What is a Servo Drive?

Servo drives are critical components in countless systems across numerous applications – from precision CNC machines and industrial robotics to advanced medical equipment. Their role is to precisely control how motors move in response to changes in the environment and various commands at ultra-fast feedback times.

In this post from the team at Celera Motion, we’re going to take a comprehensive look at servo drives: what they are, how they work, the different types you’ll encounter, and where they’re applied. You might be looking for a quick overview or a deeper technical dive, either way, you’ll find everything you need to know about servo drives and more.

Definition of a Servo Drive

A servo drive is an electronic device that controls the movement of a motor. This includes how fast or slow the motor spins, the direction it spins, and whether it spins at all. Servo drives achieve this by adjusting the voltage and current supplied to the motor in real time.

By constantly receiving feedback from the system, a servo drive ensures that the motor responds accurately to control commands. Without a servo drive, motor movement would be unpredictable and uncontrolled, making precise operation impossible.

Technical Explanation of a Servo Drive

A servo drive is an electronic amplifier used in servomechanisms to regulate the current/voltage output to the motor. Servo drives are part of a continuous feedback loop between a sensor (or multiple sensors) monitoring the motor and the motion controller, receiving low-voltage commands from the controller, and amplifying them to achieve a given result.

Although the principal role of a servo drive is to control the motor dependent servo loop, different protocols apply to different mechanical systems.

Now we understand the basics of a servo drive, let’s learn more about exactly how servo drives work.

How do Servo Drives work?

At the core, a servo drive takes command signals from a controller, makes comparisons with real-time feedback signals from the motor, and makes live adjustments to voltage and current so that the motor behaves effectively and safely as intended. Essentially, the servo drive is constantly monitoring and correcting the movement of the motor.

Closed feedback loop

This closed-loop feedback system allows the servo drive to precisely control motor parameters like speed, direction, and torque in a wide variety of environments that require split-section adjustments.

To do this, the servo drive continuously compares the desired motion (what you want the motor to do) with the actual motion (what’s actually happening). If there’s any mismatch, it immediately calculates how much correction is needed and adjusts the motor’s electrical input accordingly.

A constant feedback loop is what makes servo drives essential for tasks that require high levels of accuracy and responsiveness.

System complexity

How a servo drive works can depend on the complexity of the system it’s within. For some applications, you only need a simple, standalone motor system that doesn’t need to interact much with others. But for more advanced systems, you may need a whole network of motors working together seamlessly.

This is where things get a bit more interesting, and we need to start talking about the different types of servomechanism control configurations.

Different Servomechanism Control Configurations

In motion control systems, axes refer to the individual points or directions of movement that are controlled by servo drives. These could be linear movements (like up/down, forward/backward) or rotational movements (like spinning or rotating around a fixed point).

Standalone axes that are not precisely coordinated with other axes often utilize a loosely coupled distributed control configuration in which the servo drive carries out path planning, as well as the position and velocity control loops. This reduces the computational strain on the master controller and allows for a faster network.

On the other hand, closely integrated networks of coordinated axes with load-dependent servo loops and dynamic loads that change in real-time require a tighter coupling, either as a distributed or a centralized control network. Tightly coupled configurations are required for high-performance systems. Distributed control networks give path planning tasks to the master, while centralized controls limit servo drive tasks to current control alone.

Essentially, simpler systems with independent axes need less coordination, allowing for faster control. In contrast, more complex systems with coordinated axes require tighter control configurations to guarantee high performance and precise motion.

Servo Drive vs. Other Motor Controllers

In motion control systems, axes refer to the individual points or directions of movement that are controlled by servo drives. These could be linear movements (like up/down, forward/backward) or rotational movements (like spinning or rotating around a fixed point).

Standalone axes that are not precisely coordinated with other axes often utilize a loosely coupled distributed control configuration in which the servo drive carries out path planning, as well as the position and velocity control loops. This reduces the computational strain on the master controller and allows for a faster network.

On the other hand, closely integrated networks of coordinated axes with load-dependent servo loops and dynamic loads that change in real-time require a tighter coupling, either as a distributed or a centralized control network. Tightly coupled configurations are required for high-performance systems. Distributed control networks give path planning tasks to the master, while centralized controls limit servo drive tasks to current control alone.

Essentially, simpler systems with independent axes need less coordination, allowing for faster control. In contrast, more complex systems with coordinated axes require tighter control configurations to guarantee high performance and precise motion.

Servo Drive vs. Other Motor Controllers

Servo drives are often compared to stepper drives and variable frequency drives (VFDs). Here’s how they can differ:

If you’re looking for precision, dynamic response, and adaptability, servo drives are the superior option.

To learn about our Integrated Stepper Motors, please visit www.novantaims.com

Types of Servo Drives

Servo drives come in all shapes and sizes, with each type suited to specific applications which depend on factors like motor design, precision requirements, and the nature of the task at hand.
In this section, we’ll break down the most common types of servo drives; DC Servo Drives.

DC Servo Drives

DC servo drives are the popular option, known for their ability to provide quick response times and smooth, precise control. These drives control motors powered by direct current (DC) and come in two variations, each with its own advantages.

