Robustness Analysis of an Electrohydraulic Steering Control System Based on the Estimated Uncertainty Model

The impossibility of replacing hydraulic drives with other type drives in heavy duty machinery is the main reason for the development of a system for controlling hydraulic power steering. Moreover, the need for remote automatic control of the steering in specific types of mobile machinery leads to significant scientific interest in the design of embedded systems for controlling electro-hydraulic steering units. This article introduces an approach, which has been developed by authors, for robust stability and robust performance analysis of two embedded systems for controlling electro-hydraulic power steering in mobile machinery. It is based on the suggested new more realistic “black box” SIMO model with output multiplicative uncertainty. The uncertainty is obtained by parameters confidence interval and Gauss approximation formula. The embedded control systems used a linear-quadratic Gaussian (LQG) controller and H∞ controller. The synthesis of the controllers was performed on the basis of a nominal part of an uncertainty model. Robust stability and robust performance analyses were performed in the framework of a so-called structured singular value, μ. The obtained theoretical results were experimentally approved by real experiments with both of the developed control systems, which were physically realized as a laboratory test rig.

Analysis of the influence of design parameters on the agro-ecological qualities of tractor tires

Experimental studies of the impact of agricultural mobile machinery movers on the soil are seasonal in nature and require complex experimental equipment. The complexity of the physical processes occurring in the elastic wheel-ground system requires the introduction of many assumptions and limitations that reduce the accuracy of the results, according to the design of simulation models performed in the software environment. The aim of the research was to study the influence of the design parameters of the tire on the efficiency of the normal deflection along the contact spot zone X. Studies have shown that 65% to 77% of the normal deflection of the tire is used when passing the contact spot. The reinforcement parameters of the tire frame have the greatest impact on the efficiency of the normal deflection along the contact spot zone. With an increase in the number of layers of the frame cord from 2 to 8, the coefficient of usability of the normal deviation for the stroke of the contact spot decreases from 0.761 to 0.689, with an increase in the angle of inclination of the frame cords - decreases from 0.755 to 0.693.

Towards a Standard Taxonomy for Levels of Automation in Heavy-Duty Mobile Machinery

Automated and autonomous systems change the nature of human interactions and their respective role within the systems. To characterize such changes, several domain specific levels of automation (LOA) taxonomies have been proposed over the years. The SAE J3016 levels for driving automation have been adopted as the de-facto standard in the automotive industry and the broader society. However, the heavy-duty mobile machinery (HDMM) industry does not have a commonly accepted LOA taxonomy, thereby relying on organizational specific LOA taxonomies adapted from SAE J3016. Moreover, HDMM handle and transport external materials in addition to driving tasks. Thus, SAE J3016 inadequately captures the manipulation operations of HDMM. This paper proposes a new LOA taxonomy for HDMM, to accommodate both, the manipulation and driving operations of HDMM. Building on the SAE J3016 taxonomy, the LOA in this paper is proposed as a two-dimensional 6 × 6 matrix, with machine manipulation operations on one dimension, and driving operations on the other. Thus, the LOA matrix could be generalized for HDMM in different application areas. The proposed LOA matrix could also serve as a guide and starting point for future standardized and collaborative discourse in HDMM research, development, and subsequent deployments.

AI-Based Condition Monitoring of Hydraulic Valves in Zonal Hydraulics Using Simulated Electric Motor Signals

Zonal hydraulics, in particular Direct Driven Hydraulics (DDH), is an emerging transmission and actuation technique that is proposed to be used for electrification of heavy-duty mobile machinery. In addition to the already demonstrated advantages of DDH, which include high efficiency, compactness, and ease of maintenance, it is also capable of condition monitoring. The condition monitoring features can be obtained through indirect analysis of the existing electric motor signals (voltage and current) using artificial intelligence-based algorithms rather than by adding extra sensors, which are normally required for conventional realization. In this paper, the valve condition monitoring method of the DDH through electrical motor signals is explored at an early development stage. Firstly, the hydraulic valve models, which involve the valve fault behaviors, are added to the basic DDH model. Secondly, healthy and faulty scenarios for the valves are simulated, and the data are generated. Thirdly, the preliminary artificial intelligence-based condition monitoring classifier is developed using the simulation data, including feature extraction, algorithm training, testing, and comparison of accuracy. The effects of modeling error on developing the condition monitoring function are analyzed. In conclusion, the preliminary outcomes for the valve condition monitoring of the DDH are achieved by taking advantage of modeling and simulation and by utilizing the existing electric motor signals.

Analysis of emissions and fuel consumption from forklifts by location of operation

The share of road transport accounts for more than 85% of the total structure of freight transportation. In this process, mainly motor vehicles are used to carry out the freight work. In addition to them, forklifts are also used, whose task is to load and unload goods. These vehicles are categorized as NRMM (Non-Road Mobile Machinery). Forklift trucks have internal combustion or electric drive. The paper presents an analysis of the emission of pollutants and fuel consumption from forklift trucks equipped with diesel and LPG power. The study uses the author's test taking into account the raising/lowering of a pallet, a loaded and unloaded run. The measurements were made in the warehouse and outside the warehouse using the Porstable Emission Measurement System (PEMS) equipment. The aim was to show the influence of loading conditions on the emission of pollutants and fuel consumption.