GEKKO中的MPC :错误码‘位置4’解

Question

问题更新

以前，我的模型中的控制变量m.P范围很广，这会导致求解器的故障。在约翰博士的建议下，我尝试了对数标度 of P的目标函数。当错误代码‘位置4’出现新错误时：

*** Error in syntax of function string: Missing opening parenthesis
 
Position: 4                   
 log_p-(log10(p))
    ?

下面是模型和求解器设置的一部分。在模型中，我有控制变量m.log_P，两个多变量m.u_1、m.u_2、其他变量P、Q、D_1和D_2都是状态变量，小写字母都是常量。

m.log_P = m.CV(value = np.log10(P_ini), name = 'log_P')  # log_P for scaling
m.log_P.STATUS = 1    # add log_P to objective function, instead of P
m.log_P.FSTATUS = 1
m.P= m.SV(value = P_ini , name = 'P')   # now original P is treated as a state variable

m.u_1 = m.MV(value=u_0, lb = 0, name = 'u_1')
m.u_2 = m.MV(value=u_0, lb = 0, name = 'u_2')
m.u_1.STATUS = 1
m.u_1.FSTATUS = 1
m.u_2.STATUS = 1
m.u_2.FSTATUS = 1

m.Equations([m.P.dt() == (a-mm-n) * m.P + b * m.Q - k_1 * m.D_1 * m.P - k_2 * m.D_2 * m.P,
             m.Q.dt() == mm*m.P - b*m.Q,
             m.D_1.dt() == m.u_1 - r_1 * m.D_1,
             m.D_2.dt() == m.u_2 - r_2 * m.D_2,
             m.log_P == m.log10(m.P)]) # first 4 equations defined by model. The last equation take logrithmic value of P.

m.options.IMODE = 6
m.options.SOLVER = 3
m.options.CV_TYPE = 2   # l2-norm
m.options.EV_TYPE = 2
m.solver_options = ['linear_solver mumps',\
                    'mu_strategy adaptive']

这里，我将二次误差项设为“”m.options.cv_TYPE=2#l2-范数‘“。

for i in range(len(t)-1):

    ts = [t[i],t[i+1]]
    y = odeint(chemo_model, x0, ts, args = (u_infu1[i],u_infu2[i])) # 'chemo_model' is a model function
    P_cell[i+1] = y[-1][0]
    Q_cell[i+1] = y[-1][1]
    D1_drug[i+1] = y[-1][2]
    D2_drug[i+1] = y[-1][3]

    ''' update '''
    m.log_P.MEAS = np.log10(P_cell[i+1])  # insert measurement
    m.log_P.SP = np.log10(P_sp[i+1]) # P_sp is predefined trajectory points
    
 
    ''' solve MPC '''
    m.solve(disp=True)

错误码‘位置5’的一个在线案例是由于该方程中缺少了"dt()“。看起来很相似但不是我的案子。有人能帮我吗？提前谢谢！！

Answer 1

此错误通过不使用保留关键字来命名变量来解决。

name = 'log_P'

像lg_P这样的变量名可以工作。以下是APMonitor中的保留关键字的列表

abs()   Absolute value  abs(x*y)=0
exp()   Exponentiation  exp(x*y)=0
log10() Base-10 Log log10(x*y)=0
log()   Natural Log log(x*y)=0
sqrt()  Square Root sqrt(x*y)=0
sinh()  Hyperbolic Sine sinh(x*y)=0
cosh()  Hyperbolic Cosine   cosh(x*y)=0
tanh()  Hyperbolic Tangent  tanh(x*y)=0
sin()   Sine    sin(x*y)=0
cos()   Cosine  cos(x*y)=0
tan()   Tangent tan(x*y)=0
asin()  Arc-sine    asin(x*y)=0
acos()  Arc-cos acos(x*y)=0
atan()  Arc-tangent atan(x*y)=0
erf()   Error function  erf(x*y)=0
erfc()  Complementary error function    erfc(x*y)=0