Autopilot autorelease systems and methods

Techniques are disclosed for systems and methods to provide accurate, low lag, and reliable autopilot autorelease in a hydraulic steering system for mobile structures. A hydraulic steering system includes a logic device configured to communicate with an autopilot pump controller, a control surface reference sensor, an orientation sensor, and/or a gyroscope. Control and sensor signals provided by the pump controller and/or the various sensors are used to selectively enable and/or disable an autopilot release signal. The autopilot release signal enables or disables the autopilot pump controller and/or an autopilot pump, or controls the autopilot pump controller to enable or disable the autopilot pump.

TECHNICAL FIELD

One or more embodiments of the invention relate generally to an autopilot control and more particularly, for example, to systems and methods for disabling a hydraulically actuated autopilot for mobile structures.

BACKGROUND

Hydraulically actuated steering systems typically include a yoke or helm pump that actuates a steering cylinder used to change the position of a corresponding control surface, such as a rudder or actuated propulsion system on a ship or various control surfaces on an airplane. Conventional autopilot installations for hydraulic steering systems include a motorized autopilot pump and a reference transducer or sensor coupled to the steering cylinder and/or steering control surface to provide steering angle/position feedback to the autopilot controller.

Most conventional autopilots are enabled and disabled through manipulation of a keypad containing “auto” and “standby” buttons, where a user must manually disable the autopilot before being able to steer the corresponding vehicle without being fought by the autopilot. Other types of conventional autopilots require a user to overpower the autopilot before the autopilot disengages, but this technique is typically unavailable in hydraulic steering systems because the helm pump cannot easily overpower the autopilot pump when they are coupled in parallel, as is typical with hydraulic steering systems with integrated hydraulically actuated autopilots. Moreover, any substantial delay (e.g., to find and push a “standby” button and/or to spin a helm faster than an autopilot can pump against) risks collision with an object in the path of the mobile structure. Thus, there is a need for an improved methodology to provide expedient, accurate, and reliable release of an hydraulically actuated autopilot for a mobile structure.

SUMMARY

Techniques are disclosed for systems and methods to provide accurate, low lag, and reliable autopilot release in a hydraulic steering system for mobile structures. In one embodiment, a hydraulic steering system may include a logic device configured to communicate with an autopilot pump controller, a control surface reference sensor, an orientation sensor, and/or a gyroscope. Control and sensor signals provided by the pump controller and/or the various sensors may be used to selectively enable and/or disable an autopilot release signal. The autopilot release signal may be configured to enable or disable the autopilot pump controller and/or an autopilot pump, or control the autopilot pump controller to enable or disable the autopilot pump.

In various embodiments, a system may include a logic device configured to configured to receive one or more sensor and/or control signals and provide an autopilot release signal for a hydraulic steering system coupled to a mobile structure. In some embodiments, the logic device may be adapted to receive control surface angles and autopilot control surface demands corresponding to a control surface for the mobile structure that is actuated by the hydraulic steering system; and selectively enable the autopilot release signal based, at least in part, on the control surface angles and/or the autopilot control surface demands.

In some embodiments, a method may include receiving control surface angles and autopilot control surface demands corresponding to a control surface for a mobile structure that is actuated by a hydraulic steering system; and selectively enabling the autopilot release signal based, at least in part, on the control surface angles and/or the autopilot control surface demands. In some embodiments, the method may include determining a control surface speed from the control surface angles; determining an autopilot control surface rate from the autopilot control surface demands; and selectively enabling the autopilot release signal based, at least in part, on the control surface speed and the autopilot control surface rate.

In some embodiments, a system may include a logic device configured to receive one or more sensor and/or control signals and provide an autopilot release signal for a hydraulic steering system coupled to a mobile structure. The logic device may be configured to initiate an autorelease observation cycle based, at least in part, on control surface angles and autopilot control surface demands corresponding to a control surface for the mobile structure that is actuated by the hydraulic steering system; and selectively enable the autopilot release signal during the autorelease observation cycle based, at least in part, on the control surface angles and/or the autopilot control surface demands corresponding to the initiated autorelease observation cycle.

In some embodiments, a method may include initiating an autorelease observation cycle based, at least in part, on control surface angles and autopilot control surface demands corresponding to a control surface for mobile structure that is actuated by a hydraulic steering system coupled to the mobile structure; and selectively enabling the autopilot release signal during the autorelease observation cycle based, at least in part, on the control surface angles and/or the autopilot control surface demands corresponding to the initiated autorelease observation cycle.

DETAILED DESCRIPTION

In accordance with various embodiments of the present disclosure, hydraulic steering systems and methods may advantageously be configured to generate an autopilot autorelease signal to deactivate the autopilot automatically without requiring additional helm sensors. Such systems and methods may include an autopilot/hydraulic pump controller in conjunction with a gyroscope and/or a heading sensor providing measurements of a yaw rate and/or a heading of a mobile structure. For example, the gyroscope and/or heading sensor may be mounted to or within the mobile structure (e.g., an aircraft, watercraft, and/or other steered mobile structure), or may be integrated with the autopilot/hydraulic pump controller. Embodiments of the present disclosure can reliably enable and disable an autopilot autorelease signal using hydraulic pump control signals and, in some embodiments, a yaw rate of the mobile structure. In some embodiments, such systems and methods may be used to enable and/or disable an autopilot autorelease signal without input from a control surface reference transducer/sensor (e.g., a rudder reference transducer).

Often, hydraulically steered mobile structures, such as boats, include a helm station, an autopilot pump, and a hydraulic cylinder (connected to a rudder or outboard engine) that are connected in parallel. Both the helm pump and the autopilot pump may include check valves so they cannot be backdriven. This means that if either or both the helm/pilot pumps run, then the cylinder will respond. Many boats of this type are fitted with a rudder reference sensor which provides the autopilot with precise rudder angle information, and gives user feedback via a rudder angle indicator. In the case where the skipper needs to make a course adjustment, or avoid an obstacle, it is desirable to eliminate the step of having to press standby.

If the skipper attempts to move the helm without entering standby, then the autopilot will run in the direction opposite the manually applied helm because the autopilot will try to regain the original course. This will not create mechanical damage: some of the oil pumped by the skipper through the helm pump will simply be diverted into the autopilot pump rather than reaching the cylinder. However it will hamper the skipper's attempt to avoid an obstacle, and so it is desirable to automatically ‘release’ the autopilot.

To create the autopilot release signal, a system may first measure the rate of change of rudder angle by differentiation. Optionally a linear filter (e.g., with a 0.5 s time constant) may be applied, along with a deadband filter, to eliminate noise. The same filter and deadband may be applied to an autopilot pump motor speed signal (or drive signal, or a rudder demand, if a speed signal or drive signal is not available). After such processing, there are two resulting signals, the measured rudder speed and the autopilot's intended rudder rate. The autopilot release signal may be asserted if the intended rudder rate is zero and the measured rudder speed is non-zero for more than a predetermined time period (e.g., 0.5 s), or if the mathematical signs of the measured and applied signals are different for more than the predetermined time period, for example.

Once the autopilot release signal is enabled, the intended rudder rate will be zero by definition (e.g., the autopilot will no longer be driving or active). The autopilot release signal may be cleared if the measured rudder speed is zero for more than a period of time (e.g., 2 or 10 seconds, corresponding to an estimated comfortable time lag once the skipper stops applying helm inputs) and/or once the heading has stabilized (e.g., the yaw rate falls below a predetermined threshold, such as 2°/s). Various permutations, thresholds, and time periods are contemplated. In some embodiments, one or more such control loop parameters may be adjusted adaptively to a particular type of mobile structure and/or range of environmental conditions.

In an embodiment of the present disclosure, a reliable virtual rudder estimate may be determined without resorting to a steering actuator/control surface reference transducer/sensor by estimating the hydraulic slip from other sensor and/or control signals and deriving the virtual rudder estimate from the hydraulic slip. A “virtual rudder” or a “virtual rudder estimate,” as used herein, is an estimated steering angle/position that may be used by an autopilot or other type of controller of a steering system, for example, to steer a mobile structure according to a desired heading.

FIG. 1illustrates a block diagram of a system100including a hydraulic steering system150in accordance with an embodiment of the disclosure. In various embodiments, system100may be adapted to receive one or more signals corresponding to control surface angles (e.g., rudder angles), autopilot control surface demands (e.g., rudder demands), and/or corresponding angular velocities (e.g., yaw rates) for mobile structure101, for example, and selectively enable and/or disable an autopilot release signal based on the one or more signals.

In further embodiments, system100may be adapted to detect a hydraulic pump drive signal of hydraulic steering system150and/or to measure a yaw rate of mobile structure101. System100may then use these detections/measurements to determine a linear steering actuator speed (e.g., a linear rudder speed) for mobile structure101and/or an elasticity estimate for hydraulic steering system150. System100may determine a corrected steering actuator speed from the linear steering actuator speed and/or the elasticity estimate, and then derive a virtual rudder estimate from the corrected steering actuator speed. In various embodiments, system100may use the virtual rudder estimate to control hydraulic steering system150and steer mobile structure101according to a desired heading, such as heading angle107, for example. In another embodiment, hydraulic steering system may also use rudder reference transducer to provide a rudder reference measurement.

