Adjustable Damping Research Articles

Reprint of: Physical modeling for digital twin of Continuous Damping Control damper

Continuous Damping Control (CDC) damper is a kind of active damper with adjustable damping coefficients, which has a broad application prospect for vibration attenuation in robots and manufacturing systems. To develop a digital twin of CDC damper for monitoring its working conditions, it is necessary to develop a physical model describing the characteristics of CDC damper. However, the existing physical models of CDC damper have some disadvantages such as expensive computing costs and low accuracy, which make it difficult to apply them in the digital twin. In order to solve these issues, this paper proposes a hybrid model which can accurately describe the physical characteristics of CDC damper by combining a lumped parameter model and a neural network model. First, the physical characteristics of a CDC damper are measured on a test rig under harmonic excitations and random excitations. Then the modeling and parameter identification methods for hybrid models are proposed to obtain model parameters. Finally, the output force of the CDC damper under random excitation is calculated using the hybrid model, and the accuracy of the hybrid model is validated after comparing the calculated results with the measured results. The proposed hybrid model has high accuracy and low computational cost, and is applicable to developing digital twins of CDC dampers which require high calculation accuracy and efficiency.

Intelligent vibration control for ultra-high-speed elevators: A type 2 variable universe fuzzy neural network method with input saturation

When elevators accelerate to ultra-high speed, the horizontal vibration suppression is significantly challenged by the complex coupled excitation and uncertain time-varying parameters. Therefore, this paper proposes an intelligent control method with type 2 variable universe fuzzy neural network considering input saturation. Firstly, considering the multilevel relationship of the guide rails, guide shoes, frame and car, a horizontal vibration dynamic model is constructed. To improve the tolerance and adaptability of the control system to the uncertain parameters, the type 2 variable universe fuzzy control is used as the main controller. The discourse of universe is adjusted by the T-S fuzzy neural network, and the anti-saturation controller is designed to compensate for the over-saturation problem aggravated by the networks. The non-parametric inverse model of intelligent adjustable dampers represented by the magnetorheological damper is constructed to accurately calculate the ideal output damping force. The effectiveness of the proposed control method is verified by the elevator experimental data and the bidirectional gas-solid coupling aerodynamic excitation. The results show that the proposed intelligent control method can significantly improve the mean values, peak values and comfort indexes of the horizontal vibration acceleration and tilt angle acceleration of the elevator car. The research provides a new intelligent control scheme for high-speed/ultra-high-speed elevators and other similar vibration suppression systems.

Physical modeling for digital twin of Continuous Damping Control damper

Continuous Damping Control (CDC) damper is a kind of active damper with adjustable damping coefficients, which has a broad application prospect for vibration attenuation in robots and manufacturing systems. To develop a digital twin of CDC damper for monitoring its working conditions, it is necessary to develop a physical model describing the characteristics of CDC damper. However, the existing physical models of CDC damper have some disadvantages such as expensive computing costs and low accuracy, which make it difficult to apply them in the digital twin. In order to solve these issues, this paper proposes a hybrid model which can accurately describe the physical characteristics of CDC damper by combining a lumped parameter model and a neural network model. First, the physical characteristics of a CDC damper are measured on a test rig under harmonic excitations and random excitations. Then the modeling and parameter identification methods for hybrid models are proposed to obtain model parameters. Finally, the output force of the CDC damper under random excitation is calculated using the hybrid model, and the accuracy of the hybrid model is validated after comparing the calculated results with the measured results. The proposed hybrid model has high accuracy and low computational cost, and is applicable to developing digital twins of CDC dampers which require high calculation accuracy and efficiency.

