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Although significant progress has been made in coaxial printing of vascularized tissue models, this technique has not yet been used to fabricate stimulus‐responsive scaffolds capable of shape change over time. Here, a new method of direct ink printing (DIP) is proposed with a coaxial nozzle, coaxial 4D printing, enabling the manufacturing of thermoresponsive constructs embedded with a network of interconnected channels. In this approach, a poly(N‐isopropylacrylamide) (PNIPAAm)‐based thermoink is coaxially extruded into either core/sheath microfibers or microtubes. PNIPAAm renders a hydrogel temperature‐sensitive and endows it with a shape‐morphing property both at the micro‐ and macroscale. Specifically, the lumen diameter of the microtubes can be controlled by temperature by 30%. The macrostructural soft actuators can undergo programmed and reversible temperature‐dependent shape changes due to the structural anisotropy of the hydrogel. The permeability tests demonstrate that the hydrogel can possess enough strength to maintain the hollow channels without breaking. In vitro tests confirm the biocompatibility of the material with EA.hy926 cells, paving the avenue for new perfusable soft robots, or active implants. Finally, microalgae Chlamydomonas reinhardtii is combined with the hydrogels to fabricate materials having functions of both living microorganisms and stimuli‐responsive polymers toward creating engineered living materials (ELMs) with a vein‐like geometry. [ABSTRACT FROM AUTHOR]

The dielectric barrier discharge (DBD) actuator has the advantages of being lightweight, having no moving parts, ease of use, and fast response, and has received widespread attention in flow control applications. Turbulence boundary layer drag reduction is one of many applications of DBD flow control, but the mechanism of DBD actuator turbulence drag reduction needs further investigation. The effect of DBD excitation on the skin-friction drag of a turbulent boundary layer on a flat plate at different flow speeds was investigated experimentally. The change in skin-friction drag was measured using oil film interferometry, and the velocity distribution within the boundary layer was obtained using a particle image velocimetry system. The results showed that under the action of the plasma actuator, the local skin-friction coefficient was measured to decrease by 49%. Through dynamic mode decomposition, plasma actuators can increase the thickness of the low-velocity region in the boundary layer, reduce the intensity of Q2 and Q4 events, and inhibit the development of coherent structures, thereby achieving drag reduction. [ABSTRACT FROM AUTHOR]

Direct numerical simulations were performed to examine the control mechanism of a plasma actuator using a dielectric barrier discharge in a rectangular jet with an inlet disturbance. The nozzle has a ratio of 75–10 mm, while the Reynolds number is 3300, and the peak frequency near the nozzle exit is 55 Hz. The jet is controlled by the actuators with conditions of 55 Hz burst frequency, 10% duty ratio, and π phase difference between the upper and lower actuators. The flow field spreads downstream more than that without control. Moreover, the controlling mechanism generates a vortex by inducing flow from the actuator, which grows in size by merging with other vortices generated upstream. Furthermore, the induced flows generate vortices on the upper and lower shear layers that grow in opposite phases of π, and these vortices cause upward and downward flow, respectively, thereby accelerating the spread of the jet. The vortex generated by the induced flow can grow due to its low-streamwise velocity. This occurs regardless of the inlet disturbance because the streakline from the induced flow moves downward near the nozzle surface, causing a rapid decrease in the streamwise velocity after the actuator is stopped. Thus, the actuator's control effect can be explained by the momentary change in the location of the streaklines around it. [ABSTRACT FROM AUTHOR]

This study presents the design and evaluation of a prototype snake-like robot that possesses an actuation system based on shape memory alloys (SMAs). The device is constructed based on a modular structure of links connected by two degrees of freedom links utilizing Cardan joints, where each degree of freedom is actuated by an agonist–antagonist mechanism using the SMA spring-shaped actuators to generate motion, which can be easily replaced once they reach a degradation point. The methodology for programming the spring shape into the SMA material is described in this work, as well as the instrumentation required for the monitoring and control of the actuators. A simplified design is presented to describe the way in which the motion is performed and the technical difficulties faced in manufacturing. Based on this information, the way in which the design is adapted to generate a feasible robotic system is described, and a mathematical model for the robot is developed to implement an independent joint controller. The feasibility of the implementation of the SMA actuators regarding the motion of the links is verified for the case of a joint, and the change in the shape of the snake robot is verified through the implementation of a set of tracking references based on a central pattern generator. The generated tracking results confirm the feasibility of the proposed mechanism in terms of performing snake gaits, as well as highlighting some of the drawbacks that should be considered in further studies. [ABSTRACT FROM AUTHOR]

Exploring the fundamental mechanisms of locomotion extends beyond mere simulation and modeling. It necessitates the utilization of physical test benches to validate hypotheses regarding real-world applications of locomotion. This study introduces cost-effective modular robotic platforms designed specifically for investigating the intricacies of locomotion and control strategies. Expanding upon our prior research in electric–pneumatic actuation (EPA), we present the mechanical and electrical designs of the latest developments in the EPA robot series. These include EPA Jumper, a human-sized segmented monoped robot, and its extension EPA Walker, a human-sized bipedal robot. Both replicate the human weight and inertia distributions, featuring co-actuation through electrical motors and pneumatic artificial muscles. These low-cost modular platforms, with considerations for degrees of freedom and redundant actuation, (1) provide opportunities to study different locomotor subfunctions—stance, swing, and balance; (2) help investigate the role of actuation schemes in tasks such as hopping and walking; and (3) allow testing hypotheses regarding biological locomotors in real-world physical test benches. [ABSTRACT FROM AUTHOR]

Soft robots that incorporate elastomeric matrices and flexible materials have gained attention for their unique capabilities, surpassing those of rigid robots, with increased degrees of freedom and movement. Research has highlighted the adaptability, agility, and sensitivity of soft robotic actuators in various applications, including industrial grippers, locomotive robots, wearable assistive devices, and more. It has been demonstrated that bellow-shaped actuators exhibit greater efficiency compared to uniformly shaped fiber-reinforced actuators as they require less input pressure to achieve a comparable range of motion (ROM). Nevertheless, the mathematical quantification of the performance of bellow-based soft fluidic actuators is not well established due to their inherent non-uniform and complex structure, particularly when compared to fiber-reinforced actuators. Furthermore, the design of bellow dimensions is mostly based on intuition without standardized guidance and criteria. This article presents a comprehensive description of the quasi-static analytical modeling process used to analyze bellow-based soft actuators with linear extension. The results of the models are validated through finite element method (FEM) simulations and experimental testing, considering elongation in free space under fluidic pressurization. This study facilitates the determination of optimal geometrical parameters for bellow-based actuators, allowing for effective biomimetic robot design optimization and performance prediction. [ABSTRACT FROM AUTHOR]

