Velocity Feedback Research Articles

Active vibration control for rotating machines with current-controlled electrodynamic actuators and velocity feedback of the machine feet based on a generalized mathematical formulation

AbstractA theoretical analysis regarding active vibration control of rotating machines with current-controlled electrodynamic actuators between machine feet and steel frame foundation and with velocity feedback of the machine feet vibrations is presented. First, a generalized mathematical formulation is derived based on a state-space description which can be used for different kinds of models (1D, 2D, and 3D models). It is shown that under special boundary conditions, the control parameters can be directly implemented into the stiffness and damping matrices of the system. Based on the generalized mathematical formulation, an example of a rotating machine—described by a 2D model—with journal bearings, flexible rotor, current-controlled electrodynamic actuators, steel frame foundation, and velocity feedback of the machine feet vibrations is presented where the effectiveness of the described active vibration control system is demonstrated.

Instrumented assessment of lower and upper motor neuron signs in amyotrophic lateral sclerosis using robotic manipulation: an explorative study

BackgroundAmyotrophic lateral sclerosis (ALS) is a lethal progressive neurodegenerative disease characterized by upper motor neuron (UMN) and lower motor neuron (LMN) involvement. Their varying degree of involvement results in a clinical heterogenous picture, making clinical assessments of UMN signs in patients with ALS often challenging. We therefore explored whether instrumented assessment using robotic manipulation could potentially be a valuable tool to study signs of UMN involvement.MethodsWe examined the dynamics of the wrist joint of 15 patients with ALS and 15 healthy controls using a Wristalyzer single-axis robotic manipulator and electromyography (EMG) recordings in the flexor and extensor muscles in the forearm. Multi-sinusoidal torque perturbations were applied, during which participants were asked to either relax, comply or resist. A neuromuscular model was used to study muscle viscoelasticity, e.g. stiffness (k) and viscosity (b), and reflexive properties, such as velocity, position and force feedback gains (kv, kp and kf, respectively) that dominated the responses. We further obtained clinical signs of LMN (muscle strength) and UMN (e.g. reflexes, spasticity) dysfunction, and evaluated their relation with the estimated neuromuscular model parameters.ResultsOnly force feedback gains (kf) were elevated in patients (p = 0.033) compared to controls. Higher kf, as well as the resulting reflexive torque (Tref), were both associated with more severe UMN dysfunction in the examined arm (p = 0.040 and p < 0.001). Patients with UMN symptoms in the examined arm had increased kf and Tref compared to controls (both p = 0.037). Neither of these measures was related to muscle strength, but muscle stiffness (k) was lower in weaker patients (p = 0.012). All these findings were obtained from the relaxed test. No differences were observed during the instructions comply and resist.ConclusionsThis findings are proof-of-concept that instrumented assessment using robotic manipulation is a feasible technique in ALS, which may provide quantitative, operator-independent measures relating to UMN symptoms. Elevated force feedback gains, driving larger reflexive muscle torques, appear to be particularly indicative of clinically established levels of UMN dysfunction in the examined arm.

Neural Network Adaptive Inverse Control of Flexible Joint Space Manipulator Considering the Influence of Gravity

With the aim of correcting the problem of trajectory tracking control of a flexible joint space manipulator in environments with different gravity, a neural network adaptive inverse control algorithm based on singular perturbation theory is proposed to resist the disturbance caused by system uncertainty. Firstly, the dynamic model of a flexible joint space manipulator with the influence of gravity is established, and then the system is divided into a fast subsystem and a slow subsystem using singular perturbation theory. The velocity feedback control rate is designed for the fast subsystem to suppress the elastic vibration caused by the joint flexibility. For the slow subsystem, the uncertain term and known term are separated by the inverse control algorithm, where the uncertain term is approximated online by the RBF neural network, and the robust control rate is designed to compensate for the approximation error. The simulation results show that the control method can not only effectively reduce the high-frequency vibration caused by the flexible joint but also resist the system disturbance so that a good track control effect is achieved.

