Patent Publication Number: US-2022214171-A1

Title: Passage planning and navigation systems and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and benefit of U.S. Provisional Patent Application No. 62/830,237 filed Apr. 5, 2019 and entitled “PASSAGE PLANNING SYSTEMS AND METHODS,” and U.S. Provisional Patent Application No. 62/830,259 filed Apr. 5, 2019 and entitled “PASSAGE NAVIGATION SYSTEMS AND METHODS,” which are hereby incorporated by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     One or more embodiments of the invention relate generally to passage planning and more particularly, for example, to systems and methods for substantially automated and environmentally compensated passage planning for mobile structures. 
     BACKGROUND 
     Some contemporary mobile structures, particularly vehicles with electrical propulsion systems, have limited ranges and difficulties associated with recharging their propulsion systems in areas outside their home berth. Range projection for such mobile structures can be dependent upon a wide array of different factors, including charge levels, environmental conditions (e.g., wind, current, sea state), desired traversal speed, availability of solar charging current, backup generator capacity, and/or other factors. Planning a passage or route for such mobile structures can be difficult, and inaccurate planning can result in unsafe situations and can convert such mobile structure into a navigational hazard for others. Thus, there is a need for a methodology that can accurately and reliably provide range projection for such mobile structures both when planning a passage or route and while traversing such planned route. 
     SUMMARY 
     Techniques are disclosed for systems and methods to provide passage planning for a mobile structure. In accordance with one or more embodiments, a passage planning system may include a logic device, a memory, one or more sensors, one or more actuators/controllers, and modules to interface with users, sensors, actuators, and/or other modules of a mobile structure. The logic device may be configured to determine an operational range map based, at least in part, on an operational state of the mobile structure and/or environmental conditions associated with the mobile structure. Such operational range map and other control signals may be displayed to a user and/or used to adjust a steering actuator, a propulsion system thrust, and/or other operational systems of the mobile structure. 
     In various embodiments, a passage planning system may include a user interface associated with a mobile structure and a logic device configured to communicate with the user interface and at least one operational state sensor mounted to or within the mobile structure. The user interface may include a display, and the logic device may be configured to determine an operational state of the mobile structure based, at least in part, on operational state data provided by the at least one operational state sensor; determine environmental conditions associated with the mobile structure; and determine an operational range map associated with the mobile structure based, at least in part, on the operational state of the mobile structure and the environmental conditions associated with the mobile structure. 
     In some embodiments, a method to provide passage planning for a mobile structure may include determining an operational state of a mobile structure based, at least in part, on operational state data provided by at least one operational state sensor mounted to or within the mobile structure; determining environmental conditions associated with the mobile structure; and determining an operational range map associated with the mobile structure based, at least in part, on the operational state of the mobile structure and the environmental conditions associated with the mobile structure. 
     In other embodiments, a passage planning system may include a logic device configured to communicate with a ranging sensor system mounted to a mobile structure. The logic device may be configured to aggregate ranging sensor data provided by the ranging sensor system into a passage database; determine a set of potential navigation hazard contacts based, at least in part, on the passage database; and determine a set of hazard priorities corresponding to the set of potential navigation hazard contacts based, at least in part, on the passage database. 
     In some embodiments, a method to provide passage planning for a mobile structure may include aggregating ranging sensor data provided by a ranging sensor system mounted to a mobile structure into a passage database; determining a set of potential navigation hazard contacts based, at least in part, on the passage database; and determining a set of hazard priorities corresponding to the set of potential navigation hazard contacts based, at least in part, on the passage database. 
     The scope of the invention is defined by the claims, which are incorporated into this section by reference. A more complete understanding of embodiments of the invention will be afforded to those skilled in the art, as well as a realization of additional advantages thereof, by a consideration of the following detailed description of one or more embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  illustrates a block diagram of a mobile structure including a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 1B  illustrates a diagram of a watercraft including a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 1C  illustrates a diagram of a steering sensor/actuator for a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 2  illustrates a diagram of an electric propulsion system for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 3  illustrates a diagram of an electric propulsion system for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 4  illustrates a graph of runtime and corresponding achievable linear range as a function of vessel speed for an electric propulsion system of a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 5  illustrates a polar comparator chart showing an estimated speed of a mobile structure with a passage planning system when provided motive force by electric power, wind, or a combination of wind and electrical power, in accordance with an embodiment of the disclosure. 
         FIG. 6  shows a display view including an operational range map for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIGS. 7-10  illustrate flow diagrams of control loops to provide passage planning in accordance with embodiments of the disclosure. 
         FIG. 11  illustrates a flow diagram of a process to provide range estimation and/or facilitate passage planning for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIGS. 12A-B  illustrate diagrams of an imaging system for use with a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 13  shows an augmented reality (AR) display view for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIGS. 14A-C  show AR display views for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 15  shows an image processing strategy for AR display views for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
         FIG. 16  illustrates a flow diagram of a process to provide AR display views for a mobile structure with a passage planning system in accordance with an embodiment of the disclosure. 
     
    
    
     Embodiments of the invention and their advantages are best understood by referring to the detailed description that follows. It should be appreciated that like reference numerals are used to identify like elements illustrated in one or more of the figures. 
     DETAILED DESCRIPTION 
     In accordance with various embodiments of the present disclosure, passage planning systems and methods may provide techniques for accurate and reliable range estimation and/or optimization for mobile structures, for example, to help navigate to a desired or safe destination within a safety margin (e.g., of fuel or battery storage) associated with the mobile structure and/or selected by a pilot of the mobile structure. When vessels have limited range (e.g., electric or electric assisted watercraft), the achievable range may be dependent upon many different and interrelated factors, such as battery storage, water current, wind, vessel speed, sea state, solar generating capability, gasoline generating capability, accessory power use, and/or other factors. Selecting a strategy to safely and reliably arrive at a destination can be a complex problem, and embodiments of system  100  may be configured to help users/pilots with passage planning and navigation according to a desired operational use of resources, as described herein. 
     In particular, for electric or electric assisted watercraft, such as a sailboat with backup electric propulsion, determining the safe range of possible travel can be very complex. For example, a sailboat travelling across 4 knots of wind may be able to make 2 knots under sail power alone, 6 knots under full 5 kW electric motor power, or 5 knots under sail by applying 750 W of electric motor power. In various embodiments, the electric motor can provide a ‘gearing’ effect where a small amount of electric power provides enough motive force to adjust the apparent wind to allow the sails to work more efficiently. For such assisted sailing or e-sailing system coupled with 10 kWh of storage, the achievable range can be transformed from approximately 12 Nm (e.g., using electric motor power alone) to 66 Nm by leveraging both electric and sail power while the electric power is available. 
     Other factors affecting range are wind direction and speed, water current, sea state, the effects of sea state on a particular vessel, desired residual battery charge, generating capacity such as solar (photovoltaic) panels or gas generator, accessory (e.g., cooler, navigation, ranging) usage, minimum speed limits and/or other traversal requirements (e.g., through shipping lanes), and/or other factors. For a pilot wanting to select a port of arrival and plan a reliable passage, there are typically too many factors to consider while attempting to navigate through traffic to a docking position. Thus, embodiments provide a graphical chart overlay or map to provide visualization of such operational range of a mobile structure that takes into account these factors and provides a reliable estimation of range, as described herein. Moreover, embodiments can use such operation range maps both to help plan a passage to a destination and to autopilot the mobile structure through such planned passage or route safely. 
       FIG. 1A  illustrates a block diagram of a passage planning system  100  in accordance with an embodiment of the disclosure. In various embodiments, system  100  may be adapted to provide STM sensor calibration for a particular mobile structure  101 . In some embodiments, system  100  may be adapted to measure an orientation, a position, and/or a velocity of mobile structure  101 . System  100  may then use these measurements to provide STM sensor calibration, which may then be used to control operation of mobile structure  101 , such as controlling elements of navigation control system  190  (e.g., steering actuator  150 , propulsion system  170 , and/or optional thrust maneuver system  172 ) to steer or orient mobile structure  101  according to a desired heading or orientation, such as heading angle  107 , for example. 
     In the embodiment shown in  FIG. 1A , system  100  may be implemented to provide STM sensor calibration for a particular type of mobile structure  101 , such as a drone, a watercraft, an aircraft, a robot, a vehicle, and/or other types of mobile structures. In one embodiment, system  100  may include one or more of a sonar system  110 , a user interface  120 , a controller  130 , an orientation sensor  140 , a speed sensor  142 , a gyroscope/accelerometer  144 , a global navigation satellite system (GNSS)  146 , a perimeter ranging system  148 , a steering sensor/actuator  150 , a propulsion system  170 , a thrust maneuver system  172 , and one or more other sensors and/or actuators used to sense and/or control a state of mobile structure  101 , such as other modules  180 . In some embodiments, one or more of the elements of system  100  may be implemented in a combined housing or structure that can be coupled to mobile structure  101  and/or held or carried by a user of mobile structure  101 . 
     Directions  102 ,  103 , and  104  describe one possible coordinate frame of mobile structure  101  (e.g., for headings or orientations measured by orientation sensor  140  and/or angular velocities and accelerations measured by gyroscope/accelerometer  144 ). As shown in  FIG. 1A , direction  102  illustrates a direction that may be substantially parallel to and/or aligned with a longitudinal axis of mobile structure  101 , direction  103  illustrates a direction that may be substantially parallel to and/or aligned with a lateral axis of mobile structure  101 , and direction  104  illustrates a direction that may be substantially parallel to and/or aligned with a vertical axis of mobile structure  101 , as described herein. For example, a roll component of motion of mobile structure  101  may correspond to rotations around direction  102 , a pitch component may correspond to rotations around direction  103 , and a yaw component may correspond to rotations around direction  104 . 
     Heading angle  107  may correspond to the angle between a projection of a reference direction  106  (e.g., the local component of the Earth&#39;s magnetic field) onto a horizontal plane (e.g., referenced to a gravitationally defined “down” vector local to mobile structure  101 ) and a projection of direction  102  onto the same horizontal plane. In some embodiments, the projection of reference direction  106  onto a horizontal plane (e.g., referenced to a gravitationally defined “down” vector) may be referred to as Magnetic North. In various embodiments, Magnetic North, a “down” vector, and/or various other directions, positions, and/or fixed or relative reference frames may define an absolute coordinate frame, for example, where directional measurements referenced to an absolute coordinate frame may be referred to as absolute directional measurements (e.g., an “absolute” orientation). 
     In some embodiments, directional measurements may initially be referenced to a coordinate frame of a particular sensor (e.g., a sonar transducer assembly or module of sonar system  110 ) and be transformed (e.g., using parameters for one or more coordinate frame transformations) to be referenced to an absolute coordinate frame and/or a coordinate frame of mobile structure  101 . In various embodiments, an absolute coordinate frame may be defined and/or correspond to a coordinate frame with one or more undefined axes, such as a horizontal plane local to mobile structure  101  referenced to a local gravitational vector but with an unreferenced and/or undefined yaw reference (e.g., no reference to Magnetic North). 
     Sonar system  110  may be implemented with one or more electrically and/or mechanically coupled controllers, transmitters, receivers, transceivers, signal processing logic devices, autonomous power systems, various electrical components, transducer elements of various shapes and sizes, multichannel transducers/transducer modules, transducer assemblies, assembly brackets, transom brackets, and/or various actuators adapted to adjust orientations of any of the components of sonar system  110 , as described herein. Sonar system  110  may be configured to emit one, multiple, or a series of acoustic beams, receive corresponding acoustic returns, and convert the acoustic returns into sonar data and/or imagery, such as bathymetric data, water depth, water temperature, water column/volume debris, bottom profile, and/or other types of sonar data. Sonar system  110  may be configured to provide such data and/or imagery to user interface  120  for display to a user, for example, or to controller  130  for additional processing, as described herein. 
