James Hilder
Psi Swarm Code V0.41 [With Beautiful Meme program]
Dependencies: PsiSwarmLibrary mbed
Fork of
BeautifulMemeProjectBT
by 
Alan Millard
Diff: beacon.cpp
- Revision:
- 30:513457c1ad12
- Parent:
- 29:9756004e8499
--- a/beacon.cpp Thu Mar 03 23:22:01 2016 +0000
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,376 +0,0 @@
-/// PsiSwarm Beautiful Meme Project Source Code
-/// Version 0.4
-/// James Hilder, Alan Millard, Homero Elizondo, Jon Timmis
-/// University of York
-
-// beacon.cpp - Functions for detecting the beacon and taking IR readings of the robots
-
-#include "main.h"
-
-int pulse_step = 1; //Pulse-step corresponds to which timeslot (0-9) is currently active, where beacon=0 and robots=2-8
-int low_threshold; //Set to be 2x mean background IR
-int beacon_threshold; //Set to be 4x mean background IR
-unsigned short ir_sensor_data[9][8]; // The raw sensor data from all 9x 50ms sample windows
-Ticker ir_sample_ticker; // Ticker for the IR data sampling and processing; runs every 50ms in middle of timeslot
-Ticker ir_emitter_ticker; // Ticker for turning on the IR emitters; runs every 50ms near start of timeslot
-Timeout ir_emitter_timeout; // Timeout for turning off the IR emitters after 40ms
-Timer beacon_debug_timer; // Timer for debug information only [remove later?]
-
-char show_ir_debug_info = 0; // Set to 1 to display (via PC) the list of IR readings & visible robots every timestep
-
-/// The locate beacon function samples the IR radiation from all 8 side sensors over a period of 1 second in [BEACON_PERIOD / 2.5] (20ms) blocks.
-/// The infrared beacon is set to give a 50ms burst of IR every 500ms. We should thus see in the sampled radiation 2 blocks
-/// of samples, 2 or 3 samples in duration, when a significant peak occurs; the blocks should be 25 samples apart.
-void locate_beacon()
-{
- int sample_period = (BEACON_PERIOD * 2) / 5;
- out("1) Searching for IR beacon...");
- unsigned short samples[50][9];
- Timer beacon_timer;
- beacon_timer.start();
- int offset = 0;
- //This loop samples the background IR values at 50Hz for 1 second and stores in an array
- for(int i=0; i<50; i++) {
- store_background_raw_ir_values ();
- if(i%2 == 0){
- set_center_led(1, 0.5);
- set_leds(0xAA,0x55);
- }else{
- set_center_led(2, 0.5);
- set_leds(0x55,0xAA);
- }
- samples[i][8]=0;
- for(int j=0; j<8; j++) {
- samples[i][j] = get_background_raw_ir_value(j);
- samples[i][8] += get_background_raw_ir_value(j);
- }
- offset+=sample_period;
- while(beacon_timer.read_us() < offset) {}
- }
-
- //Print values: for testing [comment out]
- /*
- for(int i=0; i<50; i++) {
- out("IR %d:",i);
- for(int j=0; j<8; j++) {
- out("[%d:%d]",j,samples[i][j]);
- }
- out(" [SUM:%d]\n",samples[i][8]);
- }
- */
-
- //Bubble sort sums to find (6) highest values
- unsigned short sorted_array[50];
- for(int i=0; i<50; i++) {
- sorted_array[i]=samples[i][8];
- }
- for (int c = 0 ; c < 49; c++) {
- for (int d = 0 ; d < (50-c-1); d++) {
- if (sorted_array[d] > sorted_array[d+1]) {
- unsigned short swap = sorted_array[d];
- sorted_array[d] = sorted_array[d+1];
- sorted_array[d+1] = swap;
- }
- }
- }
-
- //Print sorted values: for testing [comment out]
- /*
- out("Sorted values:");
- for (int c = 0 ; c < 50 ; c++ ) {
- out("%d", sorted_array[c]);
- if(c<49)out(",");
- }
- out("\n");
- */
-
- // Calculate mean background sum value by looking at 44 lowest sum values
- int background_mean = 0;
- for(int i=0;i<44;i++)background_mean += sorted_array[i];
- background_mean /= 44;
-
- //out("Background mean value: %d\n",background_mean);
-
- //Our beacon threshold will be 4x the background mean value; find all instances where this occurs
- low_threshold = background_mean * 2;
- beacon_threshold = background_mean * 4;
- char beacon_detected_indices[50];
- for(int i=0;i<50;i++){
- if(samples[i][8] > beacon_threshold) beacon_detected_indices[i]=1;
- else beacon_detected_indices[i]=0;
- }
- //Count and display matches
- int beacon_detected_count = 0;
- //char output_string[251] = "";
- for(int i=0;i<50;i++){
- if(beacon_detected_indices[i] == 1){
- beacon_detected_count++;
- // char index_string[6];
- // sprintf(index_string,"[%d],",i);
- // strcat(output_string,index_string);
- }
- }
- //out("%d samples are above threshold:%s\n",beacon_detected_count,output_string);
-
- //We will use this array to store average values for each sensor when the beacon is detected
- unsigned short beacon_averages[8];
- char beacon_averages_count = 0;
- for(int i=0;i<8;i++)beacon_averages[i]=0;
-
- //Now determine if the beacon is correctly found: must adhere to a set of rules
- //Firstly, we should have not less than 4 and not more than 6 positive matches
- if(beacon_detected_count>3 && beacon_detected_count<7){
- // Now verify that the positive samples are in valid places...
