{
"cells": [
{
"cell_type": "markdown",
"id": "f96fd41d",
"metadata": {},
"source": [
"# Importing a robot arm multibody model from a URDF file\n",
"The purpose of this notebook is to\n",
"- demonstrate the creation of a {py:class}`Karana.Dynamics.Multibody` instance for a robot arm from a URDF model file \n",
"- show the structure of the loaded model\n",
"- show a 3D visualization of the robot arm\n",
"- serve as a `hello world` script for verifying a proper `kdFlex` installation\n",
"\n",
"Resources\n",
"- [Other notebook examples](https://portal.karanadyn.com/docs/examples_page.html) \n",
"- [kdFlex Documentation](https://portal.karanadyn.com/docs/index.html)\n",
"\n",
"**Acknowledgements**\n",
"The Barrett WAM urdf is sourced from the public repository [barrett-ros2-pkg](https://git.barrett.com/software/barrett-ros2-pkg.git). Thank you to the authors and contributors."
]
},
{
"cell_type": "markdown",
"id": "5978859c",
"metadata": {},
"source": [
"Import **kdFlex** Python modules objects for use later"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "dce602b8",
"metadata": {},
"outputs": [],
"source": [
"from pathlib import Path\n",
"import atexit\n",
"\n",
"import Karana.KUtils.BasicPrefab as kub\n",
"from Karana.KUtils.Sim import Sim"
]
},
{
"cell_type": "markdown",
"id": "bcb35c5b",
"metadata": {},
"source": [
"Build the filepath to the URDF file we will import"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "fd13f1bc",
"metadata": {},
"outputs": [],
"source": [
"resources = Path().absolute().parent / \"resources\"\n",
"urdf_file = resources / \"wam7dof\" / \"wam7dof_hand.urdf\""
]
},
{
"cell_type": "markdown",
"id": "c8b05075",
"metadata": {},
"source": [
"Import the URDF file to create a BasicPrefabDS. The \"DS\" is short for \"Data Structure\". This is kdFlex's native, file-format agnostic way of specifying a multibody and associated KModels. We'll use this next to create our simulation."
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "c6ce1a4a",
"metadata": {},
"outputs": [],
"source": [
"basic_prefab_ds = kub.BasicPrefabDS.fromFile(urdf_file)"
]
},
{
"cell_type": "markdown",
"id": "4fd06632",
"metadata": {},
"source": [
"Instantiate and configure the {py:class}`Karana.Dynamics.Multibody` based on the BasicPrefabDS description."
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "8e99d2b9",
"metadata": {},
"outputs": [],
"source": [
"sim, prefab = Sim.fromBasicPrefabDS(basic_prefab_ds)"
]
},
{
"cell_type": "markdown",
"id": "3c4aeea4",
"metadata": {},
"source": [
"Finalize the model to get it ready for use."
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "115f56a0",
"metadata": {},
"outputs": [],
"source": [
"sim.mb.ensureHealthy()\n",
"sim.mb.resetData()"
]
},
{
"cell_type": "markdown",
"id": "97db71f8",
"metadata": {},
"source": [
"Set up the 3D graphics."
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "024e4376",
"metadata": {},
"outputs": [
{
"data": {
"text/html": [
"\n",
" \n",
" \n",
"
\n",
" "
],
"text/plain": [
""
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"_, graphics = sim.setupGraphics(port=0)\n",
"graphics.defaultCamera().pointCameraAt(\n",
" offset=[0.2, 0.5, 1.7],\n",
" target=[0, 0, 1],\n",
" up=[1, 0, 0],\n",
")\n",
"del graphics"
]
},
{
"cell_type": "markdown",
"id": "2b90d05e",
"metadata": {},
"source": [
"Display the bodies in the multibody model."
