Integration of Force Reflection with TactileSensing for Minimally InvasiveRobotics-Assisted Tumor Localization

PRESENTED BY, BINIL P JOY S7 AEI SJCET, PALAI

Introduction

TUMOR localization - preoperatively or intraoperative.

Robotics-Assisted Minimally Invasive Surgery (RAMIS)

Force feedback

Tactile feedback

Tactile sensors -capacitive elements , strain gauges or piezoelectric ceramics .

Three haptic feedback modalities: Direct Force Feedback(DFF), visual presentation of force feedback (VPFF), and visual presentation of tactile feedback (VPTF).

SETUP DESCRIPTION

Mitsubishi PA10-7C robot

Tactile Sensor Specifications:

* (15 X 4)array of pressure sensing capacitive elements

* Sensor size - 30 mm X 8 mm

The real-time sapphire acquisition and visualization software

6-DOF ATI Gamma force sensors

Sensors - Wrist force sensor & Environment force sensor.

User Datagram protocol & QuaRC real-time software. .

Palpation probe (TSI)

Master-slave robotic setup for palpating a bovine liver.

FORCE FEEDBACK FOR TUMOR LOCALIZATION

Force on tissue plane

Optimal Exploration force

Stiffness of the tissue and the size and the depth of tumor

Avoid any damage to the tissue.

Position and force frames in a palpation task along with the slaveworld frame.

MASTER-SLAVE CONTROL DESIGN

Wrist force sensor that generates a force Fe.

Jacobian transpose impedance control (JT-IC)

Disturbance force observer

A scaling factor of one was chosen for the translational motion

A factor of 0.25 was chosen for the palpation force

Position accuracy 0.1 mm, deadband 0.2 mm, and time delay 46 ms

C1

C2

JT-IC CONTROL SCHEME AT MASTER

SIDE

Position control

BLOCK DIAGRAM

Fe

HAPTIC INTERFACE

PA 10-7C

Force Observer

VelocityObserver

EXPERIMENTAL CONDITIONS Tissue Models

I. The tissue used for the experiments was ex vivo bovine

II. Liver Tumors - artificial hemispheres made from thermoplastic adhesive (hot-melt glue)

Pilot Study and Methods

I. Using force feedback by either direct or visual form, the operator is able to detect only large tumors.

II. Inadequate control of the depth of palpation during tumor localization.

III. Effectiveness of force feedback in robotics-assisted tactile sensing:

1) VPTF.

2) VPTF along with DFF to the operator’s hand(VPTF + DFF) .

3) Visual presentation of both tactile feedback and force feedback (VPTF + VPFF)

Multisubject Study Conditions 8 Subjects were chosen.

Average stiffness of sample = 1,448 N/m.

Performance Assessment Criteria A true-positive test occurs when the tumor is correctly identified and found in the

tissue.

A false-positive test occurs when the user indicates that a tumor is found where none is located in that area.

A false-negative test occurs when the user does not find the tumor located in the tissue.

A true-negative test occurs when the user correctly identifies that there is no tumor located in the tissue

EXPERIMENTAL RESULTS

VPTF+DFF-Both tumors Detected with accuracy of 1.29 mm and 0.80 mm.

VPTF+VPFF- Both tumors Detected with accuracy of 2.9 mm and 3.46 mm.

A statistical analysis was made on the results of ninety six trials obtained from the eight subjects.

DISCUSSIONo Case 1

No control of the forces applied to the tissue in the case of tactile feedback alone

The subjects detected false positives using tactile feedback

o Case 2

Lateral forces and the force in the palpation direction were reflected to the operator’s hand.

o Case 3

Visual force feedback + visual tactile feedback 

Accurate for large tumors

50 percent increase in tumor localization accuracy,

8 percent increase in sensitivity,

55 percent decrease in maximum force applied

22 percent longer task completion time

Limitations

The accuracy of the interaction force measurement at the tip of the instrument.

The lack of an actuated wrist at the tip of the instrument.

Conclusion

Better control of the forces in the specified ranges

Enough exploration force was applied to the tissue while avoiding damage to it.

The accuracy of tumor localization increased 50 percent

References

• IEEE TRANSACTIONS ON HAPTICS, VOL 6,NO.2 APRIL-JUNE 2013

THANKS