我正在努力解决汽车问题。 首先，我有一个汽车问题的原始代码：
# Ampl Car Example
#
# Shows how to convert a minimize final time optimal control problem
# to a format pyomo.dae can handle by removing the time scaling from
# the ContinuousSet.
#
# min tf
# dxdt = 0
# dvdt = a-R*v^2
# x(0)=0; x(tf)=L
# v(0)=0; v(tf)=0
# -3<=a<=1
from pyomo.environ import *
from pyomo.dae import *
m = ConcreteModel()
m.R = Param(initialize=0.001) # Friction factor
m.L = Param(initialize=100.0) # Final position
m.tau = ContinuousSet(initialize=[0.0, 0.80, 1.0]) # Unscaled time
m.time = Var(m.tau) # Scaled time
m.tf = Var()
m.x = Var(m.tau,bounds=(0,None))
m.v = Var(m.tau,bounds=(0,None))
m.a = Var(m.tau, bounds=(-3.0,1.0),initialize=0)
m.dtime = DerivativeVar(m.time)
m.dx = DerivativeVar(m.x)
m.dv = DerivativeVar(m.v)
m.obj = Objective(expr=m.tf)
def _ode1(m,i):
if i == 0 :
return Constraint.Skip
return m.dx[i] == m.tf * m.v[i]
m.ode1 = Constraint(m.tau, rule=_ode1)
def _ode2(m,i):
if i == 0 :
return Constraint.Skip
return m.dv[i] == m.tf*(m.a[i] - m.R*m.v[i]**2)
m.ode2 = Constraint(m.tau, rule=_ode2)
def _ode3(m,i):
if i == 0:
return Constraint.Skip
return m.dtime[i] == m.tf
m.ode3 = Constraint(m.tau, rule=_ode3)
def _init(m):
yield m.x[0] == 0
yield m.x[1] == m.L
yield m.v[0] == 0
yield m.v[1] == 0
yield m.time[0] == 0
m.initcon = ConstraintList(rule=_init)
discretizer = TransformationFactory('dae.collocation')
discretizer.apply_to(m,ncp=1, scheme='LAGRANGE-RADAU')
solver = SolverFactory('ipopt')
solver.solve(m, tee=True)
print("final time = %6.2f" %(value(m.tf)))
现在，我想用班级来表达汽车，然后我可以实例化两辆汽车。 所以我这样写：
from pyomo.environ import *
from pyomo.dae import *
m = ConcreteModel()
class Car():
def __init__(self,friction):
self.friction = friction
self.R = Param(initialize = self.friction) # Friction factor
self.tau = ContinuousSet(bounds=(0, 1)) # Unscaled time
self.time = Var(self.tau) # Scaled time
self.tf = Var()
self.x = Var(self.tau, bounds=(0, None), initialize=0)
self.v = Var(self.tau, bounds=(0, None))
self.a = Var(self.tau, bounds=(-3.0, 1.0), initialize=0)
self.dtime = DerivativeVar(self.time)
self.dx = DerivativeVar(self.x)
self.dv = DerivativeVar(self.v)
def _ode1(m, i):
if i == 0:
return Constraint.Skip
return self.dx[i] == m.tf * self.v[i]
self.ode1 = Constraint(self.tau, rule=_ode1)
def _ode2(m, i):
if i == 0:
return Constraint.Skip
return self.dv[i] == m.tf * (self.a[i] - self.R * self.v[i] ** 2)
self.ode2 = Constraint(self.tau, rule=_ode2)
def _ode3(m, i):
if i == 0:
return Constraint.Skip
return self.dtime[i] == m.tf
self.ode3 = Constraint(self.tau, rule=_ode3)
m.car1 = Car(0.001)
m.obj = Objective(expr=m.car1.tf)
def _init(m):
yield m.car1.x[0] == 0
yield m.car1.x[1] == 100
yield m.car1.v[0] == 0
yield m.car1.v[1] == 0
yield m.car1.time[0] == 0
m.car1.initcon = ConstraintList(rule=_init)
discretizer = TransformationFactory('dae.finite_difference')
discretizer.apply_to(m, nfe=10, scheme='BACKWARD')
solver = SolverFactory('ipopt')
solver.solve(m, tee=True)
print("final time = %6.2f" % (value(m.car1.tf)))
然而，我明白了：
Traceback (most recent call last):
