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merging changes from Rane van Paassen - see 2013-05-23 ChangeLog entry for details
2 parents 6cbe9ba + 4418e55 commit 3fbc191

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Lines changed: 940 additions & 154 deletions

‎ChangeLog‎

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@@ -1,3 +1,24 @@
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2013-05-23 Rene van Paassen <rene.vanpaassen@gmail.com>
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* src/margin.py: re-vamped stability_margins function. Now
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uses analytical method for TF and state-space, works on FRD
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objects too, and can optionally return all margins found for
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the analytical method.
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* src/xferfcn.py and src/frdata.py: Now return array result
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for fresp when called with an iterable frequency vector
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* src/xferfcn.py and src/statesp.py: added minreal functions
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* src/bdalg.py: implemented append and connect functions (old
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version, with indexes, not with names)
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* src/matlab.py: added connect, append, minreal
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* src/xferfcn.py and src/statesp.py: added/corrected
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__rmul__. In most cases a gain matrix (np.matrix) may now be
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used in combination with ss or tf systems.
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2012-11-10 Richard Murray <murray@altura.local>
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* src/canonical.py: new module implementing conversions to selected

‎src/bdalg.py‎

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@@ -4,10 +4,12 @@
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Routines in this module:
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append
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series
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parallel
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negate
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feedback
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connect
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"""
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@@ -236,3 +238,97 @@ def feedback(sys1, sys2, sign=-1):
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sys2 = tf._convertToTransferFunction(sys2)
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return sys1.feedback(sys2, sign)
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def append(*sys):
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'''
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Group models by appending their inputs and outputs
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Forms an augmented system model, and appends the inputs and
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outputs together. The system type will be the type of the first
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system given; if you mix state-space systems and gain matrices,
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make sure the gain matrices are not first.
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Parameters.
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-----------
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sys1, sys2, ... sysn: StateSpace or Transferfunction
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LTI systems to combine
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Returns
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-------
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sys: LTI system
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Combined LTI system, with input/output vectors consisting of all
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input/output vectors appended
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Examples
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--------
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>>> sys1 = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
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>>> sys2 = ss("-1.", "1.", "1.", "0.")
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>>> sys = append(sys1, sys2)
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.. todo::
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also implement for transfer function, zpk, etc.
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'''
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s1 = sys[0]
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for s in sys[1:]:
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s1 = s1.append(s)
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return s1
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def connect(sys, Q, inputv, outputv):
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'''
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Index-base interconnection of system
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The system sys is a system typically constructed with append, with
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multiple inputs and outputs. The inputs and outputs are connected
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according to the interconnection matrix Q, and then the final
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inputs and outputs are trimmed according to the inputs and outputs
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listed in inputv and outputv.
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Note: to have this work, inputs and outputs start counting at 1!!!!
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Parameters.
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-----------
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sys: StateSpace Transferfunction
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System to be connected
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Q: 2d array
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Interconnection matrix. First column gives the input to be connected
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second column gives the output to be fed into this input. Negative
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values for the second column mean the feedback is negative, 0 means
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no connection is made
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inputv: 1d array
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list of final external inputs
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outputv: 1d array
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list of final external outputs
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Returns
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-------
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sys: LTI system
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Connected and trimmed LTI system
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Examples
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--------
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>>> sys1 = ss("1. -2; 3. -4", "5.; 7", "6, 8", "9.")
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>>> sys2 = ss("-1.", "1.", "1.", "0.")
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>>> sys = append(sys1, sys2)
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>>> Q = sp.mat([ [ 1, 2], [2, -1] ]) # basically feedback, output 2 in 1
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>>> sysc = connect(sys, Q, [2], [1, 2])
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'''
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# first connect
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K = sp.zeros( (sys.inputs, sys.outputs) )
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for r in sp.array(Q).astype(int):
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inp = r[0]-1
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for outp in r[1:]:
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if outp > 0 and outp <= sys.outputs:
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K[inp,outp-1] = 1.
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elif outp < 0 and -outp >= -sys.outputs:
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K[inp,-outp-1] = -1.
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sys = sys.feedback(sp.matrix(K), sign=1)
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# now trim
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Ytrim = sp.zeros( (len(outputv), sys.outputs) )
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Utrim = sp.zeros( (sys.inputs, len(inputv)) )
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for i,u in enumerate(inputv):
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Utrim[u-1,i] = 1.
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for i,y in enumerate(outputv):
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Ytrim[i,y-1] = 1.
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return sp.matrix(Ytrim)*sys*sp.matrix(Utrim)