Active vibration control of metal foam reinforced agglomerated graphene nanoplatelets nanocomposite truncated conical shells with piezoelectric layers

This study examines active vibration control (AVC) in a truncated conical shell composed of metal foam reinforced with agglomerated graphene nanoplatelets and integrated with piezoelectric layers functioning as sensors and actuators. Both complete and partial agglomeration states are considered based on the Eshelby–Mori–Tanaka approach, and the mechanical properties of the porous core are characterized using a closed-cell metal foam model. The governing equations of motion are derived using Hamilton’s principle, based on the two-dimensional axisymmetric elasticity theory, and solved through the finite element method coupled with the Newmark method. Vibration mitigation is achieved using a fractional-order fuzzy proportional–integral–derivative (PID) controller. A comprehensive parametric study is conducted, examining the effects of geometric dimensions, various boundary conditions, reinforcement parameters (including weight fraction, distribution patterns, and agglomeration parameters), and porosity parameters (including pore size, and porosity pattern) on the vibration properties of the shell. Numerical simulations are performed to assess the effectiveness of the proposed AVC system in reducing structural vibrations compared to a constant velocity feedback control approach. The velocity feedback controller reduced central deflection from 12.65 to 5.089 μ m , while a fractional-order fuzzy PID controller further improved it to 2.348 μ m , representing a 53.86% enhancement over the velocity feedback controller.

МЕТОДИКА ЕКСПЕРИМЕНТАЛЬНИХ ДОСЛІДЖЕНЬ СПРОЩЕНОЇ МОДЕЛІ БПЛА ТИПУ БІКОПТЕР

Modern aircraft are usually statically unstable objects. Due to this, increased maneuverability and controllability is achieved. One of the promising directions is the development and implementation of UAVs of the bicopter or convertible type. Their movement is provided by two screw electric drives. The non-identity of the engine parameters and the peculiarities of the movement of UAVs of this type cause special requirements for the control systems. To ensure sustainability, modeling and conducting research with the help of various tools is necessary. The most available models of unstable movements are pendulum devices of various types, which allow studying stabilization processes. The purpose of the work is to use a computer stabilization system of a simplified bicopter UAV model by changing the thrust of the engines. The tasks of the work are: development of a computer stabilization system for the angle of pitch or roll, creation and verification of stabilization algorithms on a laboratory bench using an ARDUINO controller, research of the functional capabilities of angular stabilization circuits. The object of the study: a computer control system of an aircraft that performs the task of stabilizing a UAV. Subject of research: processes of stabilization of the angular position of a simplified bicopter model. When performing the work, a control law using angular and angular velocity feedback was chosen. A variant of aircraft stabilization when using engine thrust control is proposed. The control law of the computer stabilization system, which is implemented on the ARDUINO controller, was selected and tested. The applied value of the work is the further use of the obtained results in modern samples of bicopters.

Robust adaptive impedance control of coordinated electrically driven robots: An engineering application for the (p,q)-analogue of Bernstein-Stancu operators

Function approximation techniques have emerged as influential mathematical tools for designing compliant motion controllers capable of managing objects using multiple electrical manipulators without the need for exact models. However, their effectiveness often relies on having access to velocity signals, which may not always be practical in real-world situations. This paper introduces an observer-based robust adaptive impedance control strategy that employs the (p,q)-analogue of Bernstein-Stancu operators as uncertainty estimators to tackle uncertainties in collaborative multiple electrical manipulators. This approach leverages visual task-space information and doesn’t depend on velocity feedback, enhancing cost-effectiveness and applicability in practical robotic systems. The lumped uncertainty is first modeled by this operator. The adaptation laws, derived from stability analysis, are then employed to tune its coefficients, which are not presented in the previous literature. By applying the Lyapunov lemma, the paper ensures that error signals in the controlled system are uniformly ultimately bounded (UUB). The suggested controller is evaluated in a system featuring two arms managing a rigid load. Simulation results showcase the effectiveness and versatility of the proposed approach. The outcomes are also compared with two advanced approximation techniques to demonstrate the precision and effectiveness of the suggested controller design.

