication components116and118and is received by G.hn communication interface140. The G.hn communication interface140performs receive-side G.hn physical layer functions (demodulation, decoding) to recover the data from computing device130and transmits the data to the application processor122.

G.hn also supports point-to-multipoint (PTMP) data communications.FIG.2illustrates an example PTMP data communication system200. For purposes of illustration, system200includes the computing device130and G.hn communication interface142shown inFIG.1. In system200, however, the computing device130is in communication with a plurality of sensing devices, exemplified inFIG.2by sensing devices102a-102d, via the G.hn communication interface142and a passive splitter202. In an example embodiment, computing device130, G.hn communication interface142, and passive splitter202splitter are located within the vehicle104, whereas sensing devices102a-102dare mounted on exterior portions of the vehicle104. The communications between the passive splitter202and the sensing devices102a-102dcould be via wired connections. As shown inFIG.2, sensing devices102a-102dare communicatively coupled to passive splitter202via respective data communication cables212a-212d.

The sensing devices102a-102dcould be similar to sensing device102described above forFIG.1. Thus, sensing devices102a-102dcould include, without limitation, LIDAR devices, cameras, radar units, or IMUs. To support G.hn communications, sensing devices102a-102dmay each include a respective G.hn communication interface (not shown). In addition, one or more of the sensing devices102a-102dmay include a rotary link with a wireless data transformer similar to wireless data transformer114shown inFIG.1.

The PTMP communications supported by system200could involve any of sensing devices102a-102dtransmitting data to computing device130and/or computing device130transmitting data to any of sensing devices102a-102d. AlthoughFIG.2shows four sensing devices102a-102dfor purposes of illustration, it is to be understood that a PTMP data communication system could support G.hn data communications between computing device130and any number of sensing devices.

III. Example Wireless Power Transmission System

In addition to being able to communicate data via the air gap112, sensing device102may be configured to transmit power via the air gap112so as to power various electrical components in the rotating portion110.FIG.3illustrates an example wireless power transmission system300. In example embodiments, system300may include the data communication components of sensing device102and vehicle104illustrated inFIG.1(e.g., wireless data transformer114, G.hn communication interfaces140and142). However, for purposes of illustration,FIG.3focuses on the components of sensing device102and vehicle104that are relevant to power transmission.

In the example shown inFIG.3, the sensing device102is powered by a battery302(a DC voltage source) in the vehicle104. The battery302may power various components in the vehicle as well, such as computing device130. To convey electrical power from the battery302to the sensing device102, the battery302may be electrically connected to a connector304on the vehicle104, and a power cable306may be electrically connected to the connector304on the vehicle104and a corresponding connector308on the stationary portion106of the sensing device102.

The electrical power from the battery302may be used to power various electrical components in the sensing device102, including electrical components310in the rotating portion110. The electrical components310may include the sensor(s)120, application processor122, and G.hn communication interface140shown inFIG.1, as well as other electrical components, depending on the type of sensing device102.

For example, in embodiments in which the sensing device102is a LIDAR device, the electrical components310may include one or more light emitter(s)312, one or more light detector(s)314, and one or more motor(s)316. The light emitter(s)312may emit light pulses into an environment of the LIDAR device. The light detector(s)314may detect returning light pulses corresponding to portions of emitted light pulses that have reflected from objects in the environment. The motor(s)316may rotate or otherwise move one or more elements of the LIDAR device. For example, the motor(s)316may include a motor that rotates the rotating portion110relative to the stationary portion. Alternatively or additionally, the motor(s)316may include a motor that rotates a mirror that reflects light pulses emitted by the emitter(s)312into the environment and that reflects returning light pulses from the environment toward the light detector(s)314.

In order to transmit power via the air gap112, the sensing device102may include a wireless power transformer320. The wireless power transformer320includes a primary winding322in the stationary portion106and a secondary winding324in the rotating portion110. The primary and secondary windings322and324are inductively coupled together across the air gap112, such that an AC signal can be transmitted from the primary winding322to the secondary winding324via the air gap112.

The stationary portion106may include a power conversion circuit that converts the DC voltage from the battery302into an AC signal that can be transmitted by inductive coupling across the air gap112. In example embodiments, the power conversion circuit includes an oscillator330(e.g., a switching circuit) that is electrically connected to the connector308(e.g., via a pre-regulator or other circuitry) and an LLC resonant circuit332(e.g., an LLC tank circuit) that is electrically connected to the oscillator330and to the primary winding322. In operation, the oscillator330receives the DC voltage from the battery302and generates a waveform (e.g., a square-wave signal) that has a fundamental frequency and higher frequency components (e.g., harmonics). The shape of the waveform and the fundamental frequency can be selected in order to minimize interference between the frequency components of the waveform and the sub-carrier frequencies used for the G.hn data communication.