Impulse power detection for fusion power supply based on cascaded quasi-proportion resonance

Megawatt power impact frequently occurs during experiments on magnetic confinement fusion devices. This power impact, which shows the features of high amplitude, rapid change, and strong randomness, threats to the stable operation of fusion devices when achieving long-pulse high temperature conditions. To more effectively handle such power impact, the precise and real-time detection of impulse power is indispensable. Aiming at the issue, the quasi-proportion resonance (QPR) algorithm based on adjustable damping factor is developed, which realizes good extraction and high-speed response performance. Combined with the reference phase angle of grid voltage, the active and reactive power can be further divided. Considering the harmonic power with various frequencies included in impulse power, the cascaded quasi-proportion resonance (CQPR) detection strategy is proposed, which compensates for the deficiency that QPR is unable to handle multi-frequency impulse power. Finally, the validity and stability of CQPR algorithm are proved by MATLAB and experiments with Digital Signal Processing (DSP) platform.

Comparison of Vehicle Suspension Dynamic Responses for Simplified and Advanced Adjustable Damper Models with Friction, Hysteresis and Actuation Delay for Different Comfort-Oriented Control Strategies

Abstract Throughout the years, many control strategies for adjustable dampers have been proposed, designed to boost the performance characteristics of a vehicle. Comfort control strategies such as Skyhook (SH), acceleration-driven damping or power-driven damping have been tested many times using simulation models of vehicles. Those tests, however, were carried out using simplified damper models – linear or simple bilinear with symmetric characteristics. This article presents the results of examination of the influence of using more complex damper models, with friction, hysteresis and time delay of state switching implemented, on the chosen dynamic responses of a suspension system for excitations in the typical exploitation frequency range. The results of the test are compared with those found in the literature and with the results of simulations performed with a simplified version of the advanced model used. The main conclusion is that friction and hysteresis add extra force to the already existing damping force, acting like a damping increase for all analysed control strategies. The actuation delays limit the effectiveness in a sense of comfort increasing to only some frequencies. The research shows the importance of including the proposed modules in testing for both adjustable and passive dampers.

Active Nodes for Passivity and Finite-Gain Stability of Non-autonomous Networks

This paper studies the role of a class of node systems with adjustable damping coefficients in the node dissipation inequalities, called the active nodes, for achieving passivity and finite-gain stability of network systems with external inputs and outputs. The paper first discusses the relation between the active nodes with passivity-type dissipation inequalities and those with L2-stability-type dissipation inequalities, especially focusing on how to transform one type into the other. Then, the paper proceeds to discuss the graph-theoretic condition on the locations of active nodes to achieve network passivity or finite-gain stability. Thereafter, a method for network reduction by exploiting active nodes is presented. Finally, a human-in-the-loop stabilization problem is solved for a network system by exploiting the results developed in the paper.

THE USE OF ADJUSTABLE DAMPING DEVICES FOR INCREASING TECHNICAL LEVEL OF GROUND ROBOTIC COMPLEXES EQUIPPED WITH A MANIPULATOR

A dynamic model of the manipulator of the robotic complex was developed on the basis of the conducted experimental studies. The concept of determining the dynamic characteristics of the mechanical system is proposed according to the results of the oscillation analysis. The algorithm is supplemented with modules considering possibility of using controlled damping devices. The constituent parts of the model represent the mechanical devices of the manipulator, in particular connections, rotary assemblies and damping devices. The model contains all the connections between the modules, which allows you to study the dynamic parameters during the operation of the mechanism. Differential dependencies for the implementation of the mathematical model, which includes the subsystem of dynamic damping of vibrational oscillations of the manipulator, are proposed. These dependencies reveal the essence of the oscillatory processes of the mechanical system in full. Guided damping devices introduced into the model allow to control parameters in order to increase the accuracy of the mechanism. The mathematical model is implemented via a software module that takes into account the impact working processes that occur in the connections and rotary assemblies of the mechanical system of the robotic complex. The algorithm involves the use of a mechatronic system equipped with feedback sensors to control the manipulator. Controlled damping devices make it possible to increase the technical level and improve the dynamic characteristics of the mechanical system. Damping of oscillations by a mechatronic system with feedback was investigated and the influence of damping of oscillations on accuracy parameters when moving a robotic complex on an uneven surface was determined. The paper presents the results of modeling an adjustable damper as part of a moving mechanical system. The innovative device uses a magnetorheological fluid as a working fluid, which allows you to control it with the help of electrical impulses. The conducted experimental studies made it possible to obtain key indicators and its operating characteristics of the damper. Based on these results, dependencies, which determine the control laws of a damper that uses a magnetorheological fluid, are proposed.

