Motion trends: Linear actuators leverage modularity and connectivity

Applications of small motor-driven actuators are proliferating — and in a lot of cases, the supplier integrates the rotary-to-linear device to OEM or design-engineer specification. Shown here is a PFCL25-24 from the Nippon Pulse America Inc. LINEARSTEP series — a standalone actuator that needs no external feedback or bearings. Elimination of additional mechanical power transmission makes for pump, hexapod, medical syringe, or miniature-stage actuation that costs far less than that of conventional stepper-motor-based assemblies.

Pre-integration is a common refrain in the motion industry — and actuators lead this trend. Some of the fastest growth is in motion designs destined for compact applications, many of which are being automated for the first time.

“We’ve seen the most rapid growth in applications using NEMA 34 and 60-mm and smaller motors — including those in hybrid stepper, step servo, servo, and BLDC variations,” said John Good of PBC Linear.

It’s estimated that these smaller motors reflect 60 to 70% of the market unit volume — and that aligns with our strategic partnership with Moons’ Industries, added Good.

“Many of these applications are in robotic handling systems, syringe pumps, 3D printers, and comparable motion designs … in fact, these motors are ubiquitous in an array of industries. Often, the applications for these motors need conversion of rotary to linear motion.”

So end users in the past bought the motor (as well as a coupling and screw) and then did the assembly in-house. But today, OEMs in particular are looking to migrate beyond the component strategy; buy turnkey motion subsystems; and focus on their core processes.

“This applies to projects needing 100 or 1,000 axes to (in some cases) larger design projects that ultimately involve 10,000 axes — for sale of some product into a consumer, lab automation, or medical market, for example. We sell into many such applications and focus on becoming a collaborative engineering partner to customers,” concluded Good.

One trend in motion design is pre-integration of linear systems. This is an XYZ table from PBC Linear that incorporates axes based Integral-V Technology (IVT) aluminum framing with V races. IVT components work with or without structural supports; hardened stainless raceways embedded in the Integral-V rail reduce mounting and fastening requirements. Made with the SIMO machining process, the rails maintain alignment on critical sides for accuracy in material handling, machine-tool, and other large-format applications. Speeds are to 10 m/sec and axis strokes are to 3,650 mm with longer continuous lengths possible.

It’s becoming increasingly common to purchase Cartesian robots as finished subassemblies. “We size, select, and quote components and then offer finished Cartesian robots as kits (for onsite assembly) or fully assembled robots,” explained senior automation engineer Rich Hansen of Bosch Rexroth. More specifically, EasyHandling Cartesian robots are custom built with standard catalog components — but then assembled and sold as a completed value-add design by the manufacturer. Custom subassemblies come from the factory and might include any number of linear-motion components and servo-drive motors … but strict product-development methods ensure overall safety and service life.

Because design engineers can choose between assembling components or getting them pre-assembled, they can dictate how much time and effort is put into design and integration tasks. What’s more, sometimes motion-component suppliers are willing to assume some of the system programming.

“Besides design and mechanical assembly services, we offer a degree of control engineering support … so engineers can elect to have systems arrive with pre-parameterized servo drives, simple motion validated, or even customized motion controls,” said Rich Hansen, senior automation engineer at Bosch Rexroth.

“We also have a network of trained and skilled distributors with engineering expertise — to design, source, and install complete systems from drive, motion, and control technologies,” added Kevin Gingerich of Bosch Rexroth.

Design engineers can expect at least some of that support at the distributor level from other manufacturers. Basic services related motor and drive matching and integration for specific applications are among those provided through manufacturer-distributor partnerships. But Laura May of Thomson Industries underscores supplier-level help (and component-design concepts) to make today’s motion design easier.

PBC Linear offers smart motion components to support IIoT (I4.0) functionality and cites 10 advantages for machine builders when combining enhanced mechanical components with smart motors. These include lower design costs due to reduced wiring and design simplification; more compact designs that integrate (among other things) drivers, controllers, and amplifiers; fewer sensors and I/O; less troubleshooting; streamlined commissioning; modular integration; automated adjustments to boost design flexibility and speed; the ability to leverage preventative; and increased throughput and performance.

“Value-add services are indispensable in many of today’s actuator applications. Smart actuators integrate functionalities that used to necessitate external components — including potentiometers, rotary encoders, relays, network switches, and controllers,” said May. “Embedding such functionality makes for smaller design footprints and reduced costs for purchasing, installing, and maintaining such equipment.”

Smart actuators integrate electronics within the actuator housing which lets signals from a common external source (such as a programmable logic controller or PLC) automatically manage switching, synchronization, and networking. Image courtesy Thomson Industries

Getting the right features integrated — without sensors or other electronics that would unduly add cost — requires forethought though.

