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Trevor Blumenau

Customer Care

Improve Quality and Productivity in Warehouse Operations

Inexpensive wireless pick-to-light systems put warehouse productivity in reach for everyone

Published: Wednesday, December 13, 2017 - 12:02

How does one define quality in the context of a warehouse? The perfect warehouse is clean, has everything in its place, and is easy to access. Your warehouse looks like the one below, right?

You have a perfectly accurate database table that tells you exactly where everything is, correct?  And your fast-moving products are easily accessible right near the loading dock! And all your warehouse employees have perfect attendance and never make mistakes.

Figure 1: Your warehouse. Right?


As they say, “You get what you measure.” So if you want a perfect warehouse, you should measure the “quality” of your warehouse against the perfect ideal. For example, if you want your warehouse floor to be clean, define a quality metric to track of the number of pieces of trash left on the floor, and publish the metric for all employees to see.

But a clean floor, albeit important, is not the most critical aspect of warehouse quality. There are many other metrics that should be measured as indicators of quality. In fact, as a CEO, I look at the picture of the above warehouse in horror. Where are the employees?  Where are the pickers?  Where is the activity?  Idle inventory in a warehouse is just a drain on company resources—the cost of the inventory and its depreciation, and the costly space it’s occupying.

Warehouses are about moving inventory, not storing inventory. 

Many companies are responding to shrinking product margins from the competitive forces of Amazon and Walmart by adopting a direct-to-consumer model. These changes create enormous pressures on corporate warehouses as they transform from shipping pallet, to shipping “eaches” (i.e., singles or small-batches). Consumers’ demand for variety is driving a rapid SKU (part number) proliferation, that is, a fast expansion in the number of individual items stocked in any given warehouse. The speed of processing shipments has never been more important: Customers want products in their hands in days, or even hours, not weeks. And of course, customers won’t tolerate receiving a damaged or wrong item.

In a fast-moving warehouse, with an avalanche in variety of inventory content, some very important metrics of quality that should be tracked are the number of daily mis-picks, and the number of pick lines per hour (a pick line is one item on an order or kit, and consists of at least an item number—the SKU—and quantity).

Mis-picks, picking the wrong item, is enormously costly to modern warehouses, particularly when shipping directly to consumers. If you send a customer a $1,000 camera instead of a $100 camera, are you going to get the item returned? Ship a defective product to a customer, and you’ll lose that customer. How much did it cost you to get that customer?

Along with picking accuracy, pick lines per hour are useful for evaluating the productivity of the overall warehouse, and picks per hour for a particular employee can also be useful in directly incentivizing and rewarding employees.

In a warehouse there is a trade-off between productivity, accuracy, time, and cost. These typically are lines picked per hour, percent pick errors, total time or latency of each order, and labor rate. Thus, an individual picker can slow down and reduce the error rate, but he’ll lower productivity and increase the total time needed to pick a complete order. On the other hand, a more experienced picker could pick faster with a higher accuracy, but most likely at a higher wage.

A pick-to-light (PTL) system, such as the one offered by Voodoo Robotics, has an effect on all of these: PTL systems basically involve having a light or text display beneath each item’s location in the warehouse. Having displays light up allows a picker to find inventory faster and improves the number of lines picked per hour. PTL devices also reduce the error rate because they show which items should be picked. The picker need not slow down (as much) to check her work, and so the overall time per order is reduced. And of course, you can have less experienced pickers, who might not know the layout of the warehouse as well, at lower wages, picking at higher rates because they can find things more easily.

A text-based device, such as ours, directly impacts warehouse quality metrics by:
• Showing the picker where to pick from with a light that lights up, so he doesn’t pick the wrong item.
• Showing the picker’s name on the device, with a custom tune, so that one picker doesn’t mistakenly take an item meant for another picker.
• Showing the picker the quantity to pick in a very clear way, associated with the motion and location of the pick, rather than on a printed spreadsheet, for example.
• Showing the picker the SKU, color, size (or any other relevant information for a particular warehouse) of the item to be picked in his language, again associated with the motion and location of the pick, rather than on a printed spreadsheet.
• Keeping inventory information accurate through instant cycle counts, to prevent a picker taking an item that the warehouse management system (WMS) or warehouse control system (WCS) thinks is a different item.
• Preventing restocking errors (similar to above), which can ultimately result in picking errors.

