full Paper - Nguyen Dang Binh

EUROGRAPHICS 2005 Tutorial
Haptic Interfaces for Virtual Prototyping
M. Bergamasco*, A. Frisoli, PERCROScuola Superiore S.Anna, Pisa, Italy
S. Scattareggia Marchese,Signo Motus srl - Messina, Italy
A. Gucciardino, Direzione Generale Armamenti Terrestri - Rome, Italy
Abstract
This paper analyzes the general requirements of Haptic Interfaces (HIs) for Virtual Prototyping operations. In
particular two different paradigms of interaction with virtual objects are presented, respectively based on an
anthropomorphic and a desktop Haptic Interface. The main aspects of mechanical and control system design of
HIs and force rendering in Virtual Environments are discussed too. The experimental results of the simulations
conducted with a force feedback arm exoskeleton are presented, pointing out the current limits of the existing
devices and outlining the future developments.
1. Introduction
Virtual prototyping technologies can reduce the time and
costs necessary to develop and construct new products and
bridge the disciplinary and distance gaps among different
collaborators working on the same project [3]. Virtual Prototyping
is based on the simulation in a realistic threedimensional
Virtual Environment of the functionality expected
from the new product. Before the real construction of
the first prototype, it enables designers to evaluate the fulfillment
of ergonomics, engineering and design requirements,
and the feasibility/adequacy of the product to the foreseen
usage [2]. One of the key issues in Virtual Prototyping applications
is the capability provided to the operator of interacting
in an efficient and sensorially sufficient way with the
virtual model of the object. The sense of touch appears to
be fundamental to assess the properties of the prototype of
a complex system, such as a vehicle. Although CAD systems
are becoming widespread, there is still some important
information that a CAD program alone cannot supply.
The designer cannot see from the CAD how the operator
will fit into cab or assess how the controls will feel during
operation. During the development of new vehicles the designer
must still wait until a mock-up or a prototype is built
to find out how the controls feel and whether or not they
are easy to use [1]. Vehicle simulators immersed in Virtual
Environments [6][4], where either the contact or the inertial
forces are replicated to the operator, have been successfully
employed for the evaluation of ergonomics aspects in
the cockpit. Conceptually the rendering to the human operator
of the sensation of a physical interaction with a vir-
c­ The Eurographics Association 2005.
66
tual environment can be achieved by utilizing appropriate
interfaces capable of generating adequate sensory stimuli to
the operator. Such interfaces, called Haptic Interfaces (HIs),
are force feedback devices that can exert a controlled force
on the operator’s limb as if he was touching a real object.
HIs can greatly enhance the realism and the sensation of
immersion perceived by the operator in the Virtual Environment,
while using CAD tools for the design/assessment
of new products. The most important characteristics that an
HI must fulfill are high backdrivability, low inertia (related
with the transparency during the motion of the device), absence
of mechanical plays, mechanical stiffness greater than
5 N/mm, isotropic force response in the workspace (necessary
to avoid vibrations and penetration into virtual objects).
The low-level control system needs to run with a frequency
up to 1KHz and to maintain the coherence with the graphics
representation of the simulation. HIs, can be usefully employed
for the simulation of virtual assembly and maintenance
procedures, with the aim of studying the feasibility
of some particular mounting operations in mechanical assemblies
and verifying the level of operator’s tiredness induced
by the task. In particular in order to evaluate the execution
of such procedures in complex mechanical assemblies,
it is necessary to use HIs with a workspace close to the
real one of the human arm and with multiple contact points
on the operator’s arm. Force feedback anthropomorphic arm
exoskeletons, which can be worn by the operator in a natural
way with a reduced encumbrance, are the ideal candidate
solutions for the simulation of such complex tasks. The possibility
of exerting contact forces on different points of the