Title: Research on gravity potential energy echelon recovery and speed control of industrial vehicle

Authors: Guang Xia; Yongcheng Pan; Xiwen Tang; Yang Zhang; Shaojie Wang

Addresses: Institute of Automotive Engineering, Hefei University of Technology, Hefei, 230009, China ' School of Automotive and Traffic Engineering, Hefei University of Technology, Hefei, 230009, China ' College of Electronic Engineering, National University of Defense Technology, Hefei, 230027, China ' School of Automotive and Traffic Engineering, Hefei University of Technology, Hefei, 230009, China ' Institute of Automotive Engineering, Hefei University of Technology, Hefei, 230009, China

Abstract: This paper proposes an innovative echelon recovery scheme to address inefficiencies in conventional forklift operations, particularly the dissipation of gravitational potential energy during frequent lifting and lowering cycles. The hydraulic oil circuit, with throttling control mechanisms impacting temperature and lubrication, contributes to reduced engine efficiency. The solution involves three load-specific accumulators with predetermined initial pre-inflation pressure and volume. Dynamic models are established for the lifting cylinder, accumulator, fork, and solenoid valve. Using a model predictive control (MPC)-based hierarchical strategy, the upper decision-making layer selects the target accumulator for energy recovery, while the lower predictive control layer utilises MPC to govern fork descent speed. Simulation and experimental results demonstrate a notable 40% enhancement in energy recovery efficiency compared to traditional hydraulic systems. The hierarchical control strategy effectively limits fork descent speed fluctuation to around 10%, significantly improving both gravitational potential energy recovery rates and operational smoothness in forklift fork functionality.

Keywords: fork gravity potential energy echelon recovery; accumulator precharge pressure; MPC; model predictive control; fork falling speed control.

DOI: 10.1504/IJVD.2024.143979

International Journal of Vehicle Design, 2024 Vol.96 No.2, pp.130 - 169

Received: 20 Dec 2023
Accepted: 19 Oct 2024
Published online: 16 Jan 2025 *

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