How do Sensors Measure Angle?

An angle is the degree of rotation of an object from a reference position about a central axis. In the engineering world, there are two types of angles requiring measurement. One is the physical or mechanical characteristic, such as the rotation of a shaft with respect to its bearing or housing. The other is a mathematical term such as the angle between two phases of alternating voltage system. Usually, sensors measure angles in a format that a computer or a machine can understand, interpret and utilize.

It is also a common practice to convert a physical characteristic into a rotational mechanical movement to measure linear displacement. For example, the distance traveled by a shaft can be translated into rotational movement by a rack and pinion arrangement. The angular position sensor attached to the arrangement then interprets the angular movement in proportion to the linear movement of the shaft.

In the market, you will find different sizes and forms of angle positioning sensors using various technologies. Generally speaking, these sensors are versatile and one can use them in all kinds of applications, such as in agriculture, commercial equipment, off-road vehicles and in automotive industries. Most of the applications above require a product suitable for operating in harsh environments, including moisture, dirt, dust, extreme temperatures and more.

For example, Forklift Position sensors measure the angle of the forks on a forklift truck. According to OSHA, one of the primary causes for tip-over accidents on forklifts is excessive speed when the machine is turning or rounding a corner. The angle position sensor on the truck helps it to remain within a safe speed and prevents overturning. This particular application also prevents accidents from unbalanced loads and limits the operation of the machine when the load is improperly positioned or balanced.

The simplest form of measuring angle is by using the gear tooth sensor. By sensing the teeth to count the rotation of a gear or wheel, engineers monitor and limit speed. Another common form of angular position measurement utilizes potentiometers. Other more sensitive and rugged types of angle sensors use optical or magnetic technology.

Traditional rotary encoders use an LED transmitter, a coded disc and a photo sensor to detect angular movement. The disc is coded with opaque and transparent sections, which transmit light in a specific manner to the photo sensors depending on the position of the disc. The photo sensor converts the light falling on to it into an electrical code. This allows the encoder to detect rotation, position, angle, etc.

Sensors that are more rugged use the Hall-Effect technology for measuring angle. This technology uses magnetic field sensing and does not require the critical positioning necessary for the components using optical methods. In both methods, accuracy of an angle sensor depends largely on its resolution. The higher the resolution, the more precise is the detection of angular movement. Sensors measuring angles using Hall-Effect technology can perform without physical contact, thereby remaining unaffected by vibration and abrupt movements. These sensors also have the added benefits of virtually unlimited lifespan.