Precision rotary actuators require sophisticated positioning systems to achieve the accuracy and repeatability demanded by advanced manufacturing, semiconductor, and optical applications. These systems integrate multiple technologies to ensure sub-arcminute precision.

Positioning Accuracy Components:

Feedback System Technologies:

1. Optical Encoders

   • Incremental: Resolution to 4,194,304 pulses/rev (22-bit)

   • Absolute: Single-turn (24-bit) and multi-turn (40-bit)

   • Interpolation: 4096x interpolation for nanometer-level resolution

   • Accuracy: ±0.5 arcsec to ±5 arcsec

2. Magnetic Encoders

   • Resolution: 12-16 bits

   • Robustness in harsh environments

   • Temperature range: -40°C to 125°C

   • Immunity to contamination

3. Resolvers

   • Absolute position sensing

   • High temperature operation (>150°C)

   • Radiation and EMI resistant

   • Accuracy: ±1 arcmin to ±5 arcmin

Error Sources and Compensation:

Systematic Errors:

• Gear Errors: Periodic errors from gear manufacturing imperfections

• Bearing Runout: Radial and axial play in bearing systems

• Thermal Errors: Expansion and contraction with temperature changes

• Compliance Errors: Deflection under load

Compensation Techniques:

• Error Mapping: High-resolution error mapping and correction tables

• Thermal Compensation: Temperature sensors and predictive algorithms

• Load Compensation: Torque monitoring and stiffness compensation

• Adaptive Control: Real-time error correction based on performance feedback

Calibration Procedures:

• Laser Interferometry: Angular accuracy verification to ±0.1 arcsec

• Autocollimator Measurements: Straightness and squareness verification

• Ball Bar Testing: Circular contouring accuracy assessment

• Renishaw QC10/W: Volumetric accuracy analysis