Vibration Compensation Research Articles

Research on vibration compensation mechanism of engine ellipse timing system and belt tension distribution at meshing points

Research on vibration compensation mechanism of engine ellipse timing system and belt tension distribution at meshing points

Research on vibration compensation control of electromagnetic bearings rotor

Research on vibration compensation control of electromagnetic bearings rotor

Vibration compensation using dummy load-cell in dynamic mass measurement

Checkweighers, that can measure the mass of a target object continuously while conveying the object on a belt conveyor, are affected by environmental vibration. As a result, accuracy of the mass measurement gets worse. To solve this problem, we have proposed a method that can eliminate the effect of the environmental vibration. This paper enhances the proposed method and improves the performance of the proposed method.

Longitudinal vibration compensation model of stepped-pipe strings in deep-sea mining.

In this paper, the dynamic model of the rigid space stepped-pipe strings system is derived with Lagrangian method to represent the system dynamic behaviors which enriches the analysis method of longitudinal vibration of stepped-pipe strings. The stepped-pipe strings is constructed of pipes with different diameters and lengths, the physical properties of which mainly depends on the axial force and the depth of deep-sea mining. Based on lumped element method, the heave compensation system with dynamic vibration absorber is designed for longitudinal vibration suppression of the stepped-pipe strings. The analytical solution is obtained by modal analysis method when the mining ship is subjected to sea breeze excitation. The proposed method is easily implementable for rigid space stepped-pipe strings system with complex multi-degree-of-free deep-sea mining dynamic model. Furthermore, the optimal combination of mass ratio, spring coefficient and damping ratio is shown to have a better vibration suppression performance. Finally, numerical simulations on the stepped-pipe strings system with or without dynamic vibration absorbers are provided to demonstrate the effectiveness of the proposed method.

Control scheme of adaptive feedforward cancellation considering of Bode’s integral theorem for synchronous vibration suppression in rotating machineries

Synchronous vibration is a major obstacle to the stable operation of rotating machineries. In previous studies, active control methods were developed to compensate for synchronous vibration using actuators, such as an active magnetic bearing or a piezo actuator. Adaptive feedforward cancellation is another well-known control method and is used to compensate for the synchronous vibration in the actual system. The control methods can compensate for the synchronous vibration; however, the amplitude of the vibration in other frequency ranges can be increased by the waterbed effect due to Bode’s integral theorem. Therefore, there is a trade-off between the compensation of the synchronous vibration and the negative impact of other vibration. In this article, a novel control scheme for the adaptive feedforward cancellation is proposed to eliminate the negative impact due to the waterbed effect. The proposed method controlled the input signal of the adaptive algorithm in the adaptive feedforward cancellation and realized an ideal feedforward controller worked independently from the feedback loop. The effectiveness of this method was verified experimentally using a test rig.

Adaptive feedforward vibration compensation control strategy of bearingless induction motor

In order to solve the unbalanced vibration problem of bearingless induction motor caused by the rotor mass eccentricity, an adaptive feedforward vibration compensation control strategy is researched. Firstly, the inverse dynamic decoupling control me

A Novel High-Frequency Vibration Error Estimation and Compensation Algorithm for THz-SAR Imaging Based on Local FrFT.

Compared with microwave synthetic aperture radar (SAR), terahertz SAR (THz-SAR) is easier to achieve ultrahigh-resolution image due to its higher frequency and shorter wavelength. However, higher carrier frequency makes THz-SAR image quality very sensitive to high-frequency vibration error of motion platform. Therefore, this paper proposes a novel high-frequency vibration error estimation and compensation algorithm for THz-SAR imaging based on local fractional Fourier transform (LFrFT). Firstly, the high-frequency vibration error of the motion platform is modeled as a simple harmonic motion and THz-SAR echo signal received in each range pixel can be considered as a sinusoidal frequency modulation (SFM) signal. A novel algorithm for the parameter estimation of the SFM signal based on LFrFT is proposed. The instantaneous chirp rate of the SFM signal is estimated by determining the matched order of LFrFT in a sliding small-time window and the vibration acceleration is obtained. Hence, the vibration frequency can be estimated by the spectrum analysis of estimated vibration acceleration. With the estimated vibration acceleration and vibration frequency, the SFM signal is reconstructed. Then, the corresponding THz-SAR imaging algorithm is proposed to estimate and compensate the phase error caused by the high-frequency vibration error of the motion platform and realize high-frequency vibration error estimation and compensation for THz-SAR imaging. Finally, the effectiveness of the novel algorithm proposed in this paper is demonstrated by simulation results.