     For example, in various embodiments, sonar system  110  may be implemented and/or operated according to any one or combination of the systems and methods described in U.S. Provisional Patent Application 62/005,838 filed May 30, 2014 and entitled “MULTICHANNEL SONAR SYSTEMS AND METHODS”, U.S. Provisional Patent Application 61/943,170 filed Feb. 21, 2014 and entitled “MODULAR SONAR TRANSDUCER ASSEMBLY SYSTEMS AND METHODS”, and/or U.S. Provisional Patent Application 62/087,189 filed Dec. 3, 2014 and entitled “AUTONOMOUS SONAR SYSTEMS AND METHODS”, each of which are hereby incorporated by reference in their entirety. In other embodiments, sonar system  110  may be implemented according to other sonar system arrangements that can be used to detect objects within a water column and/or a floor of a body of water. 
     User interface  120  may be implemented as one or more of a display, a touch screen, a keyboard, a mouse, a joystick, a knob, a steering wheel, a ship&#39;s wheel or helm, a yoke, and/or any other device capable of accepting user input and/or providing feedback to a user. For example, in some embodiments, user interface  120  may be implemented and/or operated according to any one or combination of the systems and methods described in U.S. Provisional Patent Application 62/069,961 filed Oct. 29, 2014 and entitled “PILOT DISPLAY SYSTEMS AND METHODS”, which is hereby incorporated by reference in its entirety. 
     In various embodiments, user interface  120  may be adapted to provide user input (e.g., as a type of signal and/or sensor information) to other devices of system  100 , such as controller  130 . User interface  120  may also be implemented with one or more logic devices that may be adapted to execute instructions, such as software instructions, implementing any of the various processes and/or methods described herein. For example, user interface  120  may be adapted to form communication links, transmit and/or receive communications (e.g., sensor signals, control signals, sensor information, user input, and/or other information), determine various coordinate frames and/or orientations, determine parameters for one or more coordinate frame transformations, and/or perform coordinate frame transformations, for example, or to perform various other processes and/or methods described herein. 
     In some embodiments, user interface  120  may be adapted to accept user input, for example, to form a communication link, to select a particular wireless networking protocol and/or parameters for a particular wireless networking protocol and/or wireless link (e.g., a password, an encryption key, a MAC address, a device identification number, a device operation profile, parameters for operation of a device, and/or other parameters), to select a method of processing sensor signals to determine sensor information, to adjust a position and/or orientation of an articulated sensor, and/or to otherwise facilitate operation of system  100  and devices within system  100 . Once user interface  120  accepts a user input, the user input may be transmitted to other devices of system  100  over one or more communication links. 
     In one embodiment, user interface  120  may be adapted to receive a sensor or control signal (e.g., from orientation sensor  140  and/or steering sensor/actuator  150 ) over communication links formed by one or more associated logic devices, for example, and display sensor and/or other information corresponding to the received sensor or control signal to a user. In related embodiments, user interface  120  may be adapted to process sensor and/or control signals to determine sensor and/or other information. For example, a sensor signal may include an orientation, an angular velocity, an acceleration, a speed, and/or a position of mobile structure  101  and/or other elements of system  100 . In such embodiments, user interface  120  may be adapted to process the sensor signals to determine sensor information indicating an estimated and/or absolute roll, pitch, and/or yaw (attitude and/or rate), and/or a position or series of positions of mobile structure  101  and/or other elements of system  100 , for example, and display the sensor information as feedback to a user. 
     In one embodiment, user interface  120  may be adapted to display a time series of various sensor information and/or other parameters as part of or overlaid on a graph or map, which may be referenced to a position and/or orientation of mobile structure  101  and/or other element of system  100 . For example, user interface  120  may be adapted to display a time series of positions, headings, and/or orientations of mobile structure  101  and/or other elements of system  100  overlaid on a geographical map, which may include one or more graphs indicating a corresponding time series of actuator control signals, sensor information, and/or other sensor and/or control signals. 
     In some embodiments, user interface  120  may be adapted to accept user input including a user-defined target heading, waypoint, route, and/or orientation for an element of system  100 , for example, and to generate control signals for navigation control system  190  to cause mobile structure  101  to move according to the target heading, waypoint, route, track, and/or orientation. In other embodiments, user interface  120  may be adapted to accept user input modifying a control loop parameter of controller  130 , for example, or selecting a responsiveness of controller  130  in controlling a direction (e.g., through application of a particular steering angle) of mobile structure  101 . 
     For example, a responsiveness setting may include selections of Performance (e.g., fast response), Cruising (medium response), Economy (slow response), and Docking responsiveness, where the different settings are used to choose between a more pronounced and immediate steering response (e.g., a faster control loop response) or reduced steering actuator activity (e.g., a slower control loop response). In some embodiments, a responsiveness setting may correspond to a maximum desired lateral acceleration during a turn. In such embodiments, the responsiveness setting may modify a gain, a deadband, a limit on an output, a bandwidth of a filter, and/or other control loop parameters of controller  130 , as described herein. 
     In further embodiments, user interface  120  may be adapted to accept user input including a user-defined target attitude, orientation, and/or position for an actuated device (e.g., sonar system  110 ) associated with mobile structure  101 , for example, and to generate control signals for adjusting an orientation and/or position of the actuated device according to the target attitude, orientation, and/or position. More generally, user interface  120  may be adapted to display sensor information to a user, for example, and/or to transmit sensor information and/or user input to other user interfaces, sensors, or controllers of system  100 , for instance, for display and/or further processing. 
     Controller  130  may be implemented as any appropriate logic device (e.g., processing device, microcontroller, processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), memory storage device, memory reader, or other device or combinations of devices) that may be adapted to execute, store, and/or receive appropriate instructions, such as software instructions implementing a control loop for controlling various operations of navigation control system  190 , mobile structure  101 , and/or other elements of system  100 , for example. Such software instructions may also implement methods for processing sensor signals, determining sensor information, providing user feedback (e.g., through user interface  120 ), querying devices for operational parameters, selecting operational parameters for devices, or performing any of the various operations described herein (e.g., operations performed by logic devices of various devices of system  100 ). 
     In addition, a machine readable medium may be provided for storing non-transitory instructions for loading into and execution by controller  130 . In these and other embodiments, controller  130  may be implemented with other components where appropriate, such as volatile memory, non-volatile memory, one or more interfaces, and/or various analog and/or digital components for interfacing with devices of system  100 . For example, controller  130  may be adapted to store sensor signals, sensor information, parameters for coordinate frame transformations, calibration parameters, sets of calibration points, and/or other operational parameters, over time, for example, and provide such stored data to a user using user interface  120 . In some embodiments, controller  130  may be integrated with one or more user interfaces (e.g., user interface  120 ) and/or may share a communication module or modules. 
     As noted herein, controller  130  may be adapted to execute one or more control loops to model or provide device control, steering control (e.g., using navigation control system  190 ) and/or performing other various operations of mobile structure  101  and/or system  100 . In some embodiments, a control loop may include processing sensor signals and/or sensor information in order to control one or more operations of mobile structure  101  and/or system  100 . 
     For example, controller  130  may be adapted to receive a measured heading  107  of mobile structure  101  from orientation sensor  140 , a measured steering rate (e.g., a measured yaw rate, in some embodiments) from gyroscope/accelerometer  144 , a measured speed from speed sensor  142 , a measured position or series of absolute and/or relative positions from GNSS  146 , a measured steering angle from steering sensor/actuator  150 , perimeter sensor data from perimeter ranging system  148 , and/or a user input from user interface  120 . In some embodiments, a user input may include a target heading  106 , for example, an absolute position and/or waypoint (e.g., from which target heading  106  may be derived), and/or one or more other control loop parameters. In further embodiments, controller  130  may be adapted to determine a steering demand or other control signal for navigation control system  190  based on one or more of the received sensor signals, including the user input, and provide the steering demand/control signal to steering sensor/actuator  150  and/or navigation control system  190 . 
     In some embodiments, a control loop may include a nominal vehicle predictor used to produce a feedback signal corresponding to an average or nominal vehicle/mobile structure rather than one specific to mobile structure  101 . Such feedback signal may be used to adjust or correct control signals, as described herein. In some embodiments, a control loop may include one or more vehicle dynamics modules corresponding to actual vehicles, for example, that may be used to implement an adaptive algorithm for training various control loop parameters, such as parameters for a nominal vehicle predictor, without necessitating real-time control of an actual mobile structure. 
     Orientation sensor  140  may be implemented as one or more of a compass, float, accelerometer, and/or other device capable of measuring an orientation of mobile structure  101  (e.g., magnitude and direction of roll, pitch, and/or yaw, relative to one or more reference orientations such as gravity and/or Magnetic North) and providing such measurements as sensor signals that may be communicated to various devices of system  100 . In some embodiments, orientation sensor  140  may be adapted to provide heading measurements for mobile structure  101 . In other embodiments, orientation sensor  140  may be adapted to provide a pitch, pitch rate, roll, roll rate, yaw, and/or yaw rate for mobile structure  101  (e.g., using a time series of orientation measurements). In such embodiments, controller  130  may be configured to determine a compensated yaw rate based on the provided sensor signals. In various embodiments, a yaw rate and/or compensated yaw rate may be approximately equal to a steering rate of mobile structure  101 . Orientation sensor  140  may be positioned and/or adapted to make orientation measurements in relation to a particular coordinate frame of mobile structure  101 , for example. 
     Speed sensor  142  may be implemented as an electronic pitot tube, metered gear or wheel, water speed sensor, wind speed sensor, a wind velocity sensor (e.g., direction and magnitude) and/or other device capable of measuring or determining a linear speed of mobile structure  101  (e.g., in a surrounding medium and/or aligned with a longitudinal axis of mobile structure  101 ) and providing such measurements as sensor signals that may be communicated to various devices of system  100 . In some embodiments, speed sensor  142  may be adapted to provide a velocity of a surrounding medium relative to sensor  142  and/or mobile structure  101 . For example, speed sensor  142  may be configured to provide an absolute or relative wind velocity or water velocity impacting mobile structure  101 . In various embodiments, system  100  may include multiple embodiments of speed sensor  142 , such as one wind velocity sensor and one water velocity sensor. In various embodiments, speed sensor  142  may be referred to as an STM sensor. 
     Gyroscope/accelerometer  144  may be implemented as one or more electronic sextants, semiconductor devices, integrated chips, accelerometer sensors, accelerometer sensor systems, or other devices capable of measuring angular velocities/accelerations and/or linear accelerations (e.g., direction and magnitude) of mobile structure  101  and providing such measurements as sensor signals that may be communicated to other devices of system  100  (e.g., user interface  120 , controller  130 ). In some embodiments, gyroscope/accelerometer  144  may be adapted to determine pitch, pitch rate, roll, roll rate, yaw, yaw rate, compensated yaw rate, an absolute speed, and/or a linear acceleration rate of mobile structure  101 . Thus, gyroscope/accelerometer  144  may be adapted to provide a measured heading, a measured steering rate, and/or a measured speed for mobile structure  101 . In some embodiments, gyroscope/accelerometer  144  may provide pitch rate, roll rate, yaw rate, and/or a linear acceleration of mobile structure  101  to controller  130  and controller  130  may be adapted to determine a compensated yaw rate based on the provided sensor signals. Gyroscope/accelerometer  144  may be positioned and/or adapted to make such measurements in relation to a particular coordinate frame of mobile structure  101 , for example. In various embodiments, gyroscope/accelerometer  144  may be implemented in a common housing and/or module to ensure a common reference frame or a known transformation between reference frames. 