Self‐powered In‐Phase Sensing and Regulating Mechanical System Enabled by Nanogenerator and Electrorheological Fluid

AbstractMechanical system with adjustable stiffness and damping (ASAD) shows great potential in vibration suppression of aircraft, vehicle, precise instrument, etc. However, current ASAD systems consist of power, sensing, and controlling components, which bring huge challenges of system reliability and integrability, and critically limit its application diversity. Herein, we proposed the first strategy for regulating ASAD system that is system simplification, self‐powered and no‐delay by deeply coupling triboelectric nanogenerator (TENG) and electrorheological fluid (ERF). Under the time‐varying mechanical triggering, the local and time correlated output of TENG instantaneously applied on the ERF regulates the entire mechanical system dynamically and “in‐phase”. As an illustration, the resonance of a cantilever system is effectively suppressed naturally without complicated controlling strategy, and the vibration isolating efficiency reaches up to 85.2%. Finally, a mechanical transmission system is demonstrated utilizing a rotary TENG and ERF, excellent soft‐start performance is enabled by this self‐regulating ASAD strategy. This work may provide the opening arsenal of methodologies used in self‐powered and self‐regulating mechanical systems.

Theoretical analysis of vibration protection properties of a single-support suspension under constant and adjustable inelastic resistance in the oscillation cycle

The article presents a theoretical analysis of the vibration protection properties of a single-mass single-support suspension with unregulated and adjustable damping in the oscillation cycle. It was found that, in comparison with unregulated damping, its instantaneous regulation in the oscillation cycle provides a low level and approximate constancy of the vertical accelerations ranges of the sprung mass in the resonant oscillation zone, but causes an abrupt change in acceleration at the moments of damping off when the suspension passes its middle position. Replacing the instantaneous damping shutdown with a smooth one in the area of the middle position of the suspension makes it possible to reduce the resonant frequency by more than 2 times compared to the resonant frequency of an unregulated suspension and reduce the range of vertical accelerations of the sprung mass in the resonant zone by up to 25 % compared to the range of accelerations of the sprung mass on a suspension with optimal instantaneous damping control. Keywords: theoretical analysis, vibration protection properties, single-support suspension, adjustable damping, oscillation cycle

Collision Avoidance for Redundant 7-DOF Robots Using a Critically Damped Dynamic Approach

The presence of collaborative robots in industrial environments requires that their control strategies include collision avoidance in the generation of trajectories. In general, collision avoidance is performed via additional displacements of the kinematic chain that make the robot move far from the objects that are occasionally inserted into its safety workspace. The variability of the coordinates of the collision points inside the safety volume leads to abrupt movements for the robot. This paper presents a general method for smoothing abrupt movements in robots with one degree of redundancy for collision-avoidance trajectories, employing a second-order digital filter designed with adjustable critical damping. The method is illustrated by applying it to a redundant robot with a spherical–revolute–spherical type (SRS-type) kinematic chain, which is a benchmark used to test the algorithms ideated for solving this problem. This paper also presents an alternative algorithm for the inverse kinematics of the SRS-type robot and the computational experiments that show the collision avoidance proposal’s performance and its properties through graphical results.

How to Exploit the Glass Mass for Damping a Building?

