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go2_rl_gym/legged_gym/envs/base/legged_robot.py

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78 KiB
Python

from itertools import product
from legged_gym import LEGGED_GYM_ROOT_DIR, envs
import time
from warnings import WarningMessage
import numpy as np
import os
from isaacgym.torch_utils import *
from isaacgym import gymtorch, gymapi, gymutil
import torch
from torch import Tensor
from typing import Tuple, Dict
from legged_gym import LEGGED_GYM_ROOT_DIR
from legged_gym.envs.base.base_task import BaseTask
from legged_gym.utils.math import wrap_to_pi, quat_apply_yaw
from legged_gym.utils.isaacgym_utils import get_euler_xyz as get_euler_xyz_in_tensor
from legged_gym.utils.isaacgym_utils import sample_disjoint_intervals, sample_single_interval
from legged_gym.utils.helpers import class_to_dict
from .legged_robot_config import LeggedRobotCfg
from legged_gym.utils.terrain import Terrain
class LeggedRobot(BaseTask):
def __init__(self, cfg: LeggedRobotCfg, sim_params, physics_engine, sim_device, headless):
""" Parses the provided config file,
calls create_sim() (which creates, simulation and environments),
initilizes pytorch buffers used during training
Args:
cfg (Dict): Environment config file
sim_params (gymapi.SimParams): simulation parameters
physics_engine (gymapi.SimType): gymapi.SIM_PHYSX (must be PhysX)
device_type (string): 'cuda' or 'cpu'
device_id (int): 0, 1, ...
headless (bool): Run without rendering if True
"""
self.cfg = cfg
self.sim_params = sim_params
self.height_samples = None
self.debug_viz = False
self.init_done = False
self._parse_cfg(self.cfg)
super().__init__(self.cfg, sim_params, physics_engine, sim_device, headless)
if not self.headless:
self.set_camera(self.cfg.viewer.pos, self.cfg.viewer.lookat)
self._init_buffers()
self._prepare_reward_function()
self.init_done = True
self.reward_curriculum_scales = {}
self.reward_curriculum_configs = []
if hasattr(self.cfg.rewards, "curriculum_rewards") and self.cfg.rewards.curriculum_rewards is not None:
self.reward_curriculum_configs = self.cfg.rewards.curriculum_rewards
for config in self.reward_curriculum_configs:
self.reward_curriculum_scales[config['reward_name']] = config['start_value']
self.num_steps_per_env = 24 # PPO default num_steps_per_env
def step(self, actions):
""" Apply actions, simulate, call self.post_physics_step()
Args:
actions (torch.Tensor): Tensor of shape (num_envs, num_actions_per_env)
"""
clip_actions = self.cfg.normalization.clip_actions
self.actions = torch.clip(actions, -clip_actions, clip_actions).to(self.device)
# step physics and render each frame
self.render()
if self.cfg.domain_rand.randomize_action_delay:
actions_start_decimation = torch.randint(0, self.cfg.control.decimation+1, (self.num_envs, 1), device=self.device)
for i in range(self.cfg.control.decimation):
if self.cfg.domain_rand.randomize_action_delay:
use_actions = (i >= actions_start_decimation).float()
input_actions = (1 - use_actions) * self.last_actions + use_actions * self.actions
else:
input_actions = self.actions
self.torques = self._compute_torques(input_actions).view(self.torques.shape)
if self.cfg.domain_rand.randomize_motor_strength:
self.torques *= self.motor_strengths
self.gym.set_dof_actuation_force_tensor(self.sim, gymtorch.unwrap_tensor(self.torques))
self.gym.simulate(self.sim)
if self.cfg.env.test:
elapsed_time = self.gym.get_elapsed_time(self.sim)
sim_time = self.gym.get_sim_time(self.sim)
if sim_time-elapsed_time>0:
time.sleep(sim_time-elapsed_time)
if self.device == 'cpu':
self.gym.fetch_results(self.sim, True)
self.gym.refresh_dof_state_tensor(self.sim)
self.post_physics_step()
# return clipped obs, clipped states (None), rewards, dones and infos
clip_obs = self.cfg.normalization.clip_observations
self.obs_buf = torch.clip(self.obs_buf, -clip_obs, clip_obs)
if self.privileged_obs_buf is not None:
self.privileged_obs_buf = torch.clip(self.privileged_obs_buf, -clip_obs, clip_obs)
return self.obs_buf, self.privileged_obs_buf, self.rew_buf, self.reset_buf, self.extras
def post_physics_step(self):
""" check terminations, compute observations and rewards
calls self._post_physics_step_callback() for common computations
calls self._draw_debug_vis() if needed
"""
self.gym.refresh_actor_root_state_tensor(self.sim)
self.gym.refresh_net_contact_force_tensor(self.sim)
self.gym.refresh_rigid_body_state_tensor(self.sim)
self.episode_length_buf += 1
self.common_step_counter += 1
self.commands_resampling_step -= 1
if self.cfg.init_state.turn_over:
self.turn_over_timer = (self.turn_over_timer - self.dt).clip(min=0.0)
self.update_reward_curriculum()
# prepare quantities
self.base_pos[:] = self.root_states[:, 0:3]
self.base_quat[:] = self.root_states[:, 3:7]
self.rpy[:] = get_euler_xyz_in_tensor(self.base_quat[:])
self.base_lin_vel[:] = quat_rotate_inverse(self.base_quat, self.root_states[:, 7:10])
self.base_ang_vel[:] = quat_rotate_inverse(self.base_quat, self.root_states[:, 10:13])
self.projected_gravity[:] = quat_rotate_inverse(self.base_quat, self.gravity_vec)
self.max_move_distance = self.max_move_distance.maximum(torch.norm(self.root_states[:, :2] - self.env_origins[:, :2], dim=1))
self._post_physics_step_callback()
# compute observations, rewards, resets, ...
self.check_termination()
self.compute_reward()
env_ids = self.reset_buf.nonzero(as_tuple=False).flatten()
self.reset_idx(env_ids)
if self.cfg.domain_rand.push_robots:
self._push_robots()
self.compute_observations() # in some cases a simulation step might be required to refresh some obs (for example body positions)
self.last_actions[:] = self.actions[:]
self.last_dof_vel[:] = self.dof_vel[:]
self.last_root_vel[:] = self.root_states[:, 7:13]
def update_reward_curriculum(self, force_update: bool = False):
# update reward curriculum
if self.reward_curriculum_configs:
if self.common_step_counter % self.num_steps_per_env == 0 or force_update:
for config in self.reward_curriculum_configs:
current_scale = self.get_current_scale(config)
reward_name = config['reward_name']
self.reward_curriculum_scales[reward_name] = current_scale
def get_current_scale(self, config):
""" config: Dict
{'start_iter': 0, 'end_iter': 1500, 'start_value': 1.0, 'end_value': 0.0}
"""
current_iter = self.common_step_counter // self.num_steps_per_env
cfg_start_iter = config['start_iter']
cfg_end_iter = config['end_iter']
cfg_start_val = config['start_value']
cfg_end_val = config['end_value']
percentage = (current_iter - cfg_start_iter) / (cfg_end_iter - cfg_start_iter)
percentage = max(min(percentage, 1.0), 0.0)
current_scale = (1.0 - percentage) * cfg_start_val + percentage * cfg_end_val
return current_scale
def check_termination(self):
""" Check if environments need to be reset
"""
self.reset_buf = torch.zeros(self.num_envs, dtype=torch.bool, device=self.device)
if not self.cfg.init_state.turn_over:
self.reset_buf = torch.any(torch.norm(self.contact_forces[:, self.termination_contact_indices, :], dim=-1) > 1., dim=1)
# self.reset_buf |= torch.logical_or(torch.abs(self.rpy[:,1])>1.0, torch.abs(self.rpy[:,0])>0.8)
self.time_out_buf = self.episode_length_buf > self.max_episode_length # no terminal reward for time-outs
self.reset_buf |= self.time_out_buf
def reset_idx(self, env_ids):
""" Reset some environments.
