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task.py
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task.py
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import numpy as np
from physics_sim import PhysicsSim
class Task():
"""Task (environment) that defines the goal and provides feedback to the agent."""
def __init__(self, init_pose=None, init_velocities=None,
init_angle_velocities=None, runtime=5., target_pos=None):
"""Initialize a Task object.
Params
======
init_pose: initial position of the quadcopter in (x,y,z) dimensions and the Euler angles
init_velocities: initial velocity of the quadcopter in (x,y,z) dimensions
init_angle_velocities: initial radians/second for each of the three Euler angles
runtime: time limit for each episode
target_pos: target/goal (x,y,z) position for the agent
"""
# Simulation
self.sim = PhysicsSim(init_pose, init_velocities, init_angle_velocities, runtime)
self.action_repeat = 3
self.state_size = self.action_repeat * 6
self.action_low = 0
self.action_high = 900
self.action_size = 4
# Goal
self.target_pos = target_pos if target_pos is not None else np.array([0., 0., 10.])
def get_reward(self):
"""Uses current pose of sim to return reward."""
reward = 1.-.05*(np.linalg.norm(self.sim.pose[:3] - self.target_pos))
# reward = 1. if reward > 0 else -1.
return reward
def step(self, rotor_speeds):
"""Uses action to obtain next state, reward, done."""
reward = 0
pose_all = []
for _ in range(self.action_repeat):
done = self.sim.next_timestep(rotor_speeds) # update the sim pose and velocities
reward += self.get_reward()
pose_all.append(self.sim.pose)
next_state = np.concatenate(pose_all)
return next_state, reward, done
def reset(self):
"""Reset the sim to start a new episode."""
self.sim.reset()
state = np.concatenate([self.sim.pose] * self.action_repeat)
return state