Software Safety System; Hardware Safety System; Door Safety System - UVD ROBOTS UVD Robot B User Manual

User Manual for UVD Robots

3.1.1 Software safety system

The first thing the robot does is check to see if there are some software constraints on its
sensor inputs. This allows the UV-C light bulbs to be turned on, if, and only if:
● The system is running under the conditions of normal operation and low CPU use.
● If the connection with the Hardware system and the tablet exists and is active.
● If none of the human input devices indicates that the disinfection has to stop (i.e. the
emergency stop or the soft emergency stop from the tablet).
● If the disinfection process has been done in a specifically defined order.
(i.e. the person has to do the checklist, then press the physical button on the robot
and afterwards press disinfect on the tablet. If one of these steps is not done or done
in another order, the robot will never light).

3.1.2 Hardware safety system

The hardware safety comes from the constraints of a specific order of events and a parallel
system that does not allow the lights to be on more than a specific amount of time. The
events are:
● The tablet connection exists and is active.
● The tablet sends an initialising signal.
● The physical button is pressed.
● A minimum amount of time passes, so the person has time to get out of the room
(default time for this is 8 seconds).
● The level of battery is sufficient.
● A maximum amount of time is never achieved. If more time than this is passed, the
system stops (default time for a max disinfection is 30 minutes).

3.1.3 Door safety system

The tablet incorporates sensors that allow the UVD robot to know if the tablet has been
moved or not. This approach is taken for two major reasons: even though the robot is now
safely turning on the lights, it could be that a person gets to open the door or this, somehow,
opens by itself. In order to avoid this situation, the tablet is placed on the door and thus this
can measure if the door is in movement that the tablet is placed on.
The tablet has a low sensitivity movement threshold, which, if it is overcome, stops the
disinfection process. Furthermore, when the process starts, the tablet and the robot establish
a connection with a deadman signal. This is such a signal where every few milliseconds a
signal is sent and processed. If this connection exists and is active, the disinfection process
can take place. This not only ensures an immediate stop if the door is moved but also
ensures that the device and the robot are working as intended during disinfection operation.
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