Kompenzacija sustava s rezonancijom i vremenskim kašnjenjem pomoću valnog kompenzatora

Recently, teleoperated robots have been researched for working in ultimate environment actively. Developing performance of teleoperated robots, it will be possible for human to work in such a ultimate environment with safety. However, in the actual case, a flexible mechanism caused by the mechanical constraint such as weight saving of robot, using gear, and so on, induces vibration. Moreover, a communication delay causes vibration, too. In addition, in the worst case, the delay makes the control system unstable. Therefore, in this paper, for suppressing the vibration, compensation of integrated resonant and time-delay systems by using a wave compensator is proposed. In the proposal, there are two important control structures. Firstly, a reflected wave in the resonant system is eliminated by a reflected wave rejection. A transfer function of wave equation without the reflected wave is represented as a time delay. Therefore, a resonant system without a reflected wave can be regarded as an equivalent time-delay system. Next, it is defined that an effect of time delay from resonant and communication systems is caused by a time-delay disturbance. Then, vibrations from resonant and communication delays are simultaneously suppressed by the wave compensator. Finally, the validity of the proposal is verified by simulation and experimental results.U posljednje vrijeme daljinski upravljani roboti za rad u izazovnim okruženjima dobivaju na važnosti. Poboljšanje sposobnosti daljinski upravljanih robota neosporno bi omogućilo bi sigurniji rad u takvim okruženjima.Ipak, realne robotske konstrukcije često podrazumijevaju fleksibilne prijenosne mehanizme, zupčanike i druge elemente koji unose nepoželjne vibracije u sustav. Fenomen vibracije dodatno je naglašen i vremenskim kašnjenjem u komunikaciji s robotom što može u konačnici uzrokovati nestabilno ponašanje. U ovom se radu predlaže mehanizam sprječavanja vibracija temeljen na kompenzatoru valova. Mehanizam se sastoji od dvije cjeline. Prvi korak je eliminacija reflektiranog vala. Drugo, prijenosna funkcija valne jednadžbe bez reflektirano vala tretira se kao vremensko kašnjenje. Stoga se rezonantni sustav može promatrati može promatrati kao ekvivalentni sustav s vremenskim kašnjenjem. Nadalje, utjecaj se vremenskog kašnjenja modelira kao poremećaj s vremenskom odgodom. U konačnici se vibracije rezonantnog i komunikacijskog kašnjenja potiskuju kompenzatorom valova. Predloženi je algoritam ispitan u simulacijama kao i na stvarnome sustavu

An Adaptive Periodic-Disturbance Observer for Periodic-Disturbance Suppression

Repetitive operations are widely conducted by automatic machines in industry. Periodic disturbances induced by the repetitive operations must be compensated to achieve precise functioning. In this paper, a periodic-disturbance observer (PDOB) based on the disturbance observer (DOB) structure is proposed. The PDOB compensates a periodic disturbance including the fundamental wave and harmonics by using a time delay element. Furthermore, an adaptive PDOB is proposed for the compensation of frequency-varying periodic disturbances. An adaptive notch filter (ANF) is used in the adaptive PDOB to estimate the fundamental frequency of the periodic disturbance. Simulations compare the proposed methods with a repetitive controller (RC) and the DOB. Practical performances are validated in experiments using a multi-axis manipulator. The proposal provides a new framework based on the DOB structure to design controllers using a time delay element.Comment: 11 pages, 22 figures, journa

1998 Superoutburst of the Large-Amplitude SU UMa-Type Dwarf Nova WX Ceti

We observed the 1998 November superoutburst of WX Cet, a dwarf nova originally proposed as a WZ Sge-like system. The observation established that WX Cet is an SU UMa-type dwarf nova with a mean superhump period of 0.05949(1) d, which is 2.1% longer than the reported orbital period. The lack of early superhumps at the earliest stage of the superoutburst, the rapid development of usual superhumps, and the possible rapid decay of late superhumps seem to support that WX Cet is a fairly normal large-amplitude SU UMa-type dwarf nova, rather than a WZ Sge-type dwarf nova with a number of peculiarities. However, a period increase of superhumps at a rate dot(P)/P = (+8.5+/-1.0) x 10^-5 was observed, which is one of the largest dot(P)/P ever observed in SU UMa-type dwarf novae. A linear decline of light, with a rate of 0.10 mag/d, was observed in the post-superoutburst stage. This may be an exemplification of the decay of the viscosity in the accretion disk after the termination of a superoutburst, mechanism of which is proposed to explain a variety of post-superoutburst phenomena in some SU UMa-type dwarf novae.Comment: 8 pages, 8 figures, accepted for publication in Publ. Astron. Soc. Japa

