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Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

ACTIVE WRISTS ENDOSCOPE NAVIGATIONIN ROBOTIZED LAPAROSCOPIC SURGERY

Enrique Bauzano Núñez, Dr. Víctor Muñoz MartínezDra. Isabel García Morales, Belén Estebanez Campos

Dpto. Ingeniería de Sistemas y Automáticahttp://www.isa.uma.es

Universidad de Málaga (Spain)

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Enrique Bauzano Nuñez ebauzano@uma.es

Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

OUTLINE

I. Introduction

II. Laparoscopic Navigation on Active Wrists

III.Force Interaction Model

IV.Control Strategy

V. Implantation and Experiments

VI.Conclusions and Future Works

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Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

I. INTRODUCTION

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I. Introduction

Laparoscopic Surgery: “Accessing to the abdominal cavity with especial long instruments.”

LAPAROSCOPIC SURGERY

Advantages Lessen recovery time

Limit post-operative complications

Lower scars

Constraints Movement limitations

Loss of touch and 3D perception

Hand-eye coordination problems

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I. Introduction

Proposal: “Solve the motion problem for a laparoscopic surgery robot assistant with an actuated wrist.”

GLOBE-SHAPED MOVEMENTS

{I} Fulcrum point Orientation angle Altitude angle External distance

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ROBOTIC WRISTS COMPARATIVE

• Null forces on abdomen• Precision depends on fulcrum accuracy

• Null forces on abdomen• Special instruments needed• Previous calibration• Voluminous mechanisms

• No additional mechanisms on wrist• No special instruments needed• Low volume• May apply forces on abdomen

I. Introduction

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Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

II. LAPAROSCOPIC NAVIGATIONON ACTIVE WRISTS

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NAVIGATION PROBLEM

I

XI

ZI

CC

e

AB

es

Navigation Problem: Move the endoscope from A to B an altitude angle .

I0

I0 Initial fulcrum (desired)

I Actual fulcrum

C Estimated fulcrum

e External distance error

es Separation error

II. Laparoscopic Navigation on Active Wrists

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ERROR ANALYSIS

Separation Error: When estimated fulcrum C differs from real location I0, external distance error e forces a fulcrum displacement es over the abdomen, which can be geometrically analyzed.

0 10 20 30 40 50 60 70 80 90

5

10

15

20

25

30

35

40

45

50

Altitude (degrees)

Sep

arat

ion

Erro

r es (m

m)

es = e' tan

50

25

10

e' = 5 tanees

II. Laparoscopic Navigation on Active Wrists

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Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

III. FORCE INTERACTION MODEL

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ENDOSCOPE-ABDOMEN INTERACTION MODEL

XI

ZI

Fr

III. Force Interaction Model

rs FFgF m

A

Cmg

I0

Fs

I

B

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FORCES MODEL

Stiffness Coefficient

0 0.5 1 1.5-3

-2

-1

0

1

2

3

4

Time (seconds)

Ela

stic

ity

(N/m

m)

Real Estimated

-20

0

20

00.5

11.5

2

0

2

4

6

8

10

Altitude (degrees)Time (seconds)

Fric

tion

F r (New

ton)

ss eF NFr

III. Force Interaction Model

Friction Coefficient

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Enrique Bauzano Nuñez ebauzano@uma.es

Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

IV. CONTROL STRATEGY

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NAVIGATION STRATEGY

1. Rotate around estimated fulcrumFulcrum displacement over the abdomen

2. Passive Wrist BehaviorEndoscope rotation over the wrist to reduce fulcrum displacement

3. Altitude angle correctionRecover desired altitude angle

I

L1L3

XI

ZI

C

IV. Control Strategy

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PASSIVE WRIST BEHAVIOR (I)IV. Control Strategy

Planner Robot

Abdomen Interaction

Force Sensor

Separation estimator

External Distance estimator

KFriction + Weight

Filtering

Cor

rect

ion

Ang

le

Planned Movement

Followed Altitude

Abdomen Force Fs Force F

Planned Altitude p

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PASSIVE WRIST BEHAVIOR (II)IV. Control Strategy

Planner– Calculates the required trajectory with a first order system behavior– Acts faster than correction angle loop

Robot: Performs the controlled movement

Endoscope-Abdomen Interaction: Generates abdominal forces

Force Sensor: Measurement of forces

Separation Estimator– Depends on the stiffness estimation– Its value remains the same if Fs < Fthreshold

External Distance Estimator– Result of Force-Torque balance– Its value remains the same if Fs < Fthreshold

rT

sT

s LekLekL )1()()1(

e

ssFe

Ce

sρ

s

FuM

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SPHERICAL CONTROL LOOPIV. Control Strategy

Passive Wrist Behavior Robot

Followed Altitude

Control PI

+-

Desired Altitude d

Planned Altitude p

Controlled Altitude c

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Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

V. IMPLANTATION AND EXPERIMENTS

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IMPLANTATION (I)V. Implantation and Experiments

Movement Command

Virtual-PA10 simulator (Matlab)

Matlab-C++ DLL Library

linker

C++ Library PA-10 ControllerPA-10 Robot

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IMPLANTATION (II)V. Implantation and Experiments

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EXPERIMENTAL RESULTS

0 2 4 6 8 100

0.5

1

1.5

2

2.5

3

3.5

Time (seconds)

Sepa

ratio

n Er

ror e

S (mm

)

V. Implantation and Experiments

0 2 4 6 8 10266

268

270

272

274

276

278

Time (seconds)

Exte

rnal

Dist

ance

e (

mm

)

EstimatedReal

0 1 2 3 4 5 6-49

-48

-47

-46

-45

-44

-43

-42

-41

-40

Time (seconds)

Alti

tude

(d

egre

es)

Desired Followed

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Enrique Bauzano Nuñez ebauzano@uma.es

Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

VI. CONCLUSIONS AND FUTURE WORKS

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Enrique Bauzano Nuñez ebauzano@uma.es

Active Wrists Endoscope Navigation in Robotized Laparoscopic Surgery

FUTURE WORKS

Active tasks during an intervention

Development of semi-autonomous robotic surgeon assistants

Like remote-centered wrists, useful on tele-surgery fields

CURRENT STATUS

System does not depend on friction force

Stiffness can be now measured on-line, not model needed