Converting a simple mass-spring system to state-space model, how?

Join the discussion
Registration is free. Start your own thread to ask a follow-up.
2 replies · 13K views · last reply
cb951303
Messages
16
Reaction score
0

Homework Statement



Hi guys/girls

Professor gave this very simple homework where I need to convert the system below to a state-space model.
Diagram of a mass-spring system: a blue block labelled m sits on a vertical spring labelled k, anchored to a floor, with an upward-pointing coordinate axis labelled x beside it.

The system itself is represented by the equation
Code:
m*x" + k*x = f(t)
Where m = 5 and k = 1. Note that, " (doublequote) is a second-order derivative.
Unfortunately I don't have the background to solve it because I slacked too much :redface:

Homework Equations


State-space model that we use is below:
Equation: x-dot(t) = A x(t) + B u(t), the standard state-space model in vector form.

Equation for the output of a state-space model: y(t) = Cx(t) + Du(t), where y is the output, x the state vector, u the input, and C and D matrices.


Any help&explanation would be appreciated, thank you.

EDIT: Ok, I've just read the rules and apparently I'm not allowed to as for solutions without an attempt to solve it. Since I can't even attempt, may I ask a good place/source to start?
 
Last edited by a moderator:
Physics news on Phys.org
attempt:

Code:
5y" + 0y' + y = u

since my diff. eq. is second order, I should have 2 state variables:
Code:
x1 = y
x2 = y'
so the state space model's matrixes become
Code:
A = [ 0 1 ]   B = [ 0 ]
    [ 1 0 ]       [ 1 ]

C = [ 1 0 ]   D = [ 0 ]

does it look ok?