Method of calculating an exposure time for disinfecting a room using an ultraviolet disinfecting apparatus

1. A method of calculating an exposure time for disinfecting a room using an ultraviolet disinfecting apparatus,

the method comprising the steps of:

measuring distances by:

a) using a spatial sensor on the ultraviolet disinfecting apparatus, to perform a first scan of a boundary surface of the room, to measure a first set of distances from the sensor to the boundary surface;

b) adjusting the height of the spatial sensor;

c) using the spatial sensor to perform a second scan of the boundary surface of the room, to measure a second set of distances from the adjusted sensor to the boundary surface;

d) further adjusting the orientation of the spatial sensor; and

e) using the spatial sensor to perform a third scan of the boundary surface of the room, to measure a third set of distances from the further-adjusted sensor to the boundary surface;

and subsequently calculating the exposure time in dependence on the sets of distances.

2. A method according to claim 1 , wherein the first scan is arranged such that the first set of distances is measured within a substantially horizontal plane.

3. A method according to claim 1 , wherein the second scan is arranged such that the second set of distances is measured within a substantially horizontal plane.

4. A method according to claim 1 , wherein the adjusting of the orientation of the sensor is such that the sensor is orientated downwardly towards a base of the boundary surface.

5. A method according to claim 1 , wherein in step d) the orientation of the sensor is adjusted during the third scan in dependence on a rotational position of the sensor within the third scan.

6. A method according to claim 5 , wherein the orientation of the sensor is determined by:

(i) determining, for each rotational position of the third scan, the larger of the first and second distances at that corresponding rotational position;

(ii) calculating the orientation of the sensor based on the larger of the distances in step (i) and the height of the sensor.

7. A method according to claim 1 , wherein the step of calculating the exposure time comprises comparing, for each rotational position of the spatial sensor during the plurality of scans, two sets of distances to predict the distance to a wall of the room.

8. A method according to claim 1 , wherein the step of calculating the exposure time comprises comparing, for each rotational position of the spatial sensor during the plurality of scans, two sets of distances to predict a number of obstructions within the room, and adjusting the exposure time in dependence on the number of obstructions.

9. A method of disinfecting a room including the steps of:

determining the exposure time according to the method of claim 1 , and

irradiating the room with ultraviolet radiation for the exposure time.