Patent Publication Number: US-2022236380-A1

Title: Rotating sensor assembly

Description:
BACKGROUND 
     Vehicles, such as autonomous or semi-autonomous vehicles, typically include a variety of sensors. Some sensors detect internal states of the vehicle, for example, wheel speed, wheel orientation, and engine and transmission variables. Some sensors detect the position or orientation of the vehicle, for example, global positioning system (GPS) sensors; accelerometers such as piezo-electric or microelectromechanical systems (MEMS); gyroscopes such as rate, ring laser, or fiber-optic gyroscopes; inertial measurements units (IMU); and magnetometers. Some sensors detect the external world, for example, radar sensors, scanning laser range finders, light detection and ranging (LIDAR) devices, and image processing sensors such as cameras. A LIDAR device detects distances to objects by emitting laser pulses and measuring the time of flight for the pulse to travel to the object and back. Some sensors are communications devices, for example, vehicle-to-infrastructure (V2I) or vehicle-to-vehicle (V2V) devices. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of an example vehicle including an example sensor assembly. 
         FIG. 2  is a perspective of the sensor assembly. 
         FIG. 3  is a top cross-sectional view of the sensor assembly. 
         FIG. 4  is a diagram of a control system and cleaning system of the sensor assembly. 
         FIG. 5  is a top view of a portion of the vehicle including the sensor assembly. 
         FIG. 6  is a side view of a nozzle of the sensor assembly. 
     
    
    
     DETAILED DESCRIPTION 
     A sensor assembly includes a base mounted to a vehicle defining a forward direction, a housing mounted to the base and rotatable relative to the base around an axis in a direction of rotation, a sensing apparatus inside the housing and rotatable with the housing, a sensor window fixed to and rotatable with the housing, the sensor window being flat, and a nozzle fixed relative to the base. The sensing apparatus has a field of view through the sensor window. The nozzle is positioned to be aimed at the sensor window when the sensor window is at a first rotational position that is more than 0° and less than 90° from the forward direction relative to the axis in the direction of rotation. 
     The sensor assembly may lack nozzles positioned to be aimed at the sensor window when the sensor window is more than 90° and less than 360° from the forward direction relative to the axis in the direction of rotation. 
     The nozzle may be positioned below a lowest point of the housing. 
     The nozzle may be a first nozzle, the sensor assembly may further include a second nozzle fixed relative to the base and positioned to be aimed at the sensor window when the sensor window is at a second rotational position that is more than 0° and less than 90° from the forward direction relative to the axis in the direction of rotation. The second rotational position may be the same as the first rotational position. 
     The sensor assembly may further include a motor arranged to rotate the housing in the direction of rotation relative to the base. The sensor assembly may further include a computer communicatively coupled to the motor, and the computer may be programmed to instruct the motor to rotate the housing in the direction of rotation at a constant speed. The sensor assembly may further include a valve actuatable to control fluid flow to the nozzle, the computer may be communicatively coupled to the valve and programmed to instruct the valve to open for an activation period, and the activation period may be at least two full rotations of the housing at the constant speed. 
     The sensor window may be rectangular. The nozzle may define a spray angle extending from a bottom to a top of the sensor window when the sensor window is in the first rotational position. 
     The sensor window may extend from the housing in a direction that is radially outward and circumferential relative to the axis. 
     The sensor window may extend circumferentially around the axis for at most 45°. 
     The sensor window may be one of at least one sensor window, and the at least one sensor window may collectively extend circumferentially around the axis for at most 90°. The at least one sensor window may include two sensor windows, and each of the sensor windows may extend for at most 45°. The two sensor windows may be rotationally symmetrically by 180° around the axis with respect to each other. 
     The sensor window may be recessed in the housing. 
     The housing may have a constant cross-section along the axis from a bottom of the sensor window to a top of the sensor window. 
