UV disinfection robot

Concept

In this amid pandemic the disinfection is very essential to prevent spreading viruses. It affected every walks of our life directly or indirectly. The disinfection is very difficult in crowded areas like hospital, shopping areas etc. So the low cost and sustainable solution is more acceptable in this case.

The disease is transmitted by Bio-organisms such as bacteria and viruses. Its well known fact that such organisms become inactive when exposed to Ultraviolet rays. Especially amid this pandemic, UV-C rays are very effective way to eradicate those destructive bio-organisms. But its also very dangerous falling these rays on the human body.

That is why robots are relevant in such situations. Robots are in use for a number of applications where humans can be at risk of exposure. Robots are able to perform daily tasks with great precision, clarity and consistency with very little or without human assistance.

Here we are creating the Robot called UV disinfection robot . This remotely controlled robot also contains extra safety features like collision avoidance and human exposure. This robot is 1.5 meter long.

UV disinfection robot

Here our design.

Here some photos about the robot.

Human detection(pir sensor)

Collision avoidance(ultrasonic sensor) and camera

Here our remote controlled disinfecting robot at work. It automatically turns off the UV-lamp when detect human exposure.UV lamp can be controlled by manually.

It should be turned on when it reaches the disinfection site. If human presence is detected during operation, it will be turned off by itself. It must be turned on manually to work again. When the robot starts to move, it will detect obstacle up to 30cm in front and stop there and sound the alarm. If we see an obstacle in front of it and try to move it forward, it will come to a standstill.

Here the views of camera

Step 1: Building the UV Robot

• Step 1.1: Motorand frame

We used the 4 Geared DC 12v motor 100rpm, It has high torque. The motor mounted on the plywood. The motor well mounted with clamps and screws

The plywood is hard and good base material to this robot. Its dimension is 30cmx45cm. The front part is shaped as half hexagon and its two side is 12cm and front is 9cm.

Firstly mounted two motors only, another motor is placed after the completion of UV-lamp stand.

Then cut the thermocol to correct dimension as described above, the image shown below is the front part of the robot.

Then the cut pieces placed on the plywood.

• Step 1.2: UV-lamp installation

UV-lamp stand is made up of PVC pipe its 1.5m long and 50mm diameter.

The bottom of the pipe a small plywood piece is screwed.

We are using 4 UV tubes, when the robot moves we need to spread the UV light on a wider area to disinfect and also the floor. So we can use the aluminium foil to spread light and placed the 4 UV tube surrounding of the pvc pipe.

Then we have to laminate the PVC pipe with aluminium foil. So the UV light is reflect and we can disinfect a wide area.

UV tube needs the lamp holder to fix surrounding of the pvc pipe. We need a light weight holder.So it created with thermocol and thick paper sheet. For placing the tube surrounding of the pvc pipe we need to cut thermocol in a circular shape.

The center part of the holder is thermocol and the other two side is the thick paper sheet and it also laminated with the aluminium foil.

For disinfecting the floor, we need to make a reflector on the top of the robot.So we made a umbrella shaped reflector.

• Step 1.3: Safety features

Then we need to access a safety feature that is Human detection, it interrupts the UV-light when the living being's movement is detected and prevent from dangerous UV rays.

Human Exposure

We added two PIR sensors to this safety feature. This sensor has 360 degree coverage with 7 meter distance. Its mounted on the front side and back side.

The small boxes are the UV tube driver. Its works on 230v.

Robot Collision

We added two Ultrasonic sensors for this feature one mounted on back side and other one is front. It detects when robot face an obstacle of 30cm away then stop and alert.

• Step 1.4 : Electronics

We need to supply 230v to the UV lamp, we used an 150w inverter

Step 2: Coding

You have to use Raspberry pi to control this robot. This project is made with Raspberry pi 4.Its connected with internet and control through the internet, you can monitor the camera views when the robot moves and you can also control UV lamp.

When robot moves and manually turn on UV lamp, while any movement is detected suddenly it detect and automatically turn off the UV lamp and alert.When the robot starts to move, it will detect obstacle up to 30cm in front and stop there and sound the alarm.

Here we used the keyboard to control the robot, when press arrow keys it will move accordingly and control the UV light when press 'Q' and 'W' - ON and OFF. You can also change the keys by changing the coding.

• Step 2.1: Setup Raspberry pi

First you need to install latest version Raspbian. I recommend to download the latest version with desktop and recommended software from raspberry pi.

You have to download the software and mount it into an SD card with a pi imager software. Then you connect display, Keyboard, mouse and boot it up

After installing the OS, simpler to access VNC, CAMERA.

