Infrared Radar with Sharp Distance Sensor

In this small project I show you how to create a radar system using Arduino, Sharp Infrared distance sensors and a micro servo.

Feb 2, 2020

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environmental sensing

tracking

communication

Components and supplies

Infrared Proximity Sensor

SG90 Micro-servo motor

Apps and platforms

Arduino IDE

Project description

Code

Characteristic Measurement

arduino

Simple code to measure characteristic of Sharp distance sensor. Open serial communication to check measured ADC Values.

1void setup()
2{
3  Serial.begin(115200);
4}
5 
6void loop()
7{
8   float adcVal;
9   
10  // Read sharp sensor analog value and use a simple filter   on it
11  adcVal = 0.0f;
12  for (int i = 0; i < 50; i++)
13  {
14    adcVal   += analogRead(PA0);
15    delay(10);
16  }
17  adcVal /= 50.0f;
18 
19  //   Print ADC Value
20  Serial.println(adcVal);
21}

void setup()
{
  Serial.begin(115200);
}
 
void loop()
{
   float adcVal;
   
  // Read sharp sensor analog value and use a simple filter   on it
  adcVal = 0.0f;
  for (int i = 0; i < 50; i++)
  {
    adcVal   += analogRead(PA0);
    delay(10);
  }
  adcVal /= 50.0f;
 
  //   Print ADC Value
  Serial.println(adcVal);
}

Characteristic Measurement

arduino

Simple code to measure characteristic of Sharp distance sensor. Open serial communication to check measured ADC Values.

1void setup()
2{
3  Serial.begin(115200);
4}
5 
6void loop()
7{
8  float adcVal;
9   
10  // Read sharp sensor analog value and use a simple filter  on it
11  adcVal = 0.0f;
12  for (int i = 0; i < 50; i++)
13  {
14    adcVal  += analogRead(PA0);
15    delay(10);
16  }
17  adcVal /= 50.0f;
18 
19  //  Print ADC Value
20  Serial.println(adcVal);
21}

void setup()
{
  Serial.begin(115200);
}
 
void loop()
{
  float adcVal;
   
  // Read sharp sensor analog value and use a simple filter  on it
  adcVal = 0.0f;
  for (int i = 0; i < 50; i++)
  {
    adcVal  += analogRead(PA0);
    delay(10);
  }
  adcVal /= 50.0f;
 
  //  Print ADC Value
  Serial.println(adcVal);
}

Radar

arduino

You can customize some paremeters at the top of the document with macros. Note, that if you change the characteristic of the Sharp distance sensor, you have to modify distAdcMap[] array values!