In the embodiment shown inFIG. 1, system100may be implemented to provide hydraulically actuated autopilot control for a particular type of mobile structure101, such as an aerial drone, a watercraft, an airplane, a vehicle, and/or other types of mobile structures. In one embodiment, system100may include one or more of a user interface120, a controller130, an orientation sensor140, a speed sensor142, a gyroscope/accelerometer144, a global positioning satellite system (GPS)146, a hydraulic steering system150, a propulsion system170, and one or more other sensors and/or actuators, such as other modules180. In some embodiments, one or more of the elements of system100may be implemented in a combined housing or structure that can be coupled to mobile structure101and/or held or carried by a user of mobile structure101.

Directions102,103, and104describe one possible coordinate frame of mobile structure101(e.g., for headings or orientations measured by orientation sensor140and/or angular velocities and accelerations measured by gyroscope/accelerometer144). As shown inFIG. 1, direction102illustrates a direction that may be substantially parallel to and/or aligned with a longitudinal axis of mobile structure101, direction103illustrates a direction that may be substantially parallel to and/or aligned with a lateral axis of mobile structure101, and direction104illustrates a direction that may be substantially parallel to and/or aligned with a vertical axis of mobile structure101, as described herein. For example, a roll component of motion of mobile structure101may correspond to rotations around direction102, a pitch component may correspond to rotations around direction103, and a yaw component may correspond to rotations around direction104.

Heading angle107may correspond to the angle between a projection of a reference direction106(e.g., the local component of the Earth's magnetic field) onto a horizontal plane (e.g., referenced to a gravitationally defined “down” vector local to mobile structure101) and a projection of direction102onto the same horizontal plane. In some embodiments, the projection of reference direction106onto 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 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 structure101.

User interface120may be implemented as a display, a touch screen, a keyboard, a mouse, a joystick, a knob, a steering wheel, a ship's wheel or helm, a yolk, and/or any other device capable of accepting user input and/or providing feedback to a user. In various embodiments, user interface120may be adapted to provide user input (e.g., as a type of signal and/or sensor information) to other devices of system100, such as controller130. User interface120may 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 interface120may 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 corrected steering actuator speeds and/or virtual rudder estimates, 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.

In various embodiments, user interface120may 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 system100and devices within system100. Once user interface120accepts a user input, the user input may be transmitted to other devices of system100over one or more communication links.

In one embodiment, user interface120may be adapted to receive a sensor or control signal (e.g., from orientation sensor140and/or hydraulic steering system150) over communication links formed by one or more associated logic devices, for example, and display sensor information corresponding to the received sensor or control signal to a user. In related embodiments, user interface120may be adapted to process sensor and/or control signals to determine sensor information. For example, a sensor signal may include a heading, an angular velocity, an acceleration, and/or a position of mobile structure101. In such embodiment, user interface120may be adapted to process the sensor signals to determine sensor information indicating a motion compensated/stabilized linear acceleration, a roll, pitch, and/or yaw (orientation and/or rate), and/or a position of mobile structure101, for example, and display the sensor information as feedback to a user. In one embodiment, user interface120may 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. For example, user interface120may be adapted to display a time series of positions of mobile structure101overlaid on a geographical map, which may include one or more graphs indicating a corresponding time series of virtual rudder estimates, pump control signals, and/or other sensor and/or control signals.

In some embodiments, user interface120may be adapted to accept user input including a user-defined target heading (e.g., a locked heading) for mobile structure101, for example, and to generate control signals for hydraulic steering system150to cause mobile structure101to steer according to the target heading. More generally, user interface120may 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 system100, for instance, for display and/or further processing.

Controller130may 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 hydraulic steering system150, mobile structure101, and/or system100, for example. Such software instructions may also implement methods for processing sensor signals, determining sensor information, providing user feedback (e.g., through user interface120), 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 system100).

In addition, a machine readable medium may be provided for storing non-transitory instructions for loading into and execution by controller130. In these and other embodiments, controller130may 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 system100. For example, controller130may 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 interface120. In some embodiments, controller130may be integrated with one or more user interfaces (e.g., user interface120), and, in one embodiment, may share a communication module or modules. As noted herein, controller130may be adapted to execute one or more control loops for steering control (e.g., using hydraulic steering system150) and/or performing other various operations of mobile structure101and/or system100. 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 structure101and/or system100.

Orientation sensor140may be implemented as one or more of a compass, float, accelerometer, and/or other device capable of measuring an orientation of mobile structure101(e.g., magnitude and direction of roll, pitch, and/or yaw, relative to one or more reference orientations such a gravity and/or Magnetic North) and providing such measurements as sensor signals that may be communicated to various devices of system100. In some embodiments, orientation sensor140may be adapted to provide heading measurements for mobile structure101. In other embodiments, orientation sensor140may be adapted to provide roll, pitch, and/or yaw rates for mobile structure101(e.g., using a time series of orientation measurements). Orientation sensor140may be positioned and/or adapted to make orientation measurements in relation to a particular coordinate frame of mobile structure101, for example.

Speed sensor142may be implemented as an electronic pitot tube, metered gear or wheel, water speed sensor, wind speed sensor, and/or other device capable of measuring a linear speed of mobile structure101(e.g., in a surrounding medium and/or aligned with a longitudinal axis of mobile structure101) and providing such measurements as sensor signals that may be communicated to various devices of system100.

Gyroscope/accelerometer144may be implemented as one or more electronic sextants, semiconductor devices, integrated chips, accelerometer sensors, accelerometer sensor systems, or other devices capable of measuring linear accelerations and/or angular velocities/accelerations (e.g., direction and magnitude) of mobile structure101and providing such measurements as sensor signals that may be communicated to other devices of system100(e.g., user interface114, controller130). Gyroscope/accelerometer144may be positioned and/or adapted to make such measurements in relation to a particular coordinate frame of mobile structure101, for example.

GPS146may be implemented as a global positioning satellite receiver and/or other device capable of determining absolute and/or relative position of mobile structure101based 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 system100. In some embodiments, GPS146may be adapted to determine a velocity of mobile structure101(e.g., using a time series of position measurements), such as an absolute velocity of mobile structure101. In various embodiments, one or more logic devices of system100may be adapted to determine a speed of mobile structure101from such velocity.

Hydraulic steering system150may be adapted to physically adjust a heading of mobile structure101according to one or more control signals, user inputs, and/or a virtual rudder estimate provided by logic device of system100, such as controller130. Hydraulic steering system150may include one or more reversing pumps, pump controllers, hydraulic actuators (e.g., steering cylinders), and at least one control surface (e.g., a rudder or other type of steering mechanism) of mobile structure101physically coupled to at least one hydraulic actuator. In some embodiments, hydraulic system150may be adapted to physically adjust a control surface of mobile structure101to a variety of positive and/or negative steering angles/positions. One or more embodiments of hydraulic steering system150are illustrated in more detail inFIGS. 2 and 3.

Propulsion system170may be implemented as a propeller, turbine, or other thrust-based propulsion system, and/or other types of propulsion systems that can be used to provide motive force to mobile structure101. In some embodiments, propulsion system170may be non-articulated, for example, such that the direction of thrust generated by propulsion system170is fixed relative to a coordinate frame of mobile structure101. 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 system170may be articulated and coupled to and/or integrated with hydraulic steering system150, for example, such that the direction of generated thrust is variable relative to a coordinate frame of mobile structure101, and such that propulsion system170forms a control surface or part of a control surface, as described herein. 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), or an aircraft propeller or turbine with a variable thrust vector, for example. As noted herein, both articulated and non-articulated propulsion systems can produce an assisting force on a steering actuator of hydraulic steering system150that varies with thrust. Propulsion system170is illustrated in more detail inFIGS. 2 and 3.

Other modules180may include other and/or additional sensors, actuators, communications modules/nodes, and/or user interface devices used to provide additional environmental information of mobile structure101, for example. In some embodiments, other modules180may 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 system200(e.g., controller130) to provide operational control of mobile structure101that 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 structure101, for example.

In general, each of the elements of system100may 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 a method for providing hydraulic steering, for example, or for transmitting and/or receiving communications, such as sensor signals, sensor information, and/or control signals, between one or more devices of system100. In one embodiment, such method may include instructions to determine reference direction106, heading107, and/or a yaw rate of mobile structure101from various sensor signals, to determine an elasticity estimate for hydraulic steering system150, and/or to determine a virtual rudder estimate from the elasticity estimate and one or more sensor and/or control signals, for example, as described herein. In a further embodiment, such method may include instructions for forming one or more communication links between various devices of system100.

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 system100. 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), 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 system100may 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, and/or other analog and/or digital components enabling each of the devices of system100to transmit and/or receive signals, for example, in order to facilitate wired and/or wireless communications between one or more devices of system100. Such components may be integrated with a corresponding element of system100, 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 system100using a variety of wired and/or wireless communication techniques, including voltage signaling, Ethernet, WiFi, Bluetooth, Zigbee, Xbee, Micronet, or other medium and/or short range wired and/or wireless networking protocols and/or implementations, for example. In such embodiments, each element of system100may 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 system100may 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, and/or timing errors between the various measurements of magnetic fields and accelerations. For example, orientation sensor140, gyroscope/accelerometer144, and controller130may 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 system100may include one or more batteries or other electrical power storage devices, for example, and may include one or more solar cells 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 system100). In some embodiments, one or more of the devices may be powered by a power source for mobile structure101, using one or more power leads.