Biological species can walk, swim, fly, jump, and climb with fast response speeds and motion complexity. These remarkable functions are accomplished by means of soft actuation organisms, which are commonly composed of muscle tissue systems. To achieve the creation of their biomimetic artificial counterparts, various biomimetic stimuli-responsive materials have been synthesized and developed in recent decades. They can respond to various external stimuli in the form of structural or morphological transformations by actively or passively converting input energy into mechanical energy. They are the core element of soft actuators for typical smart devices like soft robots, artificial muscles, intelligent sensors and nanogenerators. Significant progress has been made in the development of bioinspired stimuli-responsive materials. However, these materials have not been comprehensively summarized with specific actuation mechanisms in the literature. In this review, we will discuss recent advances in biomimetic stimuli-responsive materials that are instrumental for soft actuators. Firstly, different stimuli-responsive principles for soft actuators are discussed, including fluidic, electrical, thermal, magnetic, light, and chemical stimuli. We further summarize the state-of-the-art stimuli-responsive materials for soft actuators and explore the advantages and disadvantages of using electroactive polymers, magnetic soft composites, photo-thermal responsive polymers, shape memory alloys and other responsive soft materials. Finally, we provide a critical outlook on the field of stimuli-responsive soft actuators and emphasize the challenges in the process of their implementation to various industries. [ABSTRACT FROM AUTHOR]

Surfaces with high aspect ratio microarray structures can implement sophisticated assignment in typical fields including microfluidics, sensor, biomedicine, et al. via regulating their deformation or the material properties. Inspired by natural materials and systems, for example sea cockroaches, water spiders, cacti, lotus leaves, rice leaves, and cedar leaves, many researchers have focused on microneedle functional surface studies. When the surface with high aspect ratio microarray structures is stimulated by the external fields, such as optical, electric, thermal, magnetic, the high aspect ratio microarray structures can undergo hydrophilic and hydrophobic switching or shape change, which may be gifted the surfaces with the ability to perform complex task, including directional liquid/air transport, targeted drug delivery, microfluidic chip sensing. In this review, the fabrication principles of various surfaces with high aspect ratio microarray structures are classified and summarized. Mechanisms of liquid manipulation on hydrophilic/hydrophobic surfaces with high aspect ratio microarray structures are clarified based on Wenzel model, Cassie model, Laplace pressure theories and so on. Then the intelligent control strategies have been demonstrated. The applications in microfluidic, drug delivery, patch sensors have been discussed. Finally, current challenges and new insights of future prospects for dynamic manipulation of liquid/air based on biomimetic surface with high aspect ratio microarray structures are also addressed. [Display omitted] [ABSTRACT FROM AUTHOR]

This paper investigates the problem of neuroadaptive fixed-time control for full-state constrained strict-feedback nonlinear systems subject to actuator faults. A fixed-time control strategy combined with barrier Lyapunov functions and neuroadaptive backstepping is proposed, and a neural network is employed to approximate the packaged unknown nonlinear terms and nonlinear actuator faults. By constructing barrier Lyapunov functions, it can be ensured that none of the strict-feedback systems' states will transgress their constraint bounds. Additionally, a fixed-time controller is designed such that all the signals in the closed-loop system are bounded, and the output is driven to track the reference signal to a small neighborhood within a fixed time. The benefits and feasibility of the proposed control method are also confirmed by simulations. [ABSTRACT FROM AUTHOR]

Electronic textiles (E‐textiles) are made using various materials including carbon nanotubes, graphene, and graphene oxide. Among the materials here, e‐textiles are fabricated with reduced graphene oxide (rGO) coating on commercial textiles. rGO‐based yarns are prepared for e‐textiles by a simple dip coating method with subsequent non‐toxic reduction. To enhance the conductivity, the rGO yarns are coated with poly(3,4‐ethylene dioxythiophene): poly(styrenesulfonic acid) (PEDOT) followed by electrochemical polymerization of polypyrrole (PPy) as the electromechanically active layer, resulting in textile actuators. The rGO‐based yarn actuators are characterized in terms of both isotonic displacement and isometric developed forces, as well as electron microscopy and resistance measurements. Furthermore, it is demonstrated that both viscose rotor spun (VR) and viscose multifilament (VM) yarns can be used for yarn actuators. The resulting VM‐based yarn actuators exhibit high strain (0.58%) in NaDBS electrolytes. These conducting yarns can also be integrated into textiles and fabrics of various forms to create smart e‐textiles and wearable devices. [ABSTRACT FROM AUTHOR]

3D printable inks for the preparation of magnetic hydrogel actuators are difficult to formulate because magnetic nanoparticles tend to aggregate without stabilization through other ink components. At the same time, such inks need to be shear‐thinning and recover their high viscosity state sufficiently fast to be suitable for the printing process. Here, the use of chitosan as dispersing agent for Fe2O3 nanoparticles is reported. Combined with Pluronic F127 as a rheology modifier and acrylamide as the base monomer, thermoresponsive and shear‐thinning magnetic inks containing well‐dispersed particles are obtained. The ink viscosity is tuned over two orders of magnitude by varying the chitosan and Pluronics F127 content. 3D‐printed shapes with good shape fidelity are obtained at a print bed temperature of 50 °C, where aggregation of the Pluoronics F127 micelles occurs. This leads to a fast recovery of the high viscosity state of the material, so that the printed shape can then be locked in by UV cross‐linking. This treatment yielded magneto‐responsive prototypes which are promising for soft robotics applications. Thanks to the simplicity of the ink formulation, it is easily transferable also to nonspecialist laboratories, and the concept is potentially applicable also to other types of nanoparticles. [ABSTRACT FROM AUTHOR]

Generally, control system design and the associated assessment of control system quality focuses on cutting-edge performance. Most of the approaches and applied indicators aim for this goal. However, the current times increasingly indicate the need to consider, at least on an equal level, the issue of the resistance of the control system and the energy that it consumes. Indicators for the assessment of the quality of control system operation should take these aspects into account. This study focuses on energy issues. It should be noted that, very often, an actuator device, such as a pump, motor, or actuator, consumes energy. In small single-loop systems, the share of this energy is usually negligible, but in large installations, it begins to reach significant values. This work proposes a multi-criteria assessment of the operation of control systems using information about the control signal. The energy factor can be considered in the form of a quadratic relationship or using the valve travel and valve stroke indicators known in other contexts. The index ratio diagram (IRD) approach is utilized as an energy assessment tool. At the same time, an analysis is carried out showing the impact of energy on other known indicators based on the control error. Finally, a methodology incorporating energy consumed by the control system is proposed. [ABSTRACT FROM AUTHOR]