- // Find first positive sample
- int first_index = 0;
- //out("Here\n",first_index);
-
- while(beacon_detected_indices[first_index]==0)first_index ++;
-
- //out("First index:%d\n",first_index);
-
-
- // Check if first index is zero: if so, we need to check index 49 (and 48) to see if they are also high
- if(first_index == 0){
- if(beacon_detected_indices[49]>0)first_index = 49;
- if(beacon_detected_indices[48]>0)first_index = 48;
- }
-
- beacon_averages_count++;
- for(int i=0;i<8;i++){beacon_averages[i]+=samples[first_index][i];}
-
- // Now count the length of the 'block' of positive hits: must be equal to 2 or 3
- char block_length = 1;
- int end_index = first_index + 1;
- if(end_index == 50) end_index = 0;
- while(beacon_detected_indices[end_index]>0){
- beacon_averages_count++;
- for(int i=0;i<8;i++){beacon_averages[i]+=samples[end_index][i];}
- block_length ++;
- end_index ++;
- if(end_index == 50) end_index = 0;
- }
- if(block_length==2 || block_length == 3){
- //We have found the first correct block and it is valid; now calculate its mid-point and check that the second block is also present 500ms later
- float mid_point;
- char second_block_okay = 0;
- if(block_length == 2){
- mid_point = first_index + 0.5;
- char second_block_low = first_index + 25;
- char second_block_high = first_index + 26;
- if(second_block_low > 49) second_block_low -= 50;
- if(second_block_high > 49) second_block_high -= 50;
- beacon_averages_count+=2;
- for(int i=0;i<8;i++){beacon_averages[i]+=samples[second_block_low][i]+samples[second_block_high][i];}
- if(beacon_detected_indices[second_block_low]>0 && beacon_detected_indices[second_block_high]>0) second_block_okay = 1;
- }
- if(block_length == 3){
- mid_point = first_index + 1;
- if(mid_point == 50) mid_point = 0;
- char second_block_single = first_index + 26;
- if(second_block_single > 49) second_block_single -= 50;
- beacon_averages_count++;
- for(int i=0;i<8;i++){beacon_averages[i]+=samples[second_block_single][i];}
- if(beacon_detected_indices[second_block_single]>0) second_block_okay = 1;
- }
- if(second_block_okay >0){
- beacon_found = 1;
- beacon_heading = get_bearing_from_ir_array(beacon_averages);
- out("Found at %d degrees\n",beacon_heading);
- //for(int i=0;i<8;i++){
- // beacon_averages[i] /= beacon_averages_count;
- // out("[%d]",beacon_averages[i]);
- //}
- out("2) Synchronising...\n");
- // Calculate the offset to the expected start of the next beacon pulse
- int microseconds_offset = (sample_period * mid_point) - sample_period - (sample_period / 4);
- //out("MS Offset:%d Midpoint:%f\n Current Time:%d\n",microseconds_offset,mid_point,beacon_timer.read_us());
- int cycle_period = (BEACON_PERIOD * 10);
- if(microseconds_offset < 0) microseconds_offset += cycle_period;
- //If we have missed the start of the beacon this cycle, wait until the next cycle
- while(beacon_timer.read_us()% (cycle_period) > microseconds_offset){};
- //Now wait until the start of the beacon pulse
- while(beacon_timer.read_us()% (cycle_period) < microseconds_offset){};
- /*
- out("Now:%d",beacon_timer.read_us());
- Timer test_timer;
- test_timer.start();
- for(int i=0;i<50;i++){
- store_background_raw_ir_values ();
- out("Time %d: %d\n",test_timer.read_ms(),get_background_raw_ir_value(2));
- while(test_timer.read_ms() % 10 < 9){};
- }
- */
- }else{
- beacon_found = 0;
- out("Beacon not found: a matching second block %dms after first block not detected\n",(BEACON_PERIOD / 100));
