Choosing the Right Angle Sensor Specifications

An angle sensor or rotary sensor establishes the position of an object in relation to a reference point. The number of rotations needed for the device to move from one place to another around an axis is the method of displacement measurement.

Choosing the right kind of angle sensor

There are different kinds of rotary position sensors used today. Usually, sensors have categories based on specific parameters. The following are the specifications of commonly used angle sensors:

• Voltage supply
• Output type
• Sensing range
• Current supply
• Packaging type
• Temperature range

These parameters can narrow down the search for the exact nature of the sensor needed for an application. For example, output type is either analogue or digital.

Selecting specifications of an angle sensor

In line with the parameters identified above, measurement specifications are vital in choosing an angle sensor.

• Accuracy. The accuracy of an angle sensor refers to the output indicated in either positive or negative numerical value. Low accuracy percentages are ideal because it maximises the efficiency of the sensor.
• Maximum angle range. Simply put, it is the maximum angle the sensor can measure. Before choosing an angle sensor, specify first the maximum angle using a variety of angles then determine the mechanical range as the maximum measurable angle desired.

In addition to measurement specification, the electrical output should be equally important in the selection process.

• Analogue current. Sensors with analogue current provide excellent transference of long-distance signals. The range of the analogue current is usually 0-20mA.
• Analogue voltage. This parameter refers to the continuous function of the device’s output expressed in linear motion.
• Analogue frequency. The device encodes the output into frequency modulation or amplitude modulation. Sine waves and square waves are examples of waveforms used to represent output.
• Resistance. In this type of electrical output, the resistance measurement is in Ohms.
• Digital. A relatively recent innovation, digital electrical production uses a serial code for data interpretation, which suits applications that rely on computers.

These specifications help an engineer determine the most compatible sensor for the mechanism.

What are the kinds of angle sensors?

The different kinds of angle sensors used across industries vary by design and internal mechanism.

• Rotary potentiometers. Potentiometers are a resistive type of sensor which consists of a circular conductive track, and a shaft with a wiper.
• Hall-effect sensors. This type of angle sensor makes use of a magnetic field to produce the output. The device usually consists of a magnet, rotating shaft, and Hall element. The change in angle position of the Hall element produces changes in the magnetic field. This change in the magnetic field also leads to changes in the output voltage. For applications in harsh environments, Hall-effect sensors are more suitable.
• Resolvers. Similar to the design of a linear transducer, a resolver also contains three coils. A resolver uses a magnetic field as part of the operating principle in angle measurement.

Specific characteristics of sensors, such as contactless technology make them desirable for use in extreme conditions. When a sensor is contactless, it is not prone to wear and tear caused by friction.

This article does not necessarily reflect the opinions of the editors or management of EconoTimes.