Photo taken on Nov 15 shows the sewer robot being deployed in Wuhan, capital of Hubei province. [Photo by Li Hui/chinadaily.com.cn]

Wuhan, capital of Hubei province, has started to use robots to inspect the city's underground sewer network.

The city's water affairs authority used to send workers down to inspect underground pipes, but some are not large enough, making internal inspection impossible. In other cases, there is poisonous gas in the pipes, threatening the safety of inspectors.

Sewer robots were developed by a local company thanks to advances in the fields of electronics and motion control engineering.

They are shaped like a model car, with four wheels and a flexible, revolving head that features a high definition camera and searchlights.

A cable connects the robot to a control device operated by the inspectors, who can direct the robot's movements and see the images it transmits.