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Fix refgain controllers with integral action #1222

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Fix refgain controllers with integral action #1222

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2 changes: 1 addition & 1 deletion control/statefbk.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1006,7 +1006,7 @@ def _control_output(t, states, inputs, params):
A_lqr = np.eye(C.shape[0])
B_lqr = np.hstack([-np.eye(C.shape[0], sys_ninputs), C])
C_lqr = -K[:, sys_nstates:] # integral gain (opt)
D_lqr = np.hstack([Kf, -K])
D_lqr = np.hstack([Kf, -K[:, :sys_nstates]])

ctrl = ss(
A_lqr, B_lqr, C_lqr, D_lqr, dt=sys.dt, name=name,
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33 changes: 33 additions & 0 deletions control/tests/statefbk_test.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1233,6 +1233,39 @@ def test_refgain_pattern(ninputs, Kf):
np.testing.assert_almost_equal(clsys.D[:sys.nstates, :], manual.D)


def test_refgain_pattern_integral_action():
sys = ct.ss(
[[0.0, 1.0], [-2.0, -3.0]],
[[0.0, 1.0], [1.0, 0.0]],
np.eye(2),
np.zeros((2, 2)),
)
Kp = np.array([[1.0, 2.0], [3.0, 4.0]])
Ki = np.array([[5.0], [6.0]])
K = np.hstack([Kp, Ki])
Kf = np.diag([7.0, 8.0])
C_int = np.array([[1.0, 0.0]])

ctrl, clsys = ct.create_statefbk_iosystem(
sys, K, Kf, integral_action=C_int, feedfwd_pattern='refgain')

np.testing.assert_array_equal(ctrl.A, np.zeros((1, 1)))
np.testing.assert_array_equal(ctrl.B, np.hstack([-np.eye(1, 2), C_int]))
np.testing.assert_array_equal(ctrl.C, -Ki)
np.testing.assert_array_equal(ctrl.D, np.hstack([Kf, -Kp]))

np.testing.assert_array_equal(
clsys.A, np.block([[sys.A - sys.B @ Kp, -sys.B @ Ki],
[C_int, np.zeros((1, 1))]]))
np.testing.assert_array_equal(
clsys.B, np.vstack([sys.B @ Kf, -np.eye(1, sys.ninputs)]))
np.testing.assert_array_equal(
clsys.C, np.block([[np.eye(sys.nstates), np.zeros((sys.nstates, 1))],
[-Kp, -Ki]]))
np.testing.assert_array_equal(
clsys.D, np.vstack([np.zeros((sys.nstates, sys.ninputs)), Kf]))


def test_create_statefbk_errors():
sys = ct.rss(2, 2, 1, strictly_proper=True)
sys.C = np.eye(2)
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