Masatsugu Otsuki

When the lander carries a large amount of fuel, the landing on a celestial body becomes difficult and dangerous due to sloshing of fuel. Sloshing of fuel causes turbulence of attitude and overturning of the lander. In order to design a landing gear and attitude control system, landing simulation with a sloshing will be required. The mechanical sloshing model that takes the place of experiment and computational fluid dynamics is required for the landing simulator. This paper describes the modelling of mechanical concentrated-constant sloshing models for a landing simulator and the result of numerical simulations of landing on a small body celestial bodies.

Understanding the interaction between granular materials on surface of a small body and a spacecraft is the key issue to design equipments of the spacecraft utilized in a future planetary exploration. Aiming to realize a safe long-term stay on the small body, this paper presents the experimental results that acquired the basic data about the interaction through the drop tower test.

<p>This paper describes the design of the hopping rover for the moon or Mars surface exploration. Hopping rover is one of solution for locomotion on loose and rocky terrain on the moon and planetary surface. The hopping rover can jump over an obstacles. Since the height of hopping is equal to the height which the rover can get over, the traversability of rover becomes higher than that of the small wheeled rover. In this paper, we describe the whole design of the hopping rover, design of hopping mechanism, simulator with the estimation of terrain force, action strategy, and the scientific missions.</p>

<p>Planetary surface mobility is one of the key technologies for future deep space missions. However conventional rovers are so big and expensive. To enhance robotic surface exploration missions, small, light-weight explorers are required. Therefore this paper proposes a new hopping locomotion system for small planetary rover using shape-memory-alloy(SMA) actuator. The proposed mechanism is analysed based on SMA constitutive mathematical model. Simulation results show that proposed mechanism has the capability of horizontally 2.5 m jump under the 1/6 gravity environment.</p>

This study discusses an airbag system as a landing gear of a spacecraft for a planetary exploration. The inflated airbag has the capability to attenuate impact acceleration at the instant of landing and submergence into regolith that covers a planetary surface. Crash tests in this paper verify the attenuation performance of the airbag and specify an issue.

For planetary exploration, small robots of just a few kilograms installed in the main spacecraft have a lot of advantages. In order to move on the surface of a &ldquo;low gravity&rdquo; object, like the Moon by a small robot, there are several options of locomotion, such as jumping, wheels, and legs. Jumping locomotion has capable of moving a long distance by one action and the number of actuators required for jumping capability is very small. In addition, it can travel a longer distance on a planet or satellite which has a gravity lower than the Earth. For instance, it can jump 6 times longer on the Moon than on the Earth. To realize jumping locomotion for small robots in a low gravity environment, authors proposed a new jumping locomotion method which consists of one jumping mechanism and one wheel for attitude and direction change, as well as they are now studying the mechanism which moves in a space environment (vacuum, high radiation). In this paper, the jumping mechanism is mainly described. The design of the jumping mechanism, test results on granular media are presented.

The authors have installed a tiny rover payload &ldquo;MINERVA-II&rdquo; into Hayabusa2 spacecraft which was launched in 2014. The payload consisted of three rovers installed in two containers. Two of them packed together in one container were the responsibilities of the authors. The other one in the secondary container came from the domestic university members. We developed a new rover deployment mechanism ejected from the containers. The rovers and the cover of the container were released by one action. But the cover headed for different direction of the one from rovers, so as to prevent the combination of them. The deployment mechanism was evaluated under the microgravity environment using a drop tower. This paper describes the deployment mechanism as well as the results of the microgravity experiments.