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1

Bilateral teleoperation system for a mini crane

Herbin Paweł, Woźniak Marcin

Zeszyty Naukowe Akademii Morskiej w Szczecinie

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2019

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nr 57 (129)

63--69

EN

In this paper, two automatic mini-crane control systems have been compared; utilizing feedback as well as both feedback and feedforward structures. The proposed control systems were implemented in a Master-Slave system to provide intuitive control for a mini-crane by human muscles. The control systems that have been designed were tested on constructions with similar structures i.e. an upper limb exoskeleton and a mini-crane with two joints, but using different actuation systems. The mini-crane had hydraulic actuators, whereas the exoskeleton was equipped with electrical actuators.

2

Dual-Active-Bridge converter inductance DC-bias current compensation under low and high load conditions

Nalepa R., Zygmanowski M., Michalak J.

Przegląd Elektrotechniczny

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2018

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R. 94, nr 7

1--5

EN

Operation of the Dual-Active-Bridge converter in steady state and dynamic conditions are presented in this paper basing on a simulation model taking into account the bridge inductance DC-bias current driven by the volt-second unbalance within PWM cycles. In the paper the bridge operation within the output power range from <1% to the 100% is presented under: a) basic output voltage closed loop control, b) output voltage with proposed DC-bias current compensation control strategies. At this stage of research power losses generated inside of the converter have not been taken into account.

PL

W artykule prezentuje się pracę przekształtnika typu DAB zarówno w stanie ustalonym jak i stanach dynamicznych bazując na modelu symulacyjnym w którym uwzględniono możliwość występowania składowej stałej prądu dławika spowodowanej niezerową wartością średniej bieżącej jego napięcia. W artykule analizuje się pracę w zakresie mocy równych od <1% do 100% mocy znamionowej gdy przekształtnik pracuje z a) podstawowym sterowaniem ze sprzężeniem od napięcia wyjściowego, b) sterowaniem napięcia wyjściowego z uwzględnieniem zaproponowanych metod kompensacji składowej stałej prądu. W pokazanej analizie nie uwzględniono strat mocy generowanych w przekształtniku.

3

Neuromechanical control in submaximal drop jumps: The effects of volitional effort demands and drop height magnitude on soleus muscle activation

Mrdakovic V., Pazin N., Vulovic R., Filipovic N., Ilic D.

Acta of Bioengineering and Biomechanics

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2018

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Vol. 20, no. 4

101--111

EN

The purpose of this study was to investigate soleus muscle activation during different phases of drop jump performed at submaximal levels of volitional effort and drop height magnitude. Methods: Fifteen professional volleyball players with minimum of eight years of experience in jumping activities participated in the study. Experimental protocol involved executing submaximal drop jumps at three levels of volitional effort (i.e., 65, 80 and 95% of the maximal height of jump). All submaximal drop jumps were done from three drop heights (20, 40 and 60 cm). The soleus muscle activation was monitored during four jump phases: pre-activation phase before touchdown, early contact phase upon touchdown, early and late push-off phase. Results: The results indicate that volitional effort level did not change the muscle activation during pre activation and early contact phase, but only in early and late push-off phase ( p ≤ 0.05). Conversely, it was observed that muscle activation during all phases of drop jump was adapted to the increased intensity of the external load caused by increasing of drop height magnitude ( p ≤ 0.01). Conclusions: The findings of the present study suggested that soleus muscle activation has selective responses to internal load (i.e., volitional effort level) and external load (i.e., drop height magnitude) intensities when drop jump is executing with submaximal effort.

4

Design of the control system for canned-food sterilization

Ryniecki A., Wawrzyniak J., Danyluk B.

Przemysł Spożywczy

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2015

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T. 69, nr 8

62--64

EN

A properly designed control system for canned-food sterilization is able to achieve the final desired level of bacterial inactivation, irrespective of any disturbances, e.g. in the form of undesired changes of the heating- medium temperature, and with a minimum of over-processing. The feed-forward control system for canned- food sterilization was described in the article. The controller in such a system is able: (a) to anticipate the change of the final cumulative lethality in a situation when the disturbances of the process occurred during heating and (b) to take appropriate corrective actions that can eliminate such disturbances. The heating turn-off decisions in such a controller are based upon the prediction (in every second during heating) of cumulative lethality for the cooling stage. The prediction of the cooling phase is based on a simulation of temperature changes in the coldest point inside a can using the empirical m-th order step-response model.

PL

Właściwie zaprojektowany system sterowania procesem sterylizacji konserw mięsnych umożliwia osiągnięcie zadanego końcowego poziomu inaktywacji bakterii niezależnie od zakłóceń, np. w postaci niepożądanych zmian temperatury medium grzejnego, przy równoczesnym zachowaniu warunku minimum nadmiernego wyjałowienia konserw. W artykule przedstawiono system sterowania procesem sterylizacji ze sprzężeniem wyprzedzającym. Sterownik tego systemu umożliwia: (a) przewidywanie zmian końcowej letalności skumulowanej w sytuacji, gdy zakłócenia procesu występują w czasie ogrzewania, oraz (b) wprowadzenie odpowiednich sygnałów korekcyjnych, eliminujących te zakłócenia. W tym sterowniku, decyzje o zakończeniu ogrzewania podejmowane są w każdej sekundzie ogrzewania na podstawie przewidywania wartości sterylizacyjnej fazy chłodzenia. Przewidywanie to realizowane jest przy wykorzystaniu symulacji zmian temperatury w najmniej dogrzanym miejscu konserwy za pomocą empirycznego modelu inercyjnego m-tego rzędu.

