Patent Publication Number: US-10768063-B1

Title: Systems and methods for using piezoelectric sensors to ensure securement of enclosures

Description:
FIELD OF THE INVENTION 
     This disclosure relates to autonomous vehicles. More particularly, this disclosure relates to securement of an enclosure of an autonomous vehicle. 
     BACKGROUND 
     In general, an autonomous vehicle (e.g., a driverless vehicle, a semi-autonomous vehicle, etc.) can have myriad sensors onboard the autonomous vehicle. For example, the myriad sensors can include light detection and ranging sensors (LiDARs), radars, cameras, etc. The myriad sensors can play a central role in functioning of the autonomous vehicle. For example, a LiDAR can be utilized to detect and identify objects (e.g., other vehicles, road signs, pedestrians, buildings, etc.) in a surrounding. The LiDAR can also be utilized to determine relative distances of the objects to the LiDAR in the surrounding. As another example, radars can be utilized to aid with collision avoidance, adaptive cruise control, blind side detection, etc. As yet another example, cameras can be utilized to recognize, interpret, and/or analyze contents or visual cues of the objects. Data collected from these sensors can then be processed and used, as inputs, to make driving decisions. In general, sensors onboard the autonomous vehicle need to be aligned before the sensors can be used by the autonomous vehicle to make driving decisions. 
     SUMMARY 
     Various embodiments of the present disclosure can include systems and methods configured for securing an enclosure to an autonomous vehicle. The enclosure can be translated to a final alignment location on a fixture of the autonomous vehicle. The enclosure can include one or more piezoelectric sensors disposed underneath one or more mounting points of the enclosure. The one or more piezoelectric sensors can be initialized to an initial value. Changes in values from the one or more piezoelectric sensors can be measured as the enclosure is being secured to the fixture by one or more mechanical coupling devices through the one or more mounting points. 
     In some embodiments, the measured values from the one or more piezoelectric sensors can be converted into corresponding torque values. A notification can be emitted when a measured value corresponding to a desired torque value is reached. 
     In some embodiments, the notification can be an audio cue. 
     In some embodiments, the notification can be a visual cue. 
     In some embodiments, the measured values from the one or more piezoelectric sensors can be converted into corresponding torque values based on a calibration curve. 
     In some embodiments, the calibration curve can be at least one of a linear curve, a polynomial curve, or an exponential curve. 
     In some embodiments, the measured values from the one or more piezoelectric sensors can be converted into corresponding torque values based on a lookup table. 
     In some embodiments, the values measured by the one or more piezoelectric sensors can correspond to pressure exerted between the enclosure and the fixture. 
     In some embodiments, the enclosure can encase a LiDAR and cameras. 
     In some embodiments, the one or more mechanical coupling devices can include at least one of a screw, a nut and bolt, a rivet, or a fastener. 
     These and other features of the systems, methods, and non-transitory computer readable media disclosed herein, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for purposes of illustration and description only and are not intended as a definition of the limits of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain features of various embodiments of the present technology are set forth with particularity in the appended claims. A better understanding of the features and advantages of the technology will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings of which: 
         FIG. 1A  illustrates an example autonomous vehicle, according to an embodiment of the present disclosure. 
         FIG. 1B  illustrates an another example autonomous vehicle, according to an embodiment of the present disclosure. 
         FIG. 2  illustrates an example torque determination system, according to an embodiment of the present disclosure. 
         FIG. 3A  illustrates a cross-sectional view of an example torque determination system, according to an embodiment of the present disclosure. 
         FIG. 3B  illustrates an example of an enclosure for a sensor system according to an embodiment of the present disclosure. 
         FIG. 4  illustrates a torque measurement scenario, according to an embodiment of the present disclosure. 
         FIG. 5  illustrates an example method, according to an embodiment of the present disclosure. 
         FIG. 6  illustrates a block diagram of a computer system. 
     
    
    
     The figures depict various embodiments of the disclosed technology for purposes of illustration only, wherein the figures use like reference numerals to identify like elements. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated in the figures can be employed without departing from the principles of the disclosed technology described herein. 
     DETAILED DESCRIPTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various embodiments of the invention. However, one skilled in the art will understand that the invention may be practiced without these details. Moreover, while various embodiments of the invention are disclosed herein, many adaptations and modifications may be made within the scope of the invention in accordance with the common general knowledge of those skilled in this art. Such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way. 
     Unless the context requires otherwise, throughout the present specification and claims, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.” Recitation of numeric ranges of values throughout the specification is intended to serve as a shorthand notation of referring individually to each separate value falling within the range inclusive of the values defining the range, and each separate value is incorporated in the specification as it were individually recited herein. Additionally, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. The phrases “at least one of,” “at least one selected from the group of,” or “at least one selected from the group consisting of,” and the like are to be interpreted in the disjunctive (e.g., not to be interpreted as at least one of A and at least one of B). 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment, but may be in some instances. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     In general, an autonomous vehicle (e.g., a driverless vehicle, a semi-autonomous vehicle, etc.) can have myriad sensors onboard the autonomous vehicle. The myriad sensors can include light detection and ranging sensors (LiDARs), radars, cameras, global positioning systems (GPS), sonars, inertial measurement units (IMUs), accelerometers, gyroscopes, magnetometers, far infrared sensors (FIR), etc. The myriad sensors can play a central role in functioning of the autonomous vehicle. For example, a LiDAR can be utilized to detect and identify objects (e.g., other vehicles, road signs, pedestrians, buildings, etc.) in a surrounding. The LiDAR can also be utilized to determine relative distances of the objects to the LiDAR in the surrounding. As another example, radars can be utilized to aid with collision avoidance, adaptive cruise control, blind side detection, assisted parking, etc. As yet another example, cameras can be utilized to recognize, interpret, and/or analyze contents or visual cues of the objects. Cameras and other optical sensors can capture image data using charge coupled devices (CCDs), complementary metal oxide semiconductors (CMOS), or similar elements. An IMU may detect abnormal occurrences such as a bump or pothole in a road. Data collected from these sensors can then be processed and used, as inputs, to make driving decisions (e.g., acceleration, deceleration, direction change, etc.). For example, data from these sensors may be further processed into an image histogram of a graphical representation of tonal distribution in an image captured by the one or more sensors. 
     In general, sensors onboard an autonomous vehicle are highly calibrated or aligned. This means placement of sensors with respect to the autonomous vehicle need to be known within a high degree of confidence. Any deviation from the placement of sensors can lead to unreliable data. For example, a LiDAR relies on speed of light and position of laser beams to determine relative distances and locations of objects in a three dimensional surrounding. Data collected by the LiDAR is highly dependent (or calibrated) to a specific location to which the LiDAR is placed. Depending on where the LiDAR is located, the distances and the locations of the objects, as determined by the LiDAR, can vary. For instance, time it takes for a reflected light to reach a LiDAR located in the front of the autonomous vehicle will be different from time it takes for the same reflected light to reach a LiDAR located in the back of the autonomous vehicle. This slight time difference, in some cases, can make the distance and the location determinations not reliable for use in guiding the autonomous vehicle. To minimize number of sensor alignments, sensors, such as LiDARs and cameras, can be encased in an enclosure. The enclosure allows the sensors to be removed from one autonomous vehicle and installed to another autonomous vehicle with ease and without numerous alignments. For example, instead of removing sensors from one vehicle, and installing and aligning the sensors to another vehicle individually in multiple acts, an enclosure containing various sensors can be removed from one vehicle, and the enclosure can be installed and aligned to another vehicle in a single act. The enclosure can be affixed to a fixture on the roof (e.g., the top) of the autonomous vehicle using mechanical coupling devices (e.g., screws, nuts and bolts, rivets, etc.). These mechanical coupling devices can be tightened to a specific torque value to ensure that the enclosure is properly secured onto the fixture, and thus the autonomous vehicle. Under conventional approaches, one or more torque ranches can be used to tighten the mechanical coupling devices to specific torque values as intended. Each torque ranch is tuned to a specific torque value. In general, torque ranches are highly calibrated instruments and must be handled carefully because the torque ranches are very sensitive to various mechanical shocks (e.g., drops, dings, bumps, etc.). Any shocks, vibrations, or impacts to a torque ranch can reduce its ability to tighten a mechanical coupling device to a specific torque value that the ranch is tuned to. Accordingly, conventional approaches to secure an enclosure to a fixture of an autonomous vehicle using torque ranches can be cumbersome, bothersome, and inefficient. 
