Direct Actuation Research Articles

Biomimetic Soft Robotic Jellyfish for Lentic Ecosystem Monitoring

Environmental monitoring of lentic ecosystems is well suited for swarm robotics applications since they can operate autonomously and cover large regions. For such a task, a locomotion mechanism is necessary for traversal. Due to the challenging nature of underwater environments, researchers often draw inspiration from nature to improve robot mechanical performance. A box jellyfish in a good inspiration due to their efficient jet propulsion. Soft and smart materials are helpful in mimicking their propulsion because they can perform flexible and complex movement. Shape memory alloy (SMA) springs have been used for this purpose, but their slow actuation rate is a well-known disadvantage. This project aims to improve cycle rate and thus swim speed by implementing a bistable spring configuration into a soft robotic jellyfish. The bistable mechanism stores energy slowly in the expansion of the elastic silicone bell, then releases it suddenly in a contraction which propels the robot forwards with a higher force than would be possible with direct SMA actuation. Additionally, the antagonistic arrangement of SMA springs reset each other and produce the same outward expansion on both up and down stroke, improving cycles speeds by removing the need for a dedicated reset stroke which is typically required before using the springs again. Also, increasing the number of spring pairs does not interfere with the actuation, meaning cycle rates can be further improved by cycling which pair of springs is active. The proof-of-concept device operates at a frequency of 0.4 Hz, and produces enough thrust while tethered to swim through a tank. Future work involves performing fluid visualization tests to validate a simple mathematical model of flow through the bell, as well as optimize the design, integrate onboard environment sensors and implement autonomy to allow operation in a larger swarm.

Magnetically responsive manipulation of droplets and bubbles

AbstractDroplets and bubbles have a wide range of applications in industry, agriculture, and daily life, and their controllable manipulation is of significant scientific and technological importance. Versatile magnetically responsive manipulation strategies have been developed to achieve precise control over droplets and bubbles. To manipulate nonmagnetic droplets or bubbles with magnetic fields, the presence of magnetic medium is indispensable. Magnetic additives can be added to the surface or interior of droplets and bubbles, allowing for on‐demand manipulation by direct magnetic actuation. Alternatively, magnetically responsive elastomer substrates can be used to actuate droplets and bubbles by controlling the deformation of microstructures on the substrates through magnetic stimulation. Another strategy is based on untethered magnetic devices, which enables free mobility, facilitating versatile manipulation of droplets and bubbles in a flexible manner. This paper reviews the advances in magnetically responsive manipulation strategies from the perspective of droplets and bubbles. An overview of the different classes of magnetic medium, along with their respective corresponding droplet/bubble manipulation methods and principles, is first introduced. Then, the applications of droplet/bubble manipulation in biomedicine, microchemistry, and other fields are presented. Finally, the remaining challenges and future opportunities related to regulating droplet/bubble behavior using magnetic fields are discussed.

Directional actuation and phase transition-like behavior in anisotropic networks of responsive microfibers.

Two-dimensional shape-morphing networks are common in biological systems and have garnered attention due to their nontrivial physical properties that emanate from their cellular nature. Here, we present the fabrication and characterization of anisotropic shape-morphing networks composed of thermoresponsive polymeric microfibers. By strategically positioning fibers with varying responses, we construct networks that exhibit directional actuation. The individual segments within the network display either a linear extension or buckling upon swelling, depending on their radius and length, and the transition between these morphing behaviors resembles Landau's second-order phase transition. The microscale variations in morphing behaviors are translated into observable macroscopic effects, wherein regions undergoing linear expansion retain their shape upon swelling, whereas buckled regions demonstrate negative compressibility and shrink. Manipulating the macroscale morphing by adjusting the properties of the fibrous microsegments offers a means to modulate and program morphing with mesoscale precision and unlocks novel opportunities for developing programmable microscale soft robotics and actuators.