Calls self._reset_dofs(env_ids), self._reset_root_states(env_ids), and self._resample_commands(env_ids)
[Optional] calls self._update_terrain_curriculum(env_ids), self.update_command_curriculum(env_ids) and
Logs episode info
Resets some buffers
Args:
env_ids (list[int]): List of environment ids which must be reset
"""
if len(env_ids) == 0:
return
### Domain randomizations ###
# randomization of the motor strength
if self.cfg.domain_rand.randomize_motor_strength:
rng = self.cfg.domain_rand.motor_strength_range
self.motor_strengths[env_ids] = torch_rand_float(
rng[0], rng[1], (len(env_ids), self.num_actions), device=self.device
)
# randomization of the motor zero calibration for real machine
if self.cfg.domain_rand.randomize_motor_zero_offset:
self.motor_zero_offsets[env_ids] = torch_rand_float(self.cfg.domain_rand.motor_zero_offset_range[0], self.cfg.domain_rand.motor_zero_offset_range[1], (len(env_ids), self.num_actions), device=self.device)
# randomization of the motor pd gains
if self.cfg.domain_rand.randomize_pd_gains:
self.p_gains_multiplier[env_ids] = torch_rand_float(self.cfg.domain_rand.stiffness_multiplier_range[0], self.cfg.domain_rand.stiffness_multiplier_range[1], (len(env_ids), self.num_actions), device=self.device)
self.d_gains_multiplier[env_ids] = torch_rand_float(self.cfg.domain_rand.damping_multiplier_range[0], self.cfg.domain_rand.damping_multiplier_range[1], (len(env_ids), self.num_actions), device=self.device)
# update terrain curriculum before reset root states
if self.cfg.terrain.curriculum:
self._update_terrain_curriculum(env_ids)
# reset robot states
self._reset_dofs(env_ids)
self._reset_root_states(env_ids)
# reset buffers
self.actions[env_ids] = 0.
self.last_actions[env_ids] = 0.
self.last_dof_vel[env_ids] = 0.
self.feet_air_time[env_ids] = 0.
self.episode_length_buf[env_ids] = 0
self.reset_buf[env_ids] = 1
self.commands_resampling_step[env_ids] = self.cfg.commands.resampling_time / self.dt
self.commands_xy_accumulation[env_ids] = 0.0
if self.cfg.commands.curriculum:
self.update_command_curriculum(env_ids)
self._resample_commands(env_ids)
# fill extras
self.extras["episode"] = {}
if self.cfg.terrain.mesh_type in ["heightfield", "trimesh"]:
self.extras["episode"]['terrain_level_all'] = torch.mean(self.terrain_levels.float())
for name, cols in self.terrain.name2cols.items():
if isinstance(cols, set):
cols = self.terrain.name2cols[name] = torch.tensor(list(cols), device=self.device)
self.extras["episode"]['terrain_level_' + name] = torch.mean(self.terrain_levels[torch.isin(self.terrain_types, cols)].float())
else:
self.extras["episode"]['terrain_level_all'] = 0.0
for key in self.episode_sums.keys():
self.extras["episode"]['rew_' + key] = torch.mean(self.episode_sums[key][env_ids]) / self.max_episode_length_s
self.episode_sums[key][env_ids] = 0.
if self.cfg.commands.curriculum:
self.extras["episode"]["max_command_x"] = self.command_ranges["lin_vel_x"][1]
# send timeout info to the algorithm
if self.cfg.env.send_timeouts:
self.extras["time_outs"] = self.time_out_buf
def compute_reward(self):
""" Compute rewards
Calls each reward function which had a non-zero scale (processed in self._prepare_reward_function())
adds each terms to the episode sums and to the total reward
"""
self.rew_buf[:] = 0.
for i in range(len(self.reward_functions)):
name = self.reward_names[i]
raw_rew = self.reward_functions[i]()
rew = raw_rew * self.reward_scales.get(name, 0.0)
if self.cfg.init_state.turn_over:
turn_over_rew = raw_rew * self.reward_turn_over_scales.get(name, 0.0)
if name in self.reward_curriculum_scales:
rew *= self.reward_curriculum_scales[name]
if self.cfg.init_state.turn_over:
turn_over_rew *= self.reward_curriculum_scales[name]
if self.cfg.init_state.turn_over:
need_turn_over = self.rpy[:, 0].abs() > self.cfg.rewards.turn_over_roll_threshold
rew = torch.where(need_turn_over, turn_over_rew, rew)
self.rew_buf += rew
self.episode_sums[name] += rew
if self.cfg.rewards.only_positive_rewards:
self.rew_buf[:] = torch.clip(self.rew_buf[:], min=0.)
# add termination reward after clipping
if "termination" in self.reward_scales:
rew = self._reward_termination() * self.reward_scales["termination"]
self.rew_buf += rew
self.episode_sums["termination"] += rew
def compute_observations(self):
""" Computes observations
"""
self.obs_buf = torch.cat(( self.base_lin_vel * self.obs_scales.lin_vel,
self.base_ang_vel * self.obs_scales.ang_vel,
self.projected_gravity,
self.commands[:, :3] * self.commands_scale,
(self.dof_pos - self.default_dof_pos) * self.obs_scales.dof_pos,
self.dof_vel * self.obs_scales.dof_vel,
self.actions
),dim=-1)
# add perceptive inputs if not blind
# add noise if needed
if self.add_noise:
self.obs_buf += (2 * torch.rand_like(self.obs_buf) - 1) * self.noise_scale_vec
def create_sim(self):
""" Creates simulation, terrain and evironments
"""
self.up_axis_idx = 2 # 2 for z, 1 for y -> adapt gravity accordingly
self.sim = self.gym.create_sim(self.sim_device_id, self.graphics_device_id, self.physics_engine, self.sim_params)
mesh_type = self.cfg.terrain.mesh_type
if mesh_type in ['heightfield', 'trimesh']:
self.terrain = Terrain(self.cfg.terrain, self.num_envs)
if mesh_type=='plane':
self._create_ground_plane()
elif mesh_type=='heightfield':
self._create_heightfield()
elif mesh_type=='trimesh':
self._create_trimesh()
elif mesh_type is not None:
raise ValueError("Terrain mesh type not recognised. Allowed types are [None, plane, heightfield, trimesh]")
self._create_envs()
def set_camera(self, position, lookat):
""" Set camera position and direction
"""
cam_pos = gymapi.Vec3(position[0], position[1], position[2])
cam_target = gymapi.Vec3(lookat[0], lookat[1], lookat[2])
self.gym.viewer_camera_look_at(self.viewer, None, cam_pos, cam_target)
#------------- Callbacks --------------
def _process_rigid_shape_props(self, props, env_id):
""" Callback allowing to store/change/randomize the rigid shape properties of each environment.
Called During environment creation.
Base behavior: randomizes the friction of each environment
Args:
props (List[gymapi.RigidShapeProperties]): Properties of each shape of the asset
env_id (int): Environment id
Returns:
[List[gymapi.RigidShapeProperties]]: Modified rigid shape properties
"""
if self.cfg.domain_rand.randomize_friction:
if env_id==0:
# prepare friction randomization
friction_range = self.cfg.domain_rand.friction_range
num_buckets = 64
bucket_ids = torch.randint(0, num_buckets, (self.num_envs, 1))
friction_buckets = torch_rand_float(friction_range[0], friction_range[1], (num_buckets,1), device='cpu')
self.friction_coeffs = friction_buckets[bucket_ids]
for s in range(len(props)):
props[s].friction = self.friction_coeffs[env_id]
if self.cfg.domain_rand.randomize_restitution:
rand_restitution = np.random.uniform(self.cfg.domain_rand.restitution_range[0], self.cfg.domain_rand.restitution_range[1])
for s in range(len(props)):
props[s].restitution = rand_restitution
return props
def _process_dof_props(self, props, env_id):
""" Callback allowing to store/change/randomize the DOF properties of each environment.
Called During environment creation.
Base behavior: stores position, velocity and torques limits defined in the URDF
Args:
props (numpy.array): Properties of each DOF of the asset
env_id (int): Environment id
Returns:
[numpy.array]: Modified DOF properties
"""
if env_id==0:
self.dof_pos_limits = torch.zeros(self.num_dof, 2, dtype=torch.float, device=self.device, requires_grad=False)
self.dof_vel_limits = torch.zeros(self.num_dof, dtype=torch.float, device=self.device, requires_grad=False)
self.torque_limits = torch.zeros(self.num_dof, dtype=torch.float, device=self.device, requires_grad=False)
for i in range(len(props)):
self.dof_pos_limits[i, 0] = props["lower"][i].item()
self.dof_pos_limits[i, 1] = props["upper"][i].item()
self.dof_vel_limits[i] = props["velocity"][i].item()
self.torque_limits[i] = props["effort"][i].item()
# soft limits
m = (self.dof_pos_limits[i, 0] + self.dof_pos_limits[i, 1]) / 2
r = self.dof_pos_limits[i, 1] - self.dof_pos_limits[i, 0]
self.dof_pos_limits[i, 0] = m - 0.5 * r * self.cfg.rewards.soft_dof_pos_limit
self.dof_pos_limits[i, 1] = m + 0.5 * r * self.cfg.rewards.soft_dof_pos_limit
return props
def _process_rigid_body_props(self, props, env_id):
# if env_id==0:
# sum = 0
# for i, p in enumerate(props):
# sum += p.mass
# print(f"Mass of body {i}: {p.mass} (before randomization)")
# print(f"Total mass {sum} (before randomization)")
# randomize base mass
if self.cfg.domain_rand.randomize_base_mass:
rng = self.cfg.domain_rand.added_mass_range
props[0].mass += np.random.uniform(rng[0], rng[1])
# randomize link masses
if self.cfg.domain_rand.randomize_link_mass:
self.multiplied_link_masses_ratio = torch_rand_float(self.cfg.domain_rand.multiplied_link_mass_range[0], self.cfg.domain_rand.multiplied_link_mass_range[1], (1, self.num_bodies-1), device=self.device)
