| 摘要 |
<p>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. The performance index derived during a given measurement interval is compared with the index derived in the previous interval and a counter register is set according to the results of this comparison. The heading keeping circuit receives heading error signals which are processed in a first proportional channel and also differentiated and processed in a second or rate channel. The attenuation in each channel is adjusted in accordance with the value stored in the counter register. The attenuation in the rate channel is made equal to the square root of the attenuation in the proportional channel. The modified rate and proportional signals are added to obtain the final rudder order signal.</p> |
