Efficiency improvement and evaluation of electric hydraulic excavator with speed and displacement variable pump

Research note: Machinery, manumission, and economic machinations

Review of hybrid electric systems for construction machinery

Powertrain electrification continues to be a growing trend in vehicular applications. Electric powertrains have numerous advantages over traditional mechanical and hydraulic powertrains but there are still important challenges to overcome for long-term commercial success. This research presents a technological assessment of present and future developments of powertrain electrification in non-road mobile machinery (NRMM). The challenges and opportunities of NRMM electrification are described in detail. The trends and drivers related to technological development such as regulations, policies and market development are analyzed, and technology enablers are highlighted. Future scenarios are formulated based on the prevailing trends and drivers, development of key components, scientific literature and status of the non-road mobile machinery industry. Some recommendations are also given in relation to the development of hybrid and electric powertrains for NRMM. The key findings of this research indicate that the electrification of NRMM is slowly started and the progress is demonstrated by hybridization of some specific, successful mobile machines. In short-term, high component and technology development costs remain the main barrier for higher adoption of electric and hybrid powertrains. In the long-term scenario, many NRMM can operate autonomously and powertrain electrification has become mainstream technology.

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Overview of Powertrain Electrification and Future Scenarios for Non-Road Mobile Machinery

During the virtual development and experimental testing of advanced construction machinery, automation approaches for automated task execution can prove very valuable In this paper, modeling and automation approaches for a hydraulic mini excavator are developed In particular, a physical model for detailed system analysis and a simplified Hammerstein model for controller tuning are developed and validated with measurement data from the mini excavator For attitude estimation of the excavator, inertial measurement units and extended Kalman filters are used in a sensor fusion framework The control concept for automation is based on a virtual driver consisting of a state machine for task coordination as well as offset-free model predictive controllers (MPCs) for decentralized and robust tracking control of all motion axes The constrained MPC optimization problems are solved in real time by means of the accelerated proximal gradient method Experimental results from the mini excavator prove the developed control approach to be valuable for virtual development and automated testing during the commissioning of hydraulic machinery Note to Practitioners —In this paper, a hydraulic mini excavator is considered for demonstrating the benefits of automation with regard to the development of advanced mobile machinery A detailed physical model and a simplified model are introduced for virtual analysis and comissioning of the excavator This allows for detailed system analysis even at an early development stage Then, a framework for automated testing of the real prototype is introduced This concept is based on attitude estimation filters, a state machine, and model predictive controllers and closely resembles the human driver in its behavior, but allows for reproducible testing results and therefore reduces commissioning efforts and development costs Particular attention is paid to the robustness of the control concept, since the coupling of the hydraulic axes and digging forces lead to disturbances that need to be compensated A simple, yet efficient and real-time capable algorithm is provided for numerical optimization Experimental results show that the developed methods can contribute to the automation of hydraulic machinery, and that the introduced framework can easily be extended in order to automate other types of machinery with simple hydraulics

Modeling and Offset-Free Model Predictive Control of a Hydraulic Mini Excavator

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

Recent demands to reduce pollutant emissions and improve energy efficiency have driven the implementation of hybrid solutions in mobile machinery. This paper presents the results of a numerical and experimental analysis conducted on a hydraulic hybrid excavator (HHE). The machinery under study is a middle size excavator, whose standard version was modified with the introduction of an energy recovery system (ERS). The proposed ERS layout was designed to recover the potential energy of the boom, using a hydraulic accumulator as a storage device. The recovered energy is utilized through the pilot pump of the machinery which operates as a motor, thus reducing the torque required from the internal combustion engine (ICE). The analysis reported in this paper validates the HHE model by comparing numerical and experimental data in terms of hydraulic and mechanical variables and fuel consumption. The mathematical model shows its capability to reproduce the realistic operating conditions of the realized prototype, tested on the field. A detailed energy analysis comparison between the standard and the hybrid excavator models was carried out to evaluate the energy flows along the system, showing advantages, weaknesses and possibilities to further improve the machinery efficiency. Finally, the fuel consumption estimated by the model and that measured during the experiments are presented to highlight the fuel saving percentages. The HHE model is an important starting point for the development of other energy saving solutions.

https://www.mdpi.com/1996-1073/9/12/1002/pdf

Hydraulic Hybrid Excavator—Mathematical Model Validation and Energy Analysis

Energy saving solutions for a hydraulic excavator

Modeling Simulation and Experimental Verification of an Excavator Hydraulic System - Load Sensing Flow Sharing Valve Model

This paper describes a mathematical modelling methodology developed for the rapid simulation of an excavator hydraulic system. The
modelling approach presented enables a reduction of the control system development time for a complete excavator, while providing accurate
system dynamics. A tool for defining an appropriate control strategy is a key point for satisfying the need for systems with better energy-efficiency.
Moreover, the model will be a significant support in investigating energy recovery solutions and evaluating the suitability of hybrid
solutions (mechanical/hydraulic/electric). The hydraulic model, composed of the pump’s grey box model and the valve block white box model,
has been validated on the basis of a set of experimental data collected on a test bench. The results of this study are presented in this paper.

Luca Riccò

Papers

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

Hydraulic Hybrid Excavator—Mathematical Model Validation and Energy Analysis

Energy saving solutions for a hydraulic excavator

Modeling Simulation and Experimental Verification of an Excavator Hydraulic System - Load Sensing Flow Sharing Valve Model

Simulation of an Excavator Hydraulic System Using Nonlinear Mathematical Models