Lisandro Piacentini

Interpolation is the mathematical process that subdivides the grating period of an optical or capacitive encoder into position counts finer than the physical line pitch. Understanding interpolation electronics — including the arctangent algorithm, signal conditioning requirements, and error sources — enables accurate specification of achievable resolution at a given signal quality.

Selecting a rotary encoder for a motion control application requires systematically working through environment, accuracy, form factor, protocol, and lifecycle constraints. This article provides a structured decision tree with specific technology recommendations at each branch point.

Surgical robotic systems impose the tightest combination of encoder requirements: absolute position without homing, high accuracy in a compact hollow-shaft form factor, functional safety certification, and compatibility with sterilization processes. Optical and capacitive sensing technologies dominate this application class for clearly defined engineering reasons.

Verapath optical encoder technology uses a large-area illumination and detection system with a low-coherence LED source to achieve contamination tolerance without sacrificing accuracy. This article describes the sensing architecture, signal quality characteristics, and the reliability advantages of the wide-area approach for industrial environments.

Resolvers and modern digital rotary encoders both provide angular position feedback for servo motors. Resolvers dominate applications above 150°C operating temperature where encoder electronics would fail. Below 150°C, digital encoders provide better resolution, direct digital output, and lower system integration cost. This article defines the boundary conditions for each technology.