Big Power in Small Packages: The Revolution of Micro-Sized Servo Drives

What You’ll Learn:

The ongoing trend of micro-sized servo drive technology is driven by Moore’s Law and increasing electronic circuitry density.
Lighter, smaller and more powerful micro-sized servo drive solutions enhance efficiency and performance in applications like robotics and aerospace by reducing weight and size—minimizing torque requirements in robotic arms and lowering energy/fuel consumption in portable and mobile systems.
Micro-sized servo drives can be advantageous in some applications but the trade-off for increased power density is higher costs.
Larger drives often remain the best solution for high-power motors and less space-constrained environments.

The miniaturization trend continues as engineers strive to create compact designs without compromising performance. This is particularly evident within the electronics sector, exemplified by Gordon Moore’s principle that the number of transistors on an integrated circuit doubles approximately every two years. While the rate of miniaturization has stabilized in recent years, the demand for smaller, more efficient components remains robust.

As industry moves toward digital transformation, servo drives will increasingly contribute by helping engineers improve data integration, production efficiency and process optimization. In motion control, today’s micro-sized servo drives enable even more advancements in automation, robotics and other applications such as portable medical devices and autonomous mobile robots that require compact yet high-performance servo drives.

Today, a wide range of equipment integrates micro-sized servo drives, which enhance functionality and deliver unparalleled performance in applications demanding compact size. This article explores micro-sized servo drive technology, its benefits, design considerations, industry trends and the challenges engineers face when integrating these components into original equipment manufacturer (OEM) products.

The Rising Tide of Miniaturization

Advancements in materials science, microfabrication techniques and computational power, along with the relentless push towards miniaturization, drives continued development of components that offer equivalent or superior performance in significantly smaller footprints. In motion control, this translates to a demand for servo drives that can deliver precise, reliable control in space- and weight-constrained applications.

Miniaturization enables the creation of portable devices, embedded systems, mobile robots and complex machinery that would be impractical or impossible with traditional, larger components. Beyond reducing size, micro-sized servo drives enhance system performance, improve energy efficiency and expand the range of potential applications.

Even as the form factor significantly shrinks, their exceptional performance makes micro-sized servo drives suitable for applications ranging from mobile and collaborative robots (cobots) to complex medical devices, as well as aerospace and military applications.

Why Smaller Servo Drives Matter

Increased demand for automation across industries fuels the need for smaller servo drives. Compact servo drives integrate seamlessly into advanced robotic designs. Take, for example, a simple cobot arm with multiple links connected by joints. Each joint contains a motor and drive that enable movement and articulation. As each joint rotates, it must provide enough torque to lift all the other linkages positioned further from the base. Reducing the mass of these drives increases efficiency by reducing energy consumption (Figure 1).

Figure 1: Using lighter servo drives in the joints of the robot reduces the torque required to lift the arm.

To this effect, the trend of miniaturization directly influences mechanical system efficiency. By utilizing smaller servo drives, designers create lighter operational frameworks where reduced weight corresponds to lower energy consumption. This aspect is especially crucial in sectors such as aerospace, where minimal weight translates into substantial fuel efficiency improvements. Consequently, engineering sleek, powerful servo drives remains foundational for constructing agile and capable robotic systems.

Mobile robotic applications also benefit from smaller servo drives. Similar to the fixed cobot example, an autonomous mobile robot (AMR) or autonomous guided vehicle (AGV) with smaller and lighter servo drives on board reduces unnecessary weight and creates more space for a larger battery. Either way, the result is a robot that works harder and longer every day (Figure 2).

Figure 2: By using smaller servo drives, robots have less dead weight to deal with, reducing their wear-and-tear.

Compact, lightweight servo drives also help engineers designing portable medical and military equipment reduce weight. Identifying and developing lightweight solutions plays an important role in reducing fuel consumption in aerospace applications.

Benefits of Micro-Sized Servo Drives

Micro-sized servo drives offer many advantages, making them a compelling choice for a variety of engineering applications. These benefits extend beyond mere size reduction, encompassing improvements in performance, efficiency and overall system design. Despite their small size, micro-sized servo drives achieve remarkable power output, delivering substantial torque and speed control capabilities in a lightweight package.

An example is the FE060-60C-EM from Advanced Motion Controls, which can supply up to 60 amps continuous current to brushed, brushless, steppers and linear servo motors. This high power-to-weight ratio makes them suitable for applications where minimizing mass is critical, such as robotics, aerospace and portable medical devices (Figure 3).

Figure 3b — Figure 3: Measuring just 1.5 × 1 × 0.6 in. (38 × 25 × 16 mm) in size, Advanced Motion Controls’ FlexPro digital servo drives are suitable for space-constrained applications.

The integration of advanced control algorithms and optimized electronic components allows micro-sized servo drives to operate with exceptional energy efficiency, which contributes to lower operating costs, extended battery life in portable applications and reduced environmental impacts.

Micro-sized servo drives also provide engineers with greater freedom to design innovative products that were previously constrained by the size and weight of traditional components. Their compact form factor enables integration into tight spaces, facilitating the development of highly integrated, multi-functional systems, with either distributed or centralized control schemes (Figure 4).