     GNSS  146  may be implemented as a global positioning satellite receiver and/or other device capable of determining an absolute and/or relative position of mobile structure  101  based on wireless signals received from space-born and/or terrestrial sources, for example, and capable of providing such measurements as sensor signals that may be communicated to various devices of system  100 . In some embodiments, GNSS  146  may be adapted to determine and/or estimate a velocity, speed, and/or yaw rate of mobile structure  101  (e.g., using a time series of position measurements), such as an absolute velocity and/or a yaw component of an angular velocity of mobile structure  101 . In various embodiments, one or more logic devices of system  100  may be adapted to determine a calculated speed of mobile structure  101  and/or a computed yaw component of the angular velocity from such sensor information. GNSS  146  may also be used to estimate a relative wind velocity or a water current velocity, for example, using a time series of position measurements while mobile structure is otherwise lacking powered navigation control. 
     Perimeter ranging system  148  may be adapted to detect navigation hazards within a monitoring perimeter of mobile structure  101  (e.g., within a preselected or predetermined range of a perimeter of mobile structure  101 ) and measure ranges to the detected navigation hazards (e.g., the closest approach distance between a perimeter of mobile structure  101  and a detected navigation hazard) and/or relative velocities of the detected navigation hazards. In some embodiments, perimeter ranging system  148  may be implemented by one or more ultrasonic sensor arrays distributed along the perimeter of mobile structure  101 , radar systems, short range radar systems (e.g., including radar arrays configured to detect and/or range objects between a few centimeters and 10s of meters from a perimeter of mobile structure  101 ), visible spectrum and/or infrared/thermal imaging modules or cameras, stereo cameras, LIDAR systems, combinations of these, and/or other perimeter ranging systems configured to provide relatively fast and accurate perimeter sensor data (e.g., so as to accommodate suddenly changing navigation conditions due to external disturbances such as tide and wind loadings on mobile structure  101 ). 
     Navigation hazards, as used herein, may include an approaching dock or tie down post, other vehicles, floating debris, mooring lines, swimmers or water life, and/or other navigation hazards large and/or solid enough to damage mobile structure  101 , for example, or that require their own safety perimeter due to regulation, safety, or other concerns. As such, in some embodiments, perimeter ranging system  148  and/or controller  130  may be configured to differentiate types of navigation hazards and/or objects or conditions that do not present a navigation hazard, such as seaweed, pollution slicks, relatively small floating debris (e.g., depending on a relative speed of the floating debris), and/or other non-hazardous but detectable objects. 
     Steering sensor/actuator  150  may be adapted to physically adjust a heading of mobile structure  101  according to one or more control signals, user inputs, and/or stabilized attitude estimates provided by a logic device of system  100 , such as controller  130 . Steering sensor/actuator  150  may include one or more actuators and control surfaces (e.g., a rudder or other type of steering mechanism) of mobile structure  101 , and may be adapted to sense and/or physically adjust the control surfaces to a variety of positive and/or negative steering angles/positions. 
     For example,  FIG. 1C  illustrates a diagram of a steering sensor/actuator for a passage planning system in accordance with an embodiment of the disclosure. As shown in  FIG. 1C , rear portion  101 C of mobile structure  101  includes steering sensor/actuator  150  configured to sense a steering angle of rudder  152  and/or to physically adjust rudder  152  to a variety of positive and/or negative steering angles, such as a positive steering angle α measured relative to a zero steering angle direction (e.g., designated by a dashed line  134 ). In various embodiments, steering sensor/actuator  150  may be implemented with a steering actuator angle limit (e.g., the positive limit is designated by an angle β and a dashed line  136  in  FIG. 1C ), and/or a steering actuator rate limit “R”. 
     As described herein, a steering actuator rate limit may be a limit of how quickly steering sensor/actuator  150  can change a steering angle of a steering mechanism (e.g., rudder  132 ), and, in some embodiments, such steering actuator rate limit may vary depending on a speed of mobile structure  101  along heading  104  (e.g., a speed of a ship relative to surrounding water, or of a plane relative to a surrounding air mass). In further embodiments, a steering actuator rate limit may vary depending on whether steering sensor/actuator  150  is turning with (e.g., an increased steering actuator rate limit) or turning against (e.g., a decreased steering actuator rate limit) a prevailing counteracting force, such as a prevailing current (e.g., a water and/or air current). A prevailing current may be determined from sensor signals provided by orientation sensor  140 , gyroscope/accelerometer  142 , speed sensor  144 , and/or GNSS  146 , for example. 
     In various embodiments, steering sensor/actuator  150  may be implemented as a number of separate sensors and/or actuators, for example, to sense and/or control one or more steering mechanisms substantially simultaneously, such as one or more rudders, elevators, and/or automobile steering mechanisms, for example. In some embodiments, steering sensor/actuator  150  may include one or more sensors and/or actuators adapted to sense and/or adjust a propulsion force (e.g., a propeller speed and/or an engine rpm) of mobile structure  101 , for example, to effect a particular navigation maneuver (e.g., to meet a particular steering demand within a particular period of time), for instance, or to provide a safety measure (e.g., an engine cut-off and/or reduction in mobile structure speed). 
     In some embodiments, rudder  152  (e.g., a steering mechanism) may be implemented as one or more control surfaces and/or conventional rudders, one or more directional propellers and/or vector thrusters (e.g., directional water jets), a system of fixed propellers and/or thrusters that can be powered at different levels and/or reversed to effect a steering rate of mobile structure  101 , and/or other types or combination of types of steering mechanisms appropriate for mobile structure  101 . In embodiments where rudder  152  is implemented, at least in part, as a system of fixed propellers and/or thrusters, steering angle α may represent an effective and/or expected steering angle based on, for example, characteristics of mobile structure  101 , the system of fixed propellers and/or thrusters (e.g., their position on mobile structure  101 ), and/or control signals provided to steering sensor/actuator  150 . An effective and/or expected steering angle α may be determined by controller  130  according to a pre-determined algorithm, for example, or through use of an adaptive algorithm for training various control loop parameters characterizing the relationship of steering angle α to, for instance, power levels provided to the system of fixed propellers and/or thrusters and/or control signals provided by controller  130 , as described herein. 
     Propulsion system  170  may be implemented as a propeller, turbine, or other thrust-based propulsion system, a mechanical wheeled and/or tracked propulsion system, a sail-based propulsion system, and/or other types of propulsion systems that can be used to provide motive force to mobile structure  101 . In some embodiments, propulsion system  170  may be non-articulated, for example, such that the direction of motive force and/or thrust generated by propulsion system  170  is fixed relative to a coordinate frame of mobile structure  101 . Non-limiting examples of non-articulated propulsion systems include, for example, an inboard motor for a watercraft with a fixed thrust vector, for example, or a fixed aircraft propeller or turbine. In other embodiments, propulsion system  170  may be articulated, for example, and/or may be coupled to and/or integrated with steering sensor/actuator  150 , such that the direction of generated motive force and/or thrust is variable relative to a coordinate frame of mobile structure  101 . Non-limiting examples of articulated propulsion systems include, for example, an outboard motor for a watercraft, an inboard motor for a watercraft with a variable thrust vector/port (e.g., used to steer the watercraft), a sail, or an aircraft propeller or turbine with a variable thrust vector, for example. As such, in some embodiments, propulsion system  170  may be integrated with steering sensor/actuator  150 . 
     Optional thrust maneuver system  172  may be adapted to physically adjust a position, orientation, and/or linear and/or angular velocity of mobile structure  101  according to one or more control signals and/or user inputs provided by a logic device of system  100 , such as controller  130 . Thrust maneuver system  172  may be implemented as one or more directional propellers and/or vector thrusters (e.g., directional water jets), and/or a system of fixed propellers and/or thrusters coupled to mobile structure  101  that can be powered at different levels and/or reversed to maneuver mobile structure  101  according to a desired linear and/or angular velocity. 
     Other modules  180  may include other and/or additional sensors, actuators, communications modules/nodes, and/or user interface devices used to provide additional environmental information of mobile structure  101 , for example. In some embodiments, other modules  180  may include a humidity sensor, a wind and/or water temperature sensor, a barometer, a radar system, a visible spectrum camera, an infrared camera, and/or other environmental sensors providing measurements and/or other sensor signals that can be displayed to a user and/or used by other devices of system  100  (e.g., controller  130 ) to provide operational control of mobile structure  101  and/or system  100  that compensates for environmental conditions, such as wind speed and/or direction, swell speed, amplitude, and/or direction, and/or an object in a path of mobile structure  101 , for example. In some embodiments, other modules  180  may include one or more actuated and/or articulated devices (e.g., spotlights, visible and/or IR cameras, radars, sonars, and/or other actuated devices) coupled to mobile structure  101 , where each actuated device includes one or more actuators adapted to adjust an orientation of the device, relative to mobile structure  101 , in response to one or more control signals (e.g., provided by controller  130 ). 
     In general, each of the elements of system  100  may be implemented with any appropriate logic device (e.g., processing device, microcontroller, processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), memory storage device, memory reader, or other device or combinations of devices) that may be adapted to execute, store, and/or receive appropriate instructions, such as software instructions implementing any of the methods described herein, for example, including for transmitting and/or receiving communications, such as sensor signals, sensor information, and/or control signals, between one or more devices of system  100 . In various embodiments, such method may include instructions for forming one or more communication links between various devices of system  100 . 
     In addition, one or more machine readable mediums may be provided for storing non-transitory instructions for loading into and execution by any logic device implemented with one or more of the devices of system  100 . In these and other embodiments, the logic devices may be implemented with other components where appropriate, such as volatile memory, non-volatile memory, and/or one or more interfaces (e.g., inter-integrated circuit (I2C) interfaces, mobile industry processor interfaces (MIPI), joint test action group (JTAG) interfaces (e.g., IEEE 1149.1 standard test access port and boundary-scan architecture), controller area network (CAN) bus interfaces, and/or other interfaces, such as an interface for one or more antennas, or an interface for a particular type of sensor). 
     Each of the elements of system  100  may be implemented with one or more amplifiers, modulators, phase adjusters, beamforming components, digital to analog converters (DACs), analog to digital converters (ADCs), various interfaces, antennas, transducers, and/or other analog and/or digital components enabling each of the devices of system  100  to transmit and/or receive signals, for example, in order to facilitate wired and/or wireless communications between one or more devices of system  100 . Such components may be integrated with a corresponding element of system  100 , for example. In some embodiments, the same or similar components may be used to perform one or more sensor measurements, as described herein. 
     Sensor signals, control signals, and other signals may be communicated among elements of system  100  using a variety of wired and/or wireless communication techniques, including voltage signaling, Ethernet, WiFi, Bluetooth, Zigbee, Xbee, Micronet, CAN bus, or other medium and/or short range wired and/or wireless networking protocols and/or implementations, for example. In such embodiments, each element of system  100  may include one or more modules supporting wired, wireless, and/or a combination of wired and wireless communication techniques. 
     In some embodiments, various elements or portions of elements of system  100  may be integrated with each other, for example, or may be integrated onto a single printed circuit board (PCB) to reduce system complexity, manufacturing costs, power requirements, coordinate frame errors, and/or timing errors between the various sensor measurements. For example, gyroscope/accelerometer  144  and controller  130  may be configured to share one or more components, such as a memory, a logic device, a communications module, and/or other components, and such sharing may act to reduce and/or substantially eliminate such timing errors while reducing overall system complexity and/or cost. 
