ADAPTIVE AUTOPILOT CONTROL SYSTEMS AND METHODS

• US 20170277189A1
• Filed: 06/12/2017
• Published: 09/28/2017
• Est. Priority Date: 01/31/2013
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Johnson, Mark, Matt, Ian, Yeomans, Christopher, Sabaliaushas, Gytis, Pope, Gordon
• Granted Patent: US 10,747,226 B2
• Time in Patent Office: Days
• CPC Class Codes: B63B 2035/009 Wind propelled vessels comprising arrangements, installations or devices specially adapted therefor, other than wind propulsion arrangements, installations, or devices, such as sails, running rigging, or the like, and other than sailboards or the like or related equipment
• CPC Class Codes: B63H 2025/045 making use of satellite radio beacon positioning systems, e.g. the Global Positioning System [GPS]
• CPC Class Codes: B63H 25/04 automatic, e.g. reacting to compass
• CPC Class Codes: B63H 25/06 Steering by rudders by rudders carrying propellers B63H25/42
• CPC Class Codes: G01S 15/86 Combinations of sonar systems with lidar systems; Combinations of sonar systems with systems not using wave reflection
• CPC Class Codes: G01S 15/89 for mapping or imaging
• CPC Class Codes: G01S 15/96 for locating fish
• CPC Class Codes: G01S 19/42 Determining position
• CPC Class Codes: G05D 1/0206 specially adapted to water vehicles

Abstract

Autopilot systems and related techniques are provided to improve the ability of mobile structures to maintain a desired reference path (e.g., to keep a desired track and/or to follow a desired contour). In various embodiments, a high quality turn rate signal and GPS based signals are used to generate high bandwidth cross track/contour errors and other associated signals. An adaptive controller uses the generated cross track/contour signals to provide robust track keeping and/or contour following in the directional control of a mobile structure. Techniques are also provided for systems and methods to provide directional control for mobile structures.

Claims

1. A system comprising:

a logic device configured to receive one or more sensor signals and generate one or more control signals to provide directional control for a mobile structure along a reference path, wherein the logic device is configured to perform a method comprising;

receiving a yaw rate, position, and/or velocity of the mobile structure;

determining a cross track error relative to the reference path for the mobile structure based, at least in part, on the yaw rate, position, and/or velocity; and

determining a steering demand for the mobile structure based, at least in part, on the cross track error.

2. The system of claim 1, wherein the determining the cross track error comprises:

determining a cross track acceleration for the mobile structure based, at least in part, on the yaw rate;

integrating the cross track acceleration to determine a cross track velocity for the mobile structure; and

/or

integrating the cross track velocity to determine the cross track error for the mobile structure.

3. The system of claim 2, wherein the determining the steering demand comprises multiplying the cross track acceleration, cross track velocity, and/or cross track error by one or more associated gains.

4. The system of claim 2, wherein the integrating the cross track acceleration is referenced to a position-based cross track velocity derived, at least in part, from measured positions of the mobile structure.

5. The system of claim 1, wherein the method performed by the logic device further comprises:

determining a bearing associated with the reference path; and

determining a cross track velocity reference using the bearing, wherein the cross track error is based, at least in part, on the cross track velocity reference.

6. The system of claim 1, further comprising the mobile structure, wherein:

the mobile structure is a watercraft comprising a steering actuator and a rudder; and

the steering actuator is configured to receive the steering demand and actuate the rudder to maintain the watercraft substantially along the reference path.

7. The system of claim 1, wherein the method performed by the logic device further comprises limiting the steering demand according to a maximum acquisition angle associated with the mobile structure, wherein the limiting is performed in response to a user selected responsiveness setting.

8. The system of claim 1, further comprising a user interface configured to display the steering demand and/or an angle associated with the steering demand to a user.

9. The system of claim 1, wherein the reference path is a specified track between at least two waypoints.

10. The system of claim 1, wherein the reference path is a specified contour associated with a sea bed depth, wherein the cross track error is an effective cross track error based on a depth error divided by a cross slope associated with the specified contour.

11. The system of claim 10, wherein:

the system further comprises a sonar system;

the method performed by the logic device further comprises;

controlling the sonar system to determine the depth and the cross slope;

determining the depth error by subtracting a target depth of the specified contour from the depth; and

determining the effective cross track error by dividing the depth error by the cross slope.

12. The system of claim 1, wherein the method performed by the logic device further comprises:

receiving a steering angle and a steering rate of the mobile structure, wherein the steering angle is based, at least in part, on the steering demand;

determining a nominal steering angle based, at least in part, on the steering rate;

determining a nominal feedback signal based, at least in part, on a combination of the steering angle and the nominal steering angle; and

adjusting the steering demand by the nominal feedback signal.

13. The system of claim 12, wherein the determining the nominal feedback signal comprises determining a difference between the nominal steering angle and the steering angle.

14. The system of claim 12, wherein the determining the nominal steering rate comprises:

processing the steering rate with a nominal predictor;

receiving the nominal steering angle from the nominal predictor, wherein the nominal predictor comprises a transfer function configured to model dynamics of a nominal mobile structure derived, at least in part, from a selection of mobile structures; and

wherein the transfer function comprises a ratio of a nominal steering rate lag term to a nominal steering rate gain term.

15. The system of claim 14, wherein:

the transfer function comprises a ratio of a nominal steering rate lag term to a nominal steering rate gain term;

the nominal steering rate lag is set to zero within the nominal predictor; and

the determining the nominal feedback signal comprises determining a delayed steering angle based, at least in part, on the steering angle, and determining a difference between the nominal steering angle and the delayed steering angle.

16. The system of claim 12, wherein the method performed by the logic device further comprises:

limiting the steering demand to produce a steering actuator rate demand less than a steering actuator rate limit and/or a steering demand less than a steering actuator angle limit;

receiving a user-selectable responsiveness setting; and

modifying, based on the responsiveness setting, one or more gains, a deadband, and/or a limit used to determine the steering demand.

17. The system of claim 12, wherein the method performed by the logic device further comprises:

adjusting the steering demand by the nominal feedback signal; and

providing the adjusted nominal feedback signal to a steering actuator.

18. The system of claim 12, wherein the method performed by the logic device further comprises:

providing the nominal feedback signal to a single-band or multi-band bandwidth-selectable filter to produce a filtered nominal feedback signal;

adjusting the steering demand using the filtered nominal feedback signal; and

modifying at least one bandwidth of the bandwidth-selectable filter based on a user-selectable responsiveness setting.

19. The system of claim 12, wherein:

the steering rate comprises a yaw rate of the mobile structure;

the yaw rate comprises a compensated yaw rate of the mobile structure; and

the compensated yaw rate is determined after a pitch, pitch rate, roll, and/or roll rate of the mobile structure are determined to reduce a pitch-induced noise in the compensated yaw rate.

20. The system of claim 12, wherein the mobile structure is a watercraft comprising:

a rudder;

a steering actuator configured to receive the steering demand provided as one of the control signals and configured to actuate the rudder;

a steering sensor fixed relative to the watercraft and configured to provide the steering angle as at least a first one of the sensor signals; and

a steering rate sensor fixed relative to the watercraft and configured to provide the steering rate as at least a second one of the sensor signals.