Adaptive linkage concept for replicating multi-phase stroke mechanics.

Abstract

Adaptive kayaking devices currently limit biomechanical fidelity, constraining range of motion and introducing unnatural dynamic profiles that impair user performance. This study proposes a four-bar linkage mechanism that replicates the natural semi-ellipsoidal and multi-phase forward stroke, grounded in biomechanics research and motion capture data. The stroke path was benchmarked against a standard derived from a prior kayak stroke analysis and refined using data characterizing movement across three spatial axes. A representative stroke profile was developed and implemented in a computer-aided design environment, with design optimization performed using engineering simulation tools. Two adaptive linkage models-one for high-performance use and one for recreational users-were validated by comparing their motion paths to the target profile. The high-performance model achieved a deviation of 22.0 mm; the recreational model achieved 79.7 mm. In contrast, a widely used commercial mount showed a deviation of 272.7 mm. This conceptual redesign addresses known biomechanical limitations, offering a scalable assistive solution with translational potential in rehabilitation and adaptive recreation.