Tell me about this new electronic lifeguard system

It's a new artificial intelligence (AI) system that can alert lifeguards to swimmers in difficulty, even in busy pools.

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Q.� What is the system called

A.� The Poseidon System. It has been developed by Poseidon Technologies of Boulogne, near Paris.

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Q.� How does the Poseidon System monitor the pool

A.� Through a network of underwater and overhead video cameras. AI software then analyses the images to work out what path swimmers are taking. Anyone in the water who starts to sink slowly is added to the software's 'pre-alert' list. Swimmers who then stay still on the pool bottom for�five seconds or more are considered in danger of drowning and the lifeguard is alerted.

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Q.� Why is such a sophisticated system needed to monitor what path a swimmer is taking

A.� The interplay of light, reflection and shadow underwater make distinguishing actual swimmers, and their direction, from the shadow of a swimmer cast onto the bottom or side of the pool difficult.

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Q.� So, how can Poseidon tell what's a swimmer and what's a shadow

A.� It does this by comparing the location of images of the same shape from separate cameras. Shadows will appear in the same place from different angles and so are ignored. But if they are different, the shape is a swimmer and so the system follows its path. Any swimmer that then lies still on the bottom for over 5 seconds is considered at risk and the lifeguard is alerted.

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Q.� How does the lifeguard know where the endangered swimmer is in the pool

A.� First of all Poseidon double-checks that the image really is a swimmer, rather than a shadow, by seeing whether it blocks the pool's floor when viewed from overhead. Only then, when Poseidon is sure that the immobile shape is a swimmer does it alert the lifeguard, by showing the swimmer's location on a poolside screen.

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Q.� How useful is this new system

A.� Swimmers can drown in busy swimming pools when lifeguards fail to notice that they are in trouble. The Royal Society for the Prevention of Accidents says that on average 15 people drown in British pools each year, but many more suffer major injury after getting into difficulties.

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According to its manufacturers the system has already saved one person's life at one of the seven sites currently using it.

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If you enjoyed this article and want to read about other AI systems, then why not have a look at this.

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By Lisa Cardy