The waveform generated by the oscillator330(e.g., a square-wave signal) is applied to the LLC resonant circuit332to generate a sinusoidal signal at the fundamental frequency. The sinusoidal signal is applied to the primary winding322and, in response, the secondary winding324develops a corresponding sinusoidal signal due to the inductive coupling between the primary winding322and the secondary winding324. In this way, an AC signal is transmitted to the rotating portion110through the air gap112.

In the rotating portion110, a rectifier/filter circuit334is electrically connected to the secondary winding324and to the electrical components310. The rectifier/filter334rectifies the AC signal from the secondary winding324and filters the rectified signal to provide a DC voltage that powers the electrical components310.

IV. Example Rotary Link Structures

FIG.4is a cross-sectional view of an example rotary link400. In this example, rotary link400includes a first platform402and a second platform404that is spaced apart from the first platform by a gap406. The second platform404is configured to rotate relative to the first platform402about an axis of rotation408. With reference toFIGS.1and3, the first platform402could be part of the stationary portion106, the second platform404could be part of the rotating portion110, and the gap406may correspond to the air gap112.

FIG.5is a view of the first platform402from the gap406. The second platform404may be similarly configured.

As shown inFIGS.4and5, the first and second platforms402and404are cylindrical, and the gap406between the first and second platforms402and404is uniform. It is to be understood, however, that the first and second platforms402and404could have any shape. Further, the gap406between the first and second platforms402and404could be non-uniform. For example, the size of the gap406may be different at different radial distances from the axis of rotation408, based on the shapes of the first and second platforms402and404. In addition, different portions of the gap406may have different axial positions, based on the shapes of the first and second platforms402and404.

The first and second platforms402and404could be composed of any suitable materials, such as metallic or plastic materials. In example embodiments, the gap406is an air gap. However, the gap406could also include an oil or other fluid material. In example embodiments, the size of the gap406is on the order of 1 millimeter (e.g., between 0.5 and 1.5 millimeters). However, other sizes of the gap406are possible and are contemplated herein.

In the example illustrated in Figured4and5, the first and second platforms402and404include structures to implement both a wireless data transformer (e.g., similar to wireless data transformer114) and a wireless power transformer (e.g., similar to wireless power transformer320) in the rotary link400. It is to be understood, however, that a rotary link could alternatively include a wireless data transformer without a wireless power transformer, or a wireless power transformer without a wireless data transformer.

To implement a wireless data transformer in rotary link400, the first platform402includes a printed circuit board (PCB)410that has a pattern of conductive traces formed thereon, and the second platform404includes a PCB412that has a similar pattern of conductive traces formed thereon. As shown inFIG.5, the conductive traces on PCB410from a conductive loop414that extends between a contact416and a contact418(two turns around the axis of rotation408). The conductive loop414can be electrically connected to other electrical components (not shown) via contacts416and418. The conductive traces on PCB412could be similar to the conductive loop414on PCB410and may be electrically connected to other electrical components (not shown) via electrical contacts. In example embodiments, the conductive loops on the PCBs410and412could be electrically connected to respective G.hn communication interfaces (e.g., as described above forFIG.1).

As shown inFIG.5, the conductive loop414is a two-turn loop. It is to be understood, however, that conductive loop414could include a greater or fewer number of turns. Further, whileFIG.5illustrates an example in which the conductive traces on PCB410are in the form of a loop, it is to be understood that the conductive traces could be configured in other ways.

In example embodiments, the PCBs410and412are positioned such that their respective conductive traces directly face each other across the gap406, so as to maximize the inductive coupling between the conductive traces. With this inductive coupling, a data-modulated RF signal applied to the conductive traces on PCB412can be transmitted via the gap406to the conductive traces on PCB410. Similarly, a data-modulated RF signal applied to the conductive traces on PCB410can be transmitted via the gap406to the conductive traces on PCB412. In this way, the conductive traces on PCBs410and412can provide a wireless data transformer in rotary link400.

To implement a wireless power transformer in rotary link400, the first platform402includes a primary winding420and the second platform404includes a secondary winding422. In example embodiments, the primary and secondary windings420and422are toroidal coils that are disposed within ferrite cores424and426, respectively.

