LEGO MINDSTORMS Robots User Manual

Page 205
Figure 10-2.
Hank, retrofitted with a light sensor
• avoid() is the highest-level behavior. It is triggered by the bumpers and does the standard back-up-and-turn.
Convincing Hank to seek light is surprisingly hard. You can, of course, implement your own algorithm in seek_enlightenment(). It's a neat feature of subsumption architecture that you can
concentrate solely on light-seeking behavior in seek_enlightenment(). The obstacle avoidance behavior is already programmed in a different behavior and will subsume the light-seeking
behavior as necessary.
Without further ado, here's the entire program, LightSeeker.c:
#include "conio.h"
#include "direct-button.h"
#include "direct-motor.h"
#include "direct-sensor.h"
#include "unistd.h"
#include "sys/tm.h"
#define MAX_TASKS 32
pid_t pid[MAX_TASKS];
int task_index;
#define BACK_TIME 500
#define TURN_TIME 800
// Motor commands.
#define COMMAND_NONE -1
#define COMMAND_FORWARD 1

LEGO MINDSTORMS Robots Specifications

General

Product Line	LEGO MINDSTORMS
Category	Toy
Age Range	10+
Batteries Required	Yes
Memory	64 MB RAM, 16 MB Flash
Connectivity	Bluetooth, USB
Sensors	Touch, Color, Gyro
Battery Type	AA
Interactive Features	Programmable, Remote Control
App Compatibility	iOS, Android
Processor	ARM9
Pieces Count	601
Battery Count	6
App Name	LEGO MINDSTORMS EV3 Programmer App