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BeeSoft User's Guide and Reference

Previous Item Next Item Chapter 16: BeeSoft™ Glossary

acceleration: The rate of change in velocity, or the change in velocity divided by the time it takes for change to occur.

angular reflection: sonar. The angle at which the sonar beam bouncing off an obstacle is directed back at that sonar. This angle depends on the texture and other characteristics of the obstacle’s surface, and its position relative to the sonar.

API: Application program Interface.

arm: Term sometimes used colloquially to refer to the B21 Manipulator.

autonomous mode: Mode of guarded-motion robotic travel in which the robot plans its route as it goes along, constructing occupancy maps of what it finds in its environment, and referring to those maps in planning its further moves.

B14 robot: Real World Interface, Inc’s small size cylindrical, mobile robot, equipped for sensing and navigation in real-world environments.

B21 robot: Real World Interface, Inc’s large size cylindrical, mobile robot, equipped for sensing and navigation in real-world environments.

base: The lower portion (about 1/4 the total height of the robot) of a B14 or B21, encompassing the wheels, motors, batteries and tactile sensors.

base control panel: On a B14, the base control panel is behind the door with the yellow dot on top, on the robot’s base. On a B21, the base control panel is set into the door with the yellow dot on top, on the robot’s base. The B21's base control panel includes the kill reset button, the system reset button and the base power switch. The B14's base control panel includes the system reset button and the base power switch

base power switch: On the B21 robot, a three-position toggle switch in the base control panel. The top position turns robot power on; the bottom position turns robot power off; the middle position is slaved to the enclosure. That is, when the base power switch is left in the middle position, you can control robot power from the top, or console, of the robot. On the B14 robot, the parallel is momentary "on/reset" and momentary "off."

baseServer:The program that gives the robot programmer a transparent interface to the robots motion controls (translation and rotation), and its sensors (sonar sensors, infrared sensors and tactile sensors).

BeeSoft™: Real World Interface, Inc.’s robot application interface software package for mobile autonomous robots.

BeeSoft Commander™: A program that presents a graphical interface enabling teleoperation of the robot, and mapping functions.

BeeSoft Mapper™: An example application based on BeeSoft.

BeeSoft Planner™: An example application based on BeeSoft. The BeeSoft Plannerlets your robot plan the optimal route through its environment.

bump panel: Another name for smart panel™; the panels enclosing the robot. The B14 has 4 on the upper enclosure and 6 around its base; the B21 has 6 on the upper enclosure and 8 around its base.) Behind each of these panels, or doors, are mounted, at the corners, bump switches, or tactile sensors, which notify the robot when bumped or pushed.

bump switch: Pressure-sensitive switches, mounted behind the corners of each bump panel (or smart panel™) around the robot. There are 24 on the upper enclosure and 32 on the base of a B21; there are 16 on the upper enclosure and 24 on the base of a B21.

client: A program or collection of programs that makes calls upon the services of a server.

clip map: In the BeeSoft Mapper, a command that clips off extreme values, making the map more efficient and responsive in guiding the robot’s travel decisions.

colliServer: The server software that lets the programmer direct the robot’s movements, or lets the robot travel autonomously, in guarded motion mode.

collision avoidance: A self-protective mode of robotic travel in which the robot automatically tries to avoid those obstacles it can perceive. Every 0.25 seconds, the robot selects a new velocity and heading , based on information from the latest sonar readings, giving it fast enough reaction time to avoid moving obstacles such as passing humans. Velocity is always determined such that no collision will occur in the next 2 seconds. This is called the two second rule.

console: The notebook or laptop computer mounted on the top of the robot.

cost:, One of the pieces of information the robot uses in determining the optimal route to a goal point in global navigation mode. The cost for traversing a particular cell in an occupancy grid is based on that cell’s occupancy value, that is, the likelihood that it is occupied by an obstacle.

cumulative cost: An aggregate value, computed for a particular potential route of robot travel, by iteratively analyzing the individual cost of traversing each grid cell along that route.

dead reckoning: Using the latest wheel encoder readings to determine the robot’s position atany given time relative to its position when it started moving.

drift: The error that accumulates in odometry due to wheel skid and other tracking errors, as the robot continues to move along a heading.

enclosure: The collection of curved panels that enclose the robot’s upper section. Informally, the upper part of the robot.

Ethernet link: A radio link between your robot and a controlling computer remote from it, perhaps on your desktop.

explore mode: A mode of robot travel under global navigation in which the robot proceeds straight to the nearest (in reachability) unexplored area.

global motion: See global navigation.

global navigation: A method of robot travel in which the heading and speed of motion is determined by the calculation of a minimum cost path to a goal point, using occupancy maps.

