| 摘要 |
An improved marine compass employs a Hall-effect device which provides an output signal related to the relative rotation of the compass card therein. When the Hall-effect device is mounted on a course dial whose position with respect to the compass' lubber line indicates a desired course, the output signal may be used as an input to an autopilot system. The system includes a DC constant current supply for the Hall-effect device, and an integrated circuit operational amplifier for amplifying said output signal to provide an angle signal having a usable level. A differentiator including a second IC operational amplifier provides a rate signal from the angle signal. A rudder signal is provided by a rudder position sensor employing a second Hall-effect device and a third IC operational amplifier. The angle and rate signals are combined and supplied with the rudder signal to a variable-threshold differential amplifier which in turn provides a control signal to a steering servomotor to modify the rudder position so as to return the vessel to its desired course. To allow high rates of rudder positioning without overshoot, a null damper circuit varies the threshold of the differential amplifier to pulse modulate the control signal at small values thereof. By replacing the marine compass with a manual control employing a Hall-effect device, the system operates as a remote steering system. |
