Uncertainty, Sensitivity, and Efficiency Analysis of a Hybrid Piezoelectric–Electromagnetic Energy Harvester

Digitalization and emerging technologies are increasing the demand for wireless sensing and the Internet of Things (IoT), which provide opportunities for autonomous sources of electricity in the form of energy harvesting systems. This paper focuses on the challenges in hybrid piezoelectric-electromagnetic kinetic energy harvesting systems that deliver output power at milliwatt levels, sufficient for current IoT electronics. The main task in the employment of energy harvesting technology for industrial applications is transitioning from laboratory test samples to industrial-scale prototype deployment, with emphasis on sensitivity and uncertainty analyses of energy harvesting parameters. This paper analyses this problem using a single-degree-of-freedom model for a hybrid piezoelectric-electromagnetic kinetic energy harvester, where the effect of uncertainty in design and material input parameters on harvested power outputs is examined. Industrial application uncertainties, including manufacturing and geometric tolerances, uncertainties in material parameters, and fluctuations in ambient input parameters, are assessed and analyzed using the Saltelli method. Key findings highlight the amplification of uncertainties, with mechanical damping identified as the most influential parameter of harvested power. By investigating piezoelectric and electromagnetic coupling factors, this study provides actionable insights for optimizing hybrid energy harvesters and adjusting coupling parameters for maximal output power generation.