Marine vessel station keeping to reduce wear and noise on propulsion system
A method for maintaining a marine vessel at a target position in a body of water, the method being carried out by a processing system and including: estimating at least one roughness condition of the body of water based on measurements related to an attitude of the marine vessel; calculating a desired linear velocity based on a difference between an actual position of the marine vessel and the target position; filtering an actual linear velocity of the marine vessel based on the roughness conditions; and operating a propulsion system of the marine vessel to move the marine vessel to minimize a difference between the desired linear velocity and the filtered actual linear velocity. A method for maintaining a marine vessel at a target heading in a body of water is also disclosed.
1. A method for maintaining a marine vessel at a target position in a body of water while reducing wear and noise of a propulsion system, the method being carried out by a processing system operably coupled to a propulsion system and comprising:
estimating, by the processing system, at least one roughness condition of the body of water based on measurements related to an attitude of the marine vessel, wherein the estimated at least one roughness condition represents water roughness conditions that cause repeated pitch and roll on the vessel about the target position;
calculating, by the processing system, a desired linear velocity based on a difference between an actual position of the marine vessel and the target position;
filtering, by the processing system, an actual linear velocity of the marine vessel based on the at least one roughness condition to facilitate a reduction in wear and noise of the propulsion system; and
operating, by the processing system, the propulsion system of the marine vessel to move the marine vessel to minimize a difference between the desired linear velocity and the filtered actual linear velocity, wherein operating the propulsion system based on the filtered actual linear velocity reduces wear and noise of the propulsion system, relative to operating the propulsion system based on the actual linear velocity, by reducing effects that recurring errors caused by rough water conditions corresponding to the actual linear velocity have on a frequency of corrective control actions performed by the propulsion system.
2. The method of claim 1 , wherein the attitude of the marine vessel includes vessel pitch measurements and/or vessel roll measurements from one or more pitch sensors and/or one or more roll sensors.
3. The method of claim 2 , wherein estimating the at least one roughness condition comprises calculating a variance of the pitch measurements and/or a variance of the roll measurements.
4. The method of claim 3 , further comprising storing the pitch measurements and/or the roll measurements in respective circular buffers in a storage system communicatively coupled with the processing system.
5. The method of claim 3 , further comprising filtering a fore/aft component of the position difference based on the variance of the pitch measurements;
filtering a left/right component of the position difference based on the variance of the roll measurements; and
calculating the desired linear velocity based on the filtered fore/aft component of the position difference and the filtered left/right component of the position difference.
6. The method of claim 3 , further comprising filtering a fore/aft component of the actual linear velocity based on the variance of the pitch measurements; and
filtering a left/right component of the actual linear velocity based on the variance of the roll measurements.
7. The method of claim 1 , further comprising setting the desired linear velocity to zero in response to the position difference being inside a predefined position difference hysteresis band.
8. The method of claim 7 , further comprising determining the position difference hysteresis band based on the at least one roughness condition.
9. The method of claim 1 , wherein operating the propulsion system to move the marine vessel to minimize the difference between the desired linear velocity and the filtered actual linear velocity comprises calculating marine vessel movements that will minimize the difference between the desired linear velocity and the filtered actual linear velocity using a feedback control algorithm;
the method further comprising determining a gain for use in the feedback control algorithm based on the at least one roughness condition.
10. The method of claim 1 , further comprising:
calculating a desired rotational velocity based on a difference between an actual heading of the marine vessel and a target heading at which the marine vessel is to be maintained;
filtering an actual rotational velocity of the marine vessel based on the at least one roughness condition; and
operating the propulsion system to move the marine vessel to minimize both the difference between the desired linear velocity and the filtered actual linear velocity and a difference between the desired rotational velocity and the filtered actual rotational velocity.
11. A method for maintaining a marine vessel at a target heading in a body of water while reducing wear and noise of a propulsion system, the method being carried out by a processing system operably coupled to the propulsion system and comprising:
estimating, by the processing system, at least one roughness condition of the body of water based on measurements related to an attitude of the marine vessel wherein the estimated at least one roughness condition represents water roughness conditions that cause repeated pitch and roll on the vessel about the target heading;
calculating, by the processing system, a desired rotational velocity based on a difference between an actual heading of the marine vessel and the target heading;
filtering, by the processing system, an actual rotational velocity of the marine vessel based on the at least one roughness condition to facilitate a reduction in wear and noise of the propulsion system; and
operating, by the processing system, the propulsion system of the marine vessel to move the marine vessel to minimize a difference between the desired rotational velocity and the filtered actual rotational velocity, wherein operating the propulsion system based on the filtered actual rotational velocity reduces wear and noise of the propulsion system, relative to operating the propulsion system based on the actual rotational velocity, by reducing effects that recurring errors caused by rough water conditions corresponding to the actual rotational velocity have on a frequency of corrective control actions performed by the propulsion system.
12. The method of claim 11 , wherein the attitude of the marine vessel includes pitch measurements and/or vessel roll measurements from one or more pitch sensors and/or one or more roll sensors.
13. The method of claim 12 , wherein estimating the at least one roughness condition comprises calculating a variance of the pitch measurements and/or the roll measurements.
14. The method of claim 13 , further comprising storing the pitch measurements and/or the roll measurements in a circular buffer in a storage system communicatively coupled to the processing system.
15. The method of claim 11 , further comprising filtering the difference between the actual heading and the target heading based on the at least one roughness condition; and
calculating the desired rotational velocity based on the filtered difference between the actual heading and the target heading.
16. The method of claim 11 , wherein the attitude are of the marine vessel includes roll measurements, and further comprising:
estimating the at least one roughness condition by calculating a variance of the roll measurements;
filtering the difference between the actual heading and the target heading and the actual rotational velocity based on the variance of the roll measurements; and
calculating the desired rotational velocity based on the filtered difference between the actual heading and the target heading.
17. The method of claim 11 , further comprising setting the desired rotational velocity to zero in response to the difference between the actual heading and the target heading being inside a predefined heading difference hysteresis band.
18. The method of claim 17 , further comprising determining the heading difference hysteresis band based on the at least one roughness condition.
19. The method of claim 11 , wherein operating the propulsion system to move the marine vessel to minimize the difference between the desired rotational velocity and the filtered actual rotational velocity comprises calculating marine vessel movements that will minimize the rotational velocity difference using a feedback control algorithm; and
determining a gain for use in the feedback control algorithm based on the at least one roughness condition.
20. The method of claim 11 , further comprising:
calculating a desired linear velocity based on a difference between an actual global position of the marine vessel and a target global position at which the marine vessel is to be maintained;
filtering an actual linear velocity of the marine vessel based on the at least one roughness condition;
operating the propulsion system to move the marine vessel to minimize both the difference between the desired rotational velocity and the filtered actual rotational velocity and the difference between the desired linear velocity and the filtered actual linear velocity.