Masatsugu Otsuki

Balloon Symposium 2016 (November 1-2, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan

When a spacecraft lands, a large shock load can lead to undesirable responses such as rebound and tripping. The authors previously discussed the problem of controlling these shock responses using momentum exchange impact dampers (MEIDs). MEIDs are classified by momentum exchange directions as follows: Upper-MEID (U-MEID) that launches the damper mass upward, Lower-MEID (L-MEID) that drops the damper mass downward, and Generalized-MEID (G-MEID) consisting of U-MEID and L-MEID, and G-MEID-A (G-MEID-Advanced) that has both upward and downward launching effect on single damper mass, by introducing initial tension to the MEID spring. However, studies of these MEIDs are mainly based on one-dimensional motion. Two-dimensional motion analyses have been done for only U-MEID. This research aims to derive the generalized MEID design methodology for two-dimensional motions. G-MEID-A, that is the most effective one for shock response control in previous MEIDs in the one-dimensional motion, are applied to multi-legged landing gear system. There are two damper masses, one is released to control spacecraft attitude, and the other is released to reduce landing shock. Their parameter design and optimal release timing are discussed in this paper. The effectiveness and robustness against landing slope angle variation of the proposed design methodology are verified by simulations.

<p>In recent years, the eyes of the world has been upon a space exploitation mission with a micro robotic science probe such as MINERVA, MINERVA2 and son on, which mostly have been used under micro gravity environment. However we can find enough room in a launching vehicle and have many chances launching micro robots for large gravity environment, and they are expected for a lot of scientific results. In this paper, we discuss a micro rover for heavenly bodies, and propose some designs of one wheeled hopping rovers under a severe conditions for launching size and weight. Its basic behavior flow is also discussed with some technical subjects, and finally we focus on direction recognition with illuminance dependence of the sun light. According to this estimation of sun direction, the rover will be able to navigate to a goal point or area by itself. Here, we discuss a method to estimate the direction of the sun with some photo diodes, and also mention about arrangements and minimum number of diodes.</p>

<p>This paper presents a novel method of monocular visual odometry for a hopping robot, or a hopper. Firstly, a monocular scheme of visual odometry is applied to estimate the relative poses between three frames up to a scale factor. The scale ambiguity is resolved with the parabolic motion constraints of hopping robots. The whole trajectory can be recovered by estimating motion parameters including the initial velocity and angle. The proposed method is validated with synthetic data, and proved that it can accurately estimate the hopping motion with the absolute scale using only a single monocular camera.</p>

<p>In recent years, planetary surface exploration missions by rovers have been actively performed. Rovers are required to recognize the surrounding environment autonomously for an efficient and safe exploration. Above all, terrain slope estimation is one of the essential techniques, which is conventionally performed with stereo cameras or shape-from-shading techniques. However, those schemes have problems such as the degraded accuracy in low-textured terrain and the heavy computational cost. Therefore, this paper proposes a new method that uses the difference of surface temperatures between at and slanted surfaces. It is known that the difference of solar radiation generates the gap in surface temperatures, which can be remotely detected with an infrared camera. The proposed method estimates terrain tilt angles using the energy balance equation and a single thermal image from the infrared camera. The method is validated with a field experiment in Izu-Oshima island. The developed thermal-based technique potentially increases the applicability to various terrain types regardless of the terrain appearance.</p>

16th Space Science Symposium (January 6-7, 2016. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan

大気球シンポジウム 平成27年度（2015年11月5-6日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県著者人数: 16名ほか資料番号: SA6000044002レポート番号: isas15-sbs-002

This paper describes the control method of the semi-active controlled landing gear system for the lunar and planetary lander. The purpose of this paper is to achieve touchdown on uneven terrain without overturning. Damping force control on each landing gear suppress attitude disturbance of lander main body and prevent from its overturning. The control rule of the landing gear damping coefficient of each landing gear for the three-dimensional lander model is shown and it validated in the three-dimensional numerical simulation model. Touchdown simulation executed on rough terrain which reproduced natural terrestrial surface. Especially, touchdown on the incline and touchdown with a lateral residual velocity are tested. The result of simulation indicates that the proposed control rule for the semi-active landing gear is effective to prevent overturning.

Surface mobility on planetary bodies has enabled nearly two decades of scientifically-rich exploration of the red planet, however not without its challenges. Future exploration will likely demand enhanced mobility to access more challenging terrain. In this paper, we apply resistive force theory (RFT) to a general grouser geometry model, and present simulation results that show the impact of several parameters on draw-bar pull. This work represents initial steps toward optimizing grouser geometry to maximize draw-bar pull, while maintaining ability to traverse rocks of certain geometries and minimizing energy usage per traverse distance. These criteria are of particular importance in power-constrained planetary rovers.

This paper presents that the skyline matching algorithm with considering camera tilt. Skyline matching is the method that estimating position and attitude by comparing two skylines. One skyline is simulated one from a digital elevation model (DEM). The other one is gotten from camera images taking around view. We conducted field experiments in Oshima Island. As a result, we conclude that considering camera tilt has a significant influence.

15th Space Science Symposium (January 6-7, 2015. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan