RF data link for devices with rotating components

Abstract

A radio frequency (RF) data link may be provided between a fixed base assembly and a rotating assembly that rotates about an axis defined by a shaft having a waveguide core (e.g., a hollow core). The rotating assembly may include a data source, such as one or more sensors. An RF transmitter unit may be disposed in the rotating assembly, and the RF transmitter unit may have a first antenna oriented to transmit to one end of the waveguide core of the shaft. The base assembly may include an RF receiver unit, which may have a second antenna positioned at the other end of the shaft and oriented to receive an RF signal through the waveguide core of the shaft. The waveguide core of the shaft may provide a waveguide for RF data transmission (e.g., in the millimeter wave band) between the first antenna and the second antenna.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 369,350, filed on July 25, 2022, which is incorporated herein by reference. Background Art

[0003] The present disclosure generally relates to electronic devices (such as lidar systems) having a rotating assembly mounted on a fixed base, and specifically to a radio frequency (RF) data link between the rotating assembly and the fixed base.

[0004] Imaging based on time of flight (ToF) is used for many applications, including ranging; depth profiling; and 3D imaging, such as optical imaging, detection, and ranging (LiDAR or laser radar). Direct time of flight (dToF) measurements include directly measuring the length of time between the emission of radiation from a transmitter element and the sensing of the radiation by a detector element after reflection from an object or other target. The distance to the target can be determined from the measured length of time. Indirect time of flight measurements include determining the distance to the target by phase modulating the amplitude of a signal emitted by a transmitter element of a laser radar system and measuring the phase (e.g., relative to a delay or shift) of an echo signal received at a detector element of the laser radar system. These phases can be measured with a series of separate measurements or samples. A typical laser radar system includes an array of transmitter elements and a corresponding array of detector elements. The transmitter elements and the detector elements can be arranged to concurrently sample depth information at different locations in the field of view.

[0005] To provide a 360-degree field of view, some lidar systems include a rotating assembly that houses the emitter and detector. The rotating assembly is coupled to a fixed base that includes a motor to spin the rotating assembly at a desired speed. The fixed base also typically includes a data interface to deliver detector data from the lidar system to other systems.

[0006] Before the data is delivered to an external system, the data must be transferred from the rotating assembly to the fixed base. Depending on the specific implementation, the rotating assembly can generate a large amount of data (e.g., up to gigabits per second). For some applications, real-time data transmission is required. Summary of the invention

[0007] Transmitting data at high speeds between a rotating component and a fixed (or base) component has proven challenging. Fixed wires provide high data rates; however, connecting wires between moving parts can create reliability issues, and fixed wires are not a viable option in situations where the rotating component rotates continuously in one direction. Some lidar systems use a slip ring interface, which includes metal contacts (such as brushes) that rub against a rotating ring, which in some cases may be a liquid mercury ring, to provide conductive transfer. However, slip ring constructions tend to be bulky, and the use of mercury can also cause environmental issues. Some lidar systems use an optical interface. For example, the axis around which the rotating component spins can be a hollow axis. An optical transmitter (such as one or more LEDs) can be placed on the rotating component at one end of the axis, and an optical receiver can be placed on the fixed component at the other end of the axis. Light pulses from the transmitter can propagate down the axis and be detected by the optical receiver, thereby enabling communication. However, optical communication may not provide sufficient data bandwidth for some applications. In addition, due to the physical properties of existing optical devices, optical communication may require careful temperature compensation. Therefore, an improved communication link may be required.

[0008] Certain aspects of the present disclosure relate to a radio frequency (RF) data link that provides data transmission between a rotating component and a fixed component of a system (such as a laser radar system). In some embodiments, a radio frequency (RF) data link may be provided between a first component (e.g., a fixed base) and a second component that rotates around an axis defined by a shaft having a waveguide core. The waveguide core may include a hollow region passing through the shaft, the hollow region having an inner sidewall that reflects RF electromagnetic waves at a frequency of interest (e.g., in a carrier frequency band of the data link). Alternatively, the waveguide core may be filled with a material or medium that is transparent to RF electromagnetic waves at a frequency of interest; the sidewalls of the core may have reflective properties at such frequencies. The second component (and / or the first component) may include a data source (such as one or more sensors). An (RF) transmitter unit may be provided in the second component, and the (RF) transmitter unit may have a first antenna that is oriented to transmit to one end of the waveguide core of the shaft. The first component may include an RF receiver unit having a second antenna positioned at the other end of the shaft and oriented to receive RF signals through the waveguide core of the shaft. The waveguide core of the shaft may provide a waveguide for RF data transmission (e.g., in the millimeter wave band) between the first antenna and the second antenna. In various embodiments, the first antenna may be optimized to transmit circularly polarized waves, and the second antenna may be optimized for signal coupling strength.

