Research On Glide Control Method Of Bionic Robot Crab

As China continues to build itself into a maritime power,more and more offshore platforms are being built in China’s territorial waters.Since offshore platforms can be damaged by complex ocean conditions,regular monitoring of offshore platforms is essential.As a robot with underwater crawling ability,bionic robot crab can be flexible and stable close to the ocean platform,and then complete the close-range observation and structural flaw detection.However,due to the poor maneuverability of underwater crawling,the autonomous movement efficiency of the bionic robot crab between multiple offshore platforms is low.A novel bionic robot crab was proposed in " the Research on Key Technologies of New Concept Bionic Amphibian Robot Crab " supported by National Natural Science Foundation of China.Based on the traditional bionic robot crab,it adds the gliding function,which can achieve low energy consumption and autonomously move between offshore platforms.However,since most of the offshore platforms are built in the offshore area,the vertical distance for gliding is limited.Therefore,the bionic robot crab needs to drive the buoyancy system and the attitude system to do work in a short period,which makes the overall gliding efficiency low.In order to improve the glide efficiency in the limited vertical motion space,vertical plane glide controllers with fixed-time convergence performance are designed for the bionic robot crab.Firstly,a T-S fuzzy sliding mode controller is designed for the bionic robot crab.The controller is designed based on the fixed-time controller,which can make the state of bionic robot crab converge in a fixed time.Compared with the fixed-time controller,the controller can reduce chattering effectively and ensure the control performance.In addition,considering the actuator saturation of the bionic robot crab,a saturation auxiliary system is designed to reduce the influence of actuator saturation.By using Lyapunov stability theory and numerical simulation,the effectiveness of the proposed control algorithm is verified.Secondly,considering the model uncertainties and external disturbances,an adaptive fixed-time integral sliding mode controller is designed.This controller can make the bionic robot crab converge in a fixed time and suppress chattering.And the adaptive law can effectively solve the problems caused by model uncertainty and external disturbance.In addition,a saturation auxiliary system is used to reduce the influence of actuator saturation.The effectiveness of the adaptive fixed-time integral sliding mode controller is verified by mathematical proof and simulation.Finally,considering the above considerations,the influence of speed-sensorless conditions and state delay,a fast fixed-time controller based on adaptive extended state observer is designed.The adaptive extended state observer and fast fixed-time controller are designed based on a fast fixed-time convergence system.Compared with the existing fast fixed-time convergence system,the convergence time of this system is shorter.The extended state observer can make up for the lack of unmeasured velocity and reduce the influence of lumped disturbances.In addition,a saturation auxiliary system and an advance prediction method are used to reduce the influence of actuator saturation and state delay.The controller is analyzed by Lyapunov stability theory,and the rationality and effectiveness of the proposed control strategy are verified by numerical simulation.