Systems and methods for orienting a marine vessel to minimize pitch or roll
Systems and methods for orienting a marine vessel minimize at least one of pitch and roll in a station keeping mode. A control device having a memory and a programmable circuit is programmed to control operation of the plurality of marine propulsion devices to maintain orientation of a marine vessel in a selected global position and heading. The control device receives at least one of actual pitch and actual roll of the marine vessel in the global position and controls operation of the plurality of marine propulsion units to change the heading of the marine vessel to minimize at least one of the actual pitch and the actual roll while maintaining the marine vessel in the selected global position.
1. A system for orienting a marine vessel, comprising:
a plurality of marine propulsion devices configured to orient a marine vessel;
a control device having a memory and a programmable circuit, the control device configured to control operation of the plurality of marine propulsion devices to maintain orientation of the marine vessel in a selected global position and heading;
wherein the control device is configured to receive pitch and roll of the marine vessel in the global position;
wherein the control device is configured to control operation of the plurality of marine propulsion units to change the heading of the marine vessel to minimize one of the pitch and the roll while maintaining the marine vessel in the selected global position; and
a user input device configured to allow a user to select between at least two different modes of control device operation, including a Pitch Minimization Mode wherein the control device controls operation of the plurality of marine propulsion units to minimize the pitch and a Roll Minimization Mode wherein the control device controls operation of the plurality of marine propulsion units to minimize the roll.
2. A system according to claim 1 , comprising an inertial measurement unit measuring and providing the at least one of the pitch and the roll to the control device.
3. A system according to claim 2 , wherein the user input device comprises a joystick.
4. A system according to claim 1 , wherein the marine vessel extends along a longitudinal axis from a bow to a stern and wherein the marine vessel extends along a lateral axis from a ports side to a starboard side, the longitudinal axis being perpendicular to the lateral axis, and wherein the control device is configured to control operation of the plurality of marine propulsion units to reduce the roll by creating an effective moment arm on the marine vessel that causes the marine vessel to rotate until the longitudinal axis is aligned with a direction in which an external wave force is acting on the marine vessel.
5. A system according to claim 1 , wherein the marine vessel extends along a longitudinal axis from a bow to a stern and wherein the marine vessel extends along a lateral axis from a ports side to a starboard side, the longitudinal axis being perpendicular to the lateral axis, and wherein the control device is configured to control operation of the plurality of marine propulsion units to reduce the pitch by creating an effective moment arm on the marine vessel that causes the marine vessel to rotate until the lateral axis is aligned with a direction in which an external wave force is acting on the marine vessel.
6. A system according to claim 1 , wherein the control device is configured to minimize the pitch and the roll by performing a gradient search method.
7. A system according to claim 6 , wherein the gradient search method comprises:
a. measuring a first peak pitch;
b. changing the heading of the marine vessel by a predetermined positive amount;
c. measuring a second peak pitch; and
d. repeating steps (a) through (c) if the first peak pitch is greater than the second peak pitch.
8. A system according to claim 7 , wherein the gradient search method comprises:
e. changing the heading of the marine vessel by a predetermined negative amount if the first peak pitch is less than the second peak pitch.
9. A system according to claim 6 , wherein the gradient search method comprises:
a. measuring a first peak roll;
b. changing the heading of the marine vessel by a predetermined positive amount;
c. measuring a second peak roll; and
d. repeating steps (a) through (c) if the first peak roll is greater than the second peak roll.
10. A system according to claim 9 , wherein the gradient search method comprises:
e. changing the heading of the marine vessel by a predetermined negative amount if the first peak roll is less than the second peak roll.
11. A system according to claim 1 , wherein the control device is programmed to actively control operation of the plurality of marine propulsion units to continuously minimize the one of the pitch and the roll.
12. A system according to claim 1 , wherein the control device is programmed to control operation of the plurality of marine propulsion units to create a moment arm that causes rotation of the marine vessel about its center of gravity to minimize the at least one of the pitch and the roll.
13. A method for orienting a marine vessel, comprising:
operating a control system for maintaining a global position and heading of the marine vessel;
determining pitch and roll of the marine vessel in the global position;
operating the control system to change the heading of the marine vessel to minimize one of the pitch and the roll while maintaining the marine vessel in the global position; and
selecting between at least two different modes of control system operation including a Pitch Minimization Mode wherein the control system controls operation of the plurality of marine propulsion units to minimize pitch and a Roll Minimization Mode wherein the control system controls operation of the plurality of marine propulsion units to minimize roll.
14. A method according to claim 13 , wherein the marine vessel extends along a longitudinal axis from a bow to a stern and wherein the marine vessel extends along a lateral axis from a port side to a starboard side, the longitudinal axis being perpendicular to the lateral axis, and comprising operating the control system to reduce roll by creating an effective moment arm on the marine vessel that causes the marine vessel to rotate until the longitudinal axis is aligned with a direction in which an external wave force is acting on the marine vessel.
15. A method according to claim 13 , wherein the marine vessel extends along a longitudinal axis from a bow to a stern and wherein the marine vessel extends along a lateral axis from a ports side to a starboard side, the longitudinal axis being perpendicular to the lateral axis, and comprising operating the control system to reduce pitch by creating an effective moment arm on the marine vessel that causes the marine vessel to rotate until the lateral axis is aligned with a direction in which an external wave force is acting on the marine vessel.
16. A method according to claim 13 , comprising minimizing one of the pitch and the roll by performing a gradient search method.
17. A method according to claim 12 wherein the gradient search method comprises:
a. measuring a first peak pitch;
b. changing the heading of the marine vessel by a predetermined positive amount;
c. measuring a second peak pitch; and
d. repeating steps (a) through (c) if the first peak pitch is greater than the second peak pitch.
18. A method according to claim 17 wherein the gradient search method further comprises:
e. changing the heading of the marine vessel by a predetermined negative amount if the first peak pitch is less than the second peak pitch.
19. A method according to claim 18 wherein the gradient search method comprises:
a. measuring a first peak roll;
b. changing the heading of the marine vessel by a predetermined positive amount;
c. measuring a second peak roll; and
d. repeating steps (a) through (c) if the first peak roll is greater than the second peak roll.
20. A method according to claim 19 wherein the gradient search method further comprises:
e. changing the heading of the marine vessel by a predetermined negative amount if the first peak roll is less than the second peak roll.
21. A method according to claim 13 comprising operating the control system to change the heading of the marine vessel by controlling operation of the plurality of marine propulsion devices to create a moment arm that causes rotation of the marine vessel about a center of gravity of the marine vessel.