Fabrication and Characterization of Pneumatic Unit Cell Actuators

In the realm of virtual and augmented reality (VR/AR) and teleoperation applications, haptic feedback plays a role in enhancing task performance. One of the main goals of this study is to simplify haptic device hardware while improving its capacity to provide various stimuli at different intensities. In response to these challenges, this research introduces the Pneumatic Unit Cell (PUC), a soft pneumatically driven device—a hollow silicone cylinder with the ability to provide both static-pressure and vibrotactile feedback. Furthermore, the Pneumatic Unit Cell’s design simplicity has the potential for scalability, modularity, and the flexibility to mount the device on any part of the human body. The focus of the current paper is to study PUCs as actuators and lay the foundation for future perceptual studies. The characterization studies encompass the fabrication and verification of the fabrication accuracy through dimensional measurements, characterizing PUCs under static-pressure conditions (measuring the free deflection and blocking force) and frequency conditions (measuring the free deflection). In the static-pressure conditions, we applied pressures ranging from 0 to 40 kPa to measure the free deflection and from 0 to 30 kPa to measure the blocking force. In the frequency conditions, we applied pressures of 10, 20, and 30 kPa with inflation/deflation rates varying between 0.5 Hz and 100 Hz. The measurements of free deflection under static-pressure conditions revealed that 0.9 mm and 1.2 mm PUCs exhibit a linear increase in free deflection with an increase in inflation pressure. The results of free-deflection measurements under the frequency conditions indicate a direct relationship between the free-deflection magnitude and applied pressure. The results also demonstrate an inverse relationship to the frequency of inflation/deflation. The characterization results demonstrate a broad range of free deflection observed under both static-pressure and frequency conditions, encouraging the potential application of Pneumatic Unit Cell actuators as haptic devices.