     Each element of system  100  may include one or more batteries, capacitors, or other electrical power storage devices, for example, and may include one or more solar cell modules or other electrical power generating devices (e.g., a wind or water-powered turbine, or a generator producing electrical power from motion of one or more elements of system  100 ). In some embodiments, one or more of the devices may be powered by a power source for mobile structure  101 , using one or more power leads. Such power leads may also be used to support one or more communication techniques between elements of system  100 . 
     In various embodiments, a logic device of system  100  (e.g., of orientation sensor  140  and/or other elements of system  100 ) may be adapted to determine parameters (e.g., using signals from various devices of system  100 ) for transforming a coordinate frame of other elements of system  100  to/from a coordinate frame of mobile structure  101 , at-rest and/or in-motion, and/or other coordinate frames, as described herein. One or more logic devices of system  100  may be adapted to use such parameters to transform a coordinate frame of the other elements of system  100  to/from a coordinate frame of orientation sensor  140  and/or mobile structure  101 , for example. Furthermore, such parameters may be used to determine and/or calculate one or more adjustments to an orientation of an element of system  100  that would be necessary to physically align a coordinate frame of the element with a coordinate frame of orientation sensor  140  and/or mobile structure  101 , for example, or an absolute coordinate frame and/or other desired positions and/or orientations. Adjustments determined from such parameters may be used to selectively power adjustment servos/actuators (e.g., of various elements of system  100 ), for example, or may be communicated to a user through user interface  120 , as described herein. 
       FIG. 1B  illustrates a diagram of system  100 B in accordance with an embodiment of the disclosure. In the embodiment shown in  FIG. 1B , system  100 B may be implemented to provide STM sensor calibration and/or additional operational control of mobile structure  101 , similar to system  100  of  FIG. 1B . For example, system  100 B may include integrated user interface/controller  120 / 130 , secondary user interface  120 , perimeter ranging system  148   a  and  148   b , steering sensor/actuator  150 , sensor cluster  160  (e.g., orientation sensor  140 , gyroscope/accelerometer  144 , and/or GNSS  146 ), and various other sensors and/or actuators. In the embodiment illustrated by  FIG. 1B , mobile structure  101  is implemented as a motorized boat including a hull  105   b , a deck  106   b , a transom  107   b , a mast/sensor mount  108   b , a rudder  152 , an inboard motor  170 , articulated thrust maneuver jet  172 , an actuated sonar system  110  coupled to transom  107   b , perimeter ranging system  148   a  (e.g., a camera system, radar system, and/or LIDAR system) coupled to mast/sensor mount  108   b , optionally through roll, pitch, and/or yaw actuator  162 , and perimeter ranging system  148   b  (e.g., an ultrasonic sensor array and/or short range radar system)) coupled to hull  105   b  or deck  106   b  substantially above a water line of mobile structure  101 . In other embodiments, hull  105   b , deck  106   b , mast/sensor mount  108   b , rudder  152 , inboard motor  170 , and various actuated devices may correspond to attributes of a passenger aircraft or other type of vehicle, robot, or drone, for example, such as an undercarriage, a passenger compartment, an engine/engine compartment, a trunk, a roof, a steering mechanism, a headlight, a radar system, and/or other portions of a vehicle. 
     As depicted in  FIG. 1B , mobile structure  101  includes actuated sonar system  110 , which in turn includes transducer assembly  112  coupled to transom  107   b  of mobile structure  101  through assembly bracket/actuator  116  and transom bracket/electrical conduit  114 . In some embodiments, assembly bracket/actuator  116  may be implemented as a roll, pitch, and/or yaw actuator, for example, and may be adapted to adjust an orientation of transducer assembly  112  according to control signals and/or an orientation (e.g., roll, pitch, and/or yaw) or position of mobile structure  101  provided by user interface/controller  120 / 130 . Similarly, actuator  162  may be adapted to adjust an orientation of perimeter ranging system  148  according to control signals and/or an orientation or position of mobile structure  101  provided by user interface/controller  120 / 130 . For example, user interface/controller  120 / 130  may be adapted to receive an orientation of transducer assembly  112  and/or perimeter ranging system  148  (e.g., from sensors embedded within the assembly or device), and to adjust an orientation of either to maintain sensing/illuminating a position and/or absolute direction in response to motion of mobile structure  101 , using one or more orientations and/or positions of mobile structure  101  and/or other sensor information derived by executing various methods described herein. 
     In one embodiment, user interfaces  120  may be mounted to mobile structure  101  substantially on deck  106   b  and/or mast/sensor mount  108   b . Such mounts may be fixed, for example, or may include gimbals and other leveling mechanisms/actuators so that a display of user interfaces  120  stays substantially level with respect to a horizon and/or a “down” vector (e.g., to mimic typical user head motion/orientation). In another embodiment, at least one of user interfaces  120  may be located in proximity to mobile structure  101  and be mobile throughout a user level (e.g., deck  106   b ) of mobile structure  101 . For example, secondary user interface  120  may be implemented with a lanyard and/or other type of strap and/or attachment device and be physically coupled to a user of mobile structure  101  so as to be in proximity to mobile structure  101 . In various embodiments, user interfaces  120  may be implemented with a relatively thin display that is integrated into a PCB of the corresponding user interface in order to reduce size, weight, housing complexity, and/or manufacturing costs. 
     As shown in  FIG. 1B , in some embodiments, speed sensor  142  may be mounted to a portion of mobile structure  101 , such as to hull  105   b , and be adapted to measure a relative water speed, such as a STM or STW sensor configured to measure the relative speed of mobile structure  101  through a surrounding water medium, substantially along longitudinal axis  102 . In some embodiments, speed sensor  142  may be adapted to provide a relatively thin profile to reduce and/or avoid water drag. In various embodiments, speed sensor  142  may be mounted to a portion of mobile structure  101  that is substantially outside easy operational accessibility. Speed sensor  142  may include one or more batteries and/or other electrical power storage devices, for example, and may include one or more water-powered turbines to generate electrical power. In other embodiments, speed sensor  142  may be powered by a power source for mobile structure  101 , for example, using one or more power leads penetrating hull  105   b . In alternative embodiments, speed sensor  142  may be implemented as a wind velocity sensor, for example, and may be mounted to mast/sensor mount  108   b  to have relatively clear access to local wind. 
     In the embodiment illustrated by  FIG. 1B , mobile structure  101  includes direction/longitudinal axis  102 , direction/lateral axis  103 , and direction/vertical axis  104  meeting approximately at mast/sensor mount  108   b  (e.g., near a center of gravity of mobile structure  101 ). In one embodiment, the various axes may define a coordinate frame of mobile structure  101  and/or sensor cluster  160 . Each sensor adapted to measure a direction (e.g., velocities, accelerations, headings, or other states including a directional component) may be implemented with a mount, actuators, and/or servos that can be used to align a coordinate frame of the sensor with a coordinate frame of any element of system  100 B and/or mobile structure  101 . Each element of system  100 B may be located at positions different from those depicted in  FIG. 1B . Each device of system  100 B may include one or more batteries or other electrical power storage devices, for example, and may include one or more solar cell modules or other electrical power generating devices. In some embodiments, one or more of the devices may be powered by a power source for mobile structure  101 . As noted herein, each element of system  100 B may be implemented with an antenna, a logic device, and/or other analog and/or digital components enabling that element to provide, receive, and process sensor signals and interface or communicate with one or more devices of system  100 B. Further, a logic device of that element may be adapted to perform any of the methods described herein. 
       FIG. 2  illustrates a diagram of an electric propulsion system  200  for mobile structure  101  with elements of passage planning system  100  of  FIGS. 1A-B , which may be implemented as an embodiment of propulsion system  170  and/or other elements of navigation system  190  of  FIG. 1A . In particular, as shown in  FIG. 2 , electric propulsion system  200  may include a shore power coupling/converter  210  receiving external power  209  from a shore or dock hookup and providing external charging power  211  to main battery  220 , which may be used to store and deliver mechanical propulsion power  221  to electric drive motor  230  to provide propulsive force to mobile structure  101  (e.g., through a propeller or other thrust system, as described herein). Electric propulsion system  200  may also include fuel tank  240  providing fuel according to fuel consumption  241  to combustion (e.g., diesel, gasoline) generator  242 , which may be configured to provide generator charging power  243  to charge main battery  220  and/or power electric drive motor  230 . 
     In some embodiments, electric propulsion system  200  may additionally or alternatively include solar panels  250  providing solar charging power  251  to leveling or ballast battery bank  252 , which may be configured to provide or receive exchange power  253  to charge main battery  220  and/or help level charge across multiple cells within main battery  220 . As shown in  FIG. 2 , electric propulsion system  200  may also include an accessory power sink  224 , such as a cooler or fridge, for example, or an electronic navigation system (e.g., including elements of system  100  of  FIG. 1A ), that draws or consumes accessory power  222  from main battery  220 . Electric propulsion system  200  may include a separate accessory battery  260  (e.g., used to start generator  242  and/or provide emergency power if main battery  220  is exhausted or damaged) and/or a communications module  270  (e.g., to communicate to other vessels or shore-based systems, including remote storage systems, as described herein). 
     Each of the elements of electric propulsion system  200  may be implemented with power (e.g., voltage and/or current) monitoring and/or switching circuitry to allow controller  130  of system  100 , for example, to monitor and/or control power delivery to elements of electric propulsion system  200 . Moreover, main battery  220 , leveling battery bank  252 , and accessory battery  260  may be implemented with charge state monitoring circuitry to allow controller  130  to monitor the various charge states of each battery. In various embodiments, controller  130  may be configured to receive an electrical status of electric propulsion system  200 , including power delivery and/or charge state of each of the elements of electric propulsion system  200 , and to determine an electric propulsion state of electric propulsion system  200  based on such status. Such electric propulsion state (e.g., an operational state of mobile structure  101 ) may be used, along with other factors, to determine an achievable range of mobile structure  101 , as described herein. 
       FIG. 3  illustrates a diagram of an electric propulsion system  300  for mobile structure  101  with elements of passage planning system  100  of  FIGS. 1A-B , which may be implemented as an embodiment of propulsion system  170  and/or other elements of navigation system  190  of  FIG. 1A . In particular, as shown in  FIG. 3 , electric propulsion system  300  may include one or more sails (e.g., mainsail  370  and/or headsail/spinnaker  371 ) coupled to mast  108   b  and configured to provide motive force to mobile structure  101 , solar panels  250   a  implemented as part of a sail bag for mainsail  370  as shown, and solar panels  250   b  coupled to transom  107   b  of mobile structure  101 . Each group of solar panels  250   a  and/or  250   b  may be used to provide solar charging power to help charge main battery  220 . Moreover, the expected or predicted power delivery of each group of solar panels  250   a  and/or  250   b  may be dependent on time of day, the absolute orientation of mobile structure  101  (e.g., relative to the sun), the relative orientation of mainsail  370  and/or headsail  371 , the sea state (e.g., level of chop or rolling waves obscuring solar panels  250   b ), and/or other factors, as described herein. The relationship of power delivery to any one or group of such factors may be characterized at manufacture, for example, or may be learned or supplemented with state measurements (e.g., power delivery measurements correlated with measured operational states of mobile structure  101 , including environmental states) made while underway, which may be accumulated over time to refine such relationship. 
