Lower Gravity Demonstratable Testbed for Space Robot Experiments

In developing mobile robots for exploration on the planetary surface, it is crucial to evaluate the robot's performance, demonstrating the harsh environment in which the robot will actually be deployed. Repeatable experiments in a controlled testing environment that can reproduce various terrain and gravitational conditions are essential. This paper presents the development of a minimal and space-saving indoor testbed, which can simulate steep slopes, uneven terrain, and lower gravity, employing a three-dimensional target tracking mechanism (active xy and passive z) with a counterweight.Comment: 2 pages, 3 figures, paper accepted for the SII 2024 (IEEE/SICE International Symposium on System Integration) (Updated references formatting

Mobility Analysis of Hopping and Tumbling Motion in Microgravity

This paper presents the analyses of the tumbling and hopping mobility of a novel moving mechanism on small celestial bodies in microgravity. The robot consists of an inner motor with a flywheel and eight elastic spikes connected to the perimeter of the robot. The tumbling and hopping motion of the robot can be switched by controlling the torque of the motor. Hence, the robot can traverse a large region with high moving accuracy. In this paper, we conduct several numerical simulations to analyze the characteristics of the mobility by assigning various values of elastic and damping coefficient of spikes, and the torque of the motor. The results are useful to construct the feasible motion planning for real missions.International Symposium on Artificial Intelligence, Robotics and Automation in Space (i-SAIRAS 2020), October 19-23, 2021, Los Angles, CA, USA（新型コロナ感染拡大に伴い、オンライン開催に変更

Tumbling and Hopping Locomotion Control for a Minor Body Exploration Robot

This paper presents the modeling and analysis of a novel moving mechanism "tumbling" for asteroid exploration. The system actuation is provided by an internal motor and torque wheel; elastic spring-mounted spikes are attached to the perimeter of a circular-shaped robot, protruding normal to the surface and distributed uniformly. Compared with the conventional motion mechanisms, this simple layout enhances the capability of the robot to traverse a diverse microgravity environment. Technical challenges involved in conventional moving mechanisms, such as uncertainty of moving direction and inability to traverse uneven asteroid surfaces, can now be solved. A tumbling locomotion approach demonstrates two beneficial characteristics in this environment. First, tumbling locomotion maintains contact between the rover spikes and the ground. This enables the robot to continually apply control adjustments to realize precise and controlled motion. Second, owing to the nature of the mechanical interaction of the spikes and potential uneven surface protrusions, the robot can traverse uneven surfaces. In this paper, we present the dynamics modeling of the robot and analyze the motion of the robot experimentally and via numerical simulations. The results of this study help establish a moving strategy to approach the desired locations on asteroid surfaces.2020 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), October 25, 2020 - January 24, 2021, Las Vegas, NV, USA （新型コロナ感染拡大に伴い、現地開催中止

Involvement of SIK3 in Glucose and Lipid Homeostasis in Mice

Salt-inducible kinase 3 (SIK3), an AMP-activated protein kinase-related kinase, is induced in the murine liver after the consumption of a diet rich in fat, sucrose, and cholesterol. To examine whether SIK3 can modulate glucose and lipid metabolism in the liver, we analyzed phenotypes of SIK3-deficent mice. Sik3−/− mice have a malnourished the phenotype (i.e., lipodystrophy, hypolipidemia, hypoglycemia, and hyper-insulin sensitivity) accompanied by cholestasis and cholelithiasis. The hypoglycemic and hyper-insulin-sensitive phenotypes may be due to reduced energy storage, which is represented by the low expression levels of mRNA for components of the fatty acid synthesis pathways in the liver. The biliary disorders in Sik3−/− mice are associated with the dysregulation of gene expression programs that respond to nutritional stresses and are probably regulated by nuclear receptors. Retinoic acid plays a role in cholesterol and bile acid homeostasis, wheras ALDH1a which produces retinoic acid, is expressed at low levels in Sik3−/− mice. Lipid metabolism disorders in Sik3−/− mice are ameliorated by the treatment with 9-cis-retinoic acid. In conclusion, SIK3 is a novel energy regulator that modulates cholesterol and bile acid metabolism by coupling with retinoid metabolism, and may alter the size of energy storage in mice

DEM Analysis and Evaluation of Hopping Motion on a Sandy Surface in Microgravity

Hopping mobility is effective for exploration robots present on small celestial bodies including asteroids and comets and their surfaces are covered in certain places with granular materials such as fine grain sand. However, existing studies do not address hopping mobility on the aforementioned types of granular materials in detail. Therefore, it is necessary to analyze hopping motion on sandy surface for future missions. This study presents a parametric analysis of the hopping motion on granular materials based on a discrete element method (DEM) simulation. In particular, the DEM allows for the numerical simulation of the dynamic behaviors of numerous fine particles. The DEM defines a sand particle as a simple sphere and computes mechanical interaction between each particle which follows some simple laws of dynamics. To analyze the hopping motion, we focus on two characteristics of the hopping motion: the initial hop velocity and hop angle of the robot. In DEM simulations, we change the friction and rolling friction coefficient of the sand particles, the acceleration of gravity and the angular velocity of the robot. We perform a simplified analysis and assume that the terrain surface in DEM simulation is smooth and flat and that the robot exhibits a cubic shape. Based on the research results, we qualitatively evaluate the exploration robot\u27s motion on a sandy surface by DEM analysis when compared with its motion on a rigid surface.International Symposium on Space Technology and Science (32nd ISTS), June 15-21, 2019, Fukui, Japa

イメージスキャン画像分割アーキテクチャのLSI設計

画像認識処理技術,特にリアルタイムでの動物体検出には,膨大な視覚情報を処理する必要がある.画像分割処理は画像中に存在する物体を抽出する処理で,オブジェクトベースの画像認識などには欠かせない前処理である.これまでに我々は領域成長に基づくイメージスキャン画像分割アーキテクチャを提案した.同アーキテクチャは処理回路 (以下ISE) のサイズとメモリの構成を変えることで,アプリケーションに応じて処理速度と処理回路サイズの最適化が可能な柔軟性を有する.本研究では,同アーキテクチャのボトルネックとなるリーダセル検索を非同期化を行い,180 nm CMOS プロセスでASIC設計を行った