Damping Control Method Research Articles

Development of an Innovative Magnetorheological Gearbox for Positioning Control and Anti-Disturbance of a Robotic Arm

The robotic arm is a critical component of modern industrial manufacturing. However, its positioning performance can be hindered by overshooting and oscillation. External disturbances, including collisions or impacts with other objects, can also affect its accuracy and precision. To resolve this problem, this work integrates a compact magnetorheological (MR) bearing, which is capable of switching between locking and unlocking states utilizing the MR effect, into the gearbox of the actuation system of the robotic arm. This integration enables the gearbox (referred to as the MR gearbox) to exhibit variable damping characteristics. This controllable damping property will play an important role in improving the positioning accuracy by offering additional damping. In this study, the MR gearbox was first designed and prototyped. A characterization test was then conducted to verify its variable damping property. The classic Bouc–Wen model was used to describe the MR gearbox and then a mathematical model was established for the whole robotic arm. Additionally, a new variable damping control method was proposed for further improving the positioning precision and reducing energy consumption. As follows, the positioning and the anti-disturbance performances of the robotic arm system installed with the MR gearbox were assessed through numerical simulations and experimental tests. The result shows that the robotic arm under the new control method achieves reductions of 11.76% in overshoot, 14.73% in settling time, and 26.1% in energy consumption compared to the uncontrolled case under the step trajectory, indicating improved positioning performance.

Additional damping control for multi-terminal AC-DC hybrid system based on reachability analysis

Abstract The application proportion of multi-terminal AC-DC hybrid power distribution systems is constantly increasing. In order to describe the operation status and trajectory of the system and judge whether the system can maintain stable and safe operation, in this paper, the differential algebraic equation is firstly established by mathematical and physical methods for a typical multi-terminal AC-DC hybrid power distribution system. Then, the reachable set in the operation process is analyzed according to the reachability analysis calculation method to judge the stable operation status. An additional damping control method is proposed, which can effectively restrain the negative impedance characteristics of the DC micro-grid and improve the operation stability of the system. Finally, the improvement performance of the control method is verified by combining the reachability analysis results.

Active vibration control in robotic grinding using six-axis acceleration feedback

Industrial robots endure severe vibrations in the grinding process due to factors such as joint flexibility, low damping, and contact force fluctuations. Additionally, the motion control of the robot primarily relies on feedback signals from the motor-side encoders, while lacking motion state feedback from the load side. This exacerbates the robot vibrations, severely compromising the surface quality of the workpieces. To address this problem, an active damping control method for robotic grinding using six-axis acceleration feedback is proposed. This method realizes a simple, reliable, and efficient active vibration control without altering the robot body. A multi-sensor fusion Cartesian space six-axis accelerometer is designed and integrated into the robot end effector, achieving accurate feedback on the robot load side vibration state. The strategy of six-axis acceleration decoupling and principle of the vibration suppression with the acceleration feedback are explained. Compared with conventional sensing schemes, this reduces joint acceleration approximation errors and end vibrations. The robotic grinding experiments are carried out on aeronautic structural parts. Extensive case studies demonstrate that the proposed approach can effectively control the vibration caused by joint flexibility in the robot grinding process, and greatly improve the surface quality of workpieces. This method has great potential application in vibration suppression during robotic grinding and polishing.

OPTIMISED DAMPING CONTROL OF ISLANDED DC POWER SYSTEMS USING STATE FEEDBACK

DC microgrid contains a large number of tightly regulated closed-loop converters, which performance for the constant power loads and may cause stability problem of bus voltage when used as a load since they trend to draw constant power. In order to improve the stability of DC microgrid, this paper proposes a method for stabilization the DC microgrid based on the state feedback. e. In this study, the small disturbance linearised state equation of a DC-power grid with constant power load is derived to estimate the damping characteristics of DC voltage. To enhance the transient voltage stability, a novel DC- voltage damping control method is proposed, where both DC voltage and DC current are used as state feedback variables. Index Terms – DC microgrid; stabilization; islanded mode; constant-power load; PID controller

Seismic Control of Adjacent Liquid Storage Tanks Based on Vibration Barrier Considering Structure-Soil-Structure Interaction

ABSTRACT A new damping control method for the adjacent liquid storage tanks (LSTs) based on vibration barrier (ViBa) is proposed. Considering liquid-solid-soil coupling and structure-soil-structure interaction, a three-dimensional numerical calculation model is established by ADINA. The seismic control effect of ViBa is investigated, and parametric analysis is carried out. The results show that ViBa has a significant control effect on seismic responses and wave height, and the reduction factor of base shear force reaches the maximum value of 49.26%. The larger the seismic intensity, the liquid storage height and the height-radius ratio, the larger the reduction factor of the ViBa.

