(CNN) This is why we can't have nice hitchhiking robots.
HitchBOT, the cheerful hitchhiking robot that had made cross-country trips across Canada, the Netherlands and Germany, had intended to travel across the United States as well. Instead, it survived all of 300 miles on the mean streets of the U.S.A.
Two weeks after beginning its U.S. trip in Boston, the robot was vandalized in Philadelphia, the team overseeing the robot said in a statement.
"HitchBOT's trip came to an end last night in Philadelphia after having spent a little over two weeks hitchhiking and visiting sites in Boston, Salem, Gloucester, Marblehead, and New York City," the hitchBOT "family" said on its website. "Unfortunately, hitchBOT was vandalized overnight in Philadelphia; sometimes bad things happen to good robots."
Frauke Zeller, one of hitchBOT's creators, said the robot's "family" was disappointed in the incident. HitchBOT -- which consisted of bits of technology (including a GPS and a movable arm) and odds and ends such as Wellington boots and gardening gloves -- was put together by researchers from Ontario's McMaster and Ryerson universities.
"It was quite a setback, and we didn't really expect it," Zeller told CNN on Monday afternoon. "We were spoiled by the kindness of other people who had looked after hitchBOT."
HitchBOT was entirely dependent on the kindness of strangers. It traveled by itself and couldn't move on its own but required friendly humans to take it from place to place.
The robot was a social experiment intended, in part, to test human psychology when confronted with technological novelty -- kind of a "Flat Stanley" that could engage with its fellow travelers.
"HitchBOT was designed as a social robot with a personality and all the classic elements of drama, so it had a quest, and that quest was fraught with obvious dangers," creator David Harris Smith told CNN.
The pair described the hitchBOT project as "both an artwork and social robotics experiment" to The Atlantic.
"Usually, we are concerned whether we can trust robots, e.g. as helpers in our homes. But this project takes it the other way around and asks: can robots trust human beings?" they told the magazine.
Indeed, until Philadelphia, hitchBOT had led a charmed existence.
In its short life, the little robot got to sit in the cockpit of an Air Canada plane, visit Dutch art galleries and meet Santa Claus. (Perhaps it was the Santa connection that finally did hitchBOT in; Philadelphians are notoriously mean to Old Saint Nick.)
For the most part, hitchBOT's travels went smoothly. Even in the United States, the robot got a trip to Fenway Park and took in the sights in midtown Manhattan.
And YouTube personality Jesse Wellens gave it a ride near Philadelphia.
On Monday, Wellens said he had surveillance video of hitchBOT's demise, but his claim could not be confirmed. It doesn't matter; neither Zeller nor Smith want revenge.
"Our thoughts remain unchanged," said Smith. "We're not so much interested in locating or finding out who this particular individual is. ... We see this as kind of a random act and one that could have occurred anywhere, on any one of hitchBOT's journeys."
Zeller adds that the researchers have been touched by all the concern for hitchBOT through social media.
"What we see now is the outpouring of sentiment and people expressing their feelings -- thousands," she said. "We didn't expect that, and this is something you don't tend to find in typical human-robot interaction experiments."
Even before the Philadelphia incident, the team was pleased with how people dealt with hitchBOT, often playfully or thoughtfully.
The team is waiting to get hitchBOT's remains back from Philadelphia and will then decide on its next path. In a statement, the family said that more is likely to come.
"We know that many of hitchBOT's fans will be disappointed, but we want them to be assured that this great experiment is not over," the group said.
And even after losing its head, hitchBOT remained upbeat.
"My trip must come to an end for now, but my love for humans will never fade," the bot said. "Thank you to all my friends."