for i in range(1, len(props)):
props[i].mass *= self.multiplied_link_masses_ratio[0,i-1]
# randomize base com
if self.cfg.domain_rand.randomize_base_com:
self.added_base_com = torch_rand_float(self.cfg.domain_rand.added_base_com_range[0], self.cfg.domain_rand.added_base_com_range[1], (1, 3), device=self.device)
props[0].com += gymapi.Vec3(self.added_base_com[0, 0], self.added_base_com[0, 1],
self.added_base_com[0, 2])
return props
def _post_physics_step_callback(self):
""" Callback called before computing terminations, rewards, and observations
Default behaviour: Compute ang vel command based on target and heading, compute measured terrain heights and randomly push robots
"""
# env_ids = (self.episode_length_buf % int(self.cfg.commands.resampling_time / self.dt)==0).nonzero(as_tuple=False).flatten()
resampling_env_ids = ((self.commands_resampling_step <= 0.0) * (self.episode_length_buf < self.max_episode_length - 1)).nonzero(as_tuple=False).flatten()
self._resample_commands(resampling_env_ids)
if self.cfg.commands.heading_command:
mask = (self.stop_heading == 0.0)
forward = quat_apply(self.base_quat[mask], self.forward_vec[mask])
heading = torch.atan2(forward[:, 1], forward[:, 0])
self.commands[mask, 2] = torch.clip(
0.5*wrap_to_pi(self.commands[mask, 3] - heading),
self.env_command_ranges["ang_vel_yaw"][:, 0],
self.env_command_ranges["ang_vel_yaw"][:, 1]
)
if self.cfg.terrain.measure_heights:
self.measured_heights = self._get_heights()
def _resample_commands(self, env_ids):
""" Randommly select commands of some environments
Args:
env_ids (List[int]): Environments ids for which new commands are needed
"""
if len(env_ids) == 0:
return
self.stop_heading[env_ids] = False
# update command curriculum with train steps
if len(self.cfg.commands.command_range_curriculum):
current_iter = self.common_step_counter // self.num_steps_per_env
for i in range(len(self.cfg.commands.command_range_curriculum)-1, -1, -1): # iterate backwards to be able to pop entries
cfg = self.cfg.commands.command_range_curriculum[i]
if current_iter >= cfg["iter"]:
self.command_ranges["lin_vel_x"] = cfg["lin_vel_x"]
self.command_ranges["lin_vel_y"] = cfg["lin_vel_y"]
self.command_ranges["ang_vel_yaw"] = cfg["ang_vel_yaw"]
self.command_ranges["heading"] = cfg["heading"]
self.max_lin_vel = max(abs(self.command_ranges["lin_vel_x"][0]), abs(self.command_ranges["lin_vel_x"][1]),
abs(self.command_ranges["lin_vel_y"][0]), abs(self.command_ranges["lin_vel_y"][1]))
self.cfg.commands.command_range_curriculum.pop(i)
self._update_env_command_ranges()
print(f"Command range updated at iter {current_iter}: {self.command_ranges}")
remaining_dist = torch.clip(0.625 * self.cfg.terrain.terrain_length - torch.norm(self.commands_xy_accumulation[env_ids], dim=1) * self.cfg.commands.resampling_time, 0.0)
self.commands_resampling_step[env_ids] = self.cfg.commands.resampling_time / self.dt
if self.cfg.commands.dynamic_resample_commands:
# arrive at boundary 0.625 times the width of the remaining distance
if ((self.max_episode_length - self.episode_length_buf[env_ids]) == 0).any():
raise ValueError("Some envs have zero remaining episode length during command resampling")
vel_low_bound = torch.clip(remaining_dist / ((self.max_episode_length - self.episode_length_buf[env_ids] + 1e-9) * self.dt), 0.0)
self.commands[env_ids, 0] = sample_disjoint_intervals(
env_ids,
vel_low_bound,
self.env_command_ranges["lin_vel_x"][env_ids, 0],
self.env_command_ranges["lin_vel_x"][env_ids, 1],
self.device
)
self.commands[env_ids, 1] = sample_disjoint_intervals(
env_ids,
vel_low_bound,
self.env_command_ranges["lin_vel_y"][env_ids, 0],
self.env_command_ranges["lin_vel_y"][env_ids, 1],
self.device
)
if self.cfg.commands.heading_command:
r = torch.rand(len(env_ids), device=self.device)
lower = self.env_command_ranges["heading"][env_ids, 0]
upper = self.env_command_ranges["heading"][env_ids, 1]
self.commands[env_ids, 3] = (upper - lower) * r + lower
else:
r = torch.rand(len(env_ids), device=self.device)
lower = self.env_command_ranges["ang_vel_yaw"][env_ids, 0]
upper = self.env_command_ranges["ang_vel_yaw"][env_ids, 1]
self.commands[env_ids, 2] = (upper - lower) * r + lower
else:
self.commands[env_ids, 0] = sample_single_interval(
env_ids,
self.env_command_ranges["lin_vel_x"][env_ids, 0],
self.env_command_ranges["lin_vel_x"][env_ids, 1],
self.device
)
self.commands[env_ids, 1] = sample_single_interval(
env_ids,
self.env_command_ranges["lin_vel_y"][env_ids, 0],
self.env_command_ranges["lin_vel_y"][env_ids, 1],
self.device
)
if self.cfg.commands.heading_command:
self.commands[env_ids, 3] = sample_single_interval(
env_ids,
self.env_command_ranges["heading"][env_ids, 0],
self.env_command_ranges["heading"][env_ids, 1],
self.device
)
else:
self.commands[env_ids, 2] = sample_single_interval(
env_ids,
self.env_command_ranges["ang_vel_yaw"][env_ids, 0],
self.env_command_ranges["ang_vel_yaw"][env_ids, 1],
self.device
)
# set small commands to zero
self.commands[env_ids, :2] *= (torch.norm(self.commands[env_ids, :2], dim=1) > 0.2).unsqueeze(1)
rand_prob = torch.rand(len(env_ids), device=self.device)
min_prob, max_prob = 0.0, 0.0
# set limitation lin vel
if self.limit_vel_prob > 0.0:
max_prob += self.limit_vel_prob
lim_mask = (rand_prob >= min_prob) * (rand_prob < max_prob)
lim_env_ids = env_ids[lim_mask]
if len(lim_env_ids) > 0:
change_lim_env_ids = lim_env_ids
if self.cfg.commands.limit_vel_invert_when_continuous:
was_limited = self.last_is_limit_vel[lim_env_ids]
invert_env_ids = lim_env_ids[was_limited]
self.commands[invert_env_ids, 0] *= -1.0
self.commands[invert_env_ids, 1] *= -1.0
self.commands[invert_env_ids, 2] *= -1.0
change_lim_env_ids = lim_env_ids[~was_limited]
vel_idx = torch.randint(0, self.limit_vel_comb.shape[0], (len(change_lim_env_ids),), device=self.device)
lin_vel_x_lim = torch.where(
self.limit_vel_comb[vel_idx, 0] == -1,
self.env_command_ranges["lin_vel_x"][change_lim_env_ids, 0],
self.env_command_ranges["lin_vel_x"][change_lim_env_ids, 1],
)
lin_vel_x_lim[self.limit_vel_comb[vel_idx, 0] == 0] = 0.0
lin_vel_y_lim = torch.where(
self.limit_vel_comb[vel_idx, 1] == -1,
self.env_command_ranges["lin_vel_y"][change_lim_env_ids, 0],
self.env_command_ranges["lin_vel_y"][change_lim_env_ids, 1]
)
lin_vel_y_lim[self.limit_vel_comb[vel_idx, 1] == 0] = 0.0
ang_vel_z_lim = torch.where(
self.limit_vel_comb[vel_idx, 2] == -1,
self.env_command_ranges["ang_vel_yaw"][change_lim_env_ids, 0],
self.env_command_ranges["ang_vel_yaw"][change_lim_env_ids, 1]
)
ang_vel_z_lim[self.limit_vel_comb[vel_idx, 2] == 0] = 0.0
self.commands[change_lim_env_ids, 0] = lin_vel_x_lim
self.commands[change_lim_env_ids, 1] = lin_vel_y_lim
self.commands[change_lim_env_ids, 2] = ang_vel_z_lim
if self.cfg.commands.heading_command and self.cfg.commands.stop_heading_at_limit:
self.stop_heading[lim_env_ids] = True # stop heading to current heading
self.last_is_limit_vel[env_ids] = False
self.last_is_limit_vel[lim_env_ids] = True
else:
self.last_is_limit_vel[env_ids] = False
min_prob += self.limit_vel_prob
# set all commands to zero with some probability
if self.cfg.commands.zero_command_curriculum is not None:
self.zero_command_proba = self.get_current_scale(self.cfg.commands.zero_command_curriculum)
if self.zero_command_proba > 0.0:
max_prob += self.zero_command_proba
next_resampling_step = torch.clip(
self.max_episode_length - self.episode_length_buf[env_ids] - (remaining_dist / (0.8 * self.max_lin_vel * self.dt + 1e-9)),
min=0.0,
max=self.cfg.commands.resampling_time / self.dt,
)
zero_mask = (rand_prob >= min_prob) * (rand_prob < max_prob) * (next_resampling_step > 0.0)
zero_env_ids = env_ids[zero_mask]
if len(zero_env_ids) > 0:
self.commands[zero_env_ids, :2] = 0.0
self.commands_resampling_step[zero_env_ids] = next_resampling_step[zero_mask]
if self.cfg.commands.limit_ang_vel_at_zero_command_prob > 0.0:
ang_vel_rand = torch.rand(len(zero_env_ids), device=self.device) # independent distribution
add_ang_mask = ang_vel_rand < self.cfg.commands.limit_ang_vel_at_zero_command_prob
add_ang_env_ids = zero_env_ids[add_ang_mask]
if len(add_ang_env_ids) > 0:
direction_rand = torch.rand(len(add_ang_env_ids), device=self.device)
self.commands[add_ang_env_ids, 2] = torch.where(
direction_rand < 0.5,
self.env_command_ranges["ang_vel_yaw"][add_ang_env_ids, 0],
self.env_command_ranges["ang_vel_yaw"][add_ang_env_ids, 1]
)
if self.cfg.commands.heading_command:
self.stop_heading[add_ang_env_ids] = True
min_prob += self.zero_command_proba
# turn over zero command time
if self.cfg.init_state.turn_over and (self.turn_over_timer[env_ids] > 0).any():
zero_mask = self.turn_over_timer[env_ids] > 0
zero_env_ids = env_ids[zero_mask]
self.commands[zero_env_ids, :3] = 0.0
self.stop_heading[zero_env_ids] = True
self.commands_xy_accumulation[env_ids] += self.commands[env_ids, :2]
def _compute_torques(self, actions):
""" Compute torques from actions.
