Touching distance

A rat’s whiskers enable it to find its way around, recognise objects and even build up a 3D ‘picture’ of the world. A new project could give robots the same super-sense.

While robotics researchers have concentrated on giving their machines vision systems, the pre-eminent sense of rodents – ‘touch’ via a set of whiskers – has been virtually ignored. Now, in a project just starting at the University of the West of England and the University of Sheffield, a team hope to first understand how rat’s whiskers function and then create artificial whisker sensors for their robots.

‘For most rodents the whisker system is as significant, perhaps, as vision is to sighted humans,’ comments Dr. Tony Prescott of the University of Sheffield, ‘the sensory cues discernible by the whiskers are likely to include the location, proximity, relative velocity, size, and texture of nearby surfaces and objects.’

While some current robots sport a couple of ‘whiskers’ these only warn of possible collisions. In contrast the rat can boast an awesome sensor array: ‘The rat whisker pad is arranged in a two-dimensional grid with five rows of vibrissae either side of the snout, each containing five to nine whiskers,’ explains Dr Prescott, ‘the size and geometry of this array ensures that the pattern of whisker stimulation at any one moment provides the rat with a source of three-dimensional information about its local environment.’

Not only are a rat’s whiskers highly sensitive, numerous and arranged in an optimal pattern but they are also mobile ‘the whisker system is actively controlled during exploration behaviour, for instance, the rat sweeps its whiskers back and forth across objects and surfaces in a synchronised wave at a rate of around eight ‘whisks’ per second.’

Filtering out important information from the flood of data produced by any system promises to be a major challenge. The team intend to ‘reverse engineer’ the way that a rat’s brain deals with this data as well as using classical digital signal processing techniques. In three years time, they hope to have produced a workable system.

Creating an artificial whisker system as sensitive as a rat’s will be no easy task but the rewards are considerable. We generally want to send robots where humans fear to tread, into hazardous environments that are often cramped, full of dust or smoke with limited visibility. Dr. Prescott says that: ‘in these environments a robot that can ‘feel its way’ using a rat-like whisker sense should prove extremely useful.’