5

On suppression of chaotic motions of a portal frame structure under non-ideal loading using a magneto-rheological damper

Tusset A. M., Piccirillo V., Balthazar J. M., Brasil R. M. L. R. F.

Journal of Theoretical and Applied Mechanics

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2015

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Vol. 53 nr 3

653--664

EN

We consider chaotic motions of a portal frame structure under non-ideal loading. To suppress this chaotic behavior, a controlling scheme is implemented. The control strategy involves application of two control signals and nonlinear feedforward control to maintain a desired periodic orbit, and state feedback control to bring the system trajectory into the desired periodic orbit. Additionally, the control strategy includes an active magneto-rheological damper to actuate the system. The control force of the damper is a function of the voltage applied in the coil of the damper that is based on the force given by the controller.

6

Earplug Actuator Selection for a Miniature Personal Active Hearing Protection System

Pawełczyk M., Latos M.

Archives of Acoustics

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2010

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Vol. 35, No. 2

213-222

EN

There are many industrial environments which are exposed to a high-level noise. It is necessary to protect people from the noise. Most of the time, the consumer requires a miniature version of a noise canceller to satisfy the internal working place requirements. Very important thing is to select the most appropriate personal hearing protection device, for example an earplug. It should guarantee high passive noise attenuation and allow for secondary sound generation in case of active control. In many cases the noise is nonstationary. For instance, some of the noisy devices are switched on and off, speed of some rotors or fans changes, etc. To avoid any severe transient acoustic effects due to potential convergence problems of adaptive systems, a fixed-parameter approach to control is appreciated. If the noise were stationary, it would be possible to design an optimal control filter minimising variance of the signal being the effect of the acoustic noise and the secondary sound interference. Because of noise nonstationarity for most applications, the idea of generalised disturbance defined by a frequency window of different types has been developed by the authors and announced in previous publications. The aim of this paper is to apply such an approach to different earplugs and verify its noise reduction properties. Simulation experiments are conducted based on real world measurements performed using the G.R.A.S. artificial head equipped with an artificial mechanical ear, and the noise recorded in a power plant.

7

Optymalne sterowanie temperaturą i stężeniem dwutlenku węgla w wybranym procesie klimatycznym szklarni

Stankiewicz A.

Inżynieria Rolnicza

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2009

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R. 13, nr 9

273-281

PL

W pracy rozważa się zadanie równoczesnego sterowania temperaturą powietrza i stężeniem dwutlenku węgla wewnątrz szklarni dla wybranego, znanego w literaturze, systemu klimatycznego szklarni. Sterowanie realizowane jest w systemie sterowania typu feedback-feedforward, który pozwala w torze sprzężenia "wprzód" skutecznie i szybko kompensować skutki szybkozmiennych deterministycznych zakłóceń, a w torze sprzężenia zwrotnego od stanu procesu zapewnia szybkie zanikanie błędu sterowania. Macierz regulatora dobrano optymalnie w sensie całkowego wskaźnika kwadratowego z mnożnikiem czasowym. Wyniki eksperymentów przeprowadzonych z wykorzystaniem programu Matlab/Simulink dowodzą skuteczności zastosowanej struktury i algorytmu sterowania.

EN

The control of the temperature and carbon dioxide concentration inside the greenhouse is an important tool to control crop growth both in a qualitative as well as in a quantitative sense in view of the horticultural practice of modern greenhouses. The simulation experiments were conducted for simultaneous control of the temperature and carbon dioxide concentration for the known in the literature example of the production of a lettuce crop by the use of the Simulink toolbox of Matlab. The effectiveness of the model based feedback-feedforward control system is demonstrated for the state variables stabilization on piecewise constant user-desired or computed by the upper optimization level set-points.

8

O optymalnym sterowaniu temperaturą i stężeniem dwutlenku węgla w szklarni

Stankiewicz A.

Inżynieria Rolnicza

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2009

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R. 13, nr 8

189-198

PL

Systemy sterowania klimatem we współczesnych szklarniach to złożone struktury wykorzystujące model matematyczny sterowanego procesu i nowoczesne koncepcje sterowania. W pracy rozważa się zadanie równoczesnej stabilizacji temperatury powietrza i stężenie dwutlenku węgla wewnątrz szklarni przy odcinkami stałych wartościach zadanych. Zaproponowano nowy system sterowania typu feedback-feedforward, który pozwala w torze sprzężenia "wprzód" skutecznie i szybko niwelować skutki szybkozmiennych zakłóceń, a w torze sprzężenia zwrotnego od stanu procesu zapewnia szybkie zanikanie błędu sterowania. Macierz regulatora dobrano optymalnie w sensie wskaźnika z mnożnikiem czasowym.

