HANDS.DVI
A DeVice-Independent programming and control
framework for robotic HANDS
Università di Siena , Università di Pisa and Istituto Italiano di
Tecnologia
HANDS.DVI Kick Off Meeting @ IIT, January 2011
ECHORD
ECHORD (European Clearing House for Open Robotics
Development) is a EU funded project aiming to strengthen the
cooperation between scientific research and industry in robotics.
However, finding common ground between manufacturers and the
research community, especially when it comes to defining the future
direction of robotics research, has proven difficult in the past.
ECHORD will act as a "clearing house" to streamline successful
know-how transfers.
ECHORD is coordinated by Technical University of Munich.
The experiments are the ECHORD projects.
The problem
Because of their intrinsic complexity, there is not a standard approach
to the control of grasping and manipulation tasks. Borrowing the
terminology of software engineering, there is a need for middleware
solutions for manipulation and grasping tasks to seamlessly integrate
robotic hands in flexible cells.
The project’s idea
The abstraction layer is based on sensorimotor synergies.
Synergies with the The Hand Embodied EU project.
Sensorimotor synergies
Recent results on the organization of the human hand in grasping
and manipulation are the inspiration for this project proposal: these
results have demonstrated that, notwithstanding the complexity of
the human hand, a few variables are able to account for most of the
variance in the patterns of human hands configuration and
movement.
(Simulations by UNIPI)
Hands controlled with few knobs
The main points
The paradigmatic hand:
``A trade–off between the complexity of the human hand model
accounting for the synergistic organization of the sensorimotor system
and the simplicity of the models of robotic hands available on the market.
‘’
Postural synergies
``The paradigmatic hand will be developed to define a basis of
synergies that will allow to design simplified strategies for the control of
grasping forces. Here, the number and the structures of the force
synergies will be defined.’’
Projecting synergies to the robotic hands with dissimilar kinematics
``Theoretical tools to design a suitable mapping function of the control
action (decomposed in its elemental action, synergies) from the
paradigmatic hand domain onto the articulated hand co-domain.
The definition of this mapping is the core of HANDS.DVI.
Experiments
``The experiment consists of 3 robotic hands and an instrumented
object with force sensors.’’
Simplifying assumptions: objects
With reference to the taxonomy [Curkosky],
the
different
postures
proposed
in
HANDS.DVI for the experiments will be
- a power/prehensile/prismatic/heavy wrap
grasp, also named cylindrical, characterized
by a large diameter of the cylinder involved;
a
power/prehensile/circular
grasp,
characterized by a spherical configuration;
- a precision/prismatic grasp, characterized by
the opposition of the thumb and the other
fingers.
Ranging from heavy wrap power grasps to
precision grasps, the above postures cut
across the whole grasp choice space and,
therefore, can be considered representative of
the most common grasps a robotic hand
would be asked to realize in hyper-flexible
cells.
Simplifying assumptions: contacts
The force sensors are fixed to the object
that will be referred to as the instrumented
object.
The instrumented object can
change its shape but has given and fixed
contact points. This is not a limitation since
the focus of HANDS.DVI is on the control of
contact force interaction and not on the
approaching phase where the choice of
contact points is important
For a given shape of the object we will a–
priori choose the optimal position of contact
points on the object surface.
task EXP
task DVI
task SYN
Three Tasks (UNISI,UNIPI,IIT)
HANDS.DVI
Industrial
Gripper
Cooperati
ve
Manipulators
Barrett
Hand
DLR II
Hand
Shadow
Hand
Mar ‘11
Jul ‘11
Jul ‘11
Jul ’11
Jan’12
May’11
Mar’12
’
Preliminary results UNISI
The paradigmatic hand
- Kinematic model of the hand @ UNISI (20 DoFs)
Matlab toolbox for grasp analysis with
synergies
Hand kinematic
structure (via DH
parameters)
Hand
reference
configuration
Synergy matrix
definition
Grasped object:
search the
contact points
Grasp Analysis
Grasp optimization tools
Task space mapping with ellipsoids
Middleware
Real hand
synergies
synergies ?
In the task frame. Object-oriented.
- compute the ellipsoids (force/manipulation) associated to the synergies
in the paradigmatic space
- assign those ellipsoid to the same object but with the real hand
- with an inversion problem compute the synergy mapping
This is the synergy mapping for a given object and a given set of
contacts.
Literature review
- Eingengraps
- Mapping approaches (virtual finger)