High-accuracy unpackaged non-contact inductive linear position sensors for Original Equipment Manufacturers
Zettlex inductive linear position sensors are non-contact, absolute linear position measuring devices. They utilise a unique inductive position sensing technique and comprise two main components – a Target and an Antenna. The Antenna is powered with an electrical supply and can be moving or stationary. An electrical output from the Antenna shows the position of the Target relative to the Antenna. The Target has no electrical connections and can be moving or stationary.
Zettlex OEM linear position sensors are supplied in unpackaged form, making them ideally suited for inclusion within a customer’s host product such as a gauging probe, actuator or wear sensor. The Target and Antenna can be attached to a host product by several different methods (depending on the specific product), including adhesive and nylon screws.
The linear position sensors are ideally suited to harsh environments where electrical contacts or optical linear position sensors would prove unreliable.
15mm stroke linear position sensor for applications such as servo control for actuators. Unpackaged for OEM use.
≤ ±5 µm
≤ 5 µm
≤ ±0.25% full-scale
Ultra lightweight linear position sensor with analogue or digital outputs. This linear position sensor is especially suitable for applications with high vibration and generous mechanical clearances. Unpackaged for OEM use.
≤ ±53.5 µm
≤ ±1% full-scale(0.5%, 0.25%, 0.1% available)
Low profile, lightweight, high-precision linear position sensor with 14 bit resolution and digital SPI output.
Have a question about our OEM linear sensors? Here we answer a selection of frequently asked questions.
If your question doesn’t appear, please get in touch with one of our experts.
Actually, the correct technical term for one of our products would be ‘absolute displacement transducer’.
But it sounds a bit of a mouthful we use the term position sensor.
Other applicable terms might include position encoder, position transmitter, rotary encoder, linear encoder, rotary sensor, shaft encoder, angle resolver, angle synchro, displacement transmitter.
The maximum number of sensors per set of electronics is determined by the maximum permissible response time per sensor. If we consider the example of a Zettlex sensor taking 1 millisecond per measurement and a maximum response time of 250 milliseconds then with a simple multiplexing scheme the maximum number of sensors is 250.
This number can be increased with a more sophisticated multiplexing algorithm, for example, sampling the less frequently used or less important sensors less frequently.
A Zettlex Electronics Module can also handle inputs from other elements such as switches.
Zettlex position sensors are generally not susceptible to emissions from other sources due to a number of factors: – the Receive circuits are arranged as balanced quadropoles (thus negating the effect of incoming plane waves), the signal from the Target is at a highly specific frequency and the sensor uses synchronous detection.
Zettlex sensors are suitable for automotive or defence applications where permissible emission susceptibility is particularly stringent.
The IncOder product range is particularly robust in harsh EMC conditions because it is housed in a metal casing which acts as a Faraday cage.
More generally, it’s easiest to answer this question using a couple of examples:
Firstly, if we consider a linear Antenna 10mm wide and 100mm long in the measurement axis, then the maximum working distance of the Target from the Antenna will be about half the Antenna width i.e. 5mm. We normally recommend a stand off distance of <1/4 Antenna width – so about 2-3mm.
In a rotary example, with an Antenna whose O.D. is 50mm and an I.D. of 20mm then the equivalent Antenna width is 15mm (the thickness off the annulus). Again the maximum working distance of the Target from the Antenna will be about half the effective Antenna width i.e. 7,5mm. We would normally recommend a stand off distance of <1/4 Antenna width – so about 3-4mm.
We have built lots of linear sensors with a maximum full scale defelection of 0,1mm and a resolution of <1micron.
For rotary devices, we have buit sensors with targets and diameters of 12.7mm.
The longest we can build from circuit board is 2,7m but it is possible to build much larger sensors using wire or tape constructions.
Firstly, a number of parameters related to ‘accuracy’ are important for sensors. These are usually linearity, resolution and repeatability. The exact parameters for any series of Zettlex sensors primarily depend on the sensor geometry and, in particular, any variability of the position of the target in axes other than the measurement axis. Other factors effect performance to a much lesser degree. As a general rule:
First of all talk to us – we might have an existing design that will suit. In case we don’t have a similar existing design, we can modify an existing one or develop a new one to suit your needs.
The first stage in developing an application specific Zettlex system is to discuss the specific technical requirements with us.
The most important aspects are sensor geometry, accuracy, speed & electronic output. From this a Requirements Specification can be drafted as a first step in the development process – we can help you do this. Zettlex follows a tried and tested development process leading to full-scale production.
Yes. It is possible in some instances of relatively simple machine control to integrate machinery control software in to the microprocessor containing the Zettlex sensor software.
Power supply, frequency generation etc. can also be shared between host and sensor system.
Generally, Zettlex position sensors are not susceptible to far field emissions up to field strengths of 150 V/m. This covers the vast majority of possible applications including most medical and aerospace applications.
However, in some defence applications higher field strengths can be accommodated with the use of special targets or simple, low-cost shielding and earth planes.
Zettlex applications comply with EN 68000 and CISPR 25 level 1 or 2.
Yes. The standard Zettlex sensor software can be parameterized to control multiple sensors of differing geometries.
In principle, a metal shield can be inserted between a sensor’s Target and an Antenna.
The skin depth through which the excitation signals can permeate limits the thickness of the metal shield. The lower the excitation frequency, the greater the thickness of permissible metal.
The maximum thickness of metal depends on the actual metal. If a metal shield is to be used then non-magnetic stainless steel is most preferred with aluminium, steel, copper or brass least preferred. Practically, metal thicknesses of <1.6mm are necessary.
By their fundamental nature Zettlex sensors do produce electromagnetic emissions. However, these emissions are small and in practice, such emissions are invisible in the Far Field due to the rapid fall off of the field at an inverse cubed rule.
Given the low emissions levels Zettlex sensors are suitable for sensors in automotive or defence applications where permissible emission levels are particularly stringent.
Practically, the materials, from which the sensor’s main components are produced, limit the operating and storage temperatures.
Importantly, the sensor’s fundamental operating principles are not affected by temperature. That means Zettlex sensors can operate in relatively low or high temperatures.
Most frequently, the effective temperature range is limited by the electronic components at –40 to 85 or 125 Celsius (i.e. industrial or automotive ranges).
However, it should be noted that the sensor’s electronics can be displaced away from the Antenna. This enables the sensors to be designed such that only the Antenna and Target are placed in harsh temperature environments whilst the Electronics are placed in a more benign environment away from, or insulated from, the harsh conditions.
Ceramic substrates for the Antennae and Target substrates can be used to increase temperature limits.
We have built sensors that can withstand constant operation at +230 Celsius and we are developing sensors for +450 Celsius.
We have built sensors to operate in -55 and -60Celsius.