[0009] According to some embodiments of the present invention, a system may include: a first component (such as a fixed base); a shaft extending from a surface of the first component, the shaft defining a rotation axis and having a waveguide core; a second component mounted on the shaft and capable of rotating around the rotation axis; a radio frequency (RF) transmitter unit disposed in the second component, the RF transmitter unit including a first antenna positioned at a first end of the shaft and oriented to transmit to the waveguide core of the shaft; and an RF receiver unit disposed in the first component, the RF receiver unit including a second antenna positioned at a second end of the shaft and oriented to receive RF signals through the waveguide core of the shaft. The waveguide core of the shaft may provide a waveguide for RF data transmission between the first antenna and the second antenna. In some embodiments, the RF data transmission may be in a millimeter wave band (e.g., having a carrier frequency of approximately 60 GHz). In some embodiments, the first antenna may be configured, for example, in size and shape to generate circularly polarized RF waves, which may improve the uniformity of signal strength as the second component (including the first antenna) rotates around the axis of rotation. In some embodiments, each of the first antenna and the second antenna may be a patch antenna constructed on a substrate comprising a low-loss copper-clad laminate with a metal antenna shape printed on the surface of the substrate. In some embodiments, the waveguide core of the shaft may have a circular cross-section and have a diameter selected to reduce the propagation of unwanted electromagnetic modes. The RF data link between the RF transmitter unit and the RF receiver unit may be used to communicate any type of data, including but not limited to data from sensors (such as a lidar sensor array) disposed in the second component.

[0010] In some embodiments, the RF transmitter unit and the RF receiver unit may provide a high-speed data link in one direction (referred to herein as a "downlink"), while data transmission in the other direction (referred to herein as an "uplink") is provided using other techniques. For example, an optical transmitter unit may be mounted to the base and optically coupled to the waveguide core of the shaft, and an optical receiver unit may be mounted to the rotating assembly and optically coupled to the waveguide core of the shaft.

[0011] According to some embodiments of the present invention, a bidirectional RF data link can be provided. For example, some embodiments of a system may include: a base; a shaft extending from a surface of the base, the shaft defining a rotation axis and having a waveguide core; a rotating assembly mounted on the shaft and capable of rotating around the rotation axis, the rotating assembly including one or more sensors; a first radio frequency (RF) transceiver unit disposed in the rotating assembly, the first RF transceiver unit including a first antenna positioned at a first end of the shaft and oriented to transmit to the waveguide core of the shaft; and a second RF transceiver unit disposed in the base, the second RF transceiver unit including a second antenna located at a second end of the shaft and oriented to receive RF signals through the waveguide core of the shaft. The waveguide core of the shaft provides a waveguide for bidirectional RF data transmission between the first RF transceiver unit and the second RF transceiver unit.

[0012] In various embodiments, one of the components (e.g., the rotating component) may include a sensor array, such as a lidar sensor array or any other sensor array that generates data. The component may also include a sensor controller coupled to the sensor array. The sensor controller may be configured to provide some or all of the data generated by the sensor array to the RF transmitter (or transceiver) unit of the rotating component. In some embodiments, the sensor controller may also receive configuration data for the sensor array via the uplink (which may be, for example, an RF uplink or an optical uplink).

[0013] The following detailed description and attachment Figure 1 This disclosure will provide a better understanding of the nature and advantages of the claimed invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A 360 degree lidar system is shown in the context of an automotive application according to some embodiments.

[0015] Figure 2A A simplified perspective view of a spinning lidar system is shown according to some embodiments.

[0016] Figure 2B Shows Figure 2A Top view of the spin lidar system.

[0017] Figure 3 A simplified cross-sectional diagram of a spinning lidar system incorporating an RF data link is shown, according to some embodiments.

[0018] Figure 4A simplified cross-sectional view of components of an RF data link is shown according to some embodiments.

[0019] Figure 5A and Figure 5B Simplified top views of a transmit antenna and a receive antenna, respectively, are shown according to some embodiments.

[0020] Figure 6 is a simplified cross-sectional diagram showing additional details of an RF receiver unit according to some embodiments.

[0021] Figure 7 A simplified cross-sectional diagram of a bidirectional data link is shown according to some embodiments. DETAILED DESCRIPTION

[0022] For the purpose of illustration and description, the following description of exemplary embodiments of the present invention is presented. It is not intended to be exhaustive or to limit the claimed invention to the precise form described, and those skilled in the art will appreciate that many modifications and variations are possible. Embodiments have been selected and described in order to better explain the principles of the present invention and its practical application, so as to enable others skilled in the art to best carry out and utilize the present invention in various embodiments and with various modifications suitable for the specific purpose envisioned.

[0023] 1. LiDAR System Overview

[0024] Figure 1 A 360 degree LiDAR system 100 is shown in the context of an automotive application according to some embodiments. An automotive application of the LiDAR system is chosen here for illustration purposes only, and sensors and devices of the type described herein may be used in other types of vehicles, such as ships, airplanes, trains, and a variety of other applications where rotational sensors are useful, such as medical imaging, geodesy, mapping, archeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics, laser guidance, airborne laser amplitude mapping (ALSM), and laser altimetry. According to some embodiments, the LiDAR system 100 may be mounted on the roof of a vehicle 105, such as Figure 1 shown.