Actions can be interpreted as position or velocity targets given to a PD controller, or directly as scaled torques.
[NOTE]: torques must have the same dimension as the number of DOFs, even if some DOFs are not actuated.
Args:
actions (torch.Tensor): Actions
Returns:
[torch.Tensor]: Torques sent to the simulation
"""
#pd controller
actions_scaled = actions * self.cfg.control.action_scale
control_type = self.cfg.control.control_type
p_gains = self.p_gains * self.p_gains_multiplier
d_gains = self.d_gains * self.d_gains_multiplier
if control_type=="P":
torques = p_gains*(actions_scaled + self.default_dof_pos - self.dof_pos + self.motor_zero_offsets) - d_gains*self.dof_vel
elif control_type=="V":
torques = p_gains*(actions_scaled - self.dof_vel) - d_gains*(self.dof_vel - self.last_dof_vel)/self.sim_params.dt
elif control_type=="T":
torques = actions_scaled
else:
raise NameError(f"Unknown controller type: {control_type}")
return torch.clip(torques, -self.torque_limits, self.torque_limits)
def _reset_dofs(self, env_ids):
""" Resets DOF position and velocities of selected environmments
Positions are randomly selected within 0.5:1.5 x default positions.
Velocities are set to zero.
Args:
env_ids (List[int]): Environemnt ids
"""
self.dof_pos[env_ids] = self.default_dof_pos * torch_rand_float(0.5, 1.5, (len(env_ids), self.num_dof), device=self.device)
self.dof_vel[env_ids] = 0.
env_ids_int32 = env_ids.to(dtype=torch.int32)
self.gym.set_dof_state_tensor_indexed(self.sim,
gymtorch.unwrap_tensor(self.dof_state),
gymtorch.unwrap_tensor(env_ids_int32), len(env_ids_int32))
def _reset_root_states(self, env_ids):
""" Resets ROOT states position and velocities of selected environmments
Sets base position based on the curriculum
Selects randomized base velocities within -0.5:0.5 [m/s, rad/s]
Args:
env_ids (List[int]): Environemnt ids
"""
if self.cfg.init_state.turn_over:
self.turn_over_timer[env_ids] = 0.0
# base position
random_yaw = torch_rand_float(-np.pi, np.pi, (len(env_ids), 1), device=self.device).squeeze(1)
def get_quat(target_yaws, roll: float):
roll_tensor = torch.full((len(target_yaws),), roll, device=self.device)
pitch_tensor = torch.zeros((len(target_yaws),), device=self.device)
quat = quat_from_euler_xyz(roll_tensor, pitch_tensor, target_yaws)
return quat
base_init_state = self.base_init_state.reshape(1, -1).repeat(len(env_ids), 1)
if self.cfg.init_state.turn_over:
rand_prob = torch.rand(len(env_ids), device=self.device)
proportions = self.cfg.init_state.turn_over_proportions
init_heights = self.cfg.init_state.turn_over_init_heights
min_prob, max_prob = 0.0, proportions[0]
back_mask = (rand_prob >= min_prob) * (rand_prob < max_prob) # backflip
if back_mask.any():
heights = torch_rand_float(init_heights['backflip'][0], init_heights['backflip'][1], (torch.sum(back_mask), 1), device=self.device).squeeze(1)
base_init_state[back_mask, 2] = heights # z
base_init_state[back_mask, 3:7] = get_quat(random_yaw[back_mask], np.pi)
if self.cfg.init_state.turn_over:
self.turn_over_timer[env_ids[back_mask]] = self.cfg.commands.turn_over_zero_time['backflip']
min_prob = max_prob
max_prob += proportions[1]
side_mask = (rand_prob >= min_prob) * (rand_prob < max_prob) # sideflip
if side_mask.any():
side_ids = torch.nonzero(side_mask, as_tuple=False).flatten()
heights = torch_rand_float(init_heights['sideflip'][0], init_heights['sideflip'][1], (len(side_ids), 1), device=self.device).squeeze(1)
base_init_state[side_mask, 2] = heights # z
side_rand_prob = torch.rand(len(side_ids), device=self.device)
pos_side_mask = side_rand_prob < 0.5
neg_side_mask = ~pos_side_mask
if pos_side_mask.any():
pos_ids = side_ids[pos_side_mask]
base_init_state[pos_ids, 3:7] = get_quat(random_yaw[pos_ids], np.pi/2)
if neg_side_mask.any():
neg_ids = side_ids[neg_side_mask]
base_init_state[neg_ids, 3:7] = get_quat(random_yaw[neg_ids], -np.pi/2)
if self.cfg.init_state.turn_over:
self.turn_over_timer[env_ids[side_mask]] = self.cfg.commands.turn_over_zero_time['sideflip']
min_prob = max_prob
max_prob += proportions[2]
noflip_mask = (rand_prob >= min_prob) * (rand_prob < max_prob) # noflip
if noflip_mask.any():
noflip_indices = torch.nonzero(noflip_mask, as_tuple=False).flatten()
base_init_state[noflip_mask, 3:7] = get_quat(random_yaw[noflip_indices], 0.0)
else:
base_init_state[:, 3:7] = get_quat(random_yaw, 0.0)
if self.custom_origins:
self.root_states[env_ids] = base_init_state
self.root_states[env_ids, :3] += self.env_origins[env_ids]
self.root_states[env_ids, :2] += torch_rand_float(-1., 1., (len(env_ids), 2), device=self.device) # xy position within 1m of the center
else:
self.root_states[env_ids] = base_init_state
self.root_states[env_ids, :3] += self.env_origins[env_ids]
# base velocities
self.root_states[env_ids, 7:13] = torch_rand_float(-0.5, 0.5, (len(env_ids), 6), device=self.device) # [7:10]: lin vel, [10:13]: ang vel
env_ids_int32 = env_ids.to(dtype=torch.int32)
self.gym.set_actor_root_state_tensor_indexed(self.sim,
gymtorch.unwrap_tensor(self.root_states),
gymtorch.unwrap_tensor(env_ids_int32), len(env_ids_int32))
def _push_robots(self):
""" Random pushes the robots. Emulates an impulse by setting a randomized base velocity.
"""
env_ids = torch.arange(self.num_envs, device=self.device)
push_env_ids = env_ids[self.episode_length_buf[env_ids] % int(self.cfg.domain_rand.push_interval) == 0]
if len(push_env_ids) == 0:
return
max_vel = self.cfg.domain_rand.max_push_vel_xy
max_push_ang = self.cfg.domain_rand.max_push_ang_vel
self.root_states[:, 7:9] = torch_rand_float(-max_vel, max_vel, (self.num_envs, 2), device=self.device) # lin vel x/y
self.root_states[:, 10:13] = torch_rand_float(-max_push_ang, max_push_ang, (self.num_envs, 3), device=self.device) # ang vel x/y/z
env_ids_int32 = push_env_ids.to(dtype=torch.int32)
self.gym.set_actor_root_state_tensor_indexed(self.sim,
gymtorch.unwrap_tensor(self.root_states),
gymtorch.unwrap_tensor(env_ids_int32), len(env_ids_int32))
def update_command_curriculum(self, env_ids):
""" Implements a curriculum of increasing commands
Args:
env_ids (List[int]): ids of environments being reset
"""
# If the tracking reward is above 80% of the maximum, increase the range of commands
if torch.mean(self.episode_sums["tracking_lin_vel"][env_ids]) / self.max_episode_length > 0.8 * self.reward_scales["tracking_lin_vel"]:
self.command_ranges["lin_vel_x"][0] = np.clip(self.command_ranges["lin_vel_x"][0] - 0.5, -self.cfg.commands.max_curriculum, 0.)
self.command_ranges["lin_vel_x"][1] = np.clip(self.command_ranges["lin_vel_x"][1] + 0.5, 0., self.cfg.commands.max_curriculum)
def _get_noise_scale_vec(self, cfg):
""" Sets a vector used to scale the noise added to the observations.
