Seeker-M: A bionic mantis shrimp robot with an adjustable-mass flexible spine

Abstract To enhance the motion flexibility and environmental adaptability of underwater robots, this study proposes a novel design, Seeker-M, inspired by the locomotion mechanism of the mantis shrimp. The robot imitates the mantis shrimp’s multi-pleopod swimming mode and has multi-modal locomotion ability. The robot features a multifunctional flexible spine capable of active bending (maximum angle of 30°) and dynamic center of gravity adjustment (up to 30% of body length). A pitch control system is developed based on this adjustable structure, employing the linear active disturbance rejection control (LADRC) algorithm. Experimental results demonstrate that the LADRC algorithm maintains robust attitude stability under disturbances from pleopod motion, offering an effective approach for underwater attitude control in complex environments.