Systems and Methods for Controlling Steering of a Marine Drive

The present disclosure generally relates to methods and systems for propelling marine vessels, and more particularly to systems and methods for controlling steering of marine drives that are steerable to a range of steering positions.

Many different types of marine drives are well known to those skilled in the art. For example, steerable marine drives may be mounted to or in the rear of the vessel, such as outboard motors that are attached to the transom of a marine vessel and stern drive systems that extend in a rearward direction from the stern of a marine vessel. Marine drives generally comprise a powerhead, such as an electric motor or an internal combustion engine, driving rotation of a drive shaft that is directly or indirectly connected to a propeller on a propeller shaft and that imparts rotation thereto. Some marine propulsion systems include groups of two or more and separately steerable marine drives at the rear of the marine vessel to enable surge, sway, and yaw directional control. The steerable marine drives are each steerable about their steering axis to a range of steering angles, which is effectuated by a remotely controlled steering actuator, often referred to as a steer-by-wire system.

The following U.S. patents, publications, and applications are incorporated herein by reference, in entirety:

U.S. Pat. No. 6,322,404 discloses a Hall Effect rotational position sensor mounted on a pivotable member of a marine propulsion system. A rotatable portion of the rotational position sensor is attached to a drive structure of the marine propulsion system. Relative movement between the pivotable member, such as a gimbal ring, and the drive structure, such as the outboard drive portion of the marine propulsion system, cause relative movement between the rotatable and stationary portions of the rotational position sensor. As a result, signals can be provided which are representative of the angular position between the drive structure and the pivotable member.

U.S. Pat. No. 7,467,595 discloses a method for controlling the movement of a marine vessel that rotates one of a pair of marine drives and controls the thrust magnitudes of two marine drives. A joystick is provided to allow the operator of the marine vessel to select port-starboard, forward-reverse, and rotational direction commands that are interpreted by a controller which then changes the angular position of at least one of a pair of marine drives relative to its steering axis.

U.S. Pat. No. 10,450,043 discloses a trolling motor system for a watercraft includes a trolling motor assembly coupled to the watercraft. A foot pedal is mechanically coupled to the trolling motor assembly such that mechanical inputs to the foot pedal cause movement of a moveable component of the trolling motor assembly. A steering motor is configured to steer the trolling motor assembly. The movement of the moveable component of the trolling motor assembly generates electrical inputs to the steering motor, thereby activating the steering motor to steer the trolling motor assembly.

U.S. Pat. No. 11,372,411 discloses a steering system on a marine vessel that includes at least one propulsion device, a steering actuator that rotates the propulsion device to effectuate steering, at least one trim device moveable to adjust a running angle of the vessel, and a trim actuator configured to move the trim device so as to adjust the running angle. The system further includes a control system configured to determine a desired roll angle and at least one of a desired turn rate and a desired turn angle for the marine vessel based on a steering instructions. The control system then controls the steering actuator to the rotate the at least one propulsion device based on the desired turn rate and/or the desired turn angle, and to control the trim actuator to move the at least one trim device based on the desired roll angle so as to effectuate the steering instruction.

This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

According to one aspect, a steering system for a marine drive includes a marine drive, wherein the marine drive is steerable about a steering axis, a steering actuator configured to steer the marine drive to a range of steering positions within a permitted steering range, a first steering sensor configured to sense the steering position of the marine drive and output a first sensed value, a second steering sensor configured to sense the steering position of the marine drive and output a second sensed value and a controller. The controller is configured to calculate a measured steering position for the marine drive based on the first sensed value and the second sensed value and control the steering actuator based on the measured steering position.

In one embodiment, the measured steering position is calculated as an average of the first sensed value and the second sensed value.

In another embodiment, the measured steering position is a value between the first sensed value and the second sensed value.

In another embodiment, the measured steering position is calculated as a filtered output of the first sensed value and the second sensed value.

In another embodiment, the controller is further configured to detect a fault condition if a difference between the first sensed value and the second sensed value exceeds a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to the fault condition.

In another embodiment, wherein the controller is further configured to, in response to detecting a fault condition of the first steering sensor or the second steering sensor, redetermine the measured steering position based on only the first sensed value or the second sensed value and adjust the steering position of the marine drive based on the redetermined measured steering position.