     The disclosed technology alleviates this and other problems under the conventional approaches. In various embodiments, the disclosed technology can utilize one or more piezoelectric sensors to measure torque values associated with securing an enclosure to a fixture using one or more mechanical coupling devices. The enclosure can be placed onto a fixture of an autonomous vehicle. The enclosure can be translated along an axis of the fixture. For example, the enclosure can move or glide forward or backward on the fixture along the body of the autonomous vehicle. In some embodiments, the enclosure can have one or more mounting points through which one or more mechanical coupling devices (e.g., screws, nuts and bolts, rivets, fasteners, etc.) can be used to secure the enclosure to the fixture. Each mounting point can be associated with a piezoelectric sensor. For example, an enclosure can have four mounting points that can be used to secure the enclosure to a fixture. In this example, there can be a piezoelectric sensor at or near each mounting point on the enclosure. In general, a piezoelectric sensor can measure pressure between any two surfaces. For example, a piezoelectric sensor disposed between an enclosure and a fixture can measure pressure exerted by the enclosure to the fixture. Once the enclosure is translated to a final alignment location on the fixture, initial pressure measurements from the one or more piezoelectric sensors of the enclosure can be “zeroed” or set to an initial value. As the one or more mechanical coupling devices are tightened to secure the enclosure to the fixture, pressure exerted by the enclosure to the fixture increases. This pressure can be measured by the one or more piezoelectric sensors and converted into corresponding torque values associated with the one or more mechanical coupling devices. In some embodiments, once the one or more mechanical coupling devices are tightened to a specific torque value as indicated by the pressure measurement, an audio or visual cue can be emitted to signify that the one or more mechanical coupling devices are at their proper torque values. Various embodiments are discussed herein in greater detail. 
       FIG. 1A  illustrates an example autonomous vehicle  100 , according to an embodiment of the present disclosure. An autonomous vehicle  100  generally refers to a category of vehicles that are capable of sensing and driving in a surrounding by itself. The autonomous vehicle  100  can include myriad sensors (e.g., LiDARs, radars, cameras, etc.) to detect and identify objects in the surrounding. Such objects may include, but not limited to, pedestrians, road signs, traffic lights, and/or other vehicles, for example. The autonomous vehicle  100  can also include myriad actuators to propel and navigate the autonomous vehicle  100  in the surrounding. Such actuators may include, for example, any suitable electro-mechanical devices or systems to control a throttle response, a braking action, a steering action, etc. In some embodiments, the autonomous vehicle  100  can recognize, interpret, and analyze road signs (e.g., speed limit, school zone, construction zone, etc.) and traffic lights (e.g., red light, yellow light, green light, flashing red light, etc.). For example, the autonomous vehicle  100  can adjust vehicle speed based on speed limit signs posted on roadways. In some embodiments, the autonomous vehicle  100  can determine and adjust speed at which the autonomous vehicle  100  is traveling in relation to other objects in the surrounding. For example, the autonomous vehicle  100  can maintain a constant, safe distance from a vehicle ahead (e.g., adaptive cruise control). In this example, the autonomous vehicle  100  maintains this safe distance by constantly adjusting its vehicle speed to that of the vehicle ahead. 
     In various embodiments, the autonomous vehicle  100  may navigate through roads, streets, and/or terrain with limited or no human input. The word “vehicle” or “vehicles” as used in this paper includes vehicles that travel on ground (e.g., cars, trucks, bus, etc.), but may also include vehicles that travel in air (e.g., drones, airplanes, helicopters, etc.), vehicles that travel on water (e.g., boats, submarines, etc.). Further, “vehicle” or “vehicles” discussed in this paper may or may not accommodate one or more passengers therein. Moreover, phrases “autonomous vehicles,” “driverless vehicles,” or any other vehicles that do not require active human involvement can be used interchangeably. 
     In general, the autonomous vehicle  100  can effectuate any control to itself that a human driver can on a conventional vehicle. For example, the autonomous vehicle  100  can accelerate, brake, turn left or right, or drive in a reverse direction just as a human driver can on the conventional vehicle. The autonomous vehicle  100  can also sense environmental conditions, gauge spatial relationships (e.g., distances between objects and itself), detect and analyze road signs just as the human driver. Moreover, the autonomous vehicle  100  can perform more complex operations, such as parallel parking, parking in a crowded parking lot, collision avoidance, etc., without any human input. 
     In various embodiments, the autonomous vehicle  100  may include one or more sensors. As used herein, the one or more sensors may include a LiDAR  102 , radars  104 , cameras  106 , GPSs, sonars, ultrasonic, IMUS, accelerometers, gyroscopes, magnetometers, FIRs, and/or the like. The one or more sensors allow the autonomous vehicle  100  to sense a surrounding around the autonomous vehicle  100 . For example, the LiDARs  102  can be configured to generate a three-dimensional map of the surrounding. The LiDARs  102  can also be configured to detect objects in the surrounding. As another example, the radars  104  can be configured to determine distances and speeds of objects around the autonomous vehicle  100 . As yet another example, the cameras  106  can be configured to capture and process image data to detect and identify objects, such as road signs, as well as analyzing content of the objects, such as speed limit posted on the road signs. 
     In the example of  FIG. 1A , the autonomous vehicle  100  is shown with the LiDAR  102  mounted to a roof or a top of the autonomous vehicle  100 . The LiDAR  102  can be configured to generate three dimensional maps and detect objects in the surrounding. In the example of  FIG. 1A , the autonomous vehicle  100  is shown with four radars  104 . Two radars are directed to the front-side and the back-side of the autonomous vehicle  100 , and two radars are directed to the right-side and the left-side of the autonomous vehicle  100 . In some embodiments, the front-side and the back-side radars can be configured for adaptive cruise control and/or accident avoidance. For example, the front-side radar can be used by the autonomous vehicle  100  to maintain a safe distance from a vehicle ahead of the autonomous vehicle  100 . As another example, if the vehicle ahead experiences a sudden reduction in speed, the autonomous vehicle  100  can detect this sudden change in motion, using the front-side radar, and adjust its vehicle speed accordingly. In some embodiments, the right-side and the left-side radars can be configured for blind-spot detection. In the example of  FIG. 1A , the autonomous vehicle  100  is shown with six cameras  106 . Two cameras are directed to the front-side of the autonomous vehicle  100 , two cameras are directed to the back-side of the autonomous vehicle  100 , and two cameras are directed to the right-side and the left-side of the autonomous vehicle  100 . In some embodiments, the front-side and the back-side cameras can be configured to detect, identify, and determine objects, such as cars, pedestrian, road signs, in the front and the back of the autonomous vehicle  100 . For example, the front-side cameras can be utilized by the autonomous vehicle  100  to identify and determine speed limits. In some embodiments, the right-side and the left-side cameras can be configured to detect objects, such as lane markers. For example, side cameras can be used by the autonomous vehicle  100  to ensure that the autonomous vehicle  100  drives within its lane. 
