Why Hybrid
Circuit Schematic/ Diagram
CAD Model
My Old Delta Robot
Use Of Colored Balls
Arduino IoT Cloud
Total Operational Area Of the Robot (Workspace
Controlling With Custom Build Web Server
Drawing Pre-Programmed Coded Shapes
Future Applications

Published April 8, 2025 © GPL3+

DIY Hybrid Delta Robot | Servo | Inverse Kinematics | SG-90

I built a cloud-controlled delta robot to draw coded shapes, Hoping to propose to my girlfriend with a perfect heart.

IntermediateFull instructions provided174

Things used in this project

Hardware components

Arduino UNO

SG90 Micro-servo motor

9V 1A Switching Wall Power Supply

Breadboard (generic)

Jumper wires (generic)

Software apps and online services

Arduino IDE

Arduino IoT Cloud

Python IDE

Hand tools and fabrication machines

Scissor, Electrician

Wire Cutter / Stripper, 5.25 " Overall Length

Breadboard, 830 Tie Points

Premium Female/Male Extension Jumper Wires, 40 x 6" (150mm)

Story

Full video Demonstration

I built a cloud-controlled delta robot to draw coded shapes. Since my drawing skills are poor, I used servo motors, an Arduino Uno, and computer vision to track the robot’s movements.

Why Hybrid?

Because it uses solid links as well as flexible cables.

Circuit Schematic/ Diagram

Circuit Schematic Of the hybrid delta robot

The circuit of this robot has a left servo motor, a right servo motor, the ground, power and the data or PWM signal wires. All of them connect to the microcontroller on the Arduino Uno prototyping board.

CAD Model

CAD design of the hybrid delta robot with two servo motors

I have added two servo motors, attached two solid links and a cable or thread betwen the links. Both servo motors are controlled by the Arduino Uno R3 prototyping board.

My Old Delta Robot

Delta robot with all solid links

I have previously built a delta robot with all solid links, and that was horizontal, but this one is vertical and has flexible cables.

Use Of Colored Balls

1 / 3 • Working Prototype of the delta robot with coloured balls for tracking

These balls are attached at the joints of this robot, this helps our computer vision software to easily distinguish and track each joint. The computer vision detects and draws a boundry box around the object detected. This helps in recognizing the movement of the end effector of the robot, and to delect the shape drawn by our robot. The computer vision can later be used to manipulate the robot as well.

Arduino IoT Cloud

dashboard on arduino cloud

I also integrated IoT control, allowing me to move the robot remotely using sliders on an Arduino Cloud dashboard. I have created a dashboard on arduino cloud. there I have created two sliders for each motor. By changing the value on the slider, the respective motor moves.the slider is directly proportional to the motor. I can control this robot from anywhere.

Total Operational Area Of the Robot (Workspace)

Simulated Workspace Of the Robot

This is not a robot-arm kind of robot, so it has a limited area of operation or workspace. The workspace refers to the total area within which the robot's end-effector can operate or reach. We have two motors here; if any of them or both of them reach their extreme points, then it will be the limit of our robot. So we have to work within the limits of these points.

Real Workspace Of the Delta Robot

This green colored line is our robot's workspace. Within this area, we can draw anything and reach any point; it all boils down to our software capability. The robot's workspace was mapped out, and I used inverse kinematics to convert shape coordinates into motor angles.

Controlling With Custom Build Web Server

Concept of controlling it via webpage

I developed a web interface where users could draw a shape on a phone, which was then replicated by the robot in real life.

drawing some random shape one custom web page

I have a mobile phone, on which I'll open the webpage. I'll draw the shape. The coordinates of the shape will be sent to the computer, which has a python web server running on it. The web server will then send the commands to the Arduino Uno prototyping board serially. The microcontroller will calculate the proper angles of the servos and send them to the servos. Servos will move and draw the same shape.

Drawing Pre-Programmed Coded Shapes

Drawing Triangle With Code

I have written code that generated the coordinates for these shapes.

Drawing Circle With Code

These coordinates are then converted to the angles for both of the servo motors.

Drawing Heart With Code

This process is also called inverse kinematics.

Future Applications

1 / 2

By adding a third motor, it can be transformed into a 3D delta robot capable of industrial applications like pick-and-place tasks and 3D printing.

Full Video Demonstration Of the Hybrid Delta Robot

Robotics EveryDay!

Custom parts and enclosures

Sketchfab still processing.

Schematics

Code

Full code to control the hybrid delta robot

#include <Servo.h>

Servo m1,m2;    
int i,j;
float l1=3.1,l2=7.2; //l = 6 cm length of link 
float x,y;
float d, d1, d2, h;
float ox1=0, oy1=0;
float ox2=ox1+7, oy2=0;
int dly = 10;

void setup() {
  m1.attach(5);  //left
  m2.attach(6);  //right
  Serial.begin(9600);
  m1.write(90);
  m2.write(90);

}

float angle(float x, float y, float ox, float oy){
  
  d= sqrt(((x-ox)*(x-ox))+((y-oy)*(y-oy)));

  d1=(l1*l1 - (l2*l2)+d*d)/(2*d);

  h = sqrt(l1*l1 - d1*d1);

  float phi=atan2(h,d1); 
  return phi;
  
}

float left_servo_angle(float x, float y){

  float theta= atan2(y-oy1,x-ox1); // phi 2, angle between d and l 

  float phi1 = angle(x, y, ox1, oy1);
  
  float phi = (theta + phi1)*180/PI;

  
  return phi;
}

float right_servo_angle(float x, float y){

  float theta= atan2(y-oy2,x-ox2); // phi 2, angle between d and l 

  float phi1 = angle(x, y, ox2, oy2);
  
  float phi = (theta - phi1)*180/PI;
  return phi;
  
}

void move(float x, float y){
  float phi1 = left_servo_angle(x,y);
  float phi2 = right_servo_angle(x,y);

  if (((phi1>10) && (phi1<170)) && ((phi2>10) && (phi2<170))){
    m1.writeMicroseconds((int)((phi1/180)*1500+700));
    m2.writeMicroseconds((int)((phi2/180)*1500+700));
    delay(dly);  
  }
}

void line(){
  float x = ox2/2;
  float y;
  float steps=0.01;
  
  for(y=0;y<12;y+=steps){
    move(x,y);
  }

  for(y;y>0;y-=steps){
    move(x,y);
  }

}

void loop() {
  line();
}

DIY Hybrid Delta Robot | Servo | Inverse Kinematics | SG-90