In various embodiments, a logic device of system100(e.g., of orientation sensor140, gyroscope/accelerometer144, and/or other elements of system100) may be adapted to determine parameters (e.g., using signals from various devices of system100) for transforming a coordinate frame of orientation sensor140and/or gyroscope/accelerometer144to/from a coordinate frame of mobile structure101, at-rest and/or in-motion, and/or other coordinate frames, as described herein. One or more logic devices of system100may be adapted to use such parameters to transform a coordinate frame of gyroscope/accelerometer144to/from a coordinate frame of orientation sensor140and/or mobile structure101, for example. Furthermore, such parameters may be used to determine and/or calculate one or more adjustments to an orientation of gyroscope/accelerometer144that would be necessary to physically align a coordinate frame of gyroscope/accelerometer144with a coordinate frame of orientation sensor140and/or mobile structure101. Adjustments determined from such parameters may be used to selectively power adjustment servos (e.g., of gyroscope/accelerometer144and/or other elements of system100), for example, or may be communicated to a user through user interface120, as described herein.

FIG. 2illustrates a diagram of a hydraulic steering system200in accordance with an embodiment of the disclosure. In the embodiment shown inFIG. 2, system200may be implemented to provide hydraulically actuated autopilot control for mobile structure101, similar to system100ofFIG. 1. For example, system200may include sensor cluster240(e.g., orientation sensor140, gyroscope/accelerometer144, GPS146), user interface/controller120/130, secondary user interface120, hydraulic steering system150, and various other sensors and/or actuators. In the embodiment illustrated byFIG. 2, mobile structure101is implemented as a motorized boat including a hull210, a deck212, a mast/sensor mount214, a rudder post, a rudder266, and inboard motor170. In other embodiments, hull210, deck212, mast/sensor mount214, rudder post265, rudder266, and inboard motor170may 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, and/or other portions of a vehicle.

As depicted inFIG. 2, mobile structure101includes rudder266that is coupled to hydraulic steering system150through rudder post265and non-articulated inboard motor170that is coupled directly to mobile structure101. If inboard motor170produces propeller walk rotating mobile structure101counterclockwise (looking down on deck212), rudder266experiences an assisting force from starboard to port such that turns to port are assisted. Counterclockwise rotations result in starboard turns being assisted. If motor170was instead mounted to rudder post265, the propeller walk that produced counterclockwise rotation of mobile structure101when inboard would instead produce counterclockwise rotation of rudder post265and assist starboard turns. In some embodiments, controller130may be configured to determine both the magnitude and direction of an assisting force without user intervention/input (e.g., without knowledge of the type of propulsion system) and/or without a reference transducer/sensor, for example, by executing the various methods described herein.

In one embodiment, user interfaces120may be mounted to mobile structure101substantially on deck212and/or mast/sensor mount214. Such mounts may be fixed, for example, or may include gimbals and other leveling mechanisms so that a display of user interfaces120stays substantially level with respect to a horizon and/or a “down” vector. In another embodiment, at least one of user interfaces120may be located in proximity to mobile structure101and be mobile throughout a user level (e.g., deck212) of mobile structure101. For example, secondary user interface120may be implemented with a lanyard and/or other type of strap and/or attachment device and be physically coupled to a user of mobile structure101so as to be in proximity to mobile structure101. In various embodiments, user interfaces120may 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 inFIG. 2, in some embodiments, speed sensor142may be mounted to a portion of mobile structure101substantially below a typical user level, such as to hull210, and be adapted to measure a relative water speed. Speed sensor142may be adapted to provide a thin profile to reduce and/or avoid water drag. Speed sensor142may 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 sensor142may be powered by a power source for mobile structure101, for example, using one or more power leads penetrating hull210.

In the embodiment illustrated byFIG. 2, mobile structure101includes direction/longitudinal axis102, direction/lateral axis103, and direction/vertical axis104meeting approximately at mast/sensor mount214(e.g., near a center of gravity of mobile structure101). In one embodiment, the various axes may define a coordinate frame of mobile structure101and/or sensor cluster240. 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 system200and/or mobile structure101. Each element of system200may be located at positions different from those depicted inFIG. 2. Each device of system200may include one or more batteries or other electrical power storage devices, for example, and may include one or more solar cells or other electrical power generating devices. In some embodiments, one or more of the devices may be powered by a power source for mobile structure101. As noted herein, each element of system200may 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 system200. Further, a logic device of that element may be adapted to perform any of the methods described herein.

FIG. 3illustrates a diagram of hydraulic steering system350in accordance with an embodiment of the disclosure. In the embodiment shown inFIG. 3, system350may be implemented to provide hydraulically actuated autopilot control for a mobile structure, similar to system150ofFIGS. 1 and 2. For example, system350may include user interface or helm120coupled to and controlling helm pump352, pump controller355coupled to autopilot pump356, and steering actuator/cylinder360coupled to helm pump352and autopilot pump356through supply lines354. Helm120may be configured to operate helm pump352according to user input (e.g., manually turning a steering wheel or helm), for example, and pump controller355may be configured to operate autopilot pump356according to pump control signals (e.g., provided by controller130ofFIG. 1). Steering cylinder360may be coupled to articulated propulsion system170through tiller assembly367and rudder post265, such that motion of cylinder body361from right to left on the page results in propulsion system170rotating clockwise.

As shown inFIG. 3, steering actuator360is implemented as a balanced hydraulic actuator, where cylinder rod362extends all the way through cylinder body361and there is no volume or area imbalance when pumping fluid into either end of cylinder body361. In other embodiments, steering actuator360may be implemented as an unbalanced hydraulic actuator, where cylinder rod362extends from sliding seal363through only one end of cylinder body361. Also shown are anchors364, which may be configured to anchor cylinder rod362, provide firm actuation through movement of cylinder body361, and/or act as port and starboard end stops limiting motion of cylinder body361and steering actuator360, thereby limiting motion of propulsion system170.

Although a particular configuration of steering actuator, tiller assembly, and control surface are depicted inFIG. 3, system350may be implemented with a variety of different configurations and/or combinations of configurations, including where propulsion system170is replaced with a rudder, for example, or cylinder body361is anchored and cylinder rod362is coupled to rudder post265. Also, in some embodiments, additional helm and/or other pumps may be coupled in parallel to system350without substantially altering operation of system350.

Pumps352and356may be implemented as conventional manual and/or motorized hydraulic pumps with respective check valve assemblies358and359that allow the pumps to be refilled from the low pressure side and/or reservoir357when pumping fluid out of the high pressure side, but do not allow fluid to enter or exit a pump unless the pump is actively pumping and creating a sufficient pressure differential. Thus, pumps352and356are functionally decoupled from each other and do not force each other to rotate when only one pump is operated.

Pump controller355may be implemented as one or more power switching circuits (e.g., power transistors, relays, and/or other power switching circuits), motor sensors, and/or logic devices that can operate autopilot pump356according to various pump control signals (e.g., pulse width modulations or PWMs) indicating a target motor speed, direction, and duration, that can sense a supply voltage, a terminal voltage, and an actual motor speed, and/or that can determine a back EMF and/or a motor load of autopilot pump356, as described herein. In some embodiments, pump controller355may be configured to communicate with an external controller (e.g., controller130ofFIG. 1) and receive pump control signals indicating direction, duration, and/or amplitude of pump control signals to be provided to a motor for autopilot pump356. Motor sensors of pump controller355may include one or more current sensors, voltage sensors, RPM sensors, temperature sensors, and/or other motor sensors, for example, and can be referenced to various terminals of a pump motor including individual winding terminals. As noted herein, each element of system350, and particularly pump controller355, 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 system350and systems100and/or200ofFIGS. 1 and 2. Further, a logic device of that element may be adapted to perform any of the methods described herein.

Also shown inFIG. 3is the direction of propeller walk (left to right), the resulting assisting force (right to left on cylinder body361), and the resulting expanded air volume368and compressed air volume369. In the configuration shown inFIG. 3, pumping fluid into the B side of the system acts against the assisting force, and pumping fluid into the A side of the system acts with the assisting force.

When pumping fluid into the B side of system350, steering actuator360may produce a response that can be reliably estimated by determining the corresponding linear steering actuator speed (e.g., rudder speed) from the applicable linear hydraulic slip contributions (e.g., the load and speed based linear slip rate and any system directional imbalance linear slip rate) that may be derived from pump control signals provided to autopilot pump356and/or pump sensor signals indicating supply voltage, back EMF, and/or pump speed. In some embodiments, the load and speed based linear slip rate of autopilot pump356is substantially constant over the steering actuator positions and operations caused by pump controller355, regardless of a speed of the mobile structure and/or assisting forces on steering actuator360. In such embodiments, the linear steering actuator speed may be derived from pump control signals.

