Abstract
Due to the COVID-19 virus being highly transmittable, frequently cleaning and disinfecting facilities is common guidance in public places. However, the more often the environment is cleaned, the higher the risk of cleaning staff getting infected. Therefore, strong demand for sanitizing areas in automatic modes is undoubtedly expected. In this paper, an autonomous disinfection vehicle with an Ultraviolet-C (UVC) lamp is designed and implemented using an ultra-wideband (UWB) positioning sensor. The UVC dose for 90% inactivation of the reproductive ability of COVID-19 is 41.7 J/m2, which a 40 W UVC lamp can achieve within a 1.6 m distance for an exposure time of 30 s. With this UVC lamp, the disinfection vehicle can effectively sterilize in various scenarios. In addition, the high-accuracy UWB positioning system, with the time difference of arrival (TDOA) algorithm, is also studied for autonomous vehicle navigation in indoor environments. The number of UWB tags that use a synchronization protocol between UWB anchors can be unlimited. Moreover, this proposed Gradient Descent (GD), which uses Taylor method, is a high-efficient algorithm for finding the optimal position for real-time computation due to its low error and short calculating time. The generalized traversal path planning procedure, with the edge searching method, is presented to improve the efficiency of autonomous navigation. The average error of the practical navigation demonstrated in the meeting room is 0.10 m. The scalability of the designed system to different application scenarios is also discussed and experimentally demonstrated. Hence, the usefulness of the proposed UWB sensor applied to UVC disinfection vehicles to prevent COVID-19 infection is verified by employing it to sterilize indoor environments without human operation.
Highlights
The synchronization of anchors is necessary to implement the UWB positioning system with the time difference of arrival (TDOA) algorithm because the clock frequency ratio (CFR) and transmitting time offset vary in different devices
These results show that the generalized traversal path planning, using the edge searching method, helps find optimal solutions when the map is expressed as target nodes, inaccessible nodes, and accessible nodes
The simulated and measured results show that the Gradient Descent (GD)-Taylor method possesses high accuracy and short computing time
Summary
To combat the highly infectious nature of the global health crisis, e.g., the COVID19 pandemic disease, many intelligent-manufactured innovations have been launching to prevent infection by applying and integrating high-tech equipment. It can be used to sterilize in air and water or on the surface, showing the effectiveness of UVC when sterilizing indoors [3,4]. Direct UVC exposure is harmful to the skin and eyes [5,6,7], and an immobile disinfection system cannot be used to sterilize in some areas hidden behind obstacles. The autonomous disinfection vehicle without human operation is suitable for this dirty, dull, and dangerous task [8]. An ultra-wideband (UWB) positioning sensor is applied to a disinfection vehicle with a UVC lamp [9] to enable the vehicle to navigate autonomously and thoroughly sterilize the GPS-denied environments without human operation
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