Time-delay feedback control on vertical vibration of maglev train under unsteady aerodynamic force

The stability and safety of maglev trains are significantly affected by unsteady aerodynamic forces during high-speed operation. In this paper, we employ a time-delay feedback control strategy to suppress the nonlinear vertical vibrations of maglev train under periodic unsteady aerodynamic force. Firstly, the amplitude-frequency response equation of the maglev vehicle is derived using the multiple scales method, and the stability of the steady-state solutions is determined. Then, the influences of velocity feedback gain coefficient and velocity time delay on the nonlinear vibrations of the maglev vehicle are investigated. The optimal value range of the time delay is identified. The results demonstrate that the time delay feedback control can effectively suppress the nonlinear vibration of maglev vehicles and enhance their operational stability under the premise of reasonable selection of time delay parameters. The theoretical research presented in this paper can serve as a theoretical reference for the design, improvement, and optimization of control systems for high-speed maglev trains.

Comparison of active and passive vibration control techniques for electric drive power electronic subsystem: Experimental validation

Reducing vibration and noise from power electronics components is vital for enhancing the performance and acceptance of electric vehicles, emphasizing the need for effective mitigation strategies in sustainable transportation. This paper compares passive and active vibration techniques, with a specific focus on utilizing particle damping for passive vibration control. The method achieves vibration reduction through viscoelastic deformation and friction resulting from the movement and collisions of granular material within the cavity. This contribution outlines diverse design strategies for integrating particle dampers into power electronic components. The active control approach, operating typically in the 50 Hz to 1200 Hz frequency range, can concurrently support passive noise treatments. Piezoelectric ceramics serve as both actuators and sensors in active noise reduction. Following the identification of dominant mode shapes, appropriate actuator and sensor positions are chosen. The control problem of the smart system is then addressed, opting for a velocity feedback control algorithm in a real collocated design. This algorithm computes input signals for actuators bonded to the outer surface, achieving significant active damping effects. Lab-tested techniques are validated in real-world conditions with a full-scale electric-drive toolkit, affirming their efficacy in reducing vibration and noise and underscoring their potential for implementation in electric vehicles.

Exploring the validity of perceived velocity in lower-limb resistance exercises with a cluster-set configuration

This feasibility study aimed to explore the relationship between mean propulsive velocity (MPV) and a scale of perceived velocity (SPV) in back-squat and deadlift exercises performed with heavy loads during a cluster-sets resistance training (CS-RT). Twelve resistance trained males (24.1[2.94] years; 80.7[9.05] kg; 172[4.7] cm; 19.1[6.17] %BF; 4.71[2.72] years of training experience) participated. Participants visited the laboratory three times, spaced 72 to 96 hours. Load-velocity profiles for each exercise were measured in first visit. During the second and third visits, participants engaged in CS-RT sessions with different intra-set rest period (20 vs 40 seconds, randomly), and consisted of three sets of squat and deadlift exercises at 80%1-RM. Each set concluded upon reaching a 10% velocity loss on two occasions. Bayesian Pearson correlation coefficients (r), 95% credible intervals (95%CrI) and Bayes factors (BF10) were computed to assess the relationship between variables. A low positive correlation was observed between MPV and SPV in deadlift (r=0.368, 95%CrI [0.144, 0.544]), with strong evidence supporting the alternative hypothesis (BF10=20.7). Interestingly, moderate correlation values were observed in the 40-second CS-RT configuration (r=0.47, 95%CrI [0.144, 0.544]) and in the first set of the deadlift (r=0.44, 95%CrI [0.118, 0.654]). Conversely, a negligible Bayesian correlation was identified for squat (r=0.101, 95%CrI [-0.132, 0.319]), with substantial evidence favoring the null hypothesis (BF10=0.208). In conclusion, a positive correlation between MPV and SPV in deadlift during a CS-RT configuration, indicating potential utility for perceived velocity. However, velocity feedback prior SPV use and validity for squatting warrants further investigation. Keywords: Strength training, Perception, Powerlifting, Physical performance, Cluster training.

