Parallax Boe-Bot Whisker Kit User manual

Parallax, Inc
http://www.parallaxinc.com
http://www.stampsinclass.com
WhiskerKitInstructions(June2000) •Page1
Whisker Kit Instructions (#28134)
InstructionsforusingbumperswitcheswithyourParallaxBoe-Bot
Thebumperswitchesinthiskitlooklikewhiskers(orantennae)whenthey’remountedontheBoe-Bot. Whiskers
increase the Boe-Bot’s ability to sense the world around it by giving it tactile sensitivity. The Boe-Bot can use
these whiskers to navigate only by touch. Whiskers can also be used along with either or both of the Boe-Bot’s
twotypesofsight,lightintensityand/orobjectdetection.
Boe-Botwithwhiskers1
PartsList
VerifythatyourWhiskerKithasallcomponentslisted
below. Parallaxpart numbers are includedin case you
wanttoreplaceorreorderanyofthepieces.
•(2)10Kohmresistors(#150-01030)
•(2)3-pinheaders(#451-00303)
•(2)3/8”4/40male/femalestandoffs(#700-00049)
•(2)¼”4/40sizescrews(#700-00028)
•(2)Boe-Botbumperwires(#700-00010)
•(2)Nylonwasherssize#4(#700-00015)
1Pictured Boe-Bot is using the Board of Education Rev. B, due for release in July 2000. The Board of Education Rev. B. has
built-in servo connects and power supply capacitors. The power supply capacitors replace the large 3300 uF capacitor that
was required with the Board of Education Rev A.

Parallax, Inc
http://www.parallaxinc.com
http://www.stampsinclass.com
WhiskerKitInstructions(June2000) •Page2
HardwareandCircuits
Belowisawhiskerdiagramincaseyoudecidetobuildyourown. Anyfirmyetspringywirewilldothejob.
Whiskersare justphysicalextensionsthatactuate normally openswitches,andthey’reeasy to build. Here’show:
(a) Removethetwofrontscrewsthathold
yourBoardofEducationtothefront
standoffs.
(b) Screwinthemale/femalestandoffs
includedin the whiskerskit in placeof
thescrewsthatwereremovedinstep(a).
(c) Sandwichtheopenendedloopofeach
whiskerbetweenthetopofthestandoff
andthenylonwashersincludedinthekit.
(d) Usethescrewsfromstep(a)toattach
thenylon washers andwhiskers to the
standoffsfromstep(b).
(e) Eachwhisker should hang over the
breadboardsothatitcouldtouchoneof
thethreepinheaderswhenpressed. See
Whiskersdiagram.
Whiskerswiringdiagram(notethatthethree-pinheaderhasbeen
cutdowntotwo-pinsizeinthisdrawing)
TheWhiskerschematicsare shown below. This schematic does notshowtheservos. Ifyou want to use the sample
codeonthenextpage,makesuretoalsoconnecttheservocontrollinestoP14(rightservo)andP15(leftservo).

Parallax, Inc
http://www.parallaxinc.com
http://www.stampsinclass.com
WhiskerKitInstructions(June2000) •Page3
BASICStampBoe-BotNavigationUsingWhiskers
Whiskers.bs2is a simpleroaming program example thatuses Whiskers insteadof infrared for objectdetection.
This program listing makes the Boe-Bot travel straight ahead while monitoring the whiskers to see if they have
bumpedintoanobstacle. Assoonasanobstacleisdetected,theBoe-Botbacksup,turns,andcontinuesforward
untilanotherobstacleisencountered.
When a whisker is pressed,due to anobstacle, the normallyopen switch closes. When thishappens, the output
signalgoesfromhightolow.I/Opins P10 andP5aresetto input andusedtomonitorthe states oftheseswitches.
Thetwowhiskersmaybeinoneoffourstates:
(1) Bothhigh–noobjectsdetected
(2) Leftlow,righthigh–objectdetectedontheleft,turnright.
(3) Rightlow,lefthigh–objectdetectedontheright,turnleft.
(4) Bothlow–indicatesahead-oncollisionwithawideobjectsuchasawall.
' Whiskers.bs2 - Simple program for detecting objects
' with a BASIC Stamp II in a Boe-Bot
' Constant and Variable Definitions
'-----------------------------------------------------------------------------------
servo_left con 15 ' left servo on P15
servo_right con 14 ' right servo on P15
whisker_left var in10 ' left whisker on P10
whisker_right var in5 ' right whisker on P5
counter var word ' loop counter variable
' Main Program
'-----------------------------------------------------------------------------------
check_whiskers: ' check each whisker
if whisker_left = 0 and whisker_right = 0 then back
if whisker_left = 0 then right
if whisker_right = 0 then left
drive_servos: ' drive forward
pulsout servo_left,850
pulsout servo_right,650
pause 10
goto check_whiskers
back: ' backwards if both switches close
for counter = 0 to 100
pulsout servo_left,650
pulsout servo_right,850
next
return
goto drive_servos
left: ' turn left if right switch closes
gosub back
for counter = 0 to 50
pulsout servo_left,650
pulsout servo_right,650
next
goto drive_servos

Parallax, Inc
http://www.parallaxinc.com
http://www.stampsinclass.com
WhiskerKitInstructions(June2000) •Page4
right: ' turn right if left switch closes
gosub back
for counter = 0 to 50
pulsout servo_left,850
pulsout servo_right,850
next
goto drive_servos
'-----------------------------------------------------------------------------------
WhiskersTips
Problem PossibleSolution
Boe-Botbacksuptoofar/notfarenough.
Boe-Botturnstoofar/notfarenough. Adjust thefor. . . nextargumentsintheprogram listing. They may be increased or decreased to
increase or decrease how far the Boe-Bot rotates
whenitturnsaswellashowfaritbacksup.
Boe-Botdrivesupsideofwallbecausewhiskers
didn’tcatchholdofanobject. Increasetheresistanceofawhisker against the surfaceofanobjectbybendingwhiskersin adifferent
angle. Alternatively,try dipping thewhiskersin a
coatingmaterialsuchasrubbercement.
Dead-centerobjectisn’tdetectedbywhiskers. Bendwhiskersinward.
Robotgetsstuckincorners. Try therandomcommandtodecidewhethertoturn
leftorrightafterhittinganobject.
Switchesdon’tappeartoworkproperly. Checkyourwiringandconnections. UsetheDebug
terminaltodisplaythestateofthebumperswitches
as seen by theBASIC Stamp2. This can be doneby
replacing the contents of thecheck_whiskersroutine
withthefollowingsegmentofcode:
check_whiskers:
debug home
debug bin ? in5
debug bin ? in10
goto check_whiskers
Note: WhenabumperispressedtheDebugterminal
shoulddisplaya0insteadofa1.