615 research outputs found

    Observer-based tuning of two-inertia servo-drive systems with integrated SAW torque transducers

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    This paper proposes controller design and tuning methodologies that facilitate the rejection of periodic load-side disturbances applied to a torsional mechanical system while simultaneously compensating for the observer’s inherent phase delay. This facilitates the use of lower-bandwidth practically realizable disturbance observers. The merits of implementing full- and reduced-order observers are investigated, with the latter being implemented with a new low-cost servo-machine-integrated highband width torque-sensing device based on surface acoustic wave (SAW) technology. Specifically, the authors’ previous work based on proportional–integral–derivative (PID) and resonance ratio control (RRC) controllers (IEEE Trans. Ind. Electron., vol. 53, no. 4, pp. 1226–1237, Aug. 2006) is augmented with observer disturbance feedback. It is shown that higher-bandwidth disturbance observers are required to maximize disturbance attenuation over the low-frequency band (as well as the desired rejection frequency), thereby attenuating a wide range of possible frequencies. In such cases, therefore, it is shown that the RRC controller is the preferred solution since it can employ significantly higher observer bandwidth, when compared to PID counterparts, by virtue of reduced noise sensitivity. Furthermore, it is demonstrated that the prototype servo-machine-integrated 20-N · mSAWtorque transducer is not unduly affected by machine-generated electromagnetic noise and exhibits similar dynamic behavior as a conventional instrument inline torque transducer

    Improved performance of motor-drive systems by SAW shaft torque feedback

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    The paper describes the application of a non-contact, high bandwidth, low cost, SAW-based torque measuring system for improving the dynamic performance of industrial process motor-drive systems. Background to the SAW technology and its motor integration is discussed and a resonance ratio control (RRC) technique for the coordinated motion control of multi-inertia mechanical systems, based on the measurement of shaft torque via a SAW-based torque sensor is proposed. Furthermore, a new controller structure, RRC plus disturbance feedback is proposed, which enables the controller to be designed to independently satisfy tracking and regulation performance. A tuning method for the RRC structure is given based on the ITAE index, normalized as a function of the mechanical parameters enabling a direct performance comparison between a basic proportional and integral (PI) controller. The use of a reduced-order state observer is presented to provide a dynamic estimate of the load-side disturbance torque for a multi-inertia mechanical system, with an appraisal of the composite closed-loop dynamics. The control structures are experimentally validated and demonstrate significant improvement in dynamic tracking performance, whilst additionally rejecting periodic load side disturbances, a feature previously unrealisable except by other, high-gain control schemes that impose small stability margins

    SAW torque transducers for disturbance rejection and tracking control of multi-inertia servo-drive systems

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    The paper proposes a resonance ratio control (RRC) technique for the coordinated motion control of multi-inertia mechanical systems, based on the measurement of shaft torque via a SAW-based torque sensor. Furthermore, a new controller structure, RRC plus disturbance feedback is proposed, which enables the controller to be designed to independently satisfy tracking and regulation performance. A tuning method for the RRC structure is given based on the ITAE index, normalized as a function of the mechanical parameters enabling a direct performance comparison between a basic proportional and integral (PI) controller. The use of a reduced-order state observer is presented to provide a dynamic estimate of the load-side disturbance torque for a multi-inertia mechanical system, with an appraisal of the composite closed-loop dynamics. It is shown that the integrated formulation of the tuning criteria enables lower bandwidth observers to be implemented with a corresponding reduction in noise and computational load. The control structures are experimentally validated via a purpose designed test facility and demonstrate significant improvement in dynamic tracking performance, whilst additionally rejecting periodic load side disturbances, a feature previously unrealisable except by other, high-gain control schemes that impose small stability margins

    Observer based tuning techniques and integrated SAW torque transducers for two-inertia servo-drive systems

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    A controller design and tuning methodology is proposed that facilitates the rejection of periodic load-side disturbances applied to a torsional mechanical system, whilst simultaneously compensating for the disturbance observer's inherent phase delay, thereby facilitating the used of lower bandwidth, practically realisable, disturbance observers. The merits of implementing both a full- and reduced order observer, is investigated, with the latter being implemented with a new low-cost, high-bandwidth torque sensing device based on surface acoustic wave technolog

    High-performance control of dual-inertia servo-drive systems using low-cost integrated SAW torque transducers

