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Simultaneous Online Estimation of Lander’s Motion and Terrain’s 3D Shape Utilizing Imaging Sensors
Koki Fujita 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
This paper proposes a novel estimation technique to simultaneously identify both lander's motion and 3D shape of planetary terrain utilizing two types of imaging sensors. The proposed scheme is realized by utilizing camera and 2D scanning range sensor in a mutually complementary manner. The motion estimation algorithm in the scheme is derived from a state-space model with the lander's 6DOF velocities and the concept of Extended Kalman Filter (EKF). The observation equation for the state-space model is based on a relationship between the lander's motion and the scene points' optical flows in image frames, which is called ‘Image Jacobian’. Although the above estimation algorithm needs the depth data of some scene points selected in the image frames, they are not necessarily measured from the range images because of the range sensor’s low scan rate. Thus, another online estimation algorithm for the 3D locations of the selected scene points is preliminarily applied. On the other hand, DEM for all the scene points in the image frame is recovered every sampling time by the approach similar to the previously mentioned online estimation algorithm. Finally, to demonstrate the effectiveness of the proposed scheme, a series of numerical simulations are conducted.
Autonomous Identification of Debris’ Impact Craters Utilizing Range Image Sequence
Koki Fujita 제어로봇시스템학회 2009 제어로봇시스템학회 국제학술대회 논문집 Vol.2009 No.8
In this study, a new approach to autonomously detecting areal distribution of the small debris’ impact craters on the surface of spacecraft is proposed. The proposed method is implemented by utilizing a series of the range images captured with 2D scanning range sensor in a stationary motion. In order to precisely extract the spherical pitted areas on the planar surfaces, some invariant parameters with 3D curvatures are utilized, and the range sensor’s motion parameters are estimated from the flow data appearing in the range image sequence. The validity of the proposed method is checked through some fundamental experiments by using synthetic and real range image sequences.
Ransika De Alwis,Koki Fujita,Tatsuya Ashitani,Ken’ichi Kuroda 한국식물생명공학회 2009 Plant biotechnology reports Vol.3 No.1
Cultured Cupressus lusitanica cells induced by various stresses are thought to produce different complexes of defense chemicals to optimize defense. To compare the induced products of two stimulations, we investigated the emission of monoterpenes, biosynthesis of b-thujaplicin, and accumulation of lignin in mechanically stressed and fungal elicited cultured C. lusitanica cells. Both mechanical stress and fungal elicitor caused emission of qualitatively similar monoterpene blends indicating de novo biosynthesis of these compounds after stimulation, while mechanical stress alone is sufficient to induce fungal elicitor-related monoterpene emission. Sabinene and limonene were the dominant compounds over the time course in both volatile blends. Although the emitted volatile blends were qualitatively similar, the time course and the relative ratios of the constituents of the volatile blends differed with the type of stimulation. While fungal elicited cells produced significant amounts of b-thujaplicin over the 5-day time course, no b-thujaplicin was observed in the mechanically stressed cells. The production of b-thujaplicin was the main dissimilarity of the induced products of these two treatments, suggesting that synthesis of b-thujaplicin is not a general response to all types of stresses, but is a specific response and serves as a strong toxic compound against already invaded fungus. Significantly higher amounts of lignin accumulations were observed in the fungal elicited and mechanically stressed cells on the 5th day after induction. Based on these results, we suggest the composition of induced products was dependent on the method of stimulation. Cultured Cupressus lusitanica cells induced by various stresses are thought to produce different complexes of defense chemicals to optimize defense. To compare the induced products of two stimulations, we investigated the emission of monoterpenes, biosynthesis of b-thujaplicin, and accumulation of lignin in mechanically stressed and fungal elicited cultured C. lusitanica cells. Both mechanical stress and fungal elicitor caused emission of qualitatively similar monoterpene blends indicating de novo biosynthesis of these compounds after stimulation, while mechanical stress alone is sufficient to induce fungal elicitor-related monoterpene emission. Sabinene and limonene were the dominant compounds over the time course in both volatile blends. Although the emitted volatile blends were qualitatively similar, the time course and the relative ratios of the constituents of the volatile blends differed with the type of stimulation. While fungal elicited cells produced significant amounts of b-thujaplicin over the 5-day time course, no b-thujaplicin was observed in the mechanically stressed cells. The production of b-thujaplicin was the main dissimilarity of the induced products of these two treatments, suggesting that synthesis of b-thujaplicin is not a general response to all types of stresses, but is a specific response and serves as a strong toxic compound against already invaded fungus. Significantly higher amounts of lignin accumulations were observed in the fungal elicited and mechanically stressed cells on the 5th day after induction. Based on these results, we suggest the composition of induced products was dependent on the method of stimulation.