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Magnetic Actuator for a Capsule Endoscope Navigation System
Atsushi Chiba,Masahiko Sendoh,Kazushi Ishiyama,Ken Ichi Arai,Hironao Kawano,Akio Uchiyama,Hironobu Takizawa 한국자기학회 2007 Journal of Magnetics Vol.12 No.2
The authors propose a magnetic actuator for use as a navigation system for capsule endoscopes. The actuator is composed of a capsule dummy, a permanent magnet inside the capsule, and an external spiral structure. The device rotates and propels wirelessly when exposed to an external rotational magnetic field. In this study we measured the effect of the spiral shape on the velocity and thrust force properties. According to our experimental results, the actuator obtained a maximum velocity and thrust force when the spiral angle was set at 45 degrees, the number of spirals was set at 4, and the spiral-height was set at 1-㎜f. We also conducted a motion test in the large intestine of a pig placed on a 30 degrees slope. The actuator passed through a 700 ㎜ length of the intestine in about 300 s. The device also managed to travel up and down the 30 degrees slope with no difficulty whatsoever. Our results demonstrate the great potential of this actuator for use as a navigation system for capsule endoscopes.
Analytic Singularity Analysis of a 4-DOF Parallel Robot Based on Jacobian Deficiencies
최희병,Atsushi Konno,Masaru Uchiyama 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.2
In this paper, analytic singularity analysis of a 4-DOF parallel robot H4 is addressed. Since a parallel manipulator consisting of several serial chains has complex singularities in the workspace, the determination of singular configurations is very important in design, trajectory planning, and control. The classical method to determine singular configurations is to find the determinant of the Jacobian matrix. However, the Jacobian matrix of a parallel manipulator is complex in general and thus it is not easy to find the determinant of the Jacobian matrix. Therefore, we focus on the analytic singularity analysis of a 4-DOF parallel robot H4 using Jacobian deficiencies. A subset of the whole singularities and the intuitively predictable ones are only derived using Jacobian matrix deficiency. Three type sin-gularities, i.e., overmobility, undermobility and combined singularities, have been presented.
Closed-Form Forward Kinematics Solutions of a 4-DOF Parallel Robot
최희병,Masaru Uchiyama,Atsushi Konno 제어·로봇·시스템학회 2009 International Journal of Control, Automation, and Vol.7 No.5
It is well known that the forward kinematics of parallel robots is a very difficult problem. Closed-form forward kinematics solutions have been reported only to a few special classes of parallel robots. This paper presents closed-form forward kinematics solutions of a 4-DOF parallel robot H4. A 16th order polynomial in a single variable is derived to solve the forward kinematics of the H4. The 16 roots of the polynomial lead to at most 16 different forward kinematics solutions. A numerical verification is also presented.
A NOTE ON *-PARANORMAL OPERATORS AND RELATED CLASSES OF OPERATORS
Kotaro Tanahashi,Atsushi Uchiyama 대한수학회 2014 대한수학회보 Vol.51 No.2
We shall show that the Riesz idempotent E of every ∗- paranormal operator T on a complex Hilbert space H with respect to each isolated point of its spectrum (T) is self-adjoint and satisfies EH = ker(T − ) = ker(T − )∗. Moreover, Weyl’s theorem holds for ∗-paranormal operators and more general for operators T satisfying the norm condition ∥Tx∥n ≤ ∥Tnx∥kx∥n−1 for all x ∈ H. Finally, for this more general class of operators we find a sufficient condition such that EH = ker(T − ) = ker(T − )∗ holds. We shall show that the Riesz idempotent E of every ∗- paranormal operator T on a complex Hilbert space H with respect to each isolated point of its spectrum (T) is self-adjoint and satisfies EH = ker(T − ) = ker(T − )∗. Moreover, Weyl’s theorem holds for ∗-paranormal operators and more general for operators T satisfying the norm condition ∥Tx∥n ≤ ∥Tnx∥∥x∥n−1 for all x ∈ H. Finally, for this more general class of operators we find a sufficient condition such that EH = ker(T − ) = ker(T − )∗ holds.
A NOTE ON ∗-PARANORMAL OPERATORS AND RELATED CLASSES OF OPERATORS
Tanahashi, Kotoro,Uchiyama, Atsushi Korean Mathematical Society 2014 대한수학회보 Vol.51 No.2
We shall show that the Riesz idempotent $E_{\lambda}$ of every *-paranormal operator T on a complex Hilbert space H with respect to each isolated point ${\lambda}$ of its spectrum ${\sigma}(T)$ is self-adjoint and satisfies $E_{\lambda}\mathcal{H}=ker(T-{\lambda})= ker(T-{\lambda})^*$. Moreover, Weyl's theorem holds for *-paranormal operators and more general for operators T satisfying the norm condition $||Tx||^n{\leq}||T^nx||\,||x||^{n-1}$ for all $x{\in}\mathcal{H}$. Finally, for this more general class of operators we find a sufficient condition such that $E_{\lambda}\mathcal{H}=ker(T-{\lambda})= ker(T-{\lambda})^*$ holds.
Fuglede-Putnam theorem for $p$-hyponormal or class ${\mathcal Y}$
Salah Mecheri,Kotaro Tanahashi,Atsushi Uchiyama 대한수학회 2006 대한수학회보 Vol.43 No.4
We say operatorsA;Bon Hilbert space satisfy Fuglede-Putnam theorem ifAX = XB for someX implies AX = XB.We show that if either (1)A is p-hyponormal and Bis a classYoperator or (2)A is a classY operator and Bis p-hyponormal,then A;B satisfy Fuglede-Putnam theorem.
FUGLEDE-PUTNAM THEOREM FOR p-HYPONORMAL OR CLASS y OPERATORS
Mecheri, Salah,Tanahashi, Kotaro,Uchiyama, Atsushi Korean Mathematical Society 2006 대한수학회보 Vol.43 No.4
We say operators A, B on Hilbert space satisfy Fuglede-Putnam theorem if AX = X B for some X implies $A^*X=XB^*$. We show that if either (1) A is p-hyponormal and $B^*$ is a class y operator or (2) A is a class y operator and $B^*$ is p-hyponormal, then A, B satisfy Fuglede-Putnam theorem.