Rotary encoders are some of the most valuable tools for measuring mechanical position and speed. By tracking the rotation of a shaft or other object, they can provide a digital signal that can be used for control or feedback purposes. If you need equipment that can provide accurate and reliable measurements, a rotary or shaft encoder is definitely worth considering.
What is a Rotary Encoder?
A rotary encoder is a type of sensor that measures the rotational movement of an object through a rotating shaft and circular coded discs. Sensors measure changes and produce output signals by tracking the number of times a shaft turns. Rotary encoders can provide precise information about the speed and position of an object.
Rotary encoders are often used in applications where it is crucial to track the movement of a rotating or moving object, such as in industrial machinery or robotics. In addition, rotary encoders can also be used inside DC motors. Rotary incremental encoders can be used to provide feedback about the position of the motor shaft, which can be used to control the speed and torque of the motor. On the other hand, rotary absolute encoders can track the absolute position of the shaft, which is useful for applications requiring precise positioning or maintain position accuracy.
How Does a Rotary Encoder Work?
A rotary encoder consists of a coded disc attached to a rotating shaft and a fixed optical sensor located nearby. The coded disc has a series of evenly spaced markings or slits that light can travel through. As the disc rotates, the optical sensor measures pulses of light interrupted by the markings on the disc. A rotary encoder works by tracking the number of pulses that are generated, producing output signals that can be used to track the position and speed of the shaft.
When attached to a circuit, the rotary encoder position can provide feedback about the speed and position of the object it is measuring. This information can then control the object’s movement or provide information to a display or other computer input devices. It can also provide information to a motion controller, which can regulate the speed and position of the object automatically.
Different types of encoders determine how the circular disc is read. The most common type is the optical encoder, which uses an LED and photo sensor to detect the markings on the disc. There are also magnetic encoders, which use a magnet and Hall effect sensor to track the position of the disc.
The circular disc also has various markings depending on the type of encoder. On an incremental rotary encoder, used in DC motors, the disc will have evenly spaced markings that produce a signal when they are interrupted by the sensor. This type of encoder can be used to track the position or speed of the shaft.
On an absolute encoder, which is used in applications that require precise positioning, the disc will have a unique set of markings for each position of the shaft. These distinctive markings allow the encoder to track the absolute position of the shaft rather than just the amount of rotation direction. They also produce a unique code that can also provide angular position information.
There are also different types of output from rotary encoders. The most common type is an analog output, which produces a voltage proportional to the shaft’s speed or position. There are also digital outputs, which produce a signal that a computer or other digital device can read. Incremental rotary encoders also produce sin and cosine signals, which can be used to track the position of the shaft more accurately. A quadrature encoder produces two square wave output signals 90 degrees out of phase with each other, which can track the position of the shaft clockwise and counterclockwise. A parallel absolute encoder produces a digital output representing the shaft’s absolute position.
When attached to a circuit, a rotary encoder can provide valuable information about the speed and position of a rotating or moving object. By tracking the number of pulses generated, the rotary encoder can give precise feedback about the object’s movement.
How Does An Encoder Work on a Motor?
Servo motors are direct current (DC) motors that rotate or spin based on input from an electronic controller. The position of the motor shaft can be precisely controlled, making servo motors ideal for applications such as robotics and CNC machines.
A feedback mechanism is required to control the position of the motor shaft. This is where the rotary encoder comes in. The rotary encoder is attached to the motor shaft and produces pulses of light interrupted by the markings on the disc. By tracking the number of pulses generated, the controller can determine the precise position of the motor shaft.
The rotary encoder is an essential component of a servo motor system; without it, precise control of the motor shaft would not be possible. You can find many types of DC motors with encoders attached, such as brushed DC motors and brushless DC motors.
Brushed DC motors are the most common type of DC motor. They have a commutator that rotates with the armature and brushes that make contact with the commutator segments. The brushes are connected to the DC power supply, and as the armature rotates, the commutator reverses the polarity of the armature winding. This causes the armature to rotate in one direction or the other, depending on the polarity of the DC power supply.
Brushless DC motors are similar to brushed DC motors, but they don’t have a commutator. Instead, they have a permanent magnet rotor and a stator with windings energized by a DC power supply. Electronic switches control the stator windings, and as they are switched on and off, they create a rotating magnetic field. This field interacts with the permanent magnet rotor to cause the rotor to rotate.
Rotary encoders are also used with other types of motors, such as stepper motors. Stepper motors are electric motors that move in discrete steps, rather than rotating continuously. They are commonly used in applications requiring precise positionings, such as 3D printers and CNC machines.