[0025] In some embodiments, the lidar system 100 includes a spinning lidar system 102, which may employ a rotating architecture in which the pointing direction (i.e., angular position) of the lidar system 102 may be scanned across all or a portion of a 360 degree field of view around a vehicle 105. In some embodiments, a pulsed output beam 111 from one or more transmitters in the lidar system 102 may be emitted into the surrounding environment, as shown. Objects in the path of the beam 111 may reflect portions 117 of the light 111, and these reflected portions 117 may propagate back to the spinning lidar system 102 and may be detected by photodetectors in the spinning lidar system 102. Based on the time difference between emission and detection, a calculation may be made to determine the distance (also referred to herein as the "range") of an object at a point 110 in the environment surrounding the vehicle from the lidar system. Although Figure 1 Only a single point 110 is shown at a given angular direction in FIG, but the spinning lidar system 102 may include an array of emitters (e.g., distributed above and below the z-axis) and a corresponding array of photodetectors for measuring depth values ​​at the corresponding array of points for any given orientation of the output beam 111. A two-dimensional (2D) array of emitters and photodetectors may also be used.

[0026] The spinning lidar system 102 can be mechanically rotated about the z-axis (as indicated by the clockwise rotation direction 115) to capture a lidar image of a full field of view of 360 degrees around the vehicle 105. In some embodiments, the rotation can be achieved by mechanical means, such as by mounting the spinning lidar system 102 to a rotating column or platform that can be driven by an electric motor. In other embodiments, the rotation can be achieved by other mechanical means, such as by using a galvanometer. In these and other embodiments, chip-based steering components and technologies can be used to further expand the field of view (e.g., along the z-axis); examples include the use of microchips that use one or more MEMS-based reflectors, such as digital micromirror (DMD) devices or digital light processing (DLP) devices, etc. In some embodiments, scanning can be achieved in part by non-mechanical means, such as by using electronic signals to steer one or more optical phased arrays. A combination of scanning techniques can be implemented. For the purposes of this disclosure, it is assumed that the sensor is mounted on a component that mechanically rotates or spins around an axis (commonly referred to as the z-axis).

[0027] Figure 2A A simplified perspective view of a spinning lidar system 200 is shown according to certain embodiments. Spinning lidar system 200 may be used, for example, to implement Figure 1The spinning lidar system 102 is shown. The spinning lidar system 200 may include a rotating assembly 210 and a fixed assembly (also referred to as a "base") 220. The rotating assembly 210 may include a sensor array 212 as well as a microcontroller and other supporting components. In some embodiments, the sensor array 212 may include one or more emitters (e.g., vertical cavity semiconductor lasers (VCSELs) or edge emitting lasers, etc.) and corresponding photodetectors (e.g., avalanche photodiodes (APDs), single photon avalanche diodes (SPADs), or can be used for the above reference Figure 1 Any specific implementation of a lidar sensor and / or any other sensor may be provided.

[0028] Rotating assembly 210 may be rotatably mounted to base 220. Base 220 is referred to herein as "fixed" to indicate that it provides a reference frame for the rotation of rotating assembly 220; however, it should be understood that base 220 need not be fixed relative to the environment in which system 200 operates. For example, base 220 may be mounted on a vehicle. Base 220 may include system controller 222, a motor ( Figure 2A The base 220 may also include mechanical features (such as mounting fixtures, etc.).

[0029] In some embodiments, housing 250 may extend from base 220 to enclose rotating assembly 210. Housing 250 may include optically transparent window 260 (which may extend up to 360 degrees around the sides of scanning lidar system 200) and cover 270. Housing 250 may protect sensor array 212 and other components from the elements and provide a fixed exterior surface and / or aesthetic benefits.

[0030] Figure 2B A simplified top view of a spinning lidar system 200 is shown, as seen looking down along the z-axis at the lidar system 200 with the cover 270 removed. At any given point in time, the rotating assembly 210 may be pointing in a particular angular direction θ (which may be measured relative to a fixed reference direction (such as along the y-axis shown)), and the sensor array 212 may be operated to generate distance and intensity values ​​for objects in the field along that particular direction. As the rotating assembly 210 rotates (e.g., spins) about the z-axis, distance and brightness values ​​may be measured for multiple directions (e.g., as defined by the time / rate used to perform the measurements). Thus, the spinning lidar system 200 may provide a 360-degree panoramic view of the volume surrounding it.

[0031] In some embodiments, the rotating assembly 210 may rotate, for example, at a speed of 10 to 50 revolutions per second, and a depth image of a 360-degree field of view may be captured at a corresponding frame rate. Depending on factors such as the number of sensors and the frame rate, the sensor array 212 may be able to generate data at a high rate (e.g., several gigabits per second). In order to make the sensor data available in real time outside the lidar system 200, it is necessary to communicate the data from the sensor array 212 to the system controller 222 as the sensor array 212 rotates.

[0032] 2.RF data link

[0033] According to some embodiments of the present invention, a spinning laser radar system (such as laser radar system 200) may include a radio frequency (RF) data link to support data transmission from sensor array 212 (or other devices in rotating assembly 210) to fixed base 220. In some embodiments, the RF data link may operate at a carrier frequency in the millimeter wave band. As used herein, "millimeter wave band" includes wavelengths of about 1 mm to about 10 mm, corresponding to frequencies in air of about 30 GHz to 300 GHz. In some embodiments, the carrier frequency may be between 50 GHz and 65 GHz, and may be about 60 GHz, for example, 60.5 GHz in some specific implementations. If desired, other wavelengths may also be used, including wavelengths outside the millimeter wave band. The central axis supporting the rotation of rotating assembly 210 around the z-axis may provide a waveguide for efficient RF signal transmission between a first antenna positioned in or on rotating assembly 210 and a second antenna positioned in or on base 220.