[NOTE]: Must be adapted when changing the observations structure
Args:
cfg (Dict): Environment config file
Returns:
[torch.Tensor]: Vector of scales used to multiply a uniform distribution in [-1, 1]
"""
noise_vec = torch.zeros_like(self.obs_buf[0])
self.add_noise = self.cfg.noise.add_noise
noise_scales = self.cfg.noise.noise_scales
noise_level = self.cfg.noise.noise_level
noise_vec[:3] = noise_scales.lin_vel * noise_level * self.obs_scales.lin_vel
noise_vec[3:6] = noise_scales.ang_vel * noise_level * self.obs_scales.ang_vel
noise_vec[6:9] = noise_scales.gravity * noise_level
noise_vec[9:12] = 0. # commands
noise_vec[12:12+self.num_actions] = noise_scales.dof_pos * noise_level * self.obs_scales.dof_pos
noise_vec[12+self.num_actions:12+2*self.num_actions] = noise_scales.dof_vel * noise_level * self.obs_scales.dof_vel
noise_vec[12+2*self.num_actions:12+3*self.num_actions] = 0. # previous actions
return noise_vec
#----------------------------------------
def _init_buffers(self):
""" Initialize torch tensors which will contain simulation states and processed quantities
"""
# get gym GPU state tensors
actor_root_state = self.gym.acquire_actor_root_state_tensor(self.sim)
dof_state_tensor = self.gym.acquire_dof_state_tensor(self.sim)
net_contact_forces = self.gym.acquire_net_contact_force_tensor(self.sim)
rigid_body_state = self.gym.acquire_rigid_body_state_tensor(self.sim)
self.gym.refresh_dof_state_tensor(self.sim)
self.gym.refresh_actor_root_state_tensor(self.sim)
self.gym.refresh_net_contact_force_tensor(self.sim)
self.gym.refresh_rigid_body_state_tensor(self.sim)
# create some wrapper tensors for different slices
self.root_states = gymtorch.wrap_tensor(actor_root_state)
self.dof_state = gymtorch.wrap_tensor(dof_state_tensor)
self.dof_pos = self.dof_state.view(self.num_envs, self.num_dof, 2)[..., 0]
self.dof_vel = self.dof_state.view(self.num_envs, self.num_dof, 2)[..., 1]
self.base_quat = self.root_states[:, 3:7]
self.rpy = get_euler_xyz_in_tensor(self.base_quat)
self.base_pos = self.root_states[:self.num_envs, 0:3]
self.contact_forces = gymtorch.wrap_tensor(net_contact_forces).view(self.num_envs, -1, 3) # shape: num_envs, num_bodies, xyz axis
self.rigid_body_states = gymtorch.wrap_tensor(rigid_body_state)
if self.cfg.terrain.measure_heights:
self.height_points = self._init_height_points()
x_points = self.height_points[0, :, 0]
y_points = self.height_points[0, :, 1]
x_mask = (x_points >= -0.2) & (x_points <= 0.2) # 0.4m length
y_mask = (y_points >= -0.15) & (y_points <= 0.15) # 0.3m width
self.base_height_scan_mask = (x_mask & y_mask).float()
self.num_base_height_scan_points = self.base_height_scan_mask.sum()
assert self.num_base_height_scan_points > 0, "No height scan points within the specified area."
self.measured_heights = 0
# initialize some data used later on
self.common_step_counter = 0
self.extras = {}
self.noise_scale_vec = self._get_noise_scale_vec(self.cfg)
self.gravity_vec = to_torch(get_axis_params(-1., self.up_axis_idx), device=self.device).repeat((self.num_envs, 1))
self.forward_vec = to_torch([1., 0., 0.], device=self.device).repeat((self.num_envs, 1))
self.torques = torch.zeros(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.p_gains = torch.zeros(self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.d_gains = torch.zeros(self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.actions = torch.zeros(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.last_actions = torch.zeros(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.last_dof_vel = torch.zeros_like(self.dof_vel)
self.last_root_vel = torch.zeros_like(self.root_states[:, 7:13])
self.commands = torch.zeros(self.num_envs, self.cfg.commands.num_commands, dtype=torch.float, device=self.device, requires_grad=False) # x vel, y vel, yaw vel, heading
self.commands_scale = torch.tensor([self.obs_scales.lin_vel, self.obs_scales.lin_vel, self.obs_scales.ang_vel], device=self.device, requires_grad=False,) # TODO change this
self.commands_resampling_step = torch.zeros(self.num_envs, dtype=torch.float, device=self.device, requires_grad=False)
self.commands_xy_accumulation = torch.zeros(self.num_envs, 2, dtype=torch.float, device=self.device, requires_grad=False)
self.zero_command_proba = 0.0
self.feet_air_time = torch.zeros(self.num_envs, self.feet_indices.shape[0], dtype=torch.float, device=self.device, requires_grad=False)
self.last_contacts = torch.zeros(self.num_envs, len(self.feet_indices), dtype=torch.bool, device=self.device, requires_grad=False)
self.base_lin_vel = quat_rotate_inverse(self.base_quat, self.root_states[:, 7:10])
self.base_ang_vel = quat_rotate_inverse(self.base_quat, self.root_states[:, 10:13])
self.projected_gravity = quat_rotate_inverse(self.base_quat, self.gravity_vec)
self.max_move_distance = torch.zeros(self.num_envs, dtype=torch.float, device=self.device, requires_grad=False)
self.stop_heading = torch.zeros(self.num_envs, dtype=torch.bool, device=self.device, requires_grad=False)
self.last_is_limit_vel = torch.zeros(self.num_envs, dtype=torch.bool, device=self.device, requires_grad=False)
self.motor_strengths = torch.ones(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.limit_vel_prob = self.cfg.commands.limit_vel_prob
self.limit_vel_comb = torch.tensor(list(product(
self.cfg.commands.limit_vel["lin_vel_x"],
self.cfg.commands.limit_vel["lin_vel_y"],
self.cfg.commands.limit_vel["ang_vel_yaw"]
)), device=self.device, requires_grad=False)
self.last_robot_props_update_step = torch.zeros(self.num_envs, dtype=torch.long, device=self.device, requires_grad=False)
self.turn_over_timer = torch.zeros(self.num_envs, dtype=torch.float, device=self.device, requires_grad=False)
self.env_command_ranges = {
'lin_vel_x': torch.tensor(self.command_ranges['lin_vel_x'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
'lin_vel_y': torch.tensor(self.command_ranges['lin_vel_y'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
'ang_vel_yaw': torch.tensor(self.command_ranges['ang_vel_yaw'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
'heading': torch.tensor(self.command_ranges['heading'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
}
self._update_env_command_ranges()
# joint positions offsets and PD gains
self.default_dof_pos = torch.zeros(self.num_dof, dtype=torch.float, device=self.device, requires_grad=False)
for i in range(self.num_dofs):
name = self.dof_names[i]
angle = self.cfg.init_state.default_joint_angles[name]
self.default_dof_pos[i] = angle
found = False
for dof_name in self.cfg.control.stiffness.keys():
if dof_name in name:
self.p_gains[i] = self.cfg.control.stiffness[dof_name]
self.d_gains[i] = self.cfg.control.damping[dof_name]
found = True
if not found:
self.p_gains[i] = 0.
self.d_gains[i] = 0.
if self.cfg.control.control_type in ["P", "V"]:
print(f"PD gain of joint {name} were not defined, setting them to zero")
self.default_dof_pos = self.default_dof_pos.unsqueeze(0)
def _update_env_command_ranges(self):
""" Update environment-wise command ranges based on current command ranges and terrain type """
if not hasattr(self, 'terrain_ids'):
self.env_command_ranges = {
'lin_vel_x': torch.tensor(self.command_ranges['lin_vel_x'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
'lin_vel_y': torch.tensor(self.command_ranges['lin_vel_y'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
'ang_vel_yaw': torch.tensor(self.command_ranges['ang_vel_yaw'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
'heading': torch.tensor(self.command_ranges['heading'], device=self.device, requires_grad=False).repeat(self.num_envs, 1),
}
return
for terrain_id, terrain_command_ranges in enumerate(self.cfg.commands.terrain_max_command_ranges):
env_ids = (self.terrain_ids == terrain_id).nonzero(as_tuple=False).flatten()
if len(env_ids) == 0:
continue
self.env_command_ranges['lin_vel_x'][env_ids, 0] = max(
terrain_command_ranges['lin_vel_x'][0],
self.command_ranges['lin_vel_x'][0],
)
self.env_command_ranges['lin_vel_x'][env_ids, 1] = min(
terrain_command_ranges['lin_vel_x'][1],
self.command_ranges['lin_vel_x'][1]
)
self.env_command_ranges['lin_vel_y'][env_ids, 0] = max(
terrain_command_ranges['lin_vel_y'][0],
self.command_ranges['lin_vel_y'][0]
)
self.env_command_ranges['lin_vel_y'][env_ids, 1] = min(
terrain_command_ranges['lin_vel_y'][1],
self.command_ranges['lin_vel_y'][1]
)
self.env_command_ranges['ang_vel_yaw'][env_ids, 0] = max(
terrain_command_ranges['ang_vel_yaw'][0],
self.command_ranges['ang_vel_yaw'][0]
)
self.env_command_ranges['ang_vel_yaw'][env_ids, 1] = min(
terrain_command_ranges['ang_vel_yaw'][1],
self.command_ranges['ang_vel_yaw'][1]
)
if self.cfg.commands.heading_command:
self.env_command_ranges['heading'][env_ids, 0] = max(
terrain_command_ranges['heading'][0],
self.command_ranges['heading'][0]
)
self.env_command_ranges['heading'][env_ids, 1] = min(
terrain_command_ranges['heading'][1],
self.command_ranges['heading'][1]
)
def _prepare_reward_function(self):
""" Prepares a list of reward functions, whcih will be called to compute the total reward.
Looks for self._reward_<REWARD_NAME>, where <REWARD_NAME> are names of all non zero reward scales in the cfg.
