Ultrasonic occupancy counter

1/*
2   This project was developed by the Design and Manufacturing Futures  Lab at the University of Bristol as part of Project Clean Access
3   More information  about the lab and the project can be found here: https://dmf-lab.co.uk/project-clean-access/
4   This code is for a counter to be placed in a shop entrance with separate entry  and exit channels
5   There are detailed instructions for this project on the  Instructables website:
6
7   The hardware required for this product:
8   2  x HC-SR04 Ultrasonic sensor
9   2 x 560 Ohm resistor
10   1 x Red LED
11   1  x Green LED
12   1 x Arduino Uno
13   Power supply
14   Correct USB cable for  uploading sketch to Arduino board
15
16   Credit goes to Tim Eckel for developing  the NewPing library and example sketches.
17*/
18
19#include <NewPing.h>
20//Defining  where the components are attached
21#define TRIG_IN A1
22#define TRIG_OUT 3
23#define  ECHO_IN A2
24#define ECHO_OUT 4
25#define LED_WAIT 12
26#define LED_ENTER 9
27
28#define  iterations 5 //Number of readings in the calibration stage
29#define MAX_DISTANCE  150 // Maximum distance (in cm) for the sensors to try to read.
30#define DEFAULT_DISTANCE  45 // Default distance (in cm) is only used if calibration fails.
31#define MIN_DISTANCE  15 // Minimum distance (in cm) for calibrated threshold.
32
33float calibrate_in  = 0, calibrate_out = 0; // The calibration in the setup() function will set these  to appropriate values.
34float distance_in, distance_out; // These are the distances  (in cm) that each of the Ultrasonic sensors read.
35int count = 0, limit = 5; //Occupancy  limit should be set here: e.g. for maximum 8 people in the shop set 'limit = 8'.
36bool  prev_inblocked = false, prev_outblocked = false; //These booleans record whether  the entry/exit was blocked on the previous reading of the sensor.
37
38NewPing  sonar[2] = {   // Sensor object array.
39  NewPing(TRIG_IN, ECHO_IN, MAX_DISTANCE),  // Each sensor's trigger pin, echo pin, and max distance to ping.
40  NewPing(TRIG_OUT,  ECHO_OUT, MAX_DISTANCE)
41};
42
43/*
44   A quick note that the sonar.ping_cm()  function returns 0 (cm) if the object is out of range / nothing is detected.
45   We will include a test to remove these erroneous zero readings later.
46*/
47
48void  setup() {
49  Serial.begin(115200); // Open serial monitor at 115200 baud to see  ping results.
50  pinMode(2, OUTPUT); pinMode(5, OUTPUT); pinMode(A0, OUTPUT);  pinMode(A3, OUTPUT); pinMode(11, OUTPUT);
51  digitalWrite(2, HIGH); digitalWrite(5,  LOW); digitalWrite(A0, HIGH); digitalWrite(A3, LOW); digitalWrite(11, LOW);
52  pinMode(LED_WAIT, OUTPUT), pinMode(LED_ENTER, OUTPUT);
53  digitalWrite(LED_WAIT,  HIGH); digitalWrite(LED_ENTER, HIGH); //Both LEDs are lit to alert user to ongoing  calibration.
54  Serial.println("Calibrating...");
55  delay(1500);
56  for  (int a = 0; a < iterations; a++) {
57    delay(50);
58    calibrate_in += sonar[0].ping_cm();
59    delay(50);
60    calibrate_out += sonar[1].ping_cm();
61    delay(200);
62  }
63  calibrate_in = 0.75 * calibrate_in / iterations; //The threshold is set  at 75% of the average of these readings. This should prevent the system counting  people if it is knocked.