[0034] Figure 3 3 is a simplified cross-sectional view of a spinning lidar system 200 in combination with an RF data link according to some embodiments. The rotating assembly 210 and the (fixed) base 220 may be coupled by a shaft 320 extending outwardly from the base 220. The shaft 320 may be, for example, a hollow cylindrical structure that is fixedly attached to the base 220 at one end. The housing of the rotating assembly 210 may include a cavity defined by a sidewall 330 into which the shaft 320 is inserted. A friction-reducing mechanism (such as a bearing or a fluid, etc.) may be introduced between the sidewall 330 and the shaft 320 to allow the rotating assembly 210 to rotate around the shaft 320 with low friction.

[0035] The rotating assembly 210 may include a sensor array 212, a sensor controller 310, and an RF transmitter (TX) unit 312. The sensor array 212 may be a lidar sensor array as described above, and may be implemented using one or more integrated circuits and / or discrete components. Any number and combination of sensors may be included; in addition to the detector, the sensor array 212 may also include light emitters or other components that generate stimuli in the environment. Data communication as described herein is independent of the details of sensor operation or data generation, and the sensor array 212 may include one or more sensors of any type and / or a combination of different types of sensors. The sensor controller 310 may include a microprocessor, a microcontroller, an ASIC, or an FPGA, etc. In operation, the sensor controller 310 may enable and disable the sensor array 212, control the operation of each emitter and / or sensor, and receive data from the sensor array 212. In some embodiments, the sensor controller 310 may perform processing operations on the data received from the sensor array 212. The sensor controller 310 may also prepare the data for transmission to the fixed base 220. For example, the sensor controller 310 may generate a data structure that associates a particular data value with a particular sensor within the sensor array 212 and / or a particular timestamp; additionally or alternatively, the sensor controller 310 may generate a data packet containing the data. If desired, the data packet generated by the sensor controller 310 may contain an error detection code and / or a forward error correction code. Regardless of any particular structure or format of the data, the controller 310 may provide a data stream to the RF transmitter unit 312.

[0036] The RF transmitter unit 312 may include an RF transmitter circuit system and an antenna. The RF transmitter circuit system may generate an RF carrier signal (e.g., at a frequency of about 60 GHz or other millimeter wave frequencies), generate an analog data signal from a digital data stream provided by the sensor controller 310, and modulate the analog data signal onto the carrier signal (e.g., using amplitude shift keying, phase shift keying, or a combination thereof), thereby generating a drive signal for the antenna. The antenna may be configured to direct the RF signal toward the base 220. An example implementation of the RF transmitter unit 312 is described below.

[0037] The base 220 may include a system controller 222, a motor controller 326, an RF receiver (RX) unit 324, and an external data interface 328. The motor controller 326 may include electrical and / or mechanical elements to operate a motor (not shown) to rotate the rotating assembly 210 around the axis 320. Data communications as described herein are independent of the details of the motor operation, and any type of motor and control mechanism may be used to generate the rotation of the rotating assembly 210. The external data interface 328 may include components that implement wired and / or wireless data communication protocols that enable communication with systems external to the system 200. For example, the external data interface 328 may include a USB port, a USB-C port, other wired communication ports, and / or a transceiver for wireless communication (e.g., implementing Bluetooth or Wi-Fi standards). The external data interface 328 may be a bidirectional communication interface that supports the transmission of data from the lidar system 200 to an external system (including sensor data obtained from the sensor array 212 via an RF data link), as well as receiving configuration and control signals from the external system.

[0038] The RF receiver unit 324 may include an antenna and RF receiver circuitry. The antenna may be sensitive to the RF signal generated by the RF transmitter unit 312. The RF receiver circuitry may demodulate the received RF signal and perform baseband processing to recover a digital data stream, which may be delivered to the system controller 222. An example implementation of the RF receiver unit 324 is described below.

[0039] The system controller 222 may include a microprocessor, a microcontroller, an ASIC or an FPGA, etc. In operation, the system controller 222 may act as a master controller for the spinning lidar system 200. For example, the system controller 222 may receive control signals via the external data interface 328 and generate control signals for other system components (such as the motor controller 326 and / or the sensor array 212). The system controller 222 may also receive sensor data from the RF receiver unit 324 and output some or all of the data via the external data interface 328. In some embodiments, the system controller 222 may perform processing operations on the received data and may output any combination of the received data and / or the results of the processing operations.

[0040] Figure 4A simplified cross-sectional view of components of an RF data link 400 according to some embodiments is shown. RF data link 400 may be implemented in a spinning lidar system 200 or other system having a fixed base and a rotating (e.g., spinning) component. For ease of description, it is assumed that RF data link 400 is used to transmit data from a rotating component (e.g., rotating component 210 described above) to a fixed component (e.g., base 220 described above); this direction may be referred to as a "downlink" direction.