Control of a building system with sudden nonlinearity using the sliding mode technique

In civil engineering application such as the seismic resistant structural design, a building system often enters into its nonlinear range to minimize the force transfer to the superstructure. An ideal control design should enhance the usefulness of the nonlinear behavior by diminishing its adverse effects at a minimal control input. This study developed a unified feedback mechanism based on the sliding mode control approach that fostered the multiple selected modal control of a structural system undergoing linear and nonlinear stages of hysteretic deformations. The ideal sliding surface for controlling a specific mode was designed based on the interaction characteristics between two modes at two different stages of deformation. An ′ S′ type functional form of the control force was developed on either side of the sliding surface based on the velocity feedback of the system by ensuring reachability to the ideal sliding surface. To demonstrate the effectiveness of the adopted control, a five-story shear building with uniform mass and initial stiffness distribution with concentrated nonlinearity at the base column was considered under 10 earthquake excitations. The system was studied under the proposed control along with the uncontrolled system. In addition to the adopted control, a popular and existing LQG control technique was also implemented based on the equivalent linearized structural system for comparison. The adopted control provided the desired performance of the structural system while keeping the effectiveness of the system’s nonlinearity under earthquake excitations. Considering the system’s responses and the input control force, the efficiency of the adopted mechanism outperformed the LQG control, which was found to amplify the unfavorable effects of the system’s nonlinearity.

Vibrational stability improvement of a mirror system using active mass damping.

Addressing the demand for high stability of beamline instruments at the SHINE facility, a high stability mirror regulating mechanism has been developed for mirror adjustments. Active mass damping was adopted to attenuate pitch angle vibrations of mirrors caused by structural vibrations. An internal absolute velocity feedback was used to reduce the negative impact of spillover effects and to improve performance. The experiment was conducted on a prototype structure of a mirror regulating mechanism, and results showed that the vibration RMS of the pitch angle was effectively attenuated from 47 nrad to 27 nrad above 1 Hz.

Research on high-precision encoder based on optical-magnetic combination structure to measure absolute angle

As a kind of sensor for real-time feedback and dynamic monitoring of angular velocity and angular displacement of the system, the common photoelectric encoder is widely used in many fields such as new energy electric vehicles, servo closed-loop control systems, industrial control, security monitoring. In order to improve the resolution and accuracy, a kind of optical and magnetic combined encoder which combines photoelectricity and multi-pole magnetoelectricity is designed in this paper, where the light-blocking disk of photoelectric sensor is designed according to the pseudo-random sequence, and the photoelectric coding is used to determine the magnetic interval of multi-pole. The absolute angle is calculated according to the number of multiple circles plus the angle of single circle. The experimental results at different temperatures (−40 °C∼100 °C) show that the accuracy of the proposed combined encoder can reach ±0.08°, which is improved by 0.37° compared with that of the single-pole encoder. Finally, the combined encoder was applied to the pan-tilt-zoom (PTZ) camera of a video surveillance enterprise, and the experiment showed that its repeated positioning accuracy reached ±0.02°, which is greatly improved compared with single-pole encoder.

Design of hybrid controller for broadband vibration isolation with active negative stiffness and ground-hook

This paper presents a novel hybrid control strategy that integrates active negative stiffness (ANS) with the ground-hook principle, aiming to enhance the vibration isolation system’s performance across both low and high-frequency ranges. Firstly, to improve vibration isolation performance, this study analyzes the existing ANS model. It identifies key factors affecting ANS stability and proposes a control parameter adjustment scheme based on stability conditions. This approach effectively refines ANS control theory and provides theoretical support for the application of ANS by ensuring stability. Secondly, addressing the limitations of ANS in high-frequency vibration isolation, this study proposes targeted solutions based on the ground-hook principle. While ANS excels in low-frequency isolation, this work tackles its shortcomings to enhance high-frequency vibration isolation. These solutions include the implementation of relative velocity feedback (RVFB) control and absolute velocity feedforward (AVFF) control to enhance high-frequency vibration isolation performance, and AVFF exhibits superior advantages over RVFB. Furthermore, the stability of different control strategies is analyzed. The findings reveal that sky-hook significantly enhances the control stability margin of the ANS loop, while RVFB decreases it, with AVFF having a minimal impact. Finally, comprehensive experiments validate a significant enhancement in both low and high-frequency vibration isolation performance, providing robust evidence for the practical engineering application of the vibration isolation system.

