Small watercraft automatic steering apparatus and method
First Claim
1. An automatic steering system for a watercraft, comprising:
- an electric compass providing current heading data associated with the watercraft;
a rate taker generating from the current heading data a yaw rate signal;
a yaw rate control loop storing desired heading data, determining from the desired heading data and the current heading data a heading error, and combining the heading error with the yaw rate signal to generate a steering rate command;
a steering control loop receiving the steering rate command and causing a pump motor and a pump coupled thereto to rotate at a rotational speed commanded by the steering rate command such that a hydraulic fluid is pumped through a hydraulic cylinder to move a piston rod at a rate proportional to the rotational speed of the pump; and
a mechanical link connecting the piston rod to a steering actuator such that the steering rate command causes the piston rod to move the steering actuator in a manner that causes the watercraft to hold the desired heading.
2 Assignments
0 Petitions
Accused Products
Abstract
An automatic steering system (10) has a control subsystem (14) that employs a yaw rate control loop (90) and a steering control loop (92) to drive a hydraulic subsystem (12) in which the deflection rate of a steering actuator (16) is controlled without need for either a steering actuator angle sensor or an electronic steering bias integrator. Rather, the control subsystem employs a proportional rate servosystem to control the steering actuator deflection rate and a double-acting hydraulic cylinder (34) to provide the steering bias integral action. The control subsystem employs an electric compass (96) to generate heading data that are stored in a heading command register (102). A heading error is formed by calculating a difference between a desired heading and the current heading. A rate taker (94) generates a yaw rate feedback signal by differentiating changes in the current heading. The heading error and yaw rate feedback signal are processed to generate a steering rate command to which the steering control loop responds by pumping hydraulic fluid at a rate proportional to the steering rate command into the hydraulic cylinder to deflect the steering actuator of an outboard motor (18).
-
Citations
15 Claims
-
1. An automatic steering system for a watercraft, comprising:
-
an electric compass providing current heading data associated with the watercraft; a rate taker generating from the current heading data a yaw rate signal; a yaw rate control loop storing desired heading data, determining from the desired heading data and the current heading data a heading error, and combining the heading error with the yaw rate signal to generate a steering rate command; a steering control loop receiving the steering rate command and causing a pump motor and a pump coupled thereto to rotate at a rotational speed commanded by the steering rate command such that a hydraulic fluid is pumped through a hydraulic cylinder to move a piston rod at a rate proportional to the rotational speed of the pump; and a mechanical link connecting the piston rod to a steering actuator such that the steering rate command causes the piston rod to move the steering actuator in a manner that causes the watercraft to hold the desired heading. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. In a watercraft having a control system in which a variable-speed pump pumps hydraulic fluid through a double-acting hydraulic cylinder to move a piston therein that is coupled to a steering actuator that determines a current heading, an improved automatic steering method comprising:
-
generating a turning rate signal; pumping fluid into the hydraulic cylinder to move the piston in a direction and at a rate proportional to the turning rate signal; detecting a yaw rate of the watercraft and generating therefrom a yaw rate signal; and feeding the yaw rate signal back to the generating step to regulate the turning rate signal. - View Dependent Claims (13, 14, 15)
-
Specification