In this paper, we describe the development of an orthogonal microrobot for accurate microscopic operations. To conduct the microscopic operation, a simple locomotion mechanism composed of one piezoelectric actuator and two U-shaped electromagnets is proposed. The orthogonal microrobot can move precisely in one-axis with the manner of an inchworm. We use permanent magnets so that this robot can fix itself on a steel surface when no voltage is applied. To provide XY orthogonal positioning, we connect one microrobot to another microrobot orthogonally. To realize cell processing, we arrange the three two-axial orthogonal microrobots on an inverted microscope. We load a simple micropump on right and left robots to hold biological samples such as an egg cell and to inject reagent solutions into biological samples. Finally, we arrange another microrobot between the other two microrobots to position samples. The whole cell processing device is very small, so we can easily set up the whole device to microprocessing instruments. In experiments, orthogonal microrobots succeeded in holding an egg cell with a diameter of 100 μm and sticking the pipette with a diameter of 5 μm into the egg cell under a specific GUI control system with a visual feedback function.
For Above Deck Equipment (ADE) on a ship, it is necessary to perform experimental modal analysis (EMA) by base excitation. Existing EMA tools are designed to perform curve-fitting on the frequency response function of displacement or acceleration at measuring point to an excitation force. However, in case of experiment by base excitation, transmissibility of acceleration, that is, the ratio of accelerations between measuring point and base is to be used for modal analysis. A method, which makes modal analysis for base excitation possible by performing curve-fitting on the transmissibility of acceleration using existing EMA tools, is proposed in this paper . First, the relation of transmissibility of acceleration using modal parameters in case of base excitation is derived. Based on the relation, a new method for modal analysis is given and its feasibility for one D. O. F. system is shown by numerical calculation. Finally, the method is applied to the modal analysis of an ADE, and its effectiveness is shown by comparing experimental results with simulation results using the modal parameters obtained by the method.
This paper presents a controller structure for a fast and precise fine positioner which can be attached to the end-effector of a classical industrial robot for assembly tasks. The overall control system consists of three elements: a position loop feedback controller, a feedforward controller, and a disturbance observer for the position loop. A useful method for compensating for the asymmetry and non-linearities of the piezoelectric based system is used as the first step in the design process. The robust feedback controller based on the disturbance observer compensates for external disturbances mainly from the coarse positioner. Precise tracking is achieved by the feedforward controller. Experimental results are presented to demonstrate performance improvement obtained by each element in the proposed robust structure.
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