A variety of microrobots have commonly been used in the fields of biomedical engineering and underwater operations during the last few years. Thanks to their compact structure, low driving power, and simple control systems, microrobots can complete a variety of underwater tasks, even in limited spaces. To accomplish our objectives, we previously designed several bio-inspired underwater microrobots with compact structure, flexibility, and multi-functionality, using ionic polymer metal composite (IPMC) actuators. To implement high-position precision for IPMC legs, in the present research, we proposed an electromechanical model of an IPMC actuator and analysed the deformation and actuating force of an equivalent IPMC cantilever beam, which could be used to design biomimetic legs, fingers, or fins for an underwater microrobot. We then evaluated the tip displacement of an IPMC actuator experimentally. The experimental deflections fit the theoretical values very well when the driving frequency was larger than 1 Hz. To realise the necessary multi-functionality for adapting to complex underwater environments, we introduced a walking biomimetic microrobot with two kinds of motion attitudes: a lying state and a standing state. The microrobot uses eleven IPMC actuators to move and two shape memory alloy (SMA) actuators to change its motion attitude. In the lying state, the microrobot implements stick-insect-inspired walking/rotating motion, fish-like swimming motion, horizontal grasping motion, and floating motion. In the standing state, it implements inchworm-inspired crawling motion in two horizontal directions and grasping motion in the vertical direction. We constructed a prototype of this biomimetic microrobot and evaluated its walking, rotating, and floating speeds experimentally. The experimental results indicated that the robot could attain a maximum walking speed of 3.6 mm/s, a maximum rotational speed of 9°/s, and a maximum floating speed of 7.14 mm/s. Obstacle-avoidance and swimming experiments were also carried out to demonstrate its multi-functionality.
Biomimetic underwater microrobots are of great interest for underwater monitoring operations, such as pollution detection and video mapping in restricted underwater environments. Generally speaking, compact structure, multi‐functionality, flexibility and precise positioning are considered incompatible characteristics for underwater microrobots. Nevertheless, we have designed several novel types of bio‐inspired locomotion, using ionic polymer metal composite (IPMC) and shape memory alloy (SMA) actuators. We reviewed a number of previously developed underwater microrobot prototypes that were constructed to demonstrate the feasibility of these types of biomimetic locomotion. Based on these prototypes, we summarized the implemented techniques and available results for efficient and precise underwater locomotion. In order to combine compact structure, multi‐functionality, flexibility and precise positioning, we constructed a prototype of a new lobster‐like microrobot and carried out a series of experiments to evaluate its walking, rotating, floating and grasping motions. Diving/surfacing experiments were performed by electrolyzing the water around the surfaces of the actuators. Three proximity sensors were installed on the microrobot to detect an object or avoid an obstacle while walking
Nowadays, microrobots are being widely researched in order to deal with complicated missions in limited spaces. But important abilities such as locomotion velocity and enduring time are usually sacrificed in order to realize compact sizes. To solve these problems, we proposed a mother-son multirobots cooperation system, named GSL system, which included several microrobots as son robots, and a novel designed amphibious spherical robot as the mother robot. The mother robot, which was called GSLMom robot, was designed to be able to carry microrobots and provide power supply for them. This paper will mainly focus on the structure and mechanism of the GSLMom robot. The GSLMom robot, which was designed as an amphibious spherical one, was shaped by a fixed hemisphere hull, and two openable quarter ball hulls. The robot was equipped with a 4 unit locomotion system, and each unit consists of a water jet propeller and two servo motors. Each servo motor could rotate 90 in horizontal or vertical direction respectively. When moving in water, servo motors controlled the directions of water jet propellers and the 4 propellers worked to actuate the robot. With this mechanism, the robot could realize moving forward, backward, rotating, floating and sinking motion in water. In the ground situation, propellers were used as legs, and servo motors actuated these legs to realize walking mechanism, so that the robot could realize moving forward, backward, and rotating motions on the ground. After discussed structures, actuating strategies were proposed for the robot. And kinematic models of the robot were also built.
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