In another embodiment, the controller is configured such that a difference between the first sensed value and the second sensed value does not exceed a difference threshold, wherein the difference threshold is configured such that the steering position of the marine drive is not adjusted by more than a predetermined maximum tolerated uncommanded steering change in response to the fault condition.

In another embodiment, the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to a fault condition.

In another embodiment, the difference threshold is two times the predetermined maximum tolerated uncommanded steering change.

In another embodiment, the predetermined maximum tolerated uncommanded steering change is a 3-degree change in steering angle.

In another embodiment, the controller is further configured to determine a difference between the first sensed value and the second sensed value, compare the difference to a difference threshold, and detect a fault condition if the difference exceeds the difference threshold.

In another embodiment, the controller is further configured to disable the steering actuator in response to the detection of the fault condition.

In another embodiment, in response to the detection of the fault condition, redetermine the measured steering position based on only one of the first steering sensor or the second steering sensor, operate the steering actuator to automatically change the steering position of the marine drive based on the redetermined measured steering position, wherein the difference threshold is associated with a predetermined maximum tolerated uncommanded steering change in response to the detection of the fault condition.

In another embodiment, each of the first steering sensor and the second steering sensor is a Hall Effect sensor.

According to another aspect, a method of controlling steering of a marine drive configured to propel a marine vessel includes sensing the steering position of the marine drive with a first steering sensor to output a first sensed value, sensing the steering position of the marine drive with a second steering sensor to output a second sensed value, calculating a measured steering position for the marine drive based on the first sensed value and the second sensed value, and steering the marine drive based on the measured steering position.

In one embodiment, the measured steering position is calculated as an average of the first sensed value and the second sensed value.

In another embodiment, the measured steering position is a value between the first sensed value and the second sensed value.

In another embodiment, the measured steering position is calculated as a filtered output of the first sensed value and the second sensed value.

In another embodiment, wherein the method further includes detecting a fault condition if a difference between the first sensed value and the second sensed value exceeds a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to the fault condition.

In another embodiment, the method further includes, in response to detecting a fault condition of the first steering sensor or the second steering sensor, redetermining the measured steering position based on only the first sensed value or the second sensed value, and adjusting the steering position of the marine drive based on the redetermined measured steering position.

In another embodiment, the method further includes continuing to control steering of the marine drive based on the measured steering position provided that a difference between the first sensed value and the second sensed value does not exceed a difference threshold, wherein the difference threshold is configured such that the steering position of the marine drive is not adjusted by more than a predetermined maximum tolerated uncommanded steering change in response to the fault condition.

In another embodiment, the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to a fault condition.

In another embodiment, the difference threshold is two times the predetermined maximum tolerated uncommanded steering change.

In another embodiment, the predetermined maximum tolerated uncommanded steering change is a 3-degree change in steering angle.

According to another aspect of the present disclosure, a method of controlling rotation of a rotatable device for controlling roll, pitch, and/or yaw of a marine vessel includes sensing a position of the rotatable device with a first sensor to output a first sensed value, sensing the position of the rotatable device with a second sensor to output a second sensed value, calculating a measured position for the rotatable device on the first sensed value and the second sensed value, and controlling movement of the rotatable device based on the measured position.

In one embodiment, the rotatable device is a steerable marine drive.

In another embodiment, the rotatable device is a steerable rudder.

In another embodiment, the rotatable device is a trim tab.

In another embodiment, the rotatable device is a trimmable marine drive rotatable about a trim axis by a trim actuator.

Various other features, objects, and advantages of the invention will be made apparent from the following description taken together with the drawings.

The inventor has recognized a need for vessel control systems and methods that provide improved control over steering of the marine vessel when the quality of the steering sensor(s) is poor or when a steering sensor fails. Some steering systems include a primary sensor and a backup sensor so that when a sensor failure occurs and the controller switches from the failed steering sensor to second, backup, steering sensor to control steering. However, switching from the primary sensor to the backup sensor causes a step change in steering position to be effectuated based on a difference between the last valid steering position value outputted by the failed sensor and the steering position value outputted by the backup steering sensor. In some embodiments, the step change when switching between steering sensors can approach an intolerable magnitude, and thus systems may be configured to generate a steering fault when the difference between outputs of the main steering sensor and the backup steering sensor diverge by more than a threshold amount.

