Response time of magnetorheological fluid–based haptic device

Abstract

Haptics is a tactile feedback technology that recreates the sense of touch to the user by applying forces, vibrations, or motions. Haptic devices should have a high performance in their output characteristics, for example, low friction in off-state, constant force with constant input, and quick response with dynamic input, in order to generate a sufficient sense of touch to human skin. We have focused on rapid response of magnetorheological fluid and decided to use it as the working material of the haptic device. There are several types of magnetorheological fluids available, and the effects of the different types of magnetorheological fluids on the response time of the haptic device have not yet been reported. The objective of this study is to experimentally investigate the response time of a magnetorheological fluid–based haptic device with two different types of magnetorheological fluids. We originally developed a single-disc type magnetorheological fluid–based haptic device, and its response time was investigated with two types of magnetorheological fluids. We set three experimental conditions with regard to the fluid gap and rotational velocity. We modeled the haptic devices as a classic first-order lag system, and the time constant of this system was assumed to be representative of the response time of the haptic device. According to the results, the response times of a sample tend to be smaller with the narrow gap (0.1 mm), whereas those of the other tend to be smaller with the large gap (0.5 mm). In addition, the response time is non-dimensioned and investigated with Mason number.