Showing papers on "Hydraulic machinery published in 2018"
TL;DR: This paper incorporates the dynamics of a hydraulic actuator that is used to create the required active suspension forces into the controller design, and an approximation-free control method is introduced that leads to reduced computational burden and complexity and is more suited for practical applications.
Abstract: This paper presents a novel control strategy for nonlinear uncertain vehicle active suspension systems without using any function approximators [eg, neural networks (NNs) or fuzzy logic systems (FLSs)] Unlike previous results that neglect the effect of actuator dynamics, this paper incorporates the dynamics of a hydraulic actuator that is used to create the required active suspension forces into the controller design To address the nonlinearities of this hydraulic system, an approximation-free control method is introduced In this method, the widely used NNs and FLSs are not needed This leads to reduced computational burden and complexity, and thus, it is more suited for practical applications Moreover, by introducing a prescribed performance function and the associated error transform, the proposed controller can guarantee both the transient and steady-state suspension responses The stability of the closed-loop system and the suspension performance requirements are rigorously proved Finally, comparative simulations are conducted to validate the improved performance and robustness of the proposed method
123 citations
03 Aug 2018
TL;DR: The main achievements of the AEGART (EU CleanSky Project) project is described in the key areas, including electric machines, power electronic converters, thermal management, and overall system control design.
Abstract: More-electric aircraft (MEA) has become a dominant trend for modern aircraft. On-board MEA, many functions, which are conventionally driven by pneumatic and hydraulic power, are replaced with electrical subsystems. Starting aircraft engines with an electric motor instead of using pneumatic power from the auxiliary power unit is one of the major characteristics of future aircraft. This paper presents the development of a novel electric starter–generator system for aircraft applications. This paper describes the main achievements of the AEGART (EU CleanSky Project) project in the key areas, including electric machines, power electronic converters, thermal management, and overall system control design. The developed prototype has been tested successfully, and the test results are presented in this paper.
87 citations
TL;DR: In this paper, an integrated drive and energy recuperation system based on a three-chamber hydraulic cylinder is proposed, where one chamber of the three chamber cylinder is directly connected to a hydraulic accumulator, storing and reusing the potential energy of the boom.
66 citations
TL;DR: In this paper, the authors proposed a hydraulic-pneumatic hybrid powertrain for heavy duty vehicles that need to transpose both highway and urban areas, where braking energy is recovered by a hydraulic system and stored in a hydraulic accumulator and in an air reservoir.
62 citations
TL;DR: An extended-state-observer (ESO)-based nonlinear adaptive control scheme for the motion tracking control of the hydraulic valve-controlled single-rod actuator system and the effectiveness of the proposed method is verified through extensive comparative experiments.
Abstract: Hydraulic servomechanism is the typical mechanical/hydraulic double-dynamics coupling system with heavy nonlinearity, parametric uncertainties, and mismatching uncertainties input problems. How to estimate and compensate mismatching uncertainties by observer is a very important issue. This paper proposes an extended-state-observer (ESO)-based nonlinear adaptive control scheme for the motion tracking control of the hydraulic valve-controlled single-rod actuator system. This paper provides a solution to estimate and compensate the mismatching disturbances, i.e., the mechanical dynamics uncertainties. With the developed method, both the hydraulic dynamics uncertainties and the mechanical dynamics uncertainties can be estimated and compensated effectively. Moreover, the parameters adaptive mechanism is also supplemented with ESO to further improve the tracking performance. The parametric uncertainties, modeling, and unknown external disturbances are comprehensively addressed. In theory, the asymptotic tracking can be achieved even in the presence of unknown external constant disturbances and parametric uncertainties. Besides giving the theoretical results and proof, the effectiveness of the proposed method is verified through extensive comparative experiments.
56 citations
TL;DR: In this article, the authors investigate hydraulic regime in the middle part of Loire River located in France and find that significant variability characterizes natural streams in space and time that describe hydraulic regime of the entire stream.
Abstract: Significant variability characterizes natural streams in space and time that describe hydraulic regime of the entire stream. In this paper, the importance of investigation and assessment of hydraulic system in the context of management of surface water resources is discussed. The objective of this study is to investigate hydraulic regime in the middle part of Loire River located in France. Loire River basin is the largest river basin in France and origin of many potential flood events. Investigation of a hydraulic regime of the Loire River is conducted using traditional hydraulic simulation model HEC-RAS. Hydraulic modeling of the river is carried out by considering two different datasets (i.e. flood and low flow events). A certain number of hydraulic structures, which have the significant effect on the hydraulic regime of the river, is considered as well. Through Froude number computation, it is noticed that middle part of the Loire River demonstrates subcritical regime. Accurate calibration and validation of the model are performed by changing Manning coefficient along the riverbed. Computation carried out for both data sets; show that there are no big differences between observed and simulated water levels, results obtained are satisfactory. Therefore, to get more accurate information about the hydraulic regime at the middle part at of Loire River, the further simulation needs to be done by considering an additional dataset of floods and low flow events.