[0041] The RF data link 400 includes a transmitter unit 410 (e.g., implementing the RF transmitter unit 312) and a receiver unit 420 (e.g., implementing the RF receiver unit 324), which are positioned at opposite ends of a shaft 320 (e.g., implementing the shaft 430), the center of which defines an axis of rotation (referred to herein as the "z-axis"). The receiver unit 424 may be fixedly coupled to the shaft 430, while the transmitter unit 410 is capable of rotating about the z-axis.

[0042] The shaft 430 may be a structure having a generally cylindrical shape of a waveguide core 432. In some embodiments, the waveguide core 432 may be a hollow core defined by the inner surface of the sidewall 434 of the shaft 430. The area within the waveguide core 432 may be filled with air or any other RF transparent medium. In other specific implementations, a separate waveguide structure may be inserted into or fabricated within the shaft 430. A variety of waveguide structures may be used, provided that the waveguide structure may propagate RF electromagnetic radiation having a frequency associated with the RF data link 400 from one end to the other. As described below, the waveguide core 432 may act as a waveguide for propagating RF signals between the transmitter unit 410 and the receiver unit 420. In some embodiments, the waveguide core 432 may have a cylindrical shape, which may reduce the angular dependence of the RF signal coupling efficiency; however, other shapes are not excluded. The outer surface of the side wall 434 of the shaft 430 can be smooth and cylindrical, or can incorporate various surface features that may be desired, such as for mechanical coupling between a rotating component and a fixed component; examples include channels for bearings, retaining features for limiting movement of a rotating component along the z-axis, etc.

[0043] The transmitter unit 410 may include a printed circuit board (PCB) 412 having a transmission antenna 416 mounted on one side adjacent to the shaft 430 and a transmitter chip 414 mounted on the opposite side. Figure 4414 and the transmit antenna 416. Similarly, the receiver unit 420 may include a PCB 422 having a receive antenna 426 and a receiver chip 424, the receive antenna being mounted on one side adjacent to the axis 430 and the receiver chip being mounted on the opposite side. Figure 4 426). In some embodiments, the transmitter chip 414 and the receiver chip 424 may be off-the-shelf components tuned to the same carrier frequency. For example, the ST60 RF transmitter chip and receiver chip currently available from STMicroelectronics may be used. Other transmitters and receivers may also be used.

[0044] In some embodiments, antennas 416 and 426 may be planar patch antennas tuned to the carrier frequency of transmitter chip 414 and receiver chip 424 . Figure 5A and Figure 5B Simplified top views of antenna 416 and antenna 418 are shown, respectively, according to some embodiments. Antennas 416, 418 can be manufactured using dielectric substrates 502, 542 having stable dielectric constants (including, for example, small variations with temperature). In some embodiments, the substrate can be a low-loss copper clad laminate (CCL), such as RO4350B CCL available from Rogers Corp. Copper or other conductive materials can be used to print the desired antenna shape 504, 544 onto one surface of the respective substrate 5042, 542. The antenna shapes 504, 544 can be symmetrical or asymmetrical as desired. In various embodiments, asymmetrical antenna shapes can provide more uniform performance over a range of rotational speeds, while symmetrical shapes can provide optimal performance at a particular rotational speed. Electrical contact pads can be formed on the back side ( Figure 5A and Figure 5B 502, 542) and connected to the antenna shapes 504, 544 through vias through the respective substrates 502, 542. In some embodiments, the contact pads may be implemented as a land grid array (LGA) or using other surface mounting technologies.

[0045] Figure 64 is a simplified cross-sectional view showing additional details of the receiver unit 420 according to some embodiments. PCB 422 can be a multilayer PCB of any desired size and shape. In some embodiments, PCB 422 can provide a main logic board for base 220, and system controller 222 and other components can be mounted on PCB 422. Alternatively, PCB 422 can be a secondary logic board that holds RF receiver unit 420 (and optionally other components) and has a connector or cable attachment, etc. to electrically couple to the main logic board. Receiver chip 424 can be mounted on one side of PCB 422. For example, receiver chip 424 can be provided in a ball grid array (BGA) package that can be soldered to PCB 422. Antenna 426 can be mounted to the opposite side of PCB 422, for example, using solder 626. Antenna 426 can include, for example, an antenna shape 644 printed on one side of substrate 642. As shown, vias 628 may extend through substrate 642 of antenna 426, and vias 630 may extend through PCB 422, thereby providing electrical connections between antenna 426 and receiver chip 424. (Although only one connection path is shown, it should be understood that any number of connections may exist.) Figure 6 As shown, assembly of the receiver unit 420 may be accomplished using conventional mounting and soldering techniques. The transmitter unit 410 may be similarly constructed.

[0046] Reference again Figure 4 , the transmitter unit 410 and the receiver unit 420 may be arranged so that the antennas 416 and 426 are oriented toward the axis 430. Specifically, the antennas 416 and 426 may be disposed within openings of the waveguide core 432 at opposite ends of the axis 430. Thus, the waveguide core 432 may act as a waveguide for propagating RF signals from the transmit antenna 416 to the receive antenna 426 through the waveguide core 432. The sidewalls of the waveguide core 432 may be made of or coated with an RF reflective material. For example, the axis 430 may be made of aluminum and optionally coated with an organic solderability preservative (OSP) or the like. In some embodiments, RF absorbing materials may be selectively placed at the ends of the waveguide to reduce cavity resonances and maintain high bandwidth without obstructing the antennas 416, 426.