Abstract 14705: Diastolic Function is Uniquely Augmented by Direct Mechanical Ventricular Actuation in the Failing Heart

Introduction: Diastolic dysfunction represents a significant pathophysiology in cardiomyopathies and heart failure (HF), yet limited therapies exist for treatment. Direct Mechanical Ventricular Actuation (DMVA) is a non-blood contacting device highly unique in its ability to provide both diastolic and systolic support. The purpose of this study was to further evaluate DMVA’s effect on diastolic function in the failing heart. Methods: Adult canine (63.7 ± 13.4 lb, n=9) underwent repeated cycles of ventricular fibrillation to generate progressive levels of acute HF. DMVA was applied to support HF after defibrillation. Intracardiac echocardiography was used to quantify LV longitudinal strain/strain rates using speckle-tracking algorithms. Strain/strain rate peak magnitudes and composite waveforms were analyzed during baseline (n = 35), DMVA (n = 127), and non-support HF (n = 127). One-way ANOVA with post-hoc Tukey’s HSD was used to assess statistical differences (p<0.05) for all comparisons. Results: LV strain metrics were augmented during DMVA support (strain: 20.0 ± 0.5 %, strain rate: systolic, -1.64 ± 0.03 1/s, diastolic, 1.68 ± 0.04 1/s) versus non-supported HF (strain: 9.9 ± 0.2 %, p<0.001, strain rate: systolic, -0.83 ± 0.02 1/s, p<0.001, diastolic, 0.86 ± 0.02 1/s, p<0.001). All strain metrics were increased during DMVA compared to baseline (strain: 14.2 ± 0.4 %, p<0.001, strain rate: systolic, -1.11 ± 0.03 1/s, p<0.001, diastolic, 1.14 ± 0.04 1/s, p<0.001). Composite strain waveforms aligned by systolic peak revealed an early diastolic boost during DMVA relative to baseline (see figure). Conclusions: Diastolic strain dynamics were significantly improved during DMVA in this model of progressive HF. Direct cardiac compression devices can impair diastolic function, which limits feasibility for circulatory support. This study further validates that DMVA restores near physiologic LV strain patterns during HF and uniquely augments diastolic function.

Abstract 15552: Augmentation of Right Ventricular Strain Dynamics During Direct Mechanical Ventricular Actuation

Introduction: Available forms of mechanical circulatory support are associated with significant complications related to blood contact. Direct cardiac compression (DCC) devices avoid blood contact but may impair diastolic function. This derogatory effect of DCC devices may be related to a negative impact on RV function. Direct mechanical ventricular actuation (DMVA) uniquely augments LV diastolic function. The purpose of this study was to evaluate DMVA’s effect on RV function. Methods: Ischemic heart failure (HF) was induced using 5 mins of ventricular fibrillation (VF) circulatory arrest in large mature canines (n=9). Hearts were defibrillated and DMVA applied for 15 mins. VF circulatory arrest was subsequently re-induced for 5 mins to generate progressive HF. The experimental protocol was continued for 3 hrs. Intracardiac echocardiography was used to quantify longitudinal strain and peak strain rates in the RV and LV using speckle-tracking algorithms. Two-way ANOVA with Tukey HSD tests were used to evaluate statistical differences in strain metrics (baseline vs. HF vs. DMVA support and LV vs. RV). Results: DMVA increased RV fractional area change (DMVA: 0.282 ± 0.011, Mean ± SEM) relative to either baseline (0.221 ± 0.15, p=0.004) or HF (0.170 ± 0.006, p<0.001). DMVA statistically significantly augmented all RV strain metrics relative to either baseline or HF (Table). Additionally, all DMVA strain metrics were statistically significantly greater in the RV than the LV (LV strain: 18.8 ± 0.5 %, p<0.001, LV strain rate: systolic, -1.46 ± 0.04 1/s, p<0.001, diastolic, 1.51 ± 0.04 1/s, p<0.001). Conclusions: DMVA substantially improved RV strain dynamics compared to baseline or HF in this model. During DMVA support, strain dynamics in the RV were amplified more than the LV. This RV augmentation is important to achieving balanced biventricular DMVA support. Enhanced diastolic RV and LV augmentation during DMVA remains highly unique when compared to any other devices.

Integral passivity‐based control of underactuated mechanical systems with actuator dynamics and constant disturbances

AbstractThis work investigates the energy shaping control of a class of underactuated mechanical systems with first‐order actuator dynamics and subject to both matched and unmatched constant additive disturbances. To this end, a new nonlinear control law which includes two independent integral actions is presented. The controller design is outlined for systems with first‐order actuator dynamics, and also for systems with direct actuation. The effectiveness of the proposed approach is demonstrated with numerical simulations on an inertia wheel pendulum and on a ball‐on‐beam system, both actuated by electric DC motors and subject to constant disturbances.

