Permalink
52 lines (45 sloc) 2.06 KB
import numpy as np
from gym.envs.mujoco import mujoco_env
from gym import utils
def mass_center(model, sim):
mass = np.expand_dims(model.body_mass, 1)
xpos = sim.data.xipos
return (np.sum(mass * xpos, 0) / np.sum(mass))[0]
class HumanoidEnv(mujoco_env.MujocoEnv, utils.EzPickle):
def __init__(self):
mujoco_env.MujocoEnv.__init__(self, 'humanoid.xml', 5)
utils.EzPickle.__init__(self)
def _get_obs(self):
data = self.sim.data
return np.concatenate([data.qpos.flat[2:],
data.qvel.flat,
data.cinert.flat,
data.cvel.flat,
data.qfrc_actuator.flat,
data.cfrc_ext.flat])
def step(self, a):
pos_before = mass_center(self.model, self.sim)
self.do_simulation(a, self.frame_skip)
pos_after = mass_center(self.model, self.sim)
alive_bonus = 5.0
data = self.sim.data
lin_vel_cost = 0.25 * (pos_after - pos_before) / self.model.opt.timestep
quad_ctrl_cost = 0.1 * np.square(data.ctrl).sum()
quad_impact_cost = .5e-6 * np.square(data.cfrc_ext).sum()
quad_impact_cost = min(quad_impact_cost, 10)
reward = lin_vel_cost - quad_ctrl_cost - quad_impact_cost + alive_bonus
qpos = self.sim.data.qpos
done = bool((qpos[2] < 1.0) or (qpos[2] > 2.0))
return self._get_obs(), reward, done, dict(reward_linvel=lin_vel_cost, reward_quadctrl=-quad_ctrl_cost, reward_alive=alive_bonus, reward_impact=-quad_impact_cost)
def reset_model(self):
c = 0.01
self.set_state(
self.init_qpos + self.np_random.uniform(low=-c, high=c, size=self.model.nq),
self.init_qvel + self.np_random.uniform(low=-c, high=c, size=self.model.nv,)
)
return self._get_obs()
def viewer_setup(self):
self.viewer.cam.trackbodyid = 1
self.viewer.cam.distance = self.model.stat.extent * 1.0
self.viewer.cam.lookat[2] = 2.0
self.viewer.cam.elevation = -20