     Electric propulsion provides limited range that can be highly dependent on a selected vessel speed.  FIG. 4  illustrates a graph  400  of runtime  410  and corresponding achievable linear range  420  as a function of vessel speed (e.g., assuming no water current effect and no assistance from wind) for electric propulsion system  200  and mobile structure  101  of  FIG. 2 . As can be seen from  FIG. 4 , as the desired or selected speed is decreased, the corresponding range generally increases, due to various factors including hull shape, hull drag, vessel weight, and electromechanical conversion efficiency, as described herein. 
     Motor-sailing (e.g., including e-sailing) can be extremely efficient and effective at certain wind angles, where small amounts of added mechanical power (e.g., electric or gas powered) can combine with the wind to extend the operational range of mobile structure  101 .  FIG. 5  illustrates a polar comparator chart or graph  500  showing the estimated speed of mobile structure  101  when provided motive force by electric power, wind, or a combination of wind and electrical power. In the embodiment shown in  FIG. 5 , chart  500  is generated with the assumption that there is a 4 knot true wind when estimating the speed of mobile structure  101  due to motive force provided by wind (e.g., and mainsail  370  and/or headsail  371 ) or a combination of wind and electric power. Plot  510  shows the estimated speed of mobile structure  101  generated by such true wind alone, as a function of relative wind angle/direction. Plot  520  (e.g., a dashed circle) shows the estimated speed of mobile structure  101  generated by electric drive motor  230  alone and consuming 750 W of power (e.g., with no wind effect). Plot  530  shows the estimated speed of mobile structure  101  generated by a combination of such true wind and electric drive motor  230  consuming 750 W of power. 
     As can be seen from chart  500 , motor-sailing or e-sailing (e.g., represented by plot  530 ) can generate a speed sometimes more than 25% greater than that achievable by electric power or wind alone, and generally greater for more than 80% of the possible relative wind directions, using the same power input. As such, controller  130  may be configured to use such relationship to help determine a range of mobile structure  101  that benefits from such combinatorial effect, for example, or to determine a track for mobile structure  101  that takes advantage of such relationship to increase the range of mobile structure  101 , reduce a rate of discharge of main battery  220 , reduce a total discharge of main battery  220  associated with reaching a particular waypoint or destination, increase a speed of mobile structure  101  with respect to navigation to a desired destination, and/or otherwise adjust navigation of mobile structure  101 , as described herein. 
       FIG. 6  shows a display view  600  including an operational range map or overlay for mobile structure  101  in accordance with an embodiment of the disclosure. In the embodiment presented by  FIG. 1 , display view  600  includes navigational chart  610  including operational range map  612  rendered as a shaded or colored semi-transparent area within dashed edge line  613  on chart  610 . In various embodiments, operational range map  612  may be configured to show an operational range of mobile structure  101  as determined based on an operational state of mobile structure  101  and/or one or more environmental conditions associated with a position and/or orientation of mobile structure  101 , a planned track or route  620  for mobile structure  101 , and/or a planned destination  624  for mobile structure  101 . Such environmental conditions may be measured by elements of system  100 , for example, or may be received from other vessels or weather services broadcasting such environmental conditions. 
     In various embodiments, controller  130  of system  100  may be configured to determine an operational state of mobile structure  101  based, at least in part, on a desired propulsion mode selected at propulsion mode selector  650  and/or monitoring and/or sensor data provided by elements of system  100  and/or  200 ; to determine environmental conditions associated with mobile structure  101 , the determined operational state of mobile structure  101 , and/or a planned track or route  620  or destination  624  for mobile structure  101 ; and to determine operational range map  612  based on such determined operational state and/or environmental conditions. Once operational range map  612  is determined (e.g., its shape and/or extent, relative to a position of mobile structure  101  and/or an orientation of chart  610 ), controller  130  may be configured to render operational range map  612  over chart  610  on a display of user interface  120 , for example, for display to a user to help facilitate route and/or passage planning for mobile structure  101 . In some embodiments, controller  130  may be configured to detect that the present operational state of mobile structure  101  along planned route  620  will result in unsafe navigation or be impossible to complete, for example, and to autopilot mobile structure along an alternative route  622  to an alternative destination  626 . As such, display view  600  provides a solution to autonomous or assisted route or passage planning, as described herein. 
     In the embodiment shown in  FIG. 6 , the pilot or user has used propulsion mode selector  650  to select (e.g., by user input provided to user interface  120 ) a power for electric drive motor  230  at 70% of full power with a slider of propulsion mode selector  650 , no use of generator  242 , use of mainsail  370  and/or headsail  371  (e.g., for e-sailing and/or combination of motor and wind propulsion), and reduced use of accessory power  222  (e.g., to turn off a cooler or refrigerator associated with accessory power sink  224 ). Such operational state of mobile structure  101  is reflected in the size and shape of operational range map  612 , as rendered over chart  610 . In general, operational range map  612  may be configured to show straight-line range capability to a minimum desired charge state, which may be set by a pilot or user (in  FIG. 6 , the minimum charge state for main battery  220  is set to zero). If the pilot reduces the power for electric drive motor  230 , then operational range map  612  will generally expand, and more distant destinations will be shown within reach (e.g., overlaid by operational range map  612 ), and the shape of operational range map  612  will change according to the applicable/selected sail/motor power mix, similar as shown in  FIG. 5 , and according to the applicable environmental conditions. 
     In some embodiments, controller  130  may be configured to render route  620  on chart  610  as the track to the chosen destination  624  and to render state of charge (SOC) identifiers  630 ,  632 ,  634  at each waypoint and, in addition, at intermediate points for relatively long tracks in between waypoints (e.g., shown as circular nodes along route  620  and/or alternative route  622 ). An estimated time of arrival (ETA) and SOC identifier  644  may be rendered at planned destination  624 . As shown in  FIG. 6 , display view  600  indicates that passage planning system  100  estimates reaching planned destination  624  (Lymington harbor) with 5% charge remaining in main battery  220 . 
     In various embodiments, a pilot may interrogate other waypoints or alternative route  622  and/or alternative destination  626  by selecting alternative destination  626 . Upon detecting such user selection, controller  130  may be configured to render a dotted black track line to show a recommended alternative route  622  to alternative destination  626  with corresponding estimated SOCs and, with respect to alternative destination  626 , an ETA and SOC identifier  642 . Alternative destination  626  (Yarmouth harbor) is shown as reachable with 9% charge remaining in main battery  220 . In some embodiments, each SOC identifier may be replaced with an ETA and SOC identifier, according to one or more user display settings and/or the number of waypoints shown in display view  600  (e.g., fewer waypoints and identifiers might allow larger and more informative identifier to be rendered without cluttering display view  600  or obscuring important chart detail). In various embodiments, operational range map  612  is indicative (e.g., straight line paths are not generally possible), but the cursor/dotted-track may be normative (e.g., system  100  may be configured to determine a best (e.g., lowest power usage, safest traversal, quickest traversal) route to a selected waypoint or destination. 
     When determining operational range map  612 , planned route  620 , and/or alternative route  622 , system  100  may account for wind direction and speed, water current, sea state, and/or other factors, for example, and project these factors forward in time, based on one or more environmental forecasts (e.g., meteorological or GRIB forecasts, tidal databases) and/or (e.g., in case of air or sea states) a mix of forecast and measured or known environmental conditions, such as wind direction and speed (e.g., wind over tide produces stronger seas). The effect of sea state on performance of mobile structure  101  may be provided in tabular form or estimated based on a simplified analytical function, as described herein. 
     In some embodiments, system  100  may be configured to determine and/or select a particular power for electric drive motor  230  upon receiving a user selected destination and/or desired minimal SOC, for example, to ensure reaching planned destination  624 , for example, or to account for changing and/or unpredicted environmental conditions along route  620 . Thereby, system  100  is able to optimize power utilization to account for the present and future conditions (e.g., operational state of mobile structure  101  and/or various environmental conditions). For example, if the tide will turn in one hour, it may be futile to push into it; it may be better to conserve energy for the next 45 minutes then apply a higher power level, in order to reach planned destination  624  at a desired ETA. 
     In further embodiments, system  100  may be configured to determine a route start time based on one or more user selected passage criteria. For example, a user may select to emphasize one or more of shortest journey time, least fuel consumed, smoothest ride (e.g., avoiding wind-over-tide scenarios), a specific arrival time, a range of arrival times, a combination of these, and/or other passage criteria, for example, generally intended for selection before departure, where the journey start-time is determined based on such criteria. 
     While such route or passage planning techniques are intended for use with electric or hybrid electric (diesel/sail/electric in any combination) watercraft, they may be applicable to any power source, including combustion engine based propulsion systems, and to terrestrial or air based mobile structures. Moreover, such techniques are not limited to planning; similar systems and techniques may be used to dynamically adjust power to electric drive motor  230 , for example, to maintain an optimal balance between sail and motor power as wind speed and/or direction changes (e.g., as described with respect to polar chart  500  of  FIG. 5 ). For example, a pilot or user may select passage criteria including holding a steady 5 kts along planned route  620 , and system  100  may increase power to electric drive motor  230  as wind speed drops and reduce power as wind speed increases. 
     In some embodiments, system  100  may be configured to determine a risk profile associated with a number of selected or otherwise determined alternative routes (e.g., planned route  620  and alternative route  622 ) and render each alternative route according to a preselected color mapping to indicate one route is riskier than another. In other embodiments, system  100  may be configured to render operational range map  612  according to a similar color mapping to indicate navigation to portions of operational range map  612  is riskier than navigation to other portions. In various embodiments, such color mapping may be configured to emphasize differentiation across a particular range of risk values within the risk profile, which may generally be implemented as a set of percentages (e.g., each 0-100%) linked with a particular route, set of waypoints, and/or other sets of spatial and/or temporal positions represented on chart  610 . 
     Such risk profile may be based on a set of risk criteria, which may be selected by a user as part of the configuration settings or parameters for passage planning system  100 . For example, such risk criteria may include risk of failing to reach a particular position within operational range map  612  due to known variability (or lack of reliability) of environmental forecasts associated with a route to such position, risk of being stranded without electrical power at such position (e.g., at sea vs. at berth, determined with or without applicable e-sailing capabilities), risk of delay in reaching such position (e.g., when the passage criteria includes a desired arrival time) caused by environmental conditions (e.g., tide, wind direction and strength, measured and/or forecasted), an operational state of mobile structure  101  (e.g., planned accessory power draw, availability of solar charging), and/or route timing criteria (e.g., tidal gate or lock opening/closing) along the route to such position. 
     In various embodiments, system  100  may be configured to update the risk profile and the rendering of alternative routes and/or operational range map  612  as mobile structure traverses operational range map  612 . In some embodiments, system  100  may be configured to render operational range map  612  according to extents based on an achievable linear range of electric propulsion system  200 , various environmental conditions, an operational state of mobile structure  101 , and a user selected maximum acceptable risk value (e.g., a type of risk criteria). 