For enabling VNC and Camera follow these steps,

Select Menu > Preferences > Raspberry Pi Configuration > Interfaces and Ensure VNC is Enabled and also Camera

The camera preview doesn't show just by enabling VNC, you'll go to VNC settings

Click on VNC icon > Menu > Options > Troubleshooting > Enable direct capture mode and Apply the settings

• Step 2.2: Installing the library

The libraries are imported to add the special functions to this code.

To install the libraries open the terminal

First we need pygame library to get keys to control the robot

sudo apt-get install python-pygame

for importing the library

import pygame

The another libraries are built in libraries.So we have no need to install.

• Step 2.3: Keypress

The keyboard keys importing to this project for controlling the robot, by using the pygame library. First import the pygame library

import pygame

Initializing a window

pygame.init()
pygame.display.set_mode((100,100))

Creating a function to get key from keyboard

def getKey(keyName):
    ans = False
    for eve in pygame.event.get():pass
    keyInput = pygame.key.get_pressed()
    myKey = getattr(pygame,'K_{}'.format(keyName))
    if keyInput [myKey]:
        ans = True
    pygame.display.update()
    return ans

• Step 2.4: Camera

The camera is enabled before. We have to get preview

from picamera import PiCamera
from time import sleep

def piCam(w=200,h=100,x=0,y=0,fill=True):
    camera = PiCamera()
    camera.resolution = (w,h)
    camera.start_preview(fullscreen= fill,window=(x,y,w,h))

• Step 2.4: Motor, pir, ultrasonic sensor and controlling UV light

The motor driver, ultrasonic sensor, pir sensor and relay terminals are connected to the raspberry pi GPIO pins

The motor driver have 6 pins three pins to motor 1 and three pins to motor 2.Two enable pin or PWM pin and another pins are direction control pin for each two motor.

For forward direction

GPIO.output(In1A,GPIO.HIGH) # motor1 forward
GPIO.output(In2A,GPIO.LOW)
GPIO.output(In1B,GPIO.HIGH) # motor2 forward
GPIO.output(In2B,GPIO.LOW)

For backward direction

GPIO.output(In1A,GPIO.LOW) # motor2 backward
GPIO.output(In2A,GPIO.HIGH)
GPIO.output(In1B,GPIO.LOW) # motor2 backward
GPIO.output(In2B,GPIO.HIGH)

Setting PWM

pwmA = GPIO.PWM(EnaA,100)
        pwmA.start(0)
 pwmB = GPIO.PWM(EnaB,100)
        pwmB.start(0)

For turning the robot change the dutycycle and we can turn the robot.

PIR sensor is added to detect human exposure. Here the code

if GPIO.input(pir1): # pir1 is defined as pir1 = 18
        print(" Detected ")

The ultrasonic sensor have 2 pin ECHO and TRIGGER(VCC, GND not included)

The basic distance measurement is that measuring the time between triggering and echo. We can use the code to measure the time

GPIO.output(TRIG, True)
  time.sleep(0.00001)
  GPIO.output(TRIG, False)

  while GPIO.input(ECHO)==0:
       GPIO.output(led, False)
  pulse_start = time.time()

  while GPIO.input(ECHO)==1:
      #Check whether the ECHO is HIGH
       GPIO.output(led, False) 
  pulse_end = time.time()
  pulse_duration = pulse_end - pulse_start

  distance = pulse_duration * 17150
  distance = round(distance,2)
  measuredDistance=measuredDistance+distance

For controlling the UV lamp use 2 channel relay.

if getKey('q'): #for on
        GPIO.output(Relay1,GPIO.LOW) # uv light on
elif getKey('w'): #for off
        GPIO.output(Relay1,GPIO.HIGH) #uv light off

Its done. Then run.

Conclusion

This robot can disinfect a wide area with ultraviolet rays.In this situation such robots are very useful to hospital, shopping malls and other people gathering areas.

We now have this robot built in a way that can be controlled remotely, if we use LIDAR we can automatically control this robot from being controlled by remote control and reduce the use of ultrasonic sensors.It will more accurate and efficient. Then we have installed none movable camera instead of a moving one, we can use the servo motor to change none movable as movable camera. We used a small UV tube, if we use a big UV tube the rate of illumination will be increased and it will be more efficient to disinfect a wide area. While using the big UV tube we need to change the inverter.

COVID-19 has terrified billions of people around the world, so we built such a low cost disinfection robot with a sole purpose of taking part in the fight against the pandemic.This robot has infinite future possibilities. We hope you are able to use it in the most effective way.

Thanks for reading!