[Animats]

That's a old manual Amazon facility. The newer ones use Kiva robots to bring the shelving units to the pickers, rather than the pickers going to the shelving units.

The manual system isn't that different from the Sears "schedule system" introduced in 1908.[1] Note the line "pickers don't necessarily pick items for a single or even complete order." That's crucial. Orders are split apart and combined pick lists generated. Picked items then flow towards order assembly stations, which Amazon calls "sort". At any one time, some maximum number of orders are in progress, limited by the number of output boxes at order assembly. Amazon does this with computers; Sears did it with clerks and pick slips, with Sears giving each order an assembly bin for a fixed number of minutes.

Separating picking from order assembly and inserting a sort phase reduces the order of the problem. Picking N orders from M items individually means O(N × M) cost, because as inventory becomes larger, the pickers travel more distance. With separate picking and assembly, performance is something like O(log(M) × N) cost, because each picker works in a limited area. That was Sears' big breakthrough.

[1] https://news.google.com/newspapers?nid=1734&dat=19721006&id=...

[PuffinBlue]

Kiva robots, for the curious:

https://www.youtube.com/watch?v=6KRjuuEVEZs

[EGreg]

By the way, wouldn't segways bringing people to the shelves have to expend less energy and be more efficient than kiva robots bringing shelves to the people?

[rgbrenner]

Hmm.. don't know why asking a question deserves a downvote.

I think you're right that it would be more energy efficient -- since a human weighs less than a rack full of goods.

But energy, compared to the other costs, is a fairly small component of costs.

The bigger question is whether a person is cheaper than a machine.

A few years ago before Amazon bought Kiva, they would sell a complete setup for a large warehouse for $15-20m for 1000 robots. This included a lot of setup, but even if we assume it's just 20m/1000 robots = $20,000 each.

So for $20,000 you can get a robot that will work 24/7 for a few years. Lets pretend the kiva robots are completely junk after 3 years. That's under $7000/yr.

Obviously, that's going to be tough to beat with a human. But for comparison, lets assume a person gets paid federal minimum wage ($7.25/hr), there's no overhead, no management, healthcare, never gets sick, etc. That equals $15000/year. But that's only for 40 hours a week x 52 weeks/year. So really, we'll need 3 people.. so $45000/year. (EDIT: I forgot about weekends, which is another 48 hours. So really, we need 4 people, or $60,000/year.)

Considering that humans are so much more expensive than a kiva robot, the increased energy compared to segways doesn't really effect the outcome. It's clearly cheaper to use robots and simply pay for the increased energy usage.

[patio11]

Energy is cheap; people are expensive. One kilowatt hour costs about ~80 seconds of a human's time, if the kwh and the human are both in Chicago and the human gets federal minimum wage and costs nothing in overhead.

(Any human fitting this definition is also spherical and frictionless, i.e., existing nowhere outside of physics textbooks.)

Bonus points: this remains true if one does not value money but one instead counts costs totally in carbon credits, which is one of those things that the environmental movement passionately believes and yet doesn't spend much time thinking of the implications of.

[dmv]

Not really if you define (as Amazon would) efficiency as order throughput and cost-per-order. Humans are typically more expensive than robots per hour: robots cost upfront and then maintenance + energy, but if those sum up to an hourly rate beyond the cost of humans for a jobs that humans can do at comparable quality... you wouldn't have robots yet. Kiva exists and continues to get deployed...

To fulfill an order with Kiva, a human stands at a ship station (boxes, label printing, tape) near a fast path (door, belt) to outbound. Shelves are brought, the human picks the item from the shelves and assembles the order. That's putting the humans in the loop where robotics is harder/more expensive. Your hard fulfillment rate limit is then the time it takes the human to pick and assemble the order, plus whatever time it takes the robots to bring the shelves over. This scales gracefully (install more robots until the hard latency of order fulfillment becomes robot travel time from the farthest shelf to the human, plus human time) -- robots scale with the number of shelves, humans scale with the number of fulfillment stations.

To fulfill via Segway, you tie up a human for the entire travel time between station and the traveling salesman problem of order picking and back. Or you do as Amazon was doing in this article, and split pick and pack and allow for subdividing orders between pickers, and so on. This works (obviously) and the segway approach would likely improve fulfillment speed for pickers. But it does not save operating expense (headcount).

[Lunarsm]

At my FC, pickers are moving way too quickly and navigating around all kinds of obstacles for a Segway to be practical. I believe one of the primary advantages to the Kiva method is density. Aisles can be stored closer together.

[boxcardavin]

In addition to power being cheap (as others have mentioned), the humans would experience 'downtime' when moving between stops. Downtime for humans costs a lot of money.

[nmridul]

I was wondering if the robots have to really carry the whole shelf ?

The shelves could be modified to be like automatic wending machines. The robots could just go to the shelf and the shelf will dispose the correct item to that robot. Then the robot goes to the next shelf for that order and collect all the items required for the order from different shelves and return to the packer.

The packer need to only arrange the items in the final box.

[Animats]

There are systems like that, but they're much more expensive than the Kiva system. Kiva just needs a standard, simple mobile robot base and a lot of sheet metal shelving units. It's reliable, because no one robot is essential; if one fails, another one takes over. All you need is a big warehouse with a flat floor; there's not a lot of custom mechanical engineering of conveyors and tracks.

The Kiva system is low-maintenance and low-skill. All you need on-site is someone to replace batteries and tires and clean the things; anything more than that, just ship the robots back to Kiva HQ in Massachusetts. No need for any on site engineering talent or on call maintenance.

Dispensing racks for picking systems are complex, expensive, and have single points of failure for each item. They're essentially huge vending machines. They do exist, though.[1]

Amazon has an R&D program under way to automate the picking process where the Kiva shelf unit reaches a human. They have a competition for robot picking.[2] The prize is $26,000 for a solution that will save Amazon billions.

[1] http://www.ssi-schaefer.de/en/conveying-and-picking/automati... [2] http://amazonpickingchallenge.org/

[Zombieball]

My guess is though this is entirely possible it is far too expensive to modify all the shelves to have this behaviour when you have a 1.2M sqft. facility.

[wdr1]

Amazon recently announced they would be hiring 1,000 workers in my hometown.[1]

Sorta crazy they're using robots & still need to hire that many people.

http://www.chicagotribune.com/business/ct-amazon-joliet-0811...