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?
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.
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.
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).
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.
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.
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.