When pumping fluid into the A side of system350, steering actuator360may produce a response that can be reliably estimated by determining the corresponding linear steering actuator speed, estimating the elasticity of system350that may depend partially on a measured yaw rate of a coupled mobile structure (e.g., from gyroscope/accelerometer144ofFIG. 1), and then determining a corrected linear steering actuator speed from the estimated elasticity and the linear steering actuator speed, as described herein. In some embodiments, the linear steering actuator speed may be properly corrected using the estimated elasticity by ratcheting the response of the estimated elasticity in accordance with the action of check valve assembly359, as described herein. For example, a controller (e.g., controller130) may be configured to determine a ratchet balancing component based on a pump control signal (e.g., provided by pump controller355) and the elasticity estimate, where the ratchet balancing component corresponds to an expansion and/or compression of a volume of air in system350that is approximately equal to the magnitude of the elasticity estimate, the expansion takes place over a relatively short period of time, the compression takes place over a relatively long period of time, and the various periods of time correspond roughly to the actual elasticity response in system350. As such, the ratchet balancing component may be configured to compensate for the elastic response of system350to one or more pump control signals provided by pump controller355.

In various embodiments, the estimated elasticity of system350may be adaptive with respect to a measured response of system350and a coupled mobile structure. For example, a controller may be configured to determine a virtual rudder error from a prior virtual rudder estimate (e.g., derived from a prior elasticity estimate) and, in some embodiments, a yaw rate of the coupled mobile structure. In such embodiments, the elasticity estimate may be determined from the virtual rudder error and the measured yaw rate, which helps drive the elasticity estimate towards a value that is reliably representative of the response of system350.

FIG. 4illustrates a flow diagram of process400to provide autopilot autorelease in a hydraulic steering system for mobile structure101in accordance with embodiments of the disclosure. In some embodiments, the operations ofFIG. 4may be implemented as software instructions executed by one or more logic devices associated with corresponding electronic devices and/or sensors of system100ofFIG. 1, system200ofFIG. 2, and/or system350ofFIG. 3. More generally, the operations ofFIG. 4may be implemented with any combination of software instructions and/or electronic hardware (e.g., inductors, capacitors, amplifiers, or other analog and/or digital components).

It should be appreciated that any step, sub-step, sub-process, or block of process400may be performed in an order or arrangement different from the embodiments illustrated byFIG. 4. For example, in other embodiments, one or more blocks may be omitted from 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 of systems100,200, and/or350prior to moving to a following portion of a corresponding process. Although process400is described with reference to systems100,200, and350, process400may be performed by other systems different from systems100,200, and350and including a different selection of electronic devices, sensors, mobile structures, and/or mobile structure attributes.

In block402, a logic device receives control surface angles, autopilot control surface demands, and/or angular velocities for a mobile structure. For example, controller130may be configured to receive one or more control surface angles (e.g., a measurement of an orientation of rudder266and/or an articulated version of propulsion system170) from steering sensor/actuator150(e.g., separate from, or integrated with propulsion system170), an autopilot control surface demand (e.g., a pump control signal and/or a pump sensor signal corresponding to autopilot pump controller355and/or autopilot pump356) from controller130and/or autopilot pump controller355, and/or an angular velocity corresponding to a direction of motion for mobile structure101generated by the control surface (e.g., a yaw rate corresponding to the yaw for mobile structure101generated by rudder266) from orientation sensor140and/or gyroscope/accelerometer144.

In some embodiments, controller130may be configured to receive various pump control and/or sensor signals, for example, and determine virtual control surface estimates based, at least in part, on the signals. For example, controller130may be implemented and/or operated to determine such virtual control surface estimates (e.g., virtual rudder estimates, in one embodiment) using any one or combination of systems and/or methods described in U.S. patent application Ser. No. 15/222,905 filed Jul. 28, 2016 and entitled “HYDRAULIC SLIP COMPENSATION SYSTEMS AND METHODS”, which is hereby incorporated by reference in its entirety. In such embodiments, controller130may be configured to use the virtual control surface estimates as the control surface angles.

In block404, a logic device determines a control surface speed, an autopilot control surface rate, and/or and angular stability for the mobile structure. For example, controller130may be configured to determine the control surface speed from the control surface angles provided in block402, and likewise the autopilot control surface rate from the autopilot control surface demands, and the angular stability from the angular velocities provided in block402.

In embodiments where the control surface angles are provided by steering sensor/actuator150(e.g., separate from, or integrated with propulsion system170) and/or are determined virtual control surface estimates, for example, controller130may be configured to determine the control surface speed by differentiating the control surface angles. In some embodiments, the sensor measurements and/or estimates may be filtered and/or otherwise processed (e.g., a hysteresis filter may be applied) to reduce or eliminate noise in the measurements and/or estimates. In other embodiments, the speed may be filtered and/or processed to reduce noise in the speed.

In embodiments where the autopilot control surface demands correspond to pump control signals, for example, controller130may be configured to determine the autopilot control surface rate by differentiating the pump control signals. For instance, an autopilot control surface demand may correspond to the difference and/or error between a target heading and a measured heading for mobile structure101. A corresponding pump control signal may include the error and/or other digital and/or analog signals corresponding to the error, for example. In various embodiments, controller130may be configured to determine the control surface demand using any one or combination of systems and/or methods described in U.S. patent application Ser. No. 15/239,760 filed Aug. 17, 2016 and entitled “ACCELERATION CORRECTED ATTITUDE ESTIMATION SYSTEMS AND METHODS”, U.S. Provisional Patent Application No. 62/099,022 filed Dec. 31, 2014 and entitled “STABILIZED DIRECTIONAL CONTROL SYSTEMS AND METHODS”, U.S. Provisional Patent Application No. 62/099,016 filed Dec. 31, 2014 and entitled “ADAPTIVE TRACK KEEPING SYSTEMS AND METHODS”, and/or U.S. Provisional Patent Application No. 62/099,032 filed Dec. 31, 2014 and entitled “PROACTIVE DIRECTIONAL CONTROL SYSTEMS AND METHODS”, which are hereby incorporated by reference in their entirety.

In embodiments where the autopilot control surface demands correspond to pump sensor signals, such as PWM signals and/or other power signals corresponding to autopilot pump controller355and/or autopilot pump356, for example, controller130may be configured to determine the autopilot control surface rate by determining a value for the pump sensor signals. For instance, a PWM signal may correspond to a positive or negative signal (e.g., a forward or reverse pump motion), and may include an amplitude, pulse width, and/or pulse rate corresponding to an autopilot control surface rate (e.g., where the rate of the pump is roughly directly proportional to the desired rate of change in orientation of the control surface).

In various embodiments, controller130may be configured to determine the angular stability based on the angular velocities provided in block402. For example, controller130may be configured to compare the magnitude of one or more angular velocities to a predetermined threshold, which may be factory set, user-supplied, and/or adaptively determined and/or adjusted to differentiate motion of mobile structure101due to user intervention from typical and/or actual environmental conditions. In such embodiments, the angular stability may be implemented as a binary state variable where mobile structure101is considered stable if the one or more angular velocities are less than or equal to one or more corresponding predetermined thresholds.

In block406, a logic device selectively enables an autopilot release signal. For example, controller130may be configured to selectively enable an autopilot release signal and/or provide the autopilot release signal to autopilot controller355and/or another device (e.g., a switch) configured to electrically decouple autopilot pump356and/or autopilot pump controller355from power and/or various pump control signals. In some embodiments, controller130may be configured to monitor the autopilot release signal and control itself to discontinue providing pump control signals and/or power to autopilot pump355accordingly.

In one embodiment, controller130may be configured to determine a product of the control surface speed and the autopilot control surface rate. Such product indicates when the polarities of the speed and the rate are different (e.g., they are fighting each other) and/or when one or both are zero. For example, the autopilot control surface rate is necessarily zero while the autopilot release signal is enabled, and this state can be used to automatically determine when to disable the autopilot release signal, as discussed in block410.

In another embodiment, controller130may be configured to determine that the control surface speed is non-zero or a magnitude of the angular velocity is greater than a predetermined threshold. The first binary state variable indicates whether mobile structure is being actively steered, and the second binary state variable indicates whether mobile structure101is stable, as discussed with respect to block404. If either is true, then controller130may be configured to enable or hold the autopilot release signal since mobile structure101is being actively steered or is unstable enough to require a user at the helm. For example, if the product of the control surface speed and the autopilot control surface rate indicates that a user is fighting the autopilot, or that the autopilot is already effectively disabled by the autopilot release signal, then controller130may continue to enable or assert the autopilot release signal.

Notably, none of the methods to determine the state variables described above require a user to actuate a standby mode button or require a user activity sensor at the helm or helm pump to determine when to enable the autopilot release signal. Furthermore, in embodiments where the control surface angles are determined from virtual control surface estimates and the autopilot control surface demands are determined from pump control signals, no actuator and/or pump sensors are required at all.

In block408, a logic device determines an updated angular stability. For example, controller130may be configured to determine the updated angular stability from one or more updated angular velocities received in a method similar to that described in block402. Furthermore, the angular stability may be determined using a methods similar to that described in block404, such as by comparison of a magnitude of an angular velocity to a predetermined threshold, for example. Such stability may in some embodiments be a prerequisite to disabling the autopilot release signal enabled in block406. In some embodiments, other and/or additional prerequisites to disabling the autopilot release signal may be required. For example, controller130may be configured to determine the control surface speed is substantially zero (e.g., by comparing a filtered and/or low noise control surface speed) before disabling the autopilot release signal.

