teleoperation Flashcards
Explain the teleoperated robot assisted minimally invasive surgery
starts with surgeon who is in control of a master console which is linked to the patient side robot, which is assisted by instruments and cameras to carry out actions. The end the patient is operated on
there is always feedback to the master console
What is motion scaling?
Translates natural, macro surgeon movements to nano wrist micro instruments
Scaling down the movement of a robot in comparison to the surgeons movements
Why is tremor reduction important in medical robotics?
It enables precise movements that can reduce errors and vessel trauma during suturing
reduces surgery time
What was the first teleoperated system and what did it do
A Polygraph is a device that
produces a copy of a piece of writing simultaneously with the creation of the original, using pens and ink.
Famously used by Thomas Jefferson ~1805.
Typically uses a pantograph mechanism: a five-bar linkage
with parallel bars such that motion at one point is
reproduced at another point
Explain the history of teleoperations
First teleoperated Manipulator: 1948, Ray Goertz, U.S. Atomic Energy Commission
Goal: protection of workers from radiation, while
enabling precise manipulation of materials
a device which is responsive to another device is termed a “slave”/“follower” and the controlling device is
termed a “master”
At first, mechanical linkages and cables
– 1954: electrical and hydraulic
servomechanisms
– 1960s: Closed circuit television and HMDs
What is bilateral control
inherent in “mechanical”
teleoperators
forces at the follower endeffector are reflected to the
master end-effector
displacements produced at the
follower end-effector produce
a displacement at the master
end-effector
There is feedback coming from the slaver end effector back to the main console.
What types of feedback are there?
force feedback
haptic feedback
kinematic feedback
acceleration feedback
vibration feedback
combinations
Give more applications of teleoperated robots that are not in the field of medicine
Undersea: exploration and oil
acquisition Space
1967: Surveyor III landed on the surface of the Moon (a few
seconds delay in the two-way transmission to earth of commands and information)
1976:Viking spacecraft, landed on Mars was
programmed to carry out strictly automated operations
Shuttle Remote Manipulator System (SRMS):
retrieves satellites and place them in the cargo bay; mobile work platform for astronauts during
space walks
What is a robonaut?
Robot Systems Technology Branch at
NASA’s Johnson Space Center
Purpose: Replace astronauts in dangerous
missions, such as space walk, on the space
shuttle and/or the space station
Both autonomous operation and
teleoperation are being developed
What are the different types of teleoperators and what do they do?
Unilateral teleoperator
- using a PD controller to send info from user to end effector
Bilateral teleoperator
- Has feed back from master to slave and slave to master
- haptic interface feedback
bilateral teleoperator force feedback
- force sensed at end effector is sent back to the user so they can feel the interacting force
bilateral teleoperator using force and acceleration
- if there is changes in acceleration this is fed back to the human
bilateral teleoperator using force and vibration
- vibration can be fed back to the human user
What is a PD controller and show its equation form for a linear control system ?
proportional-derivative controller
This is a proportional-derivative (PD) controller, which attempts to
make the follower (2) follow the master (1) position and velocity
fa2(t) = Kp2(x1 - x2) + Kd2 (.x1 - .x2)
Fa2(t) = follower actuator force
x1 = position of master
x2 =position of follower
Kp2 = follower proportional gain
kd2 = follower derivative gain
Every time the master’s position is recorded, the follower robot
attempts to follow the master using this control law
fa1(t) = 0
fa1(t) - master actuator force
The force applied by the master actuator (if it even exists) is 0
show the equation used for the master robot controller for unilateral teleoperation
fa1(t) = Kp1(x2 - x1) + Kd1(.x2 - .x1)
Fa1(t) = master actuator force
x1 = position of follower
x2 =position of master
Kp2 = follower proportional gain
kd2 = follower derivative gain
every time the follower’s position is recorded, the master robot attempts to
follow the follower using this control law
fa1(t) = fe
fa1(t) - master actuator force
fe - measured environment force
everytime the force between the follower and the environment is
recorded, the master robot outputs this amount of force
Explain impedance control and show its equations
attempts to make the user feel a particular impedance
an assumption often made in analysis/prediction of performance both
the master and follower are ideal impedance-type devices:
- linear - f(t) = mx.. + bx. (dot supposed to be on top of letter)
- no multi-dof coupling
- no nonlinear friction
- no backlash
- infinite mechanical stiffness
What are the two teleoperation performance metrics?
tracking
the ability of the follower to follow the master
transparency
(for bilateral teleoperation only)
Many definitions, but a popular one is whether the mechanical impedance felt by the user is the same as the impedance of the environment
explain force generation signals
- desired force in computer
- signal in the form of volts
- amplifiers that change the voltage or current
- motor force/torque
- using kinematics endeffector force/torque
controller on one end and system dynamics on the other end
a controller computes the desired force e.g. f = kp*(x-xd)
This force and externally applied loads results in robot motion e.g. solve for x in f(t) = mx.. + bx.