Advanced vibrant controller results of an energetic framework structure

Abstract This research shows the influence of a new active controller technique on a parametrically energized cantilever beam (PECB) with a tip mass model. This article remains primarily concerned with regulating the system’s response using a novel control mechanism. This study describes a novel control mechanism called the nonlinear proportional-derivative cubic velocity feedback controller (NPDCVFC). The motivation of this article is to design a novel control algorithm in order to mitigate the nonlinear vibrations of a parametrically energized cantilever beam with a tip mass model. The proposed controller NPDCVFC incorporates nonlinearly second- and first-order filters into the system. The system is governed by one nonlinear differential equation having both quadratic and cubic nonlinearities within the parametric force. The controller’s efficiency in reducing framework vibrations, managing nonlinear bifurcations, and calming unstable motion is evaluated using numerical simulations of instantaneous vibrations. The perturbation technique is beneficial for solving the current model under the proposed worst resonance case ( Ω ˆ p = 2 ω ˆ 0 ) \text{(}{\hat{{\Omega }}}_{\text{p}}=2{\hat{{\omega }}}_{0}) . In order to choose the optimal controller, we have also added three more controller approaches to the configuration. Integral resonant control, positive position feedback, and nonlinear integral positive position feedback are the three controller approaches that are applied to the structure under consideration. We determine that the NPDCVFC as a new controller is the most effective for lowering the high vibration amplitudes. Over the investigated model, all numerical results were performed using the MATLAB 18.0 programmer software. The stability analysis and the effects of various elements on the controlled structure have been investigated. A comparison with recently published works of a comparable model has also been prepared. Experiment capacities for a PECB with a tip mass are obtainable to validate the results, and they demonstrate good agreement with analytical and numerical results.

Control stability analysis of dynamic model with time delay for quadrotor UAV

For the first-order unstable object with time delay, the PD control parameter tuning method based on the traditional definition lacks consideration of the lower boundary of amplitude margin, resulting in a certain deviation between the result and the reality. In this paper, through analyzing the control loop of quadrotor UAV (QUAV), the integral link is moved from the controlled object to the controller, and the QUAV becomes a first-order unstable object, realizing the conversion of PD to PI in the hovering state. The system stability margin remains unchanged, and the position and attitude control objectives can be realized synchronously. By means of parameter setting method, the upper boundary of stability margin is obtained. Pade approximation is carried out for the time delay link, and then the lower margin of the amplitude margin is deduced according to Routh stability criterion, so as to obtain a more accurate reachable stability margin region. To avoid the high gain feedback of attitude angular velocity of QUAV, a numerical analytical setting formula for PD attitude control is derived to meet the requirements of gain and phase margin. The graph shows that the reachable region obtained by the strict definition of stability margin analysis decreases significantly. The proposed method can not only give the reachable region intuitively, but also give the tuning formula of the control parameters concisely, which has important engineering application value.

Vibration control of membrane structures by piezoelectric actuators considering piezoelectric nonlinearity under strong electric fields

Membrane structures, which are widely used in aerospace and civil engineering, are susceptible to large amplitude vibrations due to their low structural damping and high flexibility, leading to the degradation of their working performance. Strong electric fields are commonly needed for piezoelectric actuators to control larger amplitude vibration of membrane structures. However, the effect of piezoelectric nonlinearity due to strong electric fields on the control performance of membrane structures is still underexplored. Given the importance of piezoelectric nonlinearity due to strong electric fields, the present study aims to investigate the vibration control performance of piezoelectric actuators for membrane structures. First, based on the piezoelectric nonlinear constitutive equation, the actuation equation of the piezoelectric actuator is generated. Then, following D′Alembert's principle, a nonlinear dynamic control model of membrane structure containing actuation force is derived. Finally, active vibration control based on velocity feedback algorithms is realized. The results show that the predicted strain without considering the piezoelectric nonlinearity is 80 % smaller than the finite element structure at 500 V. Meanwhile, the errors of Root Mean Squared (RMS) control displacement without considering the piezoelectric nonlinearity are more than 24 % when vibration amplitudes achieve 10 % of the membrane thickness. The developed model provides theoretical implications for active vibration control of flexible structures with piezoelectric actuators in strong electric field environments.