Resonance Suppression of Multi‐Inverter Systems Based on Global Admittance Reshaping

This paper proposes an active damping control method based on converter‐side current feedback to mitigate the resonance issue in multi‐inverter grid‐connected systems caused by coupling with the grid impedance. The method aims to address the reduction in grid power quality by utilizing an active damping device without modifying the hardware and software of the grid‐connected inverters. By introducing an additional small‐capacity power electronic device in parallel, the proposed method establishes two parallel admittances at the common connection point, creating specific conduction paths for system harmonics and reshaping the overall system admittance. In parallel operation of two photovoltaic grid‐connected inverters with different capacities, the access of the inherent admittance and virtual admittance of the source damper reduces the harmonic distortion rate of the grid‐connected current from 19.81% to 2.04% and from 15.86% to 0.52%, respectively. Simulation results validate the effectiveness and correctness of the proposed strategy.

Active damping control method for suspended gravity offloading system

Active damping control method for suspended gravity offloading system

Small-Signal Stability Analysis and MOSMA-Based Optimization Control Strategy of OWF with MMC-HVDC Grid Connection.

The recent oscillation events in offshore wind farms (OWFs) connected via a modular multilevel-converter-based HVDC (MMC-HVDC) system are developing towards a wider frequency band, which causes complex a small-signal interaction phenomenon and difficulties in the stability analysis and control. In this paper, the wideband dynamic interaction mechanism is investigated based on the impedance analysis method and an improved control strategy using an optimization algorithm is proposed to improve the small-signal stability and reduce the oscillation risks. First, the detailed impedance models of the grid-connected system are established considering the distribution characteristics of the submarine cable, control delay and frequency coupling effect. Then, combined with the active damping control method, the wideband resonance mechanism is analyzed, and the stability constraints of controller parameters are obtained using the impedance stability criterion. Finally, an improved multi-objective slime mold algorithm (MOSMA)-based coordinated optimization control strategy is proposed to enhance the adaptability of the controller parameters and the wideband damping ability of a grid-connected system, which can improve the wideband stability of the system. The simulation and experimental results verify the proposed control strategy.

Power oscillation suppression of multi-VSG based on both consensus and model predictive control

Under the circumstances of multi-VSG, virtual synchronous generator (VSG) control is liable to produce active power oscillation due to the absence of mutual damping, which may lead the power fluctuations more acute that may in turn cause instability problems. This study concentrates on the analysis of power fluctuations and the optimization of mutual damping within multi-VSG systems. By developing a predictive model for VSG, a mutual damping control strategy, which incorporates both Model Predictive Control (MPC) and a consensus algorithm, is proposed. The proposed method primarily employs the MPC model of VSG to calculate the increments active power for system interaction. Subsequently, a consensus algorithm is utilized to exchange the increments active power, which is then superimposed on each VSG to enhance the mutual damping. The stability of both the MPC and the proposed mutual damping control method is ensured using the Lyapunov stability criterion. Furthermore, a gain adjustment function is employed to accelerate convergence of the algorithm and maintain stability even under non-ideal communication. The effectiveness of the theoretical analysis and the proposed method is demonstrated through simulations.

Analysis and Suppression of High-Frequency Resonance for Offshore Wind Power Grid-Connected Converter Considering Cable Capacitance Effect

Large-scale offshore wind farms have become the development trend in wind power generation. Long submarine cables are used to collect electrical energy in the collection networks of offshore wind farms. However, the distributed capacitance of cables cannot be ignored, which makes the impedance of the collection network complex and changeable. It is common to encounter high-frequency harmonic resonance (HFHR) problems when cables interact with wind turbine generators (WTGs). The HFHR may threaten the safe and stable operation of wind turbines. In order to solve this problem, firstly, the impedance of a collection network was constructed. Furthermore, the wind farm collection network was divided into the equivalent wind turbine subsystem (EWTS) and the remaining equivalent wind farm subsystem (REWFS). Then, the mechanism of HFHR was revealed based on the impedance stability analysis method. The effects of cable parameters, the number of connected WTG, and the grid impedance on the HFHR of the interconnected system were also analyzed. Finally, the hybrid damping control method, combining active damping control (ADC) and passive damping control (PDC), was proposed to suppress the resonance. A simulation and experiment were performed to verify the effectiveness of the analysis results and proposed control method.

Reinforcement learning based variable damping control of wearable robotic limbs for maintaining astronaut pose during extravehicular activity.

