We often interact with our environment through manual handling of objects and exploration of their properties. Object properties (OP), such as texture, stiffness, size, shape, temperature, weight, and orientation provide necessary information to successfully perform interactions. The human haptic perception system plays a key role in this. As virtual reality (VR) has been a growing field of interest with many applications, adding haptic feedback to virtual experiences is another step towards more realistic virtual interactions. However, integrating haptics in a realistic manner, requires complex technological solutions and actual user-testing in virtual environments (VEs) for verification. This review provides a comprehensive overview of recent wearable haptic devices (HDs) categorized by the OP exploration for which they have been verified in a VE. We found 13 studies which specifically addressed user-testing of wearable HDs in healthy subjects. We map and discuss the different technological solutions for different OP exploration which are useful for the design of future haptic object interactions in VR, and provide future recommendations.@en

Parkinson’s Disease (PD) is one of the most common neuro-degenerative diseases worldwide, affecting patients’ ability to perform Activities of Daily Living (ADL), such as cooking and dressing, and consequently decreasing Quality of Life (QoL). Most ADL require dexterous skills which are often impaired in PD. Pharmacological therapy is often not completely effective and hasside effects. Tailored and engaging rehabilitation interventions aimed at practicing such dexterous ADL are therefore necessary at different stages of the disease. Besides the traditional physical and occupational interventions, Virtual Reality (VR) technology has proven a viable tool to facilitate such rehabilitation programs by providing flexibility in design and simultaneously creating pleasant and immersive environments. It is suggested that implementing haptic feedback into a Virtual Environment (VE) could further boost motor learning during training and improve patients’ compliance to the practise. Till date, haptic feedback during VR training, has not been evaluated in PD. The purpose of the present study was twofold. First, a novel VR haptic glove system, consisting of existing VRFree gloves integrated with a Haptic Device (HD) to provide Vibrotactile Feedback (VTF) throuh the use of Linear Resonant Actuators (LRA)s, was developed. This newly developed system was then technically tested with regard to its latency, intensities and compatibility. Second, the system was evaluated on its performance and usability in both healthy subjects and PD patients by means of a novel VR grasping task. Technical tests yielded positive results; a latency of 13 +- 12 ms is found, the HD is able to convey different intensities and the HD produces no visually noticed interference with the VRFree gloves. The user tests revealed positive results on increased grasp performance with the VTF in terms of grasp time and smoothness among healthy subjects and a good Haptic Experience (HX) evaluation among all subjects. An average System Usability Scale (SUS) score of 75 suggest good usability of the overall system. This usability study demonstrates for the first time that VTF on the fingertips during VR rehabilitation is feasible to train dexterity related ADL in PD. Further studies will be needed to evaluate its value as a rehabilitation tool to improve QoL in PD.@en