Choosing the Best Advanced Precision Motor for Robotics and Automation

Advanced robotics and automation are demanding new, precise motion-control solutions. Here's how design engineers can choose the best ones for their applications.

Frameless BLDC motor designs like Sensata’s model DIP34 allow for the motor to be fully integrated within a given assembly. (Image source: Sensata)

People have been improving industrial processes since the first factories harnessed water and wind. Manufacturing means motion, and engineers have tried to improve industrial processes using every technology at their disposal—from motion-efficiency studies in human workers to advanced management paperwork systems.

With the advances in automation technology, the current trend has been less toward making humans more efficient, and more toward making more efficient robotics and automated production systems. This puts additional pressure on process engineers to develop motion-enabled solutions that are powerful, small, precise, and efficient. Being cost effective would also be a plus.

Electric motors have been around for over a hundred years. (The electric trolley has existed since the late 19th century.) But the first designs were large, inefficient, and imprecise. The advent of rare-earth magnets and advanced brushless DC (BLDC) motor design has empowered a new range of motors small enough to fit into confined spaces, powerful enough to do real work, and efficient enough to be used in wireless or remote applications.

The pressure to make products that are both highly functional yet cost effective means that electronic engineers must draw the optimum performance out of every system they design.

High-performance BLDC motors can provide the levels of output and economy that today’s demanding applications require. In the case of industrial systems, this means that you can put enough functionality in a robotic arm to do real work while having it run efficiently, serve reliably, and generate very little waste heat or electrical noise.

Strength and Reliability

When it comes to industrial applications, the motors in robotic handling and assembly systems must be extremely reliable, cost effective, and space efficient. For example, the ability to incorporate the motor itself into a robotic arm, instead of attaching it to an external movement point, means you can put more robots in a given space. A frameless BLDC motor design—also known as a rotor/stator part set—allows for the motor to become fully integrated within an assembly, which results in the greatest torque-to-volume possible.

Most people think of planes or cars when they think of unmanned self-guiding vehicles, but the field reaches further than that. Remotely operated vehicles (ROVs) in a manufacturing environment can integrate the entire process, bridging and connecting separate portions in a factory to a seamless whole, moving parts and assemblies from the end of one line to the beginning of the next.

There are examples of useful industrial roving systems at both ends of the scale, as not all ROVs are the size of a golf cart. For example, the inspection-class ROVs used to check out remote or human-inaccessible areas must be small and portable, so they can be easily moved to and deployed at the locations where they are needed. The latest generation of advanced BLDC motors not only meets ROV Inspection Class requirements, but their small size, power, and efficiency enable a compact design with low acoustic noise. Customizable motors serve this specialty market segment with both housed and frameless mechanical configurations.

A major advantage in an electrical system is the ability to safely operate in almost any human environment—even cleanrooms. Such an ability is impossible with a propulsion system that emits exhaust of any nature. Automated forklifts, mobile equipment carts and parts bins, shop-floor scooters, and other self-driven gear also operate much more quietly when driven by electric motors, making integration into the workplace easier.

Battery Life

A powerful electric motor operating at a relatively high duty cycle places strict demands upon its energy delivery and storage system. Additionally, the power infrastructure must be as cost effective as possible. An efficient electric motor reduces those demands. In an automated production system, most of the machines are tethered, and therefore easy to “set and forget.” But any remote system must have energy storage of some kind.

Making the most out of a battery is important to everyone, not just mission-critical systems. The person whose RC model plane tanks from a dead battery is just as upset as someone whose ROV drops a million-dollar skid of mil-spec, hand-wound solid-gold relays on a concrete floor. The biggest difference is in the money lost. That’s why the more money involved, the more robust and reliable a robotic solution must be—and that’s not just because of battery life. Everything you do that maximizes efficiency has cascading benefits across the board. The better your motors are, the better the whole system can be.

Choose Wisely

The latest frameless and brushless DC motors come in multiple configurations—the best to fit specific application spaces. The more torque you can pack into a space may not be as important as precision or other performance capacities not directly related to force. In harsh environments like oil and gas applications, motors need to perform at up to 205°C and 30,000 PSI, while handling shocks in excess of 1000g and vibration of 25g RMS.

Factory environments can be quite harsh in ways not involving shake, rattle, and roll. Often, there is a working fluid, secondary moisture, or a downright wet environment. Motors used in these environments must be able to run efficiently enough to be packaged sufficiently to resist solvents, corrosives, or other potentially toxic and hazardous environments. If a motor overheats because it can’t dump all the heat it produces, you are in serious trouble.

The spread of advanced automation technology in manufacturing is rapidly advancing, with facilities both old and new implementing the latest in smart manufacturing and intelligent robotic systems. The need for precise motion control is driven by many demands now placed on the line, from moving products around on the manufacturing floor to a variety of work stations to the logistics of moving the finished product through a facility. Having the proper motion solution can greatly reduce this pressure for the designer.

Walter Smith is a senior applications engineer at Sensata Technologies, where he specializes in brushless DC (BLDC) motors

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