Automatic steering apparatus and method for small watercraft
First Claim
1. In a watercraft having a current heading, a control system having a variable-speed pump pumping hydraulic fluid through a double-acting hydraulic cylinder to move a piston therein that is coupled to a steering actuator that causes the current heading to change to a desired heading, an improvement comprising:
- a rate sensor generating a yaw rate signal;
a control subsystem storing the desired heading, determining from the desired heading and the current heading a heading error, and combining the heading error with the yaw rate signal to generate a turning rate signal; and
a hydraulic subsystem causing the piston to move in a direction and at a rate commanded by the turning rate signal.
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). An 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, or alternatively, a rate sensor (302) generates the yaw rate feedback signal directly. 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 a steering actuator (38) of an outboard motor (18).
58 Citations
17 Claims
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1. In a watercraft having a current heading, a control system having a variable-speed pump pumping hydraulic fluid through a double-acting hydraulic cylinder to move a piston therein that is coupled to a steering actuator that causes the current heading to change to a desired heading, an improvement comprising:
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a rate sensor generating a yaw rate signal; a control subsystem storing the desired heading, determining from the desired heading and the current heading a heading error, and combining the heading error with the yaw rate signal to generate a turning rate signal; and a hydraulic subsystem causing the piston to move in a direction and at a rate commanded by the turning rate signal. - View Dependent Claims (2, 3, 4)
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5. An automatic steering system for a watercraft, comprising:
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an electric compass providing current heading data associated with the watercraft; a rate sensor generating 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 positive displacement pump to move a piston rod within a hydraulic cylinder at a rate proportional to the steering rate command; 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 (6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of automatically steering a watercraft, comprising:
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providing current heading data associated with the watercraft; generating a yaw rate signal; storing desired heading data; determining from the desired heading data and the current heading data a heading error; combining the heading error with the yaw rate signal to generate a steering rate command; and moving a steering actuator at a rate proportional to the steering rate command to cause the watercraft to hold the desired heading. - View Dependent Claims (15, 16, 17)
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Specification