Architecture:Specification of BABEL Modules

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This page contains detailed information about a collection of modules and their role in the control architecture. The complete list of modules available for download is available here.

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Layer 1: HAD Modules

All the interfaces are defined in the previous section.

Module (ICE) name	Description	Implemented Driver Interfaces
HAD_MobileBase_Pioneer	Driver for the Pioneer3 DX/AT mobile bases, through a COM serial port and the ARIA library.	DRV_ALIASES, DRV_MOBILE_BASE, DRV_IOBOARD, DRV_BATTERY_LEVEL
HAD_MobileBase_Simulator	A simulated 2D mobile base.	DRV_ALIASES, DRV_IOBOARD, DRV_MOBILE_BASE, DRV_2D_RANGE_SCANNER
HAD_Laser_Sick_USB	Driver for the SICK laser range scanner via RS422-USB board. Hw version is JLBC/APR-05.	DRV_ALIASES, DRV_2D_RANGE_SCANNER
HAD_Laser_Hokuyo	Driver for the HOKUYO laser range scanner via a COM serial port.	DRV_ALIASES, DRV_2D_RANGE_SCANNER
HAD_GPS	Driver for COM-connected GPSs.	DRV_ALIASES, DRV_GPS
HAD_GasSensors	Driver for the custom-built e-Noses (Hardware Feb-2007).	DRV_ALIASES, DRV_GAS_SENSOR
HAD_IMU_XSens	Driver for the XSENS IMU.	DRV_ALIASES, DRV_IMU_SENSOR
HAD_Generic_Camera	Driver for any OpenCV/FFmpeg/Bumblebee camera (any camera supported by MRPT's CCameraSensor).	DRV_ALIASES, DRV_CAMERA_SENSOR

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Layer 2: Basic Sensory (BS) Modules

Recall that all these modules share a common IF as described in the previous section.

BS_IncrementalEgoMotion

• Description: This module collects data from odometry, and possibly from visual odometry, etc... to provide incremental estimations of the robot pose.

IMPORTANT NOTE: If some module is interested in a detailed list of robot pose increments, it MUST listen for events launched by this module and read all of the increments (see table of events).

• Interface:

BABEL service group	BABEL services to implement
EGO_MOTION The interface for Ego-Motion measurements.	<cpp> getAction( out COMMON::SeqOfBytes act, out boolean error ) </cpp>	Return the last action as a serialized MRPT object of the class mrpt::slam::CAction. This can be a 2D or 3D incremental movement of the robot.

BS_Vision

• Description: This module collects images from the available cameras and:
  • Provides the raw images, as CObservationImage or CObservationStereoImages objects.
  • Performs real-time feature tracking from stereo images (if available) and provides the tracked landmarks as an object of the class CObservationVisualLandmarks.

BS_RangeSensors

• Description: This module collects data from laser range scanners, and ultrasonic sensors.

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Layer 2: Basic Actuators (BA) Modules

BA_RoboticBase

• Description: This module implements DRV_MOBILE_BASE and redirects all the calls to the actual underlying device, either a real robot or the simulator.

This is the module to use when one wants the mobile base to move or stop, or one wants to read odometry.

BA_JoystickControl

• Description: This module reads command from a Joystick and send the motion commands to BA_RoboticBase. It can be enabled/disabled from the module console.

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Layer 3: Sensory Detector (SD) Modules

SD_PeopleDetector

• Description: This module detects people around the robot using sensor data from range scanners, images, etc....
• Interface: Create a new type of observation? and/or add some specific method to retrieve the detected data.

SD_Local3DMap

• Description: This module maintains a 3D representation of close obstacles around the robot, by fusing data from sonars, laser scanners, and stereo vision.
• Interface: TODO: Specific IF to retrieve:
  • A 2D obstacle point map.
  • A 2D occupancy grid.
  • A 3D point cloud.

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Layer 3: Function Executors (FE) Modules

Recall that all these modules implement the Common Actions Interface.

FE_ReactiveNavigation

Controls the reactive navigation capabilities of the robot in 2D. If a request is received while navigating, the previous one is automatically marked as cancelled.

• Action: "navigate"
• Action parameters (text lines within 'params' in the service executeAction(...) ):
  • "target_x = ...": The target location (in meters), X-coordinate in the current sub-map.
  • "target_y = ...": The target location (in meters), Y-coordinate in the current sub-map.
  • "relative = 0 | 1" (OPTIONAL, default=0): If set to "1", (x,y) coordinates are interpreted as relative to the current robot pose.
  • "max_dist = ...": (OPTIONAL) The distance (in meters) to the target location such as navigation can be considered successful.
  • "max_speed = ...": (OPTIONAL) If supplied, indicates the max. speed (m/s) of the robot. Angular max. speed is automatically derived. This can be used in situations known to be dangerous for the robot.

FE_DoorOpening

Asks a nearby human to open the door.

• Action: "openDoor"
• Action parameters (text lines within 'params' in the service executeAction(...) ):
  • None.

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Layers 2/3: Others

The following modules don't fit within either Actuators or Sensors, but they are required by other modules in layers 2,3 or in the higher-layers.

Localization_PF

• Global localization and pose tracking for a mobile robot using range sensors (lasers/sonars) and a global map.

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A practical example

An example of the low-level control architecture for a 2D robot with 2 laser scanners and a stereo camera: