A new dexterous robotized instrument tip for mini

EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
A new dexterous robotized instrument tip
for mini-invasive surgery,
based on flexible mechanisms
and miniature hydraulic actuation
Solano B. and Rotinat-Libersa C.
CEA LIST (France)
A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Surgical context and technological challenges
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Challenge of MIS
From MIS, through SILS, to NOTES
To penetrate the patient through a ∅ 5 mm trocar
Enough degrees of freedom inside the body to realize the suturing gesture (= gold standard gesture)
Technological limitations of classical articulated mechanical architecture and
motors at this scale
Expensive and not completely adapted to sterilization
Limited number of intracorporeal d.o.f. → limited dexterity → limited application field
Commercial instruments (manual) :
CambridgeEndo (∅ 5 mm : Roll – ±90°pitch – gripper) ⇒
REALHand® - Novare Surgical (∅ 5 mm : ±90°Pitch – roll – gripper)
Radius Surgical System (∅ 10 mm : ±70°Pitch – gripper) ⇒
Research instruments (motorized) :
INKOMAN -Technische Universität Darmstadt (2 х ± 90°pitch – 90°pitch – transl. – gripper)
Scuola Superiore Sant’Anna (Roll - 90°Pitch – roll – grip per)
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CambridgeEndo
Radius Surgical System
CEA LIST research objective
Intracorporeal motorized instruments (hand-held or robotized)
Replace classical design assemblies
Evaluate new concepts and technologies adapted to new mini-invasive robotic systems
development
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Development of a new dexterous robotized MIS device
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2008-2010 funding from the 2007 ANR TecSan (French National Research Agency
research program) : MIS application field
Evaluation of new structures and actuation technologies
for integration inside small cross-section instrument for better ergonomics and dexterity
Validation by designing and prototyping a ∅ 5 mm hand-held robotized instrument
adapted to the suturing gesture in mini-invasive conditions
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Architecture of the robotized device, compared to commercial manually driven
instruments
4 external d.o.f. produced directly by the surgeon hand or motorization
1 translation and 3 rotations
intracorporeal distal tip supported by the main shaft of the device, linked to a control
handle
3 intracorporeal d.o.f.
Deported
motorization
roll – pitch – roll mechanism
needle holder (at the distal extremity)
all motorization embedded (outside the body)
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New technologies to be evaluated by CEA LIST
new miniature hydraulic actuation
new monolithic compliant structures
Deported
motorization
Integrated
actuator
potential of miniaturization and integration
relatively good efficiency and low cost
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Miniature hydraulic actuation (1/2)
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Design of robotized surgical or medical tools, with a high number of
intracorporeal d.o.f. needs actuators …
… that can be integrated near the intracorporeal articulation to be controlled, to
avoid …
… performances and integration limitations due to classical commercially used technologies
(e.g. deported actuation and transmission using cables)
… mechanical couplings and interactions between the numerous articulations
… with quite ambitious mechanical performances
mechanical energy around 100 mJ
force of 3 to 10 N
low encumbrance (to be integrated in ∅ 5 mm embodiment)
but commercial actuators dealing with the required encumbrance constraint
doesn’t produce enough mechanical energy, e.g.
Piezoelectric-motors (inch-worm)
DC linear actuators
Squiggle 1.8
0,5 N / 5 mm
(2,8 × 2,8 mm)
E = 3 mJ
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Series 03A_S3
7 N / 2,8 mm
(Ø 3,4 mm)
E = 20 mJ
Chosen concept : new Mc Kibben type miniature muscle
development of a 1.5 mm diameter / hydraulic muscle with high performances
silicone tubing and nylon sleeves
Muscle lg 61 mm
6 N / 12.5 mm
E > 75 mJ
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Miniature hydraulic actuation (2/2)
• Physical behavior model
Predicts the force-displacement characteristics of a muscle from its given initial
geometry, material properties and the displacement of the fluidic circuitry piston
(i.e. the motor)
contracted length of the muscle (L) is a function of the displacement of the piston (∆Lp)
force is related to the pressure inside the fluidic circuitry (Pa = P – P’)
• Experimental validation of the non-linear model
Stroke performances under external loading
Fluid condition : pressure / displaced volume
Performances :
contraction rate around 20% (P alim = 1 MPa)
can produce up to 10 N force
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Compliant structures (1/3)
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Distal tip : d.o.f. architecture based on structural compliance
3 intracorporeal functions :
pitch structure
distal roll transmission structure
gripper structure
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Schedule of conditions : articulation and gripper
Pitch : 90° bending under external 75 mN.m torque
Distal roll : 270° rotation of the gripper base
a 3.2 diameter spring is used to transmit an external rotation movement to the distal tip,
by passing through the pitch articulation
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Gripper : 60° opening/closing and 3-10 N gripping force
Theoretical study
Design, optimization and dimensioning of each compliant structure
Experimental study
Observe their real performances under different loading conditions, close to
those encountered during the use of the device
Validate simulations and developed models to allow an optimization step of
these devices
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Compliant structures : pitch articulation (2/3)
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Theoretical performances objectives
less than 10 mm length
90° bending under 75 mN.m external torque
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elastic deformation during use of the device : PEEK material
Experimental performances of elementary prototype (pitch + distal roll
transmission)
Without suturing interaction forces, an actuation force of 8.5 N is needed to
bend the articulation to 90°
Fact
With suturing interaction forces
Fext
an external parasitic force in the bending opening direction leads to the rise of the
actuation force needed
- maintain 0° : 4,5 N act / 0,2 N ext
- maintain 90° : 11 N act / 0,1 N ext
- reach 90° : 14 N act / 0,3 N ext
- deviation at 90° : -60° / 1,3 N ext
Fex
t
a transversal parasitic force reveals the transverse stiffness of the articulation
- 20°/ 1 N ext.