In block410, a logic device selectively disables the autopilot release signal. For example, controller130may be configured to selectively disable the autopilot release signal based on the angular velocity and/or angular stability received/determined in block402/406. In further embodiments, controller130may be configured to only disable the autopilot release signal when mobile structure101is stable and there is little to no steering input at the control surface (e.g., a user has stopped providing overriding input to a helm pump).

Embodiments of the present disclosure can thus disable, decouple, and/or de-energize autopilot pump356of hydraulic steering system350by comparing an intended autopilot rudder rate with a measured rudder rate to disengage the autopilot pump when the helm is sufficiently disturbed by a user/operator. Such embodiments may be used to automatically release the autopilot on a mobile structure without having to manually activate autopilot standby or risking a partially activated autopilot interfering with urgent steering maneuvers.

It is contemplated that any one or combination of methods to provide autopilot release signals may be performed according to one or more operating contexts of a control loop, for example, such as a startup, learning, running, and/or other type operating context. For example, any portion of process400may proceed back to an initial block and proceed through the corresponding process again to retrieve updated control surface angles, autopilot control surface demands, angular velocities, and/or other sensor and/or control signals, as in a control loop. In one embodiment, controller130may be configured to enable the autopilot release signal and then proceed through multiple passes through process400until the various state variables allow controller130to disable the autopilot release signal, as described herein.

FIG. 5illustrates a flow diagram and/or control loop of process500to provide autopilot autorelease in a hydraulic steering system for mobile structure101in accordance with embodiments of the disclosure. In some embodiments, the operations ofFIG. 5may be implemented as software instructions executed by one or more logic devices associated with corresponding electronic devices and/or sensors of system100ofFIG. 1, system200ofFIG. 2, and/or system350ofFIG. 3. More generally, the operation ofFIG. 5may be implemented with any combination of software instructions and/or electronic hardware (e.g., inductors, capacitors, amplifiers, or other analog and/or digital components).

It should be appreciated that any step, sub-step, sub-process, or block of process500may be performed in an order or arrangement different from the embodiments illustrated byFIG. 5. For example, in other embodiments, one or more blocks and/or elements may be omitted from the various processes, and blocks and/or elements from one process may be included in another process. Furthermore, inputs, outputs, various sensor signals, sensor information, calibration parameters, and/or other operational parameters, constants, state variables or other information may be stored to one or more memories of systems100,200, and/or350prior to moving to a following portion of a corresponding process. Although process500is described with reference to systems100,200, and350, process500may be performed by other systems different from systems100,200, and350and including a different selection of electronic devices, sensors, mobile structures, and/or mobile structure attributes.

As can be seen fromFIG. 5, process500may be configured to accept a variety of inputs510,512,514, and/or516and provide an enabled or disabled autopilot release signal at output570. Each of the input signals may be conditioned (if beneficial) to remove noise and/or to prepare them to be compared against each other in the binary logic portion of process500(e.g., starting at blocks526,532, and542). The comparison portion of process500determines the conditions under which output570is enabled or disabled. In general, S-R Flip-Flop560only allows output570to be enabled if process500detects user influence on a control surface that conflicts with the autopilot control, and S-R Flip-Flop560only allows output570to be subsequently disabled if the conflict subsides and mobile structure becomes stable.

Motor PWM signal510may be implemented as a pump control or sensor signal corresponding to a powered state of autopilot pump356. In various embodiments, motor PWM signal510may be characterized by an amplitude, pulse width, and/or pulse rate, each of which may relate to a pump rate of autopilot pump356, which may be roughly directly proportional to a corresponding autopilot control surface rate (e.g., a desired control surface/rudder speed of rudder266). Rudder demand signal512(e.g., autopilot control surface demand512) may in some embodiments be implemented as a pump control signal corresponding to a desired control surface/rudder position or orientation. As noted herein, rudder demand signal512may also correspond to an error signal or difference between a target heading and a measured heading for mobile structure101. In some embodiments, rudder demand signal512may be filtered by hysteresis block520and differentiated by block521to produce a corresponding autopilot control surface rate at switch block530.

In some embodiments, switch block530may be implemented as a manual switch actuated by a user based on preference for one or the other signal due to the types of noise in the respective signal, for example. In other embodiments, switch block530may be controlled by controller130, for example. In such embodiments, controller130may be configured to select one signal over another based on presence of the signal, noise characteristics of the signal, adaptive learning techniques linking one signal to better response for a particular environmental condition, and/or other criteria. For example, controller130may be configured to select motor PWM510by default and to switch to the other signal if a noise level of motor PWM510passes a predetermined threshold.

Rudder reference measurement514(e.g., control surface angle514) may be implemented as a sensor signal from steering sensor/actuator150and be configured to provide precise rudder angle information through direct measurement. In other embodiments, rudder reference measurement514may be implemented as a virtual rudder estimate based, at least in part, on one or more pump control and/or sensor signals, as described herein. In some embodiments, rudder reference measurement514may be filtered by hysteresis block522and differentiated by block521to produce a corresponding control surface speed at product block540and comparison block532.

Yaw rate516(e.g., angular velocity516) may be implemented as a sensor signal from orientation sensor140and/or gyroscope/accelerometer144. For example, in some embodiments, controller130may be configured to receive a measured yaw rate of mobile structure101from gyroscope/accelerometer144. In further embodiments, controller130may be configured to receive a time series of measured headings of mobile structure101from orientation sensor140, for example, and calculate a yaw rate from the series of measured headings. In various embodiments, yaw rate516may be filtered by block524, converted to a magnitude by block525, and compared to a predetermined threshold (e.g., 3 degrees/second) in block526to produce a corresponding binary state variable indicating, roughly, whether mobile structure101is stable (e.g., the angular velocity is equal to or below the predetermined threshold). More generally, any angular velocity may be processed similarly, but the angular velocity and/or velocities should correspond to the motion or motions generated by actuation of the control surface corresponding to inputs510,512, and514.

At blocks540and542, the autopilot control surface rate is multiplied by the control surface speed and the result is compared to zero to determine if their polarities match (e.g., to determine if a user is attempting to act against the autopilot) or if one or both are zero (e.g., to determine if the autopilot release signal is enabled and/or if the autopilot is disabled or off). Block542may be configured to output logical true if either signal is zero or if their polarities differ.

At blocks532and550, the control surface speed is compared to zero (e.g., block532may be configured to output logical true if the control surface speed is zero) and the result is compare to the stability state of mobile structure101(e.g., block526may be configured to output logical true if mobile structure101is stable/the magnitude of yaw rate516is below a predetermined threshold). And block550may be configured to output logical true only when the control surface speed is zero (e.g., the user and the autopilot are not conflicting) and mobile structure101is stable.

At blocks544,546,554, and556, the two logic states output by respective blocks542and550are filtered biased to zero or logical false to reduce noise and/or false positives in the various input signals and block outputs. If the outputs of either block542or550are consistently true over a time period on the order of seconds, the output or outputs are forwarded to block560.

As shown inFIG. 5, block560may be implemented as a S-R Flip-Flop or latch used to latch and release (e.g., enable or disable) the autopilot release signal provided on output570. In various embodiments, the truth table for block560may be implemented as follows, in the format (S,R:Q): (0,0:Q(n−1)), (0,1:0), (1,0:1), (1,1:0); where Q(n−1) is the previous state (e.g., the latched state) of Q). As a result, in the embodiment shown inFIG. 5, block560only enables output570when S is true and R is false, which equates to the control surface speed being non-zero (e.g., rudder266is in motion) and/or mobile structure101being unstable (e.g., yaw rate516is above a predetermined threshold), and, at the same time, the control surface speed or the autopilot control surface rate being zero (e.g., the autopilot is already disabled) or having different polarities (e.g., conflicting). Furthermore, block560latches the autopilot release signal as enabled and only disables an enabled output570when R is true (e.g., the control surface speed is substantially zero and mobile structure101is stable. Block562terminates an unused logic output of block560.

Output570may in various embodiments be coupled to autopilot pump controller355, for example, and autopilot pump controller355may be configured to discontinue providing pump control signals and/or power to autopilot pump356. In other embodiments, a separate device or switch may be coupled to output570and be configured to electrically decouple autopilot pump controller355and/or autopilot pump356from control signals and/or power. In further embodiments, controller130may be configured to monitor output570and discontinue or pause an autopilot process or system accordingly.

Thus, embodiments of the present disclosure can automatically release an autopilot on a mobile structure without a user having to take the time and distraction to manually activate an autopilot standby button or risk a partially activated autopilot interfering with urgent steering maneuvers. Moreover, various embodiments of the present disclosure may be configured to provide autopilot autorelease with minimal sensor input, including without control surface and/or steering reference sensors, which are typically prone to failure.