51 citations
TL;DR: In this paper, experimental, theoretical and numerical data on stream water wheels were systematically collected from literature and analyzed, focusing especially on wheel dimensions, supporting structures, blades and speed, and more light on their hydraulic behavior was shed, adopting the previous classification for a better explanation and understanding.
50 citations
TL;DR: In this paper, a cost effective stainless steel machine is investigated in pump and turbine operation and established conversion methods are used for predicting the best efficiency point of the turbine, but experimental investigations are still indispensable for a determination of complete Q-H-characteristics.
49 citations
TL;DR: The results show that the hydraulic cylinders can move smoothly along the expected trajectory under the premise of low energy consumption, and the operate velocity fluctuation is small and the positioning error to the target position is about 1 mm.
44 citations
01 Oct 2018
TL;DR: The paper introduces the details of the WLR, highlighting the innovative design and optimization of physical construction which is considered to maximize the mobile abilities, enhance the environmental adaptability and improve the reliability of hydraulic system.
Abstract: Wheel-legged hybrid robot with multi-modal locomotion can efficiently adapt to different terrain environments, as well as realize rapid maneuver on flat ground. We have developed a novel hydraulic wheel-legged robot (WLR) combined with a humanoid structural design. This robot can assist to emergency scenarios where the high mobility, adaptability and robustness are required. The paper introduces the details of the WLR, highlighting the innovative design and optimization of physical construction which is considered to maximize the mobile abilities, enhance the environmental adaptability and improve the reliability of hydraulic system. Firstly, maximizing the mobile abilities includes optimizing the configuration of each actuator and integrating them with the structure, so as to achieve a large range of movement and also reduce the mass and inertia of the legs. Secondly, the environmental adaptability can be ensured with a magnetorheological (MR) fluid-based damper and direct-drive wheels. Thirdly, improving the reliability of hydraulic system involves using the selective laser melting (SLM) technology to integrate hydraulic system and reducing the number of exposed tubes. The maneuverability of the WLR is demonstrated with a series of experiments. At present, the WLR can perform the following operations, including moving on the flat ground, squatting, and picking up a heavy load.
44 citations
TL;DR: The results showed that the proposed decoupling compensation method for damping improvement of the electrohydraulic control system with multiple actuators reduced velocity and pressure oscillations under different working conditions, so the dynamic performance is improved for the multiactuator system.
Abstract: This paper proposes a decoupling compensation method for damping improvement of the electrohydraulic control system with multiple actuators. The low damping property of hydraulic systems has been a remarkably troublesome issue for a few decades. Previously, this issue with one actuator has been addressed effectively by state feedback and signal compensation, e.g., dynamic pressure feedback. However, the poor damping with multiple actuators is still intractable and pendent due to the complex coupling effect of different loads. A decoupling compensator based on pump/valve combined control is proposed for a typical electrohydraulic system with multiple actuators for mobile machinery. Using decoupling control of different load branches, the coupling hydraulic circuit with multiple cylinders is transformed into multiple separate single-cylinder circuits with dynamic compensation. The dynamic characteristics of different actuators are then improved synchronously without mutual interference, while the steady performance remains the same without loss of controllability. Compound motion tests on a 2-ton hydraulic excavator were carried out. The results showed that the proposed compensator reduced velocity and pressure oscillations under different working conditions, so the dynamic performance is improved for the multiactuator system.
TL;DR: In this article, a survey of recent advancements and upcoming trends in motion control technologies employed in designing multi-actuator hydraulic systems for mobile machineries is presented, including open-center and load sensing controls.
Abstract: This paper presents a survey of recent advancements and upcoming trends in motion control technologies employed in designing multi-actuator hydraulic systems for mobile machineries. Hydraulic systems have been extensively used in mobile machineries due to their superior power density and robustness. However, motion control technologies of multi-actuator hydraulic systems have faced increasing challenges due to stringent emission regulations. In this study, an overview of the evolution of existing throttling control technologies is presented, including open-center and load sensing controls. Recent advancements in energy-saving hydraulic technologies, such as individual metering, displacement, and hybrid controls, are briefly summarized. The impact of energy-saving hydraulic technologies on dynamic performance and control solutions are also discussed. Then, the advanced operation methods of multi-actuator mobile machineries are reviewed, including coordinated and haptic controls. Finally, challenges and opportunities of advanced motion control technologies are presented by providing an overall consideration of energy efficiency, controllability, cost, reliability, and other aspects.
