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Maker 101
Published © GPL3+

4-Legged Spider Robot With 3D Printed Parts

In this project, I will show you how to make a simple 4-legged walking spider robot using 3D printed parts.

IntermediateFull instructions provided3 hours398
4-Legged Spider Robot With 3D Printed Parts

Things used in this project

Hardware components

SG90 Micro-servo motor
SG90 Micro-servo motor
×8
Doit ESP32 Devkit V1 development board
×1

Software apps and online services

Arduino IDE
Arduino IDE
MIT App Inventor 2
MIT App Inventor 2

Hand tools and fabrication machines

Soldering iron (generic)
Soldering iron (generic)
Solder Wire, Lead Free
Solder Wire, Lead Free

Story

Read more

Custom parts and enclosures

Plate Base

Sketchfab still processing.

Servo Holder

Sketchfab still processing.

Connector Link

Sketchfab still processing.

Leg (Foot)

Sketchfab still processing.

Plate Top

Sketchfab still processing.

Schematics

Components

Code

Spider_Servo_Initial_Positions.ino

Arduino
#include <ESP32Servo.h>

Servo servo_footA;
Servo servo_armA;
Servo servo_footB;
Servo servo_armB;
Servo servo_footC;
Servo servo_armC;
Servo servo_footD;
Servo servo_armD;

// Connect servos to pins
int srv_footA = 13;
int srv_armA = 12;
int srv_footB = 15;
int srv_armB = 2;
int srv_footC = 26;
int srv_armC = 25;
int srv_footD = 17;
int srv_armD = 5;

void setup() {
  servo_footA.attach(srv_footA);
  servo_armA.attach(srv_armA);
  servo_footB.attach(srv_footB);
  servo_armB.attach(srv_armB);
  servo_footC.attach(srv_footC);
  servo_armC.attach(srv_armC);
  servo_footD.attach(srv_footD);
  servo_armD.attach(srv_armD);

  // Set mounting positions
  setInitialPositions();
}

void loop() {

}

void setInitialPositions() {
  // Leg servos: 60
  servo_footA.write(60);
  servo_footB.write(60);
  servo_footC.write(60);
  servo_footD.write(60);

  // Arm servos: 90
  servo_armA.write(90);
  servo_armB.write(90);
  servo_armC.write(90);
  servo_armD.write(90);
}

Spider_ESP32_BLE_Code.ino

Arduino
#include "BluetoothSerial.h"
#include <ESP32Servo.h>

BluetoothSerial SerialBT;
int BTData;

// Commands sent via the mobile app through Bluetooth
//UP = 50
//DOWN = 51
//WALK = 52
//ROUND = 53
//BLINK = 54
//STALL = 55

Servo servo_footA;
Servo servo_armA;
Servo servo_footB;
Servo servo_armB;
Servo servo_footC;
Servo servo_armC;
Servo servo_footD;
Servo servo_armD;

// Servo motor pins
int srv_footA = 13;
int srv_armA = 12;
int srv_footB = 15;
int srv_armB = 2;
int srv_footC = 26;
int srv_armC = 25;
int srv_footD = 17;
int srv_armD = 5;

// Movement limits and speed settings
int Fdw = 60;   // Foot down limit 
int Fup = 80;   // Foot up limit
int Abw = 70;   // Arm backward limit
int Afw = 110;  // Arm forward limit
int spd = 3;    // Movement speed (~2-5)

int p13 = 23;   // LED pin for status indication

/* Check if Bluetooth configurations are enabled in the SDK */
#if !defined(CONFIG_BT_ENABLED) || !defined(CONFIG_BLUEDROID_ENABLED)
#error Bluetooth is not enabled! Please run make menuconfig to and enable it
#endif

void setup() {
  servo_footA.attach(srv_footA);
  servo_armA.attach(srv_armA);
  servo_footB.attach(srv_footB);
  servo_armB.attach(srv_armB);
  servo_footC.attach(srv_footC);
  servo_armC.attach(srv_armC);
  servo_footD.attach(srv_footD);
  servo_armD.attach(srv_armD);
  pinMode(p13, OUTPUT);
  Serial.begin(115200);
  SerialBT.begin("@maker101io");
  Serial.println("Bluetooth Started! Ready to pair...");
  stall(); // Initialize robot to a stable position
  delay(1000);
}

void loop() {
  if(SerialBT.available()){
    BTData = SerialBT.read(); // Read data from the Bluetooth app
  }
  // Execute commands based on received data
  if (BTData == 53) {
    digitalWrite(p13, HIGH);
    ROUND();
    digitalWrite(p13, LOW);
  } else if (BTData == 52) {
    digitalWrite(p13, HIGH);
    WALK();
    digitalWrite(p13, LOW);
  } else if (BTData == 54) {
    BLINK();
    for (int i = 0; i < 7; i++) { WALK(); }
    stall();
    flat_up();
    delay(1000);
    flat_dw();
    delay(1000);
    for (int i = 0; i < 7; i++) { ROUND(); }
    delay(500);
    stall();
  } else if (BTData == 50) {
    flat_up();
  } else if (BTData == 51) {
    flat_dw();
    flat_up();
  } else if (BTData == 55) {
    stall();
    digitalWrite(p13, LOW);
  }
}

