Underwater robots play a crucial role in exploring aquatic environments. The ability to flexibly adjust their attitudes is essential for underwater robots to effectively accomplish tasks in confined space. However, the highly coupled six degrees of freedom dynamics resulting from attitude changes and the complex turbulence within limited spatial areas present significant challenges. To address the problem of attitude control of underwater robots, this letter investigates large-range pitch angle tracking during station holding as well as simultaneous roll and yaw angle control to enable versatile attitude adjustments. Based on dynamic modeling, this letter proposes an adaptive integral sliding mode controller (AISMC) that integrates an integral module into traditional sliding mode control (SMC) and adaptively adjusts the switching gain for improved tracking accuracy, reduced chattering, and enhanced robustness. The stability of the closed-loop control system is established through Lyapunov analysis. Extensive experiments and comparison studies are conducted using a commercial remotely operated vehicle (ROV), the results of which demonstrate that AISMC achieves satisfactory performance in attitude tracking control in confined space with unknown disturbances, significantly outperforming both PID and SMC.

翻译：水下机器人在探索水环境方面发挥着关键作用。灵活调整姿态的能力对于水下机器人在受限空间内有效完成任务至关重要。然而，姿态变化引起的六自由度高度耦合动力学以及有限空间内的复杂湍流带来了重大挑战。为解决水下机器人的姿态控制问题，本文研究了驻留期间的大范围俯仰角跟踪以及同时进行的横滚和偏航角控制，以实现灵活的姿态调整。基于动力学建模，本文提出了一种自适应积分滑模控制器（AISMC），该控制器将积分模块融入传统滑模控制（SMC），并自适应调整切换增益，以提高跟踪精度、减少抖振并增强鲁棒性。通过Lyapunov分析确立了闭环控制系统的稳定性。使用商用遥控水下航行器（ROV）进行了大量实验和对比研究，结果表明AISMC在受限空间中未知干扰下的姿态跟踪控制中取得了令人满意的性能，显著优于PID和SMC。