Rendering stiffer walls: a hybrid haptic system using continuous and discrete time feedback

Authors: Vasudevan, Hari¹; Srikanth, Manohar B.²; Muniyandi, Manivannan¹

Source: Advanced Robotics, Volume 21, Number 11, 2007 , pp. 1323-1338(16)

Buy & download fulltext article:

Price: $35.00 plus tax (Refund Policy)

Abstract:

Instability in conventional haptic rendering destroys the perception of rigid objects in virtual environments. Inherent limitations in the conventional haptic loop restrict the maximum stiffness that can be rendered. In this paper we present a method to render virtual walls that are much stiffer than those achieved by conventional techniques. By removing the conventional digital haptic loop and replacing it with a part-continuous and part-discrete time hybrid haptic loop, we were able to render stiffer walls. The control loop is implemented as a combinational logic circuit on an field-programmable gate array. We compared the performance of the conventional haptic loop and our hybrid haptic loop on the same haptic device, and present mathematical analysis to show the limit of stability of our device. Our hybrid method removes the computer-intensive haptic loop from the CPU—this can free a significant amount of resources that can be used for other purposes such as graphical rendering and physics modeling. It is our hope that, in the future, similar designs will lead to a haptics processing unit (HPU).

Keywords: HAPTICS; INSTABILITY; PASSIVENESS; CONTINUOUS TIME; PROGRAMMABLE LOGIC DEVICES

Document Type: Research article

DOI: http://dx.doi.org/10.1163/156855307781503745

Affiliations: 1: Indian Institute of Technology Madras, Chennai 600036, India 2: Indian Institute of Science, Bangalore 560012, India

Publication date: 2007-11-01