The Non-Synchronizer Automated Mechanical Transmission (NSAMT) demonstrates a straightforward structure and cost-effectiveness; however, the primary obstacle to its widespread application lies in NSAMT shift control. The implementation of active angle alignment effectively addresses the issue of shifting quality, but achieving active angle alignment necessitates precise tracking of the planned shifting curve by the gear-shifting actuator. To tackle the control problem of accurate tracking for NSAMT shift actuators, this paper initially analyzes the structure and shift characteristics of the NSAMT. Based on this analysis, a physical model is established using Amesim, incorporating a drive motor, two-gear NSAMT, shift actuator, sleeve, and DC motor model. An extended state observer (ESO) is designed to mitigate unknown interference within the system. Furthermore, an active angle alignment control algorithm based on "zero speed difference" and "zero angle difference" for double target tracking is constructed while planning the axial motion trajectory of the sleeve. The Backstepping algorithm is employed to successfully track and regulate this planned trajectory. Finally, through Hardware-in-the-Loop testing, we validate our proposed control strategy, which demonstrates consistent results with simulation outcomes, thereby affirming its effectiveness. [ABSTRACT FROM AUTHOR]

Although various studies on vibration control schemes exist, most of them focus on a one-time optimization of actuator layout. However, numerical results indicate significant drawbacks of fixed layouts on control performance, a factor rarely mentioned in the field of vibration control. This study aims to address this gap by proposing a novel rearrangement strategy that adaptively varies the actuator layout based on the vibration intensity pattern. The inspiration for this approach comes from the reorientation of cortical microtubules in plant cells, which adapt to stress patterns. The study first derives the definitions of vibration patterns and the index of intensity based on energy transfer. These definitions then guide the optimization of actuator layout throughout the control process. The study compares the fixed layout with the proposed adaptive varying layout, considering both full-state feedback and recognition feedback. The numerical results demonstrate that the proposed adaptive rearrangement of actuator layout significantly improves suppression performance, leading to higher utilization efficiency of control forces. Additionally, the presented strategy is tolerant to computation errors from recognition feedback, resulting in robust enhancements in vibration attenuation. Our study has introduced new possibilities for improving existing control schemes. • First-time practical dynamic rearrangement strategy adapts actuator layout based on system responses. • A bioinspired optimization framework aligns the actuator layout with a vibration intensity pattern in a fast-computing manner. • The strategy is compatible with both full-state feedback and recognition reconstructed from sensing signals. • Simulations show improved control performance with increased force utilization and error tolerance. [ABSTRACT FROM AUTHOR]

Summary: The consensus tracking mechanism of a multi‐agent system consisting of third‐order nonlinear single joint manipulators was investigated in this study based on the pertinent industrial context. Unlike many previous studies on consensus control that presumed a known control direction, this investigation addressed the complex challenges posed by unknown control directions and time‐varying actuators. Specifically, we explored both time‐invariant and time‐varying actuator faults in scenarios wherein all parameters are unknown. The Nussbaum function was utilized to resolve time‐varying nonlinear fault‐tolerance and unknown control direction problems. In the design process of the control law, the backstepping method combining with Nussbaum function is adopted to address unmatched nonlinearity and unmatched uncertainty system, and the radial basis function neural network is used to approximate the unknown parameters The resulting control law allows all robotic manipulators to track the angle and angular velocity of the leader. Simulation results demonstrate the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the fuzzy adaptive time‐varying formation control problem for fully‐actuated unmanned surface vehicles (USVs) systems. The studied USVs systems include uncertain dynamics and actuator faults. Fuzzy logic systems (FLSs) and disturbance observer are employed to estimate uncertain nonlinear dynamics in system model and external time‐varying disturbances, respectively. Meanwhile, the prescribed performance control (PPC) technique is applied to construct the constraint requirements of collision avoidance and connectivity preservation in time‐varying formation control. Additionally, a new robust adaptive fault‐tolerant control (FTC) algorithm is presented. Hence, by the aid of adaptive backstepping technique with performance functions, a robust fuzzy adaptive time‐varying formation FTC scheme of time‐varying formation is developed. The proposed formation control scheme not only has the advantages of avoiding collision and preserving connectivity, but also ensures all the signals are uniformly ultimately bounded (UUB). Finally, the simulation results are provided to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Water plays an important role in the properties of cellulose. In materials design, the water uptake of cellulose has been traditionally seen as a drawback, since water reduces mechanical resistance of paper and cardboard, and at high hydration, cellulose-based products are disintegrated. However, recently, the hydration of cellulose has been considered as an advantage to design water-responsive soft actuators. In Nature, water is the fuel for several plant functions that involve motion, such as the seed release or the plant protection from high temperature and radiation. Inspired by these natural systems, cellulose-based actuators have been designed to display different movements (bending, twisting, curling) in response to water. Biopolymer structuration inducing anisotropy within the system allows the asymmetric expansion of layers, which results in macroscopic movement. This review gives an overview of the soft actuators triggered by the hydration/dehydration processes of cellulose. We present representative examples of water-triggered natural actuators, which have inspired researchers to design anisotropic cellulose-based materials that develop controlled movement in response to water. [ABSTRACT FROM AUTHOR]

Facial paralysis is a highly burdening condition, resulting in a patient's inability to move his mimic musculature on one or both sides of his face. This condition compromises the patient's communication and facial expressions, and thus dramatically reduces his quality of life. The current treatment for chronic facial paralysis relies on a complex reconstructive surgery. This publication proposes a novel, less invasive approach for dynamic facial reanimation. The use of a smart material, namely a Dielectric Elastomer Actuator (DEA) is proposed for facial motion restoration, thus avoiding the traditional two-stage free muscle transfer procedure and allowing for a faster recovery of the patient. DEAs are a type of electroactive polymers, showing promising properties similar to natural muscles such as the fact that they are soft, lightweight and allow for large displacements. As a result, a study of the facial muscles and neural interfaces, notably the ones responsible for mouth movement, was performed, in order to implement a realistic setup. In this paper, a non-invasive neural interface based on myoelectric signal is used in order to establish a real-time control of the actuator. Visible motion of a skin model is produced in real time, by synchronizing the actuator to the activity of a healthy muscle, with a maximal delay of 108 ms resulting from the signal processing and a delay of less than 30 ms related to the actuation of the DEA. This shows that the usage of DEA combined with a neural interface presents a promising approach for treatment of facial paralysis. [ABSTRACT FROM AUTHOR]

