CS545–Introduction to Robotics
Catalogue of Questions for Final Exam
1.
(8 Points) You implemented a PD controller for a robot based on sensor reading ob
tained from position sensors. In the first test run, you notice that there are vibrations
and oscillations in one degreeoffreedom. Give at least 4 possible causes for these
vibrations, and for each cause how you would try to improve the robot performance.
2.
(4 Points) What are the major reasons that make the control of interaction forces
more complicated than normal control without interaction forces? Provide at least 4
issues.
3.
(4 Points) Explain briefly the goal of impedance control of an endeffector.
4.
(8 Points) You need to buy a position sensor for a rotary joint in a robot. You are torn
between a potentiometer and an optical encoder. Give at least two pros and cons for
both the potentiometer and the optical encoder.
5.
(8 Points) You used the linearquadratic regulator (LQR) design in Matlab to obtain
good control gains for the cart pole balancer.
A) In order to calculate the LQR gains, what knowledge about the controlled system
did you need to have (i.e., what are the names of the inputs to the LQR function in
Matlab).
B) How would you instantiate the elements from A) numerically such that you can
use the Matlab lqr function. (keywords are sufficient)
6.
(8 Points) Give the generic control law for a gravity compensation controller for a
rigid body dynamics system, and explain the terms in the control law with key
words. How does this control law differ from an inverse dynamics control law?
7.
(5 Points) Give 3 ideas how you would debug software that needs to run in a very
fast realtime robotic system. Give two classical debugging methods that you are
NOT supposed to use in a realtime control loop.
8.
(6 Points) Robotics can be divided in (at least) two major classes: mobile robotics
(=robots on wheels), and manipulator robotics (robot arms, robot legs, etc.). Give 3
reasons why these two areas largely focus on different research topics.
9.
(8 Points) What are the major 4 conceptual steps in performing a local stability
analysis of a robotic system with a given control law?
10.
(4 Points) What is the difference between Euler Angle and Fixed Angle coordinate
transformations?
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11.
(4 Points) What are the major research problems that remain to be solved before we
can build an autonomous humanoid robot? Give at least 4 points.
12.
(2 Points) Give the Laplace Transform of the function
˙
x
=
sin(
x
)
.
13.
(4 Points) Which elements make a realtime operating system different from a nor
mal UNIX operating system? Give at least two points.
14.
(4 Points) Give a feasible control law for all 7 degreesoffreedom for the honey
sphere task from the lab assignment
including
the gravity compensation element.
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 Spring '08
 Schaal

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