Modern production systems have to allow high performance cutting processes in a flexible production system environment at a high level of accuracy. The final workpiece accuracy is mainly influenced by the thermo-elastic behavior of the machine tool and can be improved by additional measures, compensation strategies and an optimized machine design. These measures are often implemented as stand-alone solutions. According to the Industry 4.0 all information should be connected in a single model of the actual machine state to increase machining accuracy. It is therefore necessary to integrate upcoming smart fluid power systems into the machine network.

<div>Traction control (TC) systems have become quite common in on-road passenger vehicles in recent years. However, for vehicles in other applications, they are not as widely available.</div><div>This work presents a methodology for the proper design and implementation of a traction control system for heavy duty off-road machines, using a wheel loader as a reference vehicle.</div><div><br></div><div><div>A simulation model was developed, using standard vehicle dynamics constructs, including equations of motion and a description of the distribution of weight between the axles for different operating conditions. This model contains considerations for resistive forces acting on the machine implement, such as that generated by a work pile. The simulation also incorporates a detailed representation of the slip-friction characteristics between the vehicle tires and the road surface. One objective of this research was to model this interaction accurately, because the system traction behavior is dependent on it. Therefore, a series of tests was run using a state estimator to generate data on the slip-friction relationship at various ground conditions, and the results were incorporated into the simulation model. The dynamics of the machine braking system pressure were also modeled to give a more accurate description of the system response. The result is a mathematical model capable of accurately reproducing the behavior of the real-world system.</div></div><div><br></div><div><div>One of the primary goals of this work was the description of the traction control strategy itself, which should work as effectively and efficiently as possible. Several different aspects of the system were taken into consideration in generating this control structure. First, a relatively simple controller based on a PID control law was created. This controller was updated to account for peculiarities of the traction control system, as well as aspects like time delay. From there, more advanced controllers were created to address certain aspects of the system in greater detail. First, a self-tuning controller based on real-time optimization strategies was developed, to allow the controller to quickly adapt to changes in ground condition. Then, different nonlinear controllers were synthesized which were designed to address the theoretical behavior of the system. All of these controllers were simulated using the system model and then some were run in experiments to show their potential for improving system performance. To improve system efficiency, the machine drivetrain itself was also examined to develop a more efficient control algorithm. By designing a more efficient methodology, traction control congurations which had previously seen increases in fuel consumption of 16% were now able to actually reduce fuel usage by 2.6%.</div></div><div><br></div><div><div>Another main goal of this work was the development of a prototype system capable of implementing the formulated control strategies. The reference machine was modied so that the brakes could be controlled electronically and independently for implementation of the TC system. The vehicle was instrumented using a wide array of sensors, and estimation methodologies for accurately determining vehicle speed and implement forces were designed. The velocity estimator designed in this work is more accurate and more reliable than an industry standard sensor, which is important for traction control implementation. The implement force estimate was also quite accurate, achieving payload estimate errors of less than 2.5%, comparable to commercially-available measurement systems. This setup allowed for tests to be accurately compared, to assess the traction control performance.</div></div><div><br></div><div><div>With the objective of performing experiments on the traction control system, many tests were run to assess its capabilities in various situations. These tests included experiments for characterizing the vehicle behavior so that the simulation model could be updated to accurately reflect the physical machine performance. Another task for the experimental work was the generation of useful metrics for quantifying traction control performance. Laboratory experiments which were very controlled and repeatable were also run for generating data to improve the system model and for comparing traction control performance results side-byside. The test metrics proposed for these experiments provided for accurate, repeatable comparisons of pushing force, tire wear, and brake consumption. For each of these tests, the traction control system saw an increase in pushing force of at least 10% when compared with the stock machine, with certain operating conditions showing increases as high as 60%. Furthermore, every test case showed a decrease in wheel slip of at least 45% (up to 73% for some cases), which translates into increased tire longevity.</div></div><div><br></div><div><div>Other tests were conducted in the eld, designed to mimic the real-world operating conditions of the wheel loader. Various performance comparisons were made for different congurations in which traction control could provide potential benets. These included parameters for comparing overall vehicle performance in a typical truck loading cycle, such as tire wear, fuel consumption, and material moved per load. Initial results for this testing showed a positive result in terms of wheel slip reduction, but other performance parameters such as fuel consumption were negatively impacted. Therefore, the control structure was reexamined extensively and new methods were added to improve those results. The final control implementation saw a 12% reduction in tire slip, while also reducing fuel consumption by 2.6% compared to the stock system. These results show signicant potential for traction control as a technology for maximizing the performance output of construction machines.</div></div>

Modern production systems have to allow high performance cutting processes in a flexible production system environment at a high level of accuracy. The final workpiece accuracy is mainly influenced by the thermo-elastic behavior of the machine tool and can be improved by additional measures, compensation strategies and an optimized machine design. These measures are often implemented as stand-alone solutions. According to the Industry 4.0 all information should be connected in a single model of the actual machine state to increase machining accuracy. It is therefore necessary to integrate upcoming smart fluid power systems into the machine network.

