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The trick used by hamsters to get an exercise ball rolling is helping to power a spherical robot.

Spanish researchers have found a way to mimic the shifting movement of a hamster inside a ball to get their Rosphere robot moving.

The electronics controlling the robot replace the hamster and act as a swinging weight to propel it forward.

Field trials have shown the Rosphere could help monitor soil conditions on arable land.

The Rosphere was developed by a four-strong team at the Technical University of Madrid (UPM) who tried to find a method of locomotion that would not be thwarted by uneven or difficult terrain. Wheeled and legged robots can struggle on shifting ground or places strewn with lots of large and small objects.

The rolling robot's control systems swing on a spindle that sits at the centre of the hollow spherical device. By shifting the position of the electronics package on the spindle it is possible to make the robot roll forward. Drive wheels at either end of the spindle twitch the package to get the robot moving. Operating just one drive wheel helps the robot steer.

As well as drive motors to set the control system swinging, the robot's electronics include a wireless communication system and it can be fitted with cameras and other sensors to monitor environmental conditions, such as moisture levels and temperature.

The robot can also be operated remotely so an operator can take over if it gets trapped or cannot find a way through a field of obstacles.

Early work with the Rosphere has involved rolling it along furrows between crops. Eventually its creators hope the robot will be able to travel regularly around fields to monitor conditions and tell farmers the best time to water or otherwise tend their crops.

The research effort to create the Rosphere is part of a larger European Commission funded project which is looking to make fleets of robots to help on farms.