In some embodiments, an operation to provide autopilot autorelease may advantageously operate according to multiple autorelease observation cycles while an autopilot is engaged, for example, where each autorelease observation cycle is kept relatively short (e.g., as compared to a continuous process) to limit detrimental effects of signal drift and accumulated error. Such embodiments may be configured substantially to rely on only three updating state inputs (e.g., autopilot motor PWM, autopilot motor speed, and control surface angle, as measured by a control surface reference sensor) and one minimum release threshold (e.g., how much a user expects to turn a helm against an autopilot before an autopilot release signal is generated) configured to substantially eliminate false positive autopilot release signals. By limiting the number of updating state inputs, embodiments provide relatively stable and robust autopilot release signals over a variety of operating conditions.FIGS. 6-9illustrate various processes and control loops that may be used to implement such embodiments.

FIG. 6illustrates a flow diagram and/or control loop of process600to provide autopilot autorelease in a hydraulic steering system for mobile structure101in accordance with embodiments of the disclosure. In some embodiments, the operations ofFIG. 6may be implemented as software instructions executed by one or more logic devices associated with corresponding electronic devices and/or sensors of system100ofFIG. 1, system200ofFIG. 2, and/or system350ofFIG. 3. More generally, the operation ofFIG. 6may be implemented with any combination of software instructions and/or electronic hardware (e.g., inductors, capacitors, amplifiers, or other analog and/or digital components).

It should be appreciated that any step, sub-step, sub-process, or block of process600may be performed in an order or arrangement different from the embodiments illustrated byFIG. 6. For example, in other embodiments, one or more blocks and/or elements may be omitted from the various processes, and blocks and/or elements from one process may be included in another process. Furthermore, inputs, outputs, various sensor signals, sensor information, calibration parameters, and/or other operational parameters, constants, state variables or other information may be stored to one or more memories of systems100,200, and/or350prior to moving to a following portion of a corresponding process. Although process600is described with reference to systems100,200, and350, process600may be performed by other systems different from systems100,200, and350and including a different selection of electronic devices, sensors, mobile structures, and/or mobile structure attributes.

As can be seen fromFIG. 6, process500may be configured to accept a variety of inputs610,612,614, and/or616and provide an enabled or disabled autopilot release signal at output670. At a high level, OR block628is configured to generate a reset signal based on a variety of criteria, including criteria indicative of a user attempting to manually override an operating autopilot. When a reset signal is enabled, thereby signaling the beginning/initialization of an autorelease observation cycle, the actual driven control surface angle (e.g., derived from rudder reference measurement614) and the estimated autopilot driven control surface angle (e.g., derived from autopilot pump speed signal612) are each accumulated over the duration of the autorelease observation cycle and sampled for comparison to each other as part of each iteration of process/control loop600.

Any manual user input occurring during the autorelease observation cycle is evident in the difference between the accumulated actual driven control surface angle and the accumulated estimated autopilot driven control surface angle, provided by comparison/difference node646. Once sufficient manual input is detected in a single autorelease observation cycle to overcome a minimum release threshold, autopilot release signal/output570is enabled. In the embodiment shown inFIG. 6, the current autorelease observation cycle is reset when the autopilot release signal670is enabled, thereby restarting the detection and accumulation processes. Each autorelease observation cycle may include one or multiple iterations of process/control loop600, and the iteration rate is typically limited only by one or more of the update rates of the various inputs, or by a predetermined iteration delay. Common update rates (e.g., iteration rates) for process600are 50 ms, or 200 times per second.

Each of the input signals may be conditioned (if beneficial) to remove noise and/or to prepare them to be compared against each other in other portions of process600(e.g., primarily at blocks44,646,648, and652). The comparison portion of process600determines the conditions under which output570is enabled or disabled during an autorelease observation cycle. In general, comparison block648only allows output570to be enabled if process600detects user influence on a control surface that conflicts with the autopilot control and that is sufficiently above a minimum release threshold (e.g., minimum release threshold616).

Motor PWM signal610(e.g., an autopilot control surface demand) may be implemented as a pump control or sensor signal corresponding to a powered state of autopilot pump356. In various embodiments, motor PWM signal610may be characterized by an amplitude, pulse width, and/or pulse rate, each of which may relate to a pump rate of autopilot pump356, which may be roughly directly proportional to a corresponding autopilot control surface rate (e.g., a desired control surface/rudder speed of rudder266). In general, motor PWM signal610may be used to determine an autopilot pump drive direction and/or a lack of drive (e.g., an autopilot pump drive of approximately zero), as shown in process600.

For example, as shown inFIG. 6, motor PWM signal610may be provided to block622, which may be configured to indicate a positive or negative (starboard or port) drive direction of autopilot pump356. Upon a detected reset, the current autopilot pump drive direction may be latched or stored in block630, and that stored value may be compared to subsequent autopilot pump drive directions at comparison block624in order to detect an autopilot pump drive reversal (e.g., a reversal in direction). Upon such detection, comparison block624may provide a reset signal to OR block628for distribution to blocks617,630,640, and642and, thereby, initialize an autorelease observation cycle.

Motor PWM signal610may also be provided to block620, which may be configured to detect when an autopilot pump drive is approximately zero over a predetermined minimum period of time, such as 1-2 seconds, for example. Upon such detection (e.g., where there is substantially no autopilot activity and the historic drive direction is meaningless), block620may provide a reset signal to OR block628for distribution to blocks617,630,640, and642and, thereby, initialize an autorelease observation cycle.

Upon initialization of an autorelease observation cycle, blocks640,642,644, and646may be configured to accumulate and compare actual driven control surface angles and estimated autopilot driven control surface angles derived from rudder reference measurement614and autopilot pump speed signal612, respectively.

Autopilot pump speed signal612(e.g., an autopilot control surface demand) may in some embodiments be implemented as a pump sensor signal corresponding to a measured speed of autopilot pump356, which may be roughly directly proportional to an estimated driven control surface/rudder speed or rate. For example, autopilot pump speed signal612may be derived from a measured tachometer feedback from autopilot pump356. Such tachometer feedback signal may be measured directly (e.g., though use of an optical detector and marks along a rotating shaft or other portion of autopilot pump356, for example), can be derived from a DC motor back emf (e.g., by momentarily removing power from or “floating” a motor for autopilot pump356, sensing the generated voltage/back emf, and determining a motor speed based on the sensed voltage and/or voltage over time), and/or can be determined through other motor tachometer feedback techniques. In specific embodiments, autopilot pump356may be sampled in such fashion every 40 to 50 milliseconds to determine the corresponding autopilot pump speed signal. In some embodiments, autopilot pump speed signal612may be filtered and/or otherwise processed to produce a corresponding estimated autopilot driven control surface rate at integrator block642. In other embodiments, autopilot pump speed signal612may be provided as a measured motor angle speed in degrees per second to integrator block642, and integrator block642may include one or more calibration parameters configured to convert the measured motor angle speed to a control surface angle speed.

Upon receiving a reset signal, integrator block642may be configured to accumulate and integrate autopilot pump speed signal612to provide an estimated autopilot driven control surface angle to blocks646and652, as shown. In various embodiments, the estimated autopilot driven control surface angle is a measure of the expected autopilot rudder angle accumulated since the reset signal was received (e.g., since the autorelease observation cycle was initiated). If there is no manual user input, the estimated autopilot driven control surface angle should be approximately equal to the actual driven control surface angle (e.g., as derived from rudder reference measurement614).

Rudder reference measurement614(e.g., control surface angle614) may be implemented as a sensor signal from steering sensor/actuator150and be configured to provide precise rudder angle information through direct measurement. In other embodiments, rudder reference measurement614may be implemented as a virtual rudder estimate based, at least in part, on one or more pump control and/or sensor signals, as described herein. In various embodiments, rudder reference measurement614may be provided to blocks640and644.

Upon receiving a reset signal, block640may be configured to store/latch a first rudder reference measurement/actual control surface angle (e.g., corresponding to the initialization of the observation cycle) and provide the stored first rudder reference measurement to block644. Block644may be configured to determine a difference between the first rudder reference measurement and any subsequent rudder reference measurements/actual control surface angles (e.g., after the beginning of the autorelease observation cycle and within the autorelease observation cycle), thereby providing the actual driven control surface angle accumulated since the reset signal was received (e.g., since the autorelease observation cycle was initiated) to block646. Block646may be configured to determine a difference between the actual driven control surface angle provided by block644and the estimated autopilot driven control surface angle provided by block642, and then to provide the resulting estimated manual helm input (e.g., adjusted for proper sign) to comparison block648.

Comparison block648may be configured to selectively enable autopilot release signal/output670based on the estimated manual helm input provided by block646and a predetermined minimum release threshold provided by block617and derived from minimum release threshold616. If the estimated manual helm input is greater than the minimum release threshold provided by block617, comparison block648may be configured to enable autopilot release signal/output670, which also provides a reset signal to OR block628for distribution to blocks617,630,640, and642and, thereby, initialize another autorelease observation cycle. Such reset signal zeros out any estimated manual helm input accumulated during the prior autorelease observation cycle, which allows process600to re-engage the autopilot quickly reliably upon cessation of manual helm input.