<p>Hydraulic systems have many applications in the construction, transportation, and manufacturing sectors. Recent design trends involve systems with higher working pressures and more compact systems, which are advantageous because of power density increase. However, these trends imply higher forces and larger vibration amplitudes while having lesser mass and damping, leading to higher noise levels. Meanwhile, hydraulic machinery started prospecting new applications with tighter noise regulations, a trend which was also pushed by the electrification tendency in several fields of transportation and agriculture. One method to attain noise mitigation is passive-noise canceling techniques have the advantage of not introducing energy to the system. This approach arranges pressure ripple waves in a destructive pattern by projecting a hydraulic circuit's geometry, configuration, and features.</p> <p> </p> <p>This dissertation aims to predict fluid-borne noise sources and investigate passive noise-canceling solutions for multiple operations conditions targeting to impact many hydraulic systems and a broad range of operating conditions. Primarily a coupled system model strategy that includes a one-dimensional line finite element model is developed. The line model predicts pressure wave generation and propagation. The model features versatility since parameters like line diameter and material can be discretized node by node. Simulations are compared to measured data in a realistic novel hydraulic hybrid transmission for validation. </p> <p> </p> <p>Subsequently, an extensive numerical investigation is performed by setting fixed parameters along the hydraulic lines' length and comparing several isolated geometric properties in simulation. The developed line model is also used to study the influence of line features such as diameter and extent of the conduit. Cost-effective and simple passive solution solutions such as Quincke tubes (parallel lines), expansion chambers, and closed branches are selected and investigated on simulation. Four target pressure ripples are chosen as indicators for summarizing passive line elements behavior. The frequency-domain behavior of the pressure ripple peaks regarding the line's length is identified and isolated in simulation at the 50-5000Hz frequency spectrum. An experiment test rig is designed to implement these solutions and the experiments show three developed passive elements as practical and effective solutions for reducing fluid borne noise sources. The selected designs yielded noise source attenuation over most of the frequency spectrum measured with piezoelectric pressure variation sensors and accelerometers in different positions in the hydraulic circuit. Sound pressure measurements detected reductions over 3dB in the best cases. </p> <p> </p> <p>Also, a passive interference approach based on the principle of secondary source flow ripple cancellation was conceptualized, modeled, and implemented in a tandem axial-piston unit. The strategy consists of setting the phase between the two synchronous units to accomplish destructive interference in targeted unit harmonics. Two indexing strategies are investigated first analytically and then on simulation. One of the indexing strategies was implemented in a pre-existent commercial axial-piston tandem unit. Experiment results confirmed effectiveness for the first and third unit’s harmonics, where reductions over 15dB on pressure ripple were measured.</p> <p> </p> <p>Finally, a fluid-structure interaction based on the poison coupling principle is developed using the method of characteristics. Transfer functions of the pipeline accelerations versus the pressure ripples on lines calculated on simulation and later obtained experimentally to highlight ta critical vibration band from 2000Hz to 3000Hz with high acceleration response.</p> <p> </p><br>

<p dir="ltr">This research project aims to develop a robotic platform capable of drilling horizontal laterals from existing wellbores, offering data-guided steering and control features using information captured by sensors. The project provides an opportunity to expand the application of downhole drilling robots toward semi-autonomous operations in existing fields, especially those with declining production. Mature fields represent a global resource, and even modest hydrocarbon reserves additions are substantial to keep up the energy demand, having positive economic and environmental impacts. Available lateral drilling techniques do not fit the constraints offered by the challenge; moreover, they are not cost-effective.</p><p dir="ltr">The project will be organized into three phases to accomplish this developmental study. First, design criteria and key performance aspects will be identified and established to design a self-propelled robotic prototype capable of drilling lateral sections from an existing wellbore with an internal diameter of 4” to 6”. The creation of lateral sections can potentially add hydrocarbon reserves taking advantage of an already-drilled vertical section of a mature field. Second, the design of the prototype will take place, along with the design of a sub-surface communication and control system. The third phase is manufacturing and subsystems integration, finishing with a pilot test in a controlled environment. Based on the pilot testing results, design optimization will occur. Finally, a field version will be designed, and IP (Intellectual Property) disclosures and plans for commercialization will be identified and addressed.</p>