[0047] In this example, the transmitter unit 410 (including the transmit antenna 416) is incorporated into a rotating assembly (e.g., the rotating assembly 210 described above) and is assumed to operate while rotating relative to the receive antenna 426. In order to reduce signal strength fluctuations caused by changes in the rotation angle, the transmit antenna 416 can be optimized to produce circularly polarized RF waves, while the receive antenna 426 is optimized to couple to the waveguide (i.e., the waveguide core 430).

[0048] The size and shape of the antennas 416 and 426 and the length and diameter of the waveguide core 432 (also referred to as the inner diameter of the shaft 430) can be optimized to maximize signal strength, depending on other design constraints, such as the overall form factor, the desired range of rotational speeds, etc. For example, the diameter of the waveguide core 432 can be optimized to reduce the propagation of unwanted modes. The thickness and shape of the dielectric substrates 502, 542 of the antennas 416 and 426 and the shape of the antenna structures 504, 544 can also be optimized. The thickness of the two substrates does not need to be equal. For example, the transmit antenna substrate 504 can have a thickness of 10 mils, while the receive antenna substrate 544 has a thickness of 20 mils. The shaft 430 should be long enough to avoid significant near-field effects (e.g., at least one to two times the wavelength of the RF carrier, or about 5 mm to 10 mm for a 60 GHz carrier frequency). At the other extreme, the shaft 430 can be as long as desired, although the reduction in signal strength as the transmission path length increases may impose an upper limit given a particular combination of transmitter strength and receiver sensitivity. In some embodiments, a coating for the inner surface of the shaft 430 may be selected to reduce signal loss. The inner diameter of the shaft 430 may be optimized to reduce the propagation of unwanted modes. In one example, the inner diameter is 3.56 mm. More generally, RF simulation software may be used to achieve optimization of the antenna shape and antenna and waveguide dimensions for a particular carrier frequency and shaft length. The outer diameter of the shaft 430 does not affect the RF data link and may be selected based on design considerations unrelated to RF performance. Providing a circular cross-section for the waveguide core 432 may achieve rotational symmetry, thereby reducing the effect of rotation angle on signal strength; however, other shapes are not excluded.

[0049] In some embodiments, the RF data link 400 can support high data rates (e.g., about 4 Gbps in some implementations using a 60 GHz carrier frequency) in a compact form factor and at low manufacturing cost. A "design and forget" implementation is possible, where any further individual tuning of the assembled system can be omitted as long as all components are within manufacturing tolerances. Depending on the specific components used, the RF data link 400 can operate over a wide temperature range (e.g., from -40°C to 105°C). In some embodiments, the shaft 430 can provide sufficient electromagnetic shielding to prevent signals on the RF data link 400 from interfering with the operation of other components of the system in which the RF data link 400 is implemented. Such shielding can also prevent electromagnetic interference (EMI) between the system in which the RF data link 400 is implemented and other systems, and can also prevent eavesdroppers from intercepting transmissions on the RF data link 400. It should be noted that 60 GHz electromagnetic waves do not typically propagate significant distances in the air (this is largely due to the absorption of photons by water molecules in the air), and this can reduce the amount of shielding material required to achieve compliance with EMI regulations that may apply.

[0050] In some embodiments, the RF data link 400 may be implemented as a bidirectional link. For example, antennas 416, 426 may be operated as bidirectional antennas capable of operating in a transmission or reception mode, and the transmitter chip 414 and the receiver chip 424 may be enhanced with complementary chips or replaced with bidirectional transceiver chips. Various protocols may be used to time-multiplex uplink transmissions and downlink transmissions. As described above, in some embodiments, antennas 416, 426 may be optimized in different ways, wherein antenna 416 is optimized for transmission, and antenna 426 is optimized for reception, thereby supporting a high-bandwidth downlink with a data rate that may exceed 1 Gbps. Such optimization does not exclude the use of the same antennas 416, 426, wherein the transmitter role and the receiver role are reversed to provide an uplink signal path. The resulting uplink may have a lower bandwidth than the downlink, provided that the bandwidth is sufficient to transmit uplink data in a specific application. Alternatively, a separate transmitting antenna and receiving antenna may be provided at each end of the waveguide core 432. A dual antenna arrangement may require a wider waveguide core 432 than a single antenna arrangement to allow both pairs of antennas to be routed into the same waveguide.

[0051] 3. RF downlink with optical uplink

[0052] For some applications, the uplink direction and the downlink direction may have different data throughput requirements. In the examples herein, it is assumed that the downlink direction carries more data at a higher rate; the uplink may carry a smaller amount of data, and a lower data rate may be sufficient. For example, in the spinning lidar system 200 of FIG. 2 , the downlink carries a large amount of sensor data, while the uplink carries configuration data (e.g., a few hundred bytes to a few thousand bytes). Therefore, some embodiments combine an RF downlink with a lower bandwidth uplink optical coupling.