On the ambipolar diffusion formulation for ion-neutral drifts in the non-negligible drift velocity limit.

The ambipolar diffusion approximation is used to model partially ionized plasma dynamics in a single-fluid setting. To correctly apply the commonly used version of ambipolar diffusion, a set of criteria should be satisfied including the requirement that the difference in velocity between charges and neutral species (known as drift velocity) is much smaller than the thermal velocity, otherwise the drift velocity will drive a non-negligible level of further collisions between the two species. In this paper, we explore the consequences of relaxing this assumption. We show that a new induction equation can be formulated without this assumption. This formulation reduces to the ambipolar induction equation in the case the drift velocity is small. In the large drift velocity limit, the feedback of the drift velocity on the collision frequency results in decreased diffusion of the magnetic field compared with the standard ambipolar diffusion approximation for the same parameters. This has a natural consequence of reducing the frictional heating that can occur. Applying this to results from flux emergence simulations where the expansion of the magnetic field leads to strong adiabatic cooling of the partially ionized chromosphere resulted in a noticeable reduction in the magnitude of the predicted drift velocities. This article is part of the theme issue 'Partially ionized plasma of the solar atmosphere: recent advances and future pathways'.

Active layer damping of bi-directionally tapered functionally graded sandwich plates with 1-3 piezoelectric composites

This article investigates the effect of smart damping on bi-directionally tapered functionally graded sandwich plates. The substrate comprises FG material on both sides of the core of either soft herex or ceramic material. The viscoelastic layer of ALD is restrained, while the compelling layer consists of 1-3PZC. The finite element formulation developed incorporates layer-wise and first-order-shear-deformation theory. The plate’s damping is actively controlled using velocity feedback control incorporating piezoelectric patches. The effects of various parameters of taper ratio and patch positions on vibration control are investigated. The efficacy of the ALD in improving the structural performance of plates is investigated.

Finite-time consensus control of second-order multi-agent systems with input saturation constraint

A novel finite-time consensus technique is derived for second-order linear multi-agent systems with input saturation constraints. The hyperbolic tangent–based saturation function is presented for achieving input saturation while reducing the chattering issue of classical saturation functions. The leader-following consensus controller with a single saturation function is constructed to address the issue of saturation level partition between position feedback and velocity feedback. Theoretically, the property of finite-time consensus, bounded input, and smoothness of a closed-form system are proved by the Lyapunov theory in detail. Numerical simulations are conducted to exhibit the effectiveness of the proposed method fully.

Active vibration control of piezoelectric multilayers FG‐CNTRC and FG‐GPLRC plates

AbstractThis study investigates the active vibration control of multilayer Functionally Graded Carbon NanoTube Reinforced polymer Composite (FG‐CNTRC) plates and multilayer functionally graded graphene platelets reinforced polymer composite (FG‐GPLRC) plates covered with a piezoelectric layer (PZTG1195N) serve as both actuators and sensors. The plate's heart is supposed to be reinforced nonlinearly using both types of reinforcement. Active vibration control of plates under uniform load was achieved by utilizing a velocity feedback control algorithm with a specific gain value. The finite element method is employed to analyze both the static and dynamic behavior of a square plate discretized into 9‐node quadratic finite elements with 5 ° of freedom per node. The material properties are assumed to change across the thickness direction following a power law distribution, exhibiting various patterns: Uniform Distribution (UD), as well as Functionally Graded types X, O, and A (FG‐X, FG‐O, and FG‐A). The geometrical nonlinear equations are solved by the Newmark integration method. This work begins by validating the natural frequencies of a Functionally Graded (FG) composite plate reinforced with four different distributions of Nano‐filler and then aims to show the effect of the nonlinear distribution of nanofillers on the plate's stiffness. The Results obtained after the execution of a developed code highlight the significance of employing a nonlinear distribution of nanofillers to attenuate vibrations.Highlights FG composite and sandwich plates reinforced with GPLs and CNTs. Effect of nonlinear nanofillers distribution of reinforcement on free and forced vibration. The ability of the nonlinear distribution of nanofillers to attenuate forced vibrations.