Vibration Compensation of Checkweigher Using Acceleration Sensor

The checkweigher is a device that measures mass continuously and it carries out mass measurement while conveying an object on a belt conveyor. It is a device that operated an active role in various fields such as food, medicine, and industrial products. Although the load cell scale is often used to measure measurement in the checkweigher, due to the structure of load cell, the accuracy is susceptible to environmental vibration. It is difficult to generate low frequency input such as floor vibration with the general vibration exciter. We first manufactured a device that can reproduce environmental vibration. In this study, we present the response of the load cell to excited by the device, moreover consider the vibration compensation using an acceleration sensor.

Design of an interferometer/polarimeter for DTT

Laser interferometer/polarimeter systems are used in magnetically confined fusion experiments for simultaneous measurements of the line-integrated electron density and of the current-induced magnetic field. In this work, we present the design of the interferometer/polarimeter system for the Divertor Tokamak Test facility (DTT), a new tokamak device dedicated to investigate alternative power exhaust solutions for the nuclear fusion DEMOnstration Power Station (DEMO). The optical design is based on the exploitation of a 7+7 chords scheme, which allows determining density and poloidal field, contributes to evaluate the plasma magnetic equilibrium and can provide the real time estimate of the q profile. Since the optical scheme is thought to be compatible with a possible Double Null divertor configuration, an equatorial port is recommended. In order to protect the in-vessel optics, each chord employs a back reflecting mirror installed in the high field side inner wall close to the divertor, where some plasma-free space is available, and one retroreflector installed in the space behind the low field side outer first wall. With respect to polarimetric measurements and low effects of density gradients, the optimal laser source solution would be 100/50 μm. With this setup, in low/medium density conditions, the longer wavelength will provide a good magnetic field measurement, while the shorter wavelength will allow vibration compensation for density measurements. In high-density regimes, the short wavelength alone can provide both magnetic field information from Faraday rotation and density measurements from the Cotton-Mouton effect. The two wavelengths are close enough to each other also to provide a good sharing of optical components.

Model-based vibration control for optical lenses

This work presents a contribution to the active image stabilization of optical systems, involving model development, control design, and the hardware setup. A laboratory experiment is built, which demonstrates the vibration sensitivity of a mechanical-optical system. In order to stabilize the undesired image motion actively, a model-based compensation of the image vibration is developed, realized and tested. Beside a linear actuator motion system, a force sensor system and a position sensor system are introduced and analyzed. In particular, various low-cost hardware components of the Arduino platform are used, which support the deployment of the controller software based on Matlab-Simulink. The remaining image motion is measured with a high-speed vision sensor system and the performance of the overall system is assessed.

Vibration analysis of moving machine tool axes based on phase information in video data

Vibrations of machine tools limit quality and productivity and therefore need to be analyzed. Video based vibration analysis using spatial phase information could in principle reduce measuring effort significantly. However, feasibility of these approaches for moving machine tool axes and relative movement between camera and object is yet to be shown. This paper investigates an approach for stabilizing linear axis movement to analyze vibration. It is shown that shaker induced vibration on a linearly moving clamping tower can be derived for low frequencies. However, influences of actual cutting processes as well as compensation of unwanted camera vibration needs further investigation.

