By Jane Wakefield

Back in 2015, a hitchhiker was murdered on the streets of Philadelphia.

It was no ordinary crime. The hitchhiker in question was a little robot called Hitchbot. The "death" raised an interesting question about human-robot relationship - not so much whether we can trust robots but whether the robots can trust us.

The answer, it seems, was no.

Hitchbot has now been rebuilt, at Ryerson University, in Toronto, where it was conceived.

Its story is perhaps the ultimate tale of robot destruction, made all the more poignant by the fact that it was designed to be childlike and entirely non-threatening.

With pool noodles for arms and legs, a transparent cake container for a head, a white bucket as a body, and resting on a child's car seat to allow anyone picking it up to be able to transport it safely, it was cartoon-like. If a child designed a robot, it would probably look like Hitchbot.