ROTARY SENSOR

What is a Rotary Sensor?

A rotary sensor detects changes in the angular position of a rotating object (usually a shaft). These sensors are commonly used in applications where it is necessary to control variables such as rotation, speed, or position. Rotary sensors are often referred to as encoders, resolvers, and tachogenerators. They are ideal for applications requiring frequent speed or position feedback for precise adjustments.

Types of Rotary Position Sensors

Encoders

Encoders produce pulses by detecting changes in light (optical) or magnetism (magnetic) on a rotating shaft. By counting these pulses, an encoder can indicate speed, distance, position (by counting the number of pulses over a given period of time), and direction (by checking the order of pulses in channel A vs. channel B).

Resolvers

Resolvers have three coils: a rotating coil (rotor) and two stationary coils (stators) positioned 90 degrees apart. Current is supplied to the stationary coils, and the resolver detects the shaft's position accurately by comparing the currents in the stationary coils relative to the rotating coil.

Tachogenerators

Tachogenerators are most commonly DC devices and use an armature attached to the object being measured (shaft). The armature rotates within a stationary magnetic field, and the induced voltage changes proportionally to the shaft speed (i.e., the higher the speed, the higher the voltage).

Advantages of Rotary Sensors

The primary advantage of a rotary sensor is the accurate feedback it provides to a system, enabling it to operate at high speeds, with constant torque, and at precise positions without human interaction. The appropriate technology or type of rotary sensor depends largely on the application's requirements and the technology used in that specific application.

Specifications of Rotary Sensors

When choosing rotary sensors, it’s essential to first understand what outcome is needed—whether it’s position, speed, or rotation. Some sensors can provide all three, while others, like tachogenerators, may only indicate speed and rotation.

Next, consider resolution and speed. Not every application runs at 6,000 RPM, and most would function well with 1024 pulses per revolution. However, the combination of these two factors will help determine whether the sensor can output the correct frequency for the system, and thus, which rotary sensor is most suitable.

Finally, assess the environment in which the sensor will be used. Will it be indoors or outdoors? Will it be exposed to high vibration, humidity, dust, or dirt? Also, take into account measurement specifications, such as accuracy and maximum angle.

Rotary Sensor Uses & Applications

• Conveyor technology
• Assembly and handling technology
• Testing and measuring technology
• Aerospace industry
• Automotive industry
• Drive technology
• Industrial machinery