       FIGS. 7-10  illustrate flow diagrams of control loops to provide passage planning in accordance with embodiments of the disclosure. In particular,  FIGS. 7-10  include control loops to determine a predicted speed of mobile structure  101  based, at least in part, on applicable forecasted environmental conditions, the sailing characteristics of mobile structure  101 , and/or the assisted sailing (e.g., e-sailing) capabilities of mobile structure  101 . In some embodiments, the operations of  FIGS. 7-10  may be performed by controller  130  processing and/or operating on signals received from one or more of sensors  140 - 148 , navigation control system  190 , user interface  120 , and/or other modules  180 . For example, in various embodiments, control loop  700  (and/or other control loops of  FIGS. 8-10 ) may be implemented and/or operated according to any one or combination of the systems and methods described in International Patent Application No. PCT/US2014/13441 filed Jan. 28, 2014 and entitled “STABILIZED DIRECTIONAL CONTROL SYSTEMS AND METHODS,” and/or U.S. patent application Ser. No. 14/321,646 filed Jul. 1, 2014 and entitled “STABILIZED DIRECTIONAL CONTROL SYSTEMS AND METHODS,” each of which are hereby incorporated by reference in their entirety. 
     In accordance with an embodiment, each block may be implemented entirely as instructions executed by controller  130 , for example, or may be implemented in a combination of executable instructions and hardware, such as one or more inductors, capacitors, resistors, digital signal processors, and other analog and/or digital electronic devices. It should be appreciated that any step, sub-step, sub-process, or block of in the control loops may be performed in an order or arrangement different from the embodiment illustrated by  FIGS. 7-10 . For example, although control loop  720  shown in detail in  FIG. 8  includes block  828 , in other embodiments, block  828  may not be present, for example, and/or may be replaced with a look up table generated through use of one or more sensors providing corresponding measured data. 
     As shown in  FIG. 7 , control loop  700  includes speed predictor block  720  providing a predicted linear/longitudinal speed (e.g., speed through water) for mobile structure  101 . For example, speed predictor block  720  may be configured to receive a time series of forecasted environmental conditions (e.g., true wind velocities (speed and direction)  710 , current velocities (speed and direction)  712 ) and predicted and/or selected operational states of mobile structure  101  (e.g., headings  714  of mobile structure  101 , mechanical propulsion powers  716 ), which may be associated with a planned route for mobile structure  101 , for example, and determine a time series of predicted speeds  770  of mobile structure  101 . As described herein, control loop  700  may be used provide predicted speeds  770  as part of a passage planning process before mobile structure  101  initiates a planned route, for example, and may also be used during transit along a planned route to, for example, update operational range map  612 , update a risk profile associated with operational range map  612  and/or planned route  620  and alternative route  622 , or to determine or update any other passage state data associated with a passage plan or route, as described herein. 
     As shown in  FIG. 8 , speed predictor block  720  may be implemented by apparent wind simulator block  820 , sailing polar converter block  822 , thrust and drag curve blocks  824  and  825 , applied thrust predictor block  828 , and various other blocks configured to generate predicted speeds  870  of mobile structure  101 . For example, apparent wind simulator block  820  may be configured to receive forecasted environmental condition and predicted and/or selected operational state inputs  810  as shown and provide simulated apparent wind velocities (speed and direction, as felt by/in the coordinate frame of mobile structure  101 ) to sailing polar converter block  822 . Sailing polar converter block  822  may be configured to receive the simulated apparent wind velocities and provide predicted sailing speeds to thrust curve block  824 . Thrust curve block  824  may be configured to convert the predicted sailing speeds to predicted sailing thrusts (e.g., in units of force) generated by mobile structure  101  in response to the predicted sailing speeds and provide the predicted sailing thrusts to combinatorial block  830 . 
     Applied thrust predictor block  828  may be configured to convert selected and/or predicted mechanical propulsion powers  812  and prior predicted speeds for mobile structure  101  (e.g., as converted by unit conversion block  826  as necessary) into predicted mechanical propulsion thrusts generated by mobile structure  101  in response to mechanical propulsion powers  812  and provide the predicted mechanical propulsion thrusts to combinatorial block  830 . Drag curve block  825  may be configured to convert prior predicted speeds for mobile structure  101  into predicted drag thrusts generated by mobile structure  101  in response to the prior predicted speeds and provide the predicted drag thrusts to combinatorial block  830 . 
     Combinatorial block  830  may be configured to combine the predicted sailing thrusts, mechanical propulsion thrusts, and drag thrusts and generate predicted passage thrusts, which may then be converted into predicted speeds  870  of mobile structure  101  by force to acceleration converter block  832 , acceleration to velocity integrator block  834 , and/or unit conversion block  836 , as desired. In some embodiments, force to acceleration converter block  832  may be configured to receive a time series of predicted masses for mobile structure  101 , where the mass of mobile structure  101  changes over the course of a planned route, such as due to fuel consumption, for example. 
     In various embodiments, parameters for sailing polar converter block  822 , thrust and drag curve blocks  824  and  825 , and/or applied thrust predictor block  828  may be supplied by a manufacturer, for example, or may be determined through directed sea trials (patterns of navigational maneuvers of mobile structure  101 ) or through accumulation of sensor data over time that measures the response of mobile structure  101  to various environmental conditions and/or operational states of mobile structure  101 . In some embodiments, thrust and drag curve blocks  824  and  825  may use identical parameters, where, as shown in  FIG. 8 , drag curve block  825  is driven by the predicted speed of mobile structure  101  and thrust curve block  824  is driven by predicted sailing speed generated by mobile structure  101  in response to an applicable apparent wind. 
     As shown in  FIG. 9 , apparent wind simulator block  820  may be implemented by various coordinate conversion blocks  920 ,  932 ,  942 ,  944 , and  952 ; and various combinatorial blocks  930 ,  940 , and  950 , configured to add the various vectors of wind, current, and velocity of mobile structure  101  (heading and speed) to generate simulated apparent wind velocities. For example, coordinate conversion blocks  920  may be configured to convert environmental condition inputs  910  into cartesian coordinates and provide them to combinatorial block  930 , which combines them and provides the combined environmental speed effects to coordinate conversion block  932 . Coordinate conversion block  932  converts the environmental speed effects back to polar coordinates and combinatorial block  940  transforms them to the frame of mobile structure  101 . Coordinate conversion block  942  converts the transformed environmental speed effects to cartesian coordinates and provides them to combinatorial block  950 . Coordinate conversion block  944  converts prior predicted speeds of mobile structure  101  (e.g., in the frame of mobile structure  101 ) to cartesian coordinates and provides them to combinatorial block  950 , which combines the prior predicted speeds and the transformed environmental speed effects to produce apparent wind velocities in cartesian coordinates. Coordinate conversion block  952  converts those cartesian apparent wind velocities into polar apparent wind velocities  960 . 
     As shown in  FIG. 10 , sailing polar converter block  822  may be implemented as executable script and/or program code configured to receive apparent wind velocities and generate corresponding predicted sailing speeds, based, at least in part, on a true or apparent wind polar (e.g., similar to plot  510  in  FIG. 5 ), which may then be provided to thrust curve block  824 . For example, sailing polar converter block  822  may be configured to determine a predicted sailing speed generated by mobile structure  101  in response to a simulated apparent wind provided by apparent wind simulator block  820  using a true wind polar (e.g., discretized into true wind polar matrix  1002 ) associated with mobile structure  101 . In the embodiment shown in  FIG. 10 , true wind polar matrix  1002  is converted to an apparent wind polar matrix in block  1004  that is used (e.g., through interpolation) to determine an appropriate predicted sailing speed associated with the specific applied apparent wind velocity. 
       FIG. 11  illustrates a flow diagram of a process  1100  to provide range estimation and/or facilitate passage planning for mobile structure  101  implemented with passage planning system  100  in accordance with an embodiment of the disclosure. More generally, process  1100  may be used to provide general navigational control for mobile structure  101 . It should be appreciated that any step, sub-step, sub-process, or block of process  1100  may be performed in an order or arrangement different from the embodiments illustrated by  FIG. 11 . For example, in other embodiments, one or more blocks may be omitted from or added to the process. Furthermore, block inputs, block outputs, various sensor signals, sensor information, calibration parameters, and/or other operational parameters may be stored to one or more memories prior to moving to a following portion of a corresponding process. Although process  1100  is described with reference to systems, processes, control loops, and images described in reference to  FIGS. 1A-10 , process  1100  may be performed by other systems different from those systems, processes, control loops, and images and including a different selection of electronic devices, sensors, assemblies, mobile structures, and/or mobile structure attributes, for example. 
     In block  1102 , an operational state of and environmental conditions associated with a mobile structure are determined. For example, controller  130  may be configured to determine an operational state of mobile structure  101  based on monitoring and/or sensor data provided by elements of system  100  and/or  200 . In some embodiments, such operational state may include an electric propulsion state of system  200 , a position and/or orientation of mobile structure  101 , and/or other operational states of mobile structure  101 , as described herein. Such operational state may be determined based on monitoring data provided by elements of systems  100  and/or  200 , such as a charge state for main battery  230 , for example, and/or sensor data provided by elements of system  100 , such as orientation and/or position data provided by one or more of orientation sensor  140 , gyroscope/accelerometer  144 , GNSS  146 , and/or a combination of those, and/or other sensor data or control signals provided by other elements of system  100 . In related embodiments, controller  130  may be configured to determine an operational state of mobile structure  101  based on a desired propulsion mode selected at propulsion mode selector  650 , as described herein. 
     In some embodiments, controller  130  may be configured to determine environmental conditions associated with mobile structure  101  based on sensor data provided by elements of system  100 . For example, controller  130  may be configured to receive a wind speed and/or direction from speed sensor  142 , a water current speed from GNSS  146  and/or speed sensor  142 , motion information from gyroscope/accelerometer  144  indicating sea state, a time of day and/or sun position from GNSS  146 , and/or other environmental conditions from other vessels or weather services through a communications module (other modules  180  and/or communications module  270 ), and such conditions may be associated with a present and/or planned position, orientation, and/or route of mobile structure  101 . 
     In some embodiments, the operational state includes an electric propulsion state, a heading, and/or a position of mobile structure  101  and the environmental conditions include a wind velocity and/or a current velocity associated with the mobile structure and/or a planned route for the mobile structure. For example, controller  130  may be configured to determine the environmental conditions by receiving environmental sensor data, position data, and/or orientation data from corresponding sensors mounted to mobile structure  101  and/or determining a wind velocity and/or a current velocity associated with mobile structure  101  based on the environmental sensor data, the position data, and/or the orientation data. 
     In other embodiments, controller  130  may be configured to determine passage criteria associated with a planned route for mobile structure  101 , such as planned route  620  and/or destination  624 . For example, controller  130  may be configured to receive a first portion of the passage criteria as user input provided to user interface  120  and to determine a second portion of the passage criteria based, at least in part, on the first portion of the passage criteria and the operational state of mobile structure  101 . In some embodiments, the first portion of the passage criteria includes a destination and a desired arrival time and the second portion of the passage criteria comprises a series of waypoints defining the planned route and a corresponding series of mechanical propulsion power levels to be provided by main battery  220  of mobile structure  101  to propulsion system  200 . More generally, passage criteria may be determined by user selection of passage criteria and/or other parameters, as disclosed herein. 
     In block  1104 , an operational range map is determined. For example, controller  130  may be configured to determine a size, shape, and/or extent of operational range map  612  based on the operational state and/or environmental conditions determined in block  1102 . In some embodiments, controller  130  may be configured to determine a set of straight line range estimations from a current position of mobile structure  101 , differentiated from each other by absolute orientation (e.g., heading), where each straight line range estimation is based on a desired speed and/or power output, an estimated wind direction and speed, an estimated water current direction and speed, an electric propulsion state of electric propulsion system  200 , and/or other factors, as described herein. Controller  130  may then determine the size, shape, and/or extent of operational range map  612  by linking the ends of adjacent lines in the set of straight lines to form edge line  613  and designating the area within edge line  613  and including the position of mobile structure  101 , as shown on chart  610 , as operational range map  612 . 
