There is a strong demand for the contactless transportation device for a hard disk and silicon wafer without contaminating and damaging them. To fulfill this requirements, A transportation device for them has been proposed. But the device needs many of costly displacement sensors positioned along the transportation interval and possesses a very complicated controller and driving scheme. To overcome those kinds of drawback, in this paper, we present a very simple and cost-effective transportation device which only consists of a linear guide, very simple electrostatic suspension system and driving circuit of stepping motor. The principle of stable suspension by relay feedback control, derivation of lateral restoring force, the design of transportation system are described, followed by the experimental system. Experimental results show that a 3.5-inch hard disk has been transported with a speed of approximately 20㎜/s while being suspended stably at a gap of 0.25㎜.
