in mbrl/env/cartpole_continuous.py [0:0]
def step(self, action):
action = action.squeeze()
x, x_dot, theta, theta_dot = self.state
force = action * self.force_mag
costheta = math.cos(theta)
sintheta = math.sin(theta)
# For the interested reader:
# https://coneural.org/florian/papers/05_cart_pole.pdf
temp = (
force + self.polemass_length * theta_dot ** 2 * sintheta
) / self.total_mass
thetaacc = (self.gravity * sintheta - costheta * temp) / (
self.length * (4.0 / 3.0 - self.masspole * costheta ** 2 / self.total_mass)
)
xacc = temp - self.polemass_length * thetaacc * costheta / self.total_mass
if self.kinematics_integrator == "euler":
x = x + self.tau * x_dot
x_dot = x_dot + self.tau * xacc
theta = theta + self.tau * theta_dot
theta_dot = theta_dot + self.tau * thetaacc
else: # semi-implicit euler
x_dot = x_dot + self.tau * xacc
x = x + self.tau * x_dot
theta_dot = theta_dot + self.tau * thetaacc
theta = theta + self.tau * theta_dot
self.state = (x, x_dot, theta, theta_dot)
done = bool(
x < -self.x_threshold
or x > self.x_threshold
or theta < -self.theta_threshold_radians
or theta > self.theta_threshold_radians
)
if not done:
reward = 1.0
elif self.steps_beyond_done is None:
# Pole just fell!
self.steps_beyond_done = 0
reward = 1.0
else:
if self.steps_beyond_done == 0:
logger.warn(
"You are calling 'step()' even though this "
"environment has already returned done = True. You "
"should always call 'reset()' once you receive 'done = "
"True' -- any further steps are undefined behavior."
)
self.steps_beyond_done += 1
reward = 0.0
return np.array(self.state), reward, done, {}