UV DisBot

Why and what’s the need for UV disinfection?

As COVID-19 has been a major health threat to many people all over the globe, many preventive steps are being taken to prevent the coronavirus from being spread. This virus has been spreading since December 2019 through various means. This virus is proven spread through air, surface, and water and it also stays on different substances for some time.

Disinfection/Sterilization of hands and other surfaces with the use of some disinfectants/sterilizers is the only preventive step for now that can be taken to avoid the presence or spread of COVID-19. This can be done by disinfecting/sterilizing the objects or hands with liquid sterilizers like sanitizers and this task can also be performed by the use of UV-C lamps. Sanitizers reduce bacteria on a surface by at least 99.9%, disinfectants kill a wider range of microorganisms (than sanitizers) and these are regulated by EPA.

Ultra-Violet (UV) light is invisible to the human eye and is divided into UV-A, UV-B, and UV-C. UV-C radiation is a known disinfectant for air, water, and surfaces. UV-C is found within the100-280 nm range. The reason to choose UV-C disinfecting lamps than other methods because they defeat micro-organisms protect against micro-organism growth and their disinfection level depends on the dose of UV-C light intensity. They are also easy to use and cost-effective.

Thus to conclude, UV-C lights/lamps have effective disinfection than other modes of sterilization or disinfection. So a robot with UV-C lights can effectively disinfect the air, surface, and water and this robot have a wide range of applications where it can be used, such as schools, universities, other institutions, hospitals, airports, hotels, residences, offices, conference rooms, bathrooms, and a lot more.

Features of this robot

This UV-C germicidal disinfection robot has the following features that ensure good efficiency, portability, ease-of-use, economical, powerful, safer, and reliable.

• Small in size ( L x B x H – 32.5 cm x 26.0 cm x 118.5 cm (or) 0.325 m x 0.26 m x 1.185 m)

• Semi-Autonomous Robot
• Highly durable chassis - Industrial grade
• Has 12V high torque DC geared motors
• Arduino Mega based robot
• 4 UV lamps of 30W power, UV power of 12W, working voltage 102V and 3ft long
• Control robot using Mobile or Remote Control Transmitter
• The interface in mobile involves an IP based web server that can be used for the locomotion of the robot and has emergency buttons
• UV lights on/off control can be switched on robot or mobile
• Economical. Cost around 1200-1400 USD
• Lamp life counters based on hours and no. of times. The data will be logged on an SD card placed onboard
• Emergency stop button on the robot and virtually on the IP webserver (on any device)
• Led indication when UV lights are ON
• Power supply – 2pcs 12V 7Ah lead-acid battery (connected in parallel)
• Power supplied to lamps from 12V DC – 110V AC Inverter Circuit
• Projected Lamp reliability – 9000 hours
• Robot reliability – as far as maintained well
• UV lights shutdown on Motion detection using 3 PIR sensors
• UV lights shutdown on obstacle detection using 6 ultrasonic sensors to avoid a collision
• Lamps can be easily changed/replaced
• Weight of the robot - 20 kilograms

Robot Design Fabrication

The entire chassis of the robot is custom fabricated with 2mm thick mild steel sheets. The plates for the robot are cut using CNC Laser cutting machine in an Industrial estate where the machines are found. We designed the sheets in 2D along with all the necessary holes and supports for placing the components, sensors, and batteries. The 2D CAD file for laser cutting is attached below. All the necessary parts are designed in that file. The batteries are placed in a chassis which can be placed over the Motor base chassis. The battery chassis is designed in a way that it can be directly placed over the base, just matching the side rigid supports. This ensures high stability for the batteries and the rest of the robot. Above the battery chassis, comes the circular plate where the 4 UV-C lights are fixed over a holder. Hollow bean support is provided between the top and base plate where the UV-C lights are fixed. Above the top plate, a Wi-Fi camera and 3 PIR sensors are placed to ensure safety and for controlling the robot.

The 2D CAD for laser cutting is provided below in the CAD section. Once you get the metal sheet cut into pieces, follow the procedure to weld the plates to get the structure/chassis of the robot. Also, the additional metal parts required for the robot are mentioned below.

The procedure on how to weld the sides and other parts are instructed below:

Robot Assembly

The assembly of the robot structure and the electronic components along with the circuit diagram are given below.

How to Use and How it works

Robot

Fabricate the robot as per the instructions given above. Then assemble the parts and components as instructed. Follow the schematics and proceed with the wirings of the components with the Arduino Mega microcontroller, Inverter circuit, and other essential circuits. Then upload the corresponding programs to the microcontroller and the ESP8266 module ( if your control is going to be with IP ).

Once the UV robot is ready, power on the robot. After the robot is powered ON, the UV robot can be controlled from anywhere till the robot is in range with the controller. The UV lights can be turned on/off from the web portal.

When there is human motion detected, the UV lights will go OFF and the robot will stop. There are also inbuilt 6 Ultrasonic sensors which will avoid the robot from hitting any obstacles even if the person who is controlling is trying to hit anything. The reason that the robot will behave to be autonomous in order to ensure safety, it is called as an semi-autonomous robot. The robot overwrites the commands given by the user when there is something hazardous. Even the UV lights will turn ON/OFF where the threshold intensity is reached. when the intensity or the dose goes high, the lights get turned off. There is an emergency stop button on the robot and virtually on the web portal.

This robot will ensure high safety, high reliability, and will be a powerful germicidal disinfector.

Control Unit

We have designed the robot in such a way that, the same robot can be controlled in two ways, by only changing small things in the circuit. The respective circuit assembly representations, diagrams, schematics, and code are given for both types of control.

Type 1 - IP based Web control using mobile or any other device

The first way is to control the robot using the IP based web server specially designed for this robot, using any web browser on mobile phone or PC. No internet is required to control the robot in this case. The layout is designed with HTML code and is made sure the controls are easy to understand. The robot movement controls can be done with the 4 respective direction buttons available on the website. An emergency stop button and the control button to turn ON/OFF the UV lights are also provided in the same layout. This ensures good safety measures to suddenly stop the robot if anything hazardous is happening. The control layout through the IP server can be achieved by going to the link, http://192.168.4.1 when the robot is in range with the device you are trying to control.

Type 2 - 2.4Ghz RC transmitter Control

The second way is to control the robot using a 2.4 GHz RC transmitter. The range in this case would be around 500m depending upon the transmitter. In this case, the ESP8266 module is removed from the previous circuit and it is replaced with the transmitter-receiver module. The robot is made to move using the Aileron/Throttle in the transmitter. The up and down movements of the throttle correspond to the forward and backward movement of the robot. The left and right control of the Aileron correspond to the left and right turn movements of the robot.

The robot can be operated manually by looking at the camera feed on the display. The respective circuit diagrams, schematics, assembly, and the code are given below.