‎src/frdata.py‎

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@@ -107,7 +107,7 @@ class FRD(Lti):
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def __init__(self, *args, **kwargs):
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"""Construct a transfer function.
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The default constructor is FRD(w, d), where w is an iterable of
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The default constructor is FRD(d, w), where w is an iterable of
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frequency points, and d is the matching frequency data.
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If d is a single list, 1d array, or tuple, a SISO system description
@@ -142,8 +142,8 @@ def __init__(self, *args, **kwargs):
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# The user provided a response and a freq vector
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self.fresp = array(args[0], dtype=complex)
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if len(self.fresp.shape) == 1:
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self.fresp.reshape(1, 1, len(args[0]))
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self.omega = array(args[1])
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self.fresp = self.fresp.reshape(1, 1, len(args[0]))
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self.omega = array(args[1], dtype=float)
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if len(self.fresp.shape) != 3 or \
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self.fresp.shape[-1] != self.omega.shape[-1] or \
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len(self.omega.shape) != 1:
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if mimo:
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outstr.append("Input %i to output %i:" % (i + 1, j + 1))
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outstr.append('Freq [rad/s] Response ')
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outstr.append('------------ ------------------------')
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outstr.append('------------ ---------------------')
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outstr.extend(
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[ '%12.3f %10.4g + %10.4g' % (w, m, p)
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[ '%12.3f %10.4g%+10.4gj' % (w, m, p)
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for m, p, w in zip(real(self.fresp[j,i,:]), imag(self.fresp[j,i,:]), wt) ])
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"""
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# Preallocate the output.
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out = empty((self.outputs, self.inputs), dtype=complex)
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if getattr(omega, '__iter__', False):
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out = empty((self.outputs, self.inputs, len(omega)), dtype=complex)
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else:
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out = empty((self.outputs, self.inputs), dtype=complex)
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if self.ifunc is None:
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try:
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"Frequency %f not in frequency list, try an interpolating"
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" FRD if you want additional points")
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else:
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for i in range(self.outputs):
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for j in range(self.inputs):
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frraw = splev(omega, self.ifunc[i,j], der=0)
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out[i,j] = frraw[0] + 1.0j*frraw[1]
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if getattr(omega, '__iter__', False):
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for i in range(self.outputs):
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for j in range(self.inputs):
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for k,w in enumerate(omega):
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frraw = splev(w, self.ifunc[i,j], der=0)
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out[i,j,k] = frraw[0] + 1.0j*frraw[1]
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else:
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for i in range(self.outputs):
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for j in range(self.inputs):
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frraw = splev(omega, self.ifunc[i,j], der=0)
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out[i,j] = frraw[0] + 1.0j*frraw[1]
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return out
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# Method for generating the frequency response of the system

‎src/lti.py‎

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timebaseEqual()
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"""
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from numpy import absolute, real
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class Lti:
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"""Lti is a parent class to linear time invariant control (LTI) objects.
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self.outputs = outputs
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self.dt = dt
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def damp(self):
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poles = self.pole()
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wn = absolute(poles)
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Z = -real(poles)/wn
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return wn, Z, poles
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# Test to see if a system is SISO
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def issiso(sys, strict=False):
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if isinstance(sys, (int, float, complex)) and not strict:

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