Flexible Multibody Simulation Framework for a Single 6-RUS Leg for Space-Docking Applications

Space robotics increasingly relies on compliant manipulation for safe, low-impact docking under pose uncertainty. PACOMA is a 6-RUS (Revolute–Universal–Spherical) parallel continuum manipulator designed for low-impact docking. This thesis develops a control-oriented flexible multibody framework at the leg level, modeling a planar surrogate as a four-bar mechanism with two rigid links and one flexible Timoshenko beam. The beam is discretized via the finite element method and coupled to the rigid links through holonomic constraints, yielding differential-algebraic equations implemented in MATLAB and integrated with a generalized-α scheme. Two self-contained verification blocks support the framework: a compact rigid four-bar baseline and an isolated beam module. These are used for symbolic EOM checks and static/modal validations, as well as preliminary time-domain comparisons within a commercial multibody dynamics environment (MSC Adams). A leg-level rigid–flexible–rigid prototype is also assembled in MSC Adams to mirror the MATLAB formulation; quantitative cross-validation is deferred until the coupled model attains stable convergence. The resulting leg-level simulation pipeline exposes clear interfaces for state-space extraction and is structured for model-based control, with particular attention to LQR-type design in subsequent development. While comprehensive end-effector load cases and closed-loop tests on the coupled flexible model are reserved for future work, the thesis consolidates the modeling stack needed to scale from leg-level analysis to the full 6-RUS architecture. The framework aligns with PACOMA’s goals—safe interaction through compliant limbs and robustness to docking misalignment—and outlines a practical roadmap to complete flexible coupling and transition from simulation to control.