Recently, there have been many researches about Autonomous Underwater Vehicle (AUV) which is imitated motion of aquatic lives. We have been developed an Eel-like robot that swims by anguilliform swimming on the water. In this paper, to add the function of diving for Eel-like robot, we developed 2DOF neck mechanism. In the experiment, it observed that the Eel-like robot could dive while swimming with bending neck down. The results shows, diving speed could control by change the angle of neck.
The propulsion method based on the aquatic life has many advantages as compared with the screw propeller. We have been developed Eel-like swimming robots of prototype 1 and prototype 2. The efficiency of swimming behavior depends on the shape of the robot in the water. In this paper we report the effect of changing the head shape, entire length of Eel-like swimming robot, and the number of the progressive wave. The miniaturized head reduced fluid resistance and improved swimming speed of an Eel-like robot. Prototype 2 robot swims underwater completely and on the surface of the water. In the case of swimming by serpentine movement like snakes and eels, furthermore, the swimming efficiency is affected by the shape of the cross section of the body. So we changed it into circular and rectangular cross section, and investigated the effect to the swimming form and the swimming speed. The number of the progressive wave has as big influence on the swimming performances as robot shape.
This report shows an eel-like robot having eight joint units which consist of actuator joint servomotors and phosphor bronze plate for the elastic joints. The total body length and mass are 860mm and 2.8kg respectively. The robot was contained a microcomputer and batteries within the head. In addition, a computer simulation is carried out an analytical model and dynamic equations to compare the experimental results. In the experiment and simulation, the eel-like robot turned steady for turning of radius 0.4m to 0.8m. Then, the velocity loss was superior at 45% compared with a general ship. In addition, the robot turn suddenly by stopping undulation at constant time and got turning angle about 90deg to 170deg. The time for which the robot needed to turn was superior to that of a general ship. The eel-like robot was able to brake by two methods in the experiment. Braking distances were 0.53m and 0.11m, respectively.
This paper investigates an optimal pulse-width-modulated (PWM) control of distributed parameter systems by the extension of Kirk's method. The PWM control is assumed to operate on a boundary of a state domain. Using a variational approach, necessary conditions for optimality are obtained.A solution which satisfies these conditions can be obtained by the gradient method and a numerical example is shown to illustrate the procedure to obtain the solution.The merit of this approach lies in its applicability to a comparatively wide range of plant dynamics and types of performance indices.
The frequency patterns for the different kinds of dumpy mutations induced by X-rays in successive stages of spermatogenesis were studied by making two-day brood changes with 3 females per male per brood. With this mating procedure, mature sperms are probably sampled in brood A, late spermatids in brood B, early spermatids and presumably late spermatocytes in brood C, early spermatocytes in brood D.The experimental results obtained indicate that (i) the over-all frequencies of recovered complete dumpy mutations are relatively similar in broods A and B, begin to increase gradually in brood C, reach its highest level in brood D and decline sharply in brood E; (ii) the frequency patterns for the (ol, lv) and (ov, olv) exceptions over the five sampling broods are practically similar to that observed in the total dumpy mutations; (iii) no such differences in brood-mutation pattern are found, however, with respect to the yield of the (o, v) types; (iv) the over-all frequencies of recovered fractional dumpy mutations appear to be relatively steady from stage to stage, although the majority of the fractionals are of the o and v types.These findings indicate that the different kinds of dumpy exceptions may be differentially affected under different germ cell stages of maturity. Probably, this might represent a difference between point mutations and breakage events.