64  calibrate_out = 0.75 * calibrate_out / iterations;
65
66  if (calibrate_in > MAX_DISTANCE || calibrate_in < MIN_DISTANCE) { //If the calibration  gave a reading outside of sensible bounds, then the default is used
67    calibrate_in  = DEFAULT_DISTANCE;
68  }
69  if (calibrate_out > MAX_DISTANCE || calibrate_out  < MIN_DISTANCE) {
70    calibrate_out = DEFAULT_DISTANCE;
71  }
72
73  Serial.print("Entry  threshold set to: ");
74  Serial.println(calibrate_in);
75  Serial.print("Exit  threshold set to: ");
76  Serial.println(calibrate_out);
77  digitalWrite(LED_WAIT,  LOW); digitalWrite(LED_ENTER, LOW); //Both LEDs are off to alert user that calibration  has finished.
78  delay(1000);
79}
80
81void loop() {
82  //  Serial.print("Count:  ");
83  //  Serial.println(count);
84  distance_in = sonar[0].ping_cm();
85  delay(40); // Wait 40 milliseconds between pings. 29ms should be the shortest  delay between pings.
86  distance_out = sonar[1].ping_cm();
87  delay(40);
88  if (distance_in < calibrate_in && distance_in > 0) { // If closer than wall/calibrated  object (person is present) && throw out zero readings
89    if (prev_inblocked  == false) {
90      count++; // Increase count by one
91      Serial.print("Count:  ");
92      Serial.println(count);
93    }
94    prev_inblocked = true;
95  } else {
96    prev_inblocked = false;
97  }
98  if (distance_out < calibrate_out  && distance_out > 0) {
99    if (prev_outblocked == false) {
100      count--;  // Decrease count by one
101      Serial.print("Count: ");
102      Serial.println(count);
103    }
104    prev_outblocked = true;
105  } else {
106    prev_outblocked = false;
107  }
108//    //If there are fewer people in the shop than the limit, light is green,  else it is red
109  if (count < limit) {
110    digitalWrite(LED_WAIT, LOW);
111    digitalWrite(LED_ENTER, HIGH);
112  } else {
113    digitalWrite(LED_WAIT, HIGH);
114    digitalWrite(LED_ENTER, LOW);
115  }
116}

1/*
2   This project was developed by the Design and Manufacturing Futures   Lab at the University of Bristol as part of Project Clean Access
3   More information   about the lab and the project can be found here: https://dmf-lab.co.uk/project-clean-access/
4    This code is for a counter to be placed in a shop entrance with separate entry   and exit channels
5   There are detailed instructions for this project on the   Instructables website:
6
7   The hardware required for this product:
8   2   x HC-SR04 Ultrasonic sensor
9   2 x 560 Ohm resistor
10   1 x Red LED
11   1   x Green LED
12   1 x Arduino Uno
13   Power supply
14   Correct USB cable for   uploading sketch to Arduino board
15
16   Credit goes to Tim Eckel for developing   the NewPing library and example sketches.
17*/
18
19#include <NewPing.h>
20//Defining   where the components are attached
21#define TRIG_IN A1
22#define TRIG_OUT 3
23#define   ECHO_IN A2
24#define ECHO_OUT 4
25#define LED_WAIT 12
26#define LED_ENTER 9
27
28#define   iterations 5 //Number of readings in the calibration stage
29#define MAX_DISTANCE   150 // Maximum distance (in cm) for the sensors to try to read.
30#define DEFAULT_DISTANCE   45 // Default distance (in cm) is only used if calibration fails.
31#define MIN_DISTANCE   15 // Minimum distance (in cm) for calibrated threshold.
32
33float calibrate_in   = 0, calibrate_out = 0; // The calibration in the setup() function will set these   to appropriate values.
34float distance_in, distance_out; // These are the distances   (in cm) that each of the Ultrasonic sensors read.
35int count = 0, limit = 5; //Occupancy   limit should be set here: e.g. for maximum 8 people in the shop set 'limit = 8'.
36bool   prev_inblocked = false, prev_outblocked = false; //These booleans record whether   the entry/exit was blocked on the previous reading of the sensor.
37
38NewPing   sonar[2] = {   // Sensor object array.
