Semi-analytical Approach to Trajectory Optimization for Stacker Cranes Regarding Energy Saving

TL;DR

This paper presents a semi-analytical method for optimizing stacker crane trajectories to minimize energy use and maximize recuperation, with potential applications in warehouse job scheduling.

Contribution

It introduces a systematic analytical approach for trajectory optimization considering energy flow, applicable to electrical machines with power-kinematics relations.

Findings

Optimal trajectories differ between energy consumption and recuperation phases.

The method is validated on a real stacker crane model.

Potential for improving warehouse efficiency through energy-aware scheduling.

Abstract

The aim of this study is to give insights into the trajectory optimization w.r.t. energy consumption and recuperation for stacker cranes in a high-bay warehouse. Based on an analytical necessary optimality condition, a targeted numerical implementation is set up to perform systematic computations of optimal trajectories which are further categorized. Particularly, the differences between energy consumption and recuperation as well as for up and down movements are pointed out. Although examined for a concrete, experimentally validated model of stacker cranes, the methodical approach could be adapted to other electrical machines possessing a power flow model, i.e. a functional relation between the kinematics (velocity, acceleration for instance) and the resultant power. In addition, boundaries of the velocity, the acceleration and the jerk are incorporated. Such a systematic analysis of energy optimal trajectories can be further used for improving the job scheduling in a warehouse.