Brushed DC Servo Drives

Brushed DC servo drives are the simpler of the two. They use brushes to make the electrical connection between the motor’s rotor and the power supply. They’re cost-effective and straightforward, making them a great fit for smaller, less complex systems. The downside is that the physical contact between the brushes and the components can cause wear and tear, requiring regular maintenance.

Brushed DC Servo Drives

As the name suggests, brushless DC servo drives remove the brushes altogether, offering longer lifespans, better efficiency, and less maintenance. These drives are perfect for high-performance systems that need to operate reliably for long periods without the hassle of frequent upkeep, like in aerospace or medical applications.

For more information on the comparison between brushed and brushless motor systems, check out our blog article on the topic: Brushless vs Brushed Motor: Which is Better?

Where are Servo Drives Used?

Servo Drives for Warehouse Automation

Servo drives play a critical role in warehouse automation, powering advanced systems like automated guided vehicles (AGVs) and autonomous mobile robots (AMRs). These applications demand compact, high-efficiency servo drives with excellent power density, low standby consumption, and integrated functional safety. The Denali Safe servo drive from Celera Motion’s Summit Safety Series is specifically designed for mobile robotics—delivering precise motion control and safety-certified performance in ultra-small form factors. This makes it ideal for the rigorous demands of logistics, material handling, and warehouse automation systems.

Servo Drives for Humanoid Robotics

In humanoid robotics, where lifelike motion and real-time responsiveness are essential, servo drives must combine ultra-compact design with high dynamic performance and certified safety. These robots require multi-axis coordination, low latency, and minimal heat generation for tight integration in joint actuators. The Everest S Safe servo drive from the Summit Safety Series meets these demands—offering advanced safety functions, high peak power output, and minimal footprint. It’s an ideal solution for OEMs developing next-generation humanoid robots for research, service, and industrial environments.

Servo Drives for Exoskeleton Robots

Ultra-small servo drives with high power density provide the low profile necessary for OEMs working on innovative exoskeletons for biomedical or industrial applications. These wearable solutions require tight integration with good standby power consumption and minimal heat generation while maintaining high performance to meet critical KPIs in the growing exoskeleton market.

Servo Drives for Robotics Surgery

Miniature, lightweight, high-performance servo drives are central to the ongoing revolution in surgical robotics, providing the means for conducting surgical procedures that mitigate risks to patients. Low latency, ultra-small servo drives allow robotic systems to be precise, compact, and efficient. The low latency and lag results in instant replication from the surgeon’s console to the surgical robot, delivering the precision needed for success.

Servo Drives for Industrial Robotics

Process automation has proven vital to ongoing profitability in industrial sectors, with robotics assemblies changing the face of the production line forever. These multi-axis robotic systems require tight integration and optimized heat dissipation. Ultra-precise servo drives are essential components throughout the industrial robotics sector – delivering the highest performance and efficiency while limiting energy loss through heat dissipation for overall system optimization.

Servo Drives for Radar Antennas

Radar antenna applications including airborne mobile Satcom antenna systems, and radar turntables, rely on extremely accurate and highly stable motion controllers to ensure continuous target tracking and/or satellite image locking. Servo drives designed for high-speed broadband applications are engineered for high performance in harsh environmental conditions, ensuring continued operation in extended temperature ranges, extreme mechanical/thermal shock and vibration.

Servo Drives for UVD Robots

Automated guided vehicles (AGVs) used for disinfection purposes are now commonly referred to as UVD robots. Optimal power efficiency and proper battery management directly translates to an increased operation life expectancy of the vehicle. Allowing UVD robots to operate for longer periods uninterrupted can dramatically accelerate disinfection processes. Servo drives with optimal power efficiencies and proper battery management are important requirements of UVD robots.

Advantages of Servo Drives

Servo drives are so widely used because they offer a huge number of benefits in application. Here’s a summary of some of the biggest advantages of using servo drives and why they’re worth the investment for your motion control systems.

Precision

One of the standout features of servo drives is their precision. These drives are built to make tiny adjustments to the motor’s movement, which means they can control speed, position, and torque with incredible accuracy. This is essential for applications like robotics surgery as previously discussed. One mistake in this context could be catastrophic – you need a component that can guarantee highly accurate, repeatable performance.

Efficiency

Servo drives are efficient by design, which is a big advantage for both performance and cost. They adjust the power delivered to the motor in real time, so the motor only receives the energy it needs to perform the required task.

This dynamic adjustment prevents excess energy from being used, which means less heat is generated and less power is consumed overall. As a result, the system runs more efficiently and can reduce operating costs.

Fast response time

Servo drives excel in providing fast response times, constantly adjusting to real-time feedback from the motor. This ability to make immediate corrections ensures smooth and precise motion control, even in high-speed applications.

Fast response time

As we’ve seen, servo drives are highly versatile and can be used in a wide range of industries and applications, and can be applied to simple single motor systems to large, sophisticated multi-axis systems.

Servo Drive solutions from Celera Motion, A Novanta Company

Celera Motion, offer efficient, ultra-compact, low-latency servo drives perfect for surgical robotics to humanoids and warehouse robotics.

For more information on how we can help you, contact the team today. For more information on available product ranges, please visit www.ingeniamc.com.

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