root / demos / hunter_prey / src / main.c @ 1828
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/*
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* Hunter-Prey main.c File - Implementation of Hunter-Prey behavior which
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* uses finite state machines to manage the behavior. A top level
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* state machine controls the high level behavior switches between
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* "hunter" and "prey" and manages the wireless communication. Two
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* additional state machines control the behavior of the robot when
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* it is in "prey" mode and when it is in "hunter" mode.
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*
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* Author: John Sexton, Colony Project, CMU Robotics Club
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*/
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#include <dragonfly_lib.h> |
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#include <wl_basic.h> |
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#include "hunter_prey.h" |
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#include "encoders.h" |
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#define WL_CHANNEL 24 |
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#define BACK_THRESHOLD -1000 |
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#define TURN_DIST 1024 |
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#define IR_DIST_THRESHOLD 150 |
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#define WAIT_DELAY_MS 2000 |
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/* State Macros */
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/* Top Level FSM States */
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#define TOP_INIT 0 |
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#define TOP_HUNTER_HUNT 1 |
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#define TOP_HUNTER_TAG 2 |
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#define TOP_HUNTER_PURSUE 3 |
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#define TOP_PREY_AVOID 4 |
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#define TOP_HUNTER_WAIT 5 |
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#define TOP_ERROR 6 |
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/* Hunter FSM States */
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#define HUNTER_SPIRAL 0 |
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#define HUNTER_CHASE 1 |
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/* Prey FSM States */
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#define PREY_START_BACK 0 |
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#define PREY_BACKING 1 |
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#define PREY_TURN 2 |
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#define PREY_AVOID 3 |
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/* Function prototype declarations */
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int hunter_FSM(int, int, int); |
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int prey_FSM(int); |
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/* Variables used to receive packets */
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unsigned char* packet_data; |
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int data_length;
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/* Data buffer used to send packets */
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char send_buffer[2]; |
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int main(void) |
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{
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/* Initialize dragonfly board */
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dragonfly_init(ALL_ON); |
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xbee_init(); |
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encoders_init(); |
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/* Initialize the basic wireless library */
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wl_basic_init_default(); |
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/* Set the XBee channel to assigned channel */
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wl_set_channel(WL_CHANNEL); |
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/* ****** CODE HERE ******* */
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/* Initialize state machines */
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int state = TOP_INIT;
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int hunter_state = HUNTER_SPIRAL;
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int prey_state = PREY_AVOID;
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int frontIR = 0; |
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int maxBOM = 0; |
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int robotID = get_robotid();
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int oldTime = 0, curTime = 0; |
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while (1) { |
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/* Check if we've received a wireless packet */
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packet_data = wl_basic_do_default(&data_length); |
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/* Top level state machines */
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switch(state) {
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case TOP_INIT:
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orbs_set_color(RED, GREEN); |
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delay_ms(500);
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orbs_set_color(GREEN, RED); |
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delay_ms(500);
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/* Allow user to pick the starting behavior */
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if (button1_read()) {
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state = TOP_PREY_AVOID; |
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prey_state = PREY_AVOID; |
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} else {
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state = TOP_HUNTER_HUNT; |
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hunter_state = HUNTER_SPIRAL; |
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} |
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break;
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case TOP_HUNTER_HUNT:
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orbs_set_color(RED, RED); |
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if (packet_data && data_length == 2 |
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&& packet_data[0] == HUNTER_PREY_ACTION_ACK) {
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/* If we've received an ACK, we need to wait */
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state = TOP_HUNTER_WAIT; |
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} else {
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/* Record some sensor readings and check if we can TAG */
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bom_refresh(BOM_ALL); |
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frontIR = range_read_distance(IR2); |
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maxBOM = get_max_bom(); |
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if (hunter_prey_tagged(maxBOM, frontIR)) {
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state = TOP_HUNTER_TAG; |
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} else {
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/* If we haven't tagged, then enter hunter FSM */
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hunter_state = hunter_FSM(hunter_state, maxBOM, frontIR); |
