Hydraulic Actuator Research Articles

An innovative experimental device for characterizing the responses of monopiles subjected to complex lateral loading

Offshore wind turbines are usually founded on monopiles. During the operation period, the structure is subjected to complex lateral loading from wind, wave and current. The soils surrounding those monopiles may deform with increasing the number of loading cycles, leading to tilting of the whole structure; hence, it is vital to carry out physical model tests to examine the long-term performance of monopiles. This study proposes an innovative experimental setup for centrifuge modelling of the response of monopiles under complex lateral loading. Hydraulic actuators are adopted to apply lateral loads on model pile, and electrohydraulic servo-valves and associated controllers are used to achieve a closed loop position or load control. A carefully designed spherical hinge and load bars are used to connect the model pile and actuator shafts. This enables that the pile can rotate freely and can move vertically freely. A centrifuge test on a winged monopole subjected to perpendicular lateral loading was carried out at 100g. The experimental results shed light on pile responses in the cyclic loading and constant loading directions.

A Hydraulic Haptic Actuator for Simulation of Cardiac Catheters.

This article presents a haptic actuator made of silicone rubber to provide both passive and active haptic forces for catheter simulations. The haptic actuator has a torus outer shape with an ellipse-shaped inside chamber which is actuated by hydraulic pressure. Expansion of the chamber by providing positive pressure can squeeze the inside passage to resist the catheter traveling through. Further expansion can hold and push back the catheter in the axial direction to render active haptic forces. The size of the catheter passage is increased by providing negative pressure to the chamber, allowing various diameters of the actual medical catheters to be used and exchanged during the simulation. The diameter of the catheter passage can be enlarged up to 1.6 times to allow 5 to 7 Fr (1 Fr = 1/3 mm) medical catheters to pass through. Experiment results show that the proposed haptic actuator can render 0 to 2.0 N passive feedback force, and a maximum of 2.0 N active feedback force, sufficient for the cardiac catheter simulation. The haptic actuator can render the commanded force profile with 0.10 N RMS (root-mean-squares) and 10.51% L2-norm relative errors.

Design and Control of an Untethered Robotic Tuna Based on a Hydraulic Soft Actuator

Design and Control of an Untethered Robotic Tuna Based on a Hydraulic Soft Actuator

Pressure control of clutch hydraulic actuator in automotive transmission based on time-frequency domain combined approach

Pressure control of clutch hydraulic actuator in automotive transmission based on time-frequency domain combined approach

Soft Wearable Body-Powered Hydraulic Actuation System for a Prosthetic Finger Design.

Finger and fingertip loss is the most common form of upper-limb amputation. With a focus on amputations involving the loss of distal and/or partial middle finger segments, this paper outlines the design and development of a novel soft body-powered hydraulically-driven actuation system for a prosthetic finger, while offering an in-depth examination of its subsystems. The proposed device utilises a soft wearable hydraulic mechanism to transfer pressure from the proximal interphalangeal (PIP) joint of the human finger to the distal interphalangeal (DIP) joint of the prosthetic finger, enabling movement of the soft prosthetic DIP joint. The design parameters of the soft actuator, such as its configuration, constituent material, and volume were analysed through experiments with able-bodied participants. Each participant tried 42 different actuators while flexing their index finger, repeating the task four times, yielding 168 trials per participant. The human and prosthetic finger flexion angles and resultant pressures were measured using an Aurora electromagnetic sensor and a fluid pressure transducer. All data was segmented and analysed. Soft actuator designs were selected through statistical analysis of the material (Agilus 30 and Dragon Skin 30), configuration (chambers located underside or around the PIP joint), and volume. The study demonstrated that the selected soft wearable hydraulic mechanism transferred generated pressure from the participant's PIP joint effectively, enabling movement of the prosthetic digit. Our research contributes to current developments in versatile body-powered prosthetic devices, laying the foundations for broad applications in affordable healthcare devices.

Digital Twin-based Predictive Maintenance for Sheet Metal Bending

This paper focuses on the implementation of predictive maintenance processes using both physics-based and data-driven methods, specifically applied to a Salvagnini panel bender. The primary objective is to enhance production data analysis through digital twin predictions, enabling the calculation of process parameters that cannot be directly measured. Two key aspects are addressed in this study: Firstly, two global measures of the effective cumulative load on a machine during its lifetime are formulated. These measures can be used as criteria for estimating the health condition of a machine and for comparing different machines. To achieve this, dimensionless parameters are derived from actual production data. Secondly, a remaining useful life (RUL) model is developed for two machine components relying on production data analysis and digital twin predictions. The first component under consideration is a hybrid hydraulic actuator. Internal leakage prediction for this component is performed based on its data history, resulting in a corresponding trend curve. Additionally, wear of critical bearings is calculated using an analytical model that depends on the production history log. Through the proposed hybrid approach, this paper aims to enhance the predictive maintenance process by leveraging both physics-based and data-driven methodologies. The findings from this study can offer valuable insights for optimizing maintenance strategies and improving the overall efficiency of similar manufacturing systems.