     With reference to the Figures, a sensor assembly  102  includes a base  104  mounted to a vehicle  100  defining a forward direction F, a housing  106  mounted to the base  104  and rotatable relative to the base  104  around an axis A in a direction of rotation D, a sensing apparatus  108  inside the housing  106  and rotatable with the housing  106 , a sensor window  110  fixed to and rotatable with the housing  106 , and a nozzle  130  fixed relative to the base  104 . The sensor window  110  is flat. The sensing apparatus  108  has a field of view through the sensor window  110 . The nozzle  130  is positioned to be aimed at the sensor window  110  when the sensor window  110  is at a first rotational position that is more than 0° and less than 90° from the forward direction F relative to the axis A in the direction of rotation D. 
     The sensor assembly  102  provides for efficient cleaning of the sensor window  110  while minimizing the effect of washer fluid on the sensor window  110 . The fact that the sensor window  110  rotates obviates a need to have nozzles encircling the housing  106 ; instead, the nozzle  130  can be located at a particular location and spray the sensor window  110  as the housing  106  makes each revolution. The fact that the nozzle  130  is positioned to spray the sensor window  110  when the sensor window  110  is at the first rotational position, as opposed to other circumferential positions that the nozzle  130  could occupy, provides a longer time for the sensor window  110  to dry before the sensor window  110  faces in the forward direction F, specifically at least the time required to rotate 270°. In other words, spray from the nozzle  130  strikes the sensor window  110  when the sensor window  110  is less than a quarter rotation since facing straight forward, so the sensor window  110  has more than three quarters of a rotation before facing straight forward again. Data from the sensing apparatus  108  is comparatively more important in the forward direction F than other directions because the vehicle  100  most frequently travels in the forward direction F. 
     With reference to  FIG. 1 , the vehicle  100  may be any suitable type of automobile, e.g., a passenger or commercial automobile such as a sedan, a coupe, a truck, a sport utility vehicle, a crossover vehicle, a van, a minivan, a taxi, a bus, etc. The vehicle  100 , for example, may be an autonomous vehicle. In other words, the vehicle  100  may be autonomously operated such that the vehicle  100  may be driven without constant attention from a driver, i.e., the vehicle  100  may be self-driving without human input. Autonomous operation can be based in part on data received from the sensor assembly  102 . 
     The vehicle  100  includes a vehicle body  112 . The vehicle body  112  includes body panels  114  partially defining an exterior of the vehicle  100 . The body panels  114  may present a class-A surface, e.g., a finished surface exposed to view by a customer and free of unaesthetic blemishes and defects. The body panels  114  include, e.g., a roof  116 , etc. 
     A casing  118  for the sensor assembly  102  and other sensors is attachable to the vehicle  100 , e.g., to one of the body panels  114  of the vehicle  100 , e.g., the roof  116 . For example, the casing  118  may be shaped to be attachable to the roof  116 , e.g., may have a shape matching a contour of the roof  116 . The casing  118  may be attached to the roof  116 , which can provide the first sensing apparatus  108   a  and a second sensing apparatus  108   b  of the sensor assembly  102  with an unobstructed field of view of an area around the vehicle  100 . The casing  118  may be formed of, e.g., plastic or metal. The sensor assembly  102  is supported by the casing  118 . The sensor assembly  102  can be disposed on top of the casing  118  at a highest point of the casing  118 . 
     With reference to  FIG. 2 , the sensor assembly  102  includes the base  104 . The base  104  is attached to the casing  118  on top of the casing  118 . The base  104  can be bolted to the casing  118 , e.g., through bolt holes in the base  104 . The base  104  is mounted to the vehicle  100 , e.g., via the casing  118 , and the vehicle  100  defines a forward direction F, i.e., a direction of forward travel for the vehicle  100 . 
     The sensor assembly  102  includes a motor  120 . The motor  120  is arranged to drivably rotate the housing  106  in the direction of rotation D about the axis A. The motor  120  can be positioned, e.g., inside the base  104 . The motor  120  can be, e.g., an electric motor. 
     The housing  106  is mounted to the base  104  and rotatable relative to the base  104  around the axis A in the direction of rotation D. For example, the housing  106  can be mounted, e.g., fastened, to a sensor body (not shown). The sensor body can be rotatably attached to the base  104  and drivable by the motor  120 . The housing  106  can cover a top and sides of the sensor body. 