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "e9ab8bad",
"metadata": {},
"outputs": [],
"source": [
"sim.mb.displayModel()"
]
},
{
"cell_type": "markdown",
"id": "77a82391",
"metadata": {},
"source": [
"Display the topological structure of the multibody system"
]
},
{
"cell_type": "code",
"execution_count": 8,
"id": "e88214b0",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"[WebUI] Web server is running on port 33661\n",
"You may be able to connect in your browser at:\n",
"\t\u001b[1mhttp://newton:33661\u001b[0m\n",
"\n",
" ===== Bodies for 'wam7dof' Multibody =====\n",
"Legend:\n",
" No. topological body number\n",
" Hinge hinge type followed by one prescribed optional marker per subhinge\n",
" P prescribed subhinge; blank means unprescribed\n",
" DOFs hinge-local / DOFs accumulated before this body\n",
"========================================================\n",
"No. Body Parent Hinge DOFs\n",
"------ ------------ ---------------- ---------- ----\n",
"1. FirstLink wam7dof_MBVROOT_ REVOLUTE 1/0\n",
"2. SecondLink FirstLink REVOLUTE 1/1\n",
"3. ThirdLink SecondLink REVOLUTE 1/2\n",
"4. FourthLink ThirdLink REVOLUTE 1/3\n",
"5. FifthLink FourthLink REVOLUTE 1/4\n",
"6. SixthLink FifthLink REVOLUTE 1/5\n",
"7. SeventhLink SixthLink REVOLUTE 1/6\n",
"8. bhand_base SeventhLink LOCKED 0/7\n",
"9. bhand_link11 bhand_base REVOLUTE 1/7\n",
"10. bhand_link12 bhand_link11 REVOLUTE 1/8\n",
"11. bhand_link13 bhand_link12 REVOLUTE 1/9\n",
"12. bhand_link21 bhand_base REVOLUTE 1/10\n",
"13. bhand_link22 bhand_link21 REVOLUTE 1/11\n",
"14. bhand_link23 bhand_link22 REVOLUTE 1/12\n",
"15. bhand_link32 bhand_base REVOLUTE 1/13\n",
"16. bhand_link33 bhand_link32 REVOLUTE 1/14\n",
"--------------------------------------------------------\n",
"Totals 15\n",
"LEGEND: [ ] [/num embedded bodies > 0] 0>\n",
"|-wam7dof_MBVROOT_\n",
" |-[REVOLUTE] FirstLink\n",
" |-[REVOLUTE] SecondLink\n",
" |-[REVOLUTE] ThirdLink\n",
" |-[REVOLUTE] FourthLink\n",
" |-[REVOLUTE] FifthLink\n",
" |-[REVOLUTE] SixthLink\n",
" |-[REVOLUTE] SeventhLink\n",
" |-[LOCKED] bhand_base\n",
" |-[REVOLUTE] bhand_link11\n",
" |-[REVOLUTE] bhand_link12\n",
" |-[REVOLUTE] bhand_link13\n",
" |-[REVOLUTE] bhand_link21\n",
" |-[REVOLUTE] bhand_link22\n",
" |-[REVOLUTE] bhand_link23\n",
" |-[REVOLUTE] bhand_link32\n",
" |-[REVOLUTE] bhand_link33\n",
"\n"
]
}
],
"source": [
"sim.mb.dumpTree()"
]
},
{
"cell_type": "markdown",
"id": "df73d006",
"metadata": {},
"source": [
"Animate the graphics by articulating the individual joints."
]
},
{
"cell_type": "code",
"execution_count": 9,
"id": "8f575fb9",
"metadata": {},
"outputs": [],
"source": [
"sim.mb.articulateBodies()"
]
},
{
"cell_type": "markdown",
"id": "0ec19236",
"metadata": {},
"source": [
"Cleanup"
]
},
{
"cell_type": "code",
"execution_count": 10,
"id": "136c1c30",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
""
]
},
"execution_count": 10,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"def cleanup():\n",
" \"\"\"Cleanup the simulation.\"\"\"\n",
" global basic_prefab_ds, prefab, sim\n",
" del basic_prefab_ds, prefab, sim\n",
"\n",
"\n",
"atexit.register(cleanup)"
]
}
],
"metadata": {
"docs": {
"recording": "https://portal.karanadyn.com/tutorial_videos/example_urdf.mp4",
"tags": [
"dynamics",
"urdf",
"import",
"robot",
"WAM"
]
},
"kernelspec": {
"display_name": "Python 3 (ipykernel)",
"language": "python",
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.12.3"
},
"name": "notebook.ipynb"
},
"nbformat": 4,
"nbformat_minor": 5
}