Like servo motors, stepper motors require a feedback mechanism to control the position of the motor shaft. The most common type of feedback mechanism is a rotary encoder. The rotary encoder is attached to the motor shaft and produces pulses of light interrupted by the markings on the disc. By tracking the number of pulses generated, the controller can determine the precise position of the motor shaft.
How to Use Rotary Encoder?
A rotary encoder can be used in a few different ways, depending on the application. For example, in a robotics application, the rotary encoder can be used to track the position of the robot arm so that it can be precisely controlled. In a CNC machine, the rotary encoder can be used to track the position of the cutting tool so that it can be precisely controlled.
In each of these applications, a professional will receive a digital or analog signal from the rotary encoder that is proportional to the speed or position of the shaft. This signal can then be used to control the object’s movement automatically.
A rotary encoder can also be used in a manual application, such as a knob on an audio mixer. In this case, the user would rotate the knob, and the rotary encoder would track the position of the knob. The signal from the rotary encoder can then be used to control the volume or other parameters of the audio mixer.
What are Encoders Used For?
Rotary encoders are very versatile and can be used in various applications. They are commonly used in industrial machinery, robotics, and automotive systems. In many cases, rotary encoders are the best option for measuring the speed and position of a rotating or moving object without making physical contact.
Some of the most common applications for rotary encoders include:
- Automotive systems: Rotary encoders are commonly used in automotive applications to measure the speed of the wheels or to track the steering wheel’s position.
- Robotics: Rotary encoders are often used in robotics applications to track the position of the robotic arm.
- CNC machines: Rotary encoders are used in CNC machines to track the position of the cutting tool.
- Industrial machinery: Rotary encoders are commonly used in industrial machinery to measure the speed of conveyor belts, counts, or other moving parts.
- Audio mixers: Rotary encoders can be used in audio mixers to control the volume or other parameters of the mixer.
- DC motors: Rotary encoders can be used to measure the speed of DC motors.
There are many other applications for rotary encoders, and new applications are being discovered all the time. A rotary encoder may be the best solution if you need to measure the speed or position of a rotating or moving object.
Types of Encoders
Different types of encoders can be used for many situations. The type of encoder you need will depend on the application and the required precision.
Some of the most common types of encoders include:
- Linear Encoder: A linear encoder is used to measure the position of a moving object in a straight line.
- Angle Encoder: An angle encoder is used to measure the angle of a rotating object or angular displacement.
- Absolute Encoder: An absolute encoder produces a unique code for each position of the shaft, making it ideal for applications that require precision positioning.
- Incremental Encoder: An incremental encoder produces pulses that can be used to measure speed or distance traveled using relative position, but not absolute position.
- Magnetic Encoder: Magnetic encoders operate by using a magnet to track the position of the shaft.
- Optical Encoder: An optical encoder uses an optical sensor to track the position of the shaft and offers high resolution.
- Capacitive Encoder: A capacitive encoder uses high-frequency signals to track changes in capacitance.
- Electromagnetic Encoder: An electromagnetic encoder uses an electromagnetic field and sensor to track changes in position.
- Single-Turn Encoder: A single-turn encoder is used to track one revolution of the shaft and is used for shorter applications.
- Multi-Turn Encoder: A multi-turn encoder can be used to track multiple revolutions of the shaft and is used for long assembly lines.
Difference between Incremental & Absolute Encoders?
Rotary encoders are available as both incremental and absolute encoders. An incremental encoder produces pulses that can be used to measure speed or distance traveled using relative position, but not absolute position. An absolute encoder produces a unique code for each position of the shaft, making it ideal for applications that require precision positioning.
Incremental encoders offer low cost and high reliability, but they require the user to keep track of the position manually. Absolute encoders are more expensive, but they offer higher precision and eliminate the need for the user to keep track of the position.
Absolute encoders are also the better choice for industrial applications where safety and precision are paramount, such as in medical and aerospace applications. In addition, many industries choose absolute encoders because they can continue to operate after a power outage. Incremental encoders will need to be reconfigured since they only provide information based on the relative position of another object.
Read more on “Incremental Vs Absolute Encoder: Their Differences & How to Choose?”
Conclusion
Rotary encoders are a versatile and precise way to measure the speed or position of an object using simple mechanics. Many types of encoders are available, each with its advantages and disadvantages. If you enjoyed this article, do share it on your social media.
Assun Motor has rotary encoders for DC motors for the automotive, medical, and aerospace industries, among others. We offer absolute and incremental encoders to meet the needs of our customers. Contact us today to learn more about our products and how we can help you find the perfect solution for your application.