Technological advances (e.g., high speed communication, artificial intelligence) and affordable computing and sensor hardware have become a key driver of developments like “Industry 4.0” or the “Industrial Internet of Things” (IIoT). Large numbers of machines and products are equipped with sensors to constantly monitor their condition, log usage data or trigger control processes. IIoT has been largely adopted by OEMs in various industries (such as automotive, machinery industry, or healthcare and medical), turning their product into cyber-physical systems. However, the resulting potential is not yet accessible to component manufacturers. Overall, horizontal integration of the value chain is still in its infancy. Specifically, IIoT for fluid powers just started in recent years with first research projects and commercial solutions. This work presents a reference architecture for cyber-physical fluid power systems which depicts how horizontal integration can be achieved and which potentials thus can be released. The architecture is validated in an industrial use case. Furthermore, the paper at hand discusses which components of the architecture should be addressed by which actor in the fluid power ecosystem in order to leverage opportunities from the IIoT.

<p>Emission regulations and global policies to tackle climate change have forced industries and businesses to take measures to curb their impact on the environment. According to the United Nations Environment Program 2022 report on emissions [1], the transportation sector contributes to one-quarter of all energy-related CO2 emissions, and it is set to double by 2050. A recent report [2] suggests that off-road vehicles and equipment account for three-quarters of particulate matter and one-quarter of the nitrogen oxides emitted from mobile transportation sources in the US. The major challenge in decarbonizing or electrifying off-road machines is that they come in a wide range of sizes, weights, and functions, creating barriers to bringing down costs through economies of scale. Fluid power systems which are ubiquitous in these machines have been electrified in a compact and efficient manner to break even the costs of electrification. </p> <p>In off-road applications, where actuation systems heavily depend on hydraulics, there is a high demand for novel systems based on electric prime movers that can enable zero-carbon emission vehicles. An appropriate combination of electric prime movers and hydraulic machines commonly known as electrohydraulic units (EHUs) can help leverage the benefits of both these technologies. The integration of these two technologies in a single casing shaftless EHU can further maximize compactness and reduce cost. However, to achieve such an integrated EHU there is no standard procedure or recommended guidelines for equipment manufacturers owing to the interdisciplinary nature of the problem. </p> <p>This study proposes a generic design methodology to design electrohydraulic units (EHUs). As a starting point, a survey study was undertaken to compare different combinations of electric and hydraulic machines when designing an EHU. The different combinations were investigated for different operating drive cycles for their performance as well as other factors such as power-to-weight, cost, and the possibility of variable displacement. An axial piston machine (APM) was selected as a hydraulic machine (HM) to be integrated with a permanent magnet synchronous motor (PMSM) as the electric machine. </p> <p>The design methodology is demonstrated for an integrated electrohydraulic architecture with the APM housed inside the core of the PMSM. Such an architecture not only makes the overall integration much more compact but also allows for better thermal management of the EM. In such an architecture, the EM governs the overall power density of the integration and the total mass of the integration owing to inherent torque density differences. An EM design optimization is adopted for a predefined HM architecture to design the proposed EHU integration. The design optimization is used to quantify the effect of key EHU design specifications on the EM size and performance. EHU specifications such as sizing torque, operating voltage, aspect ratio, cooling efficacy, number of poles, and power-to-weight ratio have been studied to draw generic trends. These generic trends in the design specifications are used to outline clear guidelines on the impact of each of the EHU specifications for future EHU designers.</p> <p>Using the generic design trends, the design methodology is extended to size the EHU based on typical operating demands using the HM variable displacement, EM overload capability, and the EM flux weakening operation. These sizing studies allow the designers to size the EHU for the specific drive cycle operating demands and avoid oversizing the EHU. The EM flux weakening mode of operation allows the EM to be sized for a peak power level lower than the corner power of operation. The EM overload operation allows a reduction in the sustainable sizing torque lower than that of the maximum torque demand. The variable displacement in the HM can be used for improving overall EHU efficiency when selecting a low voltage or using a compact EM as well as to reduce the EM sizing torque. Two operation algorithms are proposed to define the EHU operation using variable displacement. Additionally, the sizing of a single EHU for multiple applications is also demonstrated. Such multi-utility EHU sizing can promote mass production and improve the rate of electrification in off-road machines.</p> <p>Finally, a prototype-tested EHU design based on the sizing study is demonstrated and the design considerations in such a design process are discussed. The prototype of the integrated EHU with a fixed displacement APM was able to reach the full capability of the reference APM. Thermal considerations are made on the EM sizing, to ensure the reliability of the designed EHU.  A novel self-sustained EHU architecture using the HM working fluid as a cooling fluid for the EM was designed. This was achieved by proposing a three-port valveplate design to divert part of the delivery stroke to cool the EM. A lumped parameter HM model was used to optimize this third port for an EHU prototype.</p>