A Novel Obstacle Avoidance Consensus Control for Multi-AUV Formation System

In this paper, the fixed-time event-triggered obstacle avoidance consensus control for a multi-AUV time-varying formation system in a 3D environment is presented by using an improved artificial potential field and leader-follower strategy(IAPF-LF). Firstly, the proposed fixed-time control can achieve the desired multi-AUV formation within a fixed settling time in any initial system state. Secondly, an event-triggered communication strategy is developed to govern the communication among AUVs, and the communication energy consumption can be decremented. The time-varying formation obstacle avoidance control algorithm based on IAPF-LF is designed to avoid static and dynamic obstacles, the desired formation is maintained in the presence of external disturbances, and there is no Zeno behavior under the fixed-time event-triggered consensus control strategy.The stability of the system is proved by the Lyapunov function and inequality scaling. Finally, simulation examples and water pool experiments are reported to verify the performance of the proposed theoretical algorithms.

Development of Specific SSR Molecular Marker of "Huangzhou Radish" Based on Purity Identification

As an excellent local crop variety of Huanggang,"Huangzhou radish" has been widely promoted and its market influence is increasing day by day.Recently,the purity of "Huangzhou radish" has declined deeply,so it is urgent to improve and strengthen the purity and viability of "Huangzhou radish" including bad phenomena such as degeneration of varieties after self-pollination.At present,there was no SSR molecular marker can be used for genetic diversity identification of "Huangzhou radish".SSR molecular marker can provide a favorable tool to study "Huangzhou radish".In this study,"Xiakang","Hongbao"and "Huangzhou radish" were used as experimental materials,100 SSR primers were screened,and 25 pairs of SSR primers were selected.Finally,two pairs of primers were selected for identification of the purity of "Huangzhou radish" by non-denatured polyacrylamide gel electrophoresis (PAGE).The results showed that R-102 and R-112 primer pairs could amplify the special bands for "Huangzhou radish" from above three kinds of radishes.These two pairs of primers could be developed as SSR markers to identify the specificity and purity of "Huangzhou radish".Furthermore,this study provides convenient conditions for promoting the economic and social value of "Huangzhou radish".

Modeling and Simulation of Automatic Berthing based on Bow and Stern Thruster Assist for Unmanned Surface Vehicle

In order to solve the technical problems of autonomous berthing of the Unmanned Surface Vehicle(USV),this research has met the requirements of maneuverability berthing under different conditions by effectively using the bow and stern thrusters,which is a technological breakthrough in actual production and life.Based on the MMG model,the maneuverability mathematical model of the USV with bow and stern thruster was established.And the motion simulation of USV maneuvering was carried out through the numerical simulation calculation.Then the berthing plan was designed based on the maneuverability analysis of the USV low-speed motion,and the simulation of automatic berthing for USV was carried out.The research results of this paper can be of certain practical significance for the USV based on the support of the bow and stern thruster in the berthing.At the same time,it also provides a certain theoretical reference for the handling of the USV automatic berthing.