DIY Desk Pet Cat Robot | 4 Servo Arduino Project | Cute Lifelike Movements
🐱 Introduction
Ever wished your desk companion could move, react, and show emotions like a real pet? The Desk Pet Cat Robot brings that idea to life.
This project combines Arduino Uno, four SG90 servo motors, and an HC-SR04 ultrasonic sensor to create a mini robotic cat that reacts to your hand — walking forward, wiggling, or twitching based on distance.
It’s not just another servo demo — it’s a fun, animated, lifelike robot that looks alive. Perfect for students, hobbyists, and engineers who want to combine electronics, mechanics, and creativity.
⚙️ How It Works
The robot acts like a small quadruped animal, with four servos controlling its legs.
An ultrasonic sensor mounted in front measures distance to nearby objects (like your hand).
Depending on the distance, the Arduino triggers different “behaviors”:
-
<10 cm → Scared reaction (jumps back)
-
10–20 cm → Playful (walks + wiggles)
-
20–35 cm → Curious or sleepy (slow twitch or lean)
-
No object → Random idle behavior
The result is a robot that appears to have emotions, reacting differently each time you interact with it.
🧩 Components Required
| Component | Quantity | Description |
|---|---|---|
| Arduino Uno (or Nano) | 1 | Main controller |
| SG90 Micro Servos | 4 | For leg movements |
| HC-SR04 Ultrasonic Sensor | 1 | Detects hand distance |
| Jumper Wires | – | For connections |
| Breadboard | 1 | For easy wiring |
| 5V Power Supply | 1 | For servo motors |
| Frame (3D print or cardboard) | 1 | Body structure for the cat |
⚡ Circuit Diagram and Connections
Arduino Pin Connections:
| Component | Arduino Pin |
|---|---|
| Front Left Servo | D3 |
| Front Right Servo | D5 |
| Back Left Servo | D6 |
| Back Right Servo | D9 |
| HC-SR04 Trig | D10 |
| HC-SR04 Echo | D11 |
| Power | Servos → 5V External |
| Ground | Common GND between Arduino, Sensor, and Servos |
Important:
Servos draw more current than Arduino can supply. Use an external 5V 2A source for servos and connect all grounds together.
🧠 Behavior Logic
| Sensor Input | Behavior | Movement |
|---|---|---|
| Distance < 10 cm | Scared | Quick backward movement |
| 10–20 cm | Playful | Walk forward + tail wiggle |
| 20–35 cm | Curious | Lean and twitch |
| >35 cm | Idle | Random motion or stretch |
Each behavior is made up of servo sequences — small, timed angle changes that create smooth, natural motion.
💻 Arduino Code (Full Working)
#include <Servo.h>
Servo frontLeft;
Servo frontRight;
Servo backLeft;
Servo backRight;
#define trigPin 10
#define echoPin 11
long duration;
int distance;
void setup() {
Serial.begin(9600);
frontLeft.attach(3);
frontRight.attach(5);
backLeft.attach(6);
backRight.attach(9);
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);
randomSeed(analogRead(0));
// Neutral starting position
frontLeft.write(90);
frontRight.write(90);
backLeft.write(90);
backRight.write(90);
}
int getDistance() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH, 20000);
if (duration == 0) return 100;
int dist = duration * 0.034 / 2;
return dist;
}
// ====== Movements ======
void walkForward() {
frontLeft.write(60); frontRight.write(120);
backLeft.write(60); backRight.write(120);
delay(250);
frontLeft.write(120); frontRight.write(60);
backLeft.write(120); backRight.write(60);
delay(250);
}
void wiggleDance() {
for(int i=0;i<3;i++){
frontLeft.write(90); frontRight.write(110);
backLeft.write(70); backRight.write(90);
delay(150);
frontLeft.write(110); frontRight.write(70);
backLeft.write(90); backRight.write(110);
delay(150);
}
}
void scaredJump() {
frontLeft.write(70); frontRight.write(70);
backLeft.write(110); backRight.write(110);
delay(200);
frontLeft.write(110); frontRight.write(110);
backLeft.write(70); backRight.write(70);
delay(200);
}
void sleepyTwitch() {
frontLeft.write(85); frontRight.write(95);
delay(300);
frontLeft.write(95); frontRight.write(85);
delay(300);
}
void curiousLean() {
frontLeft.write(80);
frontRight.write(100);
backLeft.write(80);
backRight.write(100);
delay(600);
frontLeft.write(100);
frontRight.write(80);
backLeft.write(100);
backRight.write(80);
delay(600);
}
void happySway() {
for(int i=0;i<2;i++){
frontLeft.write(100); frontRight.write(80);
backLeft.write(100); backRight.write(80);
delay(400);
frontLeft.write(80); frontRight.write(100);
backLeft.write(80); backRight.write(100);
delay(400);
}
}
// ====== Behavior Engine ======
void reactToDistance(int dist){
if(dist<8){
Serial.println("Scared!");
scaredJump();
} else if(dist<15){
Serial.println("Playful");
walkForward();
wiggleDance();
} else if(dist<25){
Serial.println("Curious");
curiousLean();
} else if(dist<35){
Serial.println("Sleepy");
sleepyTwitch();
} else {
Serial.println("Idle");
int mood = random(0,4);
if(mood==0) wiggleDance();
else if(mood==1) sleepyTwitch();
else if(mood==2) curiousLean();
else happySway();
delay(3000);
}
}
void loop() {
int dist = getDistance();
Serial.print("Distance: "); Serial.println(dist);
reactToDistance(dist);
delay(500);
}
🧠 Result and Behavior
Once powered, your robot will:
React to nearby hands with different movements
Randomly “twitch” when idle
Walk forward or lean when curious
Jump back if startled
It feels surprisingly alive for such a simple circuit — perfect for showing off your robotics and programming creativity.
💡 Tips for Best Results
Calibrate servo angles if movement looks jerky
Use a separate 5V 2A power supply for stable motion
Keep servo arms symmetrical for smooth walking
Add felt feet or soft pads for quieter desk movement
🔗 Resources
Full Project Page (Code + Circuit Download):
👉 https://payhip.com/b/4bhe3
🎯 Conclusion
The Desk Pet Cat Robot is a small but powerful project that blends coding, electronics, and design into a fun, lifelike creation.
You can easily add upgrades like LED eyes, Wi-Fi control, or sound detection to take it even further.
Whether you’re an ICT student, robotics hobbyist, or content creator, this project proves one thing:
you can bring personality to code — even in 4 servos.
Would you like me to create the HTML version next (formatted for Blogger with color-coded code box, headings, and embedded image placeholders)?
That will make your post copy-paste ready with professional formatting
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