Vertebrate- or snake-like soft robot based on tensegrity principle...
Transcript of Vertebrate- or snake-like soft robot based on tensegrity principle...
Vertebrate- or snake-like soft robot based on tensegrity principle
Présentation GT5,
vendredi 28 novembre 2014
Alex Pitti, phDMaître de Conférence, chaire d'excellence UCP-CNRS
Laboratoire ETIS CNRS, ENSEA, Cergy-Pontoise University
Research aims
Biologically-inspired solutions to challenge control of dexterous robots
- dimensionality (high number of DoF)
- exploiting the physics of the material (elasticity, friction) and of the robot morphology
- large repertoire of behaviors (walking, breaking, jumping, postural control)
Some solutions I attempt to propose:
Mechanism of phase synchronization in dynamical systems
- control the system's global dynamics- “tuning” to the material property and system morphology- applied to high dimensional system
The body design to process morphological computations
- geometry, structure
- material properties
based on previous works [Pitti, 2005~]
the controller
the robot
Hard materials are Hookean (mostly linear)Soft tissues are non-Hookean (visco-elastic)
'' always in tension (pre-stressed, muscle tone)
[Gordon : « Structures or why things don't fall down »]
The body's material properties are soft (muscles tissues and bones),≠ actual robot are engineered with hard materials (steel, plastic)
The robot : physical embodiment 1, material
[Tulving, 2005]
[Gordon : « Structures or why things don't fall down »]
[Gordon, 1994]
physical embodiment 2, the structure
The body structure (morphology) plays a role of a function in behavior→”morphological computations”, [R. Pfeifer]
Actual robot designer starts to have these considerations in mind.
[Lipson, 2004]
Changing the paradigmWe may see the musculo-skeletal system as a network of tension links (muscles, tendons) connected to compression structures (bones) : Pre-stressed structure.
Pretty much-like tensile structures.
Tensegrity structureTensegrity = integrity of tension proposed by B. Fuller & Sneil
network of tension and compression structure.
[Fuller and Sneil]
Tensegrity structureTensegrity = integrity of tension proposed by B. Fuller & Sneil
network of tension and compression structure.
➔ No momentum (no tangential force ≠ Newton laws & actual robots)➔ Ecological distribution of forces on all the structure:
➔ less power consumption to move➔ Exploit fully the physic of the structure:
➔ Light-weight structure➔ Self-replicative with lots of redundancy
➔ More robust & solid to defects/shocks➔ Self-Balance and neutral posture:
➔ return back to its own stable equilibrium
for arbitrarily small perturbations
[Tulvey 2013]
Tensegrity structure in biology Tensile links (muscles) support the structure weights (bones), not the
reverse
Shun Izawaya[Pfeifer Pitti 2012]
[Flemons, 2006]
Tensegrity robots
[Riesel 2012]
Nasa satellite antenna[SunSpiral, 2012]
[Shibata 2009]
design principles: – Muscles redundancy for compliance– Morphological computations: structure = function– Weak and loosely distributed units
Prototypes done [2011~]➔ Joint link device
➔ Snake-like or trunk-like tensile robot
Current snake prototype➔ Snake-like or trunk-like tensile robot
Anguilliform models
Representation of the swimmer as a chain ofinterconnected links. [McMillen 2008]
Snake skeleton
A proposed model of CPGs for multi-DOFs
Chaotic systemUnknown dissipative system
?
γ is a global parameter to control synchronization (motor synergy)State of feedback resonance in the dissipative system [Fradkov, 1999]
Model-free mechanism
For some specific coupling, Chaotic systems will match the system dynamics
1 Perturbation
2 Feedback
4 Resonance
3 Synchronization
[Pitti, 2005-2011]
Simulations of multi-DOF robotsRing-like mass-spring damper system (30 DoF) [Pitti, 2005]
Dog-like system (2 DoF) [Pitti, 2006]
Fréquence (H
z)
Control Parameter
Frog-like systems[Niiyama, Pitti, 2009]
chaoticcontrolers
Snake-like robotModel with 10 servos and 200ms delay sinusoidal oscillators with 5 segments
[done with Julien Abadji]
top view side view
Snake-like robot, current versionModel with solenoids (electro-magnets) and chaotic controllers (logistic map)
electro-magnets chaotic controller
body
Morphological computationown facial somatopic information
Ear 3D printed
Micro
[Pitti, 2012]
Audio spectral filtering done by shape of the ear
Time [s]
Fre
q [H
z]
… can serve for facial processing
[Pitti, 2013]
to conclude
How to make a robot that perceives like humans?
Understanding human intelligence(s) by synthetic or constructive approaches.
- To bridge the level of explanations
between Engineering, Biomechanics
Robotics/Comp. Science/Info. Theory
Developmental Psychology
Cognitive Neuroscience
- Seeking for design principles
- Reproducing it with robots Rolf Pfeifer and Alex Pitti
Manuella Editions, 2012
Rolf Pfeifer, ETH Zurichmoves
thinks
Save the date:
Journée GT8 Robotique et Neuroscience 17 décembre, UPMC
Cognitive Robotics and Enactive Systems
co-organizers
Benoît Girard, Medhi Kamassi, Ghilès Mostafaoui, Alex Pitti
Thank you
Architect projectJB Mouret, 2014