Changing shape and stiffness Applications of soft stiffness - - PowerPoint PPT Presentation

UCL Mechanical Engineering UCL Robotics

Changing shape and stiffness

Applications of soft stiffness controllable robots Dr Helge Wurdemann Lecturer in Medical Devices

Current Surgical Robotic Systems

Image source: www.dezeen.com - The Miro Surge system

da Vinci Surgical Robot

ALF-X Surgical Robotic System by TransEnterix

Raven – An open source robot-assisted surgical system

German Aerospace Center

FRK – Robin Heart PVA

Dexterity constraints of rigid-link robots

• It can be problematic to change surgical targets inside the abdomen, and

when needed to work in different anatomical districts, it can become necessary to move the entire robotic trolley.

• Difficulties with the positioning of current camera systems often lead to a

suboptimal visualization of the field ‐ surgical manoeuvres may be influenced.

• Usually additional support is required by a laparoscopic assistant at the

patient’s side.

• The current da Vinci robotic system does not provide the surgeon with

haptic feedback of the handled tissues. This, added to the strong mechanical power of the robotic arms, can lead to tissue tears.

• What about soft systems? Or even soft-stiff systems?

#SoftHapticsLab

Soft, stiffness- controllable robots Soft tissue sensing Haptic devices Pseudo haptics Research at the #SoftHapticsLab

January 2012 to December 2015 Coordinator: Professor Kaspar Althoefer Queen Mary University of London Technical and project manager: Dr Helge Wurdemann

STIFFness controllable Flexible and Learnable manipulator for surgical OPerations

The STIFF-FLOP consortium

Scientific Experts from Biology Scientific Experts from Medicine Scientific Experts from Engineering

Total Mesorectal Excision (TME)

based on presentation by Prof Alberto Arezzo, University of Turin

Total Mesorectal Excision (TME)

based on presentation by Prof Alberto Arezzo, University of Turin

’ PO

A number of access points fairly wide-spread across the abdomen are needed. Employing da Vinci requires frequent repositioning of overall system as well as human assistance near the patient.

Procedure Elements (TME):

• Mobilization of Splenic Flexure
• Mobilization of Sigmoid Colon / Toldt Fascia
• Incision of Pelvic Peritoneum
• Ligation of Inferior Mesentric Artery (IMA)
• Mobilization of Left Colon / Gerota Fascia
• Ligation of Mesentric Vein
• Posterior TME
• Lateral TME
• Posterior TME (2)
• Anterior TME (Male/Female)
• Section of Rectum
• Anastomosis

Posterior TME

Soft, Stiffness-controllable Robots

Image source: DKFindout.com

STIFF-FLOP Manipulator Design

Distal joint Omni-directional bending Stiffening system Actuation

CURRENT DIMENSIONS

• Silicone Unit: 0030 EcoFlex
• Sheath: PET
• Stiffening chamber membrane: Latex
• Granular matter: Coarse Coffee

MATERIALS OVERALL STRUCTURE 3 chambers for fluidic Actuation Stiffening

STIFF-FLOP Manipulator Design

Granular jamming mechanism for stiffness control

Granular jamming mechanism for stiffness control

Granular jamming mechanism for stiffness control

• I. De Falco, Y. Noh, H.A. Wurdemann, K. Althoefer, M. Cianchetti, A. Menciassi, submitted to

Smart Material and Structures, 2016.

Challenges

• Actuation/sensor interference

(drastically changes the reading!).

• Chamber cross-section area changes

(nonlinear actuation).

• Chamber geometrical centers

shifted inwards

• Resulting bending moment smaller.

Flexible and High Dexterous 2-module Soft Robot

Flexible and High Dexterous 2-module Soft Robot

• A. Arezzo et al., Total Mesorectal Excision using a soft and flexible robotic arm: a feasibility study

in cadaver models, Surgical Endoscopy, 2016.

Air Compressor Motors Input device

Push & Pull Antagonistic System

Pressurised Air (pushing) Tendons (pulling)

Section A : A

Fabric Sleeve Latex Bladder A A

Pressurised Chamber 1 [bar]

Internal Pressure Sleeve Reaction Force Ambient Pressure

Antagonistic actuation principle

• A. Stilli, H.A. Wurdemann, K. Althoefer, IEEE/RSJ IROS, 2014.
• F. Maghooa, A. Stilli, K. Althoefer, H.A. Wurdemann, IEEE ICRA, 2015.

• A. Stilli, H.A. Wurdemann, K. Althoefer, IEEE/RSJ IROS, 2014.
• F. Maghooa, A. Stilli, K. Althoefer, H.A. Wurdemann, IEEE ICRA, 2015.

Antagonistic actuation principle

• A. Shiva, A. Stilli, Y. Noh, A. Faragasso, I. De Falco, G. Gerboni, M. Cianchetti, A. Menciassi, K.

Althoefer, H.A. Wurdemann, IEEE RA-L, 2016.

Antagonistic actuation principle

FourbyThree

• A. Stilli, K. Althoefer, H.A. Wurdemann, Soft Robotics, 2016.

Variable stiffness link

• A. Stilli, K. Althoefer, H.A. Wurdemann, Soft Robotics, 2016.

Variable stiffness link

Image source: MIRAISENS Inc.

Innovative Haptic Technology

• M. Li, J. Konstantinova, A. Jiang, H. Liu, T. Nanayakkara, L.D. Seneviratne, P. Dasgupta, G. Mehra, K. Althoefer,

H.A. Wurdemann, Medical & Biological Engineering & Computing, 2015.

Surgeon Patient

Slave robot Master console No sense

• f touch

Image source: Intuitive Surgical

Haptics of RMIS

Master side

Slave side

M Li, T. Ranzani, S. Sareh, L.D. Seneviratne, P. Dasgupta, H.A. Wurdemann, K. Althoefer, Smart Materials and Structures, 2014 – “Highlights of 2014”

Innovative Haptic Technology

Concept Design

Innovative Haptic Technology - Design

Methodology:

• Combination of pneumatic air actuation

and granular jamming.

• coffee powder inside a latex membrane

→ low hysteresis, high stiffness

M Li, T. Ranzani, S. Sareh, L.D. Seneviratne, P. Dasgupta, H.A. Wurdemann, K. Althoefer, Smart Materials and Structures, 2014 – “Highlights of 2014”

FE-Modelling

Innovative Haptic Technology - Analysis

Experimental analysis

M Li, T. Ranzani, S. Sareh, L.D. Seneviratne, P. Dasgupta, H.A. Wurdemann, K. Althoefer, Smart Materials and Structures, 2014 – “Highlights of 2014”

Innovative Haptic Technology - Results

• Sensitivity Se: a measure of the test's ability to identify positive results.
• Specificity Sp: a measure of the test’s ability to correctly identify negative

results.

• Positive predictive value PPV: the proportions of positive results that are true

positive results.

• Accuracy ACC

Soft Haptic Screen

Soft Haptic Screen

Thanks to

Thanks. Dr Helge Wurdemann @h_wurdemann softhaptics.website h.wurdemann@ucl.ac.uk Thank you.