MobileRobot/mobile_robot_basic_en.ipynb

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    "**Table of contents**<a id='toc0_'></a>    \n",
    "- [Mobile Robot](#toc1_)    \n",
    "- [Starting pybullet](#toc2_)    \n",
    "- [Initial Setup of pybullet](#toc3_)    \n",
    "- [Creating the Mobile Robot](#toc4_)    \n",
    "- [Running the Simulation](#toc5_)    \n",
    "\n",
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    "# <a id='toc1_'></a>[Mobile Robot](#toc0_)\n",
    "\n",
    "This notebook explains the steps to create and operate a two-wheeled mobile robot.\n",
    "\n",
    "(For a manual summarizing the functions available in pybullet, please refer to [this link](https://github.com/bulletphysics/bullet3/blob/master/docs/pybullet_quickstartguide.pdf).)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# <a id='toc2_'></a>[Starting pybullet](#toc0_)"
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     "text": [
      "pybullet build time: Nov 28 2023 23:45:17\n"
     ]
    },
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     "name": "stdout",
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     "text": [
      "startThreads creating 1 threads.\n",
      "starting thread 0\n",
      "started thread 0 \n",
      "argc=2\n",
      "argv[0] = --unused\n",
      "argv[1] = --start_demo_name=Physics Server\n",
      "ExampleBrowserThreadFunc started\n",
      "X11 functions dynamically loaded using dlopen/dlsym OK!\n",
      "X11 functions dynamically loaded using dlopen/dlsym OK!\n",
      "Creating context\n",
      "Created GL 3.3 context\n",
      "Direct GLX rendering context obtained\n",
      "Making context current\n",
      "GL_VENDOR=Mesa\n",
      "GL_RENDERER=llvmpipe (LLVM 15.0.7, 256 bits)\n",
      "GL_VERSION=4.5 (Core Profile) Mesa 23.2.1-1ubuntu3.1~22.04.2\n",
      "GL_SHADING_LANGUAGE_VERSION=4.50\n",
      "pthread_getconcurrency()=0\n",
      "Version = 4.5 (Core Profile) Mesa 23.2.1-1ubuntu3.1~22.04.2\n",
      "Vendor = Mesa\n",
      "Renderer = llvmpipe (LLVM 15.0.7, 256 bits)\n",
      "b3Printf: Selected demo: Physics Server\n",
      "startThreads creating 1 threads.\n",
      "starting thread 0\n",
      "started thread 0 \n",
      "MotionThreadFunc thread started\n"
     ]
    }
   ],
   "source": [
    "import pybullet\n",
    "import pybullet_data\n",
    "physics_client = pybullet.connect(pybullet.GUI) "
   ]
  },
  {
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   "metadata": {},
   "source": [
    "# <a id='toc3_'></a>[Initial Setup of pybullet](#toc0_)"
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      "ven = Mesa\n",
      "ven = Mesa\n"
     ]
    }
   ],
   "source": [
    "pybullet.resetSimulation() # Reset the simulation space\n",
    "pybullet.setAdditionalSearchPath(pybullet_data.getDataPath()) # Add path to necessary data for pybullet\n",
    "pybullet.setGravity(0.0, 0.0, -9.8) # Set gravity as on Earth\n",
    "time_step = 1./240.\n",
    "pybullet.setTimeStep(time_step) # Set the elapsed time per step\n",
    "\n",
    "# Load the floor\n",
    "plane_id = pybullet.loadURDF(\"plane.urdf\")\n",
    "\n",
    "# Set the camera position and other parameters in GUI mode\n",
    "camera_distance = 2.0\n",
    "camera_yaw = 0.0 # deg\n",
    "camera_pitch = -20 # deg\n",
    "camera_target_position = [0.0, 0.0, 0.0]\n",
    "pybullet.resetDebugVisualizerCamera(camera_distance, camera_yaw, camera_pitch, camera_target_position)"
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   "source": [
    "# <a id='toc4_'></a>[Creating the Mobile Robot](#toc0_)\n",
    "This time, we will create a two-wheeled robot `simple_two_wheel_car.urdf`.  \n",
    "The structure of this robot is as shown in the figure below (sensors are explained in `mobile_robot_sensor.ipynb`).\n",
    "\n",
    "![](../images/MobileRobot/mobile_robot1.png)\n",
    "\n",
    "![](../images/MobileRobot/mobile_robot2.png)"
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   "source": [
    "# Load the robot\n",
    "car_start_pos = [0, 0, 0.1]  # Set the initial position (x, y, z)\n",
    "car_start_orientation = pybullet.getQuaternionFromEuler([0, 0, 0])  # Set the initial orientation (roll, pitch, yaw)\n",
    "# It seems that the mesh in the urdf file does not reflect textures, so each link is colored with rgba tags\n",
    "car_id = pybullet.loadURDF(\"../urdf/simple_two_wheel_car.urdf\", car_start_pos, car_start_orientation)"
   ]
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   "source": [
    "# <a id='toc5_'></a>[Running the Simulation](#toc0_)\n",
    "With `setJointMotorControl2`, you can operate the specified joints of the specified robot.  \n",
    "Here, to operate with a velocity command, `VELOCITY_CONTROL` is specified as the third argument.\n"
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    "import time\n",
    "RIGHT_WHEEL_JOINT_IDX = 0\n",
    "LEFT_WHEEL_JOINT_IDX = 1\n",
    "for i in range(500):\n",
    "    # Move forward at speed 10\n",
    "    pybullet.setJointMotorControl2(car_id, LEFT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=10)\n",
    "    pybullet.setJointMotorControl2(car_id, RIGHT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=10)\n",
    "\n",
    "    # Move backward at speed 5\n",
    "    # pybullet.setJointMotorControl2(car_id, LEFT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=-5)\n",
    "    # pybullet.setJointMotorControl2(car_id, RIGHT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=-5)\n",
    "\n",
    "    # Turn right\n",
    "    # pybullet.setJointMotorControl2(car_id, LEFT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=10)\n",
    "    # pybullet.setJointMotorControl2(car_id, RIGHT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=2)\n",
    "\n",
    "    # Turn left\n",
    "    # pybullet.setJointMotorControl2(car_id, LEFT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=2)\n",
    "    # pybullet.setJointMotorControl2(car_id, RIGHT_WHEEL_JOINT_IDX, pybullet.VELOCITY_CONTROL, targetVelocity=10)\n",
    "\n",
    "    pybullet.stepSimulation()\n",
    "    time.sleep(time_step)"
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