       FIG. 1B  illustrates an another example autonomous vehicle  140 , according to an embodiment of the present disclosure. In the example of  FIG. 1B , the autonomous vehicle  140  is shown with an enclosure  142  and four radars  144 . The enclosure  142  is mounted onto a fixture  146 . In some embodiments, the fixture  146  can be a roof rack or a custom rack fitted to the autonomous vehicle  140 . The enclosure  142 , when mounted onto the fixture  146 , can translate along a linear axis  148 . For example, once mounted onto the fixture  146 , the enclosure  142  can be adjusted to move in a forward or a backward direction with respect to the autonomous vehicle  140 , along the linear axis  148  of the fixture  146 . In some embodiments, the enclosure  142  can be moved along a nonlinear axis. In one embodiments, the enclosure  142  can include a LiDAR, a plurality of radars and cameras, and their associated electronics. In another embodiment, the enclosure  142  can include a LiDAR, a plurality of cameras, and their associated electronics. Many variations are possible. The enclosure  142  allows sensors to be packaged compactly or tightly and to be moved from one vehicle to another easily. In various embodiments, the enclosure  142  can be made from any materials that are transparent to electromagnetic waves emitted by or receptive to the sensors encased in the enclosure  142 . In various embodiments, an outer cover of the enclosure  142  can be made from tempered glass, plexiglass, chemically strengthened glass, and the likes. 
     In some embodiments, the enclosure  142  can include one or more piezoelectric sensors. The one or more piezoelectric sensors can measure pressure (or strain) between any two surfaces. A piezoelectric sensor is a type of sensor that converts pressure into electrical signal. The electrical signal can be digitized and analyzed by a computing system to determine torque values corresponding to the pressure between two surfaces. In some embodiments, a piezoelectric sensor can be disposed, in-line, between the enclosure  142  and the fixture  146 , or beneath the enclosure  142 . In such embodiments, one side of the piezoelectric sensor makes a contact with the enclosure  142  and the other side of the piezoelectric sensor makes a contact with the fixture  146 . In some embodiments, a plurality of piezoelectric sensors can be disposed at various mounting points of the enclosure  142 . For example, the enclosure  142  may have four mounting points through which the enclosure  142  can be secured, with mechanical coupling devices (e.g., screws, nuts and bolts, rivets, fasteners, etc.), to the fixture  146 . In this example, a piezoelectric sensor can be disposed at each mounting point of the enclosure  142  to determine torque value exerted by the mechanical coupling device at each mounting point. 
       FIG. 2  illustrates an example torque determination system  200 , according to an embodiment of the present disclosure. The example torque determination system  200  can include a torque determination engine  202  that can further include one or more processors and memory. The processors, in conjunction with the memory, can be configured to perform various operations associated with the torque determination engine  202 . For example, the processors and memory can determine torque exerted by a mechanical coupling device to secure an enclosure to a fixture of autonomous vehicle. The torque exerted can be determined based on pressure as measured by a piezoelectric sensor disposed between the enclosure and the fixture. As shown in  FIG. 2 , in some embodiments, the torque determination engine  202  can include a measurement initialization engine  204 , a torque conversion engine  206 , and a notification engine  208 . The measurement initialization engine  204 , the torque conversion engine  206 , and the notification engine  208  will be discussed in further detail below. 
     In some embodiments, the torque determination system  200  can additionally include at least one data store  210  that is accessible to the torque determination engine  202 . In some embodiments, the data store  210  can be configured to store parameters, data, configuration files, or machine-readable codes of the measurement initialization engine  204 , the torque conversion engine  206 , and the notification engine  206 . 
     In general, the torque determination engine  202  can determine a torque value associated with using a mechanical coupling device to secure an enclosure to a fixture of an autonomous vehicle. The torque determination engine  202  can determine the torque value based on pressure measured by a piezoelectric sensor disposed between the enclosure and the fixture. As discussed above, a piezoelectric sensor can measure pressure between two surfaces and can convert this pressure into electrical signal that can be further processed. To do so, an initial pressure measurement from the piezoelectric sensor is “zeroed” or set to an initial value (a baseline value). The torque determination engine  202  can utilize the measurement initialization engine  204  to initialize the electrical signal of the piezoelectric sensor. The measurement initialization engine  204  can establish the initial pressure measurement from the piezoelectric sensor as a baseline or initial value for pressure. Any subsequent changes to pressure between the enclosure and the fixture are measured in relation to the initial value. For example, if the pressure between the enclosure and the fixture is greater than the initial value, the pressure is expressed as some number or value larger than the initial value. As another example, if the pressure between the enclosure and the fixture is less than the initial value, the pressure is expressed as some number or value smaller than the initial value. The measurement initialization engine  204  will be discussed in further detail with respect to  FIG. 4  herein. 
     The torque conversion engine  206  can convert pressure measured by a piezoelectric sensor to torque values. The torque conversion engine  206  can convert pressure to torque values based on a calibration curve. For example, once a piezoelectric sensor has been initialized to an initial value (e.g., “zeroed”), any changes in pressure in relation to the initial value can be expressed as a mathematical function of torque value. For instance, a numerical change in pressure can be expressed as some change in torque value in accordance with the mathematical function. In some embodiments, the calibration curve can be a linear function, a polynomial function, or an exponential function. In some embodiments, the calibration curve can be a combination of the aforementioned functions. In some embodiments, the calibration curve can be implemented as a lookup table. Many variations are possible. 
     The notification engine  208  can generate a notification based on a torque value. The notification engine  208  can generate a notification once a desired torque value is reached as determined by the torque conversion engine  206 . For example, when a mechanical coupling device is tighten to a desired torque value, the notification engine  208  can generate a notification to a user that the desired torque value has been reached. In some embodiments, the notification engine  208  can generate a notification based on an audio cue. For example, the notification engine  208  can emit a discrete sound signature (e.g., a beeping sound) when the desired torque value is reached. In some embodiments, the notification engine  208  can generate a notification based on a visual cue. For example, the notification engine  208  can emit a pulsing light to indicate that the desired torque value is reached. Many variations are possible. 