As shown inFIG.5, the primary winding420and ferrite core424are symmetrically arranged about the axis of rotation408at a particular radial distance. The secondary winding422and ferrite core426may be similarly arranged at the same radial distance from the axis of rotation. With this configuration, primary and secondary windings420and424directly face either across the gap406, so as to maximize the inductive coupling between them. With this inductive coupling, an AC signal applied to the primary winding420is transmitted to the secondary winding422via the gap406. The primary and secondary windings420and422may include respective conductive leads (not shown) to electrically connect the primary and secondary windings420and422to other electrical components.

The ferrite cores424and426confine magnetic flux from the primary and secondary windings420and422, respectively. This confinement of magnetic flux can beneficially increase the inductive coupling between the primary and secondary windings420and422. The confinement of magnetic flux provided by the ferrite cores424and426can also reduce inductive coupling between the primary and secondary windings420and422and the conductive structures in PCBs410and412, respectively. This, in turn, can reduce interference between the signals transmitted through the wireless power transformer and the data-modulated RF signals transmitted through the wireless data transformer.

In the example illustrated inFIGS.4and5, the conductive loop414disposed on PCB410surrounds the primary winding420in the first platform402, and the conductive loop (not shown) disposed on PCB412surrounds the secondary winding424in the second platform404. In other examples, however, the primary and secondary windings of the wireless power transformer may surround the conductive loops (or other conductive structures) of the wireless data transformer. In addition, whileFIG.4shows the primary winding420axially aligned with the PCB410and the secondary winding422axially aligned with the PCB412, it is to be understood that the primary and secondary windings of the wireless power transformer could have different axial positions than the conductive structures of the wireless data transformer.

V. Example Lidar Device

FIG.6illustrates an example LIDAR device600in which power and data are transmitted over a rotary link. In this example, LIDAR device600includes a stationary portion602, which could be mounted to a vehicle or other base structure, and a rotating portion604. The rotating portion604is configured to rotate about an axis of rotation606. In example embodiments, the rate of rotation could be between 3 Hz and 60 Hz, though other rotation rates are possible as well.

The stationary portion602and rotating portion604include respective housings608and610. The housing610of the rotating portion602includes an optical window612. Within the housing610, the rotating portion includes various components to transmit light pulses into an environment of the LIDAR device600, via optical window612, and to receive returning light pulses from the environment, via optical window612. The returning light pulses correspond to transmitted light pulses that have been reflected by objects in the environment, exemplified inFIG.6by object614.

The light pulses could have any wavelength in the ultraviolet, visible, or infrared portions of the electromagnetic spectrum. In example embodiments, the light pulses have near-infrared wavelengths (e.g., wavelengths between 800 and 1600 nanometers (nm), such as 905 nm). The optical window612is composed of a material that is transparent to the wavelengths of the transmitted light pulses. For example, the optical window612could be a polymeric material (e.g., polycarbonate, acrylic, etc.), glass, quartz, or sapphire.

In this example, the rotating portion604includes an optical cavity620that includes one or more light emitters622and one or more light detectors624. The one or more light emitters622could include, for example, laser diodes, laser diode bars, light emitting diodes (LEDs) or other types of light sources. The one or more light detectors624may include, for example, avalanche photodiodes (APDs), single-photon avalanche diodes (SPADs), silicon photomultipliers (SiPMs), or other types of light detectors.

The one or more light emitters622are configured to emit light pulses that propagate along a transmit path626. The one or more light detectors624are configured to detect returning light pulses that propagate along a receive path628. A mirror630deflects the emitted light pulses from the transmit path626toward the optical window612for transmission into the environment. In addition, returning light pulses from objects in the environment (e.g., object614) can enter the LIDAR device through the optical window612and can be deflected by the mirror630into the receive optical path628.

In example embodiments, the mirror630includes four reflective surfaces630a-630dthat are symmetrically arranged around a mirror shaft632. The mirror shaft632is driven by a mirror motor (not shown) that causes rotation of the mirror630about a mirror axis of rotation (e.g., the axis of the shaft632), which may be perpendicular to the axis of rotation606. With this rotation of mirror630, different reflective surfaces of the reflective surfaces630a-630dintersect the transmit and receive paths626and628at different times.FIG.6illustrates a point in time when reflective surface630cintersects the transmit and receive paths626and628. AlthoughFIG.6illustrates an example in which the mirror630includes four reflective surfaces. The mirror630could include a greater or fewer number of reflective surfaces.

The rotating portion604may rotate about the axis of rotation606at the same time that the mirror630rotates about the mirror axis of rotation. In the example illustrated inFIG.6, the rotation of the rotating portion602involves the rotation of an inner shaft640relative to an outer shaft642. The inner and outer shafts are concentrically arranged and rotationally coupled together by a bearing644. The inner shaft640is connected to a base plate646, which is connected to the housing610of the rotating portion640. The outer shaft642is connected to the housing608of the stationary portion602.

