Kinematic sensitivity, parameter identification and calibration of a non-fully symmetric parallel Delta robot

•Variational method to model sensitivity considering more error sources as possible.•A modified Delta robot is less sensitive to the geometric variations than its original counterpart.•Confirmed calibration method and parameter identification model by simulated calibration.•Parameter identification by minimizing square residuals between predicted and measure positions.•Robot absolute accuracy improved from 1.4mm to 0.1-0.13mm after calibration.