The worlds spectacular skylines host tall and slender buildings to create a maximum of office, residential and commercial space on a minimized footprint. These structures need to cope with increasing wind forces at height and are additionally affected by wind-induced vibration due to their lower natural frequencies. The resulting vibrations make users uncomfortable. Therefore, heavy tuned mass dampers are installed in structures and occupy valuable space especially in the costliest top-floors. As an example, Taipei 101’s steel damper is located between the 87th and 91st floor and weights astonishing 660 metric tons. This raises the need for additional reinforcement which increases cost and carbon footprint.Most buildings in expensive metropolises are cladded with remarkable glass facades. Therefore, we asked the question if it was possible to use the existing mass – more specifically the glass mass in a Double‑Skin Facade – to dampen the building’s movement, create a comfortable space for the user, exploit more floor area for the investor and finally to minimize the amount of building material to reduce carbon footprint for society. The idea was realized in a collaborative research effort of TU Berlin, BTU Cottbus-Senftenberg and Josef Gartner GmbH that resulted in a full-scale mock-up of a Double‑Skin Facade. Its outer skin can move laterally on a guide rail system. As the building starts to move, the facade's inner skin remains fixed to the base structure while the outer skin follows the building’s movement in a delayed manner due to its mass inertia. The fixed inner skin and the moveable outer skin are connected by a spring system that is tuned to the first natural frequency of the base structure. During the motion of the facade’s outer skin, the spring system redirects the relative movement and generates a stabilizing force for the base structure in the opposite direction. Additionally, an electrical machine is placed in between to provide an adjustable damping effect for semi-active and passive control. It also serves the purpose of a generator to study the opportunity to harvest energy. The paper shows the structural design options for the novel facade concept in the context of a project review of Double-Skin and Closed-Cavity Facades. The function of a full-scale mock-up, its fabrication and installation are described to show feasibility and ongoing challenges. First test results reveal a close match between theoretical assumptions and the applied testing. This engineering-driven and experimentally validated design opens a new field of architectural options in sustainable facade design which is focused on tuning physical parameters that affect the damping properties of the global structure.

Research on Damping Contribution Rate of Key Parameters of Valve-Controlled Damping Adjustable Damper

Valve-controlled damping adjustable damper has the characteristics of simple structure and adjustable damping, and it has always been a hot research topic. This paper establishes a mathematical model of damping characteristics of the valve-controlled damping adjustable damper and designs the experiment of the damping characteristics of the compression stroke and the recovery stroke. Through simulation and experiment, the accuracy of the mathematical model is verified, and the damping contribution rate of different key parameters under different excitation speeds is analyzed. The results show that the mathematical model of the damping characteristics can well describe the working state of the damper. The damping contribution rate of key parameters under different excitation speeds is obtained. The damping contribution of the constant through-hole diameter decreases gradually after the valve is opened for the first time. With the increase of the excitation speed, the valve plate equivalent thickness and the valve plate maximum limit clearance of the check valve gradually play a major role in the damping contribution rate. The research results can screen out the key parameters, improve the development efficiency of the damper, and provide guidance for the damper design and optimization.

Investigation on energy-regenerative shock absorber with adjustable damping and power for freight wagons

Due to lack of power supply, the onboard monitoring and intelligent devices applied in unpowered freight wagons require manual periodic battery replacement. Converting and utilizing local vibration energy is an effective means to realize the self-power of nearby onboard devices. In this paper, a compact energy-regenerativeshockabsorber with nut-screw transmission and novel unidirectional rotation converter is proposed for harvesting energy from suspension vibration of freight wagons. In addition, an interface circuit with voltage control loop implements the adjustment of system damping and power. With two given policies of control loop reference value, the absorber presents two mechanical characteristics: variable damping and constant damping. The overall system is modelled with dynamic characteristic of diodes considered, and the numerical simulation errors in absorber reaction force and the power obtained by DC/DC are reduced by 48% and 66%. In lab tests, the maximum average efficiencies of DC/DC converter and the whole system are 87.66% and 42.6%. A maximum charging power of 9 W is obtained at the normal suspension vibration excitation, and the average charging power can achieve 87% of that at ideal impedance matching. Meanwhile, the system damping characteristics and power generation capacity under the influence of voltage control loop and external excitation are investigated systematically. By vehicle-track dynamics analysis, the influence law of absorber on freight wagon vibration characteristics is revealed versus different circuit loads. This energy-regenerative damping system possesses adjustable damping and power by the control of circuit load, which will have notable superiority in adapting to the mechanical constraints and power requirements of more engineering application scenarios.

