Encoders & position sensors

Measures rotational or linear position for feedback. Motor-side and output-side measurements describe different parts of a joint.

How a magnetic encoder senses rotation

Rotate the two-pole magnet above a stationary sensor. Open the sensor package and follow shaft angle into an ideal digital reading.

Drag to rotate · pinch / scroll to zoom

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Magnet, sensor & angle output

The magnet rotates; the Hall sensor and circuit board stay still.

Ideal 14-bit code
0
Positions per turn
16,384

Ideal readout, not measured accuracy. The coloured halves mark opposite magnetic poles.

Source & model scope

Original Korthos illustration of on-axis magnetic sensing, using the AS5048A as the functional reference. Package internals, PCB traces, components, dimensions and spacing are illustrative; this is not the SpryDrive board or the chip’s recovered die layout. The 14-bit readout is an ideal angle-to-code mapping with zero offset. It does not predict sensor accuracy, noise or magnetic-field strength.

AS5048A technical reference · Illustration source · Model scope & reuse

Representative products

Component directory
Architecture, materials & specificationsArchitecture options, material requirements and integration constraints

Architecture options

ApproachMechanismAdvantagesTrade-offs
OpticalA detector reads a patterned scale.Supports fine position measurement without a magnetic target.Scale cleanliness, alignment and protection affect installed accuracy.
MagneticSensors read the field from a magnetic target.Works without a clear optical path.Target alignment and stray fields from nearby motors affect measurement.
InductiveConductive patterns couple electromagnetic signals across a gap.Can use compact PCB-based sensing without a permanent-magnet target.Target geometry, spacing and electronics determine accuracy.
CapacitivePatterned electrodes sense position through electric-field coupling.Offers another compact option without an optical scale or magnetic target.Installation tolerances and the sensing electronics still constrain performance.

Specifications & operating limits

Resolution is the smallest reported position step. Accuracy is closeness to the true position; repeatability is how consistently the same position is reported. More bits can give finer steps without improving installed accuracy.

Materials & constraints

Scale or target
Glass, metal or magnetic material depends on the sensing method.
Electronics
Photodetectors or sensing circuits convert position into a signal.
PCB conductors
Form sensing patterns in inductive designs.

Dependencies & engineering limits

Mounting & accuracy
An off-centre scale, tilted mounting or moving bearing axis adds position error. These installation errors affect accuracy independently of resolution.
Bearings
Assembly & verification
Installed alignment and signal quality can vary across the motion range. Calibrating predictable error can improve results, but it does not remove looseness or changing deformation.
Timing & control response
The controller needs the correct interface and timely readings. Transmission delay and inconsistent timing affect the feedback loop even when the measured position is accurate.
Compute & control
Sensor location & what is known
A motor-side encoder measures before the gearbox; an output-side encoder measures after it. Transmission play and twist can make those positions differ under load.
Strain-wave / harmonic reducers

Manufacturing & assembly

Guide

About this route

The route shows one process or architecture. Select a step to see its function and connections; related parts can be parallel inputs or alternatives.

Function

Inputs & dependencies
Outputs & connections
Related processes & parts
Sources

Manufacturing · Representative route. Scale manufacture and readhead installation lead to measurement of the completed axis.

Related parts & processes 4

Scale substrate

A glass or metal ring or disc carries the markings that encode angle. Another construction wraps a linear scale around a shaft.

Uneven spacing of the markings introduces angle-measurement error.

Sources & technical scope

Illustrative images of generic materials and components.

Link to this detail

Market context

RLS · encoders selected for AIDIN joints

AIDIN selected RLS AksIM-2 absolute encoders for each quadruped joint. The selected 20-bit configuration uses SSI and BiSS-C interfaces; a dual-encoder joint was described as a future design.

Renishaw

Renishaw is expanding encoder production and redesigning some existing products around components in short supply. Its magnetic-encoder sales grew with industrial automation and robotics demand, while semiconductor demand drove optical-encoder growth.

Explore documented supply relationships →