python/examples/franka_attractor.py

"""
Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.

NVIDIA CORPORATION and its licensors retain all intellectual property
and proprietary rights in and to this software, related documentation
and any modifications thereto. Any use, reproduction, disclosure or
distribution of this software and related documentation without an express
license agreement from NVIDIA CORPORATION is strictly prohibited.


Franka Attractor
----------------
Positional control of franka panda robot with a target attractor that the robot tries to reach
"""

import math
from isaacgym import gymapi
from isaacgym import gymutil

# Initialize gym
gym = gymapi.acquire_gym()

# Parse arguments
args = gymutil.parse_arguments(description="Franka Attractor Example")

# configure sim
sim_params = gymapi.SimParams()
sim_params.dt = 1.0 / 60.0
sim_params.substeps = 2
if args.physics_engine == gymapi.SIM_FLEX:
    sim_params.flex.solver_type = 5
    sim_params.flex.num_outer_iterations = 4
    sim_params.flex.num_inner_iterations = 15
    sim_params.flex.relaxation = 0.75
    sim_params.flex.warm_start = 0.8
elif args.physics_engine == gymapi.SIM_PHYSX:
    sim_params.physx.solver_type = 1
    sim_params.physx.num_position_iterations = 4
    sim_params.physx.num_velocity_iterations = 1
    sim_params.physx.num_threads = args.num_threads
    sim_params.physx.use_gpu = args.use_gpu

sim_params.use_gpu_pipeline = False
if args.use_gpu_pipeline:
    print("WARNING: Forcing CPU pipeline.")

sim = gym.create_sim(args.compute_device_id, args.graphics_device_id, args.physics_engine, sim_params)

if sim is None:
    print("*** Failed to create sim")
    quit()

# Create viewer
viewer = gym.create_viewer(sim, gymapi.CameraProperties())
if viewer is None:
    print("*** Failed to create viewer")
    quit()

# Add ground plane
plane_params = gymapi.PlaneParams()
gym.add_ground(sim, plane_params)

# Load franka asset
asset_root = "../../assets"
franka_asset_file = "urdf/franka_description/robots/franka_panda.urdf"

asset_options = gymapi.AssetOptions()
asset_options.fix_base_link = True
asset_options.flip_visual_attachments = True
asset_options.armature = 0.01

print("Loading asset '%s' from '%s'" % (franka_asset_file, asset_root))
franka_asset = gym.load_asset(
    sim, asset_root, franka_asset_file, asset_options)

# Set up the env grid
num_envs = 36
spacing = 1.0
env_lower = gymapi.Vec3(-spacing, 0.0, -spacing)
env_upper = gymapi.Vec3(spacing, spacing, spacing)

# Some common handles for later use
envs = []
franka_handles = []
franka_hand = "panda_hand"

# Attractor setup
attractor_handles = []
attractor_properties = gymapi.AttractorProperties()
attractor_properties.stiffness = 5e5
attractor_properties.damping = 5e3

# Make attractor in all axes
attractor_properties.axes = gymapi.AXIS_ALL
pose = gymapi.Transform()
pose.p = gymapi.Vec3(0, 0.0, 0.0)
pose.r = gymapi.Quat(-0.707107, 0.0, 0.0, 0.707107)

# Create helper geometry used for visualization
# Create an wireframe axis
axes_geom = gymutil.AxesGeometry(0.1)
# Create an wireframe sphere
sphere_rot = gymapi.Quat.from_euler_zyx(0.5 * math.pi, 0, 0)
sphere_pose = gymapi.Transform(r=sphere_rot)
sphere_geom = gymutil.WireframeSphereGeometry(0.03, 12, 12, sphere_pose, color=(1, 0, 0))

print("Creating %d environments" % num_envs)
num_per_row = int(math.sqrt(num_envs))

for i in range(num_envs):
    # create env
    env = gym.create_env(sim, env_lower, env_upper, num_per_row)
    envs.append(env)

    # add franka
    franka_handle = gym.create_actor(env, franka_asset, pose, "franka", i, 2)
    body_dict = gym.get_actor_rigid_body_dict(env, franka_handle)
    props = gym.get_actor_rigid_body_states(env, franka_handle, gymapi.STATE_POS)
    hand_handle = body = gym.find_actor_rigid_body_handle(env, franka_handle, franka_hand)