MAIN ELECTRICAL COMPONENTS OF AN ASSAULT RIFLE WITH ADAPTIVE MECHANISM

This paper presents the design, simulation, and experimental validation of a bistable direct current actuator and its electronic control system. Regarding the working principle, the bistable linear actuator is like an electromagnet with two air gaps. The difference between the newly proposed linear actuator and a classical electromagnet is the usage of two Nd-Fe-B permanent magnets to maintain the mobile core in two holding positions. Also, a specially designed electronic control system was developed. This paper aims to explain the actuator’s working principle and its novel electronic control system advantages. This equipment is used in an assault rifle to limit the self-initiation of the cartridge due to barrel heating without the operator pulling the weapon’s trigger. The proposed bistable direct current actuator ensures a short time switching between its two holding positions. The electronic controller measures the temperature of the weapon's barrel with a thermocouple and applies a voltage on the coils to switch between the two holding positions of the actuator. The actuator was developed and analyzed using the FEMM package, and the mechanical parameters were computed with MATLAB. The electronic driver was developed with PCB design software, and the working principle was validated with a circuit analysis program.

Asymmetric electrodes for droplet directional actuation by a square wave on an open surface

The large-scale electrowetting-on-dielectric (EWOD) digital microfluidic platforms always require complex electrode-addressing schemes and high-cost fabrication methods of dielectric and hydrophobic layers. Hence, the voltage polarity-dependent electrowetting was used to actuate droplets with asymmetric printed circuit board (PCB) electrodes on an open slippery liquid-infused porous surface (SLIPS) chip. The V-shaped, convex-shaped, and curve-shaped coplanar asymmetric electrode arrays were designed to achieve the directional motion of a droplet by a square wave voltage signal. The operation ranges of voltage amplitude and frequency for continuously actuating a 10 µl droplet were obtained on the three asymmetric electrode arrays. Our results found that the curve-shaped electrode array has a broader voltage operation range than the other two for continuous pumping of a 10 µl droplet. It is because the droplet has a long effective width of contact line with the front curve-shaped electrode and does not overlap with the rear electrode during the movement. Meanwhile, a reconfigurable convex-shaped electrode structure was also proposed to achieve bidirectional actuation of a droplet by controlling the square wave voltage. This work provides a low-cost, straightforward electrode-addressing scheme for designing digital microfluidic devices.

Flexible Needle Steering with Tethered and Untethered Actuation: Current States, Targeting Errors, Challenges and Opportunities

Accurate needle targeting is critical for many clinical procedures, such as transcutaneous biopsy or radiofrequency ablation of tumors. However, targeting errors may arise, limiting the widespread adoption of these procedures. Advances in flexible needle (FN) steering are emerging to mitigate these errors. This review summarizes the state-of-the-art developments of FNs and addresses possible targeting errors that can be overcome with steering actuation techniques. FN steering techniques can be classified as passive and active. Passive steering directly results from the needle-tissue interaction forces, whereas active steering requires additional forces to be applied at the needle tip, which enhances needle steerability. Therefore, the corresponding targeting errors of most passive FNs and active FNs are between 1 and 2mm, and less than 1mm, respectively. However, the diameters of active FNs range from 1.42 to 12mm, which is larger than the passive steering needle varying from 0.5 to 1.4mm. Therefore, the development of active FNs is an area of active research. These active FNs can be steered using tethered internal direct actuation or untethered external actuation. Examples of tethered internal direct actuation include tendon-driven, longitudinal segment transmission and concentric tube transmission. Tendon-driven FNs have various structures, and longitudinal segment transmission needles could be adapted to reduce tissue damage. Additionally, concentric tube needles have immediate advantages and clinical applications in natural orifice surgery. Magnetic actuation enables active FN steering with untethered external actuation and facilitates miniaturization. The challenges faced in the fabrication, sensing, and actuation methods of FN are analyzed. Finally, bio-inspired FNs may offer solutions to address the challenges faced in FN active steering mechanisms.

Robotic Locomotion and Piezo1 Activity Controlled with Novel Liquid Marble‐based Soft Actuators

AbstractA novel soft actuator is designed, fabricated, and optimized for applied use in soft robotics and biomedical applications. The soft actuator is powered by the expansion and contraction of a graphene‐containing and encased liquid marble using the photothermal effect. Unfortunately, conventional liquid marbles are found to be too fragile and prone to cracking and failure for such applications. After experimentation, it is possible to remedy this problem by synthesizing liquid marbles encased with polymeric shells–polymerized in situ–for added mechanical strength and robustness. These marbles are shown to have intrinsic photothermal activity. They are then situated in bimorph‐type soft actuators where one side of the actuator has a dramatically different Young's modulus than the other, leading to directional actuation which is successfully demonstrated in multistep walking soft robots. The soft actuators are shown to successfully activate the mechanosensitive Piezo protein in a transfected human cell line with high effectiveness and no toxicity. Overall, the liquid marble‐powered soft actuators described here represent a new soft actuation methodology and a novel tool for mechanobiological studies, such as stem cell fate and organoid differentiation.