     The sensing apparatuses  108  are disposed inside the housing  106  and are rotatable with the housing  106 . For example, the sensing apparatuses  108  are mounted to and fixed relative to the sensor body, and thereby fixed relative to the housing  106 . The second sensing apparatus  108   b  can be a same type of sensor as the first sensing apparatus  108   a . The sensing apparatuses  108  may be designed to detect features of the outside world; for example, the sensing apparatuses  108  may be radar sensors, scanning laser range finders, light detection and ranging (LIDAR) devices, or image processing sensors such as cameras. In particular, the sensing apparatuses  108  may be LIDAR devices, e.g., scanning LIDAR devices. A LIDAR device detects distances to objects by emitting laser pulses at a particular wavelength and measuring the time of flight for the pulse to travel to the object and back. The first sensing apparatus  108   a  has a field of view through the first sensor window  110   a  encompassing a region from which the first sensing apparatus  108   a  receives input, and the second sensing apparatus  108   b  has a field of view through a second sensor window  110   b  encompassing a region from which the second sensing apparatus  108   b  receives input. As the sensing apparatuses  108  rotate with the housing  106 , the fields of view encompass a horizontal 360° around the vehicle  100 . 
     The sensor assembly  102  can include at least one sensor window  110 , e.g., two sensor windows  110 . The sensor windows  110  are fixed relative to the housing  106  and rotatable with the housing  106 . The housing  106  includes respective openings  122 , e.g., a first opening  122   a  and a second opening  122   b , in which the sensor windows  110  are positioned. 
     The sensor windows  110  have a collective circumferential extent around the axis A, that is, a collective angular sweep covered by the sensor windows  110 . The circumferential extent around the axis A of each sensor window  110  is an angle θ formed at the axis A between a clockwisemost point and a counterclockwisemost point of that sensor window  110 , i.e., an angular sweep around the axis A from one circumferential end of that sensor window  110  to the other circumferential end of that sensor window  110 . For example, the sensor windows  110  can collectively extend circumferentially around the axis A for at most 90°. The first sensor window  110   a  and the second sensor window  110   b  can each extend circumferentially around the axis A for at most 45°. The comparatively small angular sweep of the sensor windows  110  with respect to the housing  106  provides a small area to keep clean and is accommodated by the fact that the housing  106  and the sensor windows  110  rotate. 
     The sensor windows  110  can be flat. For example, the sensor windows  110  can have a rectangular shape. The sensor windows  110  are transparent with respect to whatever medium the sensing apparatuses  108  are capable of detecting. For example, if the sensing apparatuses  108  are LIDAR devices, then the sensor windows  110  are transparent with respect to visible light at the wavelength generated and detectable by the sensing apparatuses  108 . 
     With reference to  FIG. 3 , the housing  106  includes at least one outer wall  124 , at least one window wall  126 , and at least one nonwindow wall  128 . For example, the housing  106  includes a first outer wall  124   a , a first window wall  126   a , a first nonwindow wall  128   a , a second outer wall  124   b , a second window wall  126   b , and a second nonwindow wall  128   b.    
     The housing  106  can be rotationally symmetric, e.g., second-degree rotationally symmetric. For the purposes of this disclosure, “rotationally symmetric” means looking the same after some rotation by a partial turn around an axis A. A degree of rotational symmetry is a number of distinct orientations in which something looks the same for each rotation. The housing  106  has second-degree rotational symmetry, and the housing  106  looks the same when rotated by 180° so that the second outer wall  124   b , the second window wall  126   b , and the second nonwindow wall  128   b  occupy the space previously occupied by the first outer wall  124   a , the first window wall  126   a , and the first nonwindow wall  128   a , respectively. Specifically, the second outer wall  124   b , the second window wall  126   b , and the second nonwindow wall  128   b  are rotationally symmetric by 180° around the axis A with respect to the first outer wall  124   a , the first window wall  126   a , and the first nonwindow wall  128   a , respectively. The sensor windows  110  are also rotationally symmetric by 180° around the axis A with respect to each other. The following descriptions of the first outer wall  124   a , the first window wall  126   a , the first sensor window  110   a , and the first nonwindow wall  128   a  apply as well to the second outer wall  124   b , the second window wall  126   b , the second sensor window  110   b , and the second nonwindow wall  128   b , respectively. 