Fext
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Compliant structures : gripper (3/3)
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Performances objectives : to catch the needle and tighten it strongly
8 mm length
60° opening/closing with two mobile jaws
gripping force strength enough to maintain the needle (3-10 N)
Optimal synthesis and dimensioning of a compliant gripper
Non intuitive optimal design obtained, using FlexIn, a software developed at
CEA LIST since 2001
uses an evolutionary algorithm approach, which allows true multi criteria optimal
synthesis of planar flexible mechanisms, considering assemblies of basic compliant
building blocks chosen in a given library
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Theoretical performances obtained
compliant gripper (Ti alloy)
small size (18 mm long, 4 mm wide) and small actuator stroke needed (0.7 mm)
but less than 1 N maximum tightening strength (with a 10 N actuator)
optimized articulated gripper (performance comparison basis)
6 N gripping force (with a 10 N actuator)
but larger encumbrance of the device
- needs a stroke of 3.5 mm (corresponds to a 20 mm-longer actuator)
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Validation prototype of the distal part (1/2)
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∅ 5.5 mm prototype of the distal part of the
instrument
Integration of the new building blocks developed
new miniature hydraulic actuation
New monolithic compliant articulations
Embedded motorization unit
fixed on the instrument main shaft (outside the patient body)
controlling the three distal d.o.f.
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d.o.f. motorization details
Pitch
use of a transmission cable
miniature motor placed in the motorization unit
Distal roll (compliant universal / cardan joint)
miniature motor placed in the motorization unit
Gripper (needle holder) : demonstrate integration
potential of new miniature hydraulic actuation
miniature hydraulic actuator integrated locally (between the
articulation and the gripper)
fluid is brought to the muscle by a soft pipe (never disturbances
nor coupling on the bending articulation or the distal roll)
closed fluidic circuitry embedded
hydraulic pressure inside the muscle is generated using a
miniature motor placed inside the motorization unit
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Validation prototype of the distal part (2/2)
• Video (1/2) : 3 d.o.f. movement
prototype with articulated gripper
• Performances
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Validation prototype of the distal part (2/2)
• Video (2/2) : 3 d.o.f. movement
prototype with compliant gripper
• Performances
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Validation prototype of the distal part (2/2)
• Video : 3 d.o.f. movement
prototype with articulated gripper
prototype with compliant gripper
• Performances
Pitch articulation (without external loading : 90°)
With load of 157 grams applied at 25 mm of the articulation
Distal roll transmission (initial pitch art. : 90°)
With torque of 98 g х 5 mm (together with a torque due to
98 g applied at 25 mm of the pitch articulation)
Compliant gripper (hydraulic muscle actuated)
Gripping force of 19 g mini. (together with a torque due to
19 g applied at 25 mm of the pitch articulation)
Articulated gripper (hydraulic muscle actuated)
Gripping force of 140 g mini. (together with a torque due to
140 g applied at 25 mm of the pitch articulation)
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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A new dexterous robotized instrument tip for mini-invasive surgery, based on flexible mechanisms and miniature hydraulic actuation
Conclusion and perspectives
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Conclusion
the new technologies proposed allowed to obtain a prototype
that showed …
compatibility with a 5 mm diameter insertion trocar
good dexterity, needed e.g. for laparoscopic suturing task
no mechanical coupling of the intracorporeal degrees of freedom
the first results obtained are encouraging, as they prove the
feasibility of new high d.o.f. MIS or exploration robotized
instruments and devices, even if
compliant pitch articulation and gripper showed a limited rigidity (to be
improved)
depending on the actuation stroke need (i.e. on the compliant
articulation to control), the miniature hydraulic muscle longitudinal
encumbrance should be reduced
external motorization unit volume and mass could be further reduced
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Perspectives
these new technologies are being deeper studied in the
framework of an ITEA 2 project, with application to robotics
for SILS (Single Input Laparoscopic Surgery)
… and relative technologies could also address future
research projects (towards N.O.T.E.S. ?)
EU-Robotics Forum - Workshop on Surgical Robotics - Vasteras, Sweden, 6-8 April, 2011
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