Psi Swarm Code V0.41 [With Beautiful Meme program]
Dependencies: PsiSwarmLibrary mbed
Fork of BeautifulMemeProjectBT by
Diff: BeautifulMeme/beacon.cpp
- Revision:
- 30:513457c1ad12
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/BeautifulMeme/beacon.cpp Tue Mar 15 00:58:43 2016 +0000 @@ -0,0 +1,376 @@ +/// PsiSwarm Beautiful Meme Project Source Code +/// Version 0.41 +/// 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 "bmeme.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