Motion Control Systems Sabanovic, Asif; Ohnishi, Kouhei
2011, 2011-01-14, 2011-03-10
eBook
Motion Control Systemsis concerned with design methods that support the never-ending requirements for faster and more accurate control of mechanical motion. The book presents material that is ...fundamental, yet at the same time discusses the solution of complex problems in motion control systems. Methods presented in the book are based on the authors' original research results. Mathematical complexities are kept to a required minimum so that practicing engineers as well as students with a limited background in control may use the book. It is unique in presenting know-how accumulated through work on very diverse problems into a comprehensive unified approach suitable for application in high demanding, high-tech products. Major issues covered include motion control ranging from simple trajectory tracking and force control, to topics related to haptics, bilateral control with and without delay in measurement and control channels, as well as control of nonredundant and redundant multibody systems. Provides a consistent unified theoretical framework for motion control designOffers graduated increase in complexity and reinforcement throughout the bookGives detailed explanation of underlying similarities and specifics in motion controlUnified treatment of single degree-of-freedom and multibody systemsExplains the fundamentals through implementation examplesBased on classroom-tested materials and the authors' original research workWritten by the leading researchers in sliding mode control (SMC) and disturbance observer (DOB)Accompanying lecture notes for instructorsSimulink and MATLAB® codes available for readers to downloadMotion Control Systemsis an ideal textbook for a course on motion control or as a reference for post-graduates and researchers in robotics and mechatronics. Researchers and practicing engineers will also find the techniques helpful in designing mechanical motion systems.
We present a statistical analysis of the first four seasons from a second-generation microlensing survey for extrasolar planets, consisting of near-continuous time coverage of 8 deg to the 2nd power ...of the Galactic bulge by the Optical Gravitational Lens Experiment (OGLE), Microlensing Observations in Astrophysics (MOA), and Wise microlensing surveys. During this period, 224 microlensing events were observed by all three groups. Over 12% of the events showed a deviation from single-lens microlensing, and for approx. 1/3 of those the anomaly is likely caused by a planetary companion. For each of the 224 events, we have performed numerical ray-tracing simulations to calculate the detection efficiency of possible companions as a function of companion-to-host mass ratio and separation. Accounting for the detection efficiency, we find that 55 +34 -22%of microlensed stars host a snowline planet. Moreover, we find that Neptune-mass planets are approx.10 times more common than Jupiter-mass planets. The companion-to-host mass-ratio distribution shows a deficit at q approx. 10 (exp -2), separating the distribution into two companion populations, analogous to the stellar-companion and planet populations, seen in radial-velocity surveys around solar-like stars. Our survey, however, which probes mainly lower mass stars, suggests a minimum in the distribution in the super-Jupiter mass range, and a relatively high occurrence of brown-dwarf companions.
This paper presents a design method of time-delayed control systems. Because of the tremendous spread of computer networks, control strategies for time-delayed control systems are needed for ...network-based control systems (NBCSs) and other network applications. Although model-based or predictive control methods (like a Smith predictor) are often used for time-delay compensation, the performance often deteriorates when the value of time delay is uncertain. In these circumstances, a novel time-delay-compensation method based on the concept of network disturbance (ND) and communication disturbance observer (CDOB) has been proposed. The method has the same effectiveness for time-delay compensation as that of the Smith predictor. Furthermore, because the method works without delay-time model, it can be flexibly applied to many kinds of time-delayed control systems. In this paper, a design method of CDOB, considering the dynamic property of ND, is proposed in the situation of constant time delay. The dynamic property of ND leads to two design conditions of CDOB. Those design conditions are derived considering relationships between poles of CDOB and ND dynamics. Then, the actual design procedure of CDOB based on derived design conditions is presented in two different delay cases. The stability of the designed control systems is clarified by stability analysis. The validity of the proposed design method is verified by experimental results. Finally, we present experimental results in the case of random delay as an example of practical application of the time-delay compensation method to actual NBCSs.
We have examined a dynamical spin injection in a CoFeB/Pt/CoFeB trilayered structure. Although the contribution of the spin pumping was eliminated by the symmetric spin injection from the upper and ...lower CoFeB layers, a clear voltage change due to the inverse spin Hall effect has been observed. We find that the observed signal can be quantitatively explained by considering the thermal spin injection due to the heating effect during ferromagnetic resonance (FMR). This innovative demonstration indicates the significant contribution of FMR heating in the dynamical spin injection.
