Controlling Motion in the World’s Largest Warehouses

Magnetic Encoders Drive Robots

Behind the scenes of your online purchases, portable robots are navigating the floors of automated warehouses and picking your items for you. These robots are called autonomous guided vehicles —AGVs for short — and they are powered, in part, by Timken® magnetic encoders.

Encoders use sensing technology to identify changes in magnetic fields.  The role of Timken® magnetic encoders is to help with the navigation of each AGV. Without them, they could run into each other — or not run at all.

“Imagine the precision needed to position an AGV’s robotic arm to pick a tote containing something like a bottle of aspirin in a giant warehouse,” says John Santos, chief engineer, sensor products. “Timken magnetic encoders provide the speed and position feedback that accurately guide AGVs to the correct destination.”

The result is a well-orchestrated logistical dance, where products are picked accurately and shipped on time to consumers from the world’s largest retailers.

AGVs are part of an automation trend that is changing online and brick-and-mortar retail. Large retailers intend for robots to handle the manual, repetitive tasks of order picking while people manage more complex work like quality control and customer support. The result: consumers get products more quickly; companies work more efficiently.

“Timken magnetic encoders provide the speed and position feedback that accurately guide AGVs to the correct destination.”

John Santos
chief engineer, sensor products, Cone Drive by Timken

A New Generation of Sensing

Traditionally, optical encoders — like the one you might find in your computer mouse — were used to control motion in applications like machine tools, robotics and assembly devices. Because optical designs use line-of-sight sensing to create signals, they work well in clean and quiet operating environments.

Add dust, debris, high humidity, vibration and other shock conditions, however, and things get tricky. In the last 20 years, applications like warehouses, paper production facilities and automotive manufacturing have integrated more automation into their systems. As a result, equipment builders have needed sensing solutions that can handle the imperfect conditions in those operating environments.

In response, Timken engineers patented magnetic encoder designs with Hall-effect technology to obtain high resolution from a durable magnetic target disc. Magnetic sensing doesn’t need a clean environment to work accurately.

Timken magnetic encoders were first used in automotive electric power steering sensors to improve accuracy and efficiency of assisted steering. In cars, the devices help sense the position and torque applied to a steering column as a driver turns the wheel. Then, software converts those signals into appropriate output through the motor.

The concept is the same in AGVs where a new, fifth generation of magnetic encoders is applied. These encoders are the communication linchpins between AGV steering columns and motors, helping to control a unit’s speed and position so the robot is always in the right place at the right time.

“Uptime is crucial because if you lose encoders in those areas, you shut down the heart of the robot,” says Santos. “We are known for our reliability. With our automotive customers, we have a single digit parts-per-million failure rate.”

Cracking the Code for Reliability and Resolution

Timken has worked with AGV motor suppliers over the last five years to customize this technology for their applications. Now, the company is transitioning to production as the world’s largest retailers implement the technology in more facilities.

Timken engineers arrived at today’s magnetic encoder design through extensive research, development and real-world testing in automated warehouses where retailers are experimenting with the technology before they apply it more broadly. Working with multiple AGV manufacturers, Timken customized prototypes to each customer’s motor design. Then, the magnetic encoders were subjected to the unique debris, vibration and shock conditions in the test warehouses. Consistently, the results were positive.

“By using Timken magnetic encoders, AGV manufacturers have eliminated the typical failure modes they were seeing with optical encoder options,” says Santos. “In this product line we are developing and manufacturing sensors instead of bearings, but our approach is the same. Our design world is always at the interface between rotating and fixed components and understanding how tolerances and loads affect that interface.”

The result is a sensing solution that is low profile, robust and high resolution, which are all keys for success in the AGV market, as they figuratively find and move needles in haystacks.

Learn more about Timken solutions for automated warehouses in this article about the company’s Rollon® telescopic rail systems.