Automatic Balancing Research Articles

System Analysis of Automatic Balancing (Self-Balancing) Machine Rotors with Liquid Working Bodies

This article deals with automatic balancing (self-equalizing) of rotors with vertical axis of rotation by means of liquid. There used to be a statement claiming that automatic balancing was possible only after first critical (above resonance) rotation zone of rotors. However in 1995 the phenomenon of automatic balancing with liquid in both below resonance zone of rotor rotation and in the resonance itself was registered using the method of high speed video shooting. The paper suggests theoretical explanation of the phenomenon stated by means of carried out experiments.

Hierarchical Bayesian Calibration and On-line Updating Method for Influence Coefficient of Automatic Dynamic Balancing Machine

Measurement error of unbalance’s vibration response plays a crucial role in calibration and on-line updating of influence coefficient(IC). Focusing on the two problems that the moment estimator of data used in calibration process cannot fulfill the accuracy requirement under small sample and the disturbance of measurement error cannot be effectively suppressed in updating process, an IC calibration and on-line updating method based on hierarchical Bayesian method for automatic dynamic balancing machine was proposed. During calibration process, for the repeatedly-measured data obtained from experiments with different trial weights, according to the fact that measurement error of each sensor had the same statistical characteristics, the joint posterior distribution model for the true values of the vibration response under all trial weights and measurement error was established. During the updating process, information obtained from calibration was regarded as prior information, which was utilized to update the posterior distribution of IC combined with the real-time reference information to implement online updating. Moreover, Gibbs sampling method of Markov Chain Monte Carlo(MCMC) was adopted to obtain the maximum posterior estimation of parameters to be estimated. On the independent developed dynamic balancing testbed, prediction was carried out for multiple groups of data through the proposed method and the traditional method respectively, the result indicated that estimator of influence coefficient obtained through the proposed method had higher accuracy; the proposed updating method more effectively guaranteed the measurement accuracy during the whole producing process, and meantime more reasonably compromised between the sensitivity of IC change and suppression of randomness of vibration response.

C34 フラフープを用いた制振装置の研究(OS13 機械における非線形振動1)

This paper deals with the problem of vibration quenching of the system with a limited power supply using a Hula-Hoop. Following was made clear from the results of numerical analysis and experiment: (1) It is confirmed that the self-excited vibration such as the one observed in automatic balancer is not capable of generating. (2) This device is very effective in the region exceeding the resonant point of the system. (3) Both vibration quenching and energy saving are able to be established by using the bearing with small rotating resistance for Hula-Hoop. (4) The experimental and the analytical results were in good qualitative agreement with each other.

536 自動ボールバランサの性能向上

536 自動ボールバランサの性能向上

Stability Analysis of a Three-Ball Automatic Balancer

Ball-type automatic balancers can effectively reduce the vibrations of optical disk drives due to the inherent imbalance of the disk. Although the ball-type automatic balancer used in practice consists of several balls moving along a circular orbit, few studies have investigated the dynamic characteristics of ball-type balancers with more than two balls. The aim of this paper is to study the dynamic characteristics of a three-ball automatic balancer. Emphasis is put on the effects of the number of balls on the stability of the perfect balancing positions—the equilibrium positions where the disk is perfectly balanced. A theoretical model of an optical disk drive packed with a three-ball automatic balancer is constructed first. The governing equations of the theoretical model are derived using Lagrange’s equations. Closed-form formulas for the equilibrium positions are presented. The stability of the perfect balancing positions is checked with the variations for a pair of design parameters. Stable regions of the perfect balancing positions in the parameter plane of a three-ball balancer are identified and compared with those of a two-ball balancer.

Analytical study of the stability of a two-ball automatic balancer

A ball-type automatic balancer, which consists of several balls moving on a circular orbit, can effectively reduce the imbalance vibrations of an optical-disk drive. Under proper working conditions, the balls can counter-balance the imbalance of a disk by positioning the appropriate angles relative to the mass center of the disk. These particular positions are referred to as the perfect balancing positions. The proper working conditions depend on the stability of the perfect balancing positions. Much work has been done to determine the stability of the equilibrium positions numerically for some specific values of the system parameters. This paper, in contrast, analytically studies the stability characteristics of the equilibrium positions under several conditions. A theoretical model of an optical-disk drive packed with a two-ball automatic balancer is constructed first. The governing equations of the theoretical model are derived using Lagrange's equations. The closed-form formulae and the existence conditions for the equilibrium positions are presented. Experiments are conducted to verify the theoretical model. The stability of each equilibrium position is determined by Routh's criterion. Finally, general guidelines on the stability of the equilibrium positions are proposed.

Automatic data distribution and load balancing with space-filling curves: implementationin CONQUEST

We present an automatic, spatially local data distribution and load balancing schemeapplicable to many-body problems running on parallel architectures. The particledistribution is based on spatial decomposition of the simulation cell. A one-dimensionalHilbert curve is mapped onto the three-dimensional real space cell, which reduces thedimensionality of the problem and provides a way to assign different spatially local parts ofthe cell to each processor. The scheme is independent of the number of processors. Itcan be used for both ordered and disordered structures and does not dependon the dimensionality or shape of the system. Details of implementation in thelinear-scaling density functional code CONQUEST, as well as several case studiesof systems of various complexity, containing up to 55 755 particles, are given.