We address the theoretical and practical problems related to the trajectory generation and tracking control of tail-sitter UAVs. Theoretically, we focus on the differential flatness property with full exploitation of actual UAV aerodynamic models, which lays a foundation for generating dynamically feasible trajectory and achieving high-performance tracking control. We have found that a tail-sitter is differentially flat with accurate (not simplified) aerodynamic models within the entire flight envelope, by specifying coordinate flight condition and choosing the vehicle position as the flat output. This fundamental property allows us to fully exploit the high-fidelity aerodynamic models in the trajectory planning and tracking control to achieve accurate tail-sitter flights. Particularly, an optimization-based trajectory planner for tail-sitters is proposed to design high-quality, smooth trajectories with consideration of kinodynamic constraints, singularity-free constraints, and actuator saturation. The planned trajectory of flat output is transformed into state trajectory in real time with optional consideration of wind in environments. To track the state trajectory, a global, singularity-free, and minimally parameterized on-manifold MPC is developed, which fully leverages the accurate aerodynamic model to achieve high-accuracy trajectory tracking within the whole flight envelope. The proposed algorithms are implemented on our quadrotor tail-sitter prototype, "Hong Hu," and their effectiveness are demonstrated through extensive real-world experiments in both indoor and outdoor field tests, including agile SE(3) flight through consecutive narrow windows requiring specific attitude and with speed up to 10 m/s, typical tail-sitter maneuvers (transition, level flight, and loiter) with speed up to 20 m/s, and extremely aggressive aerobatic maneuvers (Wingover, Loop, Vertical Eight, and Cuban Eight) with acceleration up to 2.5 g. The video demonstration is available at https://youtu.be/2x_bLbVuyrk. [ABSTRACT FROM AUTHOR]

Semiconductor photolithography equipment requires an actuation system that can satisfy high acceleration and precision demands on the nanoscale in order to operate with high throughput and efficiency. Reluctance actuators, which offer greater acceleration and force output than conventional Lorentz actuators, are one option. The photolithography technique uses a floating stage with air bearings to reduce friction; nonetheless, vibration transfer is not completely prevented, potentially causing misalignment and asymmetries between the actuator components. The output force can be significantly impacted by unequal offsets between the mover and stator. In the paper that follows, a technique for calculating the force of various asymmetrical instances for the C-core reluctance actuator is demonstrated. This paper looks into the effect of rotational offsets in all rotational degrees of freedom occurring simultaneously. Previously, only each degree of freedom was analyzed. Analytical models are developed and compared to Comsol Multiphysics (COMSOL) simulations, and experimental findings show accuracy to be within almost 10% for the ranges examined. The findings presented can allow for future control systems to be designed to counteract multi-axial asymmetric issues. • Derived an analytical equation of the output force under multi-axial angular offsets. • Implemented a FEM setup to further tune the analytical output force equation. • Tested experimentally on multi-axial offset cases to verify the analytical model. [ABSTRACT FROM AUTHOR]

In this paper, event-triggered control for uncertain delayed neural networks (DNNs) with actuator saturation against deception attack is discussed. We propose a novel framework into which an event-triggered mechanism (ETM), actuator saturation, system uncertainty, and deception attack are combined. In the framework, the discrete ETM is employed to determine whether the sampled signal should be transmitted to controller so as to save network bandwidth, a random occurrence deception attack model satisfying Bernoulli distribution is introduced to construct the system robust, and actuator saturation is considered due to the actual complex network environment. Based on the framework, we discussed the stochastic stability of a novel delayed neural network model in a closed-loop system. By resorting to the appropriate Lyapunov–Krasovskii functional (LKF), we derive some new sufficient conditions for the stochastically stable of the system and obtain the gain of the system controller using efficient linear matrix inequality (LMI) method. Finally, a numerical example, in the end, demonstrates the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, $ \mathcal {H}_{\infty } $ H ∞ observer-based consensus for a class of nonlinear multiagent systems (MASs) with actuator saturation and input delays are estimated. A new delay-dependent region partitioning approach has been introduced in multiagent systems. The state information of the leader can be obtained by designing a distributed observer for each follower. Based on the state information of the follower and the estimated state information of the neighbouring agents, a distributed controller has been developed. With the help of a novel Lyapunov–Krasovakii functional (LKF), using a region partitioning approach combined with Wirtinger inequalities, a sufficient condition is established in terms of Linear Matrix Inequality (LMI). Finally, simulation examples are presented to the applicability of the proposed theoretical results. [ABSTRACT FROM AUTHOR]

This paper addresses the finite-time control problem of a class of uncertain nonlinear systems subject to input saturation and actuator faults. To approximate the unknown system states, a fuzzy state observer is established where fuzzy logic systems are utilized to estimate the unknown nonlinearities. A nonlinear disturbance observer to estimate the external disturbance of the system. A new finite-time adaptive fuzzy controller is constructed together with the proposed disturbance and state observers, which can guarantee the tracking error into a small neighborhood around zero within finite time. To avoid the tedious and arithmetic problems brought by the traditional backstepping control, the dynamic surface technique is applied, which can effectively reduce the computation burden. It can be proved that not only the boundedness of the closed-loop system states can be guaranteed but also the tracking error is regulated into a small range near the equilibrium in finite time, despite unknown actuator faults and input saturation. Finally, the simulations of two-stage chemical reactor nonlinear system are conducted to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Ride comfort is an important indicator to evaluate the dynamic performance of automotive vehicles. One method for improving ride comfort is to incorporate an active actuator into the passive suspension. However, the improvement is closely linked with the required actuation power and force. Increased actuation requirements may lead to higher energy consumption and a larger actuator size. To enhance the trade-off between ride comfort and active actuation requirements, a new design approach for searching for the optimal passive-active-combined suspension across many different mechanical component layouts incorporating an inerter is proposed in this paper. Compared with traditional designs where the suspension is limited to a few special layouts, via this approach the optimal passive part among all network possibilities with pre-determined numbers of each element type (springs, dampers and inerters), and optimal controller parameters of the parallel active actuator can be identified. Considering a quarter-car model, with a benchmark combined active-passive suspension in which the passive part is a spring-damper, the optimal inerter-based suspension can reduce the active force by more than 48% and regenerate 6 W more average power in the active part while achieving the same ride comfort. Note that in this case, two constraints are always considered: the road-holding ability (as indicated by the dynamic tyre load) and suspension travel of the identified suspension will not be worse than those of the benchmark suspension. The optimal trade-off obtained with this approach serves as a powerful tool in the automotive suspension design as it provides guidance on the following three aspects: the optimal ride comfort, the minimum power consumption and the feasibility of specific actuation requirements, where the second point is obtained in conjunction with the power conservation theorem proposed in this paper which proves that the total power consumed by the passive and active parts will not vary with changes in the passive part and active controller parameters. [ABSTRACT FROM AUTHOR]

