Stability of Auto-Piloting

The present paper relates to stability problem of auto-piloting of ships with particular reference to “weather adjust” mechanism which induces sometimes a self-exciting severe yawing.Kochenburger's stability criterion may be utilized for analyzing steering systems involving “weather adjust” mechanism, helm-angle limitation and other non-linear elements. In conclusion, it may be strongly recommended to employ “dead band” element for weather adjust mechanism in place of “back lash” element which has been widely used conventionally. On the other hand, ang-ular velocity control, that means to operate a rudder reacting to angular rate of course deviation as well as to course deviation itself, is decidedly superior to another damping means, “over telemotor adjust” so-called. The synthesis of the angular velocity control may be carried out through Nyquist criterion.