Fish-Like Robot Encapsulated by a Plastic Film

Underwater robots are currently utilized to evaluate water quality and the undersea landscape. Small-sized underwater robots are especially useful in improving the spatial resolution of the measurements, yielding high-quality data. This chapter describes a small-sized fish-like robot, with its surface composed of a flexible thin plastic film. Its internal components, including an actuator, could be encapsulated in the plastic film using a vacuum packaging machine. To simplify the waterproofing and pressure resistance properties of the fish-like robot, its internal components can be filled with insulating fluid. The plastic film on the surface has electromagnetic-wave-transmitting properties, allowing sensors to be arranged within the device, enabling assessment of its autonomous locomotion using infrared sensors. Robot attitude can be altered, based on geography of its internal components, floating blocks, and insulating fluid. This attitude could be especially determined by the differences in densities between the floating block and insulating fluid. Evaluation of attitude control showed that an insulating fluid heavier than water allows a large variation

Dynamic Modeling of a Serial Link Robot Laminated with Plastic Film

This chapter presents serial link robots laminated with a plastic film, a derivation of the equations of motion of the laminated robots, and numerical simulation. Recently, to become capable of wide application for several serial link robots that work outside, waterproofing and dustproofing techniques are required. We have proposed a robot packaging method to improve waterproof and dustproof properties of serial link robots. Using the proposed packaging method, rigid links with some active joints are loosely laminated with plastic film to protect the links from dust and water. In the next step of our research, we must derive the equations of motion of the laminated robots for the design and performance improvement from the viewpoint of high speed and high energy efficiency. We assume a plastic film as a closed-loop link structure with passive joints in this chapter. A rigid serial link (fin) connected with a motor-actuated joint moves a closed-loop link structure with passive joints. We numerically investigate the influence of the flexural rigidity of a plastic film on the motion of the rigid fin. This research not only contributes to the lamination techniques but also develops a novel application of waterproofing and dustproofing techniques in robotics

Swimming of onboard-powered autonomous robots in viscous fluid filled channels

Microrobots can make a great impact in medical applications such as minimally-invasive surgery, screening and diagnosis of diseases, targeted therapy and drug delivery. Smallsized bio-inspired robots can mimic flagellar propulsion mechanisms of microorganisms for actuation in microfluidic environments, which are dominated by viscous forces. Microorganisms propel themselves by means of the motion of their flagella such as rotation of rigid helices or travelling planar waves on flexible tails similar to whipping motion. Here, we present characterization of swimming of onboard-powered autonomous robots inside cylindrical tubes. Robots consist of two links, head and tail, connected with a revolute joint. Rigid helical tails of the swimmer robots are made of steel wires with 12 different configurations of helical radius and pitch. From experiments forward linear velocity of robots and angular velocities of the links are measured, and compared with the mathematical model, which is based on the resistive force theory. Results indicate that the motion of the swimmer inside channels can be predicted by means of the resistive force theory reasonably well

Accelerating Aquatic Soft Robots with Elastic Instability Effects

Sinusoidal undulation has long been considered the most successful swimming pattern for fish and bionic aquatic robots [1]. However, a swimming pattern generated by the hair clip mechanism (HCM, part iii, Figure 1A) [2]~[5] may challenge this knowledge. HCM is an in-plane prestressed bi-stable mechanism that stores elastic energy and releases the stored energy quickly via its snap-through buckling. When used for fish robots, the HCM functions as the fish body and creates unique swimming patterns that we term HCM undulation. With the same energy consumption [3], HCM fish outperforms the traditionally designed soft fish with a two-fold increase in cruising speed. We reproduce this phenomenon in a single-link simulation with Aquarium [6]. HCM undulation generates an average propulsion of 16.7 N/m, 2-3 times larger than the reference undulation (6.78 N/m), sine pattern (5.34 N/m/s), and cambering sine pattern (6.36 N/m), and achieves an efficiency close to the sine pattern. These results can aid in developing fish robots and faster swimming patterns