       FIG. 3A  illustrates a cross-sectional view of an example torque determination system  300 , according to an embodiment of the present disclosure.  FIG. 3A  depict a scenario in which an enclosure is being translated and secured to a final alignment location on a fixture of an autonomous vehicle. As depicted, the torque determination system  300  includes an enclosure  302  mounted to a fixture  304  of an autonomous vehicle through one or more clamps (e.g., a clamp  308 ) at one or more mounting points associated with the enclosure  302 . The one or more clamps allows the enclosure  302  to translate (e.g., move, glide, etc.) to a final alignment location along the fixture  304 . In some embodiments, the enclosure  302  can include a piezoelectric sensor  310 , disposed between the enclosure  302  and the fixture  304 , underneath the enclosure  302 , at each mounting point. The piezoelectric sensor  310  can measure pressure exerted by the enclosure  302  to the fixture  304 . Once the enclosure  302  has been translated to the final alignment location, the piezoelectric sensor  310  can be zeroed or initialized to an initial value. This initialization allows the piezoelectric sensor  310  to measure pressure changes relative to the initial value. The enclosure  302  can be secured to the fixture  304  at the final alignment location using one or more mechanical coupling devices (e.g., a mechanical coupling device  306 ). The one or more mechanical coupling devices can be screws, nuts and bolts, rivets, fasteners, or Velcro, for example. As the one or more mechanical coupling devices are tightened to secure the enclosure  302 , the pressure exerted by the enclosure  302  to the fixture  304  at each mounting point, as measured by the piezoelectric sensor  310 , increases. This pressure can be converted to a torque value using a calibration curve as discussed with respect to  FIG. 2 . In some embodiments, once the torque value at each mounting point reaches a certain desired torque value, the torque determination system  300  can emit an audio cue informing that a mechanical coupling device (i.e., the mechanical coupling device  306 ) corresponding to a piezoelectric sensor (i.e., the piezoelectric sensor  310 ) has been tightened to the desired torque value. In some cases, instead of an audio cue, a visual cue, such as blinking lights, can be emitted. Many variations are possible. 
       FIG. 3B  illustrates an example of an enclosure  320  for a sensor system according to an embodiment of the present disclosure. The enclosure  320  may be implemented as enclosure  302 , for example.  FIG. 3B  may include a cover  362  to encase a sensor system, which may include LiDAR sensor  330  and cameras  332 . For example, the cover  362  may be detachable or removable to allow easy access to the sensor system. In some embodiments, the cover  362  can rotate circularly, or in three hundred sixty degrees, relative to the sensor system about a central vertical axis of the cover  362 . In some embodiments, the cover  362  may have a profile or shape that has a low wind resistance or coefficient of drag, and thereby reducing negative impacts to fuel economy of the autonomous vehicle. For example, the cover  362  may have a smooth surface so that a boundary layer formed between the air and the cover  362  would be laminar rather than turbulent. For example, the cover  362  may have a sleek angular profile. In some embodiments, the outer contour of the cover  362  can have multiple distinct sections (e.g., portions, regions, etc.) with different shapes. For example, a top portion of the cover  362  may have a circular dome shape with a first diameter measured at a base of the top portion and may encase the LiDAR sensor  330  of the autonomous vehicle. A middle portion of the cover  362  directly below the top portion may have a trapezoidal or truncated cone shape with a second diameter measured at a base on the middle portion, and the second diameter may be larger than the first diameter. A lower portion of the cover  362  directly below the middle portion may have a trapezoidal or truncated cone shape with a third diameter measured at a base on the lower portion. The third diameter may be larger than the second diameter. In other embodiments, the cover  362  may be entirely comprised of a single shape, such as a circular dome shape, a trapezoidal or truncated cone shape. 
     The cover  362  may be made from any suitable material that allows the one or more sensors of the enclosure  320  to properly function while shielding the one or more sensors from environmental elements (e.g., rain, snow, moisture, wind, dust, radiation, oxidation, etc.). Further, the suitable material must be transparent to wavelengths of light or electro-magnetic waves receptive to the LiDAR sensor  330  and the plurality of cameras  332 . For example, for the LiDAR sensor  330  to properly operate, the cover  362  must allow laser pulses emitted from the LiDAR sensor  330  to pass through the cover  362  to reach a target and then reflect back through the cover  362  and back to the LiDAR sensor  330 . Similarly, for the plurality of cameras  332  to properly operate, the cover  362  must allow visible light to enter. In addition to being transparent to wavelengths of light, the suitable material must also be able to withstand potential impacts from roadside debris without causing damages to the LiDAR sensor  330  or the plurality of cameras  332 . In an implementation, the cover  362  can be made of acrylic glass (e.g., Cylux, Plexiglas, Acrylite, Lucite, Perspex, etc.). In another implementation, the cover  362  can be made of strengthen glass (e.g., Coring® Gorilla® glass). In yet another implementation, the cover  362  can be made of laminated safety glass held in place by layers of polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or other similar chemical compounds. Many implementations are possible and contemplated. 
     In some embodiments, the cover  362  can be tinted with a thin-film neural filter to reduce transmittance of light entering the cover  362 . For example, in an embodiment, a lower portion of the cover  362  can be selectively tinted with the thin-film neutral filter to reduce an intensity of visible light seen by the plurality of cameras  332 . In this example, transmittance of laser pulses emitted from the LiDAR sensor  330  is not be affected by the tint because only the lower portion of the cover  342  is tinted. In another embodiment, the lower portion of the cover  362  can be tinted with a thin-film graduated neural filter in which the transmittance of visible light can vary along an axis. In yet another embodiment, the whole cover  362  can be treated or coated with a reflective coating such that the components of the enclosure  320  is not visible from an outside vantage point while still being transparent to wavelengths of light receptive to the LiDAR sensor  330  and the plurality of cameras  332 . Many variations, such as adding a polarization layer or an anti-reflective layer, are possible and contemplated. 
     In some embodiments, the enclosure  320  may comprise a frame  334 , a ring  336 , and a plurality of anchoring posts  338 . The frame  334  provides mechanical support for the LiDAR sensor  330  and the plurality of cameras  332 . The ring  336  provides mounting points for the cover  362  such that the cover  362  encases and protects the sensor system from environmental elements. The plurality of anchoring posts  338  provides mechanical couplings to secure or mount the enclosure  320  to the autonomous vehicle. 
     In some embodiments, the frame  334  may have two base plates held in place by struts  340 . An upper base plate of the frame  334  may provide a mounting surface for the LiDAR sensor  330  while a lower base plate of the frame  334  may provide a mounting surface for the plurality of cameras  332 . In general, any number of LiDAR sensors  330  and cameras  332  may be mounted to the frame  334 . The frame  334  is not limited to having one LiDAR sensor and six cameras as shown in  FIG. 3B . For example, in an embodiment, the frame  334  can have more than two base plates held in place by the struts  340 . In this example, the frame  334  may have three base plates with upper two base plates reserved for two LiDAR sensors  330  and a lower base plate for six cameras  332 . In another embodiment, the lower base plate can have more than six cameras  332 . For instance, there can be three cameras pointed in a forward direction of an autonomous vehicle, two cameras pointed to in a right and a left direction of the autonomous vehicle, and two cameras pointed in a reverse direction of the autonomous vehicle. Many variations are possible. 
     The frame  334  may include a temperature sensor  342 , a fan  344 , an air conditioning (AC) vent or cabin vent  346 , and a pressure sensor  355 . The temperature sensor  342  can be configured to measure a temperature of the enclosure  320 . In general, the temperature sensor  342  can be placed anywhere on the frame  334  that is representative of the enclosure temperature. In a typical implementation, the temperature sensor  342  is placed in a region in which heat generated by the LiDAR sensor  330  and the plurality of cameras  332  are most localized. In the example of  FIG. 3B , the temperature sensor  342  is placed on the lower base plate of the frame  334 , right behind the three front cameras. The fan  344  can be configured to draw an inlet airflow from an external source. The fan  344 , in various implementations, works in conjunction with the temperature sensor  342  to maintain a steady temperature condition inside the enclosure  320 . The fan  344  can vary its rotation speed depending on the enclosure temperature. For example, when the enclosure temperature is high, as measured by the temperature sensor  342 , the fan  344  may increase its rotation speed to draw additional volume of air to lower the temperature of the enclosure  320  and thus cooling the sensors. Similarly, when the temperature of the enclosure  320  is low, the fan  344  does not need to operate as fast. The fan  344  may be located centrally on the lower base plate of the frame  334 . The AC vent or cabin vent  346  may be a duct, tube, or a conduit that conveys cooling air into the enclosure  320 . In an embodiment, the AC vent or cabin vent  346  may be connected to a cabin of the autonomous vehicle. In another embodiment, the AC vent or cabin vent  346  may be connected to a separate air conditioner unit that provides cooling air separate from the cabin of the autonomous vehicle. The AC vent or cabin vent  346  may be directly connected to the enclosure  320  at a surface of the frame  334 . The pressure sensor  355  may be configured to determine an internal air pressure of the enclosure  320 . 
