# Integrated Haptic Feedback with Augmented Reality to Improve Pinching and Fine Moving of Objects
## 5 Conclusions  
Pinning and fine movement of objects, particularly the use of the pincer grasp, are essential fine motor skills. Integration of haptic feedback with augmented reality can be useful to notify the user when this gesture is recognized. Additionally, this feedback helps compensate for any misalignment in visual perception between the tracked fingertip and virtual objects, leading to improved spatial precision. Our results show that the median distance error (with IQR) on all three axes varied significantly across different conditions. The bare-hand condition had the highest median distance error, of 10.3 mm (IQR = 13.1 mm), and the slowest execution time of 10.0 s (IQR = 4.0 s). The bHaptics glove improved performance, resulting in a lower median error of 2.4 mm (IQR = 5.2 mm) and an execution time of 8.0 s (IQR = 6.0 s). The haptic rings achieved the highest precision, with the lowest error of 2.0 mm (IQR = 2.0 mm) and the fastest execution time of 6.0 s (IQR = 5.0 s). Based on our experiments, it is possible to improve performance in terms of execution time without sacrificing spatial accuracy. However, the results may vary depending on the haptic device used. Simpler devices, such as the described haptic rings, can outperform more complex devices like the bHaptic gloves, offering enhanced accuracy and faster execution times. The haptic gloves may face challenges with tracking the hand and fingers, particularly when relying on the video-based tracking provided by the Microsoft HoloLens 2. Moreover, the haptic rings are also superior in terms of wearability. This study holds significant promise for future research and practical deployments, especially in fields that require high levels of precision and depth perception. One of the most impactful areas can be surgical training and guidance, where haptic feedback can help prevent critical errors, such as penetrating incorrect tissues or organs. Additionally, it can assist users in comprehending the spatial depth of their environment, an essential factor in various professional applications beyond healthcare, including robotics, industrial design, and remote manipulation. The experimental approaches described in this paper can also be applied in the future to other gestures, such as power grasping.  
Conceptualization, J.H. and V.F.; Methodology, J.H., M.B. and V.F.; Software, J.H.; Validation, J.H. and M.B.; Formal analysis, J.H. and M.B.; Investigation, J.H.; Resources, J.H., M.B. and V.F.; Data curation, J.H.; Writing--original draft, J.H.; Writing--review & editing, M.B. and V.F.; Supervision, M.B. and V.F.; Project administration, V.F.; Funding acquisition, V.F. and M.B. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the Italian Ministry of Education and Research (MUR) in the framework of the ForeLab Project (Departments of Excellence), in part by the European Union by the Next Generation EU Project ECS00000017--Tuscany Health Ecosystem (THE, PNRR, Spoke 9: Robotics and Automation for Health), in part by the Italian Ministry of University and Research (MUR)--Fondo Italiano per la Scienza (FIS), under PERCEIVING Grant FIS00001153, in part by the Project 'EXPERIENCE' through European Commission H2020 Framework Programme under Grant 101017727.  
The study was conducted by the Declaration of Helsinki, approved by the Bioethics Committee of the University of Pisa (resolution n. 51/2024 of 27 September 2024).  
All the participants enrolled signed an informed consent that included also the consent to publish any media (photos and videos) from the trial.  
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
We would like to thank [PERSON] for the technical support in developing the haptic rings.  
The authors declare no conflicts of interest.  
The following abbreviations are used in this manuscript: