bullet3/examples/pybullet/gym/pybullet_envs/gym_locomotion_envs.py

from .scene_stadium import SinglePlayerStadiumScene
from .env_bases import MJCFBaseBulletEnv
import numpy as np
import pybullet as p
from robot_locomotors import Hopper, Walker2D, HalfCheetah, Ant, Humanoid, HumanoidFlagrun, HumanoidFlagrunHarder


class WalkerBaseBulletEnv(MJCFBaseBulletEnv):
	def __init__(self, robot, render=False):
		print("WalkerBase::__init__ start")
		MJCFBaseBulletEnv.__init__(self, robot, render)
		
		self.camera_x = 0
		self.walk_target_x = 1e3  # kilometer away
		self.walk_target_y = 0
		self.stateId=-1
		

	def create_single_player_scene(self):
		self.stadium_scene = SinglePlayerStadiumScene(gravity=9.8, timestep=0.0165/4, frame_skip=4)
		return self.stadium_scene

	def _reset(self):
		if (self.stateId>=0):
			#print("restoreState self.stateId:",self.stateId)
			p.restoreState(self.stateId)
		
		r = MJCFBaseBulletEnv._reset(self)
		p.configureDebugVisualizer(p.COV_ENABLE_RENDERING,0)

		self.parts, self.jdict, self.ordered_joints, self.robot_body = self.robot.addToScene(
			self.stadium_scene.ground_plane_mjcf)
		self.ground_ids = set([(self.parts[f].bodies[self.parts[f].bodyIndex], self.parts[f].bodyPartIndex) for f in
							   self.foot_ground_object_names])
		p.configureDebugVisualizer(p.COV_ENABLE_RENDERING,1)
		if (self.stateId<0):
			self.stateId=p.saveState()
			#print("saving state self.stateId:",self.stateId)
			
		
		return r

	def move_robot(self, init_x, init_y, init_z):
		"Used by multiplayer stadium to move sideways, to another running lane."
		self.cpp_robot.query_position()
		pose = self.cpp_robot.root_part.pose()
		pose.move_xyz(init_x, init_y, init_z)  # Works because robot loads around (0,0,0), and some robots have z != 0 that is left intact
		self.cpp_robot.set_pose(pose)

	electricity_cost	 = -2.0	# cost for using motors -- this parameter should be carefully tuned against reward for making progress, other values less improtant
	stall_torque_cost	= -0.1	# cost for running electric current through a motor even at zero rotational speed, small
	foot_collision_cost  = -1.0	# touches another leg, or other objects, that cost makes robot avoid smashing feet into itself
	foot_ground_object_names = set(["floor"])  # to distinguish ground and other objects
	joints_at_limit_cost = -0.1	# discourage stuck joints

	def _step(self, a):
		if not self.scene.multiplayer:  # if multiplayer, action first applied to all robots, then global step() called, then _step() for all robots with the same actions
			self.robot.apply_action(a)
			self.scene.global_step()

		state = self.robot.calc_state()  # also calculates self.joints_at_limit

		alive = float(self.robot.alive_bonus(state[0]+self.robot.initial_z, self.robot.body_rpy[1]))   # state[0] is body height above ground, body_rpy[1] is pitch
		done = alive < 0
		if not np.isfinite(state).all():
			print("~INF~", state)
			done = True

		potential_old = self.potential
		self.potential = self.robot.calc_potential()
		progress = float(self.potential - potential_old)

		feet_collision_cost = 0.0
		for i,f in enumerate(self.robot.feet): # TODO: Maybe calculating feet contacts could be done within the robot code
			contact_ids = set((x[2], x[4]) for x in f.contact_list())
			#print("CONTACT OF '%d' WITH %d" % (contact_ids, ",".join(contact_names)) )
			if (self.ground_ids & contact_ids):
                        	#see Issue 63: https://github.com/openai/roboschool/issues/63
				#feet_collision_cost += self.foot_collision_cost
				self.robot.feet_contact[i] = 1.0
			else:
				self.robot.feet_contact[i] = 0.0


		electricity_cost  = self.electricity_cost  * float(np.abs(a*self.robot.joint_speeds).mean())  # let's assume we have DC motor with controller, and reverse current braking
		electricity_cost += self.stall_torque_cost * float(np.square(a).mean())

		joints_at_limit_cost = float(self.joints_at_limit_cost * self.robot.joints_at_limit)
		debugmode=0
		if(debugmode):
			print("alive=")
			print(alive)
			print("progress")
			print(progress)
			print("electricity_cost")
			print(electricity_cost)
			print("joints_at_limit_cost")
			print(joints_at_limit_cost)
			print("feet_collision_cost")
			print(feet_collision_cost)

		self.rewards = [
			alive,
			progress,
			electricity_cost,
			joints_at_limit_cost,
			feet_collision_cost
			]
		if (debugmode):
			print("rewards=")
			print(self.rewards)
			print("sum rewards")
			print(sum(self.rewards))
		self.HUD(state, a, done)
		self.reward += sum(self.rewards)

		return state, sum(self.rewards), bool(done), {}

	def camera_adjust(self):
		x, y, z = self.body_xyz
		self.camera_x = 0.98*self.camera_x + (1-0.98)*x
		self.camera.move_and_look_at(self.camera_x, y-2.0, 1.4, x, y, 1.0)

class HopperBulletEnv(WalkerBaseBulletEnv):
	def __init__(self):
		self.robot = Hopper()
		WalkerBaseBulletEnv.__init__(self, self.robot)

class Walker2DBulletEnv(WalkerBaseBulletEnv):
	def __init__(self):
		self.robot = Walker2D()
		WalkerBaseBulletEnv.__init__(self, self.robot)

class HalfCheetahBulletEnv(WalkerBaseBulletEnv):
	def __init__(self):
		self.robot = HalfCheetah()
		WalkerBaseBulletEnv.__init__(self, self.robot)

class AntBulletEnv(WalkerBaseBulletEnv):
	def __init__(self):
		self.robot = Ant()
		WalkerBaseBulletEnv.__init__(self, self.robot)

class HumanoidBulletEnv(WalkerBaseBulletEnv):
	def __init__(self, robot=Humanoid()):
		self.robot = robot
		WalkerBaseBulletEnv.__init__(self, self.robot)
		self.electricity_cost  = 4.25*WalkerBaseBulletEnv.electricity_cost
		self.stall_torque_cost = 4.25*WalkerBaseBulletEnv.stall_torque_cost

class HumanoidFlagrunBulletEnv(HumanoidBulletEnv):
	random_yaw = True

	def __init__(self):
		self.robot = HumanoidFlagrun()
		HumanoidBulletEnv.__init__(self, self.robot)

	def create_single_player_scene(self):
		s = HumanoidBulletEnv.create_single_player_scene(self)
		s.zero_at_running_strip_start_line = False
		return s

class HumanoidFlagrunHarderBulletEnv(HumanoidBulletEnv):
	random_lean = True  # can fall on start

	def __init__(self):
		self.robot = HumanoidFlagrunHarder()
		self.electricity_cost /= 4   # don't care that much about electricity, just stand up!
		HumanoidBulletEnv.__init__(self, self.robot)

	def create_single_player_scene(self):
		s = HumanoidBulletEnv.create_single_player_scene(self)
		s.zero_at_running_strip_start_line = False
		return s