"""
# remove zero scales + multiply non-zero ones by dt
def update_scales(scales):
for key in list(scales.keys()):
scale = scales[key]
if scale==0:
scales.pop(key)
else:
scales[key] *= self.dt
update_scales(self.reward_scales)
if self.cfg.init_state.turn_over:
update_scales(self.reward_turn_over_scales)
# prepare list of functions
self.reward_functions = []
self.reward_names = []
names = set()
names.update(list(self.reward_scales.keys()))
if self.cfg.init_state.turn_over:
names.update(list(self.reward_turn_over_scales.keys()))
for name in names:
if name=="termination":
continue
self.reward_names.append(name)
name = '_reward_' + name
self.reward_functions.append(getattr(self, name))
# reward episode sums
self.episode_sums = {name: torch.zeros(self.num_envs, dtype=torch.float, device=self.device, requires_grad=False)
for name in names}
def _create_ground_plane(self):
""" Adds a ground plane to the simulation, sets friction and restitution based on the cfg.
"""
plane_params = gymapi.PlaneParams()
plane_params.normal = gymapi.Vec3(0.0, 0.0, 1.0)
plane_params.static_friction = self.cfg.terrain.static_friction
plane_params.dynamic_friction = self.cfg.terrain.dynamic_friction
plane_params.restitution = self.cfg.terrain.restitution
self.gym.add_ground(self.sim, plane_params)
def _create_envs(self):
""" Creates environments:
1. loads the robot URDF/MJCF asset,
2. For each environment
2.1 creates the environment,
2.2 calls DOF and Rigid shape properties callbacks,
2.3 create actor with these properties and add them to the env
3. Store indices of different bodies of the robot
"""
asset_path = self.cfg.asset.file.format(LEGGED_GYM_ROOT_DIR=LEGGED_GYM_ROOT_DIR)
asset_root = os.path.dirname(asset_path)
asset_file = os.path.basename(asset_path)
asset_options = gymapi.AssetOptions()
asset_options.default_dof_drive_mode = self.cfg.asset.default_dof_drive_mode
asset_options.collapse_fixed_joints = self.cfg.asset.collapse_fixed_joints
asset_options.replace_cylinder_with_capsule = self.cfg.asset.replace_cylinder_with_capsule
asset_options.flip_visual_attachments = self.cfg.asset.flip_visual_attachments
asset_options.fix_base_link = self.cfg.asset.fix_base_link
asset_options.density = self.cfg.asset.density
asset_options.angular_damping = self.cfg.asset.angular_damping
asset_options.linear_damping = self.cfg.asset.linear_damping
asset_options.max_angular_velocity = self.cfg.asset.max_angular_velocity
asset_options.max_linear_velocity = self.cfg.asset.max_linear_velocity
asset_options.armature = self.cfg.asset.armature
asset_options.thickness = self.cfg.asset.thickness
asset_options.disable_gravity = self.cfg.asset.disable_gravity
self.robot_asset = self.gym.load_asset(self.sim, asset_root, asset_file, asset_options)
self.num_dof = self.gym.get_asset_dof_count(self.robot_asset)
self.num_bodies = self.gym.get_asset_rigid_body_count(self.robot_asset)
dof_props_asset = self.gym.get_asset_dof_properties(self.robot_asset)
rigid_shape_props_asset = self.gym.get_asset_rigid_shape_properties(self.robot_asset)
# save body names from the asset
body_names = self.gym.get_asset_rigid_body_names(self.robot_asset)
self.dof_names = self.gym.get_asset_dof_names(self.robot_asset)
self.num_bodies = len(body_names)
self.num_dofs = len(self.dof_names)
feet_names = [s for s in body_names if self.cfg.asset.foot_name in s]
hip_names = [s for s in self.dof_names if 'hip' in s]
penalized_contact_names = []
for name in self.cfg.asset.penalize_contacts_on:
penalized_contact_names.extend([s for s in body_names if name in s])
termination_contact_names = []
for name in self.cfg.asset.terminate_after_contacts_on:
termination_contact_names.extend([s for s in body_names if name in s])
base_init_state_list = self.cfg.init_state.pos + self.cfg.init_state.rot + self.cfg.init_state.lin_vel + self.cfg.init_state.ang_vel
self.base_init_state = to_torch(base_init_state_list, device=self.device, requires_grad=False)
start_pose = gymapi.Transform()
start_pose.p = gymapi.Vec3(*self.base_init_state[:3])
# domain rand
self.motor_zero_offsets = torch.zeros(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.p_gains_multiplier = torch.ones(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
self.d_gains_multiplier = torch.ones(self.num_envs, self.num_actions, dtype=torch.float, device=self.device, requires_grad=False)
if self.cfg.rewards.dynamic_sigma:
self.dynamic_sigma_cfg = self.cfg.rewards.dynamic_sigma
self.terrain_max_sigmas = torch.tensor(self.dynamic_sigma_cfg["max_sigma"], device=self.device, requires_grad=False)
self._get_env_origins()
env_lower = gymapi.Vec3(0., 0., 0.)
env_upper = gymapi.Vec3(0., 0., 0.)
self.actor_handles = []
self.envs = []
for i in range(self.num_envs):
# create env instance
env_handle = self.gym.create_env(self.sim, env_lower, env_upper, int(np.sqrt(self.num_envs)))
pos = self.env_origins[i].clone()
pos[:2] += torch_rand_float(-1., 1., (2,1), device=self.device).squeeze(1)
start_pose.p = gymapi.Vec3(*pos)
rigid_shape_props = self._process_rigid_shape_props(rigid_shape_props_asset, i)
self.gym.set_asset_rigid_shape_properties(self.robot_asset, rigid_shape_props)
actor_handle = self.gym.create_actor(env_handle, self.robot_asset, start_pose, self.cfg.asset.name, i, self.cfg.asset.self_collisions, 0)
dof_props = self._process_dof_props(dof_props_asset, i)
self.gym.set_actor_dof_properties(env_handle, actor_handle, dof_props)
body_props = self.gym.get_actor_rigid_body_properties(env_handle, actor_handle)
if i == 0:
self.default_body_props = self.gym.get_actor_rigid_body_properties(env_handle, actor_handle)
body_props = self._process_rigid_body_props(body_props, i)
self.gym.set_actor_rigid_body_properties(env_handle, actor_handle, body_props, recomputeInertia=True)
self.envs.append(env_handle)
self.actor_handles.append(actor_handle)
self.feet_indices = torch.zeros(len(feet_names), dtype=torch.long, device=self.device, requires_grad=False)
for i in range(len(feet_names)):
self.feet_indices[i] = self.gym.find_actor_rigid_body_handle(self.envs[0], self.actor_handles[0], feet_names[i])
self.hip_indices = torch.zeros(len(hip_names), dtype=torch.long, device=self.device, requires_grad=False)
for i in range(len(hip_names)):
self.hip_indices[i] = self.gym.find_actor_dof_handle(self.envs[0], self.actor_handles[0], hip_names[i])
self.penalised_contact_indices = torch.zeros(len(penalized_contact_names), dtype=torch.long, device=self.device, requires_grad=False)
for i in range(len(penalized_contact_names)):
self.penalised_contact_indices[i] = self.gym.find_actor_rigid_body_handle(self.envs[0], self.actor_handles[0], penalized_contact_names[i])
self.termination_contact_indices = torch.zeros(len(termination_contact_names), dtype=torch.long, device=self.device, requires_grad=False)
for i in range(len(termination_contact_names)):
self.termination_contact_indices[i] = self.gym.find_actor_rigid_body_handle(self.envs[0], self.actor_handles[0], termination_contact_names[i])
def _get_env_origins(self):
""" Sets environment origins. On rough terrain the origins are defined by the terrain platforms.
Otherwise create a grid.
"""
if self.cfg.terrain.mesh_type in ["heightfield", "trimesh"]:
self.custom_origins = True
self.env_origins = torch.zeros(self.num_envs, 3, device=self.device, requires_grad=False)
# put robots at the origins defined by the terrain
max_init_level = self.cfg.terrain.max_init_terrain_level
if not self.cfg.terrain.curriculum:
max_init_level = self.cfg.terrain.num_rows - 1
# random choice terrain levels and types for each env
# self.terrain_levels = torch.randint(0, max_init_level+1, (self.num_envs,), device=self.device)
# self.terrain_types = torch.randint(0, self.cfg.terrain.num_cols, (self.num_envs,), device=self.device)
# levels and types in a round robin manner
self.terrain_levels = torch.fmod(torch.arange(self.num_envs, device=self.device), max_init_level + 1)
self.terrain_types = torch.div(torch.arange(self.num_envs, device=self.device), (self.num_envs / self.cfg.terrain.num_cols), rounding_mode="floor").to(torch.long)
self.terrain_cols2id = torch.tensor(self.terrain.cols2id, device=self.device)
if len(self.terrain_cols2id):
self.terrain_ids = self.terrain_cols2id[self.terrain_types]
self.max_terrain_level = self.cfg.terrain.num_rows
self.terrain_origins = torch.from_numpy(self.terrain.env_origins).to(self.device).to(torch.float)
self.env_origins[:] = self.terrain_origins[self.terrain_levels, self.terrain_types]
else:
self.custom_origins = False
self.env_origins = torch.zeros(self.num_envs, 3, device=self.device, requires_grad=False)
# create a grid of robots
num_cols = np.floor(np.sqrt(self.num_envs))
num_rows = np.ceil(self.num_envs / num_cols)
xx, yy = torch.meshgrid(torch.arange(num_rows), torch.arange(num_cols))
spacing = self.cfg.env.env_spacing
self.env_origins[:, 0] = spacing * xx.flatten()[:self.num_envs]
self.env_origins[:, 1] = spacing * yy.flatten()[:self.num_envs]
self.env_origins[:, 2] = 0.
