Urdf pybullet

kscale/store/__init__.py

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+__version__ = "0.0.1"

kscale/store/bullet/MANIFEST.in

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+include . *.obj *.urdf

kscale/store/bullet/plane.obj

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+# Blender v2.66 (sub 1) OBJ File: ''
+# www.blender.org
+mtllib plane.mtl
+o Plane
+v 15.000000 -15.000000 0.000000
+v 15.000000 15.000000 0.000000
+v -15.000000 15.000000 0.000000
+v -15.000000  -15.000000 0.000000
+
+vt 15.000000 0.000000
+vt 15.000000 15.000000
+vt 0.000000 15.000000
+vt 0.000000 0.000000
+
+usemtl Material
+s off
+f 1/1 2/2 3/3
+f 1/1 3/3 4/4

kscale/store/bullet/plane.urdf

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+<?xml version="0.0" ?>
+<robot name="plane">
+    <link name="planeLink">
+        <contact>
+            <lateral_friction value="1"/>
+        </contact>
+        <inertial>
+            <origin rpy="0 0 0" xyz="0 0 0"/>
+            <mass value=".0"/>
+            <inertia ixx="0" ixy="0" ixz="0" iyy="0" iyz="0" izz="0"/>
+        </inertial>
+        <visual>
+            <origin rpy="0 0 0" xyz="0 0 0"/>
+            <geometry>
+                <mesh filename="plane.obj" scale="1 1 1"/>
+            </geometry>
+            <material name="white">
+                <color rgba="1 1 1 1"/>
+            </material>
+        </visual>
+        <collision>
+            <origin rpy="0 0 0" xyz="0 0 -5"/>
+            <geometry>
+                <box size="30 30 10"/>
+            </geometry>
+        </collision>
+    </link>
+</robot>

kscale/store/cli.py

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+"""Defines the top-level KOL CLI."""
+
+import argparse
+from typing import Sequence
+
+from kscale.store import pybullet, urdf
+
+
+def main(args: Sequence[str] | None = None) -> None:
+    parser = argparse.ArgumentParser(description="K-Scale OnShape Library", add_help=False)
+    parser.add_argument(
+        "subcommand",
+        choices=[
+            "urdf",
+            "pybullet",
+        ],
+        help="The subcommand to run",
+    )
+    parsed_args, remaining_args = parser.parse_known_args(args)
+
+    match parsed_args.subcommand:
+        case "urdf":
+            urdf.main(remaining_args)
+        case "pybullet":
+            pybullet.main(remaining_args)
+
+
+if __name__ == "__main__":
+    # python3 -m kscale.store.cli
+    main()