- }
- }else{
- beacon_found = 0;
- if(block_length == 1) out("Beacon not found: a single sample [%d] was high but not its neighbours\n",first_index);
- if(block_length > 3) out("Beacon not found: a block of %d high samples was detected\n",block_length);
- }
- } else {
- beacon_found = 0;
- if(beacon_detected_count > 6) out("Beacon not found: too many high samples [%d]\n",beacon_detected_count);
- else out("Beacon not found: too few high samples [%d]\n",beacon_detected_count);
- }
- if(beacon_found == 0){
- set_leds(0x00,0x00);
- set_center_led(1, 1);
- display.clear_display();
- display.set_position(0,0);
- display.write_string("BEACON NOT FOUND");
- }
-}
-
-// The start_infrared_timers() function is called as soon as the beacon has been detected and synchronised to
-// It launches 2 tickers at offset times; the first is responsible for turning the robots IR emitters on in its proper timeslot
-// The other reads the values given from the IR sensor in the middle of each timeslot and processes that information in the final timeslot
-void start_infrared_timers()
-{
- // At this point we should be exactly at the start of a beacon cycle.
- // We want the emitter ticker to start in approx 5ms (this will let us set a 40ms pulse)
- // We want the sample ticker to start in approx 25ms (this will let us sample in the middle each step
- out("3) Starting TDMA infrared timers\n");
- beacon_debug_timer.start();
- wait_us(BEACON_PERIOD / 10);
- ir_emitter_ticker.attach_us(emitter_ticker_block,BEACON_PERIOD);
- wait_us(((BEACON_PERIOD * 4) / 10)); //Wait for middle of pulse
- ir_sample_ticker.attach_us(sample_ticker_block,BEACON_PERIOD);
-}
-
-
-//Return the max value in IR array
-unsigned short get_highest_sample(unsigned short * ir_array){
- unsigned short highest = 0;
- for(int i=0;i<8;i++){
- if(ir_array[i]>highest) highest=ir_array[i];
- }
- return highest;
-}
-
-//Return the sum total of IR array
-unsigned short get_sum_sample(unsigned short * ir_array){
- unsigned short sum = 0;
- for(int i=0;i<8;i++){
- sum+=ir_array[i];
- }
- return sum;
-}
-
-//The emitter_ticker_block function runs every 50ms and turns the IR emitters on when pulse_step-1 matches the robot ID
-//It then starts a timeout to run emitter_timeout_block after 40ms, which turns off the emitters
-void emitter_ticker_block(){
- //If the time-step (-1) equals my ID, turn on my emitters for 40ms
- if(pulse_step-1 == robot_id && disable_ir_emitters == 0){
- IF_set_IR_emitter_output(0, 1);
- IF_set_IR_emitter_output(1, 1);
- ir_emitter_timeout.attach_us(emitter_timeout_block,(BEACON_PERIOD * 8)/10);
- }
-}
-
-//Turn off the emitters
-void emitter_timeout_block(){
- //Turn off IR emitters
- IF_set_IR_emitter_output(0, 0);
- IF_set_IR_emitter_output(1, 0);
-}
-
-//The function sample_ticker_block() is called every 50ms, and should run close to the middle of every timeslot
-//There are 10 time slots in each 500ms period
-//Slot 0 is when the beacon is flashing
-//Slot 1 should be IR-free and is used to measure background IR data, stored in background_sensor_data[]
-//Slot 2-8 are for the 7 robots; slot-1 = robot_id
-//In slot 9, the robot processes the data [and doesn't store and new readings]
-//It checks if the beacon is visible, if any robots are, calculates their bearings if they are, and transfers the background and active IR data for the robot
-void sample_ticker_block(){