Minimum release threshold616may be implemented as a predetermined or preset value stored locally in memory, provided by a user (e.g., through user input provided to user interface120), and/or otherwise made available to controller130and/or block617of process600. Typical values for minimum release threshold616may range between 1 degree and 3 degrees of control surface angle, depending on characteristics of the ship, the steering system, the autopilot, the user, the environmental congestion/navigation hazards, and/or other characteristics. Minimum release threshold616may be a constant, for example, or may be adjusted adaptively based on a state of mobile structure101, such as speed, navigation area, and/or other states of mobile structure101. Block617may be configured to provide a relatively high (e.g., impossibly high) release threshold to blocks648and650to block enablement of the autopilot release signal and/or generation of a reset signal by block652, until process600is properly initialized (e.g., the various inputs are relatively stable and error-free) and a reset signal has been provided to block628by means other than blocks648and/or652. Upon receiving a reset signal, block617may be configured to pass through minimum release threshold616to blocks648and/or650/652, as shown.

In various embodiments, blocks650and652may be configured to keep all autorelease observation cycles relatively short in duration so as to avoid accumulation of errors in process600, and particularly to avoid accumulation of error in the output of integrator block642(e.g., caused by miscalibration and/or insufficient bit depth to properly calibrate an input autopilot pump speed signal612to an output estimated autopilot driven control surface angle). In the embodiment shown inFIG. 6, after an initial reset, minimum release threshold616is provided to gain block650, which may be configured to multiply minimum release threshold616by a value greater than 1 (e.g., an attempt to allow the estimated manual helm input to trigger an autopilot release signal before the estimated autopilot driven control surface angle) and, typically, less than 2 (e.g., to cut off miscalibration errors greater than or equal to twice the minimum release threshold) and provide a resulting maximum integration reliability threshold to block652. In other embodiments, block650may be replaced with another input similar to minimum release threshold616, for example, configured to provide a predetermined maximum integration reliability threshold to block652.

Comparison block652may be configured to compare the estimated autopilot driven control surface angle provided by integrator block642to the maximum integration reliability threshold provided by block650. If the estimated autopilot driven control surface angle is greater than the maximum integration reliability threshold, comparison block652may be configured to provide a reset signal to OR block628for distribution to blocks617,630,640, and642and, thereby, initialize another autorelease observation cycle. Such reset signal prevents motor drive durations from becoming too long (e.g., which risks a calibration error in block642causing false positive triggering/enabling of autopilot release signal/output670).

Output570may in various embodiments be coupled to autopilot pump controller355, for example, and autopilot pump controller355may be configured to discontinue providing pump control signals and/or power to autopilot pump356. In other embodiments, a separate device or switch may be coupled to output570and be configured to electrically decouple autopilot pump controller355and/or autopilot pump356from control signals and/or power. In further embodiments, controller130may be configured to monitor output570and discontinue or pause an autopilot process or system accordingly.

Thus, embodiments of the present disclosure can automatically release an autopilot on a mobile structure without a user having to take the time and distraction to manually activate an autopilot standby button or risk a partially activated autopilot interfering with urgent steering maneuvers. Moreover, various embodiments of the present disclosure may be configured to provide autopilot autorelease with minimal sensor input, including without control surface and/or steering reference sensors, which are typically prone to failure.

Once an autopilot release signal is enabled, even momentarily, the corresponding autopilot (e.g., executed by controller130) may be configured to enter a “release mode” such that autopilot control surface demands are no longer provided to autopilot pump controller355and/or autopilot pump356, thereby allowing a user to control operation of steering sensor/actuator150and/or propulsion system170without constantly fighting the autopilot. While in such release mode, the autopilot may be configured to monitor the appropriate control surface angle (e.g., provided by steering sensor150) and/or a heading of mobile structure101and automatically re-engage the autopilot when manual user input is no longer detected (e.g., rudder angle does not change by more than a threshold amount, such as 1-2 degrees, for a predetermined time period, such as 10-30 seconds).

When the autopilot is re-engaged after being released using the processes described herein, the autopilot may enter one of a variety of modes that may be preselected by a user or a manufacturer. For example, the autopilot may be configured to maintain the new current heading (e.g., continue straight), to maintain the new current heading relative to a measured wind direction, to track to a last valid waypoint and/or track designated prior to the autopilot release signal being enabled, and/or to autopilot mobile structure101according to other operational modes, as described herein.

FIG. 7illustrates a flow diagram corresponding to an embodiment of block617inFIG. 6. When process600ofFIG. 6is initialized, output Q of S-R Flip-Flip710in block617is initialized to zero. Thus, with inputs S and R at zero, output Q remains zero, and switch714selects impossibly high release threshold712for the output748. When the first reset signal arrives at input728, output Q of S-R Flip-Flip710changes to 1 and is locked at 1 until process600reinitializes and output Q is set to zero. Switch714then selects input716(e.g., minimum release threshold616) for output748.

FIG. 8illustrates a flow diagram corresponding to an embodiment of blocks630or640inFIG. 6. In both of blocks630and640, latch input810is coupled to receive a reset signal from block628. When latch input810is zero, switch814selects the output of memory block816, provides that value to output818, and latches/stores that value back into memory block816. When latch input810is 1 (e.g., when the reset signal is received), switch814selects input812and provides that value to memory block816, which then provides that value to output818. When latch input810then reverts to zero, the prior value from input812is latched/stored into memory block816and provided to output818.

FIG. 9illustrates a flow diagram of process400to provide autopilot autorelease in a hydraulic steering system for mobile structure101in accordance with embodiments of the disclosure. In some embodiments, the operations ofFIG. 9may be implemented as software instructions executed by one or more logic devices associated with corresponding electronic devices and/or sensors of system100ofFIG. 1, system200ofFIG. 2, and/or system350ofFIG. 3. More generally, the operations ofFIG. 9may be implemented with any combination of software instructions and/or electronic hardware (e.g., inductors, capacitors, amplifiers, or other analog and/or digital components).

It should be appreciated that any step, sub-step, sub-process, or block of process900may be performed in an order or arrangement different from the embodiments illustrated byFIG. 9. For example, in other embodiments, one or more blocks may be omitted from 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 of systems100,200, and/or350prior to moving to a following portion of a corresponding process. Although process900is described with reference to systems100,200, and350, process900may be performed by other systems different from systems100,200, and350and including a different selection of electronic devices, sensors, mobile structures, and/or mobile structure attributes.

In block902, a logic device receives control surface angles and/or autopilot control surface demands for a mobile structure. For example, controller130may be configured to receive one or more control surface angles (e.g., a measurement of an orientation of rudder266) from steering sensor/actuator150and/or an autopilot control surface demand (e.g., a pump control signal and/or a pump sensor signal corresponding to autopilot pump controller355and/or autopilot pump356) from controller130and/or autopilot pump controller355.

In some embodiments, controller130may be configured to receive various pump control and/or sensor signals, for example, and determine virtual control surface estimates based, at least in part, on the signals. For example, controller130may be implemented and/or operated to determine such virtual control surface estimates (e.g., virtual rudder estimates, in one embodiment) using any one or combination of systems and/or methods described in U.S. patent application Ser. No. 15/222,905 filed Jul. 28, 2016 and entitled “HYDRAULIC SLIP COMPENSATION SYSTEMS AND METHODS”, which is hereby incorporated by reference in its entirety. In such embodiments, controller130may be configured to use the virtual control surface estimates as the control surface angles.

In various embodiments, controller130may also be configured to receive one or more predetermined or preset values associated with process900, such as a predetermined minimum release threshold, for example, or a predetermined maximum integration reliability threshold. In other embodiments, such predetermined or preset values may be stored locally in memory, provided by a user (e.g., through user input provided to user interface120), and/or otherwise made available to controller130.

In block904, a logic device initiates an autorelease observation cycle. For example, controller130may be configured to initiate an autorelease observation cycle based, at least in part, on one or more control surface angles from steering sensor/actuator150and/or an autopilot control surface demand from controller130and/or autopilot pump controller355, such as those received in block902, corresponding to a control surface (e.g., rudder266and/or actuated propulsion system170) for mobile structure101that is actuated by hydraulic steering system350.

In various embodiments, controller130may be configured to determine the control surface demand using any one or combination of systems and/or methods described in U.S. patent application Ser. No. 15/239,760 filed Aug. 17, 2016 and entitled “ACCELERATION CORRECTED ATTITUDE ESTIMATION SYSTEMS AND METHODS”, U.S. Provisional Patent Application No. 62/099,022 filed Dec. 31, 2014 and entitled “STABILIZED DIRECTIONAL CONTROL SYSTEMS AND METHODS”, U.S. Provisional Patent Application No. 62/099,016 filed Dec. 31, 2014 and entitled “ADAPTIVE TRACK KEEPING SYSTEMS AND METHODS”, and/or U.S. Provisional Patent Application No. 62/099,032 filed Dec. 31, 2014 and entitled “PROACTIVE DIRECTIONAL CONTROL SYSTEMS AND METHODS”, which are hereby incorporated by reference in their entirety.

