Object Shooter 1.0

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Kit purchase

Looking for parts? Check out our all-in-one kits below — packed with components, beginner-friendly guides, and tons of fun.

Name	Includes Arduino board	PURCHASE LINK
Ultimate Sensor Kit	Arduino Uno R4 Minima	BUY
Elite Explorer Kit	Arduino Uno R4 WiFi	BUY
3 in 1 Ultimate Starter Kit	Arduino Uno R4 Minima	BUY
Universal Maker Sensor Kit	×	BUY

Course Introduction

In this lesson, we will learn how to use the Ultrasonic Sensor Module and two Servo Motors with the Arduino Board to create a simple object tracking system.

The radar servo scans a 90° range to detect the nearest object, then the second servo automatically rotates to point toward the detected target. A button is used to trigger a new scan, allowing the system to update and re-aim when needed.

Note

If this is your first time working with an Arduino project, we recommend downloading and reviewing the basic materials first.

Required Components

In this project, we need the following components:

SN	COMPONENT INTRODUCTION	QUANTITY	PURCHASE LINK
1	Arduino UNO R4 Minima	1	BUY
2	USB Type-C cable	1
3	Breadboard	1	BUY
4	Wires	Several	BUY
5	Ultrasonic Sensor Module	1	BUY
6	Digital Servo Motor	2	BUY

Wiring

Common Connections:

Digital Servo Motor 1
- Connect to breadboard’s positive power bus.
- Connect to breadboard’s negative power bus.
- Connect to 9 on the Arduino.
Digital Servo Motor 2
- Connect to breadboard’s positive power bus.
- Connect to breadboard’s negative power bus.
- Connect to 10 on the Arduino.
Ultrasonic Sensor Module
- Trig: Connect to 3 on the Arduino.
- Echo: Connect to 2 on the Arduino.
- GND: Connect to breadboard’s negative power bus.
- VCC: Connect to breadboard’s red power bus.

Writing the Code

Note

You can copy this code into Arduino IDE.
Don’t forget to select the board(Arduino UNO R4) and the correct port before clicking the Upload button.

#include <Servo.h>

// Ultrasonic pins
const int TRIG_PIN = 3;
const int ECHO_PIN = 2;

// Servo pins
const int RADAR_SERVO_PIN = 9;
const int SHOOTER_SERVO_PIN = 10;

// Button pin
const int BUTTON_PIN = 6;

// Servo objects
Servo radarServo;
Servo shooterServo;

// Servo center
const int RADAR_CENTER = 90;
const int SHOOTER_CENTER = 90;

// Scan settings
const int SCAN_START = 45;
const int SCAN_END = 135;
const int SCAN_STEP = 2;

// Geometry
const float BASELINE_CM = 5.0;

// Detection range
const float MIN_DIST = 5.0;
const float MAX_DIST = 80.0;

// Calibration
const int SHOOTER_OFFSET = 6;

// Timing
const int SERVO_DELAY = 40;

// State
bool scanned = false;

// Target
float bestDistance = 999.0;
int bestAngle = RADAR_CENTER;
bool targetFound = false;

// -------------------- Distance --------------------
float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);

  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  long duration = pulseIn(ECHO_PIN, HIGH, 18000);

  if (duration == 0) return 999.0;

  return duration * 0.0343 / 2.0;
}

// -------------------- Filter --------------------
float getDistanceFiltered() {
  float a = readDistanceCM();
  float b = readDistanceCM();
  float c = readDistanceCM();

  float mid = max(min(a, b), min(max(a, b), c));
  return mid;
}

// -------------------- Scan --------------------
void scanTarget() {
  bestDistance = 999.0;
  bestAngle = RADAR_CENTER;
  targetFound = false;

  for (int angle = SCAN_START; angle <= SCAN_END; angle += SCAN_STEP) {
    radarServo.write(angle);
    delay(SERVO_DELAY);

    float d = getDistanceFiltered();

    if (d > MIN_DIST && d < MAX_DIST) {
      if (d < bestDistance) {
        bestDistance = d;
        bestAngle = angle;
        targetFound = true;
      }
    }
  }

  radarServo.write(RADAR_CENTER);
  delay(200);
}

// -------------------- Aim --------------------
void aimTarget() {
  if (!targetFound) {
    shooterServo.write(SHOOTER_CENTER);
    return;
  }

  float theta = radians(bestAngle - RADAR_CENTER);

  float x = bestDistance * sin(theta);
  float y = bestDistance * cos(theta);

  float dx = x - BASELINE_CM;
  float dy = y;

  float angleOffset = degrees(atan2(dx, dy));

  int finalAngle = SHOOTER_CENTER + angleOffset + SHOOTER_OFFSET;
  finalAngle = constrain(finalAngle, 0, 180);

  shooterServo.write(finalAngle);
}

// -------------------- Setup --------------------
void setup() {
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  pinMode(BUTTON_PIN, INPUT_PULLUP);

  radarServo.attach(RADAR_SERVO_PIN);
  shooterServo.attach(SHOOTER_SERVO_PIN);

  radarServo.write(RADAR_CENTER);
  shooterServo.write(SHOOTER_CENTER);

  delay(1000);
}

// -------------------- Loop --------------------
void loop() {
  // If not scanned yet → scan once
  if (!scanned) {
    scanTarget();
    aimTarget();
    scanned = true;
  }

  // Button pressed → reset scan
  if (digitalRead(BUTTON_PIN) == LOW) {
    delay(200);  // debounce

    scanned = false;
  }
}