AS
A. Sabbadini
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1
When we manipulate objects in our day-to-day life, we perceive information on the object via force feedback that we sense with our sensorimotor system. However, in virtual reality, we lack these forces, which makes it more challenging to interact with the digital world. Wearables, such as hand exoskeletons, can provide force feedback in VR. Nonetheless, as the devices’ actuation or brake system is often bulky or heavy, users typically do not enjoy wearing them. In this study, we investigate the potential of a new friction-based mechanism that can address the existing issues. Our design adopts ultrasonic vibrations to generate a squeeze film, which is a well-studied phenomenon to decrease friction significantly. In literature, the phenomenon has only been investigated with vibrations from one side, with the goal of friction reduction. However, we show that by adding a vibrating surface opposite to the original one, we can extend the possibilities of squeeze films, enabling us to both decrease and increase friction. Since ultrasonic transducers can be miniaturized, our mechanism brings us closer to solving the size and weight issues of existing devices.
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When we manipulate objects in our day-to-day life, we perceive information on the object via force feedback that we sense with our sensorimotor system. However, in virtual reality, we lack these forces, which makes it more challenging to interact with the digital world. Wearables, such as hand exoskeletons, can provide force feedback in VR. Nonetheless, as the devices’ actuation or brake system is often bulky or heavy, users typically do not enjoy wearing them. In this study, we investigate the potential of a new friction-based mechanism that can address the existing issues. Our design adopts ultrasonic vibrations to generate a squeeze film, which is a well-studied phenomenon to decrease friction significantly. In literature, the phenomenon has only been investigated with vibrations from one side, with the goal of friction reduction. However, we show that by adding a vibrating surface opposite to the original one, we can extend the possibilities of squeeze films, enabling us to both decrease and increase friction. Since ultrasonic transducers can be miniaturized, our mechanism brings us closer to solving the size and weight issues of existing devices.
In this research, a Shive wave machine is used to study (a) the velocity of waves throughout different media and (b) the transition of waves between two different media. The Shive wave machine used in this research consists of 32 parallel aluminum bars attached perpendicularly to three parallel central wires. When a perturbation is applied to one of the bars, a torsional wave is initiated in the Shive wave machine, which is mapped to a transverse wave at the extremities of the bars. The velocity of a wave in the Shive wave machine is theoretically determined by four variables: (i) The distance between the two outside wires and the central wire; (ii) the tension in the two outside wires; (iii) the distance between the bars; (iv) the moment of inertia of the bars. The transition of waves between two different media is theoretically determined by the wave velocities in the two media. The theory states that a part of the wave is reflected and a part is transmitted at the intersection between the two media. The results for (a) show that the measured velocity is higher than theoretically expected, which may be caused by an incorrect measurement of (ii). The results for (b) show that a change in (i) throughout the system does not comply with the theoretically expected ratios for reflection and transmission, whereas a change in (iv) does comply with the theoretically expected ratios.
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In this research, a Shive wave machine is used to study (a) the velocity of waves throughout different media and (b) the transition of waves between two different media. The Shive wave machine used in this research consists of 32 parallel aluminum bars attached perpendicularly to three parallel central wires. When a perturbation is applied to one of the bars, a torsional wave is initiated in the Shive wave machine, which is mapped to a transverse wave at the extremities of the bars. The velocity of a wave in the Shive wave machine is theoretically determined by four variables: (i) The distance between the two outside wires and the central wire; (ii) the tension in the two outside wires; (iii) the distance between the bars; (iv) the moment of inertia of the bars. The transition of waves between two different media is theoretically determined by the wave velocities in the two media. The theory states that a part of the wave is reflected and a part is transmitted at the intersection between the two media. The results for (a) show that the measured velocity is higher than theoretically expected, which may be caused by an incorrect measurement of (ii). The results for (b) show that a change in (i) throughout the system does not comply with the theoretically expected ratios for reflection and transmission, whereas a change in (iv) does comply with the theoretically expected ratios.