    # Initialize the attractor
    attractor_properties.target = props['pose'][:][body_dict[franka_hand]]
    attractor_properties.target.p.y -= 0.1
    attractor_properties.target.p.z = 0.1
    attractor_properties.rigid_handle = hand_handle

    # Draw axes and sphere at attractor location
    gymutil.draw_lines(axes_geom, gym, viewer, env, attractor_properties.target)
    gymutil.draw_lines(sphere_geom, gym, viewer, env, attractor_properties.target)

    franka_handles.append(franka_handle)
    attractor_handle = gym.create_rigid_body_attractor(env, attractor_properties)
    attractor_handles.append(attractor_handle)

# get joint limits and ranges for Franka
franka_dof_props = gym.get_actor_dof_properties(envs[0], franka_handles[0])
franka_lower_limits = franka_dof_props['lower']
franka_upper_limits = franka_dof_props['upper']
franka_ranges = franka_upper_limits - franka_lower_limits
franka_mids = 0.5 * (franka_upper_limits + franka_lower_limits)
franka_num_dofs = len(franka_dof_props)

# override default stiffness and damping values
franka_dof_props['stiffness'].fill(1000.0)
franka_dof_props['damping'].fill(1000.0)

# Give a desired pose for first 2 robot joints to improve stability
franka_dof_props["driveMode"][0:2] = gymapi.DOF_MODE_POS

franka_dof_props["driveMode"][7:] = gymapi.DOF_MODE_POS
franka_dof_props['stiffness'][7:] = 1e10
franka_dof_props['damping'][7:] = 1.0

for i in range(num_envs):
    gym.set_actor_dof_properties(envs[i], franka_handles[i], franka_dof_props)


def update_franka(t):
    gym.clear_lines(viewer)
    for i in range(num_envs):
        # Update attractor target from current franka state
        attractor_properties = gym.get_attractor_properties(envs[i], attractor_handles[i])
        pose = attractor_properties.target
        pose.p.x = 0.2 * math.sin(1.5 * t - math.pi * float(i) / num_envs)
        pose.p.y = 0.7 + 0.1 * math.cos(2.5 * t - math.pi * float(i) / num_envs)
        pose.p.z = 0.2 * math.cos(1.5 * t - math.pi * float(i) / num_envs)

        gym.set_attractor_target(envs[i], attractor_handles[i], pose)

        # Draw axes and sphere at attractor location
        gymutil.draw_lines(axes_geom, gym, viewer, envs[i], pose)
        gymutil.draw_lines(sphere_geom, gym, viewer, envs[i], pose)


for i in range(num_envs):
    # Set updated stiffness and damping properties
    gym.set_actor_dof_properties(envs[i], franka_handles[i], franka_dof_props)

    # Set ranka pose so that each joint is in the middle of its actuation range
    franka_dof_states = gym.get_actor_dof_states(envs[i], franka_handles[i], gymapi.STATE_NONE)
    for j in range(franka_num_dofs):
        franka_dof_states['pos'][j] = franka_mids[j]
    gym.set_actor_dof_states(envs[i], franka_handles[i], franka_dof_states, gymapi.STATE_POS)

# Point camera at environments
cam_pos = gymapi.Vec3(-4.0, 4.0, -1.0)
cam_target = gymapi.Vec3(0.0, 2.0, 1.0)
gym.viewer_camera_look_at(viewer, None, cam_pos, cam_target)

# Time to wait in seconds before moving robot
next_franka_update_time = 1.5

while not gym.query_viewer_has_closed(viewer):
    # Every 0.01 seconds the pose of the attactor is updated
    t = gym.get_sim_time(sim)
    if t >= next_franka_update_time:
        update_franka(t)
        next_franka_update_time += 0.01

    # Step the physics
    gym.simulate(sim)
    gym.fetch_results(sim, True)

    # Step rendering
    gym.step_graphics(sim)
    gym.draw_viewer(viewer, sim, False)
    gym.sync_frame_time(sim)

print("Done")

gym.destroy_viewer(viewer)
gym.destroy_sim(sim)