def _parse_cfg(self, cfg):
self.dt = self.cfg.control.decimation * self.sim_params.dt
self.obs_scales = self.cfg.normalization.obs_scales
self.reward_scales = class_to_dict(self.cfg.rewards.scales)
self.reward_turn_over_scales = class_to_dict(self.cfg.rewards.turn_over_scales)
self.command_ranges = class_to_dict(self.cfg.commands.ranges)
self.max_lin_vel = max(abs(self.command_ranges["lin_vel_x"][0]), abs(self.command_ranges["lin_vel_x"][1]),
abs(self.command_ranges["lin_vel_y"][0]), abs(self.command_ranges["lin_vel_y"][1]))
self.cfg.commands.command_range_curriculum = sorted(self.cfg.commands.command_range_curriculum, key=lambda x: x['iter'], reverse=True)
self.max_episode_length_s = self.cfg.env.episode_length_s
self.max_episode_length = np.ceil(self.max_episode_length_s / self.dt)
self.cfg.domain_rand.push_interval = np.ceil(self.cfg.domain_rand.push_interval_s / self.dt)
def _create_heightfield(self):
""" Adds a heightfield terrain to the simulation, sets parameters based on the cfg.
"""
hf_params = gymapi.HeightFieldParams()
hf_params.column_scale = self.terrain.cfg.horizontal_scale
hf_params.row_scale = self.terrain.cfg.horizontal_scale
hf_params.vertical_scale = self.terrain.cfg.vertical_scale
hf_params.nbRows = self.terrain.tot_cols
hf_params.nbColumns = self.terrain.tot_rows
hf_params.transform.p.x = -self.terrain.cfg.border_size
hf_params.transform.p.y = -self.terrain.cfg.border_size
hf_params.transform.p.z = 0.0
hf_params.static_friction = self.cfg.terrain.static_friction
hf_params.dynamic_friction = self.cfg.terrain.dynamic_friction
hf_params.restitution = self.cfg.terrain.restitution
self.gym.add_heightfield(self.sim, self.terrain.heightsamples, hf_params)
self.height_samples = torch.tensor(self.terrain.heightsamples).view(self.terrain.tot_rows, self.terrain.tot_cols).to(self.device)
def _create_trimesh(self):
""" Adds a triangle mesh terrain to the simulation, sets parameters based on the cfg.
# """
tm_params = gymapi.TriangleMeshParams()
tm_params.nb_vertices = self.terrain.vertices.shape[0]
tm_params.nb_triangles = self.terrain.triangles.shape[0]
tm_params.transform.p.x = -self.terrain.cfg.border_size
tm_params.transform.p.y = -self.terrain.cfg.border_size
tm_params.transform.p.z = 0.0
tm_params.static_friction = self.cfg.terrain.static_friction
tm_params.dynamic_friction = self.cfg.terrain.dynamic_friction
tm_params.restitution = self.cfg.terrain.restitution
self.gym.add_triangle_mesh(self.sim, self.terrain.vertices.flatten(order='C'), self.terrain.triangles.flatten(order='C'), tm_params)
self.height_samples = torch.tensor(self.terrain.heightsamples).view(self.terrain.tot_rows, self.terrain.tot_cols).to(self.device)
def _update_terrain_curriculum(self, env_ids):
""" Implements the game-inspired curriculum.
Args:
env_ids (List[int]): ids of environments being reset
"""
# Implement Terrain curriculum
if not self.init_done or self.cfg.terrain.mesh_type == 'plane':
# don't change on initial reset
return
# distance = torch.norm(self.root_states[env_ids, :2] - self.env_origins[env_ids, :2], dim=1)
distance = self.max_move_distance[env_ids]
# robots that walked far enough progress to harder terains
move_up = distance > self.terrain.env_length / 2
if self.cfg.terrain.move_down_by_accumulated_xy_command:
move_down = (distance < torch.norm(self.commands_xy_accumulation[env_ids], dim=1) * (self.cfg.commands.resampling_time * (1 - self.zero_command_proba)) * 0.5) * ~move_up
else:
# robots that walked less than half of their required distance go to simpler terrains
move_down = (distance < torch.norm(self.commands[env_ids, :2], dim=1) * self.max_episode_length_s * 0.5) * ~move_up
self.terrain_levels[env_ids] += 1 * move_up - 1 * move_down
# Robots that solve the last level are sent to a random one
self.terrain_levels[env_ids] = torch.where(self.terrain_levels[env_ids]>=self.max_terrain_level,
torch.randint_like(self.terrain_levels[env_ids], self.max_terrain_level),
torch.clip(self.terrain_levels[env_ids], 0)) # (the minumum level is zero)
self.env_origins[env_ids] = self.terrain_origins[self.terrain_levels[env_ids], self.terrain_types[env_ids]]
self.max_move_distance[env_ids] = 0.0
def _init_height_points(self):
""" Returns points at which the height measurments are sampled (in base frame)
Returns:
[torch.Tensor]: Tensor of shape (num_envs, self.num_height_points, 3)
"""
y = torch.tensor(self.cfg.terrain.measured_points_y, device=self.device, requires_grad=False)
x = torch.tensor(self.cfg.terrain.measured_points_x, device=self.device, requires_grad=False)
grid_x, grid_y = torch.meshgrid(x, y)
self.num_height_points = grid_x.numel()
points = torch.zeros(self.num_envs, self.num_height_points, 3, device=self.device, requires_grad=False)
points[:, :, 0] = grid_x.flatten()
points[:, :, 1] = grid_y.flatten()
return points
def _get_heights(self, env_ids=None):
""" Samples heights of the terrain at required points around each robot.
The points are offset by the base's position and rotated by the base's yaw
Args:
env_ids (List[int], optional): Subset of environments for which to return the heights. Defaults to None.
Raises:
NameError: [description]
Returns:
[type]: [description]
"""
if self.cfg.terrain.mesh_type == "plane":
return torch.zeros(self.num_envs, self.num_height_points, device=self.device, requires_grad=False)
elif self.cfg.terrain.mesh_type == "none":
raise NameError("Can't measure height with terrain mesh type 'none'")
if env_ids:
points = quat_apply_yaw(self.base_quat[env_ids].repeat(1, self.num_height_points), self.height_points[env_ids]) + (self.root_states[env_ids, :3]).unsqueeze(1)
else:
points = quat_apply_yaw(self.base_quat.repeat(1, self.num_height_points), self.height_points) + (self.root_states[:, :3]).unsqueeze(1)
points += self.terrain.cfg.border_size
points = (points / self.terrain.cfg.horizontal_scale).long()
px = points[:, :, 0].view(-1)
py = points[:, :, 1].view(-1)
px = torch.clip(px, 0, self.height_samples.shape[0] - 2)
py = torch.clip(py, 0, self.height_samples.shape[1] - 2)
heights1 = self.height_samples[px, py]
heights2 = self.height_samples[px + 1, py]
heights3 = self.height_samples[px, py + 1]
heights = torch.min(heights1, heights2)
heights = torch.min(heights, heights3)
return heights.view(self.num_envs, -1) * self.terrain.cfg.vertical_scale
#------------ reward functions----------------
def _reward_lin_vel_z(self):
# Penalize z axis base linear velocity
return torch.square(self.base_lin_vel[:, 2])
def _reward_ang_vel_xy(self):
# Penalize xy axes base angular velocity
return torch.sum(torch.square(self.base_ang_vel[:, :2]), dim=1)
def _reward_orientation(self):
# Penalize non flat base orientation
return torch.sum(torch.square(self.projected_gravity[:, :2]), dim=1)
# def _reward_base_height(self):
# # Penalize base height away from target
# base_height = self.root_states[:, 2]
# return torch.square(base_height - self.cfg.rewards.base_height_target)
def _reward_base_height(self):
# Penalize base height away from target
contact = self.contact_forces[:, self.feet_indices, 2] > 1.
if not hasattr(self, 'last_contacts2'):
self.last_contacts2 = torch.zeros_like(contact)
contact_filt = torch.logical_or(contact, self.last_contacts2) # (N, 4)
self.last_contacts2 = contact
feet_pos = self.rigid_body_states.view(self.num_envs, self.num_bodies, 13)[:, self.feet_indices, 0:3]
num_feet_contact = torch.sum(contact_filt, dim=1, keepdim=True).clamp(min=1.0) # (N, 1)
feet_contact_pos = (feet_pos * contact_filt.unsqueeze(-1)).sum(dim=1) / num_feet_contact # (N, 3)
base_pos = self.root_states[:, 0:3]
delta_pos = feet_contact_pos - base_pos
base_height = (delta_pos * self.projected_gravity).sum(1) # (N,)
rew = torch.square(base_height - self.cfg.rewards.base_height_target) * (contact_filt.sum(1) > 0)
return rew
def _reward_torques(self):
# Penalize torques
return torch.sum(torch.square(self.torques), dim=1)
def _reward_dof_vel(self):
# Penalize dof velocities
return torch.sum(torch.square(self.dof_vel), dim=1)
def _reward_dof_acc(self):
# Penalize dof accelerations
return torch.sum(torch.square((self.last_dof_vel - self.dof_vel) / self.dt), dim=1)
def _reward_action_rate(self):
# Penalize changes in actions
return torch.sum(torch.square(self.last_actions - self.actions), dim=1)
def _reward_collision(self):
# Penalize collisions on selected bodies
return torch.sum(1.*(torch.norm(self.contact_forces[:, self.penalised_contact_indices, :], dim=-1) > 0.1), dim=1)
def _reward_termination(self):
# Terminal reward / penalty
return self.reset_buf * ~self.time_out_buf
def _reward_dof_pos_limits(self):
# Penalize dof positions too close to the limit
out_of_limits = -(self.dof_pos - self.dof_pos_limits[:, 0]).clip(max=0.) # lower limit
out_of_limits += (self.dof_pos - self.dof_pos_limits[:, 1]).clip(min=0.)
