Haptic feedback is essential for achieving virtual and augmented reality (VR/AR) systems with high fidelity and realism. Haptic-enabled VR/AR systems offer a proficient environment in which to enhance the skills of medical practitioners. While pneumatic actuation is traditionally used in heavy automation industries, haptics researchers have utilized pneumatic techniques to produce various haptic effects, i.e., stiffness feedback and contour control, and these techniques have shown promising results in the medical domain. In this paper, we focus on the use of pneumatic-actuated haptic systems in VR/AR-based medical simulators. We begin with the taxonomy of the physical-virtual continuum and discuss the role of pneumatics in medical haptic systems. Furthermore, we propose the conceptual design architecture of a pneumatic haptic system. In addition, the systematic state-of-the-art role of pneumatic haptics in medical systems is presented for different categories. In this paper, we provide a systematic review and discuss the study of pneumatics to provide guidelines for the design and development of pneumatic haptic medical systems.

This paper presents a novel finger-worn actuator capable of generating three distinctive haptic effects: static pressure, high-frequency vibration, and an impact. Our new design makes this multi-mode feedback with a single actuator possible in a small form factor. A ring-shaped air bladder made with soft silicone is inflated or deflated to generate feedback on the finger. The airflow is controlled by a pair of air valves connected to a compressed air tank. Besides static pressure, the actuator can generate high-frequency vibration with high acceleration and crisp impact feedback due to fast controllability of the valves with a strong air source and a lightweight bladder membrane. In addition, our special design and fabrication of the bladder – a combination of stretchable and non-stretchable membrane layers in the ring – allows for stronger feedback. Rendering algorithms for three kinds of feedback are also presented. The performance of the system and the characteristics of the feedback are thoroughly examined using a series of measurement experiments, revealing that the system can generate a static force up to 6.3 N, the vibration up to 2.2 g magnitude and 250 Hz frequency, and an impact with less than 5 ms of latency. The whole system weighs only 255 grams (4.5 grams for the actuator and 250 grams for the controller). Finally, we demonstrate the wearability of the system by integrating the modules into a self-contained haptic device in the form of a wristlet.

The ability to deliver sensations of human-like touch within virtual reality remains an important challenge to immersive, realistic experiences. Since conventional haptic actuators impart distinctively unnatural effects, we instead tackle this challenge through the design of a rendering mechanism using soft pneumatic actuators (SPA), embedded within a wearable jacket. The resulting system is then evaluated for its ability to mimic realistic touch gesture sensations of grab, touch, tap, and tickle as performed by human fingertips. The results of our experiments indicate that the stimuli produced by our design were reasonably effective in presenting realistic human-generated sensations.

 We present an interactive virtual-reality (VR) fire extinguisher that provides both realistic viewing using a head-mounted display (HMD) and kinesthetic experiences using a pneumatic muscle and vibrotactile transducer. The VR fire extinguisher is designed to train people to use a fire extinguisher skillfully in real fire situations. We seamlessly integrate three technologies: VR, object motion tracking, and haptic feedback. A fire scene is immersed in the HMD, and a motion tracker is used to replicate a real designed object into the virtual environment to realize augmented reality. In addition, when the handle of the fire extinguisher is squeezed to release the extinguishing agent, the haptic device generates both vibrotactile and air flow tactile feedback signals, providing the same experience as that obtained while using a real fire extinguisher.