This paper considers the problem of unmanned aerial vehicle (UAV) aerial collision net recovery in a three-dimensional non-decoupling environment and approach angle constraint. A robust control-observer framework-based guidance law was designed via the nonsingular fast terminal sliding mode control (NFTSMC) technique and adaptive sliding mode disturbance observer (ASMDO). To estimate the disturbance of the guidance system in finite time, an ASMDO is presented in which the parameters are autonomously adjustable according to the estimation error. The proposed control implementation uses the nonsingular fast terminal sliding mode (NFTSM) technique to drive the line-of-sight (LOS) angle error and LOS angular rate fast convergence under model coupling and external disturbance. Furthermore, regarding the actuator of UAV with second-order dynamic, a backstepping guidance law to compensate for actuator dynamics is proposed with the aid of a finite-time converged differentiator, which can estimate directly the derivative of the virtual control law and guarantee the finite-time convergent characteristic of the partially integrated guidance and control system. Simulation studies and comparisons verified the efficiency of the proposed guidance law in the presence of a complex disturbance lump. [ABSTRACT FROM AUTHOR]

[Display omitted] Gel actuators are a kind of soft intelligent material that can convert external stimuli into deformations to generate mechanical responses. The development of gel actuators with advanced structures to integrate multiple responsiveness, programmability, and fast deformation ability is urgently needed. Here, we explored a poly(7-(2-methacryloyloxyethoxy)-4-methylcoumarin- co -acrylic acid- co -glycol) ternary gel network as an actuator with reprogrammable photo/H 2 O dual responsibilities. In such a design, [2 + 2] photodimerization and photocleavage reactions of coumarin moieties can be realized under 365 and 254 nm light irradiation, respectively, affording reversible photodriven behaviour of the gels. The abundant carboxylic acid in the backbone has the capacity to form additional crosslinks to assist and accelerate the photodriven behaviour. The incorporation and orientation of halloysite nanotubes (HNTs) in gel matrices support an axial direction force and result in a more controllable and programmable actuating behaviour. The synergistic response enables fast grasping-releasing of 5-times the weight of the object in water within 10 min by fabricating HNT-incorporated gels as a four-arm gripper. [ABSTRACT FROM AUTHOR]

Anti-ferroelectric (AFE) dielectrics are promising for actuators due to their large strain resulting from the phase transition from AFE phase to ferroelectric (FE) phase. However, their high phase transition electric field and strain hysteresis (H s) limit their application in actuators. In this work, La-Nb co-doping in Pb(Zr 0.85 Sn 0.08 Ti 0.07)O 3 AFE ceramics realizes collaborative optimization of AFE-FE phase transition electric field (E AFE-FE), H s and strain. La3+ ions replace Pb2+ ions to weaken long-range FE coupling and refine hysteresis loops. Nb5+ ions replacing B-site ions enhance the stability of FE phase in PZST ceramics, hence further reducing E AFE-FE. Furthermore, doping Nb5+ decreases grain size, which is conducive to producing higher field-induced strains. As a result, E AFE-FE decreases from 119 kV cm−1 to 47 kV cm−1 and H s decreases from 75 % to 44 %, while strain remains at 0.47 %. The results demonstrate that La-Nb co-doping strategy promotes the application of large-strain AFE materials in actuators. • La3+ ions replacing Pb2+ ions can weaken long-range ferroelectric coupling and refine hysteresis loops. • Nb5+ ions replacing B-site ions reduce AFE-FE phase transition electric field and hysteresis. • Doping of Nb5+ decreases grain size, producing larger field-induced strains. • Co-doping La3+ and Nb5+ in PZST ceramics can achieve co-optimization of phase change electric field, hysteresis, and strain for applications in actuators. [ABSTRACT FROM AUTHOR]

This study presents a novel hybrid control strategy for the active hitch system, named the Dynamic Hitch Lift (DHIL), comprising a hybrid controller and a force actuator. The controller was designed to mitigate longitudinal load transfer in heavy combination vehicles by reducing the semitrailer pitch rate and rejecting the pitch moment, assisted by the virtual Skyhook moment. The new controller can calculate the desired force of the DHIL actuator to counter incoming load transfer during harsh braking exceeding 0.5 g braking deceleration. The proposed controller was assessed using a verified 12-degrees-of-freedom tractor-semitrailer model in harsh braking tests across different vehicle configurations. The first evaluation involved a stability test to demonstrate the stability of the controller in reducing load transfer across different vehicle configurations. The second evaluation was on controller performance, which revealed that the dynamic vehicle response has efficiently reduced load transfer by up to 9.14%. The third evaluation has focused on the DHIL actuator performance, which indicated that the actuator generated a force of 159,197 N, which translated into a stepper motor torque of 1,695 Nm at a speed of 1,000 rpm. Simulation results affirmed that the proposed DHIL controller was stable and could effectively reduce longitudinal load transfer in heavy combination vehicles during harsh braking. [ABSTRACT FROM AUTHOR]

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Purpose: In the paper, a theoretical analysis—based on a 2D multibody model—is presented regarding active vibration control of a rotating machine with voltage-driven electrodynamic actuators between machine feet and steel frame foundation under multiple base excitations. Methods: Mathematical formulations are derived in the time domain and then transferred into the Laplace domain, where a state space formulation is used to describe the controlled vibration system. With this mathematical formulations, it is possible to analyze separately the two different kinds of actuator forces—the actuator forces, caused by the motion-induced voltage and the actuator forces caused by the control system—and their influence on the vibration behavior. Afterward, the mathematical formulations are transferred into the Fourier domain, for considering harmonic excitations of the base. Also a numerical example is presented, where different cases regarding machine mounting and operation conditions are investigated and compared to each other. Results: It could be clearly demonstrated that with the presented control system, most of the resonance peaks in the frequency responses could be strongly damped. Conclusions: With the presented mathematical formulations, the controlled vibration system can be well described, considering separately the two different kinds of electrodynamic actuator forces and their influence. [ABSTRACT FROM AUTHOR]