     In related embodiments, controller  130  may be configured to use position sensor/GNSS  146  to set an initiation position for the generation of operational range map  612 . In such embodiments, the determining the operational range map may include determining a set of straight line range estimations from the initiation position of mobile structure  101  provided by GNSS  146 , where each straight line range estimation is based, at least in part, on a series of predicted speeds of the mobile structure along each straight line range estimation, and where each predicted speed is based, at least in part, on the operational state of the mobile structure and a true or apparent wind polar associated with the mobile structure, as shown and described in  FIGS. 7-10 . 
     In block  1106 , an operational range map is rendered on a navigational chart. For example, controller  130  may be configured to render operational range map  612  over chart  610  on a display of user interface  120 . In some embodiments, controller  130  may be configured to render SOC identifiers along planned route  620 , for example, and/or ETA and SOC identifiers at planned destination  624 . In related embodiments, controller  130  may be configured to receive user selection of additional waypoints, alternative route  622 , alternative destination  626 , and/or other selections corresponding to points on chart  610 , for example, and to render SOC and/or ETA and SOC identifiers with such selections. Controller  130  may also be configured to render propulsion mode selector  650  over a portion of chart  610  and to receive user selection of a particular propulsion mode associated with operation of mobile structure  101 . Controller  130  may be configured to update the determined operational state of mobile structure  101  according to the selected propulsion mode, for example, and determine operational range map  612  based on such updated operational state. 
     In block  1108 , an operational state of a mobile structure is adjusted. For example, controller  130  may be configured to detect that planned destination  624  is outside operational range map  612 . Upon such detection, controller  130  may be configured to display or sound an alert to the pilot of mobile structure  101 , for example, and/or to adjust an operational state of mobile structure  101  to expand operational range map  612  to include planned destination  624  or to pilot mobile structure  101  according to alternative route  622  to alternative destination  626  that is within operational range map  612 . In some embodiments, controller  130  may be an operational state controller for mobile structure  101  and may be configured to adjust the operational state of mobile structure  101  based, at least in part, on the operational range map determined in block  1104  and/or passage criteria associated with a planned route for the mobile structure and determined in block  1102 . In such embodiments, the operational state of mobile structure  101  may include a main battery charge level for main battery  220  of propulsion system  200 , and the adjusting the operational state of mobile structure  101  may include adjusting mechanical propulsion power  221  provided by main battery  220  to electric drive motor  230  of propulsion system  200 . 
     In various embodiments, a planned route and/or destination may initially be undefined, and user selection of such route and/or destination may occur after operational range map  612  is rendered on a display of user interface  120 . Once such planned route or destination is selected, system  100  may be configured to determine an operational state of mobile structure  101  to reach such planned destination at a selected ETA, for example, and/or according to other passage criteria. If a planned route or destination is initially outside operational range map  612 , system  100  may be configured to determine an updated operational state of mobile structure  101  to expand operational range map  612  and/or adjust the planned route to reach such planned destination, which may also account for one or more associated passage criteria. If, during navigation along a planned route towards a planned destination, environmental conditions change such that the planned destination is outside an updated operational range map  612  or is otherwise unsafe, system  100  may be configured to alert the pilot of mobile structure  101  and navigate to a safe anchor position, a charging station, a harbor within the updated operational range map  612 , and/or according to various selected and/or updated passage criteria. 
     Embodiments of the present disclosure can thus provide reliable and accurate route and/or passage planning for mobile structures. Such embodiments may be used to provide assisted and/or fully autonomous navigation of a mobile structure and may assist in the operation of other systems, devices, and/or sensors coupled to or associated with the mobile structure, as described herein. 
     In accordance with additional related embodiments of the present disclosure, passage planning systems and methods may provide techniques for traversing a planned route safely using augmented reality (AR) display views, as described herein. Passage planning systems with AR display views help users visualize and identify critical objects and hazards along their planned route, particularly in the context of regulatory rules and personal preferences governing the traversal of such route. For example, cardinal marks have a safe side, boats should pass port to port, channel marks should be respected, fishing floats avoided, and the particular route excursion chosen to avoid such objects can be tailored to a particular user preference. Disclosed herein are techniques to apply maritime navigation rules and present a suggested action to a user in a clear simple manner, which may be accompanied by audible alarms. Also disclosed are techniques to use such rule-based approach to enable a self-driving vessel. 
       FIGS. 12A-B  illustrate diagrams of an imaging system  1210  for use with a passage planning system in accordance with an embodiment of the disclosure. For example, imagery provided by imaging system  1210  may be used to generate AR display views, as described herein. As shown in diagram  1200  of  FIG. 12A , imaging system  1210  may be mounted to the top of a mast of mobile structure  101  to provide a relatively wide field of view (FOV)  1212  that can include the horizon and the water surface within 1-2 boat lengths of mobile structure  101 , as shown. 
     Contemporary digital cameras have so many pixels that they can combine a relatively wide FOV  1212  with good resolution (i.e., viewing range), which allows electronic stabilization to be a useful an effective stabilization technique. However, infrared cameras, and particularly thermal cameras, typically have a smaller number of available pixels, and so it is preferable to stabilize the roll axis of the FOV and use electronic stabilization only on the pitch axis. This makes such camera useful for sailboats as well as power boats, and by making the camera small and light, it can be installed at the masthead, as shown in diagram  1200 , providing a clear viewpoint even when under sail. 
       FIG. 12B  illustrates imaging system  1210  with such mechanical roll stabilization. For example, as shown in  FIG. 12B , imaging system  1210  includes mounting arm  1222  and sealed housing  1224  configured to mount to the mast of mobile structure  101 . Inside housing  1224  are mechanical stabilizer  1230  and imaging module  1232 . In various embodiments, mechanical stabilizer  1230  may be configured to provide mechanical roll stabilization only, and imaging system  1210  and/or controller  130  may be configured to provide electronic pitch and/or yaw stabilization (with respect to the FOV of imaging system  1210 ). In some embodiments, mechanical stabilizer  1230  may be configured to provide mechanical roll and pitch stabilization. Mechanical stabilizer  1230  may be implemented by an articulated mount for imaging module  1232  and a motor, actuator, and/or weight, for example. Imaging module  1232  may be implemented as a visible spectrum or infrared spectrum (thermal) camera, for example, or as a combined or multi-spectrum camera. Imaging system  1210  may be powered by solar cells or by wire to other elements of system  100 , for example, and may communicate imagery to controller  130  and/or user interface  120  via wired and/or wireless data connections. 
     While it is unusual to stabilize only the roll axis mechanically, and to stabilize the pitch but not yaw axes electronically, such combination is highly suited to maritime applications for thermal cameras and is relatively cost efficient to manufacture (see  FIG. 12B , where a motor (mechanical stabilizer  1230 ) provides roll rotational alignment, and the window does not move, and is small and so low-cost). The approach is also valid for visible cameras, and in some applications, it may be desirable to stabilize pitch mechanically too. 
       FIG. 13  shows an augmented reality (AR) display view  1300  for mobile structure  101  with passage planning system  100  in accordance with an embodiment of the disclosure. As shown in  FIG. 13 , AR display view  1300  has an FOV (e.g., provided by imaging system  1210 ) that includes sky  1302 , horizon  1304 , and sea surface  1306  from the horizon and approaching a perimeter of mobile structure  101 . Also shown in AR display view  1300  are heading indicator  1310 , detector range indicator  1312 , and various AR markers rendered within AR display view  1300  to indicate various characteristics of recognized objects. 
     For example, vessel marker  1320  includes a nationality and descriptor of the vessel, range to the vessel, and includes a header rendered green to show no risk of collision. Vessel marker  1322  has much the same information but its header is rendered red to show there may be risk of collision based on the heading of that vessel. Vessel  1324  has not been rendered with a marker because it hasn&#39;t been recognized or it is sufficiently outside the planned route of mobile structure  101 . Marker  1330  includes similar information for a stationary drill rig but lacks a colored header because it is too far away to evaluate for collision purposes. Marker  1340  indicates a user-defined saved waypoint corresponding to a desired fishing area. Other markers may indicate range to or depth of water at that point. Embodiments described herein supplement AR display view  1300  with additional navigational information, such as navigational error alerts, safe areas associated with warning buoys, and/or other navigational questions. Embodiments also use similar techniques to autopilot mobile structure  101  and make safety critical course changes automatically. 
     For example,  FIGS. 14A-C  show AR display views  1400 ,  1402 ,  1404  for mobile structure  101  with passage planning system  100  in accordance with an embodiment of the disclosure. In  FIG. 14A , AR display view  1400  includes planned route indicator  1420  and navigation alert  1422  providing navigation information related to buoy  1410  and vessels  1412 . In  FIG. 14B , AR display view  1402  includes planned route indicator  1424  that has been adjusted to avoid buoy  1414 . In  FIG. 14C , AR display view  14 C includes navigation alert/shallows indicator  1426  to indicate which side of channel buoy  1416  is not safely navigable. 
     In general, system  100  may be configured to generate the various AR display views and safety mechanisms by (1) aggregating sensor data from various sensors of system  100  into a single coherent passage database that is used to describe the area surrounding mobile structure  101 ; (2) adding navigation requests (e.g., provided to navigation control system  190 ) to the passage database; (3) using an expert system (e.g., using machine learning techniques) to determine a set of potential navigation hazard contacts (e.g., collisions, groundings) based on the passage database; (4) prioritizing the set of potential navigation hazard contacts; (5) generating a set of display overlays and audible alarms for all potential navigation hazard contacts with hazard priorities above a threshold priority; (6) autopiloting mobile structure  101  to avoid the potential navigation hazard contacts with hazard priorities above the threshold priority. 
     For example, the sensor data may be processed by the expert system (e.g., implemented by a convolutional neural network (CNN)) to detect and classify potential navigation hazards, for example, including vessels, buoys, diver down flags, anchor inverted triangle, and/or other potential navigation hazards. The passage database may include target headings, speeds, and/or routes, true or apparent wind velocities, coarse over ground, waypoint advance requests, for example, and may also include crowd sourced navigation data provided by other vessels. The expert system (e.g., implemented within or by controller  130 , for example) may be configured to determine potential navigation hazard contacts based on all detected vessel&#39;s velocities, as well as requested changes to the velocity of mobile structure  101 . In some embodiments, such expert system may be configured to project other vessel&#39;s motion under the assumption that their motion is constant to first (constant velocity) or second (constant acceleration) order. In related embodiments, applicable regulatory rules (e.g., “international regulations for preventing collisions at sea  1972  (COLREGs)”) may be applied to help project other vessel&#39;s motion. For example, two powered vessels heading directly towards each other should both turn to starboard and pass port to port and so have predictable evolving routes. 
     In various embodiments, controller  130  (e.g., the expert system) may be configured to prioritize each determined potential navigation hazard contact according to immediacy and severity. Immediacy is defined as inversely proportional to the time to reach the potential navigation hazard contact (e.g., impact in the case of collision, shallow threshold crossing, or crossing a line of channel marks, etc.). Severity is defined as proportional to risk of property damage or human injury; impact with another vessel has higher severity than entering shallow water (where grounding is not imminent). According to such strategy, rapidly approaching vessels or vessels behaving unusually may be flagged as potential navigation hazard contacts from further away, creating a higher level of severity. 