TL;DR: This work showcases the development and results of a model-predictive controller (MPC) for a marine active-heave compensation (AHC) system and suggests that the MPC-PI controller is able to decouple up to 99.6% of the transmitted motion.
TL;DR: The kinematic description and mathematical dynamic model of a three-degrees-of-freedom manipulator, including hydraulic actuator dynamics, and a disturbance observer-based robust control scheme for the position and torque tracking control subjected to the external disturbances and parameter uncertainties are given.
Abstract: This paper gives the kinematic description and mathematical dynamic model of a three-degrees-of-freedom manipulator, including hydraulic actuator dynamics, and then proposes a disturbance observer-based robust control scheme for the position and torque tracking control subjected to the external disturbances and parameter uncertainties. First of all, the kinematic of the manipulator system is built according to the Denavit–Hartenberg notation. The joint space, actuator space, and the mathematical model of the manipulator, including hydraulic actuator dynamics, are then presented. Next, a robust control technique is designed for the fast and finite-time tracking capability of the torque signals along the desired torque commands, and a fast nonsingular terminal sliding mode control algorithm is developed to guarantee the fast convergence of the joint positions to their desired values. Moreover, two disturbance observer schemes are proposed to estimate and compensate the external disturbances and modeling errors in the manipulator system and hydraulic actuator system. Stability analysis of the cascade hydraulic manipulator system is analyzed and proved using the backstepping technique and Lyapunov theory. Finally, numerical simulations are obtained to validate the effectiveness of the designed control algorithm.
TL;DR: Through numerical and experimental studies, it is demonstrated that with the proposed control algorithm, the dynamic characteristics of the HSV is not only greatly improved but adapted to pressure changes, and the variation range of the dynamic performance can be controlled within 7.4% under 4–20 MPa operating conditions.
TL;DR: In this article, an optimal design method for the pressure control valve considering stability is proposed to ensure a stable and fast response performance of the clutch actuator system, which is based on the motion of the valve spool and coupling fluid dynamics in the system.
TL;DR: In this article, a two-raft-type wave energy converter (WEC) consisting of two rafts and a hydraulic power take-off (PTO) unit is considered, and a combined model based on the linear wave theory and basic-hydraulic equations is presented.
TL;DR: In this article, the coordinated control problem that occurs when HHMAS operates in the auxiliary drive mode is addressed; the solution to this problem is the key to the maximization of HHMAS.
TL;DR: A model is developed for the synchronous brush drive of an airfield sweeper equipped with a throttle flow divider that is not of gate-valve type, and employs a plunger-type control system.
Abstract: A model is developed for the synchronous brush drive of an airfield sweeper. This machine is equipped with a throttle flow divider that is not of gate-valve type, and employs a plunger-type control system. Methods are proposed for improving the static and dynamic properties of the synchronized system.
TL;DR: A novel model, considering the coupling relationship of the penstock (hydraulic system), the power grid (electrical system) and the guide vane device (mechanical system), offers a useful insight into the vibration diagnosis of hydropower stations.
TL;DR: The main design tradeoffs that should be handled when developing oil-hydraulic Power Take-Off devices aiming at the maximization of energy extraction from waves with a point absorber wave energy converter are presented.
TL;DR: In this article, a flywheel of variable moment of inertia (due to inflow or outflow of hydraulic fluid) and a variable displacement pump/motor are used to control the pressure in the hydraulic system.
TL;DR: In this article, a soft hydraulic actuator is presented which uses elastic energy storage for the purpose of pulsed-jet propulsion of soft unmanned underwater vehicles, inspired by the swimming of squids and octopuses.
Abstract: A soft hydraulic actuator is presented which uses elastic energy storage for the purpose of pulsed-jet propulsion of soft unmanned underwater vehicles. The actuator consists of a flexible membrane that can be inflated using a micropump and whose elastic potential energy may be released on demand using a controllable valve, in a manner inspired by the swimming of squids and octopuses. It is shown that for equivalent initial elastic energy, the drop in peak thrust is linearly proportional to the decrease in nozzle cross section. Peak hydraulic power amplification of the soft actuator of approximately 75% is achieved with respect to that of the driving pump, confirming that passive elasticity can be exploited in aquatic propulsion to replicate the explosive motion skills of agile sea-dwelling creatures.
TL;DR: The challenges facing the PHC technology, which prevented it from becoming widely spread in the market, are focused on and the countermeasures are discussed.
TL;DR: Simulation and experiment results showed that the proposed controller has a good transient-response and provides accurate position tracking in the presence of parametric uncertainties, uncertain nonlinearities, and external disturbances.
