Download Background Lecture - IEEE Real World Engineering Projects

Remote Surgical Robotics
Control Systems and Human-Machine Interfacing
What is a remote surgical robot?
Da Vinci Surgical System, Intuitive Surgical, Inc.
What is a remote surgical robot?
The surgical console measures the movements of the surgeon.
What is a remote surgical robot?
The robot replicates the movements of the surgeon at the
operating table.
What is a remote surgical robot?
The movements include the manipulation of surgical
implements.
The use of remote surgical robots is growing
• Over 1400 systems sold as of 2010.
• Used in the treatment of:
Bladder Cancer
Colorectal Cancer
Coronary Artery Disease
Endometriosis
Gynecologic Cancer
Heavy Uterine Bleeding
Kidney Disorders
Kidney Cancer
Mitral Valve Prolapse
Obesity
Prostate Cancer
Throat Cancer
Thyroid Cancer
Uterine Fibroids
Uterine Prolapse
Remote surgical robots has advantages
• Possible tele-operations
• Less direct human contact at operating table (less chance
of breaking sterile field)
• Enables smaller movements
 smaller openings
 less chance of infection
 fast healing times
 more precise surgical techniques
Surgeons control the robot entirely by visual feedback
A high definition video system provides 3D images
Could tactile feedback help? Haptic interface
Tying sutures is a common surgical technique
Does tactile feedback help the surgeon?
“… visual force feedback primarily benefits
novice robot-assisted surgeons, with
diminishing benefits among experienced
surgeons.”
Reiley, CE, et al. Effects of visual force feedback on
robot-assisted surgical task performance. J Thorac
Cardiovasc Surg 2008;135:196-202
“… force feedback is helpful in this blunt
dissection task because the artery is stiffer
than the surrounding tissue.”
Wagner CR, et al. Force feedback in a three-dimensional
ultrasound-guided surgical task. Proc.of the 14th
International Symp. on Haptic Interfaces for Virtual
Environ. and Teleoperator Systems (2006).
Does tactile feedback help the surgeon?
No force-feedback in Da Vinci
Surgical Systems
Prototypes with force-feedback
are on the way (Neuroarm.org)
Problem Statement
A company is investigating whether to add forcefeedback capabilities to their surgical robots.
Specifically, they want a proof of concept demonstration
that a neurosurgeon will be able to accurately identify
the surface of the brain and depth at which puncturing
of tissue by a probe occurs.
Tactile sense augments vision
What is a surgical robot? (really)
Surgeon’s hands
Manipulandum
Position Sensors
Interface
Robotic arms
Robot’s hands
Our prototype surgical robot
Your hand position
Joystick
Joystick Sensors
Interface
Motor servo
Probe position
How do you add force-feedback?
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Motor servo
Force to move probe through
Brain tissue (gelatin)
Force Sensor
Joystick and Joystick sensors
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Force Sensor
Motor servo
Force to move probe through Brain
tissue (gelatin)
Logitech Force 3D Pro Joystick
with USB input (force level) and
output (joystick position)
Interface
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Force Sensor
Motor servo
Force to move probe through Brain
tissue (gelatin)
Cerbot 32mx4 Microprocessor
with USB ports, servo controller,
and analog to digital converter
Motor Servo
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Force Sensor
Motor servo
Force to move probe through Brain
tissue (gelatin)
GWS Servo rotates to an angular
position in proportion to its input
Probe and Brain
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Force Sensor
Motor servo
Force to move probe through Brain
tissue (gelatin)
A blunt probe: 6-32 screw
(imagine how little force a
needle would produce!)
Probe and Brain
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Force Sensor
Motor servo
Force to move probe through Brain
tissue (gelatin)
Brain: gelatin poured into a mold;
sometimes called a “phantom
brain”
Force Sensor
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Force Sensor
Motor servo
Force to move probe through Brain
tissue (gelatin)
Thin film sensor sandwiched
into the linkage between the
servo and probe.
Force Sensor: Force sensing resistor (FSR)
7.62 mm
The sensor has two electrical connections (leads),
and there is an electrical resistance between the
leads.
Force Sensor: FSR
As force is applied to the FSR layer, the conductive protrusions
within the ink make contact with the active area. Resistance
decreases as more force is applied and more contacts are made.
Force Sensor: FSR
Note: there is a “threshold” of ~10 grams before a resistance
change occurs.
How can you change the system?
Your hand position
Joystick capable of generating force
Joystick Sensors
servo position
jgain 
joystick position
Interface
Interface
Motor servo
Force to move probe through
Brain tissue (gelatin)
Force Sensor
How can you change the system?
Your hand position
Joystick capable of generating force
Joystick Sensors
fgain 
joystick force
FSR output (V)
Interface
Interface
Motor servo
Force to move probe through
Brain tissue (gelatin)
Force Sensor
How can you change the system?
Your hand position
Joystick capable of generating force
Joystick Sensors
Interface
Interface
Motor servo
Force Sensor
sensor voltage
sensor sensitivity 
probe force
Force to move probe through
Brain tissue (gelatin)
Overview of concepts explored
(It’s alright if you don’t understand what all of these mean;
You’ll learn!)
1. Sensitivity (resolution) vs range (saturation) tradeoff
2. Varying gain allows you optimize the tradeoff
3. How to measure aspects of human perception?
4. What are human factors and how they influence the
design of human-machine interfaces?
5. What does a phantom brain feel like?
Overview of concepts explored
4. What are human factors and how they influence the
design of human-machine interfaces?
•
Design requires that you meet the desired
specifications: “a neurosurgeon will be able to
accurately identify the surface of the brain and depth
at which puncturing of tissue by a probe occurs”
•
Specifications? The robot must be able to provide
tactile feedback within the human operator’s sensory
capabilities (human factors)
Summary of Activities
Each day is an hour long class
Day #2: Optimizing the joystick position to servo
position gain.
Day #3: Familiarization with and calibrating force
sensor capabilities.
Day #4: Matching force sensor capabilities with
the objectives of the problem.
Day #5: Familiarization with joystick force
feedback capabilities and testing the limits of
human perception.
Summary of Activities
Each day is an hour long class
Day #6: Feel a brain! Probe the gelatin brain and
optimize your ability to perceive the surface of the
brain and puncture depth.
Day #7: Finish any testing and discussion of
results.
Day #8: Wrap up lecture.
Optional: Optimizing the identification of the brain
surface with different probe end geometries.
Group Logistics
• Each group will consist of 3-4 students (assigned
by instructor).
• Groups are encouraged to discuss with each
other groups their solutions to the assignments
within the classroom activities.
• Each group will address a set of homework
problems after each class. The answers (one per
group) are due at the beginning of the next class
period.
• The final assignment is to be done on an
individual basis.