Merge pull request #285 from bnavigator/timeresp-fix

murrayrm · web-flow · commit 00962cf8d433 · 2019-04-06T19:03:14.000-07:00
Fix forced response simulation of discrete time system
diff --git a/control/tests/timeresp_test.py b/control/tests/timeresp_test.py
@@ -193,6 +193,16 @@ def test_forced_response(self):
                               42.3227, 44.9694, 47.1599, 48.9776]])
         _t, yout, _xout = forced_response(self.mimo_ss1, t, u, x0)
         np.testing.assert_array_almost_equal(yout, youttrue, decimal=4)
+        
+        # Test discrete MIMO system to use correct convention for input
+        sysc = self.mimo_ss1
+        dt=t[1]-t[0]
+        sysd = c2d(sysc, dt)           # discrete time system
+        Tc, youtc, _xoutc = forced_response(sysc, t, u, x0)
+        Td, youtd, _xoutd = forced_response(sysd, t, u, x0)
+        np.testing.assert_array_equal(Tc.shape, Td.shape)
+        np.testing.assert_array_equal(youtc.shape, youtd.shape)
+        np.testing.assert_array_almost_equal(youtc, youtd, decimal=4)
 
     def test_lsim_double_integrator(self):
         # Note: scipy.signal.lsim fails if A is not invertible
diff --git a/control/timeresp.py b/control/timeresp.py
@@ -322,7 +322,8 @@ def forced_response(sys, T=None, U=0., X0=0., transpose=False):
     else:
         # Discrete time simulation using signal processing toolbox
         dsys = (A, B, C, D, sys.dt)
-        tout, yout, xout = sp.signal.dlsim(dsys, U, T, X0)
+        # Transpose the input to match toolbox convention 
+        tout, yout, xout = sp.signal.dlsim(dsys, np.transpose(U), T, X0)
 
         # Transpose the output and state vectors to match local convention
         xout = sp.transpose(xout)