Precisely Navigated Biobot Swarms of Bacteria Magnetospirillum magneticum for Water Decontamination.

Hybrid biological robots (biobots) prepared from living cells are at the forefront of micro-/nanomotor research due to their biocompatibility and versatility toward multiple applications. However, their precise maneuverability is essential for practical applications. Magnetotactic bacteria are hybrid biobots that produce magnetosome magnetite crystals, which are more stable than synthesized magnetite and can orient along the direction of earth's magnetic field. Herein, we used Magnetospirillum magneticum strain AMB-1 (M. magneticum AMB-1) for the effective removal of chlorpyrifos (an organophosphate pesticide) in various aqueous solutions by naturally binding with organic matter. Precision control of M. magneticum AMB-1 was achieved by applying a magnetic field. Under a programed clockwise magnetic field, M. magneticum AMB-1 exhibit swarm behavior and move in a circular direction. Consequently, we foresee that M. magneticum AMB-1 can be applied in various environments to remove and retrieve pollutants by directional control magnetic actuation.

Biotissue‐Inspired Anisotropic Carbon Fiber Composite Hydrogels for Logic Gates, Integrated Soft Actuators, and Sensors with Ultra‐High Sensitivity

AbstractNatural biotissues like muscles, ligaments, and nerves have highly aligned structures, which play critical roles in directional signal transport, sensing, and actuation. Inspired by anisotropic biotissues, composite hydrogels with outstanding mechanical properties and conductivity are developed by compositing thermo‐responsive poly (N‐isopropylacrylamide) (PNIPAM) hydrogels with highly aligned carbon fibers (CFs). The anisotropic hydrogels show superior tensile strength (3.0 ± 0.3), modulus (74 ± 7.0 MPa), excellent electrical conductivity (≈670 S m−1), and ultra‐high sensitivity (gauge factor up to 647) along CFs, with an anisotropic ratio (AR) up to 740 over those in perpendicular direction. The extremely high AR in conductivity (more than 400) produces high‐level output in parallel direction and low‐level output in perpendicular direction with a direct current (DC) power supply, which is used to fabricate AND and OR gates. Moreover, the composite hydrogels are converted into thermo‐responsive actuators with CFs twisted before compositing with PNIPAM/clay network. The pre‐twisted CF helices impart internal stress that drives reversible actuation of hydrogel helices upon thermo‐stimulating. The actuation is self‐sensed due to the extremely high sensitivity of the composite hydrogels. Such biomimetic anisotropic self‐sensing hydrogel actuators resemble natural biotissues with both actuation and sensing capabilities, and have promise applications for artificial robotics.

A Novel Magnetic Transmission for Powerful Miniature Surgical Robots

Untethered magnetically actuated robots present significant advantages for biomedical applications by allowing power to be delivered wirelessly to remote, miniature robots through flesh and bone. Nevertheless, generating enough usable force to interact with their environment remains a challenge: Most millimeter-size magnetic robots achieve forces of much less than 0.1 N, which limits their medical applications. Therefore, a compact, millimeter-scale transmission is needed to amplify the output force. A novel microtransmission system is presented, composed of a driving magnet suspended between two twisted string actuators. An analytical model of the transmission is formulated to predict its behavior under both fixed load and fixed displacement configurations. Experimental measurements are used to validate the predicted maximum achievable force, to quantify the transmission performance over numerous cycles, to determine the effect of different string materials, and to determine the impact of hysteresis and viscoelasticity. Finally, the transmission is integrated into a 3 mm diameter surgical gripper prototype to demonstrate its effectiveness. With only a modest 20 mT of applied magnetic field, the gripper generates 1.09 N gripping force—a factor of 35 improvement in mechanical advantage and a factor of 62 improvement in gripping force compared to a similar size gripper using direct magnetic actuation. This microtransmission for miniature magnetic robots will enable high-strength untethered robots for minimally invasive surgical applications.