Aim: To isolate and characterize lactic acid bacteria (LAB) and determine whether they could potentially be used as heavy metal (cadmium and lead) absorbing probiotics. Methods and Results: The study ...used 53 environmental (mud and sludge) samples to isolate cadmium‐ and lead‐resistant LAB, by following spared plate technique. A total of 255 cadmium‐ and lead‐resistant LAB were isolated from these samples. The survival of 26 of the LAB was found after passing through sequential probiotic characterizations. These 26 probiotic LAB exhibited remarkable variations in their metal‐resistant and metal‐removal abilities. Of 26, seven (Cd54‐2, Cd61‐7, Cd69‐12, Cd70‐13, Pb82‐8, Pb96‐19 and Cd109‐16) and four (Pb71‐1, Pb73‐2, Pb85‐9 and Pb96‐19) strains displayed relatively elevated cadmium‐ and lead‐removal efficiencies from water, respectively, compare with that of the remaining strains. Strains Cd70‐13 and Pb71‐1 showed the highest cadmium (25%) and lead (59%) removal capacity from MRS (De Man, Rogosa and Sharpe) culture medium, respectively, amongst the selected strains and showed a good adhesive ability on fish mucus. A phylogenetic analysis of their 16S rDNA sequences revealed that the strains Cd70‐13 and Pb71‐1 belong to Lactobacillus reuteri. Conclusion: Excellent probiotic, metal sorption and adhesive characteristics of newly identified Lact. reuteri strains Cd70‐13 and Pb71‐1 were isolated, which indicated their high potential abilities to survive in the intestinal milieu and to uptake the tested metals from the environment. Significance and Impact of the Study: To our knowledge, this is the first study that has aimed to isolate, characterize and identify metal‐resistant LAB strains that have potential to be a probiotic candidate for food and in vivo challenge studies in the intestinal milieu of fish for the uptake and control of heavy metal bioaccumulation.
Controlling robots in contact with the environment is an important problem in industry applications. In the conventional force control, much research has paid attention to develop novel force control ...systems and implemented force sensors to detect external force. This paper shows that narrow bandwidth of force sensor has a big influence on the force control system. Generally, to solve the instability in force control, the velocity feedback gain is enlarged. The system becomes unstable with small velocity feedback gain, and robot's response becomes slow with large one. Inasmuch as there is a tradeoff between the stability and the response, it is considered that force control by robots is difficult. This paper proposes a force control system with disturbance observer. It is possible to obtain the force information with wide bandwidth by using the disturbance observer. This paper shows that bandwidth of force sensing is very important for contact motion control. By using the wide bandwidth of force sensing, both stability and response are improved. Furthermore, force control is attainable by the construction of the easiest force control architecture. Therefore, the ideal zero-stiffness-force control is attained. The numerical and experimental results show viability of the proposed method.
A mesoscopic multi-terminal superconducting Nb strip with a spin injection terminal has been developed. We investigate the influence of spin polarization on the relaxation process of the ...quasiparticle in the superconducting Nb. The position dependence of the nonlocal voltage provides the quasiparticle relaxation length. The relaxation length for the spin-polarized quasiparticle is found to show a 12.5% increase from that for the un-polarized quasiparticle. This demonstration opens a new avenue for utilization of the spin current in a superconducting device.
In recent years, the realization of a haptic system has been strongly desired in the fields of medical treatment and expert's skill acquisition. The key point of haptics is to realize a vivid ...presentation of reactive force, particularly in applications that involve touching action. In this paper, a realization of the "law of action and reaction" by multilateral control is introduced. First, an analysis and a design of bilateral control based on the disturbance observer are discussed. A disturbance observer is a basic technology for quarrying of disturbance torque and attainment of robust acceleration control. This paper shows that a four-channel controller which is composed of position control and force control in the acceleration dimension is decomposed into two modes: common and differential modes. A design of bilateral control is treated as position and force control in a single joint. The proposed method generates a good realization of reactive force for the slave side at the master side in bilateral force control. Second, bilateral control is extended and multilateral control is generalized. Multilateral control is designed similarly as bilateral control based on the modal decomposition. Robots with a haptic ability will have an important role in human adaptive mechatronics.
Since 1995, more than 500 exoplanets have been detected using different techniques, of which 12 were detected with gravitational microlensing. Most of these are gravitationally bound to their host ...stars. There is some evidence of free-floating planetary-mass objects in young star-forming regions, but these objects are limited to massive objects of 3 to 15 Jupiter masses with large uncertainties in photometric mass estimates and their abundance. Here, we report the discovery of a population of unbound or distant Jupiter-mass objects, which are almost twice (1.8(+1.7)(-0.8)) as common as main-sequence stars, based on two years of gravitational microlensing survey observations towards the Galactic Bulge. These planetary-mass objects have no host stars that can be detected within about ten astronomical units by gravitational microlensing. However, a comparison with constraints from direct imaging suggests that most of these planetary-mass objects are not bound to any host star. An abrupt change in the mass function at about one Jupiter mass favours the idea that their formation process is different from that of stars and brown dwarfs. They may have formed in proto-planetary disks and subsequently scattered into unbound or very distant orbits.
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