Figure 4b — Designed to drive brushless and brushed DC motors at a high switching frequency, Advanced Motion Controls’ analog PCB-mount µZ (Micro-Z) servo drives weigh just 8.5 grams, output 10A peak and 5A continuous, and operate with a bus voltage range of 10-36 VDC.

In some applications, the use of micro-sized servo drives can simplify overall system design by eliminating the need for external components. For example, mounting a compact servo drive on the back of motors eliminates the need to run cables back to panel- or cabinet-mounted servo drives. By minimizing cabling, such a distributed architecture reduces the chance of electrical noise-related feedback issues and simplifies trouble shooting, repair and maintenance while improving reliability with fewer points of failure.

Micro-sized Servo Drive Application Examples

The proliferation of micro-sized servo drive applications is driven by several key applications in various industries:

In robotics, micro-sized servo drives are essential for creating lightweight, agile robots with high degrees of freedom. Cobots, inspection robots and surgical robots all benefit from the compact size, high precision and energy efficiency of these drives.

Micro-sized servo drives also enable the development of advanced medical devices such as portable infusion pumps, robotic surgery tools and prosthetic limbs. These drives offer the precise control and reliability necessary for critical medical applications, while their small size allows for the creation of more comfortable and ergonomic devices.

The aerospace industry is increasingly adopting micro-sized servo drives in applications such as flight control systems, sensor positioning mechanisms, and unmanned aerial vehicles (UAVs). The high-power density and low weight of these drives contribute to improved fuel efficiency, extended flight times and enhanced maneuverability.

In industrial automation, micro-sized servo drives are being used to enhance the performance of machines involved in manufacturing, packaging and material handling. These drives contribute to increased throughput, reduced cycle times and improved product quality.

Micro-sized servo drives are critical components in scientific instruments that require precise motion control, such as microscopes, spectrometers and analytical devices. The high accuracy and low noise characteristics of these drives enable researchers to perform experiments with greater precision and reliability.

Design Considerations and Challenges

While micro-sized servo drives offer numerous advantages, engineers must carefully consider several design factors when integrating them into OEM equipment. In accordance with Moore’s Law, electronics are becoming increasingly compact. But contrary to most computer components, servo drives must actually transmit enough power through the PCB to drive a motor—not just perform logic functions.

High-power motors require a great deal of current, and despite cooling fans, heat sinks and other thermal management techniques, a small circuit board can only handle so much current without overheating components. Furthermore, as voltage increases, the spacing between traces on a printed circuit board must also increase to prevent noise interference or arcing.

Despite their efficiency, micro-sized servo drives still generate heat during operation. Effective thermal management is essential to prevent overheating and ensure reliable performance. Heat dissipation is a major factor when trying to increase power density.

While the possible power density within the PCB itself improves, finding reliable motor and power connectors that can handle high current output without melting, which still fit neatly on the servo drives, becomes a limiting factor. Sometimes it is simply necessary to use bigger, heavier-duty servo drives for heavy-duty motion control applications (Figure 5).

Figure 5: Even with recent advancements in power density, servo drives continue to come in a wide variety of sizes, shapes and types.

Cost versus necessity is another factor to consider. Many less-compact drives can actually be easier and less expensive to manufacture, which naturally leads to lower prices. Although small drives can be very useful, if space constraints aren’t a major factor, a larger but lower-priced drive can serve the application well. For example, when designing a large gantry system with plenty of space available to mount a big servo drive, then there’s no sense paying more for a tiny servo drive that will have virtually no impact on performance.

A tiny servo drive that won’t make a significant difference in performance will not be worth the money, for example, when designing a large gantry system with plenty of space for a large servo drive.

There are times when having a bulkier servo drive is actually preferable. Larger servo drives are easier to access for maintenance. Since they are too big to be embedded deep within a large industrial machine, it’s often much easier to access a panel, or cabinet-mounted servo drive. Is it also much more convenient to simply screw in a couple D-Sub connectors and be done in 30 sec., instead of struggling with dozens of tiny clip connectors with crimped pins (Figure 6).

Figure 6: Micro-sized servo drives are not necessary, and are often impractical, on large machines.

Although the increase in demand for—and use of—smaller drives continues to expand, there will always be a need for larger servo drives. While micro-sized servo drives are becoming more cost-competitive, they can still be more expensive than traditional servo drives. It is important to weigh the cost benefits against the performance advantages when making a selection.

Design Micro-sized Servo Drives for the Long Haul

Engineers increasingly specify embedded micro-drives for cobots, AGVs, AMRs, fixed robotics, mobile robotics, animatronics, portable devices, lab automation, military equipment, aerospace, medical equipment and any application requiring a compact and lightweight solution.

By understanding the benefits, design considerations and challenges associated with these drives, engineers can harness their potential to create innovative products and systems that meet the demands of a rapidly evolving world. As technology advances and market demands shift, the integration of micro-sized servo drives will continue to be a driving force behind progress across a wide range of industries.

Jackson McKay is marketing engineer for Advanced Motion Controls. He holds a Bachelor’s degree in mechanical engineering from Cal Poly, San Luis Obispo.