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A novel bearingless disk motor for a possible application of implantable centrifugal artificial hearts is proposed in this paper. To reduce a motor height, C-shaped stator cores with radially expanded coil windings are employed. End windings are not located in the axial direction. The motor height and an outer diameter are designed to be 10mm and 70mm, respectively. Magnetic suspension characteristics of the bearingless disk motor are analyzed by using finite element method. The design consideration of a suspension winding configuration has been discussed especially on radial suspension force variations. A prototype machine is fabricated and tested. Experimental results have provided the feasibility of the design of the bearingless disk motor.Index Terms-Bearingless motor, magnetic bearing, magnetic levitation, artificial heart, blood pump.

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This paper presents a touch probe system with improved sensitivity and repeatability. In this probe, a tip ball is attached to the probe stylus through elastic bodies that enable the ball to be displaced in three directions. When the tip ball touches the workpiece, three fibre optic lever displacement sensors measure directly the ball's displacement and direction. Because the ball is located in sensitive directions of all of the sensors, this probe complies with Abbe's principle, which is a basis of precision measurement. Various performance tests have been performed using one-dimensional stages. The measurement resolution of the tip ball displacement was less than 12 nm in these experiments. Thus, the probe triggering level was set safely to 50 nm, taking into account the associated noise levels. The variation of the pretravel was less than 25 nm in all directions. The measurement force was approximately 0.6 mN in the horizontal direction and 4.5 mN in the vertical direction.

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