GNU: Software developed and licensed by the Free Software Foundation; necessary for proper installation of BeeSoft. Linux and BeeSoft are dependent on many utilities developed as part of the GNU project. (Note: BeeSoft comes fully installed with your B14 or B21 robot.)

goal point: In global navigation, a destination for which the robot is headed. Using an occupancy map of its environment, the robot will calculate the minimum cost path to this goal point, or to the nearest point along the path to that location.

grid cell: A unit in a grid-based map, containing a value which indicates the presence or

absence of an obstacle in the corresponding region of the physical environment.

grid-based mapping: A method of mapping that represents environments by two dimensional, evenly spaced grids composed of grid cells.

guarded motion: A mode of robotic travel in which the robot automatically tries to avoid collisions with those obstacles that it can perceive with its sensors.

heading: The direction in which the robot is moving at any given time.

index: To establish the orientation between the base and the enclosure of the robot.

infrared sensor: A sensor that emits Infrared light — light in that part of the electromagneticspectrum above 0.75 millimeters in wavelength. The robot estimates the approximate distance to an obstacle by measuring the intensity of the reflection bounced back from the obstacle’s surface. The B21 robot carries 56 infrared sensors, in two rows; the B14 robot carries 16 infrared sensors, in one row.

joystick: A human-operated control device that allows simultaneous, teleoperated rotation and translation of an autonomous mobile robot. Each RWI, Inc., robot is shipped with a joystick which can be plugged in the robot’s labeled joystick socket. On the B14, this socket is behind the door with the yellow dot on top on the robot’s base. On the B21, the panel containing the joystick socket is set into the yellow-dot door n the base. Special Note: The joystick shipped with your robot has been specially modified to control your robot. It will not work with other equipment or games you might have.

kill reset button: On the B21 robot, the top of two red buttons on the base control panel. On the B14 robot, push either base switch to "on" position to reset.

kill switch: The large, conspicuous red switch(es) on top of the robot. There is one kill switch on top of a B14; on top of the B21, there are two — left and right. Hitting a kill switch immediately stops all robot motion and sets all motors and controls limp. Note: After hitting a kill switch, you cannot resume robot operations through software commands alone. You must press the kill reset button and the system reset button, kill all running servers and then restart all servers.

laser rangefinder: A optional, low-intensity, eye-safe laser on board the robot that detects the proximity of an obstacle by "time of flight" — the time it takes for an invisible, concentrated beam of light to bounce off an obstacle and return. The laser rangefinder measures in the nanosecond (billionths of a second) range. The laser rangefinder itself does not provide angular resolution, but ranging resolution. A precise encoder provides the angular resolution. In sum, the laser rangefinder package provides a much higher angular resolution than the sonar sensors, rendering much more precise measurements, with an average accuracy of plus or minus five centimeters.

(Note: The laser rangefinder is not currently supported by BeeSoft software.)

limp: A condition of the robot’s mechanical apparati — achieved via function calls, or by a human hitting the kill switch — in which the motors can be overridden by hand.

Linux: A completely free re-implementation of POSIX specifications, with SYSV and BSD extensions (meaning it looks like UNIX™ but does not come from the same source code base), available both in source code form and binary form. It is copyrighted by Linus B. Torvalds and other contributors, and is freely redistributable under the terms of the GNU public license. It is not in the public domain, nor is it "shareware."

Linux is one of the operating systems supported by BeeSoft package. Other systems on which BeeSoft can run are Sun/OS (to version 4.x) and Sun/Solaris (version 5.x andhigher), but these are not officially supported by RWI, Inc.

localization: The alignment of a robot’s coordinate system with the global coordinate system of the map of its world.

local motion: Another term for local navigation.

local navigation: A method of robot travel in which the heading and speed of motion is determined by the latest readings from the robot’s sensors.

manipulator, B21: (also called colloquially, arm.)

map: A two-dimensional occupancy grid, constructed in real time using data from the robot’s onboard sensors, as the robot explores its environment. To facilitate ease of use and maintenance, compactness and rapid planning, BeeSoft constructs topological maps on top of grid-based maps.

mapper: See BeeSoft Mapper.

mapping: Constructing a model of the environment based on sensor measurements and, possibly, camera imagery.

map window: The rectangular window on the upper right of the BeeSoft Commander™ display window.

minicom: A Unix-based tty communications program that runs under Linux. Type "man minicom" from a Linux shell for more details.

minimum-cost path: The route to a goal point that carries the lowest cumulative cost.

motion controller board: The electronics that integrates the measurements of the wheel encoders to attempt to estimate the robot’s current position at any time with respect to its original position, that is, where it was when it started rolling. It also controls the motion of the motors that drive the robot’s wheels.

navigation window: The upper left window on the BeeSoft Commander™ display. Used for directing and tracking local navigation.

non-guarded motion: Robotic motion that eschews automatic collision avoidance.

occupancy map: As seen in the map window on the BeeSoft Commanderdisplay, a bird’s eye view of what the robot has seen as it explores its environment. Occupied areas are seen as black; free areas are seen as white.

odometry: The robot’s way of trying to keep track of where it is relative to where it was when it started moving, with the help of its wheel encoders in conjunction with its motion controller board While this measurement is highly accurate for short distances, error can and does accumulate as the robot travels further afield.

orientation: The direction in which the robot is headed.

pan/tilt head: A piece of equipment, controllable in two axes, mounted on top of the robot, that carries one or more cameras.

planner: See BeeSoft Planner.

plan window: The display of the BeeSoft Planner.

position control: This important, ongoing task of the BeeSoft Mapper persistently compensates for accumulated wheel tracking and other errors by continuously matching the robot’s current sonar readings with its global occupancy map. The robot also keeps track of the angular orientation of walls within its purview to correct more accurately for accumulative rotational errors.

