An adaptive nonsingular fast terminal sliding mode control scheme with extended state observer (ESO) is proposed for the trajectory tracking of an underwater vehicle-manipulator system (UVMS), where the system is subjected to the lumped disturbances associating with both parameter uncertainties and external disturbances. The inverse kinematics for the system is obtained by the quaternion-based closed-loop inverse kinematic algorithm. The proposed controller consists of the modified nonsingular fast terminal sliding mode surface (NFTSMS) and ESO, and the adaptive control law. The utilized NFTSMS can ensure the fast convergence of the tracking errors, together with avoiding the singularity in the derivation. According to the ESO method, the estimation error of the lumped disturbance vector can realize the fixed-time convergence to the origin, along with replacing the sign function with the saturation function to attenuate the chattering. A continuous fractional PI-type robust term with adaptive laws is introduced to handle the unknown bound of the estimation error. The closed-loop system is proved to be asymptotically stable by the Lyapunov theory. Simulations are performed on a ten degree-of-freedom UVMS under four different strategies. Comparative simulation results show that the proposed controller can achieve better tracking performance and stronger robustness of the disturbance rejection.

中文翻译：

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具有扩展状态观测器的水下机器人系统的自适应非奇异快速终端滑模跟踪控制

提出了一种具有扩展状态观测器（ESO）的自适应非奇异快速终端滑模控制方案，用于水下车辆操纵器系统（UVMS）的轨迹跟踪，该系统受到集总扰动的影响，该集总扰动既与参数不确定性又与外部扰动相关联。该系统的逆运动学是通过基于四元数的闭环逆运动学算法获得的。所提出的控制器由改进的非奇异快速终端滑模面（NFTSMS）和ESO组成，以及自适应控制律。利用的NFTSMS可以确保跟踪误差的快速收敛，同时避免推导中的奇异性。根据ESO方法，集总干扰矢量的估计误差可以实现到原点的固定时间收敛，以及用饱和度功能替换符号功能以减弱颤动。引入具有自适应律的连续分数PI型鲁棒项来处理估计误差的未知范围。李亚普诺夫理论证明了闭环系统是渐近稳定的。在十种自由度的UVMS下，采用四种不同策略进行了仿真。对比仿真结果表明，所提出的控制器具有较好的跟踪性能和较强的抗扰性鲁棒性。李亚普诺夫理论证明了闭环系统是渐近稳定的。在十种自由度的UVMS下，采用四种不同策略进行了仿真。对比仿真结果表明，所提出的控制器具有较好的跟踪性能和较强的抗扰性鲁棒性。李亚普诺夫理论证明了闭环系统是渐近稳定的。在十种自由度的UVMS下，采用四种不同策略进行了仿真。对比仿真结果表明，所提出的控制器具有较好的跟踪性能和较强的抗扰性鲁棒性。