return torch.sum(out_of_limits, dim=1)
def _reward_dof_vel_limits(self):
# Penalize dof velocities too close to the limit
# clip to max error = 1 rad/s per joint to avoid huge penalties
return torch.sum((torch.abs(self.dof_vel) - self.dof_vel_limits*self.cfg.rewards.soft_dof_vel_limit).clip(min=0., max=1.), dim=1)
def _reward_torque_limits(self):
# penalize torques too close to the limit
return torch.sum((torch.abs(self.torques) - self.torque_limits*self.cfg.rewards.soft_torque_limit).clip(min=0.), dim=1)
def _get_dynamic_sigma(self, target_vel_abs, v_min, v_max):
# compute dynamic sigma based on terrain level
default_sigma = self.cfg.rewards.tracking_sigma
if not self.cfg.terrain.curriculum or self.cfg.rewards.dynamic_sigma is None or not hasattr(self, 'terrain_ids'):
return torch.full_like(target_vel_abs, default_sigma)
target_sigmas = self.terrain_max_sigmas[self.terrain_ids]
sigma = torch.full_like(target_vel_abs, default_sigma)
# based on velocity ranges, compute sigma
# v_min <= v < v_max (linear interpolation)
mask = (target_vel_abs >= v_min) & (target_vel_abs < v_max)
if mask.any():
ratio = (target_vel_abs[mask] - v_min) / (v_max - v_min)
sigma[mask] = default_sigma + ratio * (target_sigmas[mask] - default_sigma)
# v >= v_max
mask = target_vel_abs >= v_max
if mask.any():
sigma[mask] = target_sigmas[mask]
# based on terrain level, compute sigma
level_scale = torch.clamp(torch.exp((self.terrain_levels.float() + 1.0) / 10.0) - 1.0, max=1.0)
sigma = default_sigma + level_scale * (sigma - default_sigma)
return sigma
def _reward_tracking_lin_vel(self):
# Tracking of linear velocity commands (xy axes)
if self.cfg.rewards.dynamic_sigma is None:
sigma_x = sigma_y = self.cfg.rewards.tracking_sigma
else:
vmin = self.dynamic_sigma_cfg["min_lin_vel"]
vmax = self.dynamic_sigma_cfg["max_lin_vel"]
sigma_x = self._get_dynamic_sigma(torch.abs(self.commands[:, 0]), vmin, vmax)
sigma_y = self._get_dynamic_sigma(torch.abs(self.commands[:, 1]), vmin, vmax)
lin_vel_error_sq = torch.square(self.commands[:, :2] - self.base_lin_vel[:, :2])
scaled_error = lin_vel_error_sq[:, 0] / sigma_x + lin_vel_error_sq[:, 1] / sigma_y
# print(f"{self.base_lin_vel[:, :2]=}, {lin_vel_error_sq=}")
return torch.exp(-scaled_error)
def _reward_tracking_ang_vel(self):
# Tracking of angular velocity commands (yaw)
if self.cfg.rewards.dynamic_sigma is None:
sigma = self.cfg.rewards.tracking_sigma
else:
vmin = self.dynamic_sigma_cfg["min_ang_vel"]
vmax = self.dynamic_sigma_cfg["max_ang_vel"]
sigma = self._get_dynamic_sigma(torch.abs(self.commands[:, 2]), vmin, vmax)
ang_vel_error_sq = torch.square(self.commands[:, 2] - self.base_ang_vel[:, 2])
return torch.exp(-ang_vel_error_sq/sigma)
def _reward_feet_air_time(self):
# Reward long steps
# Need to filter the contacts because the contact reporting of PhysX is unreliable on meshes
contact = self.contact_forces[:, self.feet_indices, 2] > 1.
contact_filt = torch.logical_or(contact, self.last_contacts)
self.last_contacts = contact
first_contact = (self.feet_air_time > 0.) * contact_filt
self.feet_air_time += self.dt
rew_airTime = torch.sum((self.feet_air_time - 0.5) * first_contact, dim=1) # reward only on first contact with the ground
rew_airTime *= torch.norm(self.commands[:, :2], dim=1) > 0.1 #no reward for zero command
self.feet_air_time *= ~contact_filt
return rew_airTime
def _reward_stumble(self):
# Penalize feet hitting vertical surfaces
return torch.any(torch.norm(self.contact_forces[:, self.feet_indices, :2], dim=2) >\
5 *torch.abs(self.contact_forces[:, self.feet_indices, 2]), dim=1)
def _reward_stand_still(self):
# Penalize motion at zero commands
return torch.sum(torch.abs(self.dof_pos - self.default_dof_pos), dim=1) * (torch.norm(self.commands[:, :2], dim=1) < 0.1)
def _reward_feet_contact_forces(self):
# penalize high contact forces
return torch.sum((torch.norm(self.contact_forces[:, self.feet_indices, :], dim=-1) - self.cfg.rewards.max_contact_force).clip(min=0.), dim=1)
def _reward_action_smoothness(self):
# a_t - 2a_{t-1} + a_{t-2}
if not hasattr(self, 'last_last_actions'):
self.last_last_actions = torch.zeros_like(self.last_actions)
rew = torch.sum((self.actions - 2 * self.last_actions + self.last_last_actions).pow(2), dim=1)
self.last_last_actions[:] = self.last_actions[:]
return rew
def _reward_dof_power(self):
# Penalize power consumption
power = self.torques * self.dof_vel
rew = torch.sum(torch.abs(power), dim=1)
return rew
def _get_base_height(self):
if not self.cfg.terrain.measure_heights:
return self.root_states[:, 2]
# 根据高度扫描点计算base link到地面估计高度
masked_heights = self.measured_heights * self.base_height_scan_mask.unsqueeze(0)
sum_heights = masked_heights.sum(dim=1)
estimated_ground_z = sum_heights / self.num_base_height_scan_points
base_z = self.root_states[:, 2]
base_height = base_z - estimated_ground_z # (N,)
return base_height
def _reward_correct_base_height(self):
base_height = self._get_base_height()
rew = torch.square(base_height - self.cfg.rewards.base_height_target)
return rew
def _reward_feet_regulation(self):
# CTS抬腿正则奖励, 在脚末端速度增大同时, 要求高度尽可能高
base_height = self._get_base_height() # 更新刚体空间位置 (开悟比赛无法修改环境, 只能在奖励中完成计算了)
feet_pos = self.rigid_body_states.view(self.num_envs, self.num_bodies, 13)[:, self.feet_indices, 0:3]
feet_xy_vel = self.rigid_body_states.view(self.num_envs, self.num_bodies, 13)[:, self.feet_indices, 7:9]
base_pos = self.root_states[:, 0:3].unsqueeze(1)
delta_feet = feet_pos - base_pos
feet2base_height = (delta_feet * self.projected_gravity.unsqueeze(1)).sum(-1) # 脚相对于身体的高度 (N, 4)
feet_height = torch.clamp(base_height.unsqueeze(1) - feet2base_height, min=0.0) # 脚相对于地面的高度 (N, 4)
rew = (feet_xy_vel.pow(2).sum(-1) * torch.exp(-feet_height / (0.025 * self.cfg.rewards.base_height_target))).sum(-1)
return rew
def _reward_similar_to_default(self):
# Penalize joint poses far away from default pose
return torch.sum(torch.abs(self.dof_pos - self.default_dof_pos), dim=1)
def _reward_upright(self):
return (-1 - self.projected_gravity[:, 2]) / 2
def _reward_legs_distance(self):
# Penalize legs being too close to each other
# feet_names: [FL_foot, FR_foot, RL_foot, RR_foot]
feet_pos_world = self.rigid_body_states.view(self.num_envs, self.num_bodies, 13)[:, self.feet_indices, 0:3] # (N, 4, 3)
base_pos = self.root_states[:, 0:3] # (N, 3)
base_quat = self.base_quat # (N, 4)
feet_pos_relative_world = feet_pos_world - base_pos.unsqueeze(1) # (N, 4, 3)
local_pos = quat_rotate_inverse(
base_quat.repeat_interleave(4, dim=0),
feet_pos_relative_world.reshape(-1, 3)
).reshape(self.num_envs, 4, 3) # (N, 4, 3)
dy_front = local_pos[:, 0, 1] - local_pos[:, 1, 1] # (N,)
dy_rear = local_pos[:, 2, 1] - local_pos[:, 3, 1] # (N,)
min_dist = self.cfg.rewards.min_legs_distance
rew_front = torch.square(torch.clamp(min_dist - dy_front, min=0.0))
rew_rear = torch.square(torch.clamp(min_dist - dy_rear, min=0.0))
return rew_front + rew_rear