This paper extends a stability theory of 2-D object grasp to cope with 3-dimensional(3-D) object grasp by a pair of multi-joint robot fingers with hemi-spheric ends. It shows that secure grasp of a 3-D object with parallel surfaces in a dynamic sense can be realized in a blind manner like human grasp an object by a pair of thumb and index finger while their eyes closed. Rolling contacts are modeled as Pfaffian constraints that can not be integrated into holonomic constraints but exert tangential constraint forces on the object surfaces. A noteworthy difference of modeling of 3-D object grasping from the 2-D case is that the instantaneous axis of rotation of the object dynamics of the overall fingers-object system are subject to non-holonomic constraints regarding a 3-D orthogonal matrix consisting of three mutually orthogonal unit-vectors fixed at the object. Lagrange's equation of motion of the overall system can be derived from the variational principle without violating the causality that governs the nonholonomic constraints. Then, a simple control signal constructed on the basis of fingers-thumb opposable forces together with an object-mass estimator is shown to accomplish stable grasp in a dynamic sense without using object information or external sensing. The closed-loop dynamics can be regarded as Lagrange's equation of motion with an artificial potential function that attains its minimum at some equilibrium state of force/torque balance. A mathematical proof of stability and asymptotic stability on a constraint manifold of the closed-loop dynamics under the nonholonomic constraints is presented.
This paper presents a nonlinear sliding mode control and its applications to swing-up and stabilization of a Furuta pendulum. The nonlinear sliding mode is computed by the State Dependent Riccati Equation. The approach is based on the Lyapunov function and the stability is assured under the given condition. The validity of the proposed design method is studied through the simulation of swing-up/stabilization control.
This paper mentions circumstance of mechatronics that sustain our human society, and introduces HAM(Human Adaptive Mechatronics)-project as one of research projects to create new human-machine system. The key point of HAM is skill, and analysis of skill and establishment of assist method to enhance total performance of human-machine system are main research concerns. As study of skill is an elucidation of human itself, analyses of human higher function are significant. In this paper, after surveying researches of human brain functions, an experimental analysis of human characteristic in machine operation is shown as one example of our research activities. We used hovercraft simulator as verification system including observation, voluntary motion control and machine operation that are needed to general machine operation. Process and factors to become skilled were investigated by identification of human control characteristics with measurement of the operator's line-of sight. It was confirmed that early switching of sub-controllers / reference signals in human and enhancement of space perception are significant.
The paper is concerned with a fully adaptive semi-active control scheme which can deal with uncertainties in both models of MR damper and suspension mechanism. The proposed approach consists of two adaptive control algorithms. The first is an adaptive inverse control for compensating the nonlinear hysteresis dynamics of the MR damper, which can be realized by identifying a forward model of MR damper and then calculating the input voltage to generate a reference damping force. It can also be realized directly by updating an inverse model of MR damper without identification of the forward model, which then works as an adaptive inverse controller. The other is an adaptive reference feedback control which gives the desired damping force to match the seat dynamics to a specified reference dynamics even in the presence of uncertainties in the suspension structure. The stability of the total system including the two adaptation algorithms is discussed and its stability condition is explored. Validity of the proposed algorithm is also examined in simulation studies.
This paper describes a strategy of optimal sensing action selection for recognition of the observed object among those registered in the image data base. This strategy is built from an information theoretic point of view. The goal is to reduce the number and effort of the recognition steps to reach the final decision of the recognition. We have chosen an information theoretic framework, motivated by the fact that sensored image data is not noiseless or ideal, nor can the effect of a certain action be completely determined in advance. We present an actual strategy of the recognition process, and then, the results of the feasibility study by experiments.
We report nanomanipulation and nanoassembly through nanorobotic manipulation inside electron microscopes. A hybrid nanorobotic manipulation system, which is integrated with a nanorobotic manipulator inside a transmission electron microscope (TEM) and nanorobotic manipulators inside a scanning electron microscope (SEM), is used. The elasticity of a multi-walled CNT (MWNT) is measured inside a TEM. The telescoping MWNT is fabricated by peeling off outer layers through destructive fabrication process. The electrostatic actuation of telescoping MWNT is directly observed by a TEM. A cutting technique for CNTs assisted by the presence of oxygen gas is also presented. The cutting procedure was conducted in less than 1 minute using a low-energy electron beam inside a scanning electron microscope. A bending technique of a CNT assisted by the presence of oxygen gas is also applied for the 3-D fabrication of nanosturucture. We expect that these techniques will be applied for the rapid prototyping nanoassembly of various CNT nanodevices. For the nano-biological applications, environmental-SEM (E-SEM) nanomanipulation system is also presented with the direct observation of the hydroscopic samples with non-drying treatment.
This paper gives a comprehensive account on a class of distributed parameter systems, whose impulse response is called pseudorational. This notion was introduced by the author in 1980's, and is particularly amenable for the study of systems with bounded-time memory. We emphasize algebraic structures induced by this class of systems. Some recent results on coprimeness issues and H∞ control are discussed and illustrated.
This paper provides new expressions of H2 control performance limits achievable by feedback for SISO continuous-time systems. The result for the regulation problem is expressed in a simple manner in terms of two sums of roots obtained from the plant and the associated polynomial spectral factorization. We show that it can connect the two existing solutions, namely the Riccati solution and the analytical expression with an integral form. The similar result for the tracking problem is also derived using the reciprocal transform. Finally parametric optimization making use of the derived expression by means of symbolic computation is demonstrated to confirm the validity of the sum of roots characterization.
This paper proposes a new control algorithm for a class of nonholonomic systems using ON/OFF-type discrete-valued control inputs. Our approach is based on second-order approximation of the principle of holonomy and its iteration with parameter updating, which is intended to be tolerant of severe inaccuracy of the control inputs. The proposed method is applied to attitude control of 2D and 3D free-flying robots and a wheeled mobile robot to demonstrate its effectiveness. Simulation results show its robustness against the model uncertainty and unmodeled dynamics such as non-Chaplygin type structure.
In this research, we have developed a dance partner robot, which has been developed as a platform for realizing the effective human-robot coordination with physical interaction. The robot could estimate the next dance step intended by a human and dance the step with the human. This paper introduce the robot referred to as PBDR (Partner Ballroom Dance Robot), which has performed graceful dancing with the human in EXPO 2005, Aichi, Japan.