The longitudinal dispersion of the projectile in shooting tests of two-dimensional trajectory corrections fused with fixed canards is extremely large that it sometimes exceeds the correction ability of the correction fuse actuator. The impact point easily deviates from the target, and thus the correction result cannot be readily evaluated. However, the cost of shooting tests is considerably high to conduct many tests for data collection. To address this issue, this study proposes an aiming method for shooting tests based on small sample size. The proposed method uses the Bootstrap method to expand the test data; repeatedly iterates and corrects the position of the simulated theoretical impact points through an improved compatibility test method; and dynamically adjusts the weight of the prior distribution of simulation results based on KullbackeLeibler divergence, which to some extent avoids the real data being "submerged" by the simulation data and achieves the fusion Bayesian estimation of the dispersion center. The experimental results show that when the simulation accuracy is sufficiently high, the proposed method yields a smaller mean-square deviation in estimating the dispersion center and higher shooting accuracy than those of the three comparison methods, which is more conducive to reflecting the effect of the control algorithm and facilitating test personnel to iterate their proposed structures and algorithms.; in addition, this study provides a knowledge base for further comprehensive studies in the future. [ABSTRACT FROM AUTHOR]

In this paper, an integrated guidance and control method based on an adaptive path-following controller is proposed to control a spin-stabilized projectile with only translational motion information under the constraint of an actuator, uncertainties in aerodynamic parameters and measurements, and control system complexity. Owing to the fairly high rotation speed, the dynamic model of this missile is strongly nonlinear, uncertain and coupled in pitch, yaw and roll channels. A theoretical equivalent resultant force and uncertainty compensation method are comprehensively used to realize decoupling of pitch and yaw. In response to the strong nonlinear and time-varying characteristics of the dynamic system, the quasi-linear model whose parameters are obtained by interpolation of points selected as the segmentation points in the trajectory envelope, is used for calculation in each step. To cope with the system uncertainty caused by model approximation, parameter uncertainty and ballistic interference, an extended state estimator is used to compensate the output feedback according to the test ballistic angle. In order to improve the tracking efficiency and ensure the tracking error convergence with only translational motion information, the virtual guide point, whose derivative is deduced according to the Lyapunov principle, is calculated in real time according to the projection relationship between the real-time position and the reference trajectory, and a virtual line-ofsight angle and the backstepping method are used for the design of the guidance and control system. In order to avoid the influence of control input saturation on the guidance and control performance due to the actuator limitation and improve the robustness of the system, an anti-saturation compensator is designed according to the two-step method. The feasibility and effectiveness of the path-following controller is verified through closed-loop flight simulations with measurement, control, and condition uncertainties. The results indicate that the designed controller can converge to the reference path and evidently decrease the distance between the impact point and target under different uncertainties. [ABSTRACT FROM AUTHOR]

A novel dynamic economic model-predictive control strategy is presented that improves wind farm power production and reduces the additional demands of wake steering on yaw actuation when compared to an industry state-of-the-art reference controller. The novel controller takes a distributed approach to yaw control optimisation using a free-vortex wake model. An actuator-disc representation of the wind turbine is employed and adapted to the wind farm scale by modelling secondary effects of wake steering and connecting individual turbines through a directed graph network. The economic model-predictive control problem is solved on a receding horizon using gradient-based optimisation, demonstrating sufficient performance for realising real-time control. The novel controller is tested in a large-eddy simulation environment and compared against a state-of-the-art look-up table approach based on steady-state model optimisation and an extension with wind direction preview. Under realistic variations in wind direction and wind speed, the preview-enabled look-up table controller yielded the largest gains in power production. The novel controller based on the free-vortex wake produced smaller gains in these conditions while yielding more power under large changes in wind direction. Additionally, the novel controller demonstrated potential for a substantial reduction in yaw actuator usage. [ABSTRACT FROM AUTHOR]

Soft Actuator Based on a Novel Variable Stiffness Compound Extensor Bending-Pneumatic Artificial Muscle (CEB-PAM): Design and Mathematical Model [ABSTRACT FROM AUTHOR]

For the nonlinear continuous‐time switched system with input saturation under asynchronous switching action, the problem of actuator failure is investigated in the presence of external disturbances. Firstly, a sufficient condition for the robust exponential stabilization of system is obtained by using the minimum dwell‐time method combining the piecewise Lyapunov function method. Secondly, a sufficient condition for the tolerance disturbances of the system is obtained by using the similar approach. Thirdly, the weighted L2$$ {L}_2 $$‐gain is analysed. Then, we maximize the estimation of the domain of attraction for the closed‐loop system by taking the shape of a set into consideration. Furthermore, the fault‐tolerant state feedback controllers are designed, which aim at enlarging the estimation of domain of attraction for the closed‐loop system and obtaining the maximum value of tolerance disturbance and the minimum upper bound on the weighted L2$$ {L}_2 $$‐gain. Last but not least, we give a numerical example to verify the effectiveness of the proposed approach and compare the state responses curve under the action of the fault‐tolerant and the standard controller. [ABSTRACT FROM AUTHOR]

This article discusses the modeling and analysis of a thermo-electro-magneto-viscoelastic actuator made of an electro-magneto-active polymer. The study develops a dynamic model to analyze the behavior of the actuator, considering thermal, electrical, and mechanical factors. The study evaluates the stability, periodicity, and resonant behavior of the actuator and provides insights into the design of modern actuators for engineering and medical industries. The text also discusses the role of viscoelasticity and temperature in modeling the behavior of smart polymer-based devices. It emphasizes the need for further research in this area and presents a theoretical framework for studying the nonlinear behavior of TEMVE actuators. The document includes references for further reading on related topics. [Extracted from the article]

Air cylinders are actuators that slide a piston inside cylinders by applying air pressure. We propose an air-cylinder-type artificial muscle that can be flexibly bent by using a flexible tube for the cylindrical part. The actuator output was a string connected to a piston. When the air-cylinder-type artificial muscle bends, the inner wall of the tube and the string come into contact, causing output fluctuations owing to friction. In this study, we investigated the output when an artificial muscle was bent. After describing the structure of the air-cylinder-type artificial muscle, the measurement results of the resistance force at each part of the actuator are presented. A theoretical output inspired by the capstan equation was derived, and its validity was verified by comparison with experimental results. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to create a low‐cost and user‐friendly water‐induced actuator based on hydrophobic papers and a simple embossing method. By injecting water onto the papers through microfluidic channels made by embossing, fast and reversible bending actuation can be induced. The actuation angle and speed are dependent on the amount and duration of the water applied, which allows the actuator to be effectively controlled by syringe injection/drawing without the need for an external power supply. A bending angle of >90° can be achieved in ≈15 s, with complete reversal attainable in ≈3 min; and the actuation can be induced again by resting for ≈1 h after the reversal. This work represents a significant contribution to the field of paper‐based microfluidics by demonstrating actuation in a battery‐free, low‐cost, and simple approach, with potential applications in paper‐based analytical devices such as medical diagnostics. [ABSTRACT FROM AUTHOR]