Software-Controlled Priority Characterization of POWER5 Processor

Due to the limitations of instruction-level parallelism, thread-level parallelism has become a popular way to improve processor performance. One example is the IBM POWER5TM processor, a two-context simultaneous-multithreaded dual-core chip. In each SMT core, the IBM POWER5 features two levels of thread resource balancing and prioritization. The first level provides automatic in-hardware resource balancing, while the second level is a software-controlled priority mechanism that presents eight levels of thread priorities. Currently, software-controlled prioritization is only used in limited number of cases in the software platforms due to lack of performance characterization of the effects of this mechanism. In this work, we characterize the effects of the software-based prioritization on several different workloads. We show that the impact of the prioritization significantly depends on the workloads coscheduled on a core. By prioritizing the right task, it is possible to obtain more than two times of throughput improvement for synthetic workloads compared to the baseline. We also present two application case studies targeting two different performance metrics: the first case study improves overall throughput by 23.7% and the second case study reduces the total execution time by 9.3%. In addition, we show the circumstances when a background thread can be run transparently without affecting the performance of the foreground thread.

Three-Port Triple-Half-Bridge Bidirectional Converter With Zero-Voltage Switching

A three-port triple-half-bridge bidirectional dc-dc converter topology is proposed in this paper. The topology comprises a high-frequency three-winding transformer and three half-bridges, one of which is a boost half-bridge interfacing a power port with a wide operating voltage. The three half-bridges are coupled by the transformer, thereby providing galvanic isolation for all the power ports. The converter is controlled by phase shift, which achieves the primary power flow control, in combination with pulsewidth modulation (PWM). Because of the particular structure of the boost half-bridge, voltage variations at the port can be compensated for by operating the boost half-bridge, together with the other two half-bridges, at an appropriate duty cycle to keep a constant voltage across the half-bridge. The resulting waveforms applied to the transformer windings are asymmetrical due to the automatic volt-seconds balancing of the half-bridges. With the PWM control it is possible to reduce the rms loss and to extend the zero-voltage switching operating range to the entire phase shift region. A fuel cell and supercapacitor generation system is presented as an embodiment of the proposed multiport topology. The theoretical considerations are verified by simulation and with experimental results from a 1 kW prototype.

Automatic two-plane balancing for rigid rotors

We present an analysis of a two-plane automatic balancing device for rigid rotors. Ball bearings, which are free to travel around a race, are used to eliminate imbalance due to shaft eccentricity or misalignment. The rotating frame is used to derive autonomous equations of motion and the symmetry breaking bifurcations of this system are investigated. Stability diagrams in various parameter planes show the coexistence of a stable balanced state with other less desirable dynamics.

Ball detection apparatus for detecting when a golf ball is hit off a golf tee

The ball detection apparatus is for detecting when a golf ball is hit off a golf tee of an automatic golf ball teeing machine. The detection apparatus comprises a radar device for producing a first signal in response to detecting movement of a golf club towards the tee, a directional microphone for producing a second signal in response to detecting the sound of a golf club striking a golf ball and monitoring means for detecting a coincidence between the first and second signals. An automatic golf ball teeing machine including such ball detection apparatus is also disclosed.

GPU Color Constancy

A sensor located inside a digital camera is only able to measure the light that is reflected by an object. The reflected light varies with the spectral power distribution of the illuminant. Hence, images taken with a digital camera may show a strong color cast if an incorrect white balance setting has been chosen. Such a color cast may also be due to an automatic white balance not working correctly. In contrast, colors perceived by a human observer appear to be approximately constant. Algorithms for automatic white balance try to mimic this ability and compute a color-corrected image that appears to have been taken under an illuminant with a uniform power distribution. I show how color-constancy algorithms can be implemented very efficiently on modern graphics processing units.

648 隔壁をもつ自動ボールバランサ

Vibration characteristics of a rotor with a ball balancer are investigated. It is shown that , when balls more than 3 are installed, infinite number of solution for the ball positions are obtained although the automatic balancing is attained. When the rotor is accelerated, the balls rotate in the rotor with satisfying the balancing condition. The almost periodic motion which is the major defect of the ball balancer can be decreased by making partitions in the rotor. When more than 3 partitions are used, the rotor is balanced for any position of the unbalance. When 2 partitions are used, the rotor is not balanced for some range of unbalance.

