Uncoupled Stability of Haptic Simulation of Viscoelastic Virtual Environments

Haptic simulation systems enable users to kinesthetically interact with virtual environments through interaction with a robotic mechanism, known as a haptic device. Application of these systems are in medical simulators, robotic rehabilitation, and entertainment. Viscoelastic medium is a common environment that is simulated as a virtual environment (VE) in haptic simulation systems. Kelvin-Voigt (KV) and Hunt-Crossley (HC) are models commonly used to simulate viscoelastic environments in haptic simulation systems. Due to the sample-and-hold process, the range of dynamics - viscosity and elasticity, that can be rendered in a stable way is limited. While uncoupled stability, as a stringent stability condition, has been analyzed for KV VEs, it has not been evaluated for HC environments. In this thesis, we experimentally evaluate the range of dynamic parameters for each model that result in uncoupled stability. To compare the results, we map the HC parameters to the KV parameter space. Results show that higher values of n_HC are more suitable for interactions with stiffer environments, at the expense of damping, and compared to the dynamic range obtained from using KV VE, the HC model offers lower stiffness but higher damping range. To confirm the mapping, we conduct a user study to compare the viscosity and elasticity effects perceived by the users. Results show that different penetrations may not affect the stable HC elastic and viscous ranges, but it affects the feel of the HC modeled environment, as is reflected by the identified KV ranges, which confirms that the HC model is penetration dependent. In addition to determining the stable implementable range of HC and KV parameters for non-deformable environments, the stable implementable range of physical deformable objects implemented as a VE is also found. Physical gels with known Young’s Moduli are experimentally tested to determine their point of contact apparent stiffness and damping for varying penetration. These parameters are utilized to implement a spring-mass-damper mesh VE model for each gel. These values are also interpolated and extrapolated to implement a larger range of deformable VEs for uncoupled stability tests. The results show a viscoelastic dynamic range that depends on the depth of penetration.

Department dc:contributor.department

Electrical and Computer Engineering

Author dc:creator

• Oliver, Seanna M.

Advisor dc:contributor.supervisor

• Hashtrudi-Zaad, Keyvan

• Virtual Environment
• Haptic System
• Deformable
• Non-deformable
• Hunt-Crossley
• Kelvin-Voigt
• Uncoupled Stability
• Viscoelastic

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/32077

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/32077