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} |
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} |
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break;
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case TOP_HUNTER_TAG:
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orbs_set_color(RED, PURPLE); |
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if (packet_data && data_length == 2 |
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&& packet_data[0] == HUNTER_PREY_ACTION_ACK) {
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/* If we've received an ACK, then someone beat us to the TAG and
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* we need to wait. */
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state = TOP_HUNTER_WAIT; |
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} else {
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/* Prepare and send the TAG packet */
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send_buffer[0] = HUNTER_PREY_ACTION_TAG;
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send_buffer[1] = robotID;
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wl_basic_send_global_packet(42, send_buffer, 2); |
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/* Record the time so we don't spam a TAG message on the network */
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oldTime = rtc_get(); |
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state = TOP_HUNTER_PURSUE; |
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} |
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break;
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case TOP_HUNTER_PURSUE:
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orbs_set_color(RED, BLUE); |
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curTime = rtc_get(); |
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if (packet_data && data_length == 2 |
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&& packet_data[0] == HUNTER_PREY_ACTION_ACK) {
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/* Check if we've received a new wireless packet */
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if (packet_data[1] == robotID) { |
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/* We've been ACKed, so we can now become the prey */
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state = TOP_PREY_AVOID; |
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prey_state = PREY_START_BACK; |
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} else {
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/* If we get an ACK with a different robotID, then someone beat us
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* to the TAG, so we must wait */
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state = TOP_HUNTER_WAIT; |
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} |
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} else if (curTime - oldTime > 1) { |
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/* If 1 second has ellapsed, return to normal hunting state (we can
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* TAG again now) */
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state = TOP_HUNTER_HUNT; |
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} else if (oldTime > curTime) { |
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/* If for some reason the timer overflows, or the wireless library
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* (which is also using the same timer) resets the timer,
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* reinitialize the timer so that we don't wait too long for the
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* timer to catch back up. */
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oldTime = curTime; |
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} else {
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/* If no other behavioral changes need to be made, then continue
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* with the hunter FSM where we left off */
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bom_refresh(BOM_ALL); |
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frontIR = range_read_distance(IR2); |
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maxBOM = get_max_bom(); |
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hunter_state = hunter_FSM(hunter_state, maxBOM, frontIR); |
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} |
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break;
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case TOP_PREY_AVOID:
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orbs_set_color(GREEN, GREEN); |
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if (packet_data && data_length == 2 |
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&& packet_data[0] == HUNTER_PREY_ACTION_TAG) {
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/* Check if we've received a TAG yet. If so then send an ACK back */
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send_buffer[0] = HUNTER_PREY_ACTION_ACK;
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send_buffer[1] = packet_data[1]; |
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wl_basic_send_global_packet(42, send_buffer, 2); |
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state = TOP_HUNTER_WAIT; |
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} else {
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/* If we haven't received a TAG yet, continue with prey FSM */
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bom_on(); |
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prey_state = prey_FSM(prey_state); |
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} |
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break;
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case TOP_HUNTER_WAIT:
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/* Set orb colors and wait to give the prey the 5 second head start */
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orbs_set_color(BLUE, BLUE); |
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bom_off(); |
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motors_off(); |
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delay_ms(WAIT_DELAY_MS); |
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state = TOP_HUNTER_HUNT; |
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hunter_state = HUNTER_SPIRAL; |
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break;
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case TOP_ERROR:
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default:
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orbs_set_color(PURPLE, PURPLE); |
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state = TOP_ERROR; |
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while(1); |
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break;
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} |
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} |
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/* ****** END HERE ******* */
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while(1); |
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return 0; |
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} |
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/*
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* prey_FSM - Prey finite state machine which starts by backing away, turning,
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* and then running and avoiding obstacles.
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*
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* Arguments:
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* prey_state - Current prey state.
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*
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* returns - The new state of the prey state machine.