     The expert system may be configured to determine when to show warnings and which views to show, without the user having to intervene. Similarly, the expert system may be configured to choose display views and apps according to context (e.g., showing docking views and entering assisted docking mode when close to a dock). The highest priority potential navigation hazard contacts trigger a set of display overlays and audible alarms, and system  100  displays the highest priority potential navigation hazard contacts to the user. Alarm characteristics are chosen to reflect the severity and urgency, with increasing volume and cadence as the immediacy and severity increase. If system  100  is autopiloting mobile structure  101 , after alarming for a maximum inaction period (e.g., 20s), system  100  may be configured to adjust a heading and/or speed of mobile structure  101  to avoid the potential navigation hazard contact. For example, a target heading may be adjusted, then once past a potential navigation hazard contact, restored, to route mobile structure  101  around a fishing float. The direction of turn may be selected or determined to minimize risk (collision with other vessels, shallow water, etc.). 
     CNNs often operate most efficiently with fixed frame sizes (e.g., 512×512), yet maritime imagery often needs lots of pixels for reliable monitoring. This means that a CNN might need to process  100   s  of fixed frames to process a full 360 degree maritime scene, and even then, the CNN would likely be confused by large objects (e.g., a single vessel close-up, could be larger than 512×512). Detailed (distant) objects tend to be close to the horizon, so for many maritime applications it is only necessary to process a strip just at or below the horizon to reliably detect and classify the fine pixelated far off objects. Big objects close-up can be processed by the CNN by down sampling. 
       FIG. 15  shows a region-differentiated image processing strategy  1500  for AR display views for mobile structure  101  with passage planning system  100  in accordance with an embodiment of the disclosure. For example, as shown in  FIG. 15 , region-differentiated image processing strategy  1500  includes a first large region  1510  that encompasses the entirety of the FOV of imaging system  1210 , for example, and a number of (e.g., seven) additional smaller overlapping regions  1520  distributed across the horizon in the FOV of imaging system  1210 , as shown, each being the same pixel size as the applicable CNN. In some embodiments, system  100  may be configured to downsample full frame region  1510  to a specified fixed frame size (e.g., using decimation, bicubic downsampling, etc.) associated with a CNN implemented by controller  130 , for example, and the result of such processing can be detection and classification of relatively large port channel buoy  1530 . System  100  may then identify and process horizon regions  1520  (e.g., using horizon/contrast detection and a desired overlap distribution), and the result of such processing can be the detection and classification of relatively small objects, such as buoy  1532  and powerboat  1534 . Embodiments using image processing strategy  1500  or similar are able to significantly reduce the computing resources necessary to provide reliable object detection and classification, as described herein. 
     Embodiments of system  100  integrated with imaging system  1210  may be used to create a visual navigation log, for example, which could be used for insurance purposes and/or monitored by a rental company to contemporaneously analyze detected near-misses or other dangerous behavior over the rental period. Similar image processing techniques can be used to implement search and rescue systems, where feeds into the database include man over board location, vessel-in-trouble location, search area, search pattern, etc. Such imagery feed can include a live link to coastguard or border protection services or craft. Embodiments can be used to implement fishing applications, where desirable fishing spots or waypoints are included in the passage database, along with thermocline, water temperature, and/or other sensor data. Embodiments can also be used to implement sailboat racing applications, such that the passage database can include race marks, wind information (which can be visualized in 2d or 3d), live positions of competing ships, water currents, etc. Specialized racing rules can be included in the database (similar to the regulatory rules) so that system  100  indicates through an AR display view whether a pilot should give or is due water at a race mark, or if a pilot has broken a rule and must perform penalty turns. 
       FIG. 16  illustrates a flow diagram of a process  1600  to provide AR display views for mobile structure  101  in accordance with an embodiment of the disclosure. It should be appreciated that any step, sub-step, sub-process, or block of process  1600  may be performed in an order or arrangement different from the embodiments illustrated by  FIG. 16 . For example, in other embodiments, one or more blocks may be omitted from or added to the process. Furthermore, block inputs, block outputs, various sensor signals, sensor information, calibration parameters, and/or other operational parameters may be stored to one or more memories prior to moving to a following portion of a corresponding process. Although process  1600  is described with reference to systems, processes, control loops, and images described in reference to  FIGS. 1A-15 , process  1600  may be performed by other systems different from those systems, processes, control loops, and images and including a different selection of electronic devices, sensors, assemblies, mobile structures, and/or mobile structure attributes, for example. 
     In block  1602 , ranging sensor data from a mobile structure is aggregated into a passage database. For example, controller  130  may be configured to aggregate perimeter sensor data provided by perimeter ranging system  148  into a passage database, as described herein. In some embodiments, the passage database may include, in addition to the perimeter sensor data, a regulatory navigation ruleset (e.g., local, territorial, international), user navigation preferences (e.g., a navigation comfort mode, navigational aggressiveness, a minimum priority threshold, and/or other user navigation preferences), passage criteria associated with a planned route for the mobile structure (e.g., a planned destination, time of arrival, route, and/or a minimum SOC), and/or navigation control signals (e.g., a time series of navigation control signals) provided to navigation control system  190  of mobile structure  101  (e.g., by user interface  120  and/or controller  130 ). 
     In some embodiments, controller  130  may be configured to additionally or alternatively aggregate environmental sensor data provided by one or more environmental sensors mounted to or within mobile structure  101  into the passage database. In related embodiments, the passage database may include a fishing compendium comprising a variety of fishing-related data, such as positions of fishing locations, seasonal and species fishing catch rates, suggested baits or lures, correlations of catch rates to local time of day, weather (e.g., sun or cloud cover), sea surface temperatures, wind, tide, lunar or solar activity, and/or other environmental conditions. 
     In block  1604 , potential navigation hazard contacts are determined. For example, controller  130  may be configured to determine a set of potential navigation hazard contacts based, at least in part, on the passage database updated in block  1602 . In some embodiments, controller  130  may be configured to detect and classify one or more navigation hazards within a preselected range of mobile structure  101  (e.g., the sensing range of an associated ranging sensor system) based, at least in part, on the ranging sensor data in the passage database. Controller  130  may then identify at least one of the one or more navigation hazards as the set of potential navigation hazard contacts based, at least in part, on a projected course of mobile structure  101  (e.g., a target heading, target speed, and/or a target or planned route for mobile structure  101 ) and a position and/or a projected motion of the at least one navigation hazard. Such projected motion may assume a detected velocity or acceleration of the at least one navigation hazard be constant over the time period of the projection. 
     In some embodiments, the ranging sensor system includes imaging system  1210  implemented as an embodiment of perimeter ranging system  148 . In such embodiments, controller  130  may be configured to process imagery provided by imaging system  1210  according to region-differentiated image processing strategy  1500  using a fixed frame CNN characterized by a fixed frame pixel size that is smaller than a frame pixel size of the imagery provided by the imaging system, as described herein. 
     In additional or alternative embodiments, where the passage database comprises a fishing compendium, controller  130  may be configured to determine a set of potential fishing locations based, at least in part, on the passage database updated in block  1602 . Such set of potential fishing locations may be selected or identified within the passage database based on an achievable navigational range of mobile structure  101 , for example, or desired time of arrival at a destination (e.g., to return to a berth). 
     In block  1606 , hazard priorities for potential navigation hazard contacts are determined. For example, controller  130  may be configured to determine a set of hazard priorities corresponding to the set of potential navigation hazard contacts determined in block  1604  based, at least in part, on the passage database updated in block  1602 . In some embodiments, controller  130  may be configured to determine an immediacy for each potential navigation hazard contact based, at least in part, on an estimated time for the mobile structure to reach the corresponding navigation hazard; determine a severity for each potential navigation hazard contact based, at least in part, on a size, shape, velocity, and/or type of the corresponding navigation hazard; and determine the set of hazard priorities based on a combination (e.g., sum) of the immediacy and severity for each potential navigation hazard contact in the corresponding set of potential navigation hazard contacts. 
     In additional or alternative embodiments, where the passage database comprises a fishing compendium, controller  130  may be configured to determine a set of fishing location priorities corresponding to the set of potential fishing locations determined in block  1604  based, at least in part, on the passage database updated in block  1602 . 
     In block  1608 , user alerts for potential navigation hazard contacts are generated. For example, controller  130  may be configured to generate a user alert for each potential navigation hazard contact based, at least in part, on its corresponding priority and a preselected minimum priority threshold. In some embodiments, when generating a user alert, controller  130  may be configured to render a navigation alert identifying one or more potential navigation hazard contacts with corresponding hazard priorities above the preselected minimum priority threshold on a display of user interface  120  associated with mobile structure  120 . In other embodiments, controller  130  may be configured to generate an audible alert via a speaker of user interface  120  for at least one of the one or more potential navigation hazard contacts with corresponding hazard priorities above the preselected minimum priority threshold. 
     In additional or alternative embodiments, where the passage database comprises a fishing compendium, controller  130  may be configured to render navigation information or identifiers identifying one or more potential fishing locations with corresponding fishing location priorities above a preselected minimum fishing priority threshold on a display of user interface  120  associated with mobile structure  120 . Controller  130  may also be configured to generate an audible alert via a speaker of user interface  120  for at least one of the one or more potential fishing locations with corresponding fishing location priorities above the preselected minimum fishing priority threshold. 
     In block  1610 , an operational state of a mobile structure is adjusted. For example, controller  130  may be configured to adjust, using operational state controller coupled to or within mobile structure  101  (e.g., an embodiment of controller  130 ), the operational state of mobile structure  101  based, at least in part, on the set of potential navigation hazard contacts determined in block  1604 , the corresponding set of hazard priorities determined in block  1606 , and a preselected minimum priority threshold. In some embodiments, such operational state of mobile structure  101  may include a target heading, speed, and/or route for mobile structure  101 , and controller  130  may be configured to adjust the operational state of mobile structure  101  by adjusting the target heading, speed, and/or route for mobile structure  101  to avoid one or more potential navigation hazard contacts with corresponding hazard priorities above the preselected minimum priority threshold. 
     In additional or alternative embodiments, where the passage database comprises a fishing compendium, controller  130  may be configured to adjust a target heading, speed, and/or route for mobile structure  101  to navigate to one or more potential fishing spots with corresponding fishing location priorities above a preselected minimum fishing priority threshold. 
     Embodiments of the present disclosure can thus provide reliable and accurate AR display views for mobile structures and/or passage planning systems. Such embodiments may be used to assist in the operation of various systems, devices, and/or sensors coupled to or associated with mobile structure  101 , such as navigation control system  190  in  FIG. 1A , as described herein. Moreover, such embodiments may be employed to reliably and accurately provide situational awareness and collision detection and avoidance, as described herein. 
     Where applicable, various embodiments provided by the present disclosure can be implemented using hardware, software, or combinations of hardware and software. Also, where applicable, the various hardware components and/or software components set forth herein can be combined into composite components comprising software, hardware, and/or both without departing from the spirit of the present disclosure. Where applicable, the various hardware components and/or software components set forth herein can be separated into sub-components comprising software, hardware, or both without departing from the spirit of the present disclosure. In addition, where applicable, it is contemplated that software components can be implemented as hardware components, and vice-versa. 
     Software in accordance with the present disclosure, such as non-transitory instructions, program code, and/or data, can be stored on one or more non-transitory machine readable mediums. It is also contemplated that software identified herein can be implemented using one or more general purpose or specific purpose computers and/or computer systems, networked and/or otherwise. Where applicable, the ordering of various steps described herein can be changed, combined into composite steps, and/or separated into sub-steps to provide features described herein. 
     Embodiments described above illustrate but do not limit the invention. It should also be understood that numerous modifications and variations are possible in accordance with the principles of the invention. Accordingly, the scope of the invention is defined only by the following claims.