A Novel Theoretical and Practical Methodology for Extracting the Parameters of the Single and Double Diode Photovoltaic Models

Solar Photovoltaic (PV) system is one of the most significant forms of renewable energy resources, and it requires accuracy to assess, design, and extraction of its parameters. Several methods have been extensively applied to mimic the nonlinearity and multi-model behavior of the PV system. However, there is no method to date that can guarantee the extracted parameter of the PV model is the most accurate one. Therefore, this paper presents a unique approach known as Hybridized Arithmetic Operation Algorithm based on Efficient Newton Raphson (HAOA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ENR</sub> ) to experimentally extract the parameters of the single-diode and double-diode PV models at the variability of the climatic changes. Firstly, the objective function is efficiently designed to roughly predict the initial root values of the PV equation. Secondly, the Lévy flight and Brownian strategies are integrated in the four operators of AOA to thoroughly analyze the feature space of this problem. Additionally, the four operators of the AOA is divided into two phases to equilibrium between the exploration and exploitation tendencies. Furthermore, the chaotic map and robust mutation techniques are systematically employed in the beginning and halves of generations to ensure the algorithm can reach globally at few numbers iterations. Finally, a nonlinearly adjustable damping parameter of the Levenberg-Marquardt technique is linked with the NR method to replicate the fluctuation behaviours of the PV models. The experimental findings revealed that the proposed HAOA <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ENR</sub> outperformed all other methods found in the literature, with average RMSE values close to zero values for both PV models.

Study on the Structure and Performance of an Antagonistic Pneumatic Bidirectional Rotary Joint

An antagonistic pneumatic bidirectional rotary flexible joint was developed to improve both safety and environmental adaptability of service robots and associated human interactions. The joint comprises two semicircular rotary actuators with positive and negative symmetrical distributions and a pneumatic brake. As such, it achieves forward and reverse rotations, and its damping and braking are adjustable in real time, enabling it to maintain its position. According to the force/torque balance at the free end of the rotary actuator, the rotation angle static model was established. The relationship between the actuator rotation angle, driving torque, impedance torque, and air pressure was obtained experimentally. The brake airbag was manufactured using additive manufacturing and silicone gel casting technologies. The mathematical model of the braking torque was established next, and the model was verified through experiments. Furthermore, an experimental system was constructed to carry out the air pressure-angle, air pressure-torque, and speed response experiments without the load on the joint. The results have shown that the joint can achieve any position within ± 68.5° when the driving air pressure varies from 0 to 0.30 MPa; the time required to reach the maximum angle was 0.85 s. The joint has shown good adjustable damping characteristics. Lastly, the braking torque reached 4.21 Nm at 0.32 MPa, effectively maintaining the position.

Robust Vibration Control Based on Rigid-Body State Observer for Modular Joints

The vibration caused by resonance modes frequently occurs during acceleration and deceleration of the modular joint integrated with flexible harmonic drive. The conventional equivalent rigid-body velocity method with observer can suppress the residual vibration induced by resonant frequency but has poor robustness to model uncertainties and external disturbances. Moreover, it cannot eliminate the torque ripple caused by the harmonic drive during low-speed uniform motion, reducing the velocity tracking accuracy. Hence, a velocity controller with a rigid-body state observer and an adjustable damper is designed to improve the robust performance and velocity tracking accuracy. The designed rigid-body state observer allows a higher gain so that the bandwidth of the observer can increase, and the equivalent rigid-body velocity can be acquired more accurately. Notably, the high gain observer reduces the sensitivity to model uncertainties and exotic disturbances, especially near the resonant frequency. In addition, the observer combined with an adjustable damper can suppress the residual vibration and torque ripple simultaneously. The proposed method is compared experimentally with a PI method and two other rigid-body velocity methods, such as the conventional equivalent rigid-body observer method and the self-resonance cancellation method, to verify its advantages.

