Introduction
In the machine-building industry, and especially in CNC machines, accuracy, stability, and fast response are among the key factors that determine the quality of a machine’s performance. With advances in motion-drive technology, the use of Easy Servo systems — as a mid-range solution between stepper motors and industrial servo motors — has spread rapidly. This technology gives CNC system designers a combination of high accuracy, motion stability, and low cost.
Structure of Easy Servo
This system is made up of three main parts:
Stepper Motor:
The main motor is usually a two-phase or three-phase stepper motor with a precise step angle (1.8° or 0.9° per pulse). This motor is the most basic part of the system and produces high torque at low speeds.
Encoder:
The encoder mounted at the end of the motor shaft is responsible for position feedback. This encoder can be incremental or absolute, and it typically provides a resolution of around 1,000 to 5,000 pulses per revolution. The encoder’s data is sent to the drive so the shaft’s actual position can be compared with the commanded position.
Control Drive (Easy Servo Drive):
The drive is considered the brain of the system. Using closed-loop control algorithms such as PID control, it continuously corrects the difference between the actual position and the target position. These drives usually have communication interfaces such as Pulse/Direction or RS-485/Modbus for communicating with the machine’s main controller.
How the Easy Servo System Works
When the CNC controller sends a move command to one of the axes, the Easy Servo drive applies position pulses to the stepper motor. At the same time, the encoder continuously measures the motor shaft’s actual position and feeds it back to the drive. If there is a difference between the actual position and the commanded position (for example, due to a heavy load or sudden acceleration), the drive automatically adjusts the current and torque to compensate for the error.
This process allows the system to operate essentially without losing steps, giving it dynamic characteristics similar to a servo motor.
Advantages and Disadvantages of Using Easy Servo in CNC
Advantages:
High Positioning Accuracy: Thanks to closed-loop control, axis positioning is possible with an error of less than 0.01 mm.
No Step Loss: Unlike ordinary stepper motors, in this type of system the motor does not fall out of position even when the load increases.
Fast Response and Stable Torque: The system can adjust current and torque in real time, which improves performance during cuts and fast CNC movements.
Smooth, Vibration-Free Motion: Because of continuous encoder feedback, movements are more uniform and free of resonance.
Reduced Heat and Energy Consumption: At standstill or under light load, the motor current is automatically reduced.
Easy Installation and Setup: These drives are usually designed to be plug-and-play and do not require the complex configuration of classic servo systems.
Reasonable Cost: In terms of price, Easy Servo sits between an ordinary stepper motor and an industrial servo motor, making it an economical option for many machines.
Disadvantages:
- Higher Purchase Cost Compared to Stepper Motors:
Because Easy Servo systems include an encoder in their structure, their purchase cost is higher than that of simple stepper systems.
- Lower Maximum Speed Compared to Servo Motors:
Although these systems are faster than stepper motors, overall they cannot reach the high speeds available with servo motors.
- Limited Torque at High Speed:
In this type of system, torque decreases as speed increases, and this characteristic creates limitations in certain applications.
- More Complexity Compared to a Stepper Motor:
The need for feedback wiring and more complex drivers adds complexity to installation and troubleshooting.
- Lower Energy Efficiency Under Heavy Loads:
Compared with servo motors, this type consumes more energy during continuous, heavy-duty operation.
Application in CNC Machines
In CNC routers, laser and plasma cutting machines, three-axis and four-axis milling machines, and precision engraving machines, the use of Easy Servo is very common because of its precise control and fast response. This system improves the surface finish quality of the part, reduces positioning error, and extends the machine’s mechanical service life.
In addition, in machines that require high acceleration and rapid stopping (such as cutting machines with frequent axis direction changes), Easy Servo shows much better performance than ordinary stepper motors.
What Is the Difference Between a Servo Motor and an Easy Servo Motor?
The main difference between ordinary servo motors and Easy Servo motors (sometimes called “integrated servo motors”) lies in their structure and the way they operate. Here are some of the key differences:
Structure and Components
Ordinary Servo Motor: This type of motor usually consists of a separate electric motor, a controller (drive), and sometimes an encoder for position tracking. These components exist separately and must be connected to each other during installation.
Easy Servo Motor: In this type, the electric motor and encoder are built into a single, integrated unit. This makes installation and setup simpler and takes up less space.
Installation and Setup
Ordinary Servo Motor: Requires more complex configuration and cabling, since the separate components must be correctly connected to each other.
Easy Servo Motor: Setup is faster and easier, since minimal cabling and configuration are needed. This is useful for applications with limited space or a need for quick installation.
Application
Ordinary Servo Motor: Suitable for applications that require more flexible configuration or greater customization.
Easy Servo Motor: Ideal for applications that need quick, simple setup and where less space is available.
Cost and Maintenance
Ordinary Servo Motor: May involve higher maintenance and repair costs in the long run, since the separate components may need to be repaired or replaced.
Easy Servo Motor: Has lower maintenance costs, since there are fewer separate components that might need repair or replacement.
Important Note
Easy Servo motors may fall short of ordinary servo motors in terms of power and efficiency. This difference in power and efficiency is often due to the following reasons:
Structural Limitations: Because of the integrated design of Easy Servo motors, there can be limitations in some cases regarding size and thermal capacity. These limitations can affect the motor’s power and efficiency.
Different Applications: They are usually designed for applications that call for simple installation and limited space, and they are often used in lighter-duty applications or ones with lower motion accuracy requirements.
Lower Price: Because of their lower power and efficiency, Easy Servo motors are often priced lower than ordinary servo motors. This makes them an attractive option for projects with a limited budget or applications that do not require high power.
Comparison with Other Types of Electric Motors
Easy Servo motors can be compared with other types of electric motors, including stepper motors and simple AC/DC motors:
Compared to Stepper Motors
Stepper motors control motion with precise angular steps but lack true feedback. Easy Servo motors, by contrast, use encoder feedback to provide higher accuracy in position and speed control.
Compared to Traditional AC/DC Motors
Simple AC/DC motors are generally suited to applications with simpler control requirements and offer less positioning accuracy and motion control than Easy Servo motors.
As a result, Easy Servo motors are ideal for applications that require high accuracy and complex motion control, while stepper motors and traditional AC/DC motors are better suited to simpler applications with lower accuracy requirements.
Conclusion
Easy Servo is a smart, mid-way solution between traditional stepper motors and expensive servo motors. By taking advantage of closed-loop control technology, this system significantly increases accuracy, stability, and energy efficiency in CNC machines. For this reason, many industrial machine builders today use Easy Servo as a standard option for their motion axes.
Author: Engineer Ms. Sajjadi (Technical Engineering Department, Radonix Company)
