Inputs

sys1, …, sysN

LTI models to be connected by named-based connection. The properties ’inname’ and ’outname’ of each model should be set according to the desired input-output connections.

sys

LTI model where the outputs are connected to the inputs by index-based connection.

in

For name-based interconnections, string or cell of strings containing the names of the inputs to be kept. The names must be part of the properties ’ingroup’ or ’inname’. For index-based interconnections, vector containing the indices of the inputs to be kept.

out

For name-based interconnections, string or cell of strings containing the names of the outputs to be kept. The names must be part of the properties ’outgroup’ or ’outname’. For index-based interconnections, vector containing the indices of the outputs to be kept.

cm

Connection matrix (not name-based). Each row of the matrix represents a summing junction. The first column holds the indices of the inputs to be summed with outputs of the subsequent columns. The output indices can be negative, if the output is to be substracted, or zero. For example, the row

[2 0 3 -4 0]

or

[2 -4 3]

will sum input u(2) with outputs y(3) and y(4) as

u(2) + y(3) - y(4).

If several systems are cinnected as in the name-based case, they have to be stacked by append before using connect.

Outputs

csys

Resulting interconnected system with outputs out and inputs in.

Example

Consider the control loop with reference r, disturbances d1, d2 and an additional output which represents the output of the controller

                       d1 --+              d2 --+
                            |                   |
          e  +--------+     v  u  +--------+    v
 r --->o---->|  K(s)  |--+->o---->|  G(s)  |--->o--+----> y
       ^ -   +--------+  |        +--------+       |
       |                 |                         |
       |                 +------------------------------> yc
       |                                           |
       +-------------------------------------------+

Name-based interconnections:

 G.inname = 'u';
 G.outname = 'y1';
 K.inname = 'e';
 K.outname = 'yc';
 s1 = sumblk ('e = r - y');
 s2 = sumblk ('u = yc + d1');
 s3 = sumblk ('y = y1 + d2');
 in = {'r', 'd1', 'd2'};
 out = {'y', 'yc'};
 G_cl1 = tf (connect (K, G, s1, s2, s3, in, out))

Index-based interconnections (without changing G and K):

 G1 = tf (1);   # static gains with r, d1, d2, y as outputs
 G_all = append (G1, G1, G1, K, G, G1);
 cm = [4, 1, -6; 5, 4, 2; 6, 5, 3];
 in = [1, 2, 3];
 out = [6, 4];
 G_cl2 = connect (G_all, cm, in, out)

Index-based interconnections (changing G and K):

 [A,B,C,D] = ssdata(K);
 K = ss (A, [B -B], C, [D -D]);     # compare s1 above
 [A,B,C,D] = ssdata(G);
 G = ss (A, [B B 0*B], C, [D D 1]); # compare s2 and s3 above
 G_all = append (K, G);
 cm = [2, 2; 3, 1];
 in = [1, 3, 5];
 out = [2, 1];
 G_cl3 = tf (connect (G_all, cm, in, out))

See also: sumblk, append

Source Code: @lti/connect