Hybridization methodology based on DP algorithm for hydraulic mobile machinery — Application to a middle size excavator

• A methodology to compare different hydraulic hybrid system layouts is presented.
• The methodology takes advantage of the dynamic programming (DP) algorithm.
• Optimal hybrid layout configuration and its optimal control policies can be defined.

Fuel consumption and pollutant emission reduction are and will continue to be the most important drivers in the improvement of mobile machinery hydraulic system. Many different solutions and options are proposed in the literature to improve the machinery fuel efficiency, and many of these are based on hybrid solutions. The aim of this paper is to present a hybridization methodology which allows to compare different system layouts, to dimension the energy storage devices, to define the optimal control policies, and finally to determine the more effective hybrid system layout. The proposed methodology takes advantage of the dynamic programming (DP) algorithm. The machinery mathematical model and information about working cycle have to be known “a priori” in order to take advantage of the presented methodology.The hybridization methodology has been applied to a hydraulic excavator as a guideline example, and the results are reported in the last section of the paper.