Towards Stable High-Fidelity Kinesthetic Haptic Interaction

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Pecly, Leonam
Haptic device , Stability , Kinesthetic fidelity
Haptic simulation systems are developed to enable users to interact with virtual environments using an actuated mechanism, known as a haptic device. This real-time technology has found applications in robotics rehabilitation and training of medical professionals for minimally invasive surgery, dental procedures, or sonography. One major challenge in the design of these systems is simulating a wide range of environment dynamics, especially stiffness, with which a user can interact in a stable manner. This mainly relates to the use of digital platforms and their inherent latency due to the sample-and-hold process. Therefore, given the motivation to represent a wide stiffness range, this thesis presents the development of new techniques through analytical and experimental research that allow users to safely interact with a larger range of virtual environment dynamics and experience a more faithful feel of intended environment. The work presented here aimed to improve the system components including the development of more accurate haptic systems models and novel methods for digital and analog signal estimation. As typical haptic devices are only equipped with position sensors, access to velocity to implement virtual environments with high fidelity is a challenge. I have developed a novel method to estimate velocity improving the capability of haptic systems to simulate wider environment viscoelastic environment with enhanced realism. Moreover, the actuation system have also been explored through development of more accurate models and electronic drivers, which the results showed that current drivers tuned as proposed can significantly increase the system bandwidth and consequently enlarge the stiffness range and simulation fidelity. In addition, the estimation of reliable analog position for use in analog or hybrid virtual environment have shown that a stiffness range larger than 400\% with enhanced fidelity can be obtained compared to common digital viscoelastic virtual environment. Throughout this work I show that while some proposed solutions can be applied to current haptic systems, others can be used for the development of new ones.
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