The inventor has endeavored to develop a steering system that utilizes two steering position sensors, where the output of both sensors is utilized for steering control and fault diagnostic purposes unless one of the sensors is faulted. For example, both the first and second sensors may be Hall Effect sensors, potentiometers, or some other sensor type, and in some embodiments the first and second sensors may be different sensor types. The disclosed system and method includes two steering sensors configured to sense the steering position of a single steered element, such as a steerable marine drive, and is configured to calculate a measured steering position for the steerable element based on a first sensed value outputted by a first steering sensor and a second sensed value outputted by a second steering sensor. The measured steering position is then used as a feedback value for controlling steering, where the steering actuator is controlled based on a comparison between a commanded steering position and the measured steering position that is calculated based on the output of the two steering sensors. For example, the measured steering position output may be calculated as an average of the first and second sensed values. In other embodiments, the measured steering position may be determined as a value between the first and second sensed values, which may be calculated or otherwise generated in various ways, such as the output of a filter receiving both sensed inputs.

The method of combining both sensors improves fault tolerance and resilience of the system while avoiding an increase in steering change magnitude when one of the sensors fails. In response to detecting a fault condition in one of the two steering sensors, the controller redetermines the measured steering position of the marine drive based on only the output of the remaining steering sensor and adjusts the steering position of the marine drive based on the redetermined measured steering position. Since the measured steering position is a value between the first and second sensed positions, the step change in sensed steering position will be less than the step change that would be induced by switching from reliance on only one sensor to reliance on only the other steering sensor. For example, if the measured steering position is an average of the first and second sensed positions, then the step change will be half of that caused by switching from one sensor to the other. Therefore, the inventive system and method have the benefit of increasing the fault tolerance of the system by decreasing the step change in sensed steering position when one of the two sensors experiences a fault—and thus reducing the uncommanded steering change effectuated in response to the fault condition.

In one embodiment, the controller is further configured to detect a fault condition if a difference between the first sensed value and the second sensed value exceeds a difference threshold, wherein the difference threshold is based on a predetermined maximum tolerated uncommanded steering change effectuated in response to the fault condition. In embodiments, where both sensors have a fault and are unusable, the controller may preserve limited navigational capacity wherein steering adjustment is manual.

Similarly, the disclosed dual sensor system may be incorporated in other types of control systems for controlling rotatable devices to control vessel roll, pitch, and/or yaw. The disclosed method and control system for controlling roll, pitch, and/or yaw of a marine vessel includes sensing a position of the rotatable device with a first sensor to output a first sensed value, sensing the position of the rotatable device with a second sensor to output a second sensed value, calculating a measured position for the rotatable device on the first sensed value and the second sensed value, and controlling movement of the rotatable device based on the measured position. The rotatable device may be a steerable drive, such as an outboard drive, a stern drive, a tolling motor, or the like. In other implementations, the rotatable device may be a steerable rudder, or other steerable device, or may be a trimmable device such as a trim tab, a trim plate, or a trimmable drive. Although the invention is illustrated herein with respect to steering position sensors associated with a steerable marine drive, the inventive system and method with dual position sensors may be applied to sensing and controlling the position of any of the forgoing marine steering and/or trim devices.

are schematic representations of a propulsion systemfor a marine vessel. The embodiment shown inincludes one rear marine drivepositioned at the stern, such as attached to the transom of the vessel. The single rear marine drivemay be mounted along a centerline CL of vessel. The single rear marine drivemay be, for example, an outboard drive, a stern drive, a pod drive, a jet drive, or any other type of steerable drive. The rear marine driveis steerable to a range of steering angles within a permitted steering range, having a steering actuatorconfigured to rotate the driveabout its vertical steering axis. The steering axisis positioned at a distance X from the center of turn (COT), which could also be the effective center of gravity (COG). A first steering sensorand a second steering sensorare configured to sense the steering position of the marine drive and each output a sensed value. The first steering sensoroutputs a first sensed value and the second steering sensoroutputs a second sensed value. The sensed values are communicatively connected to a controller that calculates a measured steering position for the marine drive based on the first and second sensed values and controls the steering actuatorto rotate the marine drivebased on the measured steering position. Rotating the rear marine driveand effectuating thrust thereby causes rotation of the marine vesselabout the effective COT.

