RV reducer sizing: backlash and torsional stiffness are the hard specs
Positioning accuracy of a robot joint lives or dies on the stiffness chain; backlash and torsional stiffness are the two hardest links to compensate. Definitions, test methods and typical ZKRV values.
Backlash is the idle angle on input reversal, seen as positioning drift on direction change; torsional stiffness is elastic deflection per unit torque, affecting tracking accuracy and oscillation settling.
Testing: backlash at 3% rated torque on reversal; stiffness as the slope of the 50% torque loading curve. The ZKRV series achieves <=1 arcmin backlash with ~30% higher stiffness than same-size cycloidal designs - why joint modules adopt it.
Sizing: pick the rating at 50% of load torque for life margin; for high-dynamics joints prioritise stiffness over ratio. ZKRV series parameter tables are on the product pages.
