Identified linear system contribution of input is zero
Hello,
I identified a cont. 3rd order linear system using System Identification Toolbox:
y = Cx + Du + e
dx/dt = Ax + Bu + Ke
Upon inspecting the model (which looked decent to me) I see that the "D" value, which is the contribution of input to system output, is zero.
How can this be? The system describes a DC motor controlled by PWM commands (output is shaft position). Surely the commands sent to the motor should influence the position?
I get the following values:
% A weights (3×3 matrix)
A = [ …
0.0356, -3.4131, -14.9525;
-1.0591, 85.8128, 334.3098;
1.5729, -95.1123, -175.5517;
];
% B weights (3×1 vector)
B = [ …
-0.0019;
0.0403;
-0.0225;
];
% C weights (1×3 vector)
C = [ -5316.9, 24.87, 105.92 ];
% D weight (scalar)
D = 0;
% K weights (3×1 vector)
K = [ …
-0.0025;
-0.0582;
0.0984;
];
% Initial state
x0 = [ …
-0.0458;
0.0099;
-0.0139;
];Hello,
I identified a cont. 3rd order linear system using System Identification Toolbox:
y = Cx + Du + e
dx/dt = Ax + Bu + Ke
Upon inspecting the model (which looked decent to me) I see that the "D" value, which is the contribution of input to system output, is zero.
How can this be? The system describes a DC motor controlled by PWM commands (output is shaft position). Surely the commands sent to the motor should influence the position?
I get the following values:
% A weights (3×3 matrix)
A = [ …
0.0356, -3.4131, -14.9525;
-1.0591, 85.8128, 334.3098;
1.5729, -95.1123, -175.5517;
];
% B weights (3×1 vector)
B = [ …
-0.0019;
0.0403;
-0.0225;
];
% C weights (1×3 vector)
C = [ -5316.9, 24.87, 105.92 ];
% D weight (scalar)
D = 0;
% K weights (3×1 vector)
K = [ …
-0.0025;
-0.0582;
0.0984;
];
% Initial state
x0 = [ …
-0.0458;
0.0099;
-0.0139;
]; Hello,
I identified a cont. 3rd order linear system using System Identification Toolbox:
y = Cx + Du + e
dx/dt = Ax + Bu + Ke
Upon inspecting the model (which looked decent to me) I see that the "D" value, which is the contribution of input to system output, is zero.
How can this be? The system describes a DC motor controlled by PWM commands (output is shaft position). Surely the commands sent to the motor should influence the position?
I get the following values:
% A weights (3×3 matrix)
A = [ …
0.0356, -3.4131, -14.9525;
-1.0591, 85.8128, 334.3098;
1.5729, -95.1123, -175.5517;
];
% B weights (3×1 vector)
B = [ …
-0.0019;
0.0403;
-0.0225;
];
% C weights (1×3 vector)
C = [ -5316.9, 24.87, 105.92 ];
% D weight (scalar)
D = 0;
% K weights (3×1 vector)
K = [ …
-0.0025;
-0.0582;
0.0984;
];
% Initial state
x0 = [ …
-0.0458;
0.0099;
-0.0139;
]; system MATLAB Answers — New Questions