Sensor methods
Inductive technology
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Flexible integration options with a short axial length
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Robust to environmental conditions – dirt, dust & moisture
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Not influenced by magnetic fields
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Redundant configurations or a mix of technologies possible to meet demanding safety and reliability requirements
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Many output options available, including sine/cosine, analogue, PWM, ABZ, SENT, SPI, SSI, UART
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Low cost
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Maintains accuracy with geometric misalignments
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Utilises standard printed-circuit-board process with a reliable supply chain
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High reliability (ASIL D) automotive-standard components available from a range of manufacturers
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Wide temperature range, -40°C to 160°C
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Fast response with low latency
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Scales to match motor poles and resolution requirements
Principles of operation
A transmit coil is supplied with AC current at MHz frequencies, this produces an alternating magnetic field
Where are inductive sensors used?
Automotive and off-highway
​Inductive sensors have long been established in automotive for applications with millisecond response times, such as chassis height and EGR valve position. The latest generation have micro second response times allowing measurement of electric motor position, often in the permanent magnet synchronous (PMSM) traction motors.
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Low cost
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Wide temperature range, -40°C to 160°C
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High reliability (ASIL D) automotive-standard
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Robust to environmental conditions – dirt, dust & moisture
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Not influenced by external or motor magnetic fields
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Flexible integration options
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Magnet free
Robotics
Inductive is well suited to robotic arms, where asymmetric loads can create misalignments between an encoder’s stator and rotor.
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Maintains accuracy with geometric misalignments
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Large bore, through hole geometry
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Robust to environmental conditions – dirt, dust & moisture
Industrial
Inductive technology is commonly used in bearing-less encoder designs, offering a cost-effective and highly reliable solution. Custom configurations can be developed to meet specific accuracy and misalignment tolerance requirements.
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Bearingless
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Maintains accuracy with geometric misalignments
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Large bore, through hole geometry
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Robust to environmental conditions – dirt, dust & moisture
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Wide temperature range, -40°C to 160°C
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Fast response with low latency
Where and when to use inductive sensors
​If you are evaluating sensor technologies, especially comparing Hall effect vs. inductive, here is when inductive is the right fit:
Choose inductive sensors when you need:
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High tolerance to misalignment: Ideal for through-hole or off-axis measurements where mechanical tolerances are loose but high accuracy is still required.
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Magnet free sensing & immunity to magnetic fields: Robust in environments with strong or variable magnetic interference.
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Compact axial length: Useful in space-constrained designs.
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Flexible geometry: Perfect for custom shapes, linear, curved, or arc-based, where coil design adaptability is a major advantage.​​
​​When inductive might not be the best fit
While inductive sensors are versatile, there are scenarios where other technologies may be more suitable:
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Extreme environments: For continuous operation above 160°C or in high-radiation environments, resolvers are typically a better choice.
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Ultra-compact end-of-shaft sensing: For very small diameters, Hall effect sensors may be more practical. Inductive sensors can be miniaturized, but performance trade-offs may occur.
Sensor technology comparison
​Inductive sensors are often regarded as the best position sensor for harsh environments. They offer low cost, fast response and have the ability to main accuracy with geometric misalignments. However, magnetic sensors (e.g., Hall effect or magnetoresistive) and resolvers are also widely used in demanding applications, they are equally robust to oil, dirt, water etc. So how do these technologies compare?
Magnetic end of shaft sensors
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Magnetic solutions, typically comprising a magnet above a sensing IC, share many of the attributes of inductive sensors. They can be compact and cost-effective with Hall/magnetic sensors often fitting into the smallest diameter.
However, magnetic sensors have an intrinsic vulnerability to both external magnetic fields (e.g. from a motor/inverter), and temperature. Robustness to these external influences can be increased but it is often the cost of response time particularly for Hall effect.
Magnetic through-shaft sensors
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In off-axis or through-shaft configurations, the differences become more pronounced:
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A magnetic sensor acts as “point measurement,” sensing a small region of the field produced by a magnetic ring—similar to how optical encoders ‘read’ a small slice or sector of a scale disc.
This makes them highly sensitive to geometric misalignments, causing significant errors. Multiple “read-heads” can help if they are precisely located around the shaft and the results combined, however this is not a low-cost approach.
Inductive sensors
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Inductive sensors, by contrast, sense over the whole coil and target area, which is usually the entire ring or annulus around the shaft. The coil area is where misalignments are inherently averaged out / making them far more tolerant to mechanical variation—a major advantage in real-world applications.
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This robustness to misalignment is a key differentiator of inductive sensing. In many cases, we would struggle to recommend alternative technologies due to the precision assembly requirements they impose.
This robustness and magnetic field immunity are why most magnetic sensor IC suppliers now have an inductive sensor IC.
The challenge with inductive sensors is not in the final product, but in the development process: Each application requires a custom coil design, unlike magnetic sensors where a standard magnet recommendation from the IC supplier often suffices.
​​Sensor Methods was founded to address this, providing coil design and application engineering services. Our design library and propriety software make this quick and efficient, but our real value is our deep expertise gained from over 30 years of sensor design. This enables the right design choices and optimisations to deliver a dependable sensor in every application.
Resolvers
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Resolvers are a mature technology that is still widely used. Their construction using wound coils and ferromagnetic stator and rotor offers flexibility in axial length, diameter, accuracy, pole pair count and cost. These must be traded against each other, but low cost, relatively low axial length resolvers can be found in high volume automotive applications.
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They share the same averaging of geometric tolerances found in PCB based inductive sensors. The interrogating electronics for a resolver can be placed at the end of cable, so they can be built for extreme temperatures (beyond the 160°C limit of most inductive sensor ICs).
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However, resolver construction creates some key limitations.
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Lower frequencies (kHz rather than MHz) are used to interrogate the coils; the associated filtering adds a considerable delay to the measurement.
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Susceptibility to external magnetic fields. Careful placement or shielding in a motor is often required to prevent motor flux influencing the measurement.
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Accuracy is achieved from a high degree of mechanical precision in shaping parts along with the wire winding. The remaining imperfections are compensated for electronically.​
In contrast, PCB-based inductive sensors:
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Have a delay/response time of just a few microseconds without any complex compensation.
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Are intrinsically immune to magnetic fields.
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Are manufactured on a PCB, where precise construction is standard, at low-cost. No special PCB required.
Contact us ....
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For custom designed samples tailored for your application
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To work with us to integrate the technology into your products
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To expand your existing position sensing portfolio of technologies
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For sensor designs and support to allow you to manage the supply chain
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For sensor modules, or fully housed sensors through our manufacturing partners