Objective To improve the overall operational capability of autonomous underwater vehicles (AUVs) and address the critical issue of collision risks during the dynamic docking process between AUVs and towed recovery docks (TRDs), this study conducts a systematic investigation into the collision mechanisms and control strategies of the docking system. Reliable docking and recovery technology is essential for extending the operational endurance of AUVs, enhancing data transmission efficiency, and enabling long-term underwater residency. However, in practical marine environments, limitations in sensor accuracy, external environmental disturbances, and dynamic responses of the docking system often lead to unavoidable contact or collision between AUVs and TRDs, which may result in mission failure or structural damage to the equipment. Therefore, this research aims to clarify the influence of key initial operating conditions on docking collisions and propose an effective control strategy to optimize the dynamic docking process, thereby providing theoretical and technical support for the engineering application of AUV towed recovery systems.

Methods Based on dynamic analysis, a simulation model incorporating contact collision dynamics was established on the ADAMS-MATLAB co-simulation platform. First, rigid body dynamics models of AUV and TRD were constructed respectively, with the AUV model considering forces such as gravity, buoyancy, viscous hydrodynamic resistance, inertial hydrodynamic resistance, thrust, and environmental disturbances, and the TRD model adopting a frame-cage structure with a bell-mouth guide cover and using a discrete flexible body method for towing cable modeling. Then, a nonlinear contact model based on Hertz theory was employed to calculate the collision force between AUV and TRD, which more accurately reflects the transient impact characteristics of the collision process compared with the linear contact model. On this basis, the influence of initial operating conditions including eccentric angle, eccentric distance, relative initial velocity, and mother ship acceleration on the docking collision was systematically analyzed through the control variable method. To address the attitude disturbance caused by collisions, a multi-stage coordinated control strategy based on PID control was proposed, which realizes active attitude adjustment of AUV by switching control modes in different docking phases.

Results The simulation results reveal that increases in eccentric angle and eccentric distance primarily prolong the docking time while exerting limited influence on the peak collision force, with the peak collision force basically maintaining within the range of 1000–2000 N under most working conditions. In contrast, increasing the relative initial velocity can shorten the docking time but significantly amplifies the peak collision force, showing a positive correlation between them. The investigation into the mother ship’s acceleration further reveals the complex non-monotonic relationship between collision force and docking efficiency; as the mother ship’s acceleration increases, the attitude variation of the dock intensifies, leading to greater uncertainty in the collision position, and the peak collision force reaches its maximum value when the acceleration is 0.2 m/s². Moreover, the proposed multi-stage coordinated control strategy achieves active attitude adjustment of AUV after collision. In the case of uniform motion of the mother ship, the strategy reduces the peak collision force by up to 74.5% while shortening the docking time from 7.56 s to 5.93 s. Even under the complex working condition of uniform acceleration of the mother ship, the peak collision force is reduced by 19.6%, and the docking time is shortened by 16.7%, effectively optimizing the dynamic docking process and ensuring both docking safety and efficiency.

Conclusion This study systematically clarifies the influence laws of key initial operating conditions on the docking collision between AUV and TRD. The research findings indicate that controlling the initial eccentric angle and eccentric distance can improve docking efficiency, while adjusting the relative initial velocity and mother ship’s acceleration needs to balance the trade-off between collision risk and docking speed. The proposed multi-stage coordinated control strategy can significantly reduce the peak collision force while maintaining docking efficiency, with a reduction range of 14%–74.5% in different working conditions. This strategy exhibits strong robustness and stability compared with the traditional position tracking control strategy, effectively addressing the limitations of passive control relying solely on the dock structure. Overall, this study provides a reliable simulation basis and design reference for the design and stability control of AUV towed recovery systems, and the research framework and methods can also provide guidance for the collision analysis and control of similar underwater docking systems.