The marine vesselis maneuvered, such as according to a user-inputted steering command, by causing the marine drive to rotate about its steering axis. The marine driveis rotated in response to an operator's manipulation of the steering wheelor joystick, wherein the rotational position of the marine driveis sensed by the first and second steering sensorsand. The propulsion systemmay include one or more alternative or additional user input device(s), such as a joystick or a keypad, operable by a user to provide steering input, such as a lateral movement demand input and/or rotational movement demand input.

The user steering inputs provided at the user input deviceand/or the steering wheelare received by the control system, which may include multiple control devices communicatively connected via a communication link, such as a CAN bus (e.g., a CAN Kingdom Network), to control the propulsion systemas described herein. In the embodiment of, the control systemincludes a central controllercommunicatively connected to the drive control module (DCM),of each marine drive,and may also include other control devices. Thereby, the controllercan communicate instructions to the DCM,of each drive,, or may otherwise communicate directly to each steering actuator(s)to effectuate a steering action based on user input at the steering input device,. At least two steering sensorsand,andare configured to sense the steering angle, or steering position, of each drive,. The control system, such as by the central controlleror each DCM,, is configured to determine the measured steering position for each drive,based on the outputs of the two or more steering sensors associated with that drive, as is disclosed herein. The steering actuatorsare then controlled accordingly, such as based on a comparison of the commanded steering position and the measured steering position.

In one embodiment, the central controlleralso communicates a command instruction to the DCM,for the marine drive, which includes a steering position instruction, and wherein the commands to the various drives,are coordinated such that the total of the thrusts yields the user's propulsion demand input. A person of ordinary skill in the art will understand in view of the present disclosure that other control arrangements could be implemented and are within the scope of the present disclosure, and that the control functions described herein may be combined into a single controller or divided into any number of a plurality of distributed controllers that are communicatively connected.

Also referencing, a schematic representation of a propulsion systemis shown including two marine drivesandconfigured to be positioned at the stern, such as attached to the transom. Each marine drive,, whether in a single drive arrangement or an arrangement of two or more rear drives, includes a powerhead,configured to rotate a propellerin each of a forward rotational direction to effectuate a forward thrust on the vesseltending to move it in the forward direction and a reverse rotational direction to effectuate a reverse thrust on the vesseltending to move it backward. The powerhead,may comprise, for example, an electric motor, an internal combustion engine, or a hybrid arrangement of an electric motor or motor/generator and an internal combustion engine. The number of marine drives is exemplary and a person having ordinary skill in the art will understand in light of the present disclosure that any number of one or more marine drives steerable to a range of steering angles may be utilized in the disclosed system and method. A rotational speed sensor,is associated with each powerhead,and configured to sense a rotational speed thereof. A person having ordinary skill in the art will understand in view of the present disclosure that the disclosed propulsion systemmay include other types and locations of marine drives, which may be an alternative to or in addition to the one or more rear marine drives,. Where one or more of the marine drives,is an electric drive—i.e., having a powerhead being an electric motor-the propulsion systemwill include a power storage device (e.g., battery) powering the motor(s) thereof.

Each marine drive,is individually and separately steerable, each having a respective steering actuatorconfigured to rotate the drive,about its respective steering axis, as is standard. In some examples, the entire drive is a steerable drive (such as with certain outboard drive arrangements) and in some examples, the portion of the drive containing the propeller steers independent of the powerhead (such as with certain stern drive arrangements or steerable gearcase arrangements). The steering axesare separated by a dimension along the Y axis and at a distance X from the center of turn(COT), which could also be the effective center of gravity (COG). The marine vesselis maneuvered by causing the first and second marine drives to rotate about their respective steering axis. The marine drivesandare rotated in response to an operator's manipulation of the joystickor steering wheel, which are each communicatively connected to the steering actuatorsthat rotate the marine drivesand. Rotating the rear marine drivesandand effectuating thrusts thereby causes turn of the marine vessel, which may include turn about the effective COT(which may alternatively be the center of pressure (COP) or center of gravity (COG)).

Each rear marine drive,is steerable to a range of steering angles, such as 30 degrees from a centered steering position or about 45 degrees from a centered steering position each of a clockwise rotation and counterclockwise rotation direction. In some embodiments, one or more of the marine drives may be steerable to enable rotation of the propeller to 90 degrees or more of steering in at least one direction from a centered steering position (e.g., parallel to the centerline CL).