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cartpole_swingup.py
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cartpole_swingup.py
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"""
Cart pole swing-up: Identical version to PILCO V0.9
"""
import logging
import math
import gym
from gym import spaces
from gym.utils import seeding
import numpy as np
logger = logging.getLogger(__name__)
class CartPoleSwingUpEnv(gym.Env):
metadata = {
'render.modes': ['human', 'rgb_array'],
'video.frames_per_second' : 50
}
def __init__(self):
self.g = 9.82 # gravity
self.m_c = 0.5 # cart mass
self.m_p = 0.5 # pendulum mass
self.total_m = (self.m_p + self.m_c)
self.l = 0.6 # pole's length
self.m_p_l = (self.m_p*self.l)
self.force_mag = 10.0
self.dt = 0.1 # seconds between state updates
self.b = 0.1 # friction coefficient
# Angle at which to fail the episode
self.theta_threshold_radians = 12 * 2 * math.pi / 360
self.x_threshold = 2.4
high = np.array([
np.finfo(np.float32).max,
np.finfo(np.float32).max,
np.finfo(np.float32).max,
np.finfo(np.float32).max])
self.action_space = spaces.Box(-self.force_mag, self.force_mag, shape=(1,))
self.observation_space = spaces.Box(-high, high)
self._seed()
self.viewer = None
self.state = None
def _seed(self, seed=None):
self.np_random, seed = seeding.np_random(seed)
return [seed]
def _step(self, action):
# Valid action
action = np.clip(action, -self.force_mag, self.force_mag)[0]
state = self.state
x, x_dot, theta, theta_dot = state
s = math.sin(theta)
c = math.cos(theta)
xdot_update = (-2*self.m_p_l*(theta_dot**2)*s + 3*self.m_p*self.g*s*c + 4*action - 4*self.b*x_dot)/(4*self.total_m - 3*self.m_p*c**2)
thetadot_update = (-3*self.m_p_l*(theta_dot**2)*s*c + 6*self.total_m*self.g*s + 6*(action - self.b*x_dot)*c)/(4*self.l*self.total_m - 3*self.m_p_l*c**2)
x = x + x_dot*self.dt
theta = theta + theta_dot*self.dt
x_dot = x_dot + xdot_update*self.dt
theta_dot = theta_dot + thetadot_update*self.dt
self.state = (x,x_dot,theta,theta_dot)
# compute costs - saturation cost
goal = np.array([0.0, self.l])
pole_x = self.l*np.sin(theta)
pole_y = self.l*np.cos(theta)
position = np.array([self.state[0] + pole_x, pole_y])
squared_distance = np.sum((position - goal)**2)
squared_sigma = 0.25**2
costs = 1 - np.exp(-0.5*squared_distance/squared_sigma)
return np.array(self.state), -costs, False, {}
def _reset(self):
#self.state = self.np_random.normal(loc=np.array([0.0, 0.0, 30*(2*np.pi)/360, 0.0]), scale=np.array([0.0, 0.0, 0.0, 0.0]))
self.state = self.np_random.normal(loc=np.array([0.0, 0.0, np.pi, 0.0]), scale=np.array([0.02, 0.02, 0.02, 0.02]))
self.steps_beyond_done = None
return np.array(self.state)
def _render(self, mode='human', close=False):
if close:
if self.viewer is not None:
self.viewer.close()
self.viewer = None
return
screen_width = 600
screen_height = 400
world_width = 5 # max visible position of cart
scale = screen_width/world_width
carty = 200 # TOP OF CART
polewidth = 6.0
polelen = scale*self.l # 0.6 or self.l
cartwidth = 40.0
cartheight = 20.0
if self.viewer is None:
from gym.envs.classic_control import rendering
self.viewer = rendering.Viewer(screen_width, screen_height)
l,r,t,b = -cartwidth/2, cartwidth/2, cartheight/2, -cartheight/2
cart = rendering.FilledPolygon([(l,b), (l,t), (r,t), (r,b)])
self.carttrans = rendering.Transform()
cart.add_attr(self.carttrans)
cart.set_color(1, 0, 0)
self.viewer.add_geom(cart)
l,r,t,b = -polewidth/2,polewidth/2,polelen-polewidth/2,-polewidth/2
pole = rendering.FilledPolygon([(l,b), (l,t), (r,t), (r,b)])
pole.set_color(0, 0, 1)
self.poletrans = rendering.Transform(translation=(0, 0))
pole.add_attr(self.poletrans)
pole.add_attr(self.carttrans)
self.viewer.add_geom(pole)
self.axle = rendering.make_circle(polewidth/2)
self.axle.add_attr(self.poletrans)
self.axle.add_attr(self.carttrans)
self.axle.set_color(0.1, 1, 1)
self.viewer.add_geom(self.axle)
# Make another circle on the top of the pole
self.pole_bob = rendering.make_circle(polewidth/2)
self.pole_bob_trans = rendering.Transform()
self.pole_bob.add_attr(self.pole_bob_trans)
self.pole_bob.add_attr(self.poletrans)
self.pole_bob.add_attr(self.carttrans)
self.pole_bob.set_color(0, 0, 0)
self.viewer.add_geom(self.pole_bob)
self.wheel_l = rendering.make_circle(cartheight/4)
self.wheel_r = rendering.make_circle(cartheight/4)
self.wheeltrans_l = rendering.Transform(translation=(-cartwidth/2, -cartheight/2))
self.wheeltrans_r = rendering.Transform(translation=(cartwidth/2, -cartheight/2))
self.wheel_l.add_attr(self.wheeltrans_l)
self.wheel_l.add_attr(self.carttrans)
self.wheel_r.add_attr(self.wheeltrans_r)
self.wheel_r.add_attr(self.carttrans)
self.wheel_l.set_color(0, 0, 0) # Black, (B, G, R)
self.wheel_r.set_color(0, 0, 0) # Black, (B, G, R)
self.viewer.add_geom(self.wheel_l)
self.viewer.add_geom(self.wheel_r)
self.track = rendering.Line((0,carty - cartheight/2 - cartheight/4), (screen_width,carty - cartheight/2 - cartheight/4))
self.track.set_color(0,0,0)
self.viewer.add_geom(self.track)
if self.state is None: return None
x = self.state
cartx = x[0]*scale+screen_width/2.0 # MIDDLE OF CART
self.carttrans.set_translation(cartx, carty)
self.poletrans.set_rotation(x[2])
self.pole_bob_trans.set_translation(-self.l*np.sin(x[2]), self.l*np.cos(x[2]))
return self.viewer.render(return_rgb_array = mode=='rgb_array')