Application of magnetorheological fluids for a miniature haptic button: Experimental evaluation

This study investigates a miniature haptic button actuated by magnetorheological fluids with the aim of conveying kinesthetic information or realistic button sensations to users for small electronic devices. To this end, a prototype haptic button that creates varying kinesthetic sensations was designed and constructed. The design focus was to maximize the resistive force generated by magnetorheological fluids in a given size by using multiple operating modes of the fluids. In order to evaluate the performance of the prototype, a test setup consisting of a microstage and a precision load cell was constructed. Using the setup, the resistive force of the prototype button was measured by changing the indented depth and the input current. The results show that the force rate (defined as the ratio of the difference between the maximum force and the minimum force to the maximum force) is over 72% for all indented depths (up to 1.5 mm). This change is sufficient to create various button sensations, indicating that the proposed haptic button can offer a range of resistive force change that can be conveyed to human operators.