Linear position sensors are defined as any device which converts an object’s linear movement into an analogue, digital, or electrical signal. Linear sensors are categorised into a variety of measurement principles which make these sensors versatile and suitable for diverse applications ranging from consumer products to industrial machines. This article focuses on Linear Variable Differential Transformers and the innovations that shape this technology.
How does an LVDT differ from other linear sensors?
Unlike some types of linear position sensor technology, an LVDT has a non-contact assembly. It is an electromechanical sensor which means that the output produced is electrical. The basic working principle of an LVDT has remained unchanged since it was first introduced for mainstream application almost six decades ago.
Like any transformer, the device has a primary coil responsible for inducing power into two secondary coils wound around a ferromagnetic core. The core is coupled with the object being measured using electromagnetic lines, and the elements of the sensor do not come into contact; hence, eliminating friction and the effects of wear.
Innovation in LVDT technology
Modern LVDTs benefit from manufacturing techniques that use new materials and cheaper microelectronics; thus, making these sensors more affordable and reliable. LVDTs today are also capable of greater measurement resolution.
One of the limiting factors that prevented widespread application of LVDTs was the higher cost of electronic components. These components were also bulkier and prevented installation in small spaces such as pneumatic and hydraulic cylinders.
Removal of external electronics
Micro-electronics are enabling modern LVDTs to have both signal conditioning and processing components within the sensor, rather than use an outer box. In the past, an AC-operated LVDT had a separate signal conditioner. The amount of time required to calibrate these components, as well as the need for external parts, made the application of LVDTs cost-prohibitive. These days, the incorporation of internal electronics and other components result in LVDTs that are more compact and cost-effective.
Improved sensor performance
Many industrial buyers require sensors that can perform in various conditions, including working environments that are subject to high friction, extreme temperature, and moisture. LVDTs manufactured using new materials and microelectronics make a broader industrial application possible.
Improving the stroke to length ratio of these sensors also allowed for installation in hydraulic cylinders. With lighter cores, the sensor will have a more dynamic response and reduce the overall weight of the sensor.
Experimenting with exotic construction materials allows LVDTs to perform in sulphuric environments. These sensors are also more resistant to corrosive elements as well as microorganisms present in brackish waters; hence, LVDTs are also compatible with submerged installations which are quite common in offshore oil drilling and mining operations.
Customising the sensor packaging, improving the performance, and reducing the cost make LVDTs more attractive for a wide range of modern applications. Innovations in digital technology will also likely require LVDTs that can provide the necessary performance and output required by cutting-edge machines and consumer devices. Indeed, LVDTs have unlimited potential in a world that is highly dependent on automation.