     In some embodiments, the frame  334  can also include a powertrain. The powertrain is an electric motor coupled to a drivetrain comprising one or more gears. The powertrain can rotate the ring  336  clockwise or counter-clockwise. In various embodiments, the electric motor can be a direct current brush or brushless motor, or an alternate current synchronous or asynchronous motor. Many variations are possible. In various embodiments, the one or more gears of the drivetrain can be configured to have various gear ratios designed to provide various amounts of torque delivery and rotational speed. 
     In general, the frame  334  can be made from any suitable materials that can withstand extreme temperature swings and weather various environmental conditions (e.g., rain, snow, corrosion, oxidation, etc.). The frame  334  can be fabricated using various metal alloys (e.g., aluminum alloys, steel alloys, etc.). The frame  334  can also be fabricated with three dimensional printers using thermoplastics (e.g., polylactic acid, acrylonitrile butadiene styrene, polyamide, high impact polystyrene, thermoplastic elastomer, etc.). Similarly, the air duct  346  can be made from rigid materials (e.g., hard plastics, polyurethane, metal alloys, etc.) or semi-rigid materials (e.g., rubber, silicone, etc.). Many variations are possible. 
     The ring  336  can provide mounting points for the cover  362  to encase the internal structure  304  of the enclosure  320 . In the example of  FIG. 3B , the ring  336  has an outer portion that includes attaching points  348  through which the cover  362  can be attached and secured. The ring  336  also has an inner portion that comprises gear teeth  350  (or cogs) such that when the gear teeth  350  is driven by the powertrain of the frame  334 , the whole ring  336  rotates as a result. 
     Similar to the frame  334 , the ring  336  can be made from any suitable material that can withstand extreme temperature swings and weather various environmental conditions. However, in most implementations, the suitable material for the ring  336  must be somewhat more durable than the material used for the frame  334 . This is because the gear teeth  350  of the ring  336  are subject to more wear and tear from being coupled to the powertrain of the frame  334 . The ring  336  can be fabricated using various metal alloys (e.g., carbon steel, alloy steel, etc.). The ring  336  can also be fabricated with three dimensional printers using thermoplastics (e.g., polylactic acid, acrylonitrile butadiene styrene, polyamide, high impact polystyrene, thermoplastic elastomer, etc.). 
     The plurality of the anchoring posts  338  can provide mechanical couplings to secure or mount the enclosure  320  to an autonomous vehicle. In general, any number of anchoring posts  338  may be used. In the example of  FIG. 3B , the enclosure  320  is shown with eight anchoring posts: four anchoring posts to secure the frame  334  to the autonomous vehicle and four anchoring posts to secure the ring  336  to the autonomous vehicle. Similar to the frame  334  and the ring  336 , the plurality of the anchoring posts  338  can be made from any suitable materials and fabricated using metal alloys (e.g., carbon steel, alloy steel, etc.) or three dimensional printed with thermoplastics (e.g., polylactic acid, acrylonitrile butadiene styrene, polyamide, high impact polystyrene, thermoplastic elastomer, etc.). 
     A first vent  354  and/or a second vent  356  may be disposed on the cover  362 . For example, the first vent  354  may be disposed on near the frame  344  or between the upper base plate of the frame  334  and the lower base plate of the frame  334 . For example, the second vent  356  may be disposed at or near the top of the cover  362 . The first vent  354  allows air from outside to flow into the enclosure  320 , and may be used to prevent humidification and/or overheating. The second vent  356  allows warm/hot air to be expelled from the enclosure  320 . The first vent  354  and/or the second vent  356  may be conducive to laminar flow of air. For example, a boundary layer created by the air entering and the first vent  354  would be laminar so that the boundary layer does not create turbulent flow. The first vent  354  and/or the second vent  356  may comprise a smooth orifice, and may be shaped to have a circular or elliptical cross section. The first vent  354  and/or the second vent  356  may be shaped so that the Reynolds number of air flowing through the second vent  356  may be at most 2000, to create laminar flow. In some embodiments, the Reynolds number of air flowing through the first vent  354  and/or the second vent  356  may be at most 3000, or at most 1000. 
     A controller  352  may be disposed on the frame  334 , the upper base plate of the frame  334 , or the lower base plate of the frame  334 . The controller  352  may control the operations of one of more of the LiDAR sensor  330 , the cameras  332 , the temperature sensor  342 , the fan  344 , the AC vent or cabin vent  346 , the first vent  354 , and/or the second vent  356 . 
     For example, the controller  352  may regulate a rotation speed of the fan  344  based on a speed of the vehicle, a temperature measured by the temperature sensor  342 , an external temperature, or a difference between the temperature measured by the temperature sensor  342  and the external temperature, and operate the fan  344  at the regulated rotation speed. For example, the controller  352  may regulate a rotation speed of the fan  344  based on any combination of the aforementioned factors. As an example, the controller  352  may regulate a rotation speed of the fan  344  based on whether the access from the enclosure  320  to the AC vent or cabin vent  346  is turned on. For example, the controller  352  may increase or decrease a rotation speed of the fan  344  if the access from the enclosure  320  to the AC vent or cabin vent  346  is turned off (e.g., no air flows from the AC vent or cabin vent  346  to the enclosure  320 ). For example, the controller  352  may increase or decrease a rotation speed of the fan  344  if the access from the enclosure  320  if the access from the enclosure  320  to the AC vent or cabin vent  346  is turned on. For example, the controller  352  may regulate a rotation speed of the fan  344  based on a level of wind external to the enclosure  320 . For example, the level of wind may be determined by an amount of airflow entering through the first vent  354 . For example, if enough air is entering through the first vent  354  to provide cooling and/or ventilation, the controller  352  may reduce the rotation speed of the fan  344  or shut off the fan  344 . Furthermore, the controller  352  may, in addition to, or instead of, regulating the rotation speed of the fan  344 , regulate an amount of air entering from the AC vent or cabin vent  346 , for example, depending or based on how much cooling is required for one or more of the sensors of the enclosure  320 . For example, the controller  352  may regulate the amount of air entering into the AC vent or cabin vent  346  based on one or more of, or any combination of, the speed of the autonomous vehicle, the temperature measured by the temperature sensor  342 , the external temperature, the difference between the temperature measured by the temperature sensor  342  and the external temperature, or based on an internal temperature of the LiDAR sensor  330  or the cameras  332  (which may indicate how heavily the LiDAR sensor  330  or the cameras  332  are being used). For example, the controller  352  may regulate the amount of air entering into the AC vent or cabin vent  346  by adjusting a size of an opening of the AC vent or cabin vent  346  (e.g., a radius of the opening of the AC vent or cabin vent  346 , or by regulating an amount of air extracted into the AC vent or cabin vent  346 . In another embodiment, the controller  352  may regulate an amount of air entering from the AC vent or cabin vent  346  based on the rotation speed of the fan  344 . For example, in one embodiment, if the rotation speed of the fan  344  is increased, the controller  352  may reduce the amount of air entering into the AC vent or cabin vent  346  because adequate cooling of the enclosure  320  may already be provided by the fan  344 . In one embodiment, the controller  352  may select between using the fan  344  and the AC vent or cabin vent  346  to cool the enclosure  320 . For example, the controller  352  may select between using the fan  344  and the AC vent or cabin vent  346  to cool the enclosure  320  based on which method is more energy efficient. In one embodiment, the controller  352  may select using the fan  344  when an amount of cooling to be provided (e.g. which may correspond to the temperature measured by temperature sensor  342 ) is lower than a threshold (e.g., first threshold) and using the AC vent or cabin vent  346  when the amount of cooling to be provided is greater than the threshold (e.g., first threshold). On the other hand, if the operation of the fan  344  at high rotation speed itself generates heat internally for the fan  344 , the controller  352  may increase the amount of air entering into, or permit air to enter through, the AC vent or cabin vent  346  to provide cooling for the fan  344 . Thus, the controller  352  may increase the amount of air entering into the AC vent or cabin vent  346  as the rotation speed of the fan  344  is increased. 
