A look under the hood of Kiva Systems warehouse robots
UPDATE: There's no better way to understand Kiva's systems than seeing it in action. Here's a video Josh Romero and I prepared:
There's been a lot of press about Kiva Systems, the Boston-area startup that developed mobile robots to automate pick-and-pack warehouse operations. No article, however, has really explained the technology that lets the Kiva robots do what they do -- swarm a warehouse by the hundreds and in a highly coordinated bot ballet deliver inventory to workers, racks of products arriving one after another in seconds, flawlessly.
Photo: Joel Eden Photography/Kiva Systems
In other words, there have been few or no details about the robots' control system, their mechanical design, and the overall resource-allocation algorithms. Until now. Spectrum has filled this gap with an in-depth article ("Three Engineers, Hundreds of Robots, One Warehouse") by yours truly in the July issue.
The two things that most impressed me about Kiva's technology were the distributed control and the robots' mechanical design.
The robots don't just follow orders from a central, know-it-all computer. They have software agents that interact with agents on a warehouse-management server and on PCs at pick-and-pack stations. All the agents act independently, each trying to optimize its own tasks using heuristic methods like greedy algorithms. What's even more interesting is that the robots, which navigate by reading barcode stickers on the floor, detect how far off their bodies are from the center of the stickers and report these readings to the warehouse server. By sharing this information -- by using a "wisdom of the crowd" approach (the proper term is distributed estimation) -- the robots can improve their navigation capabilities.
As for the bots' mechanical design, they have a lifting mechanism capable of jacking up half a ton of stuff that's one of the most beautiful pieces of machinery I've seen recently. It's a custom-machined hard-anodized aluminum ball screw powered by a single dc motor (Kiva was very forthcoming with technical details, but sorry, they didn't allow us to include photos of this piece). The really cool thing is not the screw itself, but what Kiva did to prevent the inventory rack from rotating while the screw turns: the robot's control system makes its wheels rotate in the opposite direction at the exact speed required to keep the rack motionless. Neat!
The article also has details on Kiva's business side and its three founders and early (and cold) startup days in Boston. The whole story is online, or if you're an IEEE member you can download the PDF at Xplore.