Classify Candy in Free Fall Using TinyML

1/*
2
3  k-NN color classification
4  -------------------------
5
6  This sketch classifies objects using a color sensor.
7
8  First you 'teach'  the Arduino by putting an example of each object close to the color sensor.
9  After this the Arduino will guess the name of objects it is shown based on how  similar
10  the color is to the examples it has seen.
11
12  This example uses  a simple case of k-Nearest Neighbour (k-NN) algorithm where k=1.
13
14  HARDWARE:  Arduino Nano BLE Sense
15
16  USAGE: Follow prompts in serial console. Move object  close to the board to sample its color, then move it away.
17
18  Works best in  a well lit area with objects of different colors.
19
20  NOTE: Make sure Serial  Monitor's line ending setting is configured for "Newline" or "Both NL & CR".
21
22
23  This example code is in the public domain.
24
25*/
26
27#include <Arduino_KNN.h>
28#include  <Arduino_APDS9960.h>
29
30const int INPUTS = 3; // Classifier input is color sensor  data; red, green and blue levels
31const int CLASSES = 3; // Number of objects  we will classify (e.g. Apple, Banana, Orange)
32const int EXAMPLES_PER_CLASS =  1; // Number of times user needs to show examples for each object
33
34// K=1  means the classifier looks for the single closest color example it's seen previously
35const  int K = 1;
36
37// Create a new KNNClassifier
38KNNClassifier myKNN(INPUTS);
39
40//  Names for each class (object type)
41String label[CLASSES];
42
43// Array to  store data to pass to the KNN library
44float color[INPUTS];
45
46// Threshold  for color brightness
47const float THRESHOLD = 0.98;
48int initialAmbient = 0;
49
50void  setup() {
51
52  Serial.begin(9600);
53  while (!Serial);
54
55  // Pins for  the built-in RGB LEDs on the Arduino Nano 33 BLE Sense
56  pinMode(LEDR, OUTPUT);
57  pinMode(LEDG, OUTPUT);
58  pinMode(LEDB, OUTPUT);
59
60  if (!APDS.begin())  {
61    Serial.println("Failled to initialized APDS!");
62    while (1);
63  }
64
65  initialAmbient = readAmbient();
66
67  Serial.println("Arduino k-NN  color classifier");
68
69  // Ask user for the name of each object
70  for (int  currentClass = 0; currentClass < CLASSES; currentClass++) {
71
72    Serial.println("Enter  an object name:");
73    label[currentClass] = readName();
74
75    // Ask user  to show examples of each object
76    for (int currentExample = 0; currentExample  < EXAMPLES_PER_CLASS; currentExample++) {
77
78      Serial.print("Show me an  example ");
79      Serial.println(label[currentClass]);
80
81      // Wait  for an object then read its color
82      readColor(color);
83
84      // Add  example color to the k-NN model
85      myKNN.addExample(color, currentClass);
86
87    }
88  }
89}
90
91
92void loop() {
93
94  int classification;
95
96  // Wait for the object to move away again
97  while (!APDS.proximityAvailable()  || APDS.readProximity() == 0) {}
98
99  Serial.println("Let me guess your object");
100
101  // Wait for an object then read its color
102  readColor(color);
103
104  // Classify  the object
105  classification = myKNN.classify(color, K);
106
107  // Print the  classification
108  Serial.println(label[classification]);
109  Serial.println();
110
111}
112
113int  readAmbient() {
114  int red, green, blue, ambient;
115  while (!APDS.colorAvailable())  {};
116  APDS.readColor(red, green, blue, ambient);
117  return ambient;
118}
119
120void  readColor(float color[]) {
121  int red, green, blue, ambient = 0, colorTotal =  0;
122
123  // Wait until shadow of object passing
124  while (readAmbient() > initialAmbient  * THRESHOLD) {}
125
126  // Wait until we have a color bright enough
127  while  (ambient < initialAmbient * THRESHOLD) {
128
129    // Sample if color is available  and object is close
130    if (APDS.colorAvailable()) {
131
132      // Read color  and proximity
133      APDS.readColor(red, green, blue, ambient);
134      colorTotal  = (red + green + blue);
135    }
136  }
137
138  // Normalise the color sample data  and put it in the classifier input array
139  color[0] = (float)red / colorTotal;
140  color[1] = (float)green / colorTotal;
141  color[2] = (float)blue / colorTotal;
142
143  // Print the red, green and blue percentage values
144  Serial.print(color[0]);
145  Serial.print(",");
146  Serial.print(color[1]);
147  Serial.print(",");
148  Serial.println(color[2]);
149}
150
151
152// reads a name from the Serial Monitor
153String  readName() {
154  String line;
155
156  while (1) {
157    if (Serial.available())  {
158      char c = Serial.read();
159
160      if (c == '\r') {
161        //  ignore
162        continue;
163      } else if (c == '\n') {
164        break;
165      }
166
167      line += c;
168    }
169  }
170
171  return line;
172}