Abstract: This paper focuses on high-performance motion control of the electro-hydraulic system of hydraulic presses. A detailed mathematical model of the system was constructed. An electro-hydraulic system of hydraulic presses is a kind of nonlinear system with parametric uncertainties, uncertain nonlinearities, and external disturbances. To attenuate the above effects, a nonlinear robust motion controller based on an extended disturbance observer was developed. The outer position tracking loop was designed with a sliding mode control to compensate for disturbance estimation error, while the inner pressure control loop using the backstepping method can realize accurate output force control. The stability of the overall closed-loop system based on the Lyapunov approach can be proven to be effective. Both simulation and experiment results showed that the proposed controller has a good transient-response and provides accurate position tracking in the presence of parametric uncertainties, uncertain nonlinearities, and external disturbances.
TL;DR: Experiments show that the designed controller for the hydraulic system could control the engine rotating speed effectively, and ensure adequate hydraulic power for the robot, and the hardware and the software designs of the controller are demonstrated.
TL;DR: A multi-physics graphical model-based fault detection and isolation (FDI) method for doubly fed induction generator-based wind turbines using hybrid bond-graph theory is developed and demonstrated by the simulation results.
Abstract: Early detection and isolation of faults in wind power generators increases the availability of wind turbines and reduces their down times and maintenance costs. Wind turbines constitute a complex system that includes sub-systems from different physical domains such as electrical, mechanical, and hydraulic systems. They constitute hybrid dynamical systems comprising discrete parts due to presence of power electronic switches and continuous parts such as induction machines, pitch actuator and mechanical drive-train. In this paper, a multi-physics graphical model-based fault detection and isolation (FDI) method is developed for doubly fed induction generator-based wind turbines. The model of the wind turbine is developed using hybrid bond-graph theory that captures causal, temporal, and structural properties of the system. Causality inversion method is then employed to derive analytical redundancy relations (ARRs) based on the developed model. The FDI is performed based on the changes in the values of ARRs. A systematic approach based on Chi-square criterion is developed to determine the values of thresholds, based on which the change in ARRs due to occurrence of faults are detected. The capability of the proposed method in accurate and fast detection and identification of mechanical, electrical, and hydraulic faults is demonstrated by the simulation results.
TL;DR: In this paper, a discussion for challenges in model-based nonlinear control, latest developments and brief perspectives of hydraulic servo systems are presented: Modelling uncertainty in hydraulic system is a major challenge, which includes parametric uncertainty and time-varying disturbance.
Abstract: Hydraulic servo system plays a significant role in industries, and usually acts as a core point in control and power transmission. Although linear theory-based control methods have been well established, advanced controller design methods for hydraulic servo system to achieve high performance is still an unending pursuit along with the development of modern industry. Essential nonlinearity is a unique feature and makes model-based nonlinear control more attractive, due to benefit from prior knowledge of the servo valve controlled hydraulic system. In this paper, a discussion for challenges in model-based nonlinear control, latest developments and brief perspectives of hydraulic servo systems are presented: Modelling uncertainty in hydraulic system is a major challenge, which includes parametric uncertainty and time-varying disturbance; some specific requirements also arise ad hoc difficulties such as nonlinear friction during low velocity tracking, severe disturbance, periodic disturbance, etc.; to handle various challenges, nonlinear solutions including parameter adaptation, nonlinear robust control, state and disturbance observation, backstepping design and so on, are proposed and integrated, theoretical analysis and lots of applications reveal their powerful capability to solve pertinent problems; and at the end, some perspectives and associated research topics (measurement noise, constraints, inner valve dynamics, input nonlinearity, etc.) in nonlinear hydraulic servo control are briefly explored and discussed.
TL;DR: A new model that eliminates some of the limitations of existing models by predicting output force as a function of initial actuator geometry only and capturing the nonlinear variation in elastomer wall thickness as the actuator is strained is developed.
Abstract: McKibben actuators, comprised of an elastomeric tube wrapped in inextensible fibers, were developed in the 1950s and have been used primarily in pneumatic applications. Mc-Kibben actuators provide superior force and power density at a lower cost compared to many conventional actuators due to their simple design. This paper explores driving McKibben actuators with high-pressure hydraulics and reflects on some challenges associated with modeling the actuators at hydraulic pressures. Twelve actuators were designed, fabricated, and tested experimentally over a range of contraction ratios. Four modeling approaches were evaluated against experimental data including a new model that eliminates some of the limitations of existing models by predicting output force as a function of initial actuator geometry only and capturing the nonlinear variation in elastomer wall thickness as the actuator is strained. The experimental results suggest that the existing McKibben force models presented in this paper are not as accurate as the new model for tracking total axial force generation. The absolute value of the error from experimental values of each of the four models ranged from 9.1% for the new model developed in this paper to 9.9%, 10.0%, and 10.5% for the three other existing approaches, but the new model has unique advantages in modeling hydraulic McKibben actuators that require thicker tube walls. This study lays the ground work for future research in modeling soft robots comprised of compliant actuators powered hydraulically at high pressures.