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Passengers: The distributed multi-robot crew is as interesting as passengers Chris Pratt and Jennife

Robots: Humanoids, service bots

What it gets right about robots: Distributed robotics, pervasiveness (and limitations) of specialized robots

Recommended watching: Put this under-rated movie for your stay-cation date night and prepare to snuggle!

My guess is that you that did what I did: You took a look at the trailer and then decided to wait for it come out on DVD or cable. It didn’t seem to have enough action or "must see” special effects to be an action flick, but since it was set in space it unlikely to be a first choice for a date night chick flick. Plus the critics savaged it for having a linear organization of a predictable plot (though seriously was anyone expecting that Jennifer Lawrence and Chris Pratt were NOT going to live happily ever after? It’s like Sandra Bullock in Gravity, we’re pretty sure she is not going to die; the point of the movie is how she doesn’t die despite the numerous opportunities). As a result, Passengers is under-rated in general and is worth seeing because not having to worry about the plot gives the viewer the opportunity to savor the robots and robot spaceship.

The Passengers story is that a sleeper ship, the Avalon, is damaged in transit by an asteroid. One immediate effect is that Chris Pratt’s sleeper pod is turned off and he finds himself alone with 90 years to go on the voyage and only a few robots to interact with. He eventually wakes up Jennifer Lawrence and, as he had hoped, they fall in love. Then ooops, they fall out of love. But no wait, they have to call a truce in order to deal with the cascading failure of the ship. All ends well. Shocked. We are shocked at the happy ending. No not really, but that wasn’t the point. The point was that special effects are good, Chris Pratt is a little less goofy and more sincere than usual, Jennifer Lawrence is as adorable as ever, and Martin Sheen makes you believe his bartending android means every cliché he spouts. That’s all there is to this pleasant movie, we’re not talking a 2001: A Space Odyssey life-changing event.

But as Arthur, the bartender android, says, these are not robot questions.

The robot questions that Passengers poses are questions about distributed robots. On first glance, the Avalon appears to have a realist arrangement of robots. The spaceship itself is a robot, controlling itself and able to monitor its health. Avalon contains many independent robots, such as the small horde of cleaning robots, the waiter robots, and an android bartender, though it seems to be missing really useful maintenance robots like Huey, Dewey and Louie in Silent Running (check out my review here).

The robots, as well as digital assistants, are realistically specialized in scope and clearly engineered for a narrow set of tasks. Humorously the natural language system evinced by the intelligent systems is too constrained to actually understand the context of Chris Pratt’s questions; everything is answered as if the Avalon were about to dock at the new planet in a few months rather than in 90 years.

At the start of the movie, the robots on the Avalon read as if there are a collection of several types of robots that were operating independently. Then when the plot gets to the accelerating-cascade-failure-of-the-ship’s-systems pivot, they appear to be more strongly interconnected. It’s a big confusing. But it is an opportunity to review the taxonomy that is commonly used to describe multi-robot systems.

There are four dimensions of coordination for multi-robot systems.

  • Cooperation. Do the robots cooperate (work together to accomplish a global task) or do they compete? Bees follow pheromone trails to help bring home food. Birds flock together and maintain an efficient V flight pattern. A pack of animals might individually attack the same food source, each competing to get the best bite and thus indirectly coordinate killing the prey.

  • Knowledge. As seen in the above example, animals can be aware (birds, wolves) or unaware of each other (ants) as they work on a task. This is referred to as “knowledge,” in the sense of “knowledge of each other.”

  • Coordination. Yes, having “coordination” as a dimension of coordination sounds redundant. In this context, coordination means the robots are either implicitly coordinated, which is called weak coordination, like ants, or explicitly coordinated, or strong coordination, like the pack of wolves. Swarms in AI generally refer to insect-like weak coordination that does not require much intelligence or communication.

  • Organization. The software that enables coordination falls into three categories. One is distributed, where all the robots have their own software. They may communicate with each other (or not). Another category is weakly centralized, where the robots have their own software but a common software package or channel that lets them talk with each other, negotiate who is going to do what, etc. The third category is strongly centralized, where one of the robots is the leader and all significant decisions are made by it.

Note that "strongly centralized” is not popular in robotics research. That is because having one computer in charge of multiple robots does not fit the ideal of multiple robots; if the robots don’t have some degree of independence, then they are just appendages of the master computer. Note that research tends to stay away from centralized systems because they are highly vulnerable to that central computer failing, as the Trade Federation found out in The Phantom Menace.

In Passengers, the robots initially appear to be unaware of the other species of robots. The little cleaning robots seem to work in a pack and they could be a swarm or a local strongly centralized system. As the movie progresses, it becomes apparent that all the systems are tied together into a centralized software architecture so that when the spaceship begins to fail, the robots fail too. The cleaning robots become the canaries for a massive system failure, though that doesn’t quite make sense. If your Internet of Things refrigerator goes on the fritz, why would that impact your robot vacuum cleaner? And why would having to replace your vacuum cleaner mean you should check your heating and air conditioner for an imminent failure? How much more expensive would it be that all the aspects of your house built so that every other system was tied into it? Dependencies and centralized control are not necessarily robust, practical, or economical design strategies. But they can add dramatic tension.

My recommendation is to break this out for your next stay-cation date night and enjoy the comfortable personas of the actors and robots. Sure, you can nitpick about the science and the plot, but really the movie is an opportunity to snuggle. After watching, check out the Hollywood Reporters article and see if you agree that reorganizing the movie would have made it stronger.

- Robin

For an audio review of 'Passengers', simply click below...

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