Modification of SFA to Enlarge the Impedance Range and Render High Stiffness Contact

Abstract

Virtual environments have become consistently widespread in various fields such as training simulations in aerospace or surgical medicine, gaming, and teleoperation systems. To make the experience more realistic, the use of haptic force feedback has become an essential research area. Nonetheless displaying a virtual object stably is still a challenge predominantly because of time discretization. This thesis explores the utilization of haptic force feedback and some advancements for the Successive Force Augmentation approach (SFA). As well as the implementation and the testing of these enhancements. The thesis begins by introducing the concept of haptic force feedback, some implementation fields and the importance of haptic feedback in enhancing user immersion, presence, and overall experience in virtual environments. Furthermore, different challenges and limitations in haptics are discussed and important concepts are explained. The thesis then delves into two currently used approaches for generating realistic haptic feedback: the Time-domain Passivity Approach (TDPA) and the Successive Force Augmentation approach (SFA). The thesis explains the main idea, their algorithm and implementation. Next, the thesis explores the new enhancements for the SFA to avoid oscillations near the virtual wall, to steer clear of singularities by very high stiffnesses and to accelerate and optimize the reaching of the desired stiffness. Afterwards, the theory of these enhancements were implemented and tested through computer simulation, real hardware verification and a user study. This multifaceted evaluation is reported in this thesis. In conclusion, this thesis highlights the importance of haptic force feedback and proves the new advancements for the Successive Force Augmentation approach in enhancing user interaction and perception in virtual environments.