Abstract: Heading keeping apparatus for a marine vessel autopilot that compares the RMS yaw to a plurality of yaw increments and compares the instantaneous yaw to a plurality of yaw increments to provide respective gain controlling signals in accordance with the increments in which the RMS yaw and instantaneous yaw resides. The gain controlling signal representative of the highest gain is selected to control the gain of the autopilot.

Abstract: A heading change unit for a ship's autopilot gyrocompass that provides a heading error signal to produce a proportional rudder control signal. An operator enters a heading change which causes an up/down counter to be incremented or decremented in accordance with the heading change order. The counter is also responsive to a step heading input signal. The count is referenced to a zero value and converted to an analog control signal by a digital-to-analog converter. As the ship turns towards the new heading, the changing step heading input will cause the counter to count back to zero. The displayed amount of heading error or ordered heading change is generated by converting the analog heading error signal to a digital encoded format which controls a display. The heading error signal is generated in the form of a parallel twelve bit binary code which represents integer degree changes and 1/6 degree fractional changes.

Abstract: An adaptive autopilot for Marine Vessles which seeks to obtain minimum combined hull and rudder drag while maintaining heading control by providing optimum rudder activity through a series of iterative steps.

Abstract: A control circuit for driving solenoids protects these devices from failure due to overheating caused by frequent on-off cycling. Control signals are passed through logic gates. A timer responds to the termination of a control pulse and disables the logic gate that passes signals to the load for a predetermined time, thus restricting the minimum off time of the solenoid. Minimum on time or maximum on or off times are not affected.

Abstract: The peaks of synchro or step data representative of compass heading are detected and the resulting logic levels are latched into a register by an enable pulse generated in response to the data itself. Three outputs from the register are fed directly to the computer input port and provide 1/6.degree. resolution and 1.degree. range. Two of the register outputs are decoded and used to operate an up/down counter. The output of the counter is applied to the computer input port and provide 1.degree. resolution and 16.degree. range.

Abstract: An apparatus for providing the operator of a marine vessel with an alarm when when a malfunction occurs in the steering system of the vessel. The apparatus utilizes a closed loop simulator to simulate the rudder position, and a comparison of the simulated rudder position to the actual rudder activates the alarm when a predetermined threshold value has been exceeded. Appropriate time delays during which the alarm is disabled make the apparatus adaptable for use with steering systems having a steering gear which has rate inconstancy, and a shaping circuit makes the apparatus adaptable for use with steering systems having a steering gear which has static positional nonlinearity.

Abstract: Direct current error signals of either polarity are converted to a unipolar voltage and used to offset a triangular timing wave. The offset wave is applied to threshold amplifier so as to produce pulse width modulated signals. The pulse width modulated signals, together with a polarized direction signal and a clock signal from the triangular wave source, is applied to a servo amplifier containing first and second channels, each containing a flip flop for opening the associated channel in accordance with the polarity of the direction signal so as to pass direct or inverted pulse width modulating signals, respectively, through amplifier and filter circuits to the output terminal. Each of the amplifier circuits has a current sensing resistor, and a switching transistor arranged to switch the associated flip flop and thereby open that channel whenever the current through the sensing resistor exceeds a predetermined level.

Abstract: An autopilot automatically adjusts the sensitivity of a ship's steering system to accommodate changes in speed as well as sea and wind conditions. The autopilot utilizes heading error, speed and speed squared signals to produce a rudder order signal for controlling rudder position. The rudder order signal is developed in a heading keeping circuit unless a heading change greater than a predetermined threshold is commanded, in which event a programmer substitutes a heading change circuit for the heading keeping circuit. The sensitivity of the heading change circuit is automatically adjusted as an inverse function of vessel speed squared, and automatic rudder order limits are established in the same circuit as an inverse function of speed. The sensitivity of the heading keeping circuit is adjusted in accordance with a signal from an automatic gain control circuit which derives a performance index J from ship's speed, heading error and rudder order signals occurring during a given measurement interval.

Abstract: Apparatus for detecting malfunctions in rudder-type steering systems utilizes electrical order and rudder angle signals. The rudder-order signal is applied to a closed-loop simulator that includes integrating apparatus adjusted to provide a time-variant simulated rudder angle signal which varies in the same manner that the actual rudder angle signal would vary in the absence of a malfunction when exposed to the same rudder error signal. The simulated and actual rudder angle signals are compared in a summing amplifier whose output is applied to a thresholding circuit which actuates an alarm whenever the instantaneous values of the simulated and actual rudder angle signals differ by more than a predetermined amount.

Abstract: An apparatus for coupling digital data from a data generator to a readout device and providing electrical isolation therebetween. The apparatus including a control signal generator which couples digital data, representative of the data from the data generator, to a switch which responds thereto and couples data representative thereof to an isolation device. Operation of the switch is performed without external voltage supplies, all switching being accomplished entirely with the voltages coupled from the control signal generator to the switch. The isolation device converts the electrical signals to light signals that are then coupled to a light sensitive device which converts the light signals to digital electrical signals for coupling to the readout device.