Feedback command for MIMO systems in MATLAB

2021 1 25
1 个回答
回答已采纳
更新时间：2021 1 26
11 次查看（30 天）

0 个投票

I have a state space model with 12 outputs and 4 inputs. I want to close the loop of 8th output with 3 input. then in outer loop i want to close outer loop for 1 output and 3 input again (Quadrotor Pitch and X position states). I have designed PD controller for both loops which is in feedforward.
states = {'x' 'y' 'z' 'u' 'v' 'w' 'Phi' 'Theta' 'Psi' 'p' 'q' 'r'};
inputs = {'Thrust' 'Roll Torque' 'Pitch Torque' 'Yaw Torque'};
outputs = {'x' 'y' 'z' 'u' 'v' 'w' 'Phi' 'Theta' 'Psi' 'p' 'q' 'r'};
STATE_SPACE_MODEL = ss(A,B,C,D,'statename',states,'inputname',inputs,'outputname',outputs);
Now, I can close the first inner loop this way
Pitch_State=STATE_SPACE_MODEL('Theta','Pitch Torque');
PITCH_CL=feedback(Pitch_State*P_PD,1);
now, i want to close the outer loop that contains 'x' state and have a seperate PD controller. I cant find out how to close the outer loop using feeback command can anyone help me out?

请先登录，再回答此问题。

 采纳的回答

Paul
Paul 2021-1-25

0 个投票

I think this does what you want (assuming negative feedback)
Pitch_State = STATE_SPACE_MODEL({'x';'Theta'},'Pitch Torque')
PITCH_CL = feedback(Pitch_State*P_PDinner,1,2);
PITHC_CL = feedback(PITCH_CL,P_PDOuter,1,1);
PITCH_CL will have one input and two outputs still named 'Pitch Torque' and 'x' / 'Theta' respectively. You'll probably want to rename that input.

6 个评论
显示 4更早的评论 隐藏 4更早的评论

let suppose
N=100;
Pinner_PD=0.15+(0.32*N/(1+(N/s)));
P_outter=0.15+(0.32*N/(1+(N/s)));
and if we run the code below
Pitch_State = STATE_SPACE_MODEL({'x';'Theta'},'Pitch Torque')
PITCH_CL = feedback(Pitch_State*P_PDinner,1,2);
PITHC_CL = feedback(PITCH_CL,P_PDOuter,1,1);
then i get this error
Error using * (line 80)
Model I/O dimensions must agree.
Error in Untitled3 (line 3)
PITCH_CL = feedback(Pitch_State*P_PD,1,2);
Paul
Paul 2021-1-26
编辑：Paul 2021-1-26
Transcription and typo errors on my part:
Pitch_State = STATE_SPACE_MODEL({'x';'Theta'},'Pitch Torque')
PITCH_CL = feedback(Pitch_State*P_PDinner,1,1,2);
PITCH_CL = feedback(PITCH_CL*P_PDOuter,1,1,1);
can you tell me how can i plot the margins/bode of open loop (X outer)?
Paul
Paul 2021-1-26
What have you tried so far?
After you close the inner loop, how would you form the open loop transfer function for the outer loop?
I tried and i obtained the required bode plot

请先登录，再进行评论。

更多回答（0 个）

类别

在 帮助中心 和 File Exchange 中查找有关 Control System Toolbox 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by