CODEWITHSUNDEEP
sympynonlinear-optimizationequation-solvingnonlinear-equation
sherry12555
sherry12555

Reputation: 1

Hello I am new to sympy and I am trying to solve a couple of non-linear equation

here is the problem:

constants: enter image description here

dependent value functions:

def v_ego(self,ego_vel_x,ego_a_ini_x,t):
    v_ego = ego_vel_x + ego_a_ini_x * t
    return v_ego

def x_obj(self,x_obj_ini,obj_vel_x,obj_a_ini_x,t):
    x_obj = x_obj_ini + obj_vel_x * t + 0.5 * obj_a_ini_x * t ** 2

    return x_obj

def x_ego(self,x_ego_ini,ego_vel_x,ego_a_ini_x,t):
    x_ego = x_ego_ini + ego_vel_x * t + 0.5 * ego_a_ini_x * t ** 2
    return x_ego

def y_obj(self,y_obj_ini,obj_vel_y,obj_a_ini_y,t):
    y_obj = y_obj_ini + obj_vel_y * t + 0.5 * obj_a_ini_y * t ** 2
    return y_obj

def y_t(self):
    y_t = math.sqrt(self._r_t ** 2 - self._l_f ** 2) - (self._w_ego / 2)

    return y_t

def y_r(self,ego_vel_x,ego_a_ini_x,t):
    y_r = math.sqrt(max(0, ((self.v_ego(ego_vel_x,ego_a_ini_x,t) ** 2 / (self
                                                                         ._Mu_rt * self._g)) ** 2 - self._l_c ** 2)))
    return y_r

def y_min(self,ego_vel_x,ego_a_ini_x,t):
    y_min = max(self.y_t(), self.y_r(ego_vel_x,ego_a_ini_x,t))
    return y_min

def r_min(self,ego_vel_x,ego_a_ini_x,t):
    r_min = max(self._r_t, math.sqrt(self._l_f ** 2 + (self.y_min(ego_vel_x,ego_a_ini_x,t) + self._w_ego / 2) ** 2))
    return r_min

tts, delta_t = sym.symbols('tts,delta_t')

e_10 = sym.Eq(math.atan((self.x_obj(x_obj_ini, obj_vel_x, obj_a_ini_x, tts + delta_t) - self.x_ego(x_ego_ini,ego_vel_x,ego_a_ini_x,tts)+ self._l_f) / (self.y_min(ego_vel_x, ego_a_ini_x, tts) - self.y_obj(y_obj_ini, obj_vel_y, obj_a_ini_y,tts + delta_t))) - ((self.v_ego(ego_vel_x, ego_a_ini_x, tts) * delta_t) / self.r_min(ego_vel_x, ego_a_ini_x, tts) - (math.asin(min(1.0, self._l_f / self.r_min(ego_vel_x, ego_a_ini_x, tts))))), 0)

e_11 = sym.Eq((self.x_obj(x_obj_ini, obj_vel_x, obj_a_ini_x, tts + delta_t) - self.x_ego(x_ego_ini, ego_vel_x,ego_a_ini_x,tts)+ self._l_f) ** 2 + (self.y_min(ego_vel_x, ego_a_ini_x, tts) - self.y_obj(y_obj_ini, obj_vel_y, obj_a_ini_y,tts + delta_t)) ** 2 - (self.r_min(ego_vel_x, ego_a_ini_x, tts)) ** 2, 0)
print(sym.solve([e_10, e_11], (tts, delta_t)))

I am getting TypeError: cannot determine truth value of Relational

These are the equations: non linear equations that I am trying to solve

and these are the dependent values that need to be calculated:

dependent functions

any help is appreciated

Upvotes: 0

Views: 47

Answers (1)

smichr
smichr

Reputation: 19135

When you use min with a SymPy expressions, it will complain if it can't figure out what the min is, e.g. min(x,y) -> TypeError: cannot determine truth value of Relational.

Since you are only selecting a minimum of two values, the function is easy to write as a Piecewise as in the following example where the equation x - min(y,z) is being solved.

enter image description here

Replace max with a similar rewrite, too.

Upvotes: 0

Related Questions