- //If we are in time-step 0 to 8, store the background data in an array
- if(pulse_step < 9){
- store_background_raw_ir_values ();
- for(int i=0;i<8;i++)ir_sensor_data[pulse_step][i]=get_background_raw_ir_value(i);
- }else{
- //If not, process the data
- for(int i=0;i<9;i++){
- unsigned short sum = get_sum_sample(ir_sensor_data[i]);
- unsigned short highest = get_highest_sample(ir_sensor_data[i]);
- //Check if beacon is visible
- if(i==0){
- if(sum > beacon_threshold){
- beacon_found = 1;
- beacon_heading = get_bearing_from_ir_array (ir_sensor_data[0]);
- }else beacon_found = 0;
- //out("Beacon sum:%d 0:%d 4:%d\n",sum,ir_sensor_data[0][0],ir_sensor_data[0][4]);
- }
- if(i==1){
- for(int j=0;j<8;j++)background_sensor_data[j]=ir_sensor_data[1][j];
- }
- if(i>1){
- char test_robot = i-1;
- if(test_robot == robot_id){
- for(int j=0;j<8;j++)reflected_sensor_data[j]=ir_sensor_data[i][j];
- }else{
- if(sum > low_threshold){
- robots_found[test_robot] = 1;
- //Debug--
- //out("Robot %d: [%d][%d][%d][%d][%d][%d][%d][%d]\n",test_robot,ir_sensor_data[i][0],ir_sensor_data[i][1],ir_sensor_data[i][2],ir_sensor_data[i][3],ir_sensor_data[i][4],ir_sensor_data[i][5],ir_sensor_data[i][6],ir_sensor_data[i][7]);
- robots_heading[test_robot] = get_bearing_from_ir_array (ir_sensor_data[i]);
- robots_distance[test_robot] = highest;
- }else robots_found[test_robot] = 0;
- }
- }
- }
- if(show_ir_debug_info == 1)display_ir_readings();
- }
- //Increment pulse step
- pulse_step++;
- if(pulse_step == 10) pulse_step = 0;
-}
-
-
-//Testing function to print out lines showing what robot can currently see in terms of beacon, other robots and obstacles
-void display_ir_readings()
-{
- out("____________________________________\nInfrared Detection at %d ms\n",beacon_debug_timer.read_ms());
- if(beacon_found==1){
- out("Beacon detected at %d degrees\n",beacon_heading);
- }
- for(int j=1;j<8;j++){
- if(robots_found[j])out("Robot %d detected at %d degrees, %d distance\n",j,robots_heading[j],robots_distance[j]);
- }
- out("Reflected values:");
- for(int i=0;i<8;i++){
- out("[%d,%d]",i,reflected_sensor_data[i]);
- }
- out("\nBackground values:");
- for(int i=0;i<8;i++){
- out("[%d,%d]",i,background_sensor_data[i]);
- }
- out("\n\n");
-}
-
-//Returns a 0 if turn is likely to complete in a single timestep, 1 if it is beyond range for single timestep and 2 if the beacon is not found so bearing unknown
-char turn_to_bearing(int bearing)
-{
- if(beacon_found == 0){
- out("Beacon not found: cannot turn to specific bearing\n");
- return 2;
- }else{
- //First calculate the bearing using the angle of beacon relative to robot
- int current_bearing = 360 - beacon_heading;
- //Now work out turn needed to face intended heading
- int target_turn = (bearing - current_bearing) % 360;
- //Adjust to take 10% off turn, stops overshoot
- target_turn = (target_turn * 9) / 10;
- if(target_turn > 180) target_turn -= 360;
- if(target_turn < -180) target_turn += 360;
- //We can't reliably turn more than 280 degrees per second, so set a limit for the turn to that
- char beyond_limit = 0;
- int turn_limit = BEACON_PERIOD / 358;
- if(target_turn > turn_limit) {target_turn = turn_limit; beyond_limit = 1;};
- if(target_turn < -turn_limit) {target_turn = -turn_limit; beyond_limit = 1;};
- out("Turning %d degrees\n",target_turn);
- time_based_turn_degrees(1, target_turn,1);
- return beyond_limit;
- }
-}
\ No newline at end of file