647 自動ボールバランサによる非線形共振の制振

647 自動ボールバランサによる非線形共振の制振

A Trajectory-Based Ball Tracking Framework with Visual Enrichment for Broadcast Baseball Videos *

Pitching contents play the key role in the resultant victory or defeat in a baseball game. Utilizing the physical characteristic of ball motion, this paper presents a trajectory-based framework for automatic ball tracking and pitching evaluation in broadcast baseball videos. The task of ball detection and tracking in broadcast baseball videos is very challenging because in video frames, the noises may cause many ball-like objects, the ball size is small, and the ball may deform due to its high speed movement. To overcome these challenges, we first define a set of filters to prune most non-ball objects but retain the ball, even if it is deformed. In ball position prediction and trajectory extraction, we analyze the 2D distribution of ball candidates and exploit the characteristic that the ball trajectory presents in a near parabolic curve in video frames. Most of the non-qualified trajectories are pruned, which greatly improves the computational efficiency. The missed balls can also be recovered in the trajectory by applying the position prediction. The experiments of ball tracking on the testing sequences of JPB, MLB and CPBL captured from different TV channels show promising results. The ball tracking framework is able to extract the ball trajectory, superimposed on the video, and in near real-time provide visual enrichment before the next pitch coming up without specific cameras or equipments set up in the stadiums. It can also be utilized in strategy analysis and intelligence statistics for player training.

A Novel Low‐Torque Ball Re‐Positioning Scheme Based on a Sliding‐Mode Ball Observer for an Automatic Balancer System

A novel low‐torque ball re‐positioning scheme based on a sliding‐mode ball observer is developed in this study with the aim to precisely reside the rolling ball inside an automatic balancer system (ABS) to its desired position – 180 degree opposite to the inherent imbalance of the rotating system which the ABS is attached to. In this way, the ABS is capable of substantially reducing radial vibrations of the rotating system for a decent balancing. For preliminary feasibility, the case of a single ball is considered in this study. The first step is to establish the dynamic model of the system, which is followed by the analysis to ensure stability of the desired ball position. The second step is to forge a sliding‐mode observer for estimating on‐line position and velocity of the ball. With ball estimation capability, a low‐torque speed regulator that essentially generates a series of speed drops to the neighborhood of suspension resonance is proposed to overcome practical ball rolling friction for residing the ball at the desired position. The design characteristic of low‐torque required for the regulator is particularly suited to most of commercial spindle motors which can only output limited torques at high speeds. Finally, simulations and experiments are conducted for a benchmark problem of optical disc drives in order to verify the effectiveness of the proposed scheme of the sliding‐mode observer and the low‐torque speed regulator.

FEATURE SELECTION BASED ON MINIMUM ERROR MINIMAX PROBABILITY MACHINE

Feature selection is an important task in pattern recognition. Support Vector Machine (SVM) and Minimax Probability Machine (MPM) have been successfully used as the classification framework for feature selection. However, these paradigms cannot automatically control the balance between prediction accuracy and the number of selected features. In addition, the selected feature subsets are also not stable in different data partitions. Minimum Error Minimax Probability Machine (MEMPM) has been proposed for classification recently. In this paper, we outline MEMPM to select the optimal feature subset with good stability and automatic balance between prediction accuracy and the size of feature subset. The experiments against feature selection with SVM and MPM show the advantages of the proposed MEMPM formulation in stability and automatic balance between the feature subset size and the prediction accuracy.

Conditions for balancing a rotating body in an isolated system with automatic balancers

Conditions are established for automatic balancers with rigid bodies to balance a rotating body that undergoes spatial motion and is a component of an isolated system. It is discovered that a rotating oblate body can be statically balanced when the balance plane is rather close to the center of mass of the system. It is also established that if the rotating body is prolate, the nutation angle can be initially decreased by balancing the body; however, it will then increase because of the dissipation of energy in the system

Integrating Color Constancy Into JPEG2000

The human visual system is able to perceive colors as approximately constant. This ability is known as color constancy. In contrast, the colors measured by a sensor vary with the type of illuminant used. Color constancy is very important for digital photography and automatic color-based object recognition. In digital photography, this ability is known under the name automatic white balance. A number of algorithms have been developed for color constancy. We review two well-known color constancy algorithms, the gray world assumption and the Retinex algorithm and show how a color constancy algorithm may be integrated into the JPEG2000 framework. Since computer images are usually stored in compressed form anyway, little overhead is required to add color constancy into the processing pipeline.

Investigation of a multi-ball, automatic dynamic balancing mechanism for eccentric rotors

This paper concerns an analytical and experimental investigation into the dynamics of an automatic dynamic balancer (ADB) designed to quench vibration in eccentric rotors. This fundamentally nonlinear device incorporates several balancing masses that are free to rotate in a circumferentially mounted ball race. An earlier study into the steady state and transient response of the device with two balls is extended to the case of an arbitrary number of balls. Using bifurcation analysis allied to numerical simulation of a fully nonlinear model, the question is addressed of whether increasing the number of balls is advantageous. It is found that it is never possible to perfectly balance the device at rotation speeds comparable with or below the first natural, bending frequency of the rotor. When considering practical implementation of the device, a modification is suggested where individual balls are contained in separate arcs of the ball race, with rigid partitions separating each arc. Simulation results for a partitioned ADB are compared with those from an experimental rig. Close qualitative and quantitative match is found between the theory and the experiment, confirming that for sub-resonant rotation speeds, the ADB at best makes no difference to the imbalance, and can make things substantially worse. Further related configurations worthy of experimental and numerical investigation are proposed.