EN

The optimal control of greenhouse climate has received considerable attention in agricultural engineering research. In this paper a new feedback-feedforward control system is proposed for the state variables stabilization on piecewise constant user-desired or computed by the upper level set-points for temperature and CO2 concentration. The proposed control structure consists of two main parts: a model based feedforward compensation of external disturbances and the model based optimal feedback simultaneous control of the greenhouse temperature and CO2 concentration. The applied decomposition is able to deal with rapidly fluctuating deterministic external inputs or disturbances acting on the system by feedforward static compensation and guarantee the fast decay of the control error due to the static state feedback with constant gain matrix optimal in the sense of timemultiplied quadratic index. In a forthcoming paper, the simulation experiments will be conducted for the known in the literature example of the production of a lettuce crop by the use of the Simulink toolbox of Matlab in order to demonstrate the effectiveness of the control system proposed.

9

Feedforward vs. Feedback Fixed-Parameter H2 Control of Non-Stationary Noise

Latos M., Pawełczyk M.

Archives of Acoustics

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2009

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Vol. 34, No. 4

521-535

EN

Stationary random noise can be modelled as a wide-sense stationary white noise filtered by a minimum phase filter. Such filter can be used to design an optimal control filter minimising variance of the signal being the effect of the noise and the secondary sound interference. However, in many environments the noise is subject to change. For instance, some of the noisy devices are switched on and off, speed of some rotors or fans changes, etc. As a result contribution of different frequency components may significantly vary in time. Solving the optimisation problem to update control filter is rather avoided in on-line systems. In adaptive approach there are problems with convergence or some unpleasant transient acoustic effects. In this paper, the fixed-parameter approach to control is appreciated. Dominating frequency components/bands can usually be distinguished for the acoustic environment. Then, the idea of generalised disturbance defined by a frequency window of different type can be applied. If a reference signal, correlated with the disturbance to be reduced is available in advance, a feedforward structure can be applied, and otherwise, a feedback structure is used. Spectral and inner-outer factorisations are employed in order to cope with non-minimum phase character of the acousto-electric plant. Efficiency of the proposed approach for both control structures is verified based on the data obtained from an active personal headset. The generalised disturbance based control systems are confronted with the classical Wiener control systems designed for the given disturbance.

10

Dynamics and Control of Robots with Parallel Kinematic Structures

Heimann B., Abdellatif H.

Machine Dynamics Problems

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2005

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Vol. 29, No. 4

59-68

EN

It is often, that the dynamics of parallel robots are mostly restricted to simple models to keep real-time capabilities in control systems. The here presented approach for modelling the dynamics takes especially into consideration real-time and parameter identification aspects. This formulation is automatically obtained by an algorithm, that utilizes Jourdain's principle of virtual power using operational space presentation. It leads to a formulation of the dynamic equations of minimal order. The use of linear estimators is based on a formulation of the dynamic equations, which is linear with respect to a dynamic parameter vector of minimal dimension. The principal design methodology for such machines with parallel kinematic structure is exemplarily discussed by consideration of two different machines: the robot "PaLiDA" and a hydraulic test stand "MSI" with 6 degree-of-freedom each. The experimental application of the identified model to model-based feedforward control of the innovative hexapod PaLiDA, which has been developed by the Institute of Production Engineering and Machine Tools of the University of Hannover, proves the capability and efficiency of the presented algorithms.

11

Stabilising solutions to a class of nonlinear optimal state tracking problems using radial basis function networks

Ahmida Z., Charef A., Becerra V. M.

International Journal of Applied Mathematics and Computer Science

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2005

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Vol. 15, no 3

369-381

EN

A controller architecture for nonlinear systems described by Gaussian RBF neural networks is proposed. The controller is a stabilising solution to a class of nonlinear optimal state tracking problems and consists of a combination of a state feedback stabilising regulator and a feedforward neuro-controller. The state feedback stabilising regulator is computed online by transforming the tracking problem into a more manageable regulation one, which is solved within the framework of a nonlinear predictive control strategy with guaranteed stability. The feedforward neuro-controller has been designed using the concept of inverse mapping. The proposed control scheme is demonstrated on a simulated single-link robotic manipulator.

12

Sliding mode control with directly learned feedforward compensation

Xu J.-X., Song Y.

Applied Mathematics and Computer Science

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1998

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Vol. 8, no 1

89-100

EN

A new control method synthesizing direct learning control (DLC) with sliding mode control (SMC) is proposed for the tracking problem of a class of non-linear high order systems. Sliding mode control is used to provide the control system with indispensable robustness in the presence of strong system uncertainties. A new learning control method, the direct learning control method, is developed and used to generate the desired feedforward compensation for SMC. It can be shown that the combined scheme can successfully retain the advantages of both control methods. By virtue of SMC, the global asymptotic stability is ensured. Meanwhile, DLC provides an effective way to anticipate the necessary control signals for a new trajectory in terms of past control profiles which may correspond to different trajectories. In comparison with SMC alone, the synthesized control scheme achieves higher tracking accuracy and smoother control efforts.