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    Abstract—This paper provides a systematic comparative study of compensation schemes for the coordinated motion control of two-inertia mechanical systems. Specifically, classical proportional–integral (PI), proportional–integral–derivative (PID), and resonance ratio control (RRC) are considered, with an enhanced structure based on RRC, termed RRC+, being proposed. Motor-side and load-side dynamics for each control structure are identified, with the “integral of time multiplied by absolute error” performance index being employed as a benchmark metric. PID and RRC control schemes are shown to be identical from a closed-loop perspective, albeit employing different feedback sensing mechanisms. A qualitative study of the practical effects of employing each methodology shows that RRC-type structures provide preferred solutions if low-cost high-performance torque transducers can be employed, for instance, those based on surface acoustic wave tecnologies. Moreover, the extra degree of freedom afforded by both PID and RRC, as compared with the basic PI, is shown to be sufficient to simultaneously induce optimal closed-loop performance and independent selection of virtual inertia ratio. Furthermore, the proposed RRC+ scheme is subsequently shown to additionally facilitate independent assignment of closed-loop bandwidth. Summary attributes of the investigation are validated by both simulation studies and by realization of the methodologies for control of a custom-designed two-inertia system

    An Active Disturbance Rejection Based Approach to Vibration Suppression in Two‐Inertia Systems

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    This study concerns the resonance problems found in motion control, typically described in a two‐inertia system model as compliance between the motor and the load. We reformulate the problem in the framework of active disturbance rejection control (ADRC), where the resonance is assumed to be unknown and treated as disturbance, estimated and mitigated. This allows the closed‐loop bandwidth to go well beyond the resonant frequency, which is quite difficult using existing methods. In addition, such level of performance is achieved with minimum complexity in the controller design and tuning: no parameter estimation or adaptive algorithm is needed, and the controller is tuned by adjusting one parameter, namely, the bandwidth of the control loop. It is also shown that the proposed solution applies to both the velocity and position control problems, and the fact that ADRC offers an effective and practical motion control solution, in the presence of unknown resonant frequency within the bandwidth of the control system. Finally, frequency response analysis is performed where stability margin is obtained before the simulation results are verified in the hardware experiments

    Kompenzacija sustava s rezonancijom i vremenskim kašnjenjem pomoću valnog kompenzatora

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    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

    Vibration Suppression Controller of Multi-Mass Resonance System Using Fuzzy Controller

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    Vibration suppression control of the mechanical system is a very important technology for realizing high precision, high speed response and energy saving. In general, the mechanical system is modeled with a multi-mass resonance system, and vibration suppression control is applied. This chapter presents a novel controller design method for the speed control system to suppress the resonance vibration of two-mass resonance system and three-mass resonance system. The target systems are constructed by a motor, finite rigid shafts, and loads. The control system consists of a speed fuzzy controller and a proportional-integral (PI) current controller to realize precise speed and torque response. In order to implement the experimental system, the system is treated as the digital control. This chapter also utilizes a differential evolution (DE) to determine five optimal controller parameters (three scaling factors of the fuzzy controller and two controller gains of PI current controller. Finally, this chapter verified the effectiveness to suppress the resonance vibrations and the robustness of the proposed method by the computer simulations and the experiments by using the test experimental setup

    Practical Solutions to the Non-Minimum Phase and Vibration Problems Under the Disturbance Rejection Paradigm

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    This dissertation tackles two kinds of control problems under the disturbance rejection paradigm (DRP): 1) the general problem of non-minimum phase (NMP) systems, such as systems with right half plane (RHP) zeros and those with time delay 2) the specific problem of vibration, a prevailing problem facing practicing engineers in the real world of industrial control. It is shown that the DRP brings to the table a refreshingly novel way of thinking in tackling the persistently challenging problems in control. In particular, the problem of NMP has confounded researchers for decades in trying to find a satisfactory solution that is both rigorous and practical. The active disturbance rejection control (ADRC), originated from DRP, provides a potential solution. Even more intriguingly, the DRP provides a new framework to tackle the ubiquitous problem of vibration, whether it is found in the resonant modes in industrial motion control with compliant load, which is almost always the case, or in the microphonics of superconducting radio frequency (SRF) cavities in high energy particle accelerators. That is, whether the vibration is caused by the environment or by the characteristics of process dynamics, DRP provides a single framework under which the problem is better understood and resolved. New solutions are tested and validated in both simulations and experiments, demonstrating the superiority of the new design over the previous ones. For systems with time delay, the stability characteristic of the proposed solution is analyze
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