Performance Improvement of Active MacPherson Suspension Using a Pneumatic Muscle and an Intelligent Vibration Compensator

This paper presents an intelligent control strategy for an active MacPherson suspension driven by a pneumatic muscle (PM) actuated system and evaluates its improved control performance on a self-developed test-rig. To fulfill the fully-functional test and analysis of active suspension systems, this test-rig comprises three units: 1. an active MacPherson suspension unit, which consists of a PM mechanism and two MacPherson struts, is built to isolate vibration from road disturbances; 2. a road profile generator (RPG) unit, which can produce a vertical force to lift the car-body according to various road profiles; 3. a PC-based control (PBC) unit, which computes, sends and receives signals for both of the active MacPherson suspension and the PC-based control unit. The objective of this study is to improve the MacPherson suspension in terms of the capability of road vibration isolation by using the PM actuation that can actively provide extra compensatory force for MacPherson struts. Then, for motion control of the PM, this study employs an interval type-2 adaptive fuzzy controller to approximate the optimal control law and adopts a self-tuning and fuzzy sliding mode compensator to compensate unmodeled dynamics for the active MacPherson suspension system. Three experiments are conducted to compare the active MacPherson suspension system with the original MacPherson struts through various road profiles on the test-rig. The results show the significant improvement for the proposed active MacPherson suspension system in suppressing the displacement and acceleration of the car-body.

Development of Vibration Compensator for Vertical Vibration Damping of Ships

Development of Vibration Compensator for Vertical Vibration Damping of Ships

Rotor Vibration Control of a Bearingless Induction Motor Based on Unbalanced Force Feed-Forward Compensation and Current Compensation

To handle the unbalanced vibration caused by uneven rotor mass distribution in a bearingless induction motor (BIM), a control strategy that integrates unbalanced feed-forward compensation and current compensation is presented. Firstly, based on the analysis of the BIM rotor vibration mechanism and the unbalanced vibration influence on the performance of the BIM, the dynamic model of the rotor is derived. Secondly, an unbalanced force feed-forward compensation controller is designed to extract the synchronous vibration signals through the synchronous signal detection unit, and then the compensation force components are generated by unbalanced feed-forward compensation controller. In addition, considering the influence of current in the rotor induced by suspension winding, a current compensation link is applied to the system to enhance the suspension performance. Finally, a rotor unbalanced vibration compensation control system of the BIM is established. The simulation and experimental results show that the proposed compensation control strategy not only can effectively reduce the rotor radial displacement and suppress the unbalanced vibration, but also can improve the suspension performance.

ABS Conversion of Phase Variable Type PGC Applied to Active Magnetic Bearings

The Peak-of Gain Control (PGC) and Auto-Balancing System (ABS) are applied as unbalanced vibration compensation for active magnetic bearings. The PGC applied when passing through the critical speed of the rotor increases bearing stiffness and positively suppresses vibration amplitude of the rotor. On the other hand, ABS is applied at a rotation speed exceeding the critical speed and the amplitude of the rotor becomes small. It has the function of reducing the bearing stiffness. Since PGC and ABS are applied at different rotational speeds, it is necessary to switch connections. When starting up the turbo molecular pump, precise work is carried out even at the rated rotation speed. Therefore, it is necessary to suppress the casing vibration due to the transient phenomenon. Furthermore, a switching circuit for each of PGC and ABS is required. As a result, the entire circuit becomes complicated.

Research on Key Technologies of Powdery Material Dynamic Buoyancy Weighing System Based on Comparative Compensation Method

Dynamic weighing device is widely used in material processing and manufacturing engineering. In the weighing process, due to the viscosity of special powder material, it will produce vibration and be affected by vibration acceleration when adding weighing hopper. Its weighing reading will fluctuate, thus can not accurately carry out dynamic weighing. On the basis of dynamic buoyancy weighing system, the weight sensor and compensation sensor are added to construct the mass spring damping system. Through the analysis of transfer function, it satisfies the condition of using comparative compensation method and can be realized in the same vibration environment. Real-time tracking and compensation of low-frequency random vibration from outside the system (buoyancy) can be performed. In order to greatly improve the weighing accuracy of low frequency random vibration. The experimental results show that the dynamic measurement accuracy of the dynamic buoyancy weighing system can be less than ±0.5% after the comparison and compensation of the dynamic buoyancy weighing system, which can basically meet the weight measurement of powder material.