     The first outer wall  124   a  has a partial cylindrical shape extending circumferentially at a constant outer radius from the axis A. The first outer wall  124   a  extends circumferentially at the constant outer radius from the second nonwindow wall  128   b  to the first window wall  126   a . The first outer wall  124   a  extends circumferentially for at least 90°. Because of the constant outer radius, the rotational motion of the first outer wall  124   a  does not displace air for the circumferential extent of the first outer wall  124   a , providing smooth airflow onto the first nonwindow wall  128   a . The first outer wall  124   a  extends vertically, i.e., parallel to the axis A, from below the sensor windows  110  to above the sensor windows  110 . 
     The first window wall  126   a  is flat and parallel to the first sensor window  110   a . The first window wall  126   a  extends completely around the first sensor window  110   a , i.e., below, above, and to the sides. The first window wall  126   a  includes the first opening  122   a  in which the first sensor window  110   a  is positioned. The first window wall  126   a  extends from the first outer wall  124   a  to the first nonwindow wall  128   a . The first window wall  126   a  extends in a direction tangent to the first outer wall  124   a . The first window wall  126   a  extends vertically, i.e., parallel to the axis A, from below the first sensor window  110   a  to above the first sensor window  110   a.    
     The first sensor window  110   a  is parallel to the first window wall  126   a . The first sensor window  110   a  is recessed in the first window wall  126   a . The first sensor window  110   a  extends from a point on the housing  106 , e.g., the point on the first opening  122   a  that is closest to the axis A, which is also a point nearest the first outer wall  124   a , in a direction that is radially outward and circumferential relative to the axis A. The first sensor window  110   a  is disposed farther from the axis A than the outer radius of the first outer wall  124   a . An exterior surface of the first sensor window  110   a  faces in a direction that is radially outward and circumferentially in the direction of rotation D relative to the axis A. For the purposes of this disclosure, a direction that a surface “faces” is a direction that is normal, i.e., perpendicular or orthogonal, to that surface. 
     The first nonwindow wall  128   a  extends from the first window wall  126   a  to the second outer wall  124   b . The first nonwindow wall  128   a  can be flat. The first nonwindow wall  128   a  extends in a radially inward direction and possibly a circumferential direction from the first window wall  126   a  relative to the axis A. The first nonwindow wall  128   a  can be nontangent to the second outer wall  124   b . An exterior surface of the first nonwindow wall  128   a  faces in a direction that is radially outward and circumferentially away from the direction of rotation D relative to the axis A. The first nonwindow wall  128   a  extends vertically, i.e., parallel to the axis A, from below the sensor windows  110  to above the sensor windows  110 . 
     The housing  106 , specifically the first outer wall  124   a , the first window wall  126   a , the first nonwindow wall  128   a , the second outer wall  124   b , the second window wall  126   b , and the second nonwindow wall  128   b , can have a constant cross-section from a bottom of the sensor windows  110  to a top of the sensor windows  110 . Except for the openings  122 , the housing  106  can have a constant cross-section from a distance below the sensor windows  110  to a distance above the sensor windows  110 . The constant cross-section can reduce forces tending to roll or pitch the housing  106  as the housing  106  rotates. 
     With reference to  FIG. 4 , the sensor assembly  102  includes a cleaning system  132  of the vehicle  100 . The cleaning system  132  includes a reservoir  134 , a pump  136 , valves  138 , supply lines  140 , and the nozzles  130 . The reservoir  134 , the pump  136 , and the nozzles  130  are fluidly connected to each other (i.e., fluid can flow from one to the other). The cleaning system  132  distributes washer fluid stored in the reservoir  134  to the nozzles  130 . “Washer fluid” is any liquid stored in the reservoir  134  for cleaning. The washer fluid may include solvents, detergents, diluents such as water, etc. 