[0053] Figure 7A simplified cross-sectional view of a combined RF / optical data link 700 according to some embodiments is shown. The data link 700 includes an RF downlink (indicated by arrow 742) and an optical uplink (indicated by arrow 744), wherein both the downlink signal and the uplink signal propagate through a waveguide core 732 of a shaft 730. At the rotating (or upstream) end, an RF transmitter unit including an RF antenna 716 and a separate optical receiver unit including a light detector 736 may be mounted on the PCB 710. The RF transmit antenna 716 may be similar or identical to the transmit antenna 416 or other transmit antennas described above. The light detector 736 may include any detector capable of detecting an optical signal (such as an optical pulse having a specific wavelength). At the fixed (or downstream) end, an RF receiver unit including an RF antenna 726 and a separate optical transmitter unit including an optical transmitter 734 may be mounted on the PCB 720. The RF receive antenna 726 may be similar or identical to the receive antenna 426 or other receive antennas described above. The light emitter 734 may include a light emitting diode (LED) or other compact light source that can be modulated (e.g., pulse modulated) by a control circuit (not shown) to convey information. A variety of light emitters and detectors can be used, including components of conventional design. In some embodiments, the uplink bandwidth can reach the order of megabits per second, while the downlink bandwidth reaches the order of hundreds of megabits to gigabits per second. In addition to acting as a waveguide for RF waves, the waveguide core 732 of the shaft 730 can also provide a line-of-sight transmission path between the light emitter 734 and the light detector 736. In some embodiments, the antennas 724 and 726 can be offset from the center of the shaft 730 to provide space for the light emitter 734 and the light detector 736.

[0054] like Figure 7 As illustrated, the uplink and downlink can be implemented using different technologies, with one direction (e.g., downlink) using RF communication as described herein to support high bandwidth, while the other direction (e.g., uplink) uses a lower bandwidth option (such as optical communication). Other combinations are also possible, including a bidirectional RF link using a bidirectional antenna or two pairs of dedicated antennas.

[0055] 4. Additional Implementation Plan

[0056] Although the present invention has been described with reference to specific embodiments, it will be appreciated that variations and modifications are possible. The terms "rotating" and "fixed" are used to distinguish between the two components, since the rotating component rotates relative to the fixed component. The fixed component may be mounted on a mobile vehicle or other mobile platform, and need not be fixed relative to the earth or any other object in the environment. Although the embodiments described herein assume that the primary data source is included in the rotating component, and that the downlink goes from the rotating component to the fixed component, the reverse is not excluded.

[0057] The terms "downlink" and "uplink" are used herein to distinguish between the two directions of communication in a point-to-point data link. In the examples herein, "downlink" refers to the direction of data transmission from the sensor array toward another system component, while "uplink" refers to the opposite direction. However, such labeling is arbitrary, and it should be understood that an RF data link of the type described herein may be implemented for either direction or for both directions: only for the downlink; only for the uplink; or for both the downlink and the uplink. In the case where an RF data link is implemented only for the downlink (or only for the uplink), another type of data link (including an optical data link as described above) may be implemented for the opposite direction. An RF data link of the type described herein may also be implemented in an embodiment where a unidirectional data link is required.

[0058] Furthermore, while the waveguide core is described as being located in a shaft that is fixedly mounted to a fixed base, some alternative implementations may have the shaft fixedly mounted to the rotating assembly, or the shaft may be able to rotate relative to both assemblies. Furthermore, while the foregoing description refers to a "spinning" system, in which the rotating assembly can continuously rotate at least 360 degrees in the same direction, other rotational motions are not excluded; for example, the rotating assembly may oscillate back and forth 360 degrees or less.

[0059] Additionally, a LiDAR sensor array is used as an example of a rotating sensor array that may benefit from an RF data link as described herein. Those skilled in the art having the benefit of this disclosure will appreciate that an RF data link of the type described herein may be used with any system that includes a rotating sensor array, or more generally in any system that includes a component that generates data while rotating relative to a component that includes a data receiver.

[0060] Although various circuits and components are described herein with reference to specific blocks, it should be understood that these blocks are defined for ease of description and are not intended to imply a specific physical arrangement of component parts. These blocks do not need to correspond to physically different components, and the same physical components can be used to implement various aspects of multiple blocks. Components described as dedicated or fixed-function circuits can be configured to perform operations by providing appropriate arrangements of circuit components (e.g., logic gates, registers, switches, etc.); automated design tools can be used to generate appropriate arrangements of circuit components that implement the operations described herein. Components described as processors or microprocessors can be configured to perform the operations described herein by providing appropriate program codes. Depending on the manner in which the initial configuration is obtained, various blocks may or may not be reconfigurable. Embodiments of the present invention can be implemented in various devices including electronic devices implemented using a combination of circuit systems and software.

[0061] All processes described herein are also illustrative and can be modified. Within the scope of logic, operations can be performed in a different order than the order described; the above operations can be omitted or combined; and operations not explicitly described above can be added.

[0062] Unless expressly indicated to the contrary, the recitation of "a," "an," or "the" is intended to mean "one or more." Reference to "one" of a particular component, feature, or other element is not intended to exclude additional co-existing instances of that component, feature, or other element unless expressly indicated to the contrary. Unless expressly indicated to the contrary, the use of "or" is intended to mean an "inclusive or" rather than an "exclusive or."