kscale/store/pybullet.py

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+"""Simple script to interact with a URDF in PyBullet."""
+
+import argparse
+import itertools
+import logging
+import math
+import time
+from pathlib import Path
+from typing import Sequence
+
+logger = logging.getLogger(__name__)
+
+
+def main(args: Sequence[str] | None = None) -> None:
+
+    parser = argparse.ArgumentParser(description="Show a URDF in PyBullet")
+    parser.add_argument("urdf", nargs="?", help="Path to the URDF file")
+    parser.add_argument("--dt", type=float, default=0.01, help="Time step")
+    parser.add_argument("-n", "--hide-gui", action="store_true", help="Hide the GUI")
+    parser.add_argument("--no-merge", action="store_true", help="Do not merge fixed links")
+    parser.add_argument("--hide-origin", action="store_true", help="Do not show the origin")
+    parser.add_argument("--show-inertia", action="store_true", help="Visualizes the inertia frames")
+    parser.add_argument("--see-thru", action="store_true", help="Use see-through mode")
+    parser.add_argument("--show-collision", action="store_true", help="Show collision meshes")
+    parsed_args = parser.parse_args(args)
+
+    try:
+        import pybullet as p
+    except ImportError:
+        raise ImportError("pybullet is required to run this script")
+
+    # Connect to PyBullet.
+    p.connect(p.GUI)
+    p.setGravity(0, 0, -9.81)
+    p.setRealTimeSimulation(0)
+
+    # Turn off panels.
+    if parsed_args.hide_gui:
+        p.configureDebugVisualizer(p.COV_ENABLE_GUI, 0)
+    p.configureDebugVisualizer(p.COV_ENABLE_SEGMENTATION_MARK_PREVIEW, 0)
+    p.configureDebugVisualizer(p.COV_ENABLE_DEPTH_BUFFER_PREVIEW, 0)
+    p.configureDebugVisualizer(p.COV_ENABLE_RGB_BUFFER_PREVIEW, 0)
+
+    # Enable mouse picking.
+    p.configureDebugVisualizer(p.COV_ENABLE_MOUSE_PICKING, 1)
+
+    # Loads the floor plane.
+    floor = p.loadURDF(str((Path(__file__).parent / "bullet" / "plane.urdf").resolve()))
+
+    urdf_path = Path("robot" if parsed_args.urdf is None else parsed_args.urdf)
+    if urdf_path.is_dir():
+        try:
+            urdf_path = next(urdf_path.glob("*.urdf"))
+        except StopIteration:
+            raise FileNotFoundError(f"No URDF files found in {urdf_path}")
+
+    # Load the robot URDF.
+    start_position = [0.0, 0.0, 1.0]
+    start_orientation = p.getQuaternionFromEuler([0.0, 0.0, 0.0])
+    flags = p.URDF_USE_INERTIA_FROM_FILE
+    if not parsed_args.no_merge:
+        flags |= p.URDF_MERGE_FIXED_LINKS
+    robot = p.loadURDF(str(urdf_path), start_position, start_orientation, flags=flags, useFixedBase=0)
+
+    # Display collision meshes as separate object.
+    if parsed_args.show_collision:
+        collision_flags = p.URDF_USE_INERTIA_FROM_FILE | p.URDF_USE_SELF_COLLISION_EXCLUDE_ALL_PARENTS
+        collision = p.loadURDF(str(urdf_path), start_position, start_orientation, flags=collision_flags, useFixedBase=0)
+
+        # Make collision shapes semi-transparent.
+        joint_ids = [i for i in range(p.getNumJoints(collision))] + [-1]
+        for i in joint_ids:
+            p.changeVisualShape(collision, i, rgbaColor=[1, 0, 0, 0.5])
+
+    # Initializes physics parameters.
+    p.changeDynamics(floor, -1, lateralFriction=1, spinningFriction=-1, rollingFriction=-1)
+    p.setPhysicsEngineParameter(fixedTimeStep=parsed_args.dt, maxNumCmdPer1ms=1000)
+
+    # Shows the origin of the robot.
+    if not parsed_args.hide_origin:
+        p.addUserDebugLine([0, 0, 0], [0.1, 0, 0], [1, 0, 0], parentObjectUniqueId=robot, parentLinkIndex=-1)
+        p.addUserDebugLine([0, 0, 0], [0, 0.1, 0], [0, 1, 0], parentObjectUniqueId=robot, parentLinkIndex=-1)
+        p.addUserDebugLine([0, 0, 0], [0, 0, 0.1], [0, 0, 1], parentObjectUniqueId=robot, parentLinkIndex=-1)
+
+    # Make the robot see-through.
+    joint_ids = [i for i in range(p.getNumJoints(robot))] + [-1]
+    if parsed_args.see_thru:
+        for i in joint_ids:
+            p.changeVisualShape(robot, i, rgbaColor=[1, 1, 1, 0.5])
+
+    def draw_box(pt: list[list[float]], color: tuple[float, float, float], obj_id: int, link_id: int) -> None:
+        assert len(pt) == 8
+        assert all(len(p) == 3 for p in pt)
+
+        mapping = [1, 3, 0, 2]
+        for i in range(4):
+            p.addUserDebugLine(pt[i], pt[i + 4], color, 1, parentObjectUniqueId=obj_id, parentLinkIndex=link_id)
+            p.addUserDebugLine(pt[i], pt[mapping[i]], color, 1, parentObjectUniqueId=obj_id, parentLinkIndex=link_id)
+            p.addUserDebugLine(pt[i + 4], pt[mapping[i] + 4], color, 1, parentObjectUniqueId=obj_id, parentLinkIndex=link_id)
+
+    # Shows bounding boxes around each part of the robot representing the inertia frame.
+    if parsed_args.show_inertia:
+        for i in joint_ids:
+            dynamics_info = p.getDynamicsInfo(robot, i)
+            mass = dynamics_info[0]
+            if mass <= 0:
+                continue
+            inertia = dynamics_info[2]
+            ixx = inertia[0]
+            iyy = inertia[1]
+            izz = inertia[2]
+            box_scale_x = 0.5 * math.sqrt(6 * (izz + iyy - ixx) / mass)
+            box_scale_y = 0.5 * math.sqrt(6 * (izz + ixx - iyy) / mass)
+            box_scale_z = 0.5 * math.sqrt(6 * (ixx + iyy - izz) / mass)
+
+            half_extents = [box_scale_x, box_scale_y, box_scale_z]
+            pt = [[x, y, z] for x, y, z in itertools.product(
+                [-half_extents[0], half_extents[0]],
+                [-half_extents[1], half_extents[1]],
+                [-half_extents[2], half_extents[2]]
+            )]
+            draw_box(pt, (1, 0, 0), robot, i)
+
+    # Show joint controller.
+    joints: dict[str, int] = {}
+    controls: dict[str, float] = {}
+    for i in range(p.getNumJoints(robot)):
+        joint_info = p.getJointInfo(robot, i)
+        name = joint_info[1].decode("utf-8")
+        joint_type = joint_info[2]
+        joints[name] = i
+        if joint_type == p.JOINT_PRISMATIC:
+            joint_min, joint_max = joint_info[8:10]
+            controls[name] = p.addUserDebugParameter(name, joint_min, joint_max, 0.0)
+        elif joint_type == p.JOINT_REVOLUTE:
+            joint_min, joint_max = joint_info[8:10]
+            controls[name] = p.addUserDebugParameter(name, joint_min, joint_max, 0.0)
+
+    # Run the simulation until the user closes the window.
+    last_time = time.time()
+    prev_control_values = {k: 0.0 for k in controls}
+    while p.isConnected():
+        # Reset the simulation if "r" was pressed.
+        keys = p.getKeyboardEvents()
+        if ord("r") in keys and keys[ord("r")] & p.KEY_WAS_TRIGGERED:
+            p.resetBasePositionAndOrientation(robot, start_position, start_orientation)
+            p.setJointMotorControlArray(
+                robot,
+                range(p.getNumJoints(robot)),
+                p.POSITION_CONTROL,
+                targetPositions=[0] * p.getNumJoints(robot),
+            )
+
+        # Set joint positions.
+        for k, v in controls.items():
+            try:
+                target_position = p.readUserDebugParameter(v)
+                if target_position != prev_control_values[k]:
+                    prev_control_values[k] = target_position
+                    p.setJointMotorControl2(robot, joints[k], p.POSITION_CONTROL, target_position)
+            except p.error:
+                logger.debug("Failed to set joint %s", k)
+                pass
+
+        # Step simulation.
+        p.stepSimulation()
+        cur_time = time.time()
+        time.sleep(max(0, parsed_args.dt - (cur_time - last_time)))
+        last_time = cur_time
+
+
+if __name__ == "__main__":
+    # python -m kscale.store.pybullet
+    main()