39  NewPing(TRIG_IN, ECHO_IN, MAX_DISTANCE),   // Each sensor's trigger pin, echo pin, and max distance to ping.
40  NewPing(TRIG_OUT,   ECHO_OUT, MAX_DISTANCE)
41};
42
43/*
44   A quick note that the sonar.ping_cm()   function returns 0 (cm) if the object is out of range / nothing is detected.
45    We will include a test to remove these erroneous zero readings later.
46*/
47
48void   setup() {
49  Serial.begin(115200); // Open serial monitor at 115200 baud to see   ping results.
50  pinMode(2, OUTPUT); pinMode(5, OUTPUT); pinMode(A0, OUTPUT);   pinMode(A3, OUTPUT); pinMode(11, OUTPUT);
51  digitalWrite(2, HIGH); digitalWrite(5,   LOW); digitalWrite(A0, HIGH); digitalWrite(A3, LOW); digitalWrite(11, LOW);
52   pinMode(LED_WAIT, OUTPUT), pinMode(LED_ENTER, OUTPUT);
53  digitalWrite(LED_WAIT,   HIGH); digitalWrite(LED_ENTER, HIGH); //Both LEDs are lit to alert user to ongoing   calibration.
54  Serial.println("Calibrating...");
55  delay(1500);
56  for   (int a = 0; a < iterations; a++) {
57    delay(50);
58    calibrate_in += sonar[0].ping_cm();
59     delay(50);
60    calibrate_out += sonar[1].ping_cm();
61    delay(200);
62   }
63  calibrate_in = 0.75 * calibrate_in / iterations; //The threshold is set   at 75% of the average of these readings. This should prevent the system counting   people if it is knocked.
64  calibrate_out = 0.75 * calibrate_out / iterations;
65
66   if (calibrate_in > MAX_DISTANCE || calibrate_in < MIN_DISTANCE) { //If the calibration   gave a reading outside of sensible bounds, then the default is used
67    calibrate_in   = DEFAULT_DISTANCE;
68  }
69  if (calibrate_out > MAX_DISTANCE || calibrate_out   < MIN_DISTANCE) {
70    calibrate_out = DEFAULT_DISTANCE;
71  }
72
73  Serial.print("Entry   threshold set to: ");
74  Serial.println(calibrate_in);
75  Serial.print("Exit   threshold set to: ");
76  Serial.println(calibrate_out);
77  digitalWrite(LED_WAIT,   LOW); digitalWrite(LED_ENTER, LOW); //Both LEDs are off to alert user that calibration   has finished.
78  delay(1000);
79}
80
81void loop() {
82  //  Serial.print("Count:   ");
83  //  Serial.println(count);
84  distance_in = sonar[0].ping_cm();
85   delay(40); // Wait 40 milliseconds between pings. 29ms should be the shortest   delay between pings.
86  distance_out = sonar[1].ping_cm();
87  delay(40);
88   if (distance_in < calibrate_in && distance_in > 0) { // If closer than wall/calibrated   object (person is present) && throw out zero readings
89    if (prev_inblocked   == false) {
90      count++; // Increase count by one
91      Serial.print("Count:   ");
92      Serial.println(count);
93    }
94    prev_inblocked = true;
95   } else {
96    prev_inblocked = false;
97  }
98  if (distance_out < calibrate_out   && distance_out > 0) {
99    if (prev_outblocked == false) {
100      count--;   // Decrease count by one
101      Serial.print("Count: ");
102      Serial.println(count);
103     }
104    prev_outblocked = true;
105  } else {
106    prev_outblocked = false;
107   }
108//    //If there are fewer people in the shop than the limit, light is green,   else it is red
109  if (count < limit) {
110    digitalWrite(LED_WAIT, LOW);
111     digitalWrite(LED_ENTER, HIGH);
112  } else {
113    digitalWrite(LED_WAIT, HIGH);
114     digitalWrite(LED_ENTER, LOW);
115  }
116}