As a simple example, the picker, Jessica, might scan the barcode (or enter the ID manually) for her next pick list. Let’s say there are 11 items on that list. The Voodoo Robotics system would activate each of the 11 displays, one for each parts bin, in the warehouse. Jessica would push her cart through the appropriate aisle (pick lists normally give you the location of the bin) looking for a “lit” display, like below:

Figure 2: Voodoo Robotics wireless display device is easy to deploy and program

Jessica sees her name. So she knows this is her pick, not Fred’s. It gives her the SKU, which she can double-check against her pick list, and it shows her the number of parts, “3,” to pull. She then moves on to the next item. Once she has picked all her parts, she can acknowledge that she has finished her pick list and move on to her next pick list.

Notice the following errors she avoided:
1. No misreading or missing a line on a computer printout
2. It’s hard to pull from the wrong bin because the display is directly below the bin to pull from
3. Showing her name is confirmation that she is at her pick, not someone else’s.
4. Showing the SKU and number of parts to pull offers a cross-check that she is pulling the correct parts.
5. As a bonus, Jessica gets to her bins more quickly because she is only looking for a lit display, not having to read SKUs or bin locations printed on a rack. By the way, if you have ever tried to find an item at a big box store like Home Depot or Lowe’s looking only for the part number, you understand the problem. Even if you are in the right aisle and shelf, it can be time-consuming finding the right box. Imagine doing that all day.

A new type of PTL

Even with all the advantages of PTL, many warehouse managers shy away from it, thinking that using PTL devices is way too complicated. This is because traditional PTL systems require a lengthy and detailed ROI analysis for such a large capital expenditure (followed by mandatory support); extensive functional analysis and specifications by IT and operations; and lengthy software design and build cycles for modifications to existing warehouse management systems (WMS). Add to that a long-term commitment, as well as physical infrastructure/wiring, and you can understand why managers might hesitate to implement PTL.

Because Voodoo Robotics devices are modular, wireless, and battery operated, not hardwired, the installation cost is almost nil compared to wired PTLs. Designed to be maintained by the customer to minimize cost, they can be attached just about anywhere (think picking carts, totes, racks, put-walls, will-call areas, and forklifts) using double-sided foam tape or even tie-wraps. They are also far more economical and accessible to the average warehouse. The devices are leased, with month-to-month contracts (our starter kit for 10 devices is priced at only $430 the first month and $180 in succeeding months). These short-term contracts are particularly useful to third-party logistics companies (3PLs), and move expenses from capital expense to operational expense. The pay-as-you-go approach allows customers to scale up during busy times and cut back during quiet times.

Technology in a nutshell

Leveraging modern, secure technology, we’ve engineered these cloud-based devices (using modern IIoT protocols) to be easy to deploy and securely integrate with existing systems.  Devices can even be directly linked to existing spreadsheets. Customers with their own WMS or WCS can add devices to their system. Voodoo Robotics devices are accessed using URLs; no special coding is required. Existing RF guns or picking procedures can still be leveraged.

Each display is battery operated and connected wirelessly to a nearby hub. The hub can be mounted anywhere there is power and access to your company’s local area network (LAN), either wired or using WiFi. Multiple hubs can be used in larger warehouses. Once connected to your network, the hubs can communicate with Voodoo Robotics’ cloud servers using simple commands.

Figure 3:
Voodoo Robotics Starter Kit with 10 wireless displays and one hub is leased monthly.

All communication with the displays from either Voodoo Robotics WMS or your own WMS/WCS is done simply by sending a URL to the Voodoo Robotics server. This means that it is easy to send commands to devices from within a program like Excel or Google Spreadsheets to more sophisticated WMS or WCS systems.

Figure 4: Voodoo Robotics uses a simple, secure URL for communications

Battery status and other device parameters are easily viewable on a device dashboard. Because the displays use very little power and are lit only when needed, the displays’ AA batteries can last from months to more than a year. A dashboard alert lets you know when a device needs a battery change.

Figure 5: Devices can be maintained from the desktop (including battery tracking).

To keep costs down, you might not want or need a display at every location in the warehouse. Pareto analysis can show that deploying these devices to a few fast-moving “A” part locations may show a small individual gain in productivity and accuracy, but a dramatic impact on the aggregate overall operation. And it certainly makes sense to leverage devices for all picking cart slots, put-walls, will-call areas, forklifts, and other active areas of use.

Our devices are a fast, easy to deploy, flexible, mobile, and risk-free way to improve warehouse quality. More important, they are affordable for even modest warehouses.


About The Author

Trevor Blumenau’s picture

Trevor Blumenau

Trevor Blumenau is CEO of Voodoo Robotics. He is a professional engineer with a master’s degree in robotics from UC Berkley and has 25 years of detailed research and design experience in warehouse/manufacturing processes, controls, and innovation. Blumenau innovates technology that revolutionizes entire industries, with more than 50 patents and patents-pending.