     The reservoir  134  may be a tank fillable with liquid, e.g., washer fluid for window cleaning. The reservoir  134  may be disposed in the casing  118 . Alternatively, the reservoir  134  may be disposed at a front of the vehicle  100 , specifically, in an engine compartment forward of a passenger cabin. The reservoir  134  may store the washer fluid only for supplying the sensor assembly  102  or also for other purposes, such as supply to the windshield. 
     The pump  136  may force the washer fluid through the supply lines  140  to the nozzles  130  with sufficient pressure that the washer fluid sprays from the nozzles  130 . The pump  136  is fluidly connected to the reservoir  134 . The pump  136  may be attached to or disposed in the reservoir  134 . 
     Each valve  138  is positioned and actuatable to control fluid flow from the pump  136  to one of the nozzles  130 . Specifically, fluid from the supply lines  140  from the pump  136  must flow through one of the valves  138  to reach the respective supply line  140  providing fluid to the respective nozzle  130 . The valves  138  control flow by being actuatable between an open position permitting flow and a closed position blocking flow from the incoming to the outgoing of the supply lines  140 . The valves  138  can be solenoid valves. As a solenoid valve, each valve  138  includes a solenoid and a plunger. Electrical current through the solenoid generates a magnetic field, and the plunger moves in response to changes in the magnetic field. The solenoid moves the plunger between a position in which the valve  138  is open and a position in which the valve  138  is closed. 
     The supply lines  140  extend from the pump  136  to the nozzles  130 . The supply lines  140  may be, e.g., flexible tubes. 
     As described in more detail below, the nozzles  130  are positioned to eject washer fluid onto the sensor assembly  102 , either the housing  106  or one of the sensor windows  110 , depending on the rotational position of the sensor windows  110 . 
     The sensor assembly  102  includes a control system  142 . The control system  142  includes a computer  144  and a communications network  146 . The computer  144  is a microprocessor-based computing device, e.g., a generic computing device including a processor and a memory, an electronic controller or the like, a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), etc. The computer  144  can thus include a processor, a memory, etc. The memory of the computer  144  can include media for storing instructions executable by the processor as well as for electronically storing data and/or databases, and/or the computer  144  can include structures such as the foregoing by which programming is provided. The computer  144  can be multiple computers coupled together. 
     The computer  144  may transmit and receive data through the communications network  146 . For example, the communications network  146  can be a controller area network (CAN) bus, Ethernet, WiFi, Local Interconnect Network (LIN), onboard diagnostics connector (OBD-II), and/or by any other wired or wireless communications network. The computer  144  may be communicatively coupled to the motor  120 , the pump  136 , the valves  138 , and other components via the communications network  146 . 
     The computer  144  is programmed to control the motor  120 . Specifically, the computer  144  is programmed to instruct the motor  120  to rotate the housing  106  at a constant speed. The speed of the motor  120  can be chosen based on a scanning speed of the sensing apparatuses  108  in order to quickly refresh data about the environment around the vehicle  100  while permitting the sensing apparatuses  108  to have complete coverage of the environment during rotation, e.g., 600 revolutions per minute. 
     The computer  144  is programmed to control the cleaning system  132 , specifically the pump  136  and the valves  138 . The computer  144  can instruct the cleaning system  132  to run a cleaning cycle in response to a cleaning trigger. For the purposes of this disclosure, a “cleaning trigger” is an event indicating that the sensor windows  110  should be cleaned. A first example of a cleaning trigger is an input from an operator of the vehicle  100 . A second example is data from the sensing apparatuses  108  indicating an obstruction of one of the sensor windows  110 , such as a region of the field of view being unchanging across different rotational positions of the sensor window  110 . A third example is a preset duration elapsing since the last cleaning. The preset duration can be chosen based on testing the sensor assembly  102  to determine how long can run before becoming sufficiently dirty that data from the sensing apparatuses  108  are affected. The cleaning cycle is running the pump  136 , opening the valves  138 , closing the valves  138 , and stopping the pump  136 . By default, i.e., when a cleaning cycle is not occurring, the pump  136  is not running, and the valves  138  are closed. Specifically, the computer  144  is programmed to, in response to a cleaning trigger, instruct the pump  136  to run, instruct the valves  138  to open for an activation period and then close, and instruct the pump  136  to stop running upon the valves  138  closing. The activation period is a duration that the valves  138  remain open before closing. The activation period is chosen based on a speed of operation of the valves  138 . The activation period lasts for multiple rotations of the housing  106 , i.e., is at least two full rotations of the housing  106  at the constant speed. 
