A robot has drowned itself by driving into a pool.

The company markets the security robot as better than real guards in part because it never gets bored of what it does. But it appears to have looked to put an end to that work and has driven into a pond.

Pictures from the Georgetown Waterfront – the shopping centre and office complex where the robot worked – show staff members looking to decide how best to fish the now defunct robot out of the pool.

When the robot works, it is able to understand its own environment and judge whether something is wrong, using a combination of microphones, video cameras and other sensors. In the future it's expected to get other features like gun detection and artificial intelligence.

If it detects that something is wrong then it can squeak, whistle and make other loud noises intended to dissuade criminals and others from causing a nuisance.

The Knightscope security robot, which looks something like a rounded dalek, is a cheap way of patrolling around sensitive and public areas. It costs only $7 per hour to rent out, and has extra skills including the ability to withstand attack and not to get bored, freeing people from having to carry out dull patrols.

But the Knightscope robot has run into a number of problems. Earlier this year, it emerged that a drunken man had tried to assault one of the machines while it was out on patrol, and another had knocked over a toddler.