Nonlinear Output Feedback Control of Flexible Rope Crane Systems With State Constraints

When the suspension rope of the crane system is relatively long and its mass cannot be simply ignored compared with that of the payload, or when the crane rope is underwater, it will exhibit flexible characteristics, that is, the bending deformation will occur during swing. Undoubtedly, unreasonable bending deformation of the crane rope will further excite larger-amplitude payload swing, which will seriously influence the efficiency and safety. To this end, for flexible rope crane systems, this paper carries out in-depth analysis and puts forward an effective control method. Specifically, by introducing the concept of lumped mass method and virtual spring, a nonlinear dynamic model is established. Furthermore, in order to solve the problem that velocity signals are not measurable, a nonlinear control strategy, which does not need velocity signals for feedback, is proposed in this paper. Finally, rigorous theoretical analysis and a series of experimental results verify the effectiveness of the proposed control strategy.