In embodiments where the autopilot control surface demands correspond to pump sensor signals, such as PWM signals, motor speed signals, and/or other power or control signals corresponding to autopilot pump controller355and/or autopilot pump356, for example, controller130may be configured to determine the autopilot control surface rate by determining a value for the pump sensor signals. For instance, a PWM signal may correspond to a positive or negative signal (e.g., a forward or reverse pump motion), and may include an amplitude, pulse width, and/or pulse rate corresponding to an autopilot control surface rate (e.g., where the rate of the pump is roughly directly proportional to the desired rate of change in orientation of the control surface). In another example, autopilot pump speed signal612may correspond to a measure of the motor speed of autopilot pump356and be provided as a function of degrees of control surface angle per second (e.g., derived from a measured tachometer feedback from autopilot pump356, which in turn can be derived from a DC motor back emf, for example).

In embodiments where the autopilot control surface demands correspond to pump control signals (e.g., motor PWM signals610), for example, controller130may be configured to initiate the autorelease observation cycle by detecting an autopilot pump drive reversal based on the pump control signals and initiating the autorelease observation cycle based, at least in part, on the detected autopilot pump drive reversal. For example, blocks622,624, and630of process600may be configured to detect an autopilot pump drive reversal based on motor PWM signal610, and block628may be configured to initiate the autopilot autorelease cycle by issuing a reset signal to blocks630,640,642, and/or617.

In other embodiments, controller130may be configured to initiating the autorelease observation cycle by detecting approximately zero autopilot pump drive for a predetermined minimum period of time, based on the pump control signals, and initiating the autorelease observation cycle based, at least in part, on the detected approximately zero autopilot pump drive for the predetermined minimum period of time. For example, block620of process600may be configured to detect approximately zero autopilot pump drive for a predetermined minimum period of time based on motor PWM signal610, and block628may be configured to initiate the autopilot autorelease cycle by issuing a reset signal to blocks630,640,642, and/or617.

In additional embodiments, controller130may be configured to initiating the autorelease observation cycle upon detecting a prior-enabled autopilot release signal. For example, block648of process600may be configured to enable autopilot release signal670and provide a reset signal to block628, and block628may be configured to initiate the autopilot autorelease cycle by issuing a reset signal to blocks630,640,642, and/or617.

In embodiments where the autopilot control surface demands correspond to autopilot pump speeds provided by an autopilot pump controller of the hydraulic steering system (e.g., autopilot pump speed signals612), for example, controller130may be configured to initiate the autorelease observation cycle by integrating the autopilot pump speed substantially over the duration of the observation cycle to determine an estimated autopilot driven control surface angle, and initiating the autorelease observation cycle upon detecting the estimated autopilot driven control surface angle is greater than a maximum integration reliability threshold. For example, integrator block642may be configured to integrate autopilot pump speed612substantially over a duration of an observation cycle to determine an estimated autopilot driven control surface angle and provide it to block652. Block652may be configured to compare the estimated autopilot driven control surface angle from block642to detect the estimated autopilot driven control surface angle is greater than a maximum integration reliability threshold provided by block650, and then to provide a reset signal to block628, and block628may be configured to initiate the autopilot autorelease cycle by issuing a reset signal to blocks630,640,642, and/or617.

In block406, a logic device selectively enables an autopilot release signal. For example, controller130may be configured to selectively enable an autopilot release signal during the autorelease observation cycle initiated in block904based, at least in part, on the control surface angles and/or the autopilot control surface demands corresponding to the initiated autorelease observation cycle (e.g., those angles, demands, and/or associated signals measured and/or acquired substantially during the initiated autorelease observation cycle).

In embodiments where the control surface angles comprise control surface sensor signals from a control surface sensor of the hydraulic steering system and the autopilot control surface demands comprise pump sensor signals provided by an autopilot pump controller of the hydraulic steering system, for example, controller130may be configured to selectively enable an autopilot release signal by determining an estimated autopilot driven control surface angle corresponding to the autorelease observation cycle based, at least in part, on the pump sensor signals, determining an actual driven control surface angle corresponding to the autorelease observation cycle based, at least in part, on the control surface sensor signals, and selectively enabling the autopilot release signal based, at least in part, on the estimated autopilot driven control surface angle and the actual driven control surface angle.

For example, block642of process600may be configured to determine an estimated autopilot driven control surface angle accumulated during an autorelease observation cycle based on autopilot pump speed signals612, blocks640and644may be configured to determine an actual driven control surface angle accumulated during the autorelease observation cycle based on rudder reference measurements614, and blocks646and648may be configured to selectively enable autopilot release signal670based, at least in part, on the estimated autopilot driven control surface angle from block642and the actual driven control surface angle from block644.

In some embodiments, determining the estimated autopilot driven control surface angle corresponding to the autorelease observation cycle includes integrator block642integrating autopilot pump speed612substantially over the duration of the observation cycle (e.g., from the initialization of the observation cycle as set by the reset signal provided by block628) to determine the estimated autopilot driven control surface angle. In further embodiments, determining the actual driven control surface angle corresponding to the autorelease observation cycle includes determining a difference between first actual control surface angle measured substantially at a beginning of the autorelease observation cycle and a second actual control surface angle measured after the beginning of the autorelease observation cycle and within the autorelease observation cycle (e.g., at block644) to determine the actual driven control surface angle.

In various embodiments, controller130may be configured to selectively enable the autopilot release signal during the autorelease observation cycle by determining an estimated manual helm input (e.g., at block646) based, at least in part, on the control surface angles and/or the autopilot control surface demands corresponding to the initiated autorelease observation cycle (e.g., at blocks640,642,644based on inputs612and614, subject to reset signals provided by block628), determining the estimated manual helm input is greater than a predetermined minimum release threshold (e.g., at block648), and enabling autopilot release signal670.

In some embodiments, controller130may be configured to provide the autopilot release signal to autopilot controller355and/or another device (e.g., a switch) configured to electrically decouple autopilot pump356and/or autopilot pump controller355from power and/or various pump control signals. In some embodiments, controller130may be configured to monitor the autopilot release signal and control itself to discontinue providing pump control signals and/or power to autopilot pump355accordingly.

Notably, none of the methods to determine the state variables described above require a user to actuate a standby mode button or require a user activity sensor at the helm or helm pump to determine when to enable the autopilot release signal. Moreover, none of the methods require a user to actuate a resume button or similar to determine when to disable the autopilot release signal.

Embodiments of the present disclosure can thus disable, decouple, and/or de-energize autopilot pump356of hydraulic steering system350by comparing an intended autopilot rudder rate with a measured rudder rate to disengage the autopilot pump when the helm is sufficiently disturbed by a user/operator. Such embodiments may be used to automatically release the autopilot on a mobile structure without having to manually activate autopilot standby or risking a partially activated autopilot interfering with urgent steering maneuvers.

It is contemplated that any one or combination of methods to provide autopilot release signals may be performed according to one or more operating contexts of a control loop, for example, such as a startup, learning, running, and/or other type operating context. For example, any portion of process900may proceed back to an initial block and proceed through the corresponding process again to retrieve updated control surface angles, autopilot control surface demands, and/or other sensor and/or control signals, as in a control loop. In one embodiment, controller130may be configured to enable the autopilot release signal and then proceed through multiple passes through process900until the various state variables allow controller130to disable the autopilot release signal, as described herein.

FIGS. 10-22illustrate flow diagrams of various control loops and other operations to provide autopilot autorelease in accordance with embodiments of the disclosure. More particularly,FIGS. 10-22illustrate variations on the types of inputs that can be used and the types of processing that can be performed to generate an autopilot release signal for hydraulic steering system350for mobile structure101, as described herein, similar to the flow diagrams, control loops, processes, and blocks described in reference toFIGS. 5-6.

For example, process1000ofFIG. 10accepts inputs1010(e.g., a motor PWM signal and a feedback signal) and provides autopilot release signal output1070. Process1100ofFIG. 11accepts inputs1110(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1170. Process1200ofFIG. 12accepts inputs1210(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1270. Process1300ofFIG. 13accepts inputs1310(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1370. Process1400ofFIG. 14accepts inputs1410(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1470. Process1500ofFIG. 15accepts inputs1510(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1570.

Process1600ofFIG. 16accepts inputs1610(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1670. Process1700ofFIG. 17accepts inputs1710(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1770. Process1800ofFIG. 18accepts inputs1810(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1870. Process1900ofFIG. 19accepts inputs1910(e.g., an autopilot pump speed signal and a rudder reference measurement) and provides autopilot release signal output1970.

Process2000ofFIG. 20Aaccepts inputs2010(e.g., an autopilot pump speed signal, a rudder reference measurement, and a sensitivity setting) and provides autopilot release signal output2070. In some embodiments, process2000may also be configured to provide a required steering rate output as feedback from process2000. Block2020of process2000is detailed inFIG. 20Band accepts inputs2022(e.g., an angle input and a motor input, which may be a motor PWM signal or an autopilot pump speed signal, for example) and provides output2022(e.g., a sustained drive signal).

Process2100ofFIG. 21accepts inputs2110(e.g., a motor PWM signal, an autopilot pump speed signal, a rudder reference measurement, and a minimum release threshold) and provides autopilot release signal output2170. Process2200ofFIG. 22accepts inputs2210(e.g., a motor PWM signal, an autopilot pump speed signal, a rudder reference measurement, and a minimum release threshold) and provides autopilot release signal output2270.