1#include <Servo.h>
2 
3// ------------------------------------------------------------
4//  User parameters
5// ------------------------------------------------------------
6//  Define pin where Sharp sensor is located.
7#define SHARP_PIN       PA0
8// Define  pin where servo is located.
9#define SERVO_PIN       PA9
10// Define the maximum  distance you want to measure in [cm].
11#define DISTANCE_MAX    150
12// Define  the angle value that servo will step between measurements.
13#define SERVO_STEP      2
14// Define the delay in [ms] between measurements.
15#define MEAS_DELAY_MS   30
16 
17 
18// ------------------------------------------------------------
19//  Message handling
20// ------------------------------------------------------------
21//  Sync value in message header
22#define MSG_SYNC                (0x55AA)
23// Start  of checksum calculation in message header
24#define MSG_CHECKSUM_START      (0x55)
25//  Maximum size of a message
26#define MSG_MAX_SIZE            (64)
27 
28// Header  of message structure
29typedef struct
30{
31    uint16_t sync;
32    uint8_t  checkSum;
33    uint8_t cmd;
34} S_MSG_HEADER;
35 
36// Message: Parameters
37typedef  struct
38{
39    uint16_t distanceMax;
40    uint16_t sampleNum;
41} S_MESSAGE_PARAMETERS;
42  
43// Message: Obstacle
44typedef struct
45{
46    uint16_t angle;
47    uint16_t  distance;
48} S_MESSAGE_OBSTACLE;
49 
50// Message identifiers
51typedef enum
52{
53    eMESSAGE_PARAMETERS,
54    eMESSAGE_OBSTACLE,
55} E_MESSAGE_CMD;
56 
57//  Function to send a message to PC Application
58void sendMessage(uint8_t cmd, void*  data)
59{
60  // Structure for message to send
61  static struct
62  {
63    S_MSG_HEADER  header;
64    uint8_t data[MSG_MAX_SIZE];
65  } sendData;
66  uint8_t msgSize;
67  
68  // Get size of data based on command
69  switch (cmd)
70  {
71    case  eMESSAGE_PARAMETERS:
72      msgSize = sizeof(S_MESSAGE_PARAMETERS);
73      break;
74    case eMESSAGE_OBSTACLE:
75      msgSize = sizeof(S_MESSAGE_OBSTACLE);
76      break;
77  }
78 
79  // Fill header of message
80  sendData.header.cmd = cmd;
81  sendData.header.sync  = MSG_SYNC;
82  sendData.header.checkSum = MSG_CHECKSUM_START;
83   
84  // Fill  data bytes
85  for (uint8_t i = 0; i < msgSize; i++)
86  {
87    sendData.data[i]  = ((uint8_t*)(data))[i];
88    sendData.header.checkSum += sendData.data[i];
89  }
90   
91  // Send composed message to PC
92  Serial.write((uint8_t*)&sendData,  sizeof(S_MSG_HEADER) + msgSize);
93}
94 
95// ------------------------------------------------------------
96//  Distance calculation
97// ------------------------------------------------------------
98//  Structure to store ADC Value - Distance pairs
99typedef struct {
100  float distance;
101  float adcVal;
102} S_DIST_ADC_MAP;
103 
104// TODO
105// ADC Value - Distance  pairs
106// Fill it measured SHARP Sensor characteristic values.
107S_DIST_ADC_MAP  distAdcMap[] = {
108  {12,  3599},
109  {20,  3122},
110  {30,  2295},
111  {40,  1733},
112  {50,  1381},
113  {60,  1191},
114  {70,  1000},
115  {80,  855},
116  {90,  751},
117  {100, 662},
118  {110, 606},
119  {120, 559},
120  {130, 517},
121  {140, 465},
122  {150, 418},
123};
124 
125// Function to get distance [cm] from  measured ADC Value
126float getDistance(float adcVal)
127{
128  float distance =  DISTANCE_MAX;
129 
130  // Linear interpolation from measured ADC value and MAP.
131  for (int i = 1; i < (sizeof(distAdcMap)/sizeof(S_DIST_ADC_MAP)); i++)
132  {
133    if (adcVal > distAdcMap[i].adcVal)
134    {
135      float factor = (adcVal  - distAdcMap[i].adcVal)/(distAdcMap[i-1].adcVal - distAdcMap[i].adcVal);
136      distance  = factor * (distAdcMap[i-1].distance - distAdcMap[i].distance) + distAdcMap[i].distance;
137      break;
138    }
139  }
140 
141  return distance;
142}
143 
144// ------------------------------------------------------------
145//  Application
146// ------------------------------------------------------------
147//  Global variables
148Servo myServo;
149int servoVal = 0;
150int servoDir = SERVO_STEP;
151S_MESSAGE_OBSTACLE  msgObstacle;
152S_MESSAGE_PARAMETERS msgParameters;
153 
154void setup()
155{
156  Serial.begin(115200);
157  myServo.attach(SERVO_PIN);
158  myServo.write(servoVal);
159  
160  msgParameters.distanceMax = DISTANCE_MAX;
161  msgParameters.sampleNum = (180/SERVO_STEP);
162}
163  
164void loop()
165{
166  float adcVal;
167  float distance;
168 
169  // Send parameters  at start
170  if (servoVal == 0)
171    sendMessage(eMESSAGE_PARAMETERS, &msgParameters);
172  
173  // Read sharp sensor analog value and use a simple filter on it.
174  adcVal  = 0.0f;
175  for (int i = 0; i < 10; i++)
176    adcVal += analogRead(SHARP_PIN);
177  adcVal /= 10.0f;
178  distance = getDistance(adcVal);
179 
180  // Compose send  data structure from measured values
181  msgObstacle.angle    = servoVal;
182  msgObstacle.distance  = (uint16_t)distance;
183  sendMessage(eMESSAGE_OBSTACLE, &msgObstacle);
184 
185  // Set servo to next position
186  if (servoVal >= 180)
187    servoDir = -SERVO_STEP;
188  else if (servoVal <= 0)
189    servoDir = +SERVO_STEP;
190     
191  servoVal  += servoDir;
192  myServo.write(servoVal);
193 
194  // Wait until new measurement
195  delay(MEAS_DELAY_MS);
196}

#include <Servo.h>
 
// ------------------------------------------------------------
//  User parameters
// ------------------------------------------------------------
//  Define pin where Sharp sensor is located.
#define SHARP_PIN       PA0
// Define  pin where servo is located.
#define SERVO_PIN       PA9
// Define the maximum  distance you want to measure in [cm].
#define DISTANCE_MAX    150
// Define  the angle value that servo will step between measurements.
#define SERVO_STEP      2
// Define the delay in [ms] between measurements.
#define MEAS_DELAY_MS   30
 
 
// ------------------------------------------------------------
//  Message handling
// ------------------------------------------------------------
//  Sync value in message header
#define MSG_SYNC                (0x55AA)
// Start  of checksum calculation in message header
#define MSG_CHECKSUM_START      (0x55)
//  Maximum size of a message
#define MSG_MAX_SIZE            (64)
 