As astronauts perform on-orbit servicing of extravehicular activity (EVA) without the help of the space station's robotic arms, it will be rather difficult and labor-consuming to maintain the appropriate position in case of impact. In order to solve this problem, we propose the development of a wearable robotic limb system for astronaut assistance and a variable damping control method for maintaining the astronaut's position. The requirements of the astronaut's impact-resisting ability during EVA were analyzed, including the capabilities of deviation resistance, fast return, oscillation resistance, and accurate return. To meet these needs, the system of the astronaut with robotic limbs was modeled and simplified. In combination with this simplified model and a reinforcement learning algorithm, a variable damping controller for the end of the robotic limb was obtained, which can regulate the dynamic performance of the robot end to resist oscillation after impact. A weightless simulation environment for the astronaut with robotic limbs was constructed. The simulation results demonstrate that the proposed method can meet the recommended requirements for maintaining an astronaut's position during EVA. No matter how the damping coefficient was set, the fixed damping control method failed to meet all four requirements at the same time. In comparison to the fixed damping control method, the variable damping controller proposed in this paper fully satisfied all the impact-resisting requirements by itself. It could prevent excessive deviation from the original position and was able to achieve a fast return to the starting point. The maximum deviation displacement was reduced by 39.3% and the recovery time was cut by 17.7%. Besides, it also had the ability to prevent reciprocating oscillation and return to the original position accurately.

Active Damping Control Method for Different Dual-Parallel-SPMSM Systems with Single Inverter

This paper presents a stabilization method for different dual parallel surface permanent magnet synchronous motor (SPMSM) systems with a single inverter. When a single inverter drives two synchronous motors, disturbance can cause a torque difference between the two motors. This can cause the motor's electrical and mechanical resonance. Several damping control methods have been proposed to suppress such resonance. However, such methods consider that the parameters of the two motors are identical. When a single inverter controls two motors with different parameters, the damping control performance deteriorates. Besides, the motor's resonance sound and current ripple increase. To address these problems, this paper proposes a control method for dual-parallel-SPMSM drive systems with a single inverter.

Active Vibration Control Strategy for Online Application in a Range Extender

Noise, vibration and harshness are a big issue for hybrid vehicles especially in range extenders. Traditional vibration control and active damping control are generally used for suppressing vibration. Compared with traditional vibration control, active damping control is more flexible and effective in suppressing vibration. The basic idea of active damping control is controlling electric motor compensating for the torque of engine and reducing the vibration from the source. The reduction of vibration is highly depended on the compensation torque of the electric motor. A differently designed compensation torque has a significant impact on the active damping control effect. In this paper, an active damping control method for online application is proposed. And several kinds of compensation torque are designed for this method. Experiments on vibration performance are conducted to compare the effect of different compensation torque design in reducing vibration. And the results show that the compensation torque in the shape of square wave has potential for reducing vibration in all directions. Finally, a guiding tool for compensation design is proposed by correlation analysis and the relationship between designing factors and vibration is revealed.

A frequency-dependent variable damping control method for base-isolated structures under ground motions with different frequency characteristics

The base isolation technique is commonly adopted to protect important structures from earthquake damages. Typically, a high damping ratio for the base isolation layer is useful in reducing the structure's resonance effect under low-frequency (long-period) ground motions, and a low damping ratio is preferred in minimizing the acceleration response under high-frequency (short-period) ground motions while not causing significant displacement response. To realize optimal control for base-isolated structures under ground motions with different frequency characteristics, the semi-active control is adopted and a frequency-dependent variable damping (FVD) control method based on a transmissibility weighted fast Fourier transform (TWFFT) spectrum is newly proposed. The FVD control method considers the influences of different frequency components of ground motions on base-isolated structures by developing the TWFFT spectrum of the detected ground accelerations. A series of shaking table tests for a base-isolated steel frame structure with semi-active control were carried out to evaluate the effectiveness of the FVD control method. The test results demonstrated that the FVD control method could realize optimal control of the structure under various types of ground motions, and it was more effective than the ON-OFF control method which only considered the dominant frequency characteristics of the ground motions.

An Adaptive Proportional Plus Damping Control for Teleoperation Systems with Asymmetric Time-Varying Communication Delays

Communication delay is an important factor affecting the stability and performance of telerobotic systems. In this paper, a new adaptive proportional damping controller is proposed to improve the stability and performance of the system in the presence of the cases such as asymmetric communication delay, unknown gravity torque, friction torque, and other disturbance torques. The proposed proportional damping control method combines the RBF neural network and adaptive control strategy to compensate for the unknown torque. The stability and robustness of the system are enhanced by adding error-damping items, operator force, and environmental force items. The Lyapunov–Krasovskii functional is employed to analyze and prove the exponential stability and signal boundedness of the closed-loop system. The simulation results verify the correctness of the proposed method, and the comparison with the results of other control methods shows the effectiveness of the designed control strategy.