Real‐time hybrid simulation (RTHS) is an innovative experimental testing technique that tests only some structural components for which accurate numerical models do not exist (i.e., experimental substructure), while modeling the rest of the structure numerically (i.e., numerical substructure). Conventionally, the two substructures in RTHS are executed at the same rate and interact in real time. Multi‐rate real‐time hybrid simulation (mrRTHS) is a modification of RTHS where different time step sizes are applied to the numerical substructure computation and the actuator control. This configuration provides a larger allowance for real‐time execution, thereby enabling the use of higher‐fidelity numerical models in RTHS. However, it complicates the data transmission between the substructures and introduces an additional time delay. The increased delay consists of communication and computational delays, which are independent of actuator dynamics. This study compares the data transmission within RTHS and mrRTHS configurations and confirms that mrRTHS experiences a larger delay error. To improve the accuracy of mrRTHS, a time‐varying interpolation built with Chebyshev polynomials is used. Additionally, a compensation strategy based on an adaptive discrete feedforward controller is introduced to compensate for actuator‐induced tracking errors and the increased time delay in mrRTHS. A demonstrative experimental study is conducted to investigate the seismic behavior of a large‐scale base‐isolated structure equipped with gyromass dampers. The results indicate that the proposed mrRTHS compensation strategy facilitates a more realistic assessment of the dynamic performance of structural systems by employing higher‐fidelity numerical substructures in mrRTHS. [ABSTRACT FROM AUTHOR]

Plasma actuators have demonstrated great potential for active flow control applications, including boundary layer control, flow separation delay, turbulence control, and aircraft noise reduction. In particular, the material used as a dielectric barrier is crucial for the proper operation of the device. Currently, the variety of dielectrics reported in the literature is still quite restricted to polymers including Kapton, Teflon, poly(methyl methacrylate) (PMMA), Cirlex, polyisobutylene (PIB) rubber, or polystyrene. Nevertheless, several studies have highlighted the fragilities of polymeric dielectric layers when actuators operate at significantly high-voltage and -frequency levels or for long periods. In the current study, we propose the use of alumina-based ceramic composites as alternative materials for plasma actuator dielectric layers. The alumina composite samples were fabricated and characterized in terms of microstructure, electrical parameters, and plasma-induced flow velocity and compared with a conventional Kapton-based actuator. It was concluded that alumina-based dielectrics are suitable materials for plasma actuator applications, being able to generate plasma-induced flow velocities of approximately 4.5 m/s. In addition, it was verified that alumina-based ceramic actuators can provide similar fluid mechanical efficiencies to Kapton actuators. Furthermore, the ceramic dielectrics present additional characteristics, such as high-temperature resistance, which are not encompassed by conventional Kapton actuators, which makes them suitable for high-temperature applications such as turbine blade film cooling enhancement and plasma-assisted combustion. The high porosity of the ceramic results in lower plasma-induced flow velocity and lower fluid mechanical efficiency, but by minimizing the porosity, the fluid mechanical efficiency is increased. [ABSTRACT FROM AUTHOR]

Soft robots, inspired by biological adaptability, can excel where rigid robots may falter and offer flexibility and safety for complex, unpredictable environments. In this paper, we present the Omnidirectional Bending Actuator (OBA), a soft robotic actuation module which is fabricated from off-the-shelf materials with easy scalability and consists of three pneumatic chambers. Distinguished by its streamlined manufacturing process, the OBA is capable of bending in all directions with a high force-to-weight ratio, potentially addressing a notable research gap in knit fabric actuators with multi-degree-of-freedom capabilities. We will present the design and fabrication of the OBA, examine its motion and force capabilities, and demonstrate its capability for stiffness modulation and its ability to maintain set configurations under loads. The mass of the entire actuation module is 278 g, with a range of omnidirectional bending up to 90.80°, a maximum tolerable pressure of 862 kPa, and a bending payload (block force) of 10.99 N, resulting in a force-to-weight ratio of 39.53 N/kg. The OBA's cost-effective and simple fabrication, compact and lightweight structure, and capability to withstand high pressures present it as an attractive actuation primitive for applications demanding efficient and versatile soft robotic solutions. [ABSTRACT FROM AUTHOR]

With the development of safety technologies for intelligent commercial vehicles, electronic pneumatic braking systems (EBSs) have been widely used. However, EBS actuators may fail during vehicle operation and thus create safety problems. For this reason, we propose a path-tracking fault-tolerant control strategy under EBS actuator failure in intelligent commercial vehicles. First, in order to be able to characterize different types of brake actuator faults during the EBS differential braking process of a vehicle, a comprehensive fault coefficient for calculating the degree of fault is designed, and a BES generalized fault model is established. Second, the faults are introduced into the fault-tolerant controller through the comprehensive fault coefficients for braking torque calculation and braking pressure allocation. Thus, a vehicle path model with the complete fault coefficients as variable parameters is established. Then, based on the LPV system gain scheduling, a path-tracking LPV/H∞ fault-tolerant controller under EBS actuator faults in commercial vehicles is designed, which is used to solve the safety problem arising from sudden EBS actuator faults. Finally, we conducted experimental validation through hardware-in-the-loop tests. The results demonstrate that the control strategy designed in this paper redistributes the braking torque and synergizes with the steering system to enhance vehicle stability, thereby improving vehicle safety in the EBS failure mode. [ABSTRACT FROM AUTHOR]

When using electric linear drives for vertical positioning of workloads, a constant force both during movement and at standstill must be supplied to compensate gravity. Compensating stationary forces by the use of passive components reduces the power consumption of the employed actuator and permits smaller dimensioning. In this article, we present a novel integrative actuator design which combines the inherent advantages of a permanent magnetic weight compensation with a two-phase linear direct drive. We illustrate how to design permanent magnetic force compensation to realize a constant compensating force over a desired actuator stroke. Analytical solutions for both the design of the direct drive and the design of the permanent magnetic weight compensation are derived and validated by simulation and experiment. The innovative actuator design is compared to a conventional, non-compensated drive, and we aim to provide the reader with insights into specific applications where the use of the weight-compensated actuator proves particularly effective. [ABSTRACT FROM AUTHOR]