Rendering Fine Tactile Feedback With a Novel Hydraulic Actuation Method for Wearable Haptic Devices

Rendering Fine Tactile Feedback With a Novel Hydraulic Actuation Method for Wearable Haptic Devices

Non-linear PI control of a Ladle Furnace

This work aims to control the hydraulic actuator in the Ladle Furnace of ACINOX Las Tunas. This system has an asymmetric behavior according to the upward or downward movement of the electrodes. Several controllers were tuning for evaluation of the relevance of electrode weight variation, among them a novel non-linear PI controller of guaranteed robustness. The use of a non-linear function could be evaluated to compensate for the asymmetric behavior of the process being reached excellent results with regard to the case in where a symmetric function was used.

Vibration-polynomial-based optimal trajectory planning for mobile concrete pumping equipment with state constraints

To improve the operating stabilities of the flexible hydraulic manipulator in concrete pumping equipment, a trajectory planning method based on optimal vibration energy is presented. First, predefined trajectories are generated by the quintic polynomial method, and kinematic inversions are established by unifying the velocity and angle constraints into the velocity level. Then, relationships between the boom vibration and the vibration energy are solved in modal space. Specifically, hydraulic actuators are regarded as spring-damping systems to calculate generalized forces into the vibration equation. The vibration equation can solve the modal coordinate and vibration model function, such that the elastic potential energy to cause vibration is completely described. Next, floating values are captured by a genetic algorithm to minimize vibration energy, and then introduced to the predefined trajectory to weaken the boom vibration. Last, the proposed trajectory planning method is verified by a concrete pumping spreader with a 13 m hydraulic manipulator.

Study on Shield Machine Technology

The shield machine is a specialized construction equipment used for excavating tunnels, particularly in underground construction projects. The shield machine plays a pivotal role in modern engineering and construction, minimizing surface disruption and environmental impact. Shield machines can adapt to different geological conditions and project requirements, and efficiently excavate tunnels in various ground conditions, reducing construction time and costs. Shield machines improve worker safety by reducing risks associated with manual tunneling, and digging tunnels with high precision, crucial for projects like subways. In essence, shield machines are essential tools in modern tunnel construction, offering efficiency, safety, and precision in building underground infrastructure for various purposes, including transportation, utilities, and more. This paper summarizes the development history of the shield machine and its basic structure, discusses its limitations and challenges, and makes a certain analysis of the application of the shield machine while discussing the innovations and methods of the hydraulic propulsion mechanism of the shield machine. This paper may offer a reference for the development of shield machine.

The potential of using 3D printing in the manufacture of mini hydraulic systems

The work is devoted to an analytical engineering study of the practicality of using 3D printing for the manufacture of hydraulic components, in order to solve the problems associated with weight, size and complexity inherent in traditional hydraulic elements. The research aims to demonstrate the feasibility of using 3D printing to achieve simplified design and increased efficiency. The work presents samples of hydraulic elements printed on a 3D printer, which reflects the practical feasibility of this approach. A simple and practical design methodology is proposed for two key components of a typical hydraulic system, namely, a hydraulic cylinder and a directional servo-valve, which allows hydraulic actuators to be controlled using any programmable microcontroller. A distinctive feature of this approach is the emphasis on the principles of compact design, which facilitates the integration of many parts into single, multifunctional part. In addition, the use of lightweight materials in 3D printing helps reduce the overall weight of hydraulic components. The proposed method also allows the integration of various hydraulic elements into a single integral structure printed on a 3D printer, offering a pragmatic solution to the size and complexity issues associated with traditional metal hydraulic systems. The scope of this innovative approach extends to the creation of prototypes of hydraulic and pneumatic robots, as well as devices that require compactness, precision and adaptability. This methodology is promising for implementation in the field of robotics, especially for tasks where space and weight constraints are critical factors.

Optimization design and experiment study on a water hydraulic flexible actuator integrating flexible inner skeleton and soft external skin used for underwater flexible gripper

A water hydraulic flexible gripper with three flexible actuators is proposed, which integrates a soft external skin and a flexible inner skeleton to enhance resistance against water pressure. To investigate the deformation characteristics of the water hydraulic flexible actuator, a mathematical model is established to describe the relationship between water pressure and actuator deformation. The effects of different materials, structural sizes, and inlet pressure are analyzed through simulation. A Kriging model is utilized to fit the simulation results, while a multi-island genetic algorithm is employed to obtain an optimal solution for the structure of the flexible actuator. Finally, the deformation of the flexible actuator under various inlet pressures is quantified through experimental measurements, and the obtained results exhibit degree of consistency with the simulation outcomes. After completing static experiments at a simulated sea depth of 1000 m, the tip forces of flexible actuators were tested, and then land and underwater grasping experiments were conducted. The water-hydraulic flexible actuator developed in this study has great potential for handling fragile or deformable objects during deep-sea. This promotes the application of water-hydraulic flexible manipulators in the field of underwater robotics, providing higher flexibility and adaptability compared to traditional rigid manipulators.

Trajectory Tracking Control of a Skid-Steer Mobile Robot Based on Nonlinear Model Predictive Control with a Hydraulic Motor Velocity Mapping

In this study, we address the trajectory tracking control problem of a hydraulic-driven skid-steer mobile robot. A hierarchical control strategy is proposed to simultaneously consider the robot’s position control and the velocity control of the hydraulic motors. At the upper level, a nonlinear model predictive control (NMPC) method is employed to control the position and heading of the mobile robot. The NMPC controller takes into account the robot’s physical constraints and generates the desired robot motion velocity. Then, to control the hydraulic drive system, a current–velocity mapping-based control method is introduced. By establishing the mapping relationship between the control current applied to the hydraulic motor and its corresponding output velocity, the dynamics of the hydraulic motors are characterized. Consequently, the lower-level controller can directly obtain the control signal for the hydraulic actuator through lookup mappings. Additionally, PID controllers are adopted to compensate for velocity tracking errors. The proposed hierarchical control strategy decouples the robot’s position control and the hydraulic system control, simplifying the overall controller design, leading to improved control performance. To validate the effectiveness of the proposed control strategy, several experiments were conducted on a hydraulic-driven skid-steer mobile robot, and the results demonstrate the effectiveness of the proposed approach.

Electrical-hydraulic Modeling and Simulation in MATLAB/Simulink of an Industrial Multi-service Vehicle for Tunneling

The land transport sector has gone through multiple phases of evolution in vehicle design, development, and manufacturing. In particular, the construction sector continues to move towards autonomous vehicles, which have been one of the major trends and have become a hot topic in the industrial and academic world. With this new technology of assistance systems, which control the hydraulic actuators of a car (steering wheel, accelerator, and brake), humans are freed from driving tasks and the number of traffic accidents will be reduced. The modeling and simulation phases play a major role in the development of the construction machine in order to simulate the dynamic behavior of the vehicle and adjust all the parameters beforehand, so that the automated functionality will be easy to realize, and safety will be improved with high accuracy. The objective of this paper is to design a hydro-electric industrial vehicle model for the company METALLIANCE using MATLAB/Simulink environment and compare its simulation with experimental tests. The study addresses the modeling of industrial machines based on the mathematical description of the vehicle dynamics by defining for real-time evaluation of the different vehicle parameters, verifying, and validating the simulation model by comparison with real recorded data.

An Interpretable Digital Twin for Self-Aware Industrial Machines.

This paper presents a proposed three-step methodology designed to enhance the performance and efficiency of industrial systems by integrating Digital Twins with particle swarm optimization (PSO) algorithms while prioritizing interpretability. Digital Twins are becoming increasingly prevalent due to their capability to offer a comprehensive virtual representation of physical systems, thus facilitating detailed simulations and optimizations. Concurrently, PSO has demonstrated its effectiveness for real-time parameter estimation, especially in identifying both standard and unknown components that influence the dynamics of a system. Our methodology, as exemplified through DC Motor and Hydraulic Actuator simulations, underscores the potential of Digital Twins to augment the self-awareness of industrial machines. The results indicate that our approach can proficiently optimize system parameters in real-time and unveil previously unknown components, thereby enhancing the adaptive capacities of the Digital Twin. While the reliance on accurate data to develop Digital Twin models is a notable consideration, the proposed methodology serves as a promising framework for advancing the efficiency of industrial applications. It further extends its relevance to fault detection and system control. Central to our approach is the emphasis on interpretability, ensuring a more transparent understanding and effective usability of such systems.

Constrained Motion Control of an Electro- Hydraulic Actuator Under Multiple Time-Varying Constraints

The motion control technology of electro-hydraulic actuators has great significance in industrial applications. Constraints significantly limit the motion control performance of actuator motion control, in addition to the inherent nonlinearities and uncertainties of the electro-hydraulic systems. The constraints comprise kinematic and dynamic constraints, and they can be time-varying owing to variations in the system. If the constraints are not fulfilled, the control accuracy may be adversely affected, for instance by actuator vibration, cavitation, or even instability. This study proposes a constrained motion control strategy for a variable-speed pump-driven hydraulic actuator. To robustly track a desired trajectory under constraints, the control strategy combines a nonlinear filter-type trajectory planning strategy and an adaptive robust motion controller. The trajectory planning strategy is designed by considering dynamic and kinematic constraints of the electro-hydraulic system, and it synthesizes a trajectory that reaches the given reference in minimum time while fulfilling these multiple constraints. Meanwhile, the adaptive robust motion controller tracks the synthesized trajectory with guaranteed control accuracy in the presence of inherent nonlinearities of the electro-hydraulic actuator. In addition, the assignments of the multiple constraints are adjusted in real time, which further optimize the constrained motion control performance. Comparative experiments with various given references were conducted to verify the advantages of the proposed constrained control strategy.

Energy analysis of a hybrid electro-hydraulic system for efficient mobile hydraulics

Energy efficiency plays a significant role in mobile hydraulics due to the high amount of carbon dioxide and pollutants being released into the atmosphere. Efficiency improvements are urgently needed, so the electrification of mobile hydraulics represents a fantastic opportunity in this regard. This approach leads to electro-hydraulic systems that remove functional flow throttling in control valves and enable energy recovery. Fuels savings were already demonstrated in simulation, but the literature does not offer entire energy analyses of these electro-hydraulic solutions. This limitation prevents complete system-level comprehension and does not give enough insight to pinpoint areas for further efficiency improvements. Thus, this paper focuses on a hybrid system for excavators based on electro-hydraulic drives that is compared against the original valve-controlled layout. The objective is to quantify the energy flows insight the excavator during relevant operations and highlight the resulting energy losses. The outcomes confirm that electro-hydraulic solutions are suitable for a low-carbon economy. They indicate hydraulic actuators, speed-controlled pumps, and electric motors as the critical components for further energy efficiency enhancement excluding the combustion engine.

Automation of an African wooden pestle: pneumatic or hydraulic actuation?

Automation of an African wooden pestle: pneumatic or hydraulic actuation?

Experimental benchmark control problem for multi-axial real-time hybrid simulation

Advancing RTHS methods to readily handle multi-dimensional problems has great potential for enabling more advanced testing and synergistically using existing laboratory facilities that have the capacity for such experimentation. However, the high internal coupling between hydraulics actuators and the nonlinear kinematics escalates the complexity of actuator control and boundary condition tracking. To enable researchers in the RTHS community to develop and compare advanced control algorithms, this paper proposes a benchmark control problem for a multi-axial real-time hybrid simulation (maRTHS) and presents its definition and implementation on a steel frame excited by seismic loads at the base. The benchmark problem enables the development and validation of control techniques for tracking both translation and rotation degrees of freedom of a plant that consists of a steel frame, two hydraulic actuators, and a steel coupler with high stiffness that couples the axial displacements of the hydraulic actuators resulting in the required motion of the frame node. In this investigation, the different components of this benchmark were developed, tested, and a set of maRTHS were conducted to demonstrate its feasibility in order to provide a realistic virtual platform. To offer flexibility in the control design process, experimental data for identification purposes, finite element models for the reference structure, numerical, and physical substructure, and plant models with model uncertainties are provided. Also, a sample example of an RTHS design based on a linear quadratic Gaussian controller is included as part of a computational code package, which facilitates the exploration of the tradeoff between robustness and performance of tracking control designs. The goals of this benchmark are to: extend existing control or develop new control techniques; provide a computational tool for investigation of the challenging aspects of maRTHS; encourage a transition to multiple actuator RTHS scenarios; and make available a challenging problem for new researchers to investigate maRTHS approaches. We believe that this benchmark problem will encourage the advancing of the next-generation of controllers for more realistic RTHS methods.

Comparison of hydraulic, pneumatic and electric linear actuation systems

Different applications or industries use different systems for linear actuation, such as hydraulic, pneumatic or electric. Electric systems are becoming increasingly popular and are already replacing hydraulic systems in various applications. These are known to be potentially harmful to the environment, as large amounts of fluid can be released into the environment in the event of a pipe burst or other accident. This paper presents the results of a comparison between hydraulic, pneumatic and electric systems under variable conditions but with similar loads in all three systems. The common feature of all three systems is the input power, which was limited to 1.1 kW. There was no hydraulic accumulator in the hydraulic system and no pressure vessel in the pneumatic system, so no stored energy could influence the system behaviour or results. The main difference between the systems studied was the profile of displacement and power consumption. The most consistent response and lowest power consumption were obtained with the electric system, although both hydraulic and pneumatic systems can achieve consistent response with some modifications.