File "D:/pyo/pyomoceshi/ceshi3/car/classcar3.py", line 79, in <module>
solver.solve(m, tee=True)
File "D:\python\m\lib\site-packages\pyomo\opt\base\solvers.py", line 582, in solve
self._presolve(*args, **kwds)
File "D:\python\m\lib\site-packages\pyomo\opt\solver\shellcmd.py", line 196, in _presolve
OptSolver._presolve(self, *args, **kwds)
File "D:\python\m\lib\site-packages\pyomo\opt\base\solvers.py", line 661, in _presolve
**kwds)
File "D:\python\m\lib\site-packages\pyomo\opt\base\solvers.py", line 729, in _convert_problem
**kwds)
File "D:\python\m\lib\site-packages\pyomo\opt\base\convert.py", line 110, in convert_problem
problem_files, symbol_map = converter.apply(*tmp, **tmpkw)
File "D:\python\m\lib\site-packages\pyomo\solvers\plugins\converter\model.py", line 164, in apply
io_options=io_options)
File "D:\python\m\lib\site-packages\pyomo\core\base\block.py", line 1646, in write
io_options)
File "D:\python\m\lib\site-packages\pyomo\repn\plugins\ampl\ampl_.py", line 357, in __call__
include_all_variable_bounds=include_all_variable_bounds)
File "D:\python\m\lib\site-packages\pyomo\repn\plugins\ampl\ampl_.py", line 783, in _print_model_NL
list(self_varID_map[id(var)] for var in ampl_repn._linear_vars),
File "D:\python\m\lib\site-packages\pyomo\repn\plugins\ampl\ampl_.py", line 783, in <genexpr>
list(self_varID_map[id(var)] for var in ampl_repn._linear_vars),
KeyError: 68767416L
我想知道如何解决它或使用其他方式。
答案 0 :(得分：1)
以下是您的脚本的工作版本。我改变了一些东西，以便有一个Car函数返回代表汽车的Pyomo Block而不是Car类。通过拥有一个Car类，你实际上是在尝试创建一个Block的子类并遇到一些与之相关的微妙挑战。您可以查看博文here以获取更多信息。我做的第二个更改是在初始条件的声明中，我将ConstraintList的名称从m.car1.initcon更改为m.car1_initcon。区别在于您是希望ConstraintList存在于car1块还是模型上。在您的代码中，＆＃39; dot＆＃39;在名称中意味着你试图将它放在car1 Block上，但规则中产生的约束与模型相关。我更改了名称以解决这种不一致。
from pyomo.environ import *
from pyomo.dae import *
m = ConcreteModel()
def Car(model, friction):
def construct_car_block(b):
b.R = Param(initialize = friction) # Friction factor
b.tau = ContinuousSet(bounds=(0, 1)) # Unscaled time
b.time = Var(b.tau) # Scaled time
b.tf = Var()
b.x = Var(b.tau, bounds=(0, None), initialize=0)
b.v = Var(b.tau, bounds=(0, None))
b.a = Var(b.tau, bounds=(-3.0, 1.0), initialize=0)
b.dtime = DerivativeVar(b.time)
b.dx = DerivativeVar(b.x)
b.dv = DerivativeVar(b.v)
def _ode1(b, i):
if i == 0:
return Constraint.Skip
return b.dx[i] == b.tf * b.v[i]
b.ode1 = Constraint(b.tau, rule=_ode1)
def _ode2(b, i):
if i == 0:
return Constraint.Skip
return b.dv[i] == b.tf * (b.a[i] - b.R * b.v[i] ** 2)
b.ode2 = Constraint(b.tau, rule=_ode2)
def _ode3(m, i):
if i == 0:
return Constraint.Skip
return b.dtime[i] == b.tf
b.ode3 = Constraint(b.tau, rule=_ode3)
return Block(rule=construct_car_block)
m.car1 = Car(m, friction=0.001)
m.obj = Objective(expr=m.car1.tf)
def _init(m):
yield m.car1.x[0] == 0
yield m.car1.x[1] == 100
yield m.car1.v[0] == 0
yield m.car1.v[1] == 0
yield m.car1.time[0] == 0
m.car1_initcon = ConstraintList(rule=_init)
discretizer = TransformationFactory('dae.finite_difference')
discretizer.apply_to(m, nfe=15, scheme='BACKWARD')
solver = SolverFactory('ipopt')
solver.solve(m, tee=True)
print("final time = %6.2f" % (value(m.car1.tf)))