// Header  of message structure
typedef struct
{
    uint16_t sync;
    uint8_t  checkSum;
    uint8_t cmd;
} S_MSG_HEADER;
 
// Message: Parameters
typedef  struct
{
    uint16_t distanceMax;
    uint16_t sampleNum;
} S_MESSAGE_PARAMETERS;
  
// Message: Obstacle
typedef struct
{
    uint16_t angle;
    uint16_t  distance;
} S_MESSAGE_OBSTACLE;
 
// Message identifiers
typedef enum
{
    eMESSAGE_PARAMETERS,
    eMESSAGE_OBSTACLE,
} E_MESSAGE_CMD;
 
//  Function to send a message to PC Application
void sendMessage(uint8_t cmd, void*  data)
{
  // Structure for message to send
  static struct
  {
    S_MSG_HEADER  header;
    uint8_t data[MSG_MAX_SIZE];
  } sendData;
  uint8_t msgSize;
  
  // Get size of data based on command
  switch (cmd)
  {
    case  eMESSAGE_PARAMETERS:
      msgSize = sizeof(S_MESSAGE_PARAMETERS);
      break;
    case eMESSAGE_OBSTACLE:
      msgSize = sizeof(S_MESSAGE_OBSTACLE);
      break;
  }
 
  // Fill header of message
  sendData.header.cmd = cmd;
  sendData.header.sync  = MSG_SYNC;
  sendData.header.checkSum = MSG_CHECKSUM_START;
   
  // Fill  data bytes
  for (uint8_t i = 0; i < msgSize; i++)
  {
    sendData.data[i]  = ((uint8_t*)(data))[i];
    sendData.header.checkSum += sendData.data[i];
  }
   
  // Send composed message to PC
  Serial.write((uint8_t*)&sendData,  sizeof(S_MSG_HEADER) + msgSize);
}
 
// ------------------------------------------------------------
//  Distance calculation
// ------------------------------------------------------------
//  Structure to store ADC Value - Distance pairs
typedef struct {
  float distance;
  float adcVal;
} S_DIST_ADC_MAP;
 
// TODO
// ADC Value - Distance  pairs
// Fill it measured SHARP Sensor characteristic values.
S_DIST_ADC_MAP  distAdcMap[] = {
  {12,  3599},
  {20,  3122},
  {30,  2295},
  {40,  1733},
  {50,  1381},
  {60,  1191},
  {70,  1000},
  {80,  855},
  {90,  751},
  {100, 662},
  {110, 606},
  {120, 559},
  {130, 517},
  {140, 465},
  {150, 418},
};
 
// Function to get distance [cm] from  measured ADC Value
float getDistance(float adcVal)
{
  float distance =  DISTANCE_MAX;
 
  // Linear interpolation from measured ADC value and MAP.
  for (int i = 1; i < (sizeof(distAdcMap)/sizeof(S_DIST_ADC_MAP)); i++)
  {
    if (adcVal > distAdcMap[i].adcVal)
    {
      float factor = (adcVal  - distAdcMap[i].adcVal)/(distAdcMap[i-1].adcVal - distAdcMap[i].adcVal);
      distance  = factor * (distAdcMap[i-1].distance - distAdcMap[i].distance) + distAdcMap[i].distance;
      break;
    }
  }
 
  return distance;
}
 
// ------------------------------------------------------------
//  Application
// ------------------------------------------------------------
//  Global variables
Servo myServo;
int servoVal = 0;
int servoDir = SERVO_STEP;
S_MESSAGE_OBSTACLE  msgObstacle;
S_MESSAGE_PARAMETERS msgParameters;
 
void setup()
{
  Serial.begin(115200);
  myServo.attach(SERVO_PIN);
  myServo.write(servoVal);
  
  msgParameters.distanceMax = DISTANCE_MAX;
  msgParameters.sampleNum = (180/SERVO_STEP);
}
  
void loop()
{
  float adcVal;
  float distance;
 
  // Send parameters  at start
  if (servoVal == 0)
    sendMessage(eMESSAGE_PARAMETERS, &msgParameters);
  
  // Read sharp sensor analog value and use a simple filter on it.
  adcVal  = 0.0f;
  for (int i = 0; i < 10; i++)
    adcVal += analogRead(SHARP_PIN);
  adcVal /= 10.0f;
  distance = getDistance(adcVal);
 
  // Compose send  data structure from measured values
  msgObstacle.angle    = servoVal;
  msgObstacle.distance  = (uint16_t)distance;
  sendMessage(eMESSAGE_OBSTACLE, &msgObstacle);
 
  // Set servo to next position
  if (servoVal >= 180)
    servoDir = -SERVO_STEP;
  else if (servoVal <= 0)
    servoDir = +SERVO_STEP;
     
  servoVal  += servoDir;
  myServo.write(servoVal);
 
  // Wait until new measurement
  delay(MEAS_DELAY_MS);
}

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tothmiki91

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Intro

Components and supplies

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Project description

Code