     The controller  352  may further be configured to turn on or turn off access from the AC vent or cabin vent  346  to the enclosure  320  based on the temperature of the enclosure  320  measured by the temperature sensor  342  or the internal air pressure of the enclosure  320  measured by the pressure sensor  355 . For example, an increase in the internal temperature of the enclosure  320  may result in changes in internal air pressure of a portion of the enclosure  320  because warmer air rises. To compensate for changes in the temperature and/or pressure inside the enclosure  320 , the AC vent or cabin vent  346  may be turned on to allow AC air or cabin air to flow into the AC vent or cabin vent  346 . Furthermore, the controller  352  may be configured to increase or decrease an amount of AC air or cabin air going into the enclosure  320 , for example, by increasing or decreasing a size of the AC vent or cabin vent  346 . In another embodiment, the controller  352  may be configured to increase or decrease an amount of AC air or cabin air, for example, based on a gradient of temperature inside the enclosure  320  or a gradient of pressure inside the enclosure  320 . As an example, if a gradient of temperature inside the enclosure  320  exceeds a threshold (e.g., second threshold), the controller  352  may be configured to increase or decrease an amount of AC air or cabin air. As an example, if a gradient of pressure inside the enclosure  320  exceeds a threshold (e.g., third threshold), the controller  352  may be configured to increase or decrease an amount of AC air or cabin air. 
     The controller  352  may further adjust a rotation speed of the fan  344 , and/or an amount of air entering the AC vent or cabin vent  346 , based on one or any combination of predicted future conditions, such as anticipated speed, anticipated external temperature, or anticipated internal temperature of the enclosure  320 . For example, if the controller  352  predicts, based on a navigation route selected, or weather forecast, that the temperature at a destination is high, the controller may preemptively precool the enclosure  320  by increasing the rotation speed of the fan  344  or increasing the amount of air entering the AC vent or cabin vent  346 . As another example, if the controller  352  predicts that the LiDAR sensor  330  or the cameras  332  will be heavily used in a near future, the controller may preemptively precool the enclosure  320  by increasing the rotation speed of the fan  344  or increasing the amount of air entering the AC vent or cabin vent  346 . As another example, if the controller  352  predicts that the vehicle speed will increase based on a type of road (e.g., highway), traffic conditions, road conditions, and/or amount of battery/gasoline remaining, the controller may preemptively precool the enclosure  320  by increasing the rotation speed of the fan  344  or increasing the amount of air entering the AC vent or cabin vent  346 . 
     Optionally, the enclosure  320  also comprises a filter  360 , or one or more filters  360 , to filter debris. In one embodiment, the filter  360  is a HEPA filter. The one or more filters  360  may be disposed on an upper base plate of the frame  334 , a lower base plate of the frame  334 , or the frame  334 . Additionally or alternatively, the one or more filters  360  may be disposed at an inlet of the first vent  354 . The activity of the filter  360  may be controlled by the controller  352 . For example, if a detected level of debris is high, the controller  352  may increase an activity level of the filter  360  (e.g. a heavy-duty mode). In contrast, if a detected level of debris is low, the controller  352  may decrease an activity level of the filter  360  (e.g. a light-duty mode). The filter  360  may further be adjusted to filter out particles of specific ranges of sizes (e.g., by the controller  352 ). 
       FIG. 4  illustrates a torque measurement scenario  400 , according to an embodiment of the present disclosure.  FIG. 4  depicts a scenario in which an enclosure is being translated and secured to a final alignment location on a fixture of an autonomous vehicle. In various embodiments, the enclosure can include one or more piezoelectric sensors at one or more mounting points of the enclosure. An example x-y plot is presented in  FIG. 4 . The x-y plot can represent a plot of pressure data measured by a piezoelectric sensor over a period of time spanning an alignment process for the enclosure. An x-axis of the x-y plot represents time. A y-axis of the x-y plot represents pressure data measured over the period of time spanning the alignment process. In the scenario  400  depicted, a region  402  on the plot corresponds to pressure data measured by the piezoelectric sensor (e.g., the piezoelectric sensor  310  of  FIG. 3A ) while the enclosure has not been mounted to the fixture. This pressure data (e.g., the region  402 ) represents no load value because the enclosure has not been mounted to the fixture. Once the enclosure is mounted to the fixture, the pressure data measured by the piezoelectric sensor increases due to pressure exerted by the enclosure to the fixture. This increase of pressure data is represented by a region  404  on the plot. At some time later, after the enclosure has been translated to the final alignment location, the pressure data from the piezoelectric sensor is “zeroed” or set to an initial value indicated by a point  406  on the plot. As the enclosure is secured with one or more mechanical coupling devices (e.g., screws, nuts and bolts, rivets, fasteners, etc.), the pressure data measured by the piezoelectric sensor increases again as indicated by a region  408  on the plot. This pressure data (e.g., the region  408 ) can be converted to torque values. As the one or more mechanical coupling devices are tightened, at some point, the pressure data as measured by the piezoelectric sensor will correspond to a desired torque value as indicated a point  410  on the plot. At this time, an audio or visual cue can be emitted to indicate that the desired torque value has been reached and the one or more mechanical coupling devices no longer need to be tightened. 
       FIG. 5  illustrates an example method  500 , according to an embodiment of the present disclosure. The operations of method  500  presented below are intended to be illustrative. Depending on the implementation, the example method  500  may include additional, fewer, or alternative steps performed in various orders or in parallel. The example method  500  may be implemented in various computing systems or devices including one or more processors. 
     At block  502 , an enclosure can be translated to a final alignment location on a fixture of an autonomous vehicle. The enclosure can include one or more piezoelectric sensors disposed underneath one or more mounting points of the enclosure. At block  504 , the one or more piezoelectric sensors can be initialized to an initial value. At block  506 , changes in values from the one or more piezoelectric sensors can be measured as the enclosure is being secured to the fixture by one or more mechanical coupling devices through the one or more mounting points. 
