Xichuan Lin

Development of a Spherical Underwater Robot Equipped with Multiple Vectored Water-Jet-Based Thrusters.

Research on underwater robots is attracting increased attention around the world. Various kinds of underwater robots have been developed, using an assortment of shapes, sizes, weights, and propulsion methods. In this paper, we propose a novel underwater robot, employing a spherical hull and equipped with multiple vectored water-jet-based thrusters. The overall design of the robot is first introduced, and the mechanical structure and electrical system are then individually described. Two important mechanical components are the spherical hull and the waterproof box, and these are discussed in detail. Detailed descriptions of the two-level architecture of the electrical system and the design of the water-jet thrusters are also given. The multiple vectored water-jet-based propulsion system is the key feature of the robot, and the experimental mechanism of this system is briefly explained. The three main principles behind the propulsion system are also presented. Finally, evaluation experiments are presented to verify the basic motions of a prototype robot. The experimental results demonstrate that the motion characteristics of this type of underwater robot are acceptable, and the design is worthy of further research.

Development and control of a vectored water-jet-based spherical underwater vehicle

This paper presents a spherical underwater vehicle which uses three vectored water-jet propulsion systems. In this paper, firstly, we proposed the concept of a vectored water-jet based spherical underwater vehicle. Then we give the basic design of this underwater vehicle. The working principles of the vectored water-jet propellers is illustrated including the transformation of reference frames, the distribution of propellers and the composition of vectored propel forces. Thirdly, we give the results of simulation experiment which compares traditional PID control and BP neural network based PID control. This control experiment only focus on the horizontal motion, but it can be expanded in the other control plane easily.

Underwater experiments of a water-jet-based spherical underwater robot

In this paper we present the underwater experiments for spherical underwater robot which is developed in our laboratory. First, we give a brief illustration for the dynamics modeling of single water-jet propeller. Then, the coordination of multiple water-jet propellers is introduced. Based on the coordination, we discuss the transforms of three basic motions, surge, heave and yaw. To evaluate the characteristics of these basic motions, we carry out different experiments for each basic motions. And finally, we give the experimental results and analysis for the results.

Analysis and improvement of the water-jet propulsion system of a spherical underwater robot

In this paper, we present the static analysis of a water-jet propulsion system. First, some previous researches in this field are introduced. Then, the motivation of static analysis is proposed. Based on that, we analyze the original mechanism that has been completed. After analyzing disadvantages of the mechanical structure of the propulsion system, improvement is carried out. We extend the motion range of water-jet thruster to +60°~-90°. Finally, the static analysis is carried out to improve the mechanical structure and compared the results with original design. The comparison result shows that about 50% deformation is declined. The static analysis is very useful to improve the propulsive accuracy of the water-jet propulsion system.

A conceptual design of vectored water-jet propulsion system

This paper presents a novel vectored water-jet propulsion system which is supposed to be used on a spherical underwater vehicle. This system uses water-jet as its propulsion method and by using servo motors, the direction of output force can be regulated for different propulsion tasks. This paper mainly focuses on the conceptual design of the system. To testify the availability of this design, a physical-based vectored water-jet propulsion system is developed using MATLAB/Simscape. Firstly, the servo motors module and flow rate control module are discussed respectively including modeling and simulation, and then a combined simulation of them is performed.

An improved 3D modeling of water-jet propellers for a spherical underwater robot

This paper presents a newly improved 3D modeling of multiple water-jet propellers which is used inside a spherical underwater robot. For a start, the whole structure of the robot is illustrated briefly. To overcome undesirable properties of the 2D modeling, a more accurate modeling is designed instead of the previous one, which adopts one 6-axis load cell sensor to detect propulsive forces in the x, y, z-axis directions and torques simultaneously. Afterwards, a series of underwater experiments are carried out to figure out the closed relations between the regulating angles in horizontal plane and vertical plane and the forces and moments generated by single propeller in the robot. These experimental results showed that the advanced propulsion system is much more appropriate for studying on underwater robots.

Development of a spherical underwater robot

This paper presents a spherical underwater robot which uses three vectored water-jet propellers as its propulsion system. In this paper we introduced the conceptual design of the spherical underwater robot including the hull, waterproof chamber, propulsion system. Then we develop a prototype of this spherical underwater robot. Finally, we carry out confirmatory experiments to verify the availability of the design of the spherical underwater robot.

Adaptive fuzzy sliding mode control for spherical underwater robots

An adaptive fuzzy sliding mode controller is proposed to deal with the depth and heading regulation of spherical underwater robots. The performance of the proposed controller is investigated in simulation. The controller can realize a better control of the spherical underwater robots. Furthermore, the designed controller can not only tolerate actuator stuck faults, but also compensate the disturbances with constant components. Also, the controller is easy for engineering realization. The controller is not specific to such a system and is applicable to a reasonably wide class of engineering systems which can, at least in an operating region of interest, be adequately represented.

Modeling of water-jet propeller for underwater vehicles

Propeller is the most important part in a underwater vehicle system. An accurate modeling of the propulsion system is necessary. In this paper, we discuss about the modeling of water-jet propeller which will be used on a spherical underwater vehicle. By considering the ambient flow velocity and the incoming angle of the flow, we designed an experiment, and obtained the dynamic model of the water-jet propeller.

A neural network-based self-tuning PID controller of an autonomous underwater vehicle

Taking into account the complex interferences in underwater environment, this paper presents a neural network-based self-tuning PID controller for a spherical AUV. The control system consists of neural network identifier and neural network controller, and the weights of neural networks are trained by using Davidon least square method. The proposed controller is characterized with a strong anti-interference ability and a fast convergence rate. For its simple structure, the controller can be easily realized in hardware. The linear velocity of the spherical AUV can be controlled to precisely track any desired trajectory in vehicle-fixed coordinate system. The effectiveness of the controller is verified by simulation results.