A motor650(indicated by dashed lines) causes rotation of the inner shaft640relative to the outer shaft642and, thus, rotation of the rotating portion604relative to the stationary portion602. The motor650includes a stator652that is supported by the base plate646. Current applied to the stator652(e.g., current flowing through a field winding in the stator652) generates a magnetic field that interacts with magnets654disposed on the outer shaft642(rotor) to cause rotation. Because the outer shaft642(rotor) is part of the stationary portion602(e.g., the outer shaft642is connected to the housing608of the stationary portion602) and the stator652is part of the rotating portion604(e.g., the stator652is supported by the base plate646, which is connected to the housing610of the rotating portion604). The resulting rotation is rotation of the rotating portion604relative to the stationary portion602.

The rotating portion604of the LIDAR device600may generate data that is transmitted into the stationary portion602via a wireless data transformer. Such data may include, for example, data indicative of returning light pulses detected by the one or more light detectors624(e.g., the times when returning light pulses are detected, the magnitudes of the returning light pulses, the shapes of the returning light pulses, etc.). Such data may further include data indicative of the position of mirror630about the mirror rotation axis (e.g., data from an encoder in the mirror motor) and data indicative of the position of the rotating portion604about the axis of rotation606(e.g., data from an encoder in motor650) as a function of time.

Electrical components of the rotating portion604may also be powered by electrical power that is transmitted from the stationary portion602via a wireless power transformer. Such electrical components may include, for example, motor650, the mirror motor, the one or more light emitters622, and the one or more light detectors624. Such electrical components may also include other electronics not shown inFIG.6. For example, the rotating portion604may include an application processor and a G.hn communication interface (e.g., as shown inFIG.2).

To implement a wireless data transformer and a wireless power transformer in LIDAR device600, the stationary portion602includes a first platform660mounted on the outer shaft642, and the rotating portion604includes a second platform662mounted on the base plate646. A first PCB664is disposed on the first platform660, and a second PCB666is disposed on the second platform662. The PCBs664and666are spaced apart by a gap and include respective conductive traces (e.g., respective conductive loops) that are inductively coupled together across the gap so as to form a wireless data transformer (e.g., as described above forFIG.4). A primary winding670and ferrite core672are disposed in the first platform660, and a secondary winding674and ferrite core676are disposed in the second platform662. The primary and secondary windings670and674are spaced apart by a gap and are inductively coupled together across the gap so as to form a wireless power transformer (e.g., as described above forFIG.4).

VI. Example Vehicles

FIGS.7A-7Eillustrate a vehicle700, according to an example embodiment. The vehicle700could be a semi- or fully-autonomous vehicle. WhileFIGS.7A-7Eillustrates vehicle700as being an automobile (e.g., a minivan), it will be understood that vehicle700could include another type of autonomous vehicle, robot, or drone that can navigate within its environment using sensors and other information about its environment.

The vehicle700may include one or more sensor systems702,704,706,708, and710. In example embodiments, sensor systems702,704,706,708, and710each include a respective LIDAR device. In addition, one or more of sensor systems702,704,706,708, and710could include radar devices, cameras, or other sensors.

The LIDAR devices of sensor systems702,704,706,708, and710may be configured to rotate about an axis (e.g., the z-axis shown inFIGS.7A-7E) so as to illuminate at least a portion of an environment around the vehicle700with light pulses and detect reflected light pulses. Based on the detection of reflected light pulses, information about the environment may be determined. The information determined from the reflected light pulses may be indicative of distances and directions to one or more objects in the environment around the vehicle700. For example, the information may be used to generate point cloud information that relates to physical objects in the environment of the vehicle700. The information could also be used to determine the reflectivities of objects in the environment, the material composition of objects in the environment, or other information regarding the environment of the vehicle700.

The information obtained from one or more of sensor systems702,704,706,708, and710could be used to control the vehicle700, such as when the vehicle700is operating in an autonomous or semi-autonomous mode. For example, the information could be used to determine a route (or adjust an existing route), speed, acceleration, vehicle orientation, braking maneuver, or other driving behavior or operation of the vehicle700.

VII. Example methods

Described herein are example methods and processes that could be implemented in any of the configurations described above, including the sensing device102illustrated inFIGS.1and3, the sensing devices102a-102dillustrated inFIG.2, the rotary link400illustrated inFIGS.4and5, and the LIDAR device600illustrated inFIG.6. However, the described methods and processes described could be implemented in other systems or devices as well.