Direct and remote induced actuation in artificial muscles based on electrospun fiber networks

The present work reports a new configuration of soft artificial muscle based on a web of metal covered nylon 6/6 micrometric fibers attached to a thin polydimethylsiloxane (PDMS) film. The preparation process is simple and implies the attachment of metalized fiber networks to a PDMS sheet substrate while heating and applying compression. The resulting composite is versatile and can be cut in different shapes as a function of the application sought. When an electric current passes through the metallic web, heat is produced, leading to local dilatation and to subsequent controlled deformation. Because of this, the artificial muscle displays a fast and ample movement (maximum displacement of 0.8 cm) when applying a relatively low voltage (2.2 V), a consequence of the contrast between the thermal expanse coefficients of the PDMS substrate and of the web-like electrode. It was shown that the electrical current producing this effect can originate from both direct electric contacts, and untethered configurations i.e. radio frequency induced. Usually, for thermal activated actuators the heating is produced by using metallic films or conductive carbon-based materials, while here a fast heating/cooling process is obtained by using microfiber-based heaters. This new approach for untethered devices is an interesting path to follow, opening a wide range of applications were autonomous actuation and remote transfer of energy are needed.

Dynamic control of octahedral rotation in perovskites by defect engineering

Engineering oxygen octahedra rotation patterns in $ABO_3$ perovskites is a powerful route to design functional materials. Here we propose a strategy that exploits point defects that create local electric dipoles and couple to the oxygen sublattice, enabling direct actuation on the rotational degrees of freedom. This approach, which relies on substituting an $A$ site with a smaller ion, paves a way to couple dynamically octahedra rotations to external electric fields. A common antisite defect, $\mathrm{Al_{La}}$ in rhombohedral LaAlO$_3$ is taken as a prototype to validate the idea, with atomistic density functional theory calculations supported with an effective lattice model to simulate the dynamics of switching of the local rotational degrees of freedom to long distances. Our simulations provide an insight of the main parameters that govern the operation of the proposed mechanism, and allow to define guidelines for screening other systems where this approach could be used for tuning the properties of the host material.

A Review of Reinforcement Learning Applications to Control of Heating, Ventilation and Air Conditioning Systems

Reinforcement learning has emerged as a potentially disruptive technology for control and optimization of HVAC systems. A reinforcement learning agent takes actions, which can be direct HVAC actuator commands or setpoints for control loops in building automation systems. The actions are taken to optimize one or more targets, such as indoor air quality, energy consumption and energy cost. The agent receives feedback from the HVAC systems to quantify how well these targets have been achieved. The feedback is captured by a reward function designed by the developer of the reinforcement learning agent. A few reviews have focused on the reward aspect of reinforcement learning applications for HVAC. However, there is a lack of reviews that assess how the actions of the reinforcement learning agent have been formulated, and how this impacts the possibilities to achieve various optimization targets in single zone or multi-zone buildings. The aim of this review is to identify the action formulations in the literature and to assess how the choice of formulation impacts the level of abstraction at which the HVAC systems are considered. Our methodology involves a search string in the Web of Science database and a list of selection criteria applied to each article in the search results. For each selected article, a three-tier categorization of the selected articles has been performed. Firstly, the applicability of the approach to buildings with one or more zones is considered. Secondly, the articles are categorized by the type of action taken by the agent, such as a binary, discrete or continuous action. Thirdly, the articles are categorized by the aspects of the indoor environment being controlled, namely temperature, humidity or air quality. The main result of the review is this three-tier categorization that reveals the community’s emphasis on specific HVAC applications, as well as the readiness to interface the reinforcement learning solutions to HVAC systems. The article concludes with a discussion of trends in the field as well as challenges that require further research.

Physics-based modeling of homogeneous charge compression ignition engines with exhaust throttling

Homogeneous charge compression ignition (HCCI) engines create a more efficient power source for either stationary power generators or automotive applications. Due to the absence of direct actuation of ignition, HCCI based combustion control is quite challenging. For the purpose of control synthesis and design, a crank-angle based dynamic model of an HCCI engine with internal exhaust gas recirculation (EGR) is proposed in this paper. The HCCI autoignition timing is controlled by the amount of internal EGR induced by the cost effective exhaust throttling strategy. The zero dimensional single zone model is developed based on conservation of mass and energy and ideal gas law. The model is comprised of five subsystems: cylinder volume, intake, and exhaust runners along with combustion and heat-transfer models. Inputs to the model include engine speed, intake temperature, fueling rate, intake, and exhaust throttle positions. Outputs of the model contain the pressure, temperature, mass and burned gas fraction in the intake, exhaust and cylinder, air-to-fuel ratio (AFR), heat release rate, combustion phasing, and the indicated mean effective pressure (IMEP). The model is developed based on MATLAB/Simulink and validated against experimental data under steady-state and transient conditions at various intake temperatures, fueling levels, and exhaust throttle positions. Results demonstrate that by changing the exhaust throttle position, the pressure in the exhaust runner is regulated. As a result, the residual gas fraction is altered, leading to changes in mixture temperature and thus control of the HCCI combustion phasing. In the end, closed loop simulation is conducted with a linear quadratic Gaussian (LQG) controller applied to the crank-angle based model for regulation of combustion timing CA50 using exhaust throttle during load (fueling level) changes. In the future, this model can be utilized for control development and hardware in the loop (HIL) simulation.

