Project tutorial
COVID-19 Simple Friendly Social Distance Robot Watchzi

COVID-19 Simple Friendly Social Distance Robot Watchzi © GPL3+

Watchzi measure the distance between it and the approaching persons, gives warning with light and sound when 1.5 meters is exceeded.

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Components and supplies

Ard nano
Arduino Nano R3
51gzz5eu9pl. sx425
Ultrasonic Sensor - HC-SR04 (Generic)
Seeed Studio Neopixel 1 mtr RGB LED
use only 1 led , their are 60 on it .
AA Batteries
Battery holder 4x AA with red/black wire
E switch eg1218 image 75px
Slide Switch
Active Buzzer 5V (HXD)
3D filament PLA Black
3D filament PLA transparant or natural for had
53m8781 40
Machine Screw, M3
Brass-threaded-inserts-short M3 (head inserts)
11026 02
Jumper wires (generic)

Necessary tools and machines

3D Printer (generic)
Any 3D printer using PLA and STL files
09507 01
Soldering iron (generic)
Solder some parts , see manual
Solder Wire, Lead Free
26w6260 40
Multitool, Screwdriver
Use to close the back of Watchzi
Wire Stripper & Cutter, 18-10 AWG / 0.75-4mm² Capacity Wires

Apps and online services

Ide web
Arduino IDE
Autodesk fusion 360 logo 4szx21llea
Autodesk Fusion 360
Its only for changing 3D files but not required

About this project

In this time with COVID-19 you see many people standing far too close to a desk, cash register or otherwise. People are not fully aware of the distance of 1, 5 meters (6 feet), for example.

I came up with the idea to make a friendly battery powered robot that can easily stand on a table desk or otherwise.

This robot measures the distance between it and the approaching person and gives a notification. The robot indicates a programmable tone and its hat lights up red. If you come at a safe distance again, the hat will turn green again.

At number 1 you can see how the compleet Watchzi must look like and how its working with 1, 5 mtr distance, futher in this document there is a video.

You can see the 3D printer drawing with his parts.

You can find the 3D STL files futher in this document, I choose for Black PLA and Natural (Had part) for the parts but you can make it in any color you like.

Components I used for Watchzi to compleet it. See list for how many you need

First print the 4 parts in the same color of whatever color you like, I used PLA. See settings in picture 5.

After print the first 4 parts, print the last had part in PLA transparant or natural. The NEOpixel has to shine through the had part because you want to see the red or green color.

Assembly after printing see pictures 7-11

Put the Heat inserts nuts M3 gently in the holes with the Solderpoint and hold them right up. Glue the Batteryholder with 3M tape or glue to the plate and turn it. The hole is for the black and red wire.

Cut 1 NEOPixel (see cutting lines) and stick it to the base, look for the right position of the Din en Dout. Dont glue the had before testing !!

Put the SR04 sensor into the holes and use a bit hot glue to stay in place. After that put the Arduino nano into the place, it will stuck with his headers. Insert the Heat nuts M3 gentle right up with a solder point in there holes.

Put the Active buzzer into the hole after remove the seal !!. The hole into the enclosure makes it to hear the sound. Insert the slide switch and hot glue into the right position. Insert 2x heat M3 on the buttom of the part, the other two you insert it before (7).

When you're finished putting the components on the right places you can wire them, dont use to long wires because you will not able to assembly watchzi at the end because the wires will stuck.

When your finished wiring you program the file into the Arduino nano and test if the watchzi is working well. You can adjust the settings ( look the comments in the INO file). After testing you use 8 Screws M3x8 to assembly the parts. At last you may glue the had on the right place and you have a nice own made friendly social distance robot watchzi.

You can play with the sound or color, even you can use ever color you like and sound, be creative

Enjoy this project and leave any comment or question

Operational and tested At Firecom BV .NL


Program file Arduino Nano V3 for social distance robot WatchziArduino
Program file Arduino Nano V3 for social distance robot Watchzi for Arduino IDE (INO file).
change the distance and Tone and Led color if you like.
Friendly Watchzi Social distance robot 
Made by Mark Huijbers , Netherlands
Used : Arduino Nano R3 
you can change the Neopixel colors ( see color names online)
you can change the tone frequence 

#include "FastLED.h"
#define NUM_LEDS 1 // How many leds ,program counting from 0
#define DATA_PIN 7 // Pin7 on NANO (data leds)

const int trigPin = 4; //ultransone sensor
const int echoPin = 5; //ultransone sensor
long duration;
int distance;
const int buzzer = 9; // buzzer position

void setup() { 
FastLED.addLeds<WS2812B, DATA_PIN, RGB>(leds, NUM_LEDS); // type leds Neopixel with controller WS2821B
pinMode(trigPin, OUTPUT); 
pinMode(echoPin, INPUT); 
pinMode(buzzer, OUTPUT); 

void loop() { 

digitalWrite(trigPin, LOW);
digitalWrite(trigPin, HIGH);
digitalWrite(trigPin, LOW);

duration = pulseIn(echoPin, HIGH);

distance= duration*0.029/2; // calculate for using meters , 150 is equal to 1,5 mtr / 6 Feet

if (distance <= 150){
  leds[0] = CRGB::Red;;
  tone(buzzer, 1000); // tone frequence 1 Khz , you can change them 
else {
   leds[0] = CRGB::Green;;
delay(500); // delay else the neopixel led and measure are to fast 

Custom parts and enclosures

STL file base
3D file for your printer , only have to slice it with your program like prusaslicer
STL file base Plate
3D file for your printer , only have to slice it with your program like prusaslicer
STL file batterypack holder
3D file for your printer , only have to slice it with your program like prusaslicer
STL file had transparant
3D file for your printer , only have to slice it with your program like prusaslicer
STL file lower base plate
3D file for your printer , only have to slice it with your program like prusaslicer


Frizing diagram PDF
Frizing diagram PDF
Fritzing schematic
Fritzing schematic file


Submitted to Contest

1st Place - Social Distance Enablement & Tracking

Touch Less, Do More


  • 1 project

Additional contributors

  • Idea ,design , programming and 3d print by Mark Huijbers

Published on

August 11, 2020

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