Semi active damping force estimation using [formula omitted] estimators with different sensing configurations

Semi-active suspension systems have become a widespread tool to improve the handling and comfort of vehicles. These systems require adjustable dampers as well as supplementary sensing elements. In addition to displacements and accelerations, some of the best performing approaches require knowledge of the semi active damper force. Since this variable can be difficult and expensive to measure, several estimation methods have been proposed. In this article, two Linear-Parameter-VaryingH∞ (LPV-H∞) filters are developed to estimate the Semi-Active (SA) damper force, considering two different combinations of sensing elements: the first configuration is more expensive, but potentially more accurate and reliable; whereas the second configuration is cheaper and arguably less reliable. Thanks to the use of LPV-H∞ theory, both filters are designed to account for the main nonlinear phenomena of SA dampers (i.e. saturation, hysteresis, etc.), as well as being quadratically stable, robust to the road disturbances and optimized to reduce the estimation error in a specified frequency band. Simulations and experimental data are used to assess the proposed estimators as well as a typical inverse-dynamics estimation approach. The results show that while both of the proposed estimators yield a good degree of accuracy, there are indeed fundamental differences depending on the available sensing elements; a conclusion which could be crucial to appropriately define the instrumentation of semi-active suspension systems.

Variable universe fuzzy control of the wheel loader semi-active cab suspension with multimode switching shock absorber

The aim of this work is to design a variable universe fuzzy control of a wheel loader semi-active cab suspension with damping multimode switching shock absorber. Considering the cost and reliability, a new type of shock absorber, whose adjustable damping characteristics are achieved by just changing the on–off statuses of two solenoid valves, is applied to the wheel loader cab suspension. The vibration model of the wheel loader, which considers the vibration characteristics of the working device, the four-wheel correlated random road excitation, and the engine vibration excitation simultaneously, is established first. Based on the working principle of the target shock absorber, the damping multi-state switching model is also established to reflect the relationship between the damping coefficients and the on–off statuses of two solenoid valves. Then, a variable universe fuzzy damping control strategy, which can determine the optimal switching sequences of the damping modes according to the cab suspension performance indexes, is designed. Finally, simulation analyses were conducted to verify the effectiveness of the proposed control approach of the wheel loader semi-active cab suspension with multimode switching shock absorber.

Damping Performance Analysis of Magnetorheological Damper Based on Multiphysics Coupling

Magnetorheological (MR) damper performance is evaluated only by single-field analysis in the design process, which can easily lead to larger design errors. Based on this, a simulation method of MR damper considering multiphysics coupling was proposed. According to a certain automobile shock absorber requirement, an MR damper suitable for automobile suspension was designed. The mechanical model, electromagnetic field model, flow field model, and structural stress field model of the MR damper were deduced and established. To investigate the damping performance of the MR damper more accurately, the multiphysics coupling simulation model was established by COMSOL software, and coupling analysis of the electromagnetic field, flow field, and structural stress field was also carried out. The static magnetic field characteristics, dynamic flow field characteristics, stress distribution, and dynamic performance of the proposed MR damper under the action of multiphysics coupling were obtained. The simulation results show that the damping force is 1134.6 N, and the damping adjustable coefficient is 9.1 at an applied current of 1.4 A. A test system was established to analyze the dynamic performance of the MR damper, and the simulation results were compared with the experimental results. The results show that the simulated and experimental results have the same change rule. Moreover, the damping force increases with the applied current, and different external excitations have little effect on the damping force. The damper can output appropriate damping force and has a wide adjustable damping range. The experimental results illustrate that the damping force is 1200.0 N, and the damping adjustable coefficient is 10.1 when the current is 1.4 A. The error between simulation and experiment of the damping force and damping adjustable coefficient is only 5.5% and 9.9%, respectively.

Design and analysis of a single adjustable damping force robotic leg working with magnetorheological technology

Aiming at the problems of leg’s huge impact faced by legged robot in running movements, an adjustable damping force robotic leg working with magnetorheological technology was designed. The mechanism of how the magnetorheological damper adjusts the damping force of the robotic leg is analyzed. Based on SLIP model, the dynamic of the robotic leg was established. With Foot contact force, the displacement of the hip joint in the vertical direction and the loss of leg’s energy as the optimization objectives, the optimal damping force at different velocity was obtained by weight optimization algorithm, and the curve of the optimal damping force of the leg varying with the speed of the body is fitted. The cushioning capacity of the leg was simulated and verified at a speed of 4 meters per second, and the results showed that the structure with adjustable damping force meet the requirements of high cushion performance in running movements.