Tactile sensation is one type of valuable feedback in evaluating a product. Conventionally, sensory evaluation is used to get direct subjective responses from the consumers, in order to improve the product’s quality. However, this method is a time-consuming and costly process. Therefore, this paper proposes a novel tactile evaluation system that can give tactile feedback from a sensor’s output. The main concept of this system is hierarchically layering the tactile sensation, which is inspired by the flow of human perception. The tactile sensation is classified from low-order of tactile sensation (LTS) to high-order of tactile sensation (HTS), and also to preference. Here, LTS will be correlated with physical measures. Furthermore, the physical measures that are used to correlate with LTS are selected based on four main aspects of haptic information (roughness, compliance, coldness, and slipperiness), which are perceived through human tactile sensors. By using statistical analysis, the correlation between each hierarchy was obtained, and the preference was derived in terms of physical measures. A verification test was conducted by using unknown samples to determine the reliability of the system. The results showed that the system developed was capable of estimating preference with an accuracy of approximately 80%.
An ultrasonic motor is generally composed of a vibrator and a rotor, and is driven by the frictional force between the vibrator/rotor. Since the contact points on the vibrator draw elliptic trajectory, relative speed of the point against the rotor varies even when the rotor rotates with a constant speed. This may cause abrasion between the vibrator/rotor and decrease in driving efficiency. This research proposes a novel method to reduce the relative speed to improve the driving efficiency of ultrasonic motors by superimposing harmonic vibrations with driving vibration. Results of numerical calculation show that driving efficiency may be improved by 27% by the proposed method.
An ultrasonic motor is generally composed of a vibrator and a rotor, and is driven by the frictional force between stator/rotor. Since the contact points on the stator draw elliptic trajectory, relative speed of the point against the rotor varies even when the rotor rotates with a constant speed. This may cause wear and a decrease in efficiency. This research proposes a novel method to reduce the relative speed variation to improve the efficiency of ultrasonic motors by superimposing harmonic vibration with driving vibration. Results of numerical calculation show that the efficiency may be improved by 27 % by the proposed method.
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