An Active Damping Control Method for Reduced DC-Link Capacitance PMSM Drives With Low Line Inductance

The power density can be improved and the system cost can be saved in the reduced dc-link capacitance motor drive system. The line inductance can also be diminished to reduce the system volume further. In previous research works, the active damping control methods mainly concentrated on the drive system equipped with a larger line inductor. In this article, a dc-link voltage estimation feedback-based active damping method is proposed to suppress the grid current harmonics and improve the drive system stability with low line inductance. The dc-link voltage ripple caused by the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance is analyzed to evaluate the direct dc-link voltage feedback-based active damping control method. To improve the damping performance, the resonant component of the dc-link voltage caused by the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> resonance could be obtained through the grid current to establish the feedback control loop. The sampling delay should be compensated to improve the control performance. The stability of the drive system is evaluated by the Nyquist plots of the impedance model, and the grid current is also analyzed, which could satisfy the harmonic requirements of IEC-61000-3-2. Experimental results are performed to verify the effectiveness of the proposed method.

Intelligent damping control of renewable energy/hydrogen energy DC interconnection system

Renewable energy DC hydrogen production has become a new development trend. Due to the interaction between the weak damping of DC network and the negative impedance characteristics of power supply of hydrogen production, the actual available power of renewable and hydrogen energy DC interconnection system will be lower than its rated setting value. To solve this problem, this paper proposes an intelligent damping control to realize the rated power operation of hydrogen generation power source and significantly improve the hydrogen generation performance. In this paper, the nonlinear model under typical control strategies is established in order to adapt to different degrees of disturbance, and the damping controller is designed based on state feedback, including feedback control law and damping generation formula. On this basis, an intelligent method of damping control is proposed to support rapid decision-making. Finally, the intelligent damping control method is verified by simulation analysis. It realizes rated power of power supply of hydrogen production by generating only a small amount of damping power and superimposing it on the hydrogen production power.

Power Oscillation Suppression of Multi-VSG Grid via Decentralized Mutual Damping Control

Virtual synchronous generator (VSG) control introduces active power oscillation especially under the condition of multi-VSG. This article proposes a decentralized mutual damping control method that suppresses power oscillation in the multi-VSG grid. The idea is that as the local frequency is greater than the frequency of the VSG other than itself, the input energy of the local VSG is reduced, and thus <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dω_i/dt</i> increases. On the contrary, when the local frequency is less than others, the input energy is increased, and thus <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dω_i/dt</i> decreases. In this way, all frequencies get close to each other in the dynamic process with the method. The idea is verified by the stability analysis. Participation factor analysis and sensitivity analysis are presented to guide parameter design. Finally, the effectiveness of the decentralized mutual damping method is verified through the simulation results and experimental results.

A Novel Damping Control of Grid-Connected Converter Based on Optimal Split-Inductor Concept.

In this paper, a grid-connected converter is investigated. Since the AC side of the grid-connected converter is the LC filter, there is a second-order system resonance problem, and the conventional passive damping control has an inherent limitation of excessive power loss. Based on the mathematical model, a new damping control method is proposed in this paper. It is compared with the traditional solution in terms of damping effect, power loss and system stability. The optimal inductor split ratio is also discussed. The theoretical analysis demonstrates that the proposed method can not only achieve almost the same damping effect as the conventional solution, but also reduce the power loss of the damping resistor. The experimental tests are carried out and the experimental results verify the effectiveness of the proposed method.

Phase Feedforward Damping Control Method for Virtual Synchronous Generators

Damping control plays an important role in suppressing the oscillation modes of virtual synchronous generators (VSGs). The most widely used damping control method through a frequency deviation feedback path is confronted with multiple challenging inherent contradictions among the different control objectives, resulting in seriously degraded control performance of VSGs. To resolve these contradictions fundamentally, this article proposes a novel phase feedforward damping (PFD) control method for VSG from the perspective of restructuring the damping controller. It replaces the traditional frequency deviation feedback path with a novel damping controller utilizing a phase feedforward path. Then, considering the grid-connected and islanding operation modes, respectively, a detailed comparative study of the traditional damping-based VSG (Tra-VSG) and the PFD-based VSG (PFD-VSG) is conducted. Both the theoretical and experimental results demonstrate convincingly that the proposed PFD control method can reconcile the different control objects of VSG, and thus, compared with Tra-VSG, PFD-VSG exhibits vastly superior response performance of the active power and the frequency in both grid-connected and islanding operation modes.