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*/
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int prey_FSM(int prey_state) { |
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/* Variable to store the front rangefinder readings */
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int rangeVals[3] = {0, 0, 0}; |
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switch (prey_state) {
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case PREY_START_BACK:
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motor_l_set(BACKWARD, 255);
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motor_r_set(BACKWARD, 255);
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encoder_rst_dx(LEFT); |
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encoder_rst_dx(RIGHT); |
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return PREY_BACKING;
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break;
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case PREY_BACKING:
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if (encoder_get_x(LEFT) < BACK_THRESHOLD
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|| encoder_get_x(RIGHT) < BACK_THRESHOLD) {
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motor_l_set(BACKWARD, 255);
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motor_r_set(FORWARD, 255);
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encoder_rst_dx(LEFT); |
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encoder_rst_dx(RIGHT); |
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return PREY_TURN;
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} else {
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return PREY_BACKING;
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} |
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break;
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case PREY_TURN:
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if (encoder_get_x(LEFT) < -TURN_DIST
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|| encoder_get_x(RIGHT) > TURN_DIST) {
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return PREY_AVOID;
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} else {
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return PREY_TURN;
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} |
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break;
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case PREY_AVOID:
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rangeVals[0] = range_read_distance(IR1);
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rangeVals[1] = range_read_distance(IR2);
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rangeVals[2] = range_read_distance(IR3);
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/* Drive away if we detect obstacles using the rangefinders */
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if (rangeVals[1] > 0 && rangeVals[1] < IR_DIST_THRESHOLD) { |
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if (rangeVals[0] < rangeVals[2]) { |
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motor_l_set(FORWARD, 255);
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motor_r_set(BACKWARD, 255);
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} else {
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motor_l_set(BACKWARD, 255);
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motor_r_set(FORWARD, 255);
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} |
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return PREY_AVOID;
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} else if (rangeVals[0] > 0 && rangeVals[0] < IR_DIST_THRESHOLD) { |
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motor_l_set(FORWARD, 255);
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motor_r_set(FORWARD, 170);
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return PREY_AVOID;
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} else if (rangeVals[2] > 0 && rangeVals[2] < IR_DIST_THRESHOLD) { |
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motor_l_set(FORWARD, 170);
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motor_r_set(FORWARD, 255);
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return PREY_AVOID;
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} else {
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motor_l_set(FORWARD, 255);
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motor_r_set(FORWARD, 255);
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return PREY_AVOID;
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} |
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break;
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default:
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return PREY_AVOID;
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break;
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} |
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return prey_state;
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} |
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/*
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* hunter_FSM - Hunter finite state machine which defaults to spiraling
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* outwards until the BOM can locate the prey. Once the BOM locates
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* the prey, chase the prey as fast as possible.
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*
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* Arguments:
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* hunter_state - Current hunter state.
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* maxBOM - Current maximum BOM value.
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* frontIR - Current front IR rangefinder reading value.
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*
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* returns - The new state of the hunter state machine.
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*/
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int hunter_FSM(int hunter_state, int maxBOM, int frontIR) { |
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switch(hunter_state) {
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case HUNTER_SPIRAL:
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if (maxBOM != -1) { |
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return HUNTER_CHASE;
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} else {
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motor_l_set(FORWARD, 170);
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motor_r_set(FORWARD, 190);
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return HUNTER_SPIRAL;
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} |
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break;
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case HUNTER_CHASE:
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if (maxBOM == -1) { |
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return HUNTER_CHASE;
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} else if (maxBOM == 4) { |
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motor_l_set(FORWARD, 255);
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motor_r_set(FORWARD, 255);
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return HUNTER_CHASE;
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} else if (maxBOM == 3) { |
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motor_l_set(FORWARD, 255);
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motor_r_set(FORWARD, 240);
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return HUNTER_CHASE;
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} else if (maxBOM == 5) { |
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motor_l_set(FORWARD, 240);
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motor_r_set(FORWARD, 255);
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return HUNTER_CHASE;
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} else if (maxBOM < 3) { |
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motor_l_set(FORWARD, 255);
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motor_r_set(FORWARD, 170);
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return HUNTER_CHASE;
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} else if (maxBOM > 5 && maxBOM <= 8) { |
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motor_l_set(FORWARD, 170);
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motor_r_set(FORWARD, 255);
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return HUNTER_CHASE;
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} else if (maxBOM > 8 && maxBOM < 12) { |
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motor_l_set(BACKWARD, 255);
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motor_r_set(FORWARD, 255);
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return HUNTER_CHASE;
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} else {
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motor_l_set(FORWARD, 255);
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motor_r_set(BACKWARD, 255);
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return HUNTER_CHASE;
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} |
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break;
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default:
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return HUNTER_SPIRAL;
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break;
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} |
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return hunter_state;
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} |