POSIX™: An open-standard operating system based on UNIX™.

Procomm™: A commercially available communications program for DOS and Windows™. It is neither supplied nor supported directly by RWI, Inc.

radio link: A pair of data radios that pass RS-232 or Ethernet™ protocol communications from your robot to your desktop workstation.

reachability: In global navigation, the condition of being accessible, by some useable path, to the robot. The degree of reachability is used to determine the relative nearness of a particular goal point.

robot: In general, an electro-mechanical entity equipped with sensory apparati and manipulative appurtenances, designed to perform routine or repetitive tasks, or to operate in environments lethal or dangerous to humans. The term robot was adapted from the Czech word robota, meaning forced labor, by Czech novelist and dramatist Karel Èapek in his dystopian 1920 play, R.U.R. (Rossum’s Universal Robots), a work exploring the dangers of technological progress.

rotation: Leftward or rightward motion, centered on the robot’s axis. Can be done either in place, or in conjunction with translation.

security distance: A value added to the actual, physical diameter of the robot to give it a built in buffer zone, forcing collision avoidance algorithms to think the robot is somewhatlarger than it actually is.

sensor: An electro/mechanical, electrical, optical or other device that detects, measures and/or records information about phenomena in its surroundings and conveys that data in a useable form to a human, computer, or other entity that is prepared to use it. BeeSoft uses several kinds of sensors: sonars, infrareds, tactiles, lasers and cameras.

smart panel™: Another term for bump panel.

sonar sensor: An ultrasonic transducer that generates a sonic, or sound, wave — called a ping — that travels outwards in an expanding cone, and listens for an echo. For each reading, the total time between the generation of the ping and the receipt of the echo, coupled with the speed of sound in the robot’s environment, generates an estimate of the distance to the object that bounced back the echo. The B14 robot carries 16 sonars; the B21 carries 24.

speech synthesizer: A device, used optionally in the B14 and B21 robots, that incorporates both hardware and software elements and converts digitally encoded data into recognizable, human-like speech.

specular reflection: An anomaly that can occur when a sonar sensor’s ping bounces off an obliquely-angled object onto another object in the environment, which then, in turn, returns an echo to the sonar. This effect can bedevil the sonars, causing them to overestimate the distance between the robot and the nearest obstacle.

system reset button: On the B21 robot, the bottom of two red buttons on the base control panel.

tactile sensor: The more formal term for bump switch.

target point: In local navigation, the location to which the robot is headed, expressed relative to its current location.

TCXHOST: The computer on which tcxServer is running.

tcxServer: The low-level software server that manages communication among all programs running on all computers in the robot system.

teleoperation: "Hands off" direction of the robot’s movements, via user program control or through the BeeSoft Commander.

terminal: A generic term for any communications software package that you can use to communicate with an RWI, Inc. robot. Terminal-type software can be found on manysystems in many forms. Consult the system administrator at your site for information of what kinds of communication programs are supported at your site.

topological map: The product of a method of mapping that represents the physical environment in graphs. Nodes in the graphs correspond to distinct situations, places or landmarks (such as doorways), and connected by arcs if a direct path exists between them. Topological maps are more compact than grid-based maps, and thus facilitate rapid planning.

translation: Forward or rearward motion of the robot, along the heading to which it is currently directed.

two second rule: A standard in BeeSoft collision avoidance mode that requires the robot to adjust its velocity so that, at any given instant in time, no collision will occur within the next two seconds.

unexplored area: Unmapped area.

velocity: The speed at which the robot moves along its heading. The maximum speed for the B14 and B21 robots is approximately 90 cm/sec.

wheel encoders: Devices in the robot base that keep track of the revolutions of the robot’s wheels. Used for odometry.

wheel skid: Errors in robot wheel tracking, caused by routine hazards in real-world research and operational environments such as slippery floors, carpeting, doorjambs, and the like. These errors are mitigated somewhat by the redundancy and crosschecking supplied by the robot’s other sensors.

world size: In the BeeSoft Mapper™, the overall dimensions of the map the robot uses for global navigation. Usually set to 45 meters.

X-Window System™: A portable, network-transparent window system that runs on a wide range of computing and graphics machines. X Window System is a trademark of X Consortium, Inc.

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