Parallax Boe-Bot User Manual

Chapter 6: Light Sensitive Navigation with Photoresistors · Page 203
Figure 6-6: Modify RoamingWithPhotoresistorDividers.bs2
' Excerpt from
' RoamingWithPhotoresistor
' Dividers.bs2
IF (IN6 = 0) AND (IN3 = 0) THEN
GOSUB Back_Up
GOSUB Turn_Left
GOSUB Turn_Left
ELSEIF (IN6 = 0) THEN
GOSUB Back_Up
GOSUB Turn_Right
ELSEIF (IN3 = 0) THEN
GOSUB Back_Up
GOSUB Turn_Left
ELSE
GOSUB Forward_Pulse
ENDIF
' Modified excerpt from
' RoamingWithPhotoresistor
' Dividers.bs2
IF (IN6 = 0) AND (IN3 = 0) THEN
GOSUB Back_Up
' GOSUB Turn_Left
' GOSUB Turn_Left
ELSEIF (IN6 = 0) THEN
' GOSUB Back_Up
GOSUB Turn_Right
ELSEIF (IN3 = 0) THEN
' GOSUB Back_Up
GOSUB Turn_Left
ELSE
GOSUB Forward_Pulse
ENDIF
√ Modify RoamingWithPhotoresistorDividers.bs2 as shown in the right side of
Figure 6-6.
√ Run the program, and compare the performance.
ACTIVITY #3: A MORE RESPONSIVE SHADOW CONTROLLED BOE-BOT
By eliminating the FOR…NEXT loops in the navigation subroutines, you can make the Boe-
Bot significantly more responsive. This wasn’t really possible with the whiskers, because
the Boe-Bot had to back up before turning since it had already made physical contact
with the obstacle. When you are using shadows to guide the Boe-Bot, it can check
between each pulse to see if the shadow is still detected regardless of whether it’s moving
forward or executing a maneuver.
A Simple Shadow Controlled Boe-Bot
One interesting form of remote control is to have the Boe-Bot sit still in normal light,
then follow a shadow you cast over the photoresistors. It’s kind of a user-friendly way of
guiding the Boe-Bot’s motion.
Example Program – ShadowGuidedBoeBot.bs2
When you run this next program, the Boe-Bot should stay still when no shadow is cast
over its photoresistor dividers. When you cast a shadow over both photoresistors, the

Parallax Boe-Bot Specifications

General

Brand	Parallax
Model	Boe-Bot
Category	Robotics
Language	English