FIG.8is a flowchart of a method800, according to example embodiments. Method800may include one or more operations, functions, or actions as illustrated by one or more of blocks802-810. Although the flowchart shows the blocks802-810as occurring in a particular order, one or more of the blocks could be performed in a different order and/or could be performed simultaneously.

At block802, method800involves rotating a rotating portion of a sensing device relative to a stationary portion of the sensing device. The rotating portion is spaced apart from the stationary portion by a gap. The rotation could be caused, for example, by a motor in the rotating portion. In example embodiments, the rate of rotation is between 3 Hz and 60 Hz and the gap is on the order of 1 mm (e.g., between 0.5 and 1.5 mm). However, other rates of rotations and gap dimensions are possible as well.

At block804, the method800involves generating data by one or more sensors in the rotating portion. The one or more sensors may include one or more light detectors, image sensors, radio receivers, accelerometers, gyroscopes, magnetometers, motor encoders, or other types of sensors, as well as associated electronics (e.g., analog-to-digital converters), depending on the nature of the sensing device.

At block806, the method800involves encoding, by a communication interface in the rotating portion, the data generated by the one or more sensors with error correction codes to provide encoded data. The error correction codes could be, for example, forward error correction codes, such as low-density parity-check (LDPC) codes.

At block808, the method800involves modulating, by the communication interface, a radio frequency (RF) signal with the encoded data to provide a data-modulated RF signal. In example embodiments, the RF signal includes a plurality of sub-carriers and the data-modulated RF signal is an OFDM signal. In such embodiments, the frequencies of the sub-carriers could be greater than 1 MHz and less than 1 GHz. For example, the plurality of sub-carriers may occupy a range of frequencies, such as 2-50 MHz or 2-200 MHz. The resulting data-modulated RF signal may provide a data rate that is greater than 100 Mbits/second.

At block810, the method involves transmitting, by the communication interface, the data-modulated RF signal to the stationary portion via a wireless data transformer. The wireless data transformer comprises a first conductive structure in the stationary platform and a second conductive structure in the rotating portion, such that the first and second conductive structures are inductively coupled together across the gap.

In some embodiments, blocks804-810are performed at the same time that block802is performed. Thus, the one or more sensors may generate data and the communication interface may encode the data to provide encoded data, modulate an RF signal (e.g., an RF signal comprising a plurality of sub-carriers) to provide a modulated RF signal, and transmit the modulated RF signal to the stationary portion via the wireless data transformer, while the rotating portion is rotating relative to the stationary portion.

In some embodiments, the method800further involves receiving, by the communication interface, a further data-modulated RF signal via the wireless data transformer. The communication interface may demodulate the further data-modulated RF signal to recover further encoded data. The communication interface may decode the further encoded data to recover further data. The communication interface may transmit the further data to an application processor or other component in the rotating portion.

In some embodiments, the method800further involves transmitting power to the rotating portion via a wireless power transformer that comprises a primary winding in the stationary portion and a secondary winding in the rotating portion. The primary and secondary windings are inductively coupled together across the gap.

In some embodiments, the stationary portion includes a first platform and the rotating portion includes a second platform, with the gap between the stationary and rotating portions being between the first platform and the second platform. In such embodiments, the first conductive structure may be disposed in the first platform and the second conductive structure may be disposed in the second platform. The first conductive structure may be a first conductive loop and the second conductive structure may be a second conductive loop. The first and second conductive loops could be, for example, single-turn loops or multi-turn loops. In some embodiments, the first and second conductive loops could be formed by conductive traces on respective PCBs. Thus, the first platform may include a first PCB with conductive traces that form a first conductive loop, and the second platform may include a second PCB with conductive traces that form a second conductive loop.

In some embodiments, the first and second platforms may include additional conductive structures that provide a wireless power transformer. For example, the first platform may include a primary winding and the second platform may include a secondary winding. In such embodiments, the first conductive structure (e.g., first conductive loop) may at least partially surround the primary winding, and the second conductive structure (e.g., second conductive loop) may at least partially surround the secondary winding. Further, a high magnetic permeability material (e.g., ferrite) may be disposed between the primary winding and the first conductive structure and/or between the secondary winding and the second conductive structure.

VIII. Conclusion

The particular arrangements shown in the Figures should not be viewed as limiting. It should be understood that other implementations may include more or less of each element shown in a given Figure. Further, some of the illustrated elements may be combined or omitted. Yet further, an exemplary implementation may include elements that are not illustrated in the Figures. Additionally, while various aspects and implementations have been disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations.