Linear position sensors are used in a wide variety of devices requiring linear motion detection, such as automotive components, drones used for agriculture, industrial automation equipment, audio and video mixers, medical devices, solar panel orientation systems and products using liquid level sensors and linear actuators.
Typical position sensing technologies determine position by measuring a moving element relative to the body of the sensor, which is fixed. While the most common technology is linear resistance potentiometers (POTS), there are also magnetic position sensors (MPS), linear variable differential transformers (LVDTs), linear variable inductance transducers (LVITs) as well as magnetostrictive linear displacement transducers (MLDT). Another alternative is the use of components based on reed switches, which can still be seen in some applications today.
Choosing the right technology for your system depends on key parameters and its purchase cost. Standard POTS may seem like the most cost effective solution, but considering the fact that contact technology suffer from wear and tear, this might not be the best choice because of the Total Cost of Ownership (TCO). In fact, vibrations, dirt, small particles and harsh environments can reduce the expected lifetime. The poor durability of the resistive contact POTS lead to frequent replacements of these components.
Magnetic position sensors might address the durability issues, but only for a very short stroke (no more than a few millimeters). LVDT, LVIT and MLDT are contactless technologies suitable for long linear stroke applications, but are not appropriate for many applications due to their high unit costs.
Alternative technologies based on reed switches show limitations in terms of resolution and are not cost efficient. In addition, reed switches are typically incapsulated in a tiny glass cruet, making them very fragile and sensitive to shock. Breaking even just one of the many reed switches that make up a linear sensor would compromise the performance of the entire sensor. Furthermore, changing a single reed switch is not possible as the whole linear sensor must be replaced.
Long Linear Stroke Inductive Position Sensor Example
IDT’s recently launched inductive position sensing technology is the only technology capable of overcoming all these trade-offs. Our inductive position sensing technology is contactless, prevents wear and tear, ensures superior durability, and provides the full resolution over the entire stroke. This technology can also dramatically reduce the assembly costs thanks to the simplicity of its solution, which consists of a standard 2-layer PCB, the ZMID520x IC, capacitors and a piece of metal as a target. This simple solution does not require a magnet and represents the only cost effective viable solution capable to cover up to a 1000mm linear stroke.
For more information on how position sensors can help improve reliability and flexibility for your system, visit idt.com/position.