Low-Cost UVBot Using SLAM to Mitigate the Spread of Noroviruses in Occupational Spaces

Abstract

Noroviruses (NoVs) cause over 90% of non-bacterial gastroenteritis outbreaks in adults and children in developed countries. Therefore, there is a need for approaches to mitigate the transmission of noroviruses in workplaces to reduce their substantial health burden. We developed and validated a low-cost, autonomous robot called the UVBot to disinfect occupational spaces using ultraviolet (UV) lamps. The total cost of the UVBOT is less than USD 1000, which is much lower than existing commercial robots that cost as much as USD 35,000. The user-friendly desktop application allows users to control the robot remotely, check the disinfection map, and add virtual walls to the map. A 2D LiDAR and a simultaneous localization and mapping (SLAM) algorithm was used to generate a map of the space being disinfected. Tulane virus (TV), a human norovirus surrogate, was used to validate the UVBot's effectiveness. TV was deposited on a painted drywall and exposed to UV radiation at different doses. A 3-log (99.9%) reduction of TV infectivity was achieved at a UV dose of 45 mJ/cm². We further calculated the sanitizing speed as 3.5 cm/s and the efficient sanitizing distance reached up to 40 cm from the UV bulb. The design, software, and environment test data are available to the public so that any organization with minimal engineering capabilities can reproduce the UVBot system.

Keywords: SLAM; UV light; autonomous robot; norovirus; robot disinfection.

Figure 1

UVBot overall assembly and dimensions. (1) iCreate2 mobile robot, (2) lamps, (3) lamp holder, and (4) base structure. (D1) to (D4) are laser-cut support structures. All components were either purchased off the shelf (salmon-colored boxes), 3D printed in PLA using FDM printing (blue-colored boxes), or laser-cut (green-colored boxes).

Figure 2

UVBot key mechanical components. (D1) Designed to mount the LiDAR, (D2) serves as support, (D3) used to house electronic components such as power and the ballast, and (D4) serves to mount the Raspberry Pi 3B. (1) is the iRobot Create 2, (2) is the UV lamps, (3) is 3D printed lamp holder, (4) is 3D printed support structure. All components were either purchased off the shelf (salmon-colored boxes), 3D printed in PLA using FDM printing (blue-colored boxes), or laser-cut (green-colored boxes).

Figure 3

UVBot electrical design overview. In orange is the sanitization module containing the UV lamps and the ballast. In blue is the autonomous movement module containing the mobile robot, the LiDAR sensor, and the microcontroller. Both modules are powered by the same power supply.

Figure 4

Diagram of the software architecture.

Figure 5

Virtual wall function.

Figure 6

(a) UV intensity at different distances from the UV lamp and at different locations of the UV lamp. (b) UV spectrum of the studied UV lamp.

Figure 7

(a) Effect of UV dose and distance on the virus inactivation. (b) TV inactivation as a function of the UV dose for distances of 10, 20, 30, and 40 cm. Note that the regression does not include the points for the highest UV dose obtained when the distance was 10 cm. Log reduction of infectivity is log₁₀ (N₀/N), where N₀ is the infectivity of the viral suspension before exposure to UV, and N is the infectivity of this suspension after UV exposure.

Figure 8

(a) TV inactivation as a function of time measured for different distances (10, 20, 30, 40 cm). (b) Linear regression for TV inactivation as a function of time measured for distances of 10, 20, 30, and 40 cm. Log reduction of infectivity is log₁₀ (N0/N), with N0 as the infectivity of the viral suspension before exposure to UV and N as the infectivity of this suspension after UV exposure.

Figure 9

The UVBot effective distance and targeted disinfection area.

Figure 10

Functional prototype of the UVBot.

Figure 11

UVBot disinfection test in a corridor. (1–3) Progression of the UVBot in this environment.

Figure 12

UVBot disinfection test in an office cell using a virtual wall. Top-left: Photo of the office cell; bottom-left: the stored map; top-right and bottom-right: UVBot disinfection map with the virtual wall.