[0063] Therefore, although the invention has been described with respect to particular embodiments, it should be understood that the invention is intended to cover all modifications and equivalents within the scope of the following claims.

Claims

1. A system, wherein the system include: First component; a shaft extending from a surface of the first component, the shaft defining an axis of rotation and having a waveguide core; a second component mounted on the shaft and rotatable about the rotational axis; a radio frequency (RF) transmitter unit disposed in the second assembly, the RF transmitter unit comprising a first antenna positioned at a first end of the shaft and oriented to transmit RF signals to the waveguide core of the shaft; as well as an RF receiver unit disposed in the first assembly, the RF receiver unit comprising a second antenna positioned at a second end of the shaft and oriented to receive the RF signal through the waveguide core of the shaft, The waveguide core of the shaft provides a waveguide for RF data transmission between the first antenna and the second antenna.

2. The system of claim 1, wherein the RF data transmission is in a millimeter wave frequency band.

3. The system of claim 1, wherein the first antenna is configured to generate circularly polarized RF waves.

4. The system of claim 1, wherein the waveguide core comprises a hollow core of the shaft.

5. The system of claim 1, wherein the second component comprises one or more sensors to generate data.

6. The system of claim 1 , wherein each of the first antenna and the second antenna is a patch antenna having: a substrate comprising a low-loss copper-clad laminate; and A metallic antenna shape is printed on a surface of the substrate. 7 . The system of claim 6 , wherein the substrate of the first antenna has a first thickness and the substrate of the second antenna has a second thickness, the second thickness being different from the first thickness.

8. The system according to claim 1, in: The RF transmitter unit includes an RF transmitter chip mounted on a first side of a first printed circuit board; The first antenna is a patch antenna mounted on a second side of the first printed circuit board, the second side being opposite to the first side of the first printed circuit board; and The second side of the first printed circuit board faces the axis.

9. The system according to claim 8, in: The RF receiver unit includes an RF receiver chip mounted on a first side of a second printed circuit board; the second antenna is a patch antenna mounted on a second side of the second printed circuit board, the second side being opposite to the first side of the second printed circuit board; and The second side of the second printed circuit board faces the axis.

10. The system of claim 1, wherein the waveguide core of the shaft has a circular cross-section and has a diameter selected to reduce propagation of unwanted electromagnetic modes.

11. The system according to claim 1, further comprising: include: an optical transmitter unit mounted to the first component and optically coupled to the waveguide core of the shaft; as well as An optical receiver unit is mounted to the second component and optically coupled to the waveguide core of the shaft.

12. The system of claim 11, wherein the second component include: Sensor arrays; as well as a sensor controller coupled to the sensor array, Wherein the sensor controller is configured to provide data from the sensor array to the RF transmitter unit and to receive configuration data of the sensor array from the optical receiver unit.

13. The system of claim 1, wherein the second end of the shaft is fixedly attached to the first component.

14. A system according to claim 1, wherein the second component includes a lidar sensor array, the lidar sensor array is configured to generate data, and wherein the RF transmitter unit is configured to transmit at least some of the data generated by the lidar sensor array.

15. A system, wherein the system include: Base; a shaft extending from a surface of the base, the shaft defining an axis of rotation and having a waveguide core; a rotating assembly mounted on the shaft and rotatable about the rotation axis, the rotating assembly including one or more sensors; a first radio frequency (RF) transceiver unit disposed in the rotating assembly, the first RF transceiver unit comprising a first antenna positioned at a first end of the shaft and oriented to transmit RF signals to the waveguide core of the shaft; as well as a second RF transceiver unit disposed in the base, the second RF transceiver unit comprising a second antenna located at a second end of the shaft and oriented to receive RF signals through the waveguide core of the shaft, wherein the waveguide core of the shaft provides a waveguide for bidirectional RF data transmission between the first RF transceiver unit and the second RF transceiver unit.

16. The system of claim 15, wherein the RF data transmission is in a millimeter wave frequency band.

17. The system of claim 15, wherein the waveguide core comprises a hollow core of the shaft.

18. The system of claim 15, wherein the first antenna is configured to generate circularly polarized RF waves.

19. The system of claim 18, wherein the second RF transceiver unit further comprises a third antenna positioned at the second end of the shaft and oriented to transmit into the waveguide core of the shaft, wherein the third antenna is configured to generate circularly polarized RF waves.

20. The system of claim 15, wherein each of the first antenna and the second antenna is a patch antenna having: a substrate comprising a low-loss copper-clad laminate; and A metallic antenna shape is printed on a surface of the substrate.

21. The system of claim 15, wherein the waveguide core of the shaft has a circular cross-section and has a diameter selected to reduce propagation of unwanted electromagnetic modes.

22. The system according to claim 15, further comprising: include: a laser radar sensor array, the laser radar sensor array being disposed in the rotating assembly; as well as a sensor controller coupled to the lidar sensor array, The sensor controller is configured to provide data from the lidar sensor array to the first RF transceiver unit and to receive configuration data of the lidar sensor array from the first RF transceiver unit.

23. The system of claim 22, wherein the second RF transceiver unit is configured to transmit configuration data of the lidar sensor array.

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