High-speed laser interferometric distance sensor with reference mirror oscillating at ultrasonic frequencies

Abstract Optical measurement systems are an important part of the portfolio of 3D topography sensors. By precise, contactless and rapid measurements these sensors constitute an alternative to tactile instruments. In this contribution the principle of a laser interferometric distance sensor is presented, which in combination with lateral scan axes acts as a topography sensor and also as distance sensor for the compensation of vibrations in a coherence scanning Linnik interferometer. An advantage of this distance sensor is its high acquisition rate of height values, which in case of working as a topography sensor enables high scan velocities as it is demonstrated at a chirp standard measured with a scan velocity of 80 mm/s. This is much higher than the scan velocity of tactile instruments, which are typically limited up to 1 mm/s. In addition, the compensation of vibration disturbances demonstrates the capability of the fast distance measurement. In contrast to other existing high-speed point sensors the relevant components are mass products. This keeps the costs of the sensor setup in a limited range. Furthermore, the sensor shows potential of much higher measurement rates than 116 kHz provided by the sensor used here.

Vibration Compensation of the Frequency-Scanning-Interferometry-Based Absolute Ranging System

The frequency-scanning-interferometry-based (FSI-based) absolute ranging technology is a type of ranging technology possessing a high precision and no ranging blind area, so it can be used for non-cooperative targets. However, due to a tiny movement of a target, the Doppler shift and the phase modulation are introduced into the beat signal which results in ranging accuracy decrease. In order to solve this problem, first the model of vibration effect is established, and then the beat signals of two adjacent scanning periods are processed to produce a signal that is immune to vibration. The proposed method is verified by the experiments, and the experimental results show that the effect of vibration compensation is better for the target with a lower vibration velocity and at a lower vibration frequency (lower than 6 Hz). When the target is subjected to a sinusoidal vibration with an amplitude of 10 μm at a frequency of 1 Hz, by using the proposed method the standard deviation is reduced from 775 to 12 μm. Moreover, in the natural environment, by using vibration compensation the standard deviation is reduced from 289 to 11 μm.

Vibration compensation of an atom gravimeter

For most atom interferometers, the vibration isolation unit is applied to reduce vibration noise. In our experiment, instead of isolation, the vibration signals are monitored, and combining with the sensitive function, the compensation phase shift for the atom interferometer is obtained. We focus on the correction over a wide spectrum rather than on “monochromatic” frequencies. The sensitivity of the atom gravimeter can be upgraded by a factor of more than two. Furthermore, we demonstrate that the atom interferometer can still produce a good measurement result without passive vibration isolation in extremely noisy environments by using vibration compensation.

Novel Optimization Approach in Ultrasonic Machining: Unilateral Compensation for Resonant Vibration in Primary Side

Resonant frequency and impedance matching have great significance for the vibration performance and online monitoring of the rotary ultrasonic machining. Network compensation is a typical solution to match the resonant frequency and the impedance between the rotary ultrasonic holder (RUH) and the ultrasonic transducer. However, the traditional bilateral compensation method could adversely affect the rotary dynamic balance of the RUH. Currently, the existing unilateral compensation methods can only realize the resonant frequency matching. A novel unilateral compensation method that satisfies both the resonant frequency and the impedance matching is proposed. First, the impedance model of the RUH vibrating system is established according to its equivalent circuit. It is found that, without any compensation methods, the resonant frequency and the impedance between the RUH and the transducer have deviated. Second, the primary-series and primary-parallel compensation topologies are applied to the RUH system, and the expressions of compensation capacitance value, voltage gain, power transfer efficiency, and output active power are derived. The deviations of the resonant frequency and the impedance are eliminated with primary-series compensation topology; and as a result, the voltage gain is increased from 0.267 to 0.90, the output active power is 11.3 times than that without compensation. Third, the state-space model of primary-series topology is constructed. Finally, the above theoretical results are verified by the experimental results.