Stability Analysis of Lifting Rigs—Part 1: Necessary and Sufficient Conditions

Abstract

When heavy equipment is moved by cranes or derricks—for example, in the course of manufacturing, assembly, or installation—the rigging or hitch used should be stable, i.e., it should not dump the load in the course of its motion. A general criterion is derived which is necessary and sufficient for Liapunov stability or asymptotic stability of a hitch. The relationship between asymptotic stability and stability under persistent disturbances is discussed, and an analytical expression for the system margin of stability is obtained.