How do I keep f as a variable in a state space model, as f is supposed to be the input variable??

1 次查看（过去 30 天）
Arya Sharma
Arya Sharma 2022-5-4
评论： Paul 2022-5-5
m1=1;
m2=1;
l1=1;
l2=1;
M=5;
g=10;
A_motor=[0,1,0,0,0,0;0,0,(-m1*g)/M,0,(-m2*g/M),0;0,0,0,1,0,0;0,0,(g/l1)-(-m2*g)/(M*l1),0,(-m2*g)/(M*l2),0;0,0,0,0,0,1;0,0,(-m1*g)/(M*l2),0,(g/l2)-(m2*g)/(M*l2),0];
B_motor=[0;f/M;0;-f/(M*l1);0;-f/(M*l2)];
C_motor=[0,1,0,1,0,1];
D_motor=[0];
When I input this as my code I recieve an error stating that f is not defined, however I need to keep f as the input variable.

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2022-5-5
Ran in:
Since ‘f’ is only defined in ‘B_motor’ simply create an anonymous function from it, and then from ‘motor_ss’ (to keep with the existing names).
m1=1;
m2=1;
l1=1;
l2=1;
M=5;
g=10;
A_motor=[0,1,0,0,0,0;0,0,(-m1*g)/M,0,(-m2*g/M),0;0,0,0,1,0,0;0,0,(g/l1)-(-m2*g)/(M*l1),0,(-m2*g)/(M*l2),0;0,0,0,0,0,1;0,0,(-m1*g)/(M*l2),0,(g/l2)-(m2*g)/(M*l2),0];
B_motor= @(f) [0;f/M;0;-f/(M*l1);0;-f/(M*l2)];
C_motor=[0,1,0,1,0,1];
D_motor=[0];
motor_ss = @(f) ss(A_motor, B_motor(f), C_motor, D_motor)
motor_ss = function_handle with value:
@(f)ss(A_motor,B_motor(f),C_motor,D_motor)
figure
step(motor_ss(0.0000001))
figure
step(motor_ss(0.0001))
I considered Create State-Space Model with Both Fixed and Tunable Parameters, however that has the tunable parameters only in the ‘A’ matrix (appropriately), so that would not appear to apply here.
See the documentation section on Anonymous Functions if you are not familiar with them.
.
  1 个评论
Paul
Paul 2022-5-5
Ran in:
Hi Star,
Tunable parameters work fine anywhere in the model
m1=1;
m2=1;
l1=1;
l2=1;
M=5;
g=10;
f = realp('f',0); % default value of 0
A_motor=[0,1,0,0,0,0;0,0,(-m1*g)/M,0,(-m2*g/M),0;0,0,0,1,0,0;0,0,(g/l1)-(-m2*g)/(M*l1),0,(-m2*g)/(M*l2),0;0,0,0,0,0,1;0,0,(-m1*g)/(M*l2),0,(g/l2)-(m2*g)/(M*l2),0];
B_motor=[0;f/M;0;-f/(M*l1);0;-f/(M*l2)];
C_motor=[0,1,0,1,0,1];
D_motor=[0];
sys = ss(A_motor,B_motor,C_motor,D_motor)
sys = Generalized continuous-time state-space model with 1 outputs, 1 inputs, 6 states, and the following blocks: f: Scalar parameter, 3 occurrences. Type "ss(sys)" to see the current value, "get(sys)" to see all properties, and "sys.Blocks" to interact with the blocks.
step(sampleBlock(sys,'f',0.0001));

请先登录，再进行评论。

更多回答（1 个）

Paul
Paul 2022-5-4
Hello Arya,
Assuming that f(t) is the input to the system, it is not included in the B-matrix. Rathe, the B-matrix should be:
B_motor=[0;1/M;0;-1/(M*l1);0;-1/(M*l2)];
and the state space model of the system is:
xdot = A_motor * x + B_motor * f
y = C_motor * x + D_motor * f
If f(t) is not the input to the system, further clarification is needed on what f actually is.

类别

在 Help Center 和 File Exchange 中查找有关 MATLAB 的更多信息

标签

产品

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by