“Many if not most of the applications we serve involve some degree of customization, usually to help design engineers build something new … or better integrate their systems,” explained May.

Sometimes customization takes the form of something simple — as a special adapter or cable connector out of the actuator. “Other times, design engineers approach us with a clean sheet of paper, and we collaborate with them to build something new,” said May. For example, OEMs sometimes need an axis to move faster than a standard product would allow. Here, May’s company like others involves itself in the programming. “On the software side, we’ve assisted with coding to help design engineers take full advantage of built-in communications capabilities,” she added.

IoT in automation and motion-design installations

With so much connectivity and programming support for electric-actuator applications, IoT functionality (for IIoT or Industry 4.0 applications) is a natural next step. After all, components with electronic communications (I/O, controls, cables and connectors, HMIs, sensors, drives, and so on) are gathering and using and transmitting more data than ever. Read more about this trend in our dedicated section on motion-system IoT and connectivity.

“We’re making significant contributions to IIoT advancements with the smart-actuator initiative … integrating electronics into actuators to let users network electric actuators into systems and replace rigid fluid-power systems,” said May of Thomson. Cleaner electric-actuator technologies are programmable and lower maintenance — and impart an analytical perspective that leverages sensor data and load monitoring to help users track the status of the load in real time — which in turn allows continuous performance optimization, she added.

By embedding intelligence and communications into actuators, we make it easier to track compliance and product reports, explained May. Embedded intelligence also simplifies factory testing of products before integration.

“It’s true that only a small percentage of customers use IoT extensively … but the ones that monitor operational data points can increase operational efficiency to positively impact profits. The ROI is there but the journey is long, and the commitment must be long term,” added Steven Feketa of LinMot.

(Safe) motion for mobile and battery powered designs

At present, mobile equipment and robotics are growth industries for motion control. In fact, the global mobile-robot market could grow from $4,5000 million to $10,600 million by 2020, according to research by MarketsandMarkets. These are for so-called professional service robots — used in logistics, inspection and maintenance, telepresence, and off-road robotics applications.

According to Feketa of LinMot, currently leading applications are automated guided vehicles (AGVs), all-terrain vehicles (ATVs), and similar battery-powered robotics. LinMot USA sells tubular direct-drive linear motors and linear-rotary motors into such designs.

May of Thomson Industries agrees. “We sell actuator setups for a variety of AGVs, including warehouse robots and automated parking garages, as many such applications need actuators with short strokes to help adjust payload up or down as the vehicle approaches a pickup or drop-off point,” she explained. Here the supplier also sells precision shafting for AGVs that involve extensive rotary motion — where a high duty cycles increases the need for precision and hardness.

The manufacturer’s actuators also go into all-terrain vehicles (ATVs) and utility task vehicles (UTVs) with stringent reliability requirements. These include large agricultural and construction vehicles such as combines and earth movers … and smaller products such as commercial lawn grooming equipment, noted May.

Both Feketa of LinMot and May view electric actuators a better choice than traditional fluid-power offerings here because of their efficiency and connectivity. Expect more from Feketa on the special case of direct-drive electric actuation (and linear motors) in coming Design World editorial.

Fluid power is still indispensable to mobile equipment though — and some manufacturers that handle both electric and hydraulic power management track how technology improvements are shifting the playing field. “Coupling the power density of hydraulics with the energy density that electrics can provide creates a whole new world of combined solutions,” said Steve Zumbusch, director of technology development at Eaton’s Hydraulics business. “Along these lines, we are seeing integrated electric-powered hydraulic actuators (EHAs) developing — and a new generation of combined power formats.”

But many design engineers are on a quest for lower current draw … and continually at work building out requirements for newer products that take advantage of the tremendous advances that are being made in battery technology, explained May. Case in point: Electric actuators operate only when needed — which contrasts with always-on fluid power systems … so excel on forklifts and material handlers that are charged only overnight.

“Electric actuators can also accept commands and provide status information in return — including position and speed and safety-related data such as load or temperature,” added May of Thomson.

Because of their unique self-guiding nature, some AGVs and battery-powered mobility designs are spurring new modes of connected safety. “Here, we see functional use of Safe Motion — as well as drives with Ethernet interfaces and Ethernet connectivity,” said Joaquin Ocampo of Bosch Rexroth. The manufacturer offers on-drive safety controls, safety I/O, and safety — with the latter from safe-torque-off functions, SafeMotion, and safety monitoring. There’s also the offering of multiple safety protocols in single drive systems — including PROFIsafe (on PROFIBUS and PROFINET), CIP Safety (on the SERCOS automation bus), Fail Safe (on EtherCAT), and now CIP Safety (on Ethernet/IP).