     Hardware Implementation 
     The techniques described herein are implemented by one or more special-purpose computing devices. The special-purpose computing devices may be hard-wired to perform the techniques, or may include circuitry or digital electronic devices such as one or more application-specific integrated circuits (ASICs) or field programmable gate arrays (FPGAs) that are persistently programmed to perform the techniques, or may include one or more hardware processors programmed to perform the techniques pursuant to program instructions in firmware, memory, other storage, or a combination. Such special-purpose computing devices may also combine custom hard-wired logic, ASICs, or FPGAs with custom programming to accomplish the techniques. The special-purpose computing devices may be desktop computer systems, server computer systems, portable computer systems, handheld devices, networking devices or any other device or combination of devices that incorporate hard-wired and/or program logic to implement the techniques. 
     Computing device(s) are generally controlled and coordinated by operating system software, such as iOS, Android, Chrome OS, Windows XP, Windows Vista, Windows 7, Windows 8, Windows Server, Windows CE, Unix, Linux, SunOS, Solaris, iOS, Blackberry OS, VxWorks, or other compatible operating systems. In other embodiments, the computing device may be controlled by a proprietary operating system. Conventional operating systems control and schedule computer processes for execution, perform memory management, provide file system, networking, I/O services, and provide a user interface functionality, such as a graphical user interface (“GUI”), among other things. 
       FIG. 6  is a block diagram that illustrates a computer system  600  upon which any of the embodiments described herein may be implemented. The computer system  600  includes a bus  602  or other communication mechanism for communicating information, one or more hardware processors  604  coupled with bus  602  for processing information. Hardware processor(s)  604  may be, for example, one or more general purpose microprocessors. 
     The computer system  600  also includes a main memory  606 , such as a random access memory (RAM), cache and/or other dynamic storage devices, coupled to bus  602  for storing information and instructions to be executed by processor  604 . Main memory  606  also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor  604 . Such instructions, when stored in storage media accessible to processor  604 , render computer system  600  into a special-purpose machine that is customized to perform the operations specified in the instructions. 
     The computer system  600  further includes a read only memory (ROM)  608  or other static storage device coupled to bus  602  for storing static information and instructions for processor  604 . A storage device  610 , such as a magnetic disk, optical disk, or USB thumb drive (Flash drive), etc., is provided and coupled to bus  602  for storing information and instructions. 
     The computer system  600  may be coupled via bus  602  to a display  612 , such as a cathode ray tube (CRT) or LCD display (or touch screen), for displaying information to a computer user. An input device  614 , including alphanumeric and other keys, is coupled to bus  602  for communicating information and command selections to processor  604 . Another type of user input device is cursor control  616 , such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor  604  and for controlling cursor movement on display  612 . This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane. In some embodiments, the same direction information and command selections as cursor control may be implemented via receiving touches on a touch screen without a cursor. 
     The computing system  600  may include a user interface module to implement a GUI that may be stored in a mass storage device as executable software codes that are executed by the computing device(s). This and other modules may include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. 
     In general, the word “module,” as used herein, refers to logic embodied in hardware or firmware, or to a collection of software instructions, possibly having entry and exit points, written in a programming language, such as, for example, Java, C or C++. A software module may be compiled and linked into an executable program, installed in a dynamic link library, or may be written in an interpreted programming language such as, for example, BASIC, Perl, or Python. It will be appreciated that software modules may be callable from other modules or from themselves, and/or may be invoked in response to detected events or interrupts. Software modules configured for execution on computing devices may be provided on a computer readable medium, such as a compact disc, digital video disc, flash drive, magnetic disc, or any other tangible medium, or as a digital download (and may be originally stored in a compressed or installable format that requires installation, decompression or decryption prior to execution). Such software code may be stored, partially or fully, on a memory device of the executing computing device, for execution by the computing device. Software instructions may be embedded in firmware, such as an EPROM. It will be further appreciated that hardware modules may be comprised of connected logic units, such as gates and flip-flops, and/or may be comprised of programmable units, such as programmable gate arrays or processors. The modules or computing device functionality described herein are preferably implemented as software modules, but may be represented in hardware or firmware. Generally, the modules described herein refer to logical modules that may be combined with other modules or divided into sub-modules despite their physical organization or storage. 
     The computer system  600  may implement the techniques described herein using customized hard-wired logic, one or more ASICs or FPGAs, firmware and/or program logic which in combination with the computer system causes or programs computer system  600  to be a special-purpose machine. According to one embodiment, the techniques herein are performed by computer system  600  in response to processor(s)  604  executing one or more sequences of one or more instructions contained in main memory  606 . Such instructions may be read into main memory  606  from another storage medium, such as storage device  610 . Execution of the sequences of instructions contained in main memory  606  causes processor(s)  604  to perform the process steps described herein. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions. 
     The term “non-transitory media,” and similar terms, as used herein refers to any media that store data and/or instructions that cause a machine to operate in a specific fashion. Such non-transitory media may comprise non-volatile media and/or volatile media. Non-volatile media includes, for example, optical or magnetic disks, such as storage device  610 . Volatile media includes dynamic memory, such as main memory  606 . Common forms of non-transitory media include, for example, a floppy disk, a flexible disk, hard disk, solid state drive, magnetic tape, or any other magnetic data storage medium, a CD-ROM, any other optical data storage medium, any physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, NVRAM, any other memory chip or cartridge, and networked versions of the same. 
     Non-transitory media is distinct from but may be used in conjunction with transmission media. Transmission media participates in transferring information between non-transitory media. For example, transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise bus  602 . Transmission media can also take the form of acoustic or light waves, such as those generated during radio-wave and infra-red data communications. 
     Various forms of media may be involved in carrying one or more sequences of one or more instructions to processor  604  for execution. For example, the instructions may initially be carried on a magnetic disk or solid state drive of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to computer system  600  can receive the data on the telephone line and use an infra-red transmitter to convert the data to an infra-red signal. An infra-red detector can receive the data carried in the infra-red signal and appropriate circuitry can place the data on bus  602 . Bus  602  carries the data to main memory  606 , from which processor  604  retrieves and executes the instructions. The instructions received by main memory  606  may retrieves and executes the instructions. The instructions received by main memory  606  may optionally be stored on storage device  610  either before or after execution by processor  604 . 
     The computer system  600  also includes a communication interface  618  coupled to bus  602 . Communication interface  618  provides a two-way data communication coupling to one or more network links that are connected to one or more local networks. For example, communication interface  618  may be an integrated services digital network (ISDN) card, cable modem, satellite modem, or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, communication interface  618  may be a local area network (LAN) card to provide a data communication connection to a compatible LAN (or WAN component to communicated with a WAN). Wireless links may also be implemented. In any such implementation, communication interface  618  sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information. 
     A network link typically provides data communication through one or more networks to other data devices. For example, a network link may provide a connection through local network to a host computer or to data equipment operated by an Internet Service Provider (ISP). The ISP in turn provides data communication services through the world wide packet data communication network now commonly referred to as the “Internet”. Local network and Internet both use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on network link and through communication interface  618 , which carry the digital data to and from computer system  600 , are example forms of transmission media. 
     The computer system  600  can send messages and receive data, including program code, through the network(s), network link and communication interface  618 . In the Internet example, a server might transmit a requested code for an application program through the Internet, the ISP, the local network and the communication interface  618 . 
     The received code may be executed by processor  604  as it is received, and/or stored in storage device  610 , or other non-volatile storage for later execution. 
     Each of the processes, methods, and algorithms described in the preceding sections may be embodied in, and fully or partially automated by, code modules executed by one or more computer systems or computer processors comprising computer hardware. The processes and algorithms may be implemented partially or wholly in application-specific circuitry. 
