| Recently, with the rapid development of the underwater robots, a variety of robots have been carried out. At the same time, the related research has achieved remarkable achievements. At present, the research institutions and laboratories have been devoted to the development and applications of underwater robots, which are due to widely apply in kinds of fields, such as fishery industry, collecting data, submarine salvage and military field etc. Underwater robots became an important tool for people to know, develop and use. Underwater robots could move in the water with vision and perception system to be as a modern high technology tool. It plays a key role in protecting the marine environment, marine economy development, development of marine resources whose importance is no less than the effect of rocket in the space exploration.Amphibious spherical robots are a kind of underwater robots. It can not only walk on land but also horizontal motion and rotate in the water. Amphibious spherical robot is researched in this paper using the design of symmetric structure, with high stability, small volume, it owns high stability that makes it be able to detect in some narrow seas and pipeline to collect data. As a maritime communication node, multiple robots can provide the communication network services as the sea ship. Also, the robot has a large internal space to carry some small robots for tasks such as demining task and also maintain long endurance ability. In addition, the robot has low noise that can provide helps for military. As a result, the amphibious spherical robot has wide application prospect and development value.In this paper, we present an amphibious spherical robot, which consisted of spherical shell, acrylic disc and four propulsion units, each of which contains two sevro motors and one water-jet propeller. The walking speed of the robot on land can be changed by regulating the driving frequency of servo motor and motion sequence of driving leg. The controller of the spherical amphibious robot is controlled by AVR single chip and the attitude of the robot can be controlled by adjusting duty ratio of output PWM.This paper analyzes and discusses the external structure of the spherical amphibious robot. Also, the control circuit board of the robot is designed according to the characteristics of amphibious spherical robot. This paper focuses on the characteristic analysis on land for an amphibious spherical robot. Robot can achieve a variety of gaits on land such as crawling gait and trotting gait by utilizing four legs with two Degrees of Freedom(DOF), together with utilizing a series of experiments to evaluate the walking motion in different terrains,step sizes and loads. Also, the model between the robot’s motion frequency and speed has been established using the numerical calculus and derivation. A platform has been set up to measure relationship between actuating force of single water-jet and the voltage for amphibious spherical robot. By adjusting size of PWM output from the AVR controller, the actuating force size of the robot can be changed. At the same time, by adjusting the deflection angle of the servo motor, the underwater robot motions can be changed. In addition, a series of experiments including underwater motions have also been carried out to evaluate its motions performance. Finally, some experiments have been carried out. The robot can implement some motions such as walk and rotate on land and move forward and backward, rotate and float up and float down in the water. The experimental results verify that it is the feasible to control system of the amphibious spherical robot. |
PDF Full Text Request