Cooperative Manipulation Flashcards
What is a steady hand robot?
A robot that assists with keeping a stable hand during surgery
Vibration at the tip of instrument is minimal
requires force to push instrument in correct direction
Free in all motion but holds it own weight
The robot can stay within a boundary, robot software shows where the surgeon is cutting it turns from green to white on the system.
soft force feedback
Good for delicate surgeries where precision is paramount
What is the robodoc?
back drivable system which means it can be moved with minimal effort if the power goes out
Made for orthopaedic teleoperated procedures now is moving to intelligence robotic assistance.
Explain the transition from manual to robotic surgery
leap forward in medical technologies
Robotics systems offer tighter integration with advanced information systems which offer real time data and precision
these robots extend the capabilities of surgeons providing more active assistance which enables complex procedures to be carried out with higher accuracies and safety
What is admittance control?
The users applied force measured, and the robot is controlled to move proportionally to that force
How robots respond to human input to ensure there’s a controlled movement in surgical procedures
Enables very slow, steady motions
Is excellent underlying control structure for applying virtual fixtures to guide motions
Can be applied to teleoperated as well as cooperative manipulators
For cooperative manipulation it is best used on a very accurate, non receivables robot
explain the admittance control equation
A typical implementation is:
X. d = Ka f
fa = Kp(xd-x) + kd(x. d-x.)
xd, x. d = desired robot position
fa = actuator force
ka - admittance gain
f = force applied by the user (measured)
fa = actuator force
x,x. = robot position, velocity
kp, kd = proportional and derivative gains
Actuator force is a type of PD controller.
tracking a desired motion, position and velocity, therefore the actuator force is going to be proportional to the error at the position level and proportional to the error at the velocity level
If the system becomes non-linear then a PD controller should not be used
if the non-linearity isn’t high then a PD controller can still be used
What happens when Ka becomes zero?
Xd would equal 0 so the fa equation would have nothing to do with xd therefore there is no control over the actuator force
What is impedance?
impedance is the resistance to motion
so if there is high impedance it would be harder to move it and it would be harder to perturb it
What is impedance control?
Models the relationship between force and motion of robots
Robot tries to mimic a virtual mechanical impedance like a spring or a damper
trying to track or follow the impedance
What is the equation for impedance control?
F(s) = Z(s)X(s)
Z is impedance
X is the displacement or position
What is admittance control?
inverse concept to impedance control
Models the relationship between motion and force
Robot feels the force applied to it and responds with a certain velocity or displacement
defines how the robot should move in accordance to an external force
What is the equation for admittance control?
X(s) = Y(s)F(s)
Y is admittance
F is the force