     The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of this disclosure. In addition, certain method or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described blocks or states may be performed in an order other than that specifically disclosed, or multiple blocks or states may be combined in a single block or state. The example blocks or states may be performed in serial, in parallel, or in some other manner. Blocks or states may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments. 
     Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. 
     Any process descriptions, elements, or blocks in the flow diagrams described herein and/or depicted in the attached figures should be understood as potentially representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps in the process. Alternate implementations are included within the scope of the embodiments described herein in which elements or functions may be deleted, executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those skilled in the art. 
     It should be emphasized that many variations and modifications may be made to the above-described embodiments, the elements of which are to be understood as being among other acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention can be practiced in many ways. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the invention with which that terminology is associated. The scope of the invention should therefore be construed in accordance with the appended claims and any equivalents thereof. 
     Engines, Components, and Logic 
     Certain embodiments are described herein as including logic or a number of components, engines, or mechanisms. Engines may constitute either software engines (e.g., code embodied on a machine-readable medium) or hardware engines. A “hardware engine” is a tangible unit capable of performing certain operations and may be configured or arranged in a certain physical manner. In various example embodiments, one or more computer systems (e.g., a standalone computer system, a client computer system, or a server computer system) or one or more hardware engines of a computer system (e.g., a processor or a group of processors) may be configured by software (e.g., an application or application portion) as a hardware engine that operates to perform certain operations as described herein. 
     In some embodiments, a hardware engine may be implemented mechanically, electronically, or any suitable combination thereof. For example, a hardware engine may include dedicated circuitry or logic that is permanently configured to perform certain operations. For example, a hardware engine may be a special-purpose processor, such as a Field-Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC). A hardware engine may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations. For example, a hardware engine may include software executed by a general-purpose processor or other programmable processor. Once configured by such software, hardware engines become specific machines (or specific components of a machine) uniquely tailored to perform the configured functions and are no longer general-purpose processors. It will be appreciated that the decision to implement a hardware engine mechanically, in dedicated and permanently configured circuitry, or in temporarily configured circuitry (e.g., configured by software) may be driven by cost and time considerations. 
     Accordingly, the phrase “hardware engine” should be understood to encompass a tangible entity, be that an entity that is physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein. As used herein, “hardware-implemented engine” refers to a hardware engine. Considering embodiments in which hardware engines are temporarily configured (e.g., programmed), each of the hardware engines need not be configured or instantiated at any one instance in time. For example, where a hardware engine comprises a general-purpose processor configured by software to become a special-purpose processor, the general-purpose processor may be configured as respectively different special-purpose processors (e.g., comprising different hardware engines) at different times. Software accordingly configures a particular processor or processors, for example, to constitute a particular hardware engine at one instance of time and to constitute a different hardware engine at a different instance of time. 
     Hardware engines can provide information to, and receive information from, other hardware engines. Accordingly, the described hardware engines may be regarded as being communicatively coupled. Where multiple hardware engines exist contemporaneously, communications may be achieved through signal transmission (e.g., over appropriate circuits and buses) between or among two or more of the hardware engines. In embodiments in which multiple hardware engines are configured or instantiated at different times, communications between such hardware engines may be achieved, for example, through the storage and retrieval of information in memory structures to which the multiple hardware engines have access. For example, one hardware engine may perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. A further hardware engine may then, at a later time, access the memory device to retrieve and process the stored output. Hardware engines may also initiate communications with input or output devices, and can operate on a resource (e.g., a collection of information). 
     The various operations of example methods described herein may be performed, at least partially, by one or more processors that are temporarily configured (e.g., by software) or permanently configured to perform the relevant operations. Whether temporarily or permanently configured, such processors may constitute processor-implemented engines that operate to perform one or more operations or functions described herein. As used herein, “processor-implemented engine” refers to a hardware engine implemented using one or more processors. 
     Similarly, the methods described herein may be at least partially processor-implemented, with a particular processor or processors being an example of hardware. For example, at least some of the operations of a method may be performed by one or more processors or processor-implemented engines. Moreover, the one or more processors may also operate to support performance of the relevant operations in a “cloud computing” environment or as a “software as a service” (SaaS). For example, at least some of the operations may be performed by a group of computers (as examples of machines including processors), with these operations being accessible via a network (e.g., the Internet) and via one or more appropriate interfaces (e.g., an Application Program Interface (API)). 
     The performance of certain of the operations may be distributed among the processors, not only residing within a single machine, but deployed across a number of machines. In some example embodiments, the processors or processor-implemented engines may be located in a single geographic location (e.g., within a home environment, an office environment, or a server farm). In other example embodiments, the processors or processor-implemented engines may be distributed across a number of geographic locations. 
     Language 
     Throughout this specification, plural instances may implement components, operations, or structures described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. Structures and functionality presented as separate components in example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of the subject matter herein. 
     Although an overview of the subject matter has been described with reference to specific example embodiments, various modifications and changes may be made to these embodiments without departing from the broader scope of embodiments of the present disclosure. Such embodiments of the subject matter may be referred to herein, individually or collectively, by the term “invention” merely for convenience and without intending to voluntarily limit the scope of this application to any single disclosure or concept if more than one is, in fact, disclosed. 
     The embodiments illustrated herein are described in sufficient detail to enable those skilled in the art to practice the teachings disclosed. Other embodiments may be used and derived therefrom, such that structural and logical substitutions and changes may be made without departing from the scope of this disclosure. The Detailed Description, therefore, is not to be taken in a limiting sense, and the scope of various embodiments is defined only by the appended claims, along with the full range of equivalents to which such claims are entitled. 
     It will be appreciated that an “engine,” “system,” “data store,” and/or “database” may comprise software, hardware, firmware, and/or circuitry. In one example, one or more software programs comprising instructions capable of being executable by a processor may perform one or more of the functions of the engines, data stores, databases, or systems described herein. In another example, circuitry may perform the same or similar functions. Alternative embodiments may comprise more, less, or functionally equivalent engines, systems, data stores, or databases, and still be within the scope of present embodiments. For example, the functionality of the various systems, engines, data stores, and/or databases may be combined or divided differently. 
     “Open source” software is defined herein to be source code that allows distribution as source code as well as compiled form, with a well-publicized and indexed means of obtaining the source, optionally with a license that allows modifications and derived works. 
     The data stores described herein may be any suitable structure (e.g., an active database, a relational database, a self-referential database, a table, a matrix, an array, a flat file, a documented-oriented storage system, a non-relational No-SQL system, and the like), and may be cloud-based or otherwise. 
     As used herein, the term “or” may be construed in either an inclusive or exclusive sense. Moreover, plural instances may be provided for resources, operations, or structures described herein as a single instance. Additionally, boundaries between various resources, operations, engines, and data stores are somewhat arbitrary, and particular operations are illustrated in a context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within a scope of various embodiments of the present disclosure. In general, structures and functionality presented as separate resources in the example configurations may be implemented as a combined structure or resource. Similarly, structures and functionality presented as a single resource may be implemented as separate resources. These and other variations, modifications, additions, and improvements fall within a scope of embodiments of the present disclosure as represented by the appended claims. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. 
     Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or steps. Thus, such conditional language is not generally intended to imply that features, elements and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements and/or steps are included or are to be performed in any particular embodiment. 
     Although the invention has been described in detail for the purpose of illustration based on what is currently considered to be the most practical and preferred implementations, it is to be understood that such detail is solely for that purpose and that the invention is not limited to the disclosed implementations, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. For example, it is to be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.