Bilateralno upravljanje gibanjem za apstrakciju i reprodukciju stvarne sile

In recent years, skill preservation of an expert and skill education for young technical workers have been serious issues in medical and production fields. The best way which young technical workers learn the ripe skill is that an expert teaches them. However, unfortunately, experts have lessened in these years. So, if digital skill preservation like a haptic database is attained, it may become an innovative solution of the above problem. Thus, as the fundamental technology for development of the haptic database, this paper proposes abstraction and reproduction methods on bilateral control of real world force sensation, and reconstruction of real world environment as well. In the abstraction mode, a master-slave system is composed, and the action-reaction law is attained through bilateral control. Later, based on acceleration information, the force, position and velocity of both master and slave systems are estimated and obtained. In the reconstruction mode, an environmental model is reconstructed based on the obtained data from real-world. Next, by using reproduction mode on master side, the operator would feel the force sensation from the obtained environmental model. Here, the proposed system is able to store the bilateral real-world force sensation to a sensation database. Finally, the experimental results show the validity of the proposed method.Održavanje sposobnosti iskusnih operatera i uvježbavanje novih operatera postaje sve važnijim zadatkom u medicinskim i proizvodnim primjenama. Nove operatere najbolje uvježbavaju iskusni operateri, ali njih sve više nedostaje. Inovativno rješenje toga problema može biti pohranjivanje vještina iskusnih operatera u tzv. haptičku bazu podataka. U ovome se članku za razvoj haptičke baze podataka predlažu metode apstrakcije i reprodukcije stvarne sile u bilateralnom upravljanju te metoda rekonstrukcije udaljenoga stvarnoga prostora u kojemu djeluje prateći sustav. U apstrakcijskom načinu rada uspostavlja se bilateralno upravljanje između vodećeg i pratećeg sustava uz održavanje zakona akcije i reakcije između njih. Nakon toga estimiraju se sila, brzina i pozicija vodećeg i pratećeg sustava na temelju informacije o ubrzanju. U rekonstrukcijskom načinu rada rekonstruira se model udaljenoga stvarnoga prostora na osnovi podataka iz stvarnoga udaljenoga prostora. Na koncu, primjenom reprodukcijskog načina rada na strani vodećeg sustava operater bi trebao osjećati silu iz modela udaljenog prostora izgrađenog u rekonstrukcijskom načinu rada. Predloženi sustav omogućuje spremanje bilateralno prenošene sile u bazu podataka, što je potkrijepljeno eksperimentalnim rezultatima

Sinteza bezsenzornog upravljanja silom za fleksibilnog robota korištenjem upravljanja omjerom rezonancija temeljenim na metodi koeficijentnog dijagrama

Generally, the flexible robot system can be modeled as the two-mass system which consists of a motor and load connected by a spring. Thus, its elasticity causes resonance in the system. By using the conventional PID controller, this method cannot perform well in this situation. Much research has proceeded with the aim of reducing vibration. A new effective control method, the resonance ratio control, has been introduced as a new way to guarantee the robustness and suppress the oscillation during task executions for a position and force control. In this paper, three techniques are proposed for improving the performance of resonance ratio control. Firstly, a new multi encoder based disturbance observer (MEDOB) is shown to estimate the disturbance force on the load side. The proposed observer is not necessary to identify the nominal spring coefficient. Secondly, coefficient diagram method (CDM) has been applied to calculate a new gain of the force controller. A new resonance ratio gain has been presented as 2.0. Finally, the MEDOB and load side disturbance observer (LDOB) are employed to identify a spring coefficient of flexible robot system. By using the proposed identification method, it is simple to identify the spring coefficient and easy to implement in the real flexible robot system. The effectiveness of the proposed identification method is verified by simulation and experimental results.Općenito, sustav fleksibilnog robota može se modelirati kao dvomaseni sustav koji se sastoji od motora i tereta povezanih oprugom. Rezonancija sustava posljedica je elastičnosti opruge. Korištenje konvencionalnog PID regulatora ne daje zadovoljavajuće performanse u ovoj situaciji. Provedena su mnoga istraživanja s ciljem smanjenja vibracija. Tako je uvedena nova učinkovita metoda upravljanja, upravljanje omjerom rezonancija, kao novi način da se osigura robusnost i priguše oscilacije tijekom izvršavanja zadatka putem upravljanja pozicijom i silom. U ovom radu predložene su tri tehnike za poboljšanje performansi upravljanja omjerom rezonancija. Prvo, pokazano je kako novi observer poremećaja temeljen na više enkodera (MEDOB) estimira poremećajnu silu na strani tereta. Predloženi observer nije nužan za identifikaciju nominalnog koeficijenta opruge. Drugo, metoda koeficijentnog dijagrama (CDM) je primijenjena za proračun novog pojačanja regulatora sile. Iznos 2.0 je odre.en kao novo pojačanje omjera rezonancija. Konačno, MEDOB i observer poremećaja na strani tereta (LDOB) korišteni su za identifikaciju koeficijenta opruge sustava fleksibilnog robota. Predložena metoda identifikacije jednostavna je za implementaciju na stvarni sustav, te se pomoću nje jednostavno identificira koeficijent opruge. Učinkovitost predložene metode identifikacije provjerena je simulacijski i eksperimentalno

Multilateral control-based motion copying system for haptic training

This paper proposes a new motion-loading method that utilizes a multilateral control-based scheme for the motion-copying system. The motion-copying system refers to human operator's motion, tracks and preserves it only for being able to reproduce the same result of the motion. Conventionally, only slave system was used for motion-loading phase. The method proposed in this paper offers a way to enable more than one slave side actuator at the phase. With the proposed system, the operator at loading phase can grab the master system which the manipulator was holding at the saving phase. The performance analyses of proposed system are made with the bode plots, and the experiments are held with two degrees-of-freedom actuators. The newly proposed haptic informational reproduction technique can be applied in many areas, especially as the training purposes

Application of fuzzy type II multi-layer Kalman filter for parameters identification of two-mass drive system

The paper describes a novel online identification algorithm for a two-mass drive system. The multi-layer extended Kalman Filter (MKF) is proposed in the paper. The proposed estimator has two layers. In the first one, three single extended Kalman filters (EKF) are placed. In the second layer, based on the incoming signals from the first layer, the final states and parameters of the two-mass system are calculated. In the considered drive system, the stiffness coefficient of the elastic shaft and the time constant of the load machine is estimated. To improve the quality of estimated states, an additional system based on II types of fuzzy sets is proposed. The application of fuzzy MKF allows for a shorter identification time, as well as improves the accuracy of estimated parameters. The identified parameters of the two-mass system are used to calculate the coefficients of the implemented control structure. Theoretical considerations are supported by simulations and experimental tests

Industrial applications of the Kalman filter:a review

International audienc