Development of a pulsed electromagnetic micro-actuator for 3D tactile displays

We propose an electromagnetic micro-actuator for tactile displays based on magnetization of the solenoid by a sharp current pulse. By applying DC to the solenoid, the force-current relation in a static configuration of the actuator is determined. An experiment to produce vibrating stimulation on human fingertip is presented using a single actuator unit. Four frequencies (10, 50, 100, and 150Hz) were used to test the perception limit of two volunteer subjects. The results indicated that the perception is not strongly dependent on frequency in the test range. The working frequency of the device was, therefore, limited to 50 Hz to allow the use of relative high charge storing capacitor and larger heat dissipation intervals. The actuator was then actuated as a function of its real-time position to "display" several virtual shapes. The results showed that five out of six simple geometries were perceived correctly.