Objective Inspired by remora, a robotic remora that can adhere to diverse hosts and travel with them over long distances with low energy consumption due to its unique adhesion ability, addresses the issue of low endurance in the robotic fish.

Methods A prototype with decoupled three-dimensional motion, high mobility, and responsive vertical motion has been developed. Moreover, a wire-driven propulsion mechanism and a pectoral fin ascending and descending mechanism have been adopted to achieve high mobility and decoupled motion. Additionally, a central pattern generator (CPG) is adopted to realize high biomimetic swimming postures and smooth switching between motion modes. An active disturbance rejection controller (ADRC) is developed to achieve robust, fast and precise heading control under model uncertainty and the environment disturbance. The swimming, diving and heading control experiments are conducted.

Results The results exhibits that the designed robotic remora owns the high mobility and responsive decoupled motion capabilities, with the maximum swimming speed of 0.17 m/s and max ascent and descent speed of 0.095 and 0.099 5 m/s respectively. The designed ADRC heading controller can achieve fast and precise control, which is with better performance than the PID controller.

Conclusion This study, which presents the design of the robotic remora and verifies the decoupled motion and the ADRC heading controller by experiments, lays the foundation for the auto adhesion of the robotic remora.