Abstract: A marine auto pilot employing a compass with a Hall-effect sensing element in conjunction with a magnetic circuit designed to provide a high intensity magnetic field; electrical circuitry designed to produce high servo-loop gain at frequencies lower than the normal sea wave frequencies, and lower gain at the normal sea wave frequencies; a D.C. Linear Motor drive system in conjunction with a rudder position feedback signal; and a linear ball-screw and nut gearing system for converting the high-speed output of the direct current drive motor to a low-speed high-torque drive at the rudder, having the nut and ball-screw connected through rolling contact balls.

Abstract: An electromagnetic drive for rotary bodies including a stationary member having at least two coils and a revolving member arranged for rotation with respect thereto. The coils are supplied with a current signal for causing rotation of the revolving member and a sensing arrangement senses the position of the revolving member with respect to the stationary member and provides an output indicative thereof. A control device is responsive to the output of sensing arrangement for supplying an additional current signal to the coils effect positional control of the revolving member.

Abstract: An apparatus capable of digitizing or plotting coordinate locations and lines utilizes an automatically controlled carriage that is translated over the supporting surface of a digitizing and plotting table and a free cursor for identifying specific coordinate locations on the table. Radiation means, such as electromagnetic coils, are mounted on the carriage and the cursor to produce signals indicative of the relative positioning of the carriage and cursor during a digitizing mode of operation. The position signals are transmitted to controlled drive motors which cause the carriage to follow the cursor over the supporting surface. Encoders, also operated by the drive motors, allow the position of the carriage and, hence, the cursor to be recorded for subsequent usage. A plotting instrument such as a pen is mounted on the carriage so that the apparatus can be used in a plotting mode of operation to generate graphic information.

Abstract: An automatic steering system for vessels, operational in a manual mode to select a desired heading, and in an automatic mode to maintain the selected heading. In the manual mode, a magnetic compass incorporated in a servo loop is maintained at a null position to continually monitor the vessel heading. When the system is switched to the automatic mode, the compass servo loop is deactivated and a control loop activated. The control loop keeps the compass output at null by maintaining the vessel on the selected heading. Automatic course corrections are accomplished by turning the helm an amount proportional to a deviation signal, and immediately returning the helm to its original position less a small preset angle. A wireless remote control unit affords the capability of remotely steering the vessel, selecting a new course, and switching between automatic and manual modes.

Abstract: 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.