Leghe a memoria di forma come tecnologia di attuazione per la biorobotica

Transcription

1 Leghe a memoria di forma come tecnologia di attuazione per la biorobotica Milano, 7 novembre, 2013 Maurizio Follador maurizio.follador@sssup.it

2 Advanced Education, Frontier Interdisciplinary Research and Exploitation of Research Results Paolo Dario, Director Cecilia Laschi, Deputy-Director The BioRobotics Polo Sant Anna Valdera Viale R. Piaggio Pontedera (Pisa) Tel

3 Research Areas Humanoid Robotics Neuro-Robotics Surgical Robotics Soft Robotics Neural Engineering (Paolo DARIO) (Maria Chiara CARROZZA) (Arianna MENCIASSI) (Cecilia LASCHI) (Silvestro MICERA) Biomedical Signal Processing (Angelo Maria SABATINI) Creative Design (Cesare STEFANINI) Future and Emerging BioRobotics (Paolo DARIO) Neurodevelopmental bioengineering Ambient Assisted Living and Service Robotics Marine Robotics Roboethics New research areas

4 Shape memory alloys at BioRobotics Institute Bergamasco et al Menciassi et al., 2004 Octopus Project, 2013 Araknes Project, 2012

5 OCTOPUS IP ( ) Novel Design Principles and Technologies for a New Generation of High Dexterity Soft-bodied Robots Inspired by the Morphology and Behaviour of the Octopus

6 Soft Robotics Soft robotics is not just a new direction of technological development, but a novel approach to robotics, unhinging its fundamentals, with the potential to produce a new generation of robots, in the support of humans in our natural environments. The role of soft body parts appears clear in natural organisms, to increase adaptability and robustness. Compliance, or softness, are also needed for implementing the principles of embodied intelligence, or morphological computation, a modern view of intelligence, attributing a stronger role to the physical body and its interaction with the environment.

7 Muscular Hydrostat: Constant volume during contractions Longitudinal Muscles Transverse Muscles Oblique Muscles The muscular system serves as a modifiable skeleton and allows the transformation of force into motion

8 Muscular Hydrostat: Constant volume during contractions All movements are combination of the three muscle bundles Local bending, stiffening, elongation and shortening are possible CONTRACTED RELAXED ELONGATION CONTRACTED RELAXED SHORTENING

9 Muscular Hydrostat: Constant volume during contractions BENDING CONTRACTED RELAXED

10 Muscular Hydrostat: Bioinspired artificial unit biological Transverse muscles artificial SMA Transverse actuation system Longitudinal muscles Longitudinal actuation system Embedding material Connective tissue Mechanical interface / containment PATENT PENDING

11 Single SMA spring actuator SMA springs working in water Working frequency of 1 Hz Operation current 1.2 A

12 Assembly of multiple units NON ACTIVATED ACTIVATED

13 Fabrication of an entire artificial octopus arm Transverse springs Longitudinal springs Longitudinal cables

14 Fabrication of an entire artificial octopus arm

15 Artificial arm capabilities Rest length Elongation Shortening Bending Multi Bending performed by local bends

16 Integration in the multiple-arm robotic octopus prototype SMA actuation Vision system ARM 1 Image: London Science Museum/Jennie Hills Manipulation arms b1 servomotor ARM 2 b2 orientation Locomotion arms mechanism Passive suckers

17 Grasping ability of the robot

18 Minimum grasping radius Grasping characterization Testing Radii [mm] Grasping Effectiveness, 50% distance from the tip Grasping Effectiveness, 30% distance from the tip 12.5 Fail Pass 17.5 Pass Pass 22.5 Pass Pass The effectiveness of the grasping strongly depends on the point where the object is grabbed. The use of a conical structure (instead of cylindrical) enables the possibility to grasp object of different sizes depending on the distance to the tip because of the spiral shape it forms when actuated

19 Operating limits angles Max angles achievable by SMA longitudinal springs Simple bending Operating Limit Angles [deg] Single change of convexity bending. Operating Limit Angles [deg] Double change of convexity bending Operating Limit Angles [deg] a0 85 a1 78 a2 76 b1 55 b2 44 c2 57

20 SURGICALROBOTS FOR MINIMALLY INVASIVE SURGERY

21 INTRODUCTION (A STEP THROUGH MINIMALLY INVASIVE SURGERY) LAPAROSCOPIC SURGERY ROBOTIC SURGERY ENDOSCOPIC TRANSLUMENAL SURGERY (NOTES) less invasive then open fast recovery performance improvement invasiveness comparable with laparo. Derived by endoscopes no external incisions less invasive then laparo. New instruments Miniaturized robotic systems

22 ARAKNES RESEARCH PLATFORM ( (TROCAR/NOTES ACCESS)

23 ARAKNES RESEARCH PLATFORM ( (TROCAR/NOTES ACCESS) DOCKING MECHANISM ANCHORING FRAME Assembly of modular components dependant by the features needed (electro-cut, gripper, etc) Safe in deployment and in cause of fault ROBOTIC MODULES

24 ANCHORINGFRAMESPECIFICATIONS Actively change configuration Guarantee a stable adhesion during surgical tasks Respect anatomical constrains during deployment Embed miniaturized actuators Experimental evaluation of anatomical constraints WHY SMA ACTUATION? SMA provide soft actuation and inherent compliant muscle-like behavior (low forces applied to the environment) Compatible with magnetic anchoring (it is hard to use electric motors close to permanent magnets) Easy to miniaturize, compact design is allowed! (it is possible to leave free space for magnets on the device)

25 FROM THE CONCEPT TO THE PROTOTYPE (BIAS ELEMENT DESIGN) ELASTIC BAND AS BIAS ELEMENT ELASTIC BAND AS SAFETY SYSTEM! THE GOAL IS TO PROVIDE A NON LINEAR TORQUE LAYING BETWEEN AUSTENITE AND MARTENSITE TORQUE

26 FROM THE CONCEPT TO THE PROTOTYPE (SMAANGULAR ACTUATORS FABRICATION) Constrain the SMA wire/sheet shape Thermal treatment ~500 deg (depends by the alloy composition) Repeat in order to reach desired shape 1 st thermal treatment 2 nd thermal treatment 3 rd thermal treatment

27 ANCHORING FRAME M. Salerno, S. Tognarelli, C. Quaglia, P. Dario, and A. Menciassi, Anchoring frame for intra-abdominal surgery, International Journal of Robotics Research, 2013.

28 ARAKNES RESEARCH PLATFORM ( (TROCAR/NOTES ACCESS) DOCKING MECHANISM ANCHORING FRAME Stable connection of robotic modules with the anchoring frame Cubic docking base shape exploited for constraining the rotations ROBOTIC MODULES 1 active degree of freedom to execute the docking

29 Conclusions SMA are still limited from the point of view of control The use of Shape Memory Alloys for actuation represents a technological opportunity for replacing the today's electro-mechanical actuators with simpler, more compact and reliable ones. Strong mixture of expertise From active and smart materials Leader in consumer electronics Leader in SMA providing and manufacturing To robust and reliable actuators

30 Thank you for your attention! Paolo Dario, Director Cecilia Laschi, Deputy-Director The Leghe BioRobotics a memoria Institute, di forma Scuola come Superiore tecnologia di Sant'Anna attuazione per la biorobotica Polo Sant'Anna Valdera - viale Rinaldo Piaggio 34, Pontedera (Pisa)