First-Order Theory of Control of Motion of a Crane and Load

A first-order mathematical model has been developed in a theoretical study of the dynamics of a load suspended by a cable from a crane that moves along a straight track. The model is the basis of a proposed method of computer control of the velocity as well as the position of the crane to minimize or prevent swinging of the load. (Traditionally, only the position of the crane is controlled; there is no engineering provision against swinging of the load.) Velocity and position control to prevent swinging would be highly desirable, especially in situations in which there are requirements for precise placement of large loads and/or the delays incurred in waiting for damping of pendulum oscillations of loads are unacceptable. Because most modern cranes are already controlled by computers and include position-indicating control subsystems, the implementation of this method of control would entail little or no additional equipment and thus should be relatively inexpensive.