What is a servo motor

General motors are mainly used as power sources for continuous rotation of equipment. In contrast, servo motors equipped with control mechanisms can only rotate a fixed angle and stop at precise positions. By utilizing this characteristic, servo motors are widely used in various equipment control scenarios in the industrial and hobby fields, from joint positioning of industrial robots to determining the rudder angle of radio controlled aircraft, their presence is everywhere.

Definition of servo motor

Servo motor servo（servo）It refers to the control mechanism. In the field of technology, the controlling side is called dominant（master）The controlled side is called from（slave）It is said that both servo and slave originated from LatinService(Slave).

That is to say, the meaning of the name servo motor is"Work faithfully according to instructions"As long as the motor can control the rotation position and speed, regardless of the mechanism, it is called a motor"servo motor".

Therefore, sometimes stepper motors and ironless motors are also included in servo motors. Here, we explain the type of servo motor that is equipped with an encoder (rotation detector) and uses a driver to control speed and position (angle) based on this information.

The difference between servo motor and stepper motor

Stepper motors, like servo motors, are equipped with mechanisms that control the rotation angle by receiving external signals. They can both perform equipment positioning and other operations, but have the following differences.

Control method

The servo motor detects the rotational position through an encoder (rotation detector) and feeds back the information detected by the encoder to the controller to control the position. Therefore, high-precision stopping can be achieved, even if it stops during rotation, it can return to its original position if there is a deviation in position. On the other hand, the rotation angle of the stepper motor is proportional to the number of pulses, and the driver controls the position by receiving this pulse signal from the controller. Therefore, in fact, it does not require a mechanism to detect the position, so it cannot identify the deviation of the position. So there may be a possibility of stepping out due to unexpected load fluctuations or other reasons (the indicated rotation angle is not synchronized with the motor rotation).

servo motor

stepper motor

torque/speed

Servo motors can generate stable torque in both low-speed and high-speed regions, thus enabling high-speed operation. Stepper motors are only capable of generating high torque in low-speed regions, and the torque decreases in high-speed regions, making them unsuitable for high-speed rotation applications.

cost

Servo motors are more expensive than stepper motors because they require the use of expensive rotary encoders and servo control devices (servo drivers).

The history of servo motors

Servo motor technology has made significant progress with the advancement of industrial robots.

The United States fromtwentycenturyfiftySince the era, there has been an emphasis on factory automation, and automation processes represented by belt conveyors, automation devices, industrial robots, etc. have begun. The initial automation devices and industrial robots used hydraulic and pneumatic positioning actuators, which had issues such as accuracy, stability of use, pipelines, oil and gas leakage.

Afterwards, withtwentycenturyfifty〜sixtyeraDCAs servo motor technology continues to develop and its practicality improves, it has begun to be used in industrial robots to replace problematic hydraulic and pneumatic mechanisms.

arrivedtwentycenturyeightyThe era has emergedACServo motors, robots have a trend towards pursuing smaller and lighter sizes, etc,ACDue to its high practicality, servo motors are now almost used in all industrial equipment products.

Types of servo motors

Servo motors can be divided intoDCServo motor andACThere are two types of servo motors.

DCservo motor

By brushDCA servo motor driven by a DC motor.DCMotor ratioACMotors are easy to control, small in size, and low in price, so they were widely used in the past, but withACThe development of motor control technology has led to fewer opportunities for its use nowadays.

ACservo motor

fromAC(Communication) Servo motors driven by motors. Its control ratioDCMotors are complex, but with the development of control technology, they are now the most commonly used servo motors.
ACServo motors can be divided into synchronous motors according to the type of driving motor（SM）Type and Induction（IM）Two types of types. The difference between the two lies in whether permanent magnets are used.
Synchronize（SM）Type uses permanent magnets. The higher the output power of the motor, the more expensive permanent magnets are used, resulting in higher costs. Therefore, it is mostly used in fields with low output power (insufficient)10kW）Nowadays, with the emergence of high-performance permanent magnets, synchronous type has become the mainstream product.
Induction（IM）Type does not use permanent magnets and is used in fields with high output power（10kWAbove).

The purpose of servo motors

The advantage of servo motors is precise positioning control, therefore they are widely used in the control of industrial robots and precision machinery.

• Joints of industrial robots

• The joints of humanoid robots

• Control device for food machinery

• Control device for packaging machinery

• Belt mechanism of conveying device

• Automatic doors for electric vehicles, etc

• Inspection devices for liquid crystals and semiconductors, etcX-Yworkbench

• Stamping and roller feeder

• Rotating worktable for machine tools and inspection devices

• Control of pressure devices

• Control of bonding device

• Control of resin molding machine

• Control of entertainment equipment

• The use of radio control and other hobbies

• Coating and gas-phase deposition device

• Rotating cleaning device for LCD and semiconductor

Aspina's servo motors solve customers' problems

Aspina provides brushless technologyDCSynchronization of motors（SM）Type servo motor. Additionally, it can also be provided in brushless modeDCEquipped with a rotary encoder on a motor or hybrid stepper motor, and necessary servo control through a driverACServo motor.

Aspina's servo motors are provided in the form of system components, including drive and control systems as well as mechanism design. We will provide you with a one-stop support service from trial production to mass production, and then to after-sales service.
We will also propose the best solution based on the functions and performance required by various industries, applications, and customer products, in conjunction with the customer's production system.

We not only provide services for customers with clear expectations and specifications, but also offer support from development to mass production for customers who encounter various difficulties. Please feel free to inquire. Please feel free to inquire.

I don't know what kind of motor is needed

• "We are still in the early stages of new product development and have not yet produced specific specifications and design drawings. But in order to accelerate the future development process, we hope to receive some suggestions on the motor aspect."

• "There are no experts proficient in motors in the company, and there is a lack of motor knowledge required to achieve ideal operation."

The comprehensive design of the motor and its surrounding parts is too difficult

• "We want to invest our company's resources into product planning and the design and development of core technologies. Is there any company that can fully undertake the design and development of motors and their surrounding parts in addition to this?"

• "Modifying the motor requires modifying the design of other structural components, which may require a lot of time and effort."

There are no products that meet the intended use in the existing products

• "We wanted to find customized motors designed based on our company's products, but were rejected by the cooperating motor manufacturer."

• "We want precise control of the motor, but the existing motor does not support it. Can we just give up?"