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.
The term for one of our products would be ‘absolute displacement transducer’, but for simplicity, 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.
You can find further information in our technical paper ‘Position Sensors – Choosing the right sensor’.
As a custom solution, 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 Celera Motion inductive encoder 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 custom Electronics Module can also handle inputs from other elements such as switches.
Celera Motion’s Zettlex inductive encoders are generally not susceptible to emissions from other sources due to a number of factors including 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.
These sensors are suitable for automotive 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.
For all Celera Motion inductive encoder products, the air gap is specified in the product datasheet. IncOder datasheets can be found here.
Generally, it is easiest to answer this question using a couple of examples.
In a rotary example, with an Antenna O.D. of 50 mm and an I.D. of 20 mm, then the equivalent Antenna width is 15 mm (the thickness off the annulus). The maximum working distance of the Target from the Antenna will be about half the effective Antenna width, 7.5 mm. We would normally recommend a stand off distance of <1/4 Antenna width, about 3-4 mm.
If we consider a linear Antenna 10 mm wide and 100 mm long in the measurement axis, then the maximum working distance of the Target from the Antenna will be about half the Antenna width, 5 mm. We normally recommend a stand-off distance of <1/4 Antenna width, about 2-3 mm. Information on linear inductive encoders can be found here.
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.
Please complete our Contact form, and we’d be happy to discuss how we can help meet your specification needs. The first stage in developing an application-specific system is to discuss the 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 look forward to speaking with you!
Yes, it is possible in some instances of relatively simple machine control to integrate software into the microprocessor containing Celera Motion’s Zettlex inductive sensor software.
Power supply or frequency generation can also be shared between host and sensor system.
Generally, Celera Motion’s 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 applications, higher field strengths can be accommodated with the use of special targets or simple, low-cost shielding and earth planes. Our 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.
LINTRAN and IncOder product ranges are wholly unaffected by magnets.
Generally, Zettlex inductive position sensors are unaffected by DC magnetic fields because they are AC devices. However, if the magnets are within the sensor’s Near Field then they will tend to distort the Antenna’s field by providing an ‘easy route’ for the magnetic flux.
This can be accommodated in the design of the sensor by modifying the arrangement of the Transmit and Receive circuits.