Piston-Driven Pneumatically-Actuated Soft Robots: Modeling and Backstepping Control

Actuators’ dynamics have been so far mostly neglected when devising feedback controllers for continuum soft robots since the problem under the direct actuation hypothesis is already quite hard to solve. Directly considering actuation would have made the challenge too complex. However, these effects are, in practice, far from being negligible. The present work focuses on model-based control of piston-driven pneumatically-actuated soft robots. We propose a model of the relationship between the robot’s state, the acting fluidic pressure, and the piston dynamics, which is agnostic to the chosen model for the soft system dynamics. We show that backstepping is applicable even if the feedback coupling of the outer on the inner subsystem is not linear. Thus, we introduce a general model-based control strategy based on backstepping for soft robots actuated by fluidic drive. As an example, we derive a specialized version for a robot with piecewise constant curvature.

Bioinspired Nanostructured Superwetting Thin-Films in a Self-supported form Enabled “Miniature Umbrella” for Weather Monitoring and Water Rescue

HighlightsAn elastic, superhydrophobic and conductive thin film inspired by the natural self-supported superhydrophobic butterfly wings enabled by a controllable composite of assembled carbon nanotube and elastomer is fabricated.Through the adjustment of hydrophobic elastomeric coating, the surface wettability can be effectively controlled and still maintain superhydrophobic characteristics under the applied strain of 60%.The achieved film can function as a self-supported smart umbrella to sensitively monitor the day weather and perform water rescueTwo-dimensional (2D) soft materials, especially in their self-supported forms, demonstrate attractive properties to realize biomimetic morphing and ultrasensitive sensing. Although extensive efforts on design of self-supported functional membranes and integrated systems have been devoted, there still remains an unexplored regime of the combination of mechanical, electrical and surface wetting properties for specific functions. Here, we report a self-supported film featured with elastic, thin, conductive and superhydrophobic characteristics. Through a well-defined surface modification strategy, the surface wettability and mechanical sensing can be effectively balanced. The resulted film can function as a smart umbrella to achieve real-time simulated raining with diverse frequencies and intensity. In addition, the integrated umbrella can even response sensitively to the sunlight and demonstrate a positively correlation of current signals with the intensity of sun illumination. Moreover, the superhydrophobic umbrella can be further employed to realize water rescue, which can take the underwater object onto water surface, load and rapidly transport the considerable weight. More importantly, the whole process of loaded objects and water flow velocity can be precisely detected. The self-supported smart umbrella can effectively monitor the weather and realize a smart water rescue, demonstrating significant potentials in multifunctional sensing and directional actuation in the presence of water.

Direct Actuation of Large Sized Valves by a Hydraulically Relieved Electromechanical Actuation System

Extensive actuation forces and strokes are required for the actuation of large sized valves normally implemented in high power hydraulic systems. A hydraulically piloted operation is, for now, the most suitable solution and state of the art. However, there are some applications where electromechanical valve actuation systems are at advantage against common pilot operation systems. In this contribution it is analyzed in which cases the application of electro-mechanical actuators can be of advantage and why displacement-controlled systems may be one of these applications. A novel electromechanical valve actuation system for large sized 4/3-way directional control valves for the use in displacement-controlled systems is presented. This new actuation system is characterized by a hydraulic relief of the centering springs. Therefore, the springs are only active in safety-critical conditions, such as a power outage. Since the actuator is not working against the spring force during every displacement, the necessary actuation force is reduced drastically. Thus, common electromechanical actuators can be used. In case of a power outage, the spring relief is deactivated causing the stored energy to center the spool in its neutral position. The performance of the novel actuation system is examined through measurements conducted on a manufactured demonstrator for valves of nominal size 25 with a flow rate of up to 600 l/min.