// Grouped movements for walking and rotation
void WALK() {
  go_ahead();
  Afoup();
  armAfw();
  Afodw();
  Cfoup();
  armCbw();
  Cfodw();
  Bfoup();
  armBbw();
  Bfodw();
  Dfoup();
  armDfw();
  Dfodw();
}

void ROUND() {
  armAfw();
  armBfw();
  armCfw();
  armDfw();
  Afoup();
  armAbw();
  Afodw();
  Bfoup();
  armBbw();
  Bfodw();
  Cfoup();
  armCbw();
  Cfodw();
  Dfoup();
  armDbw();
  Dfodw();
}

// Foot movements (up and down)
void Afoup() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = min; i <= max; i++) {
    servo_footA.write(i);
    delay(spd);
  }
}

void Bfoup() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = min; i <= max; i++) {
    servo_footB.write(i);
    delay(spd);
  }
}

void Cfoup() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = min; i <= max; i++) {
    servo_footC.write(i);
    delay(spd);
  }
}

void Dfoup() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = min; i <= max; i++) {
    servo_footD.write(i);
    delay(spd);
  }
}

void Afodw() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = max; i >= min; i--) {
    servo_footA.write(i);
    delay(spd);
  }
}

void Bfodw() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = max; i >= min; i--) {
    servo_footB.write(i);
    delay(spd);
  }
}

void Cfodw() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = max; i >= min; i--) {
    servo_footC.write(i);
    delay(spd);
  }
}

void Dfodw() {
  int max = Fup + 5;
  int min = Fdw + 5;
  for (int i = max; i >= min; i--) {
    servo_footD.write(i);
    delay(spd);
  }
}

// Basic movements

void go_ahead() {
  spd = 3;  // ~ 2-5
  for (int i = Afw; i >= Abw; i--) {
    servo_armA.write(i);
    servo_armD.write(i);
    int y = Abw + Afw - i;
    servo_armC.write(y);
    servo_armB.write(y);
    delay(spd);
  }
}

void flat_up() {
  int max = Fup + 5;
  int min = Fdw + 5;
  servo_footA.write(min);
  servo_footB.write(min);
  servo_footC.write(min);
  servo_footD.write(min);
  delay(500);
  for (int i = min; i <= max + 50; i++) {
    servo_footA.write(i);
    servo_footB.write(i);
    servo_footC.write(i);
    servo_footD.write(i);
    delay(spd);
  }
  delay(500);
}

void flat_dw() {
  int max = Fup + 5;
  int min = Fdw + 5;
  servo_footA.write(max);
  servo_footB.write(max);
  servo_footC.write(max);
  servo_footD.write(max);
  delay(500);
  for (int i = max; i >= min; i--) {
    servo_footA.write(i);
    servo_footB.write(i);
    servo_footC.write(i);
    servo_footD.write(i);
    delay(spd);
  }
  delay(500);
}

// single arm mvt A
void armAfw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = min; i <= max; i++) {
    servo_armA.write(i);
    delay(spd);
  }
}

void armAbw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = max; i >= min; i--) {
    servo_armA.write(i);
    delay(spd);
  }
}

// single arm mvt B
void armBfw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = min; i <= max; i++) {
    servo_armB.write(i);
    delay(spd);
  }
}

void armBbw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = max; i >= min; i--) {
    servo_armB.write(i);
    delay(spd);
  }
}

// single arm mvt C
void armCfw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = min; i <= max; i++) {
    servo_armC.write(i);
    delay(spd);
  }
}

void armCbw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = max; i >= min; i--) {
    servo_armC.write(i);
    delay(spd);
  }
}

// single arm mvt D
void armDfw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = min; i <= max; i++) {
    servo_armD.write(i);
    delay(spd);
  }
}

void armDbw() {
  int min = Abw + 0;
  int max = Afw + 0;
  for (int i = max; i >= min; i--) {
    servo_armD.write(i);
    delay(spd);
  }
}

// Initialize robot to a stable state
void stall() {
  BLINK();
  servo_armA.write(90);
  servo_footA.write(60);
  servo_armB.write(90);
  servo_footB.write(60);
  servo_armC.write(90);
  servo_footC.write(60);
  servo_armD.write(90);
  servo_footD.write(60);
  digitalWrite(p13, HIGH);
}

void BLINK() {
  for (int i = 0; i < 3; i++) {
    digitalWrite(p13, HIGH);
    delay(100);
    digitalWrite(p13, LOW);
    delay(100);
  }
}

Credits

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Related channels and tags
  • 3D Printing
  • 3D Printing
  • MIT App Inventor
  • Robotics
  • Robotics