|
FAQ (Frequently Asked Questions)
Category:
CDS 101/110 Fall 2003
Identifiers: FN H0 H1 H2 H3 H4 H5 H6 H7 H8 L0.0 L1.1 L1.2 L10.1 L2.1 L2.2 L3.1 L3.2 L4.1 L4.2 L5.1 L5.2 L6.2 L8.1 L9.1 L9.2
-
In Problem #1, how do we describe the dynamics of these blocks?
Submitted by: mreiser
Submitted on: October 6, 2003
Identifier:
H2
We are looking for concise but descriptive explanations of the dynamics. We don't want you to generate equations, because they are plainly listed in the paper. So a brief discussion of what the equations governing the dynamics are and where they came from, is adequate. It is important to be very clear about the states of each block, and then to discuss the role of the dynamics in updating these states.
For the blocks with no dynamics, there is still some mapping from inputs to outputs, though this occurs in a 'memory-less' way, that is no state variables are needed as 'memory' quantities, we can immediately determine the outputs of the block from the current inputs.
Please keep in mind that we are asking for the descriptions of the inputs, output, states, and dynamics of the model in the paper, and not of the real system (flying insect) that has been modeled.
[Back to Top]
-
Where/when do we get graded homeworks back?
Submitted by: murray
Submitted on: October 6, 2003
Identifier:
L2.1
, H0
, H1
, H2
Graded homework will be handed back one week after they are turned in. When possible, we will put them out on the table outside 74 Jorgensen before lecture. After that, they will be available outside 109 Steele.
[Back to Top]
-
In Problem 4, should we write the system dynamics in state space form or as just sets of ODEs?
Submitted by: mreiser
Submitted on: October 8, 2003
Identifier:
H2
For this homework set, and all in thr future, you are heavily encouraged to convert all systems of ODEs into the convenient state space form. Many system properties we will care about are easily evaluated given the state space form, and it allows for easy implementation in Matlab.
[Back to Top]
-
In problem 4c, what if we don't get a diagonal matrix?
Submitted by: mreiser
Submitted on: October 8, 2003
Identifier:
H2
This is fine, you will in fact only get a matrix that is block diagonal in form. So if you're state space vector is [z1 z1dot z2 z2dot]', you should get a system of ODEs where the z1 terms are not dependent on the z2 terms. This is not as easy to solve as a diagonal marix, but you should still be able to solve these 2 ODEs.
[Back to Top]
-
From the fly paper, what is quasi-steady model?
Submitted by: mreiser
Submitted on: October 9, 2003
Identifier:
H2
"quasi-steady" is a term that gets used frequently to describe a type of model (typically used to describe fluid mechanics problems), where steady-state measurements are applied to an un-steady system. For example, suppose force is related to the velocity of an object through the fluid. The force produced by the object moving through the fluid can be measured at difference velocities, and these measured (steady-state) forces can be fit with some parametric model. The quasi-steady assumption then applies this empirical model to the instantaneous velocities of the object to predict the forces. This ignores all transient effect, and is not always a successful approximation. But these techniques have been applied very successfully to insect flight aerodynamic models.
[Back to Top]
-
Here are some clarifications regarding homework #2.
Submitted by: lars
Submitted on: October 10, 2003
Identifier:
H2
For HW#2, 2(d) wants the response of the closed loop system (like in (c),
but with the hill disturbance added).
In 4(a-b), it doesn't matter whether you write "u(t)" or "sin(wt)". You
should solve 4(c) with sin(wt) as input and solve explicitly for the
particular solution in terms of the initial conditions x_0 and dot{x_0}.
It's fine to let the initial conditions both be zero in 4(d).
[Back to Top]
-
More clarifications on homework #2.
Submitted by: lars
Submitted on: October 12, 2003
Identifier:
H2
Note that you need to make sure the units are consistent between the step input and the vehicle and engine models in problem #2. This may include converting the step input from [mph] to SI units [m/s].
In 2(c), the gains given are different than the default gains that were in the model from HW#1. Use the gains given in the problem set. (Though we won't take off points if you use the default ones, it's easier if everyone does the same thing).
What is a closed form expression? From Mathworld (http://mathworld.wolfram.com), an equation is said to be a closed-form solution if it solves a given problem in terms of functions and mathematical operations from a given generally accepted set. For this problem, we mean that the solution should be in terms of just the initial condition and the step number (k).
[Back to Top]
|