Dual-rigid-body dynamic modeling and prototype-based validation of a 3-UPRP+UP parallel platform

A kinematic and dual-rigid-body dynamic framework is developed for a three-degree-of-freedom 3-UPRP+UP parallel platform. Structural offset and passive slider motion are embedded in closed-form limb constraints, yielding inverse and numerical forward kinematics, an actuator-rate Jacobian, and a stroke-constrained workspace. The Jacobian differs from central finite differences by at most 1.01 × 10 − 7 mm / rad , and actuator lengths differ from MSC Adams by at most 0.00484 mm. The DRB inverse-dynamics model separates the lower swing frame from the upper moving platform and retains the peripheral cylinder, rod, and slider bodies. Generalized-force RMSEs against MSC Adams are 0.0134 N ⋅ m , 0.0105 N ⋅ m and 2.76 × 10 − 5 N for roll, pitch, and relative heave; a single-rigid-body model raises the heave error to 102.59 N. A DRB-based computed-torque controller with preload-centered allocation is formulated, with nominal exponential stability and uniform ultimate boundedness under bounded disturbances. Co-simulation gives amplitude ratios of 0.9090, 0.9371, and 0.8483. Prototype tests are limited to geometric calibration, static pitch validation, and single-axis vertical-acceleration comparison. The static pitch and acceleration RMSEs are 0.0869 ∘ and 0.1647 m / s 2 , respectively, with an acceleration correlation coefficient of 0.8543. The full controller is evaluated only on the virtual prototype.