This article discusses the importance of control schemes in improving the performance and reliability of actuators. It provides an overview of various control schemes, including Model Predictive Control, Fuzzy Logic Control, and Neural Network Control, among others. The choice of control scheme depends on the system's characteristics, desired performance, and environmental conditions. The article also summarizes specific research papers that explore different control schemes in depth, covering topics such as fault diagnosis and control strategies for electric vehicles, friction compensation control for robot manipulators, and trajectory control for precision linear stages. The summary concludes by acknowledging the authors and reviewers for their contributions to the special issue. [Extracted from the article]

This paper presents methods for the actuation, measurement, and control of a magnetic resonance imaging- and radiation-compatible single-axis translatory actuation system. As an exemplary demanding use case, the axis is developed for a robotic phantom for evaluating emitted radiation doses of radiotherapy devices. For this, the robot has to follow given three-dimensional trajectories of patients' movements with an accuracy of 200 µm. For enabling use of magnetic resonance imaging, actuation of the robot is realized by hydraulic transmission without any metal parts or electrical components at the imaging side. The hydraulic axis is developed, built-up, and tested. In order to compensate for deviations from the targeted actuation trajectory resulting from tolerances, friction, and non-linearities in the system, a combination of photogrammetric measurement and iterative learning control is applied. The developed photogrammetric system is capable of determining the robot's position with systematic errors of 35 µm and stochastic errors of 0.3 µm. Different types of iterative learning control methods are applied, parameterized, and tested. With this, the hydraulically actuated axis is able to follow given trajectories with maximum errors below 130 µm. [ABSTRACT FROM AUTHOR]

Plasma actuators have been proposed as a tool to produce hydrodynamical effects in the boundary layer of aerodynamical flows. We have analyzed some properties of these systems using suitable plasma diagnostics based on the emissivity characteristics of such plasmas. The direction and the velocity of propagation of the ionizing wave spreading on the dielectric surface were measured (in the 100–200 km/s range), and it was demonstrated that it behaves like a cathode-directed streamer. The averaged electron temperature (4–5 eV) and the reduced field strength (E/N ≈ 6 × 1019 V·m2) of the ionizing wave switching the discharges on were measured, too. [ABSTRACT FROM AUTHOR]

In the field of adaptive building technologies, this research introduces the development of a self-regulating solar shading actuator that utilizes the thermal shape memory effect. The study focuses on addressing the actuator's performance under diverse environmental conditions. Thermal simulations were carried out during the development of the individual components of the actuator and for the prediction of specific switching temperatures. The investigation includes an analysis of the sunshade's response to varying environmental conditions, emphasizing its effectiveness on clear summer days and identifying challenges during overcast periods. The critical coordination between the solar collector and the shape memory alloy (SMA) wire is examined, shedding light on the impact of SMA temperature dynamics on the actuation performance. Through the integration of simulation data and real-world measurements, the study validates the thermal model for the solar collector, establishing the robustness of the system's operation. This research work contributes significantly to the development of intelligent actuators and outlines the importance of validation of SMA-based applications under real conditions. [ABSTRACT FROM AUTHOR]

When developing IoT devices, technologies that automatically plug and play sensor/actuator into the device have been studied. They are the IEEE1451 standard, ETRI standard, and our techniques. There are studies that have qualitatively analyzed each characteristic, but none have quantitatively compared and analyzed them. The problem is that the cost analysis is complicated because the Plug & Play techniques include standard system development, sensor/actuator module development, and application development. In this paper, Platform based Cost Analysis Scheme was proposed, and the cost of each method was analyzed based on this. For cost analysis, a number of experts estimated the development complexity and analyzed the cost based on the national standard cost table. As a result, it was shown that the cost of our techniques was the smallest. [ABSTRACT FROM AUTHOR]

Optogenetics is a powerful approach in neuroscience research. However, other tissues of the body may benefit from controlled ion currents and neuroscience may benefit from more precise optogenetic expression. The present work constructs three subcellularly‐targeted optogenetic actuators based on the channelrhodopsin ChR2‐XXL, utilizing 5, 10, or 15 tandem repeats (TR) from mucin as N‐terminal targeting motifs and evaluates expression in several polarized and non‐polarized cell types. The modified channelrhodopsin maintains its electrophysiological properties, which can be used to produce continuous membrane depolarization, despite the expected size of the repeats. This work then shows that these actuators are subcellularly localized in polarized cells. In polarized epithelial cells, all three actuators localize to just the lateral membrane. The TR‐tagged constructs also express subcellularly in cortical neurons, where TR5‐ChR2XXL and TR10‐ChR2XXL mainly target the somatodendrites. Moreover, the transfection efficiencies are shown to be dependent on cell type and tandem repeat length. Overall, this work verifies that the targeting motifs from epithelial cells can be used to localize optogenetic actuators in both epithelia and neurons, opening epithelia processes to optogenetic manipulation and providing new possibilities to target optogenetic tools. [ABSTRACT FROM AUTHOR]

An adaptive finite-time composite control (AFTCC) scheme is designed for the pitch angle trajectory tracking control of Underwater Glider (UG) with actuator physical constraints, uncertain dynamics and external disturbances. Firstly, a novel nonsingular fast terminal sliding mode control (NFTSMC) law is designed that can avoid singular problems, significantly reduce chattering, and achieve finite-time convergence of the system states. Secondly, a novel fixed-time extended state observer (FxTESO) is established to estimate the pitch angular velocity and lumped disturbances within a fixed time. Furthermore, a novel adaptive fixed-time saturation compensation system (AFxTSCS) is proposed to mitigate the effect caused by actuator saturation, and it can adjust the parameter adaptively when the actuator is in saturation or out of saturation. Finally, the AFTCC scheme, which is based on the NFTSMC framework and combines FxTESO and AFxTSCS, is designed to achieve the pitch angle trajectory tracking of UG, and the finite-time convergence of the whole closed-loop system is proved by the Lyapunov stability theory, and the simulations verify the availability and superiority of the proposed AFTCC scheme. • A simplified underwater glider model is established. • A novel FxTESO is constructed to estimate lumped disturbances. • A novel AFxTSCS is designed to mitigate the effect caused by actuator saturation. • An AFTCC scheme is designed to track the pitch angle of underwater glider. [ABSTRACT FROM AUTHOR]