     With reference to  FIG. 5 , the nozzles  130  are fixed relative to the base  104 . For example, the nozzles  130  are attached to an exterior of the casing  118  and are radially spaced from the housing  106  relative to the axis A. The nozzles  130  can include a first nozzle  130   a , a second nozzle  130   b , and possibly additional nozzles  130  (not shown). The first nozzle  130   a  is positioned to be aimed at the sensor window  110  when the sensor window  110  is at a first rotational position that is more than 0° and less than 90° from the forward direction F relative to the axis A in the direction of rotation D. (The first rotational position is the same for each sensor window  110  because the sensor windows  110  are rotationally symmetric.) In other words, spray from the first nozzle  130   a  strikes the sensor window  110  when the sensor window  110  is less than a quarter rotation since facing straight forward. The second nozzle  130   b  is positioned to be aimed at the sensor window  110  when the sensor window  110  is at a second rotational position that is more than 0° and less than 90° from the forward direction F relative to the axis A in the direction of rotation D. The second rotational position can be the same as the first rotational position so that the force of spray from multiple nozzles  130  strikes the sensor window  110  simultaneously. Alternatively, the second rotational position can be circumferentially offset from the first rotational position so that spray from the nozzles  130  strikes the sensor window  110  for a longer total duration. Additional nozzles  130  are positioned to be aimed at the sensor window  110  when the sensor window  110  is at respective additional positions that are more than 0° and less than 90° from the forward direction F relative to the axis A in the direction of rotation D. The additional rotational positions can be the same as the first or second rotational positions or circumferentially offset from the first or second rotational positions. The sensor assembly  102  lacks nozzles positioned to be aimed at the sensor window  110  when the sensor window  110  is more than 90° and less than 360° from the forward direction F relative to the axis A in the direction of rotation D, thereby permitting the sensor window  110  time to dry before facing the forward direction F. 
     With reference to  FIG. 6 , the nozzles  130  are positioned below a lowest point of the housing  106 . The nozzles  130  are shaped to spray upward at the sensor windows  110 . The nozzles  130  each define a spray angle extending from a bottom to a top of the sensor window  110  when the sensor window  110  is in the first or second rotational position, respectively. In other words, the spray from the nozzles  130  strikes a full height of the sensor window  110 . 
     In operation, the motor  120  rotates the housing  106  and sensor windows  110  at the constant speed while the vehicle  100  is operating. When a cleaning trigger occurs, the cleaning system  132  performs a cleaning cycle. The nozzles  130  spray at the respective first or second rotational position for the activation period. During the activation period, the sensor windows  110  rotate completely around the axis A multiple times. During each rotation, each sensor window  110  passes through the first and second rotational positions, at which the spray from the first and second nozzles  130  strikes the sensor window  110  and washes off debris or dirt. After each time passing the first and second rotational positions, the sensor windows  110  rotate more than three quarters of a rotation before facing straight forward, during which the airflow across the sensor windows  110  and the centrifugal force from the rotation forces the washer fluid off of the sensor windows  110 . The sensor windows  110  are thus dried when facing forward even during the activation period. The activation period ends, and the nozzles  130  stop spraying. 
     The disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. The adjectives “first” and “second” are used throughout this document as identifiers and are not intended to signify importance, order, or quantity. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the disclosure may be practiced otherwise than as specifically described.