Franka URDF does not import properly

[etaoxing]

Edit:

Looks like the visual meshes are just flipped, the collision bodies are correct. Would be nice to have a flip_visual_attachments: Switch Meshes from Z-up left-handed system to Y-up Right-handed coordinate system. option for wp.sim.parse_urdf(), like in isaacgym:

Screenshot (collision shapes)...

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franka_panda.urdf

Screenshot (visual meshes wrong)...

xarm6_robot.urdf

Screenshot (works as intended)...

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Code to repro...

Modified `example_quadruped.py`: ```python import math import os import numpy as np import warp as wp import warp.examples import warp.sim import warp.sim.render wp.init() # Taken from env/environment.py def compute_env_offsets(num_envs, env_offset=(5.0, 0.0, 5.0), up_axis="Y"): # compute positional offsets per environment env_offset = np.array(env_offset) nonzeros = np.nonzero(env_offset)[0] num_dim = nonzeros.shape[0] if num_dim > 0: side_length = int(np.ceil(num_envs ** (1.0 / num_dim))) env_offsets = [] else: env_offsets = np.zeros((num_envs, 3)) if num_dim == 1: for i in range(num_envs): env_offsets.append(i * env_offset) elif num_dim == 2: for i in range(num_envs): d0 = i // side_length d1 = i % side_length offset = np.zeros(3) offset[nonzeros[0]] = d0 * env_offset[nonzeros[0]] offset[nonzeros[1]] = d1 * env_offset[nonzeros[1]] env_offsets.append(offset) elif num_dim == 3: for i in range(num_envs): d0 = i // (side_length * side_length) d1 = (i // side_length) % side_length d2 = i % side_length offset = np.zeros(3) offset[0] = d0 * env_offset[0] offset[1] = d1 * env_offset[1] offset[2] = d2 * env_offset[2] env_offsets.append(offset) env_offsets = np.array(env_offsets) min_offsets = np.min(env_offsets, axis=0) correction = min_offsets + (np.max(env_offsets, axis=0) - min_offsets) / 2.0 if isinstance(up_axis, str): up_axis = "XYZ".index(up_axis.upper()) correction[up_axis] = 0.0 # ensure the envs are not shifted below the ground plane env_offsets -= correction return env_offsets class Example: def __init__(self, stage=None, num_envs=1, print_timers=True): self.num_envs = num_envs articulation_builder = wp.sim.ModelBuilder() wp.sim.parse_urdf( os.path.join( os.path.dirname(__file__), "assets/franka_description/robots/franka_panda.urdf", # "assets/xarm/xarm6_robot.urdf", ), articulation_builder, xform=wp.transform([0.0, 0.0, 0.0], wp.quat_from_axis_angle(wp.vec3(1.0, 0.0, 0.0), -math.pi * 0.5)), floating=False, density=1000, armature=0.1, stiffness=100, damping=40, # contact_ke=1.0e4, # contact_kd=1.0e2, # contact_kf=1.0e2, # contact_mu=1.0, # limit_ke=1.0e4, # limit_kd=1.0e1, ) builder = wp.sim.ModelBuilder() self.sim_time = 0.0 self.frame_dt = 1.0 / 60.0 episode_duration = 0.5 # seconds self.episode_frames = int(episode_duration / self.frame_dt) self.sim_substeps = 16 self.sim_dt = self.frame_dt / self.sim_substeps offsets = compute_env_offsets(num_envs) for i in range(num_envs): builder.add_builder(articulation_builder, xform=wp.transform(offsets[i], wp.quat_identity())) builder.joint_axis_mode = [wp.sim.JOINT_MODE_TARGET_POSITION] * len(builder.joint_axis_mode) builder.joint_q[-9:] = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] builder.joint_act[-9:] = [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] # builder.joint_q[-9:] = [0, 0.1963, 0, -2.6180, 0, 2.9416, 0.7854, 0.035, 0.035] # builder.joint_act[-9:] = [0, 0.1963, 0, -2.6180, 0, 2.9416, 0.7854, 0.035, 0.035] # builder.joint_q[-12:] = [0.2, 0.4, -0.6, -0.2, -0.4, 0.6, -0.2, 0.4, -0.6, 0.2, -0.4, 0.6] # builder.joint_act[-12:] = [0.2, 0.4, -0.6, -0.2, -0.4, 0.6, -0.2, 0.4, -0.6, 0.2, -0.4, 0.6] np.set_printoptions(suppress=True) # finalize model self.model = builder.finalize() self.model.ground = False # self.model.gravity = 0.0 # self.model.joint_attach_ke = 16000.0 # self.model.joint_attach_kd = 200.0 # self.integrator = wp.sim.XPBDIntegrator() # self.integrator = wp.sim.SemiImplicitIntegrator() self.integrator = wp.sim.FeatherstoneIntegrator(self.model) self.renderer = None if stage: self.renderer = wp.sim.render.SimRenderer(self.model, stage) self.print_timers = print_timers self.state_0 = self.model.state() self.state_1 = self.model.state() wp.sim.eval_fk(self.model, self.model.joint_q, self.model.joint_qd, None, self.state_0) self.use_graph = wp.get_device().is_cuda self.graph = None if self.use_graph: with wp.ScopedCapture() as capture: self.simulate() self.graph = capture.graph def simulate(self): for _ in range(self.sim_substeps): self.state_0.clear_forces() wp.sim.collide(self.model, self.state_0) self.integrator.simulate(self.model, self.state_0, self.state_1, self.sim_dt) self.state_0, self.state_1 = self.state_1, self.state_0 def step(self): with wp.ScopedTimer("step", active=True, print=self.print_timers): if self.use_graph: wp.capture_launch(self.graph) else: self.simulate() self.sim_time += self.frame_dt def render(self): if self.renderer is None: return with wp.ScopedTimer("render", active=True, print=self.print_timers): self.renderer.begin_frame(self.sim_time) self.renderer.render(self.state_0) self.renderer.end_frame() if __name__ == "__main__": stage_path = "example_franka.usd" example = Example(stage_path, num_envs=1) for _ in range(example.episode_frames): example.step() example.render() if example.renderer: example.renderer.save() ```

[etaoxing]

Would also be nice if wp.sim.parse_urdf() automatically resolved filename="package://... paths!

Currently editing URDFs by hand:

<mesh filename="package://franka_description/meshes/collision/link0.obj"/>

->

<mesh filename="../meshes/collision/link0.obj"/>

[etaoxing]

Would also be nice to have a flag that loads torque ("effort) and velocity ("velocity") limits per joint from the URDF:

<joint>
  <limit lower="0", upper="0", effort="0", velocity="0">
</joint>

[eric-heiden]

Hi @etaoxing,

Thank you for reporting these issues! We will have the URDF importer fixed in the next release. The visual meshes in the COLLADA format actually have the up_axis encoded, so by replacing this line with

m = trimesh.load(filename, force="mesh")

we can force trimesh to bake the transforms into the mesh when importing it.

We will also add support for the package:// handling in the next version.

Support for torque and velocity limits is on our ToDo list but will take a bit longer to implement for the different integrators.