Cooperative towing for double unmanned surface vehicles connected with a floating rope via vertical formation and adaptive moment control

The surface round-up and towing operations are essential for surface garbage removal, oil spill recovery and shipwrecked ship rescue. All of which are related to the national economy and the people's livelihood, and it is urgent to improve operation efficiency. This work considers connecting double unmanned surface vehicles (DUSVs) with floating ropes to achieve efficiently autonomous round-up and towing. The core of this research is how to realize autonomous cooperative towing control of DUSV under the interference of floating rope hydrodynamic moment and wind, wave and current. Therefore, a vertical formation control algorithm was proposed to improve the control performance of the DUSV. The virtual leader-follower was treated as the guidance target, and the relative distance between the DUSV and the guidance target should be maintained properly. Next, to reduce the probability of drag separation of DUSV, on the basis of the sensors equipped on the floating rope, an adaptive moment control algorithm was designed via the control of the heading angle error and the adjustment of the moment correction. The results of the simulation and water experiments verified the excellent performance of our algorithms.