Study On A Multi-functional Amphibious Father-son Robot System

Currently,the underwater robots are playing a more and more critical role in the biomedical and naval fields such as underwater environment investigation,rescue or artificial environment maintenance as the increasing development of the underwater mechanism,sensing technology and control algorithms.Also,a number of motor-based actuating mechanisms were developed and the motor-based underwater robots can provide high output power and long sustainable time,which allows for high design flexibility.However,the motors limit the compact structure of the robots,because the electromagnetic structure of traditional motors is difficult to shrink.Thus,significant progress in research into biomimetic microrobots using piezoelectric actuators,shape memory alloy(SMA)actuators,polymer actuators,and ionic conducting polymer film(ICPF)actuators has been reported,for example the artificial muscles,which paved the way for a large variety in microrobot design.The robots actuated by smart actuators possess the attributes of compact structure,low noise and the precision of control,while the moving ability and endurance time of that is poor.Although the biomimetic microrobots driven by smart actuators have been researched for several years,it is still difficult to develop a microrobot with compact structure,flexibility,and multi-functions.That is because that these characteristics conflicts each other.For this reason,most microrobots abandon their compact structure,and use the biomimetic multi joints structure to improve flexibility and obtain multi-functions.While in pursuit of the miniaturization,other microrobots choose to give up the flexibility and multi-functions.To realize the multifunction of the microrobot aiming at adapting to the complex underwater environments,an insect-inspired microrobot which has two kinds of motion forms is proposed in this paper.The microrobot uses eleven ICPF actuators for locomotion and missions,and two SMA actuators for change of form.By having the compact structure,the microrobot can work in narrow spaces under the water.In order to solve the problems of limitations of locomotion velocity and enduring time for the microrobots,a father-son robot cooperation system is proposed in this research.A conceptual structure of a novel amphibious spherical robot is designed as the father robot for carrying the microrobots as son robots for collaboration.The spherical father robot is composed of a sealed hemispheroid,two openable quarter spherical shells,a plastic circular plate,a plastic shelf and four actuating units.Each unit consisted of a water jet propeller and two servo motors,each of which can rotate 90o in horizontal and vertical direction respectively.The robot can perform walking and rotating motions on land,as well as moving forward and backward,rotating,rising and sinking motions under the water.In this thesis,several important problems have been dealt with.Firstly,in order to develop a compact,multi-functional and flexible microrobot,an insect-inspired microrobot with change of form is proposed.Secondly,a close-loop control system for the microrobot is developed by using three proximity sensors.Thirdly,a father-son cooperation system is proposed and an amphibious spherical father robot is developed.Fourthly,a closed-loop control system for the spherical robot is presented to achieve high stability.Lastly,the land and underwater experiments are conducted to evaluate the performance of the robot system.