Due to its advantages like minimal trauma and a low risk of infections, the minimally invasive surgery (MIS) has become the standard operation technique for many surgical procedures. During this type ...of intervention, one of the main tasks from a technical point of view is the control of the pressure in the operation area in order to give the surgeon sufficient space to perform his actions. Because no invasive measurements are available, an extended Kalman filter incorporating the peristaltic behavior of the used medical device was developed to estimate the pressure in the operation area. This contribution focuses on the observer design while a separately designed PI controller using loop shaping was employed for validation. The proposed observer-based control structure was tested with a simulator deploying the principle of physical equivalence.
In the analysis of consensus problems for multi-agent systems affected by time delays, the delay margin for a given protocol is heavily dependent on the communication topology being used. This ...document aims to answer the question of what is the largest delay value under which convergence to consensus is still possible even if the communication topology is not known. To answer this question we revisit the concept of most exigent eigenvalue, applying it to two different consensus protocols for agents driven by second order dynamics. We show how the delay margin depends on the structure of the consensus protocol and the communication topology, and arrive to a boundary that guarantees consensus for any connected communication topology. The switching topologies case is also studied and It is shown that for one protocol the stability of the individual topologies is sufficient to guarantee consensus in the switching case, whereas for the other one it is not.
Multivariate statistical process monitoring (MSPM) methods are powerful tools for detecting faults in industrial systems. However, industrial processes are often subjected to dynamic changes. This ...dynamic behavior is mainly due to set-point changes and nonlinearities. Because of the nonlinearity of processes, the performance of the classical MSPM methods, which are mainly based on the linearity assumption, becomes unsatisfactory, since the process characteristics will change from one operating point to another. The main objective of the work is to develop an efficient fault detection technique for complex industrial systems, using process historical data and considering the nonlinear behavior of the process. In the proposed approach, the nonlinear system is assumed to be linear around the operating points and therefore considered as a piecewise linear system corresponding to each operating mode. The performance and effectiveness of this approach are demonstrated using data obtained from a paper machine and compared with an available method.
This paper presents methodologies for modeling navigation filters for a new type of underwater gliders. The presented glider breaks with the traditional concept of fixed wing gliders. Instead it ...achieves the desired angle of attack and glidepath with its passively adapting flapping wings, which allows for a travel on even keel. The glider is currently developed in the flying argo project by the university of rostock and BaltiCo GmbH at the ocean technology campus rostock. The key feature of the proposed methodologies is the combination of a motion model with traditional sensor fusion algorithms. The paper closes with simulation results comparing the different approaches.
An observer-based output feedback adaptive fuzzy controller is proposed to stabilize a class of uncertain chaotic systems with unknown time-varying time delays, unknown actuator nonlinearities and ...unknown external disturbances. The actuator nonlinearity can be backlash-like hysteresis or dead-zone. Based on universal approximation property of fuzzy systems the unknown nonlinear functions are approximated by fuzzy systems, where the consequent parts of fuzzy rules are tuned with adaptive schemes. The proposed method does not need the availability of the states and an observer based output feedback approach is proposed to estimate the states. To have more robustness and at the same time to alleviate chattering an adaptive discontinuous structure is suggested. Semi-global asymptotic stability of the overall system is ensured by proposing a suitable Lyapunov–Krasovskii functional candidate. The approach is applied to stabilize the time-delayed Lorenz chaotic system with uncertain dynamics amid significant disturbances. Analysis of simulations reveals the effectiveness of the proposed method in terms of coping well with the modeling uncertainties, nonlinearities in actuators, unknown time-varying time-delays and unknown external disturbances while maintaining asymptotic convergence.
Engine test beds are widely used to estimate automotive engine parameters and design controllers in the preliminary development phase. The controller parameters are optimized to fulfill emission, ...fuel consumption and driving comfort requirements and they will be further validated on chassis dynamometer and road driving experiments. It is common that the results of two experiments deviate, due to some external disturbances or faults. The main purpose of this paper is to demonstrate the application of data-driven fault diagnosis techniques to detect the deviations in the experiments and analyze their root-causes to reduce the costs and time of the engine design and its control concept. To this end, two different methods are introduced for detection of the problems in the experiment. Based on the results of the detection step, a fault isolation technique has been proposed to support test engineers in finding the cause of the deviations. The results have been demonstrated on an industrial engine test bed and the effectiveness of the methods is discussed.
The publication on hand presents the results of the ongoing developments of a modular fault detection algorithm for ROVs within the MiroBase Project. It is based on a multi-model approach that was ...developed, applied and tested in a MATLAB/Simulink environment. It is planned to test the implementation on a specific ROV under real conditions. The MiroBase project aims to provide a framework for modular ROVs. The modularity will allow different hardware and software configurations. In order to enable Fault Detection and Isolation (FDI) for these different configurations it is necessary to develop an algorithm that can be adapted quickly and easily. A further challenge is the possibly incomplete sensor equipment, which prevents complete monitoring of all components. This paper describes the following steps that are necessary to implement model-based fault diagnosis for ROVs: designing the model, generating residuals, calculating fault models, determining fault type and quantity.
The conventional approaches for modelling of charge cycle in combustion engines are based on first principles. In this approaches, it is necessary to estimate different parameters in engine, which is ...very difficult to implement in real-time. In addition, it requires a high parameterisation effort because of a variety of engine characteristics. The model is further used in engine control unit to improve the efficiency of the combustion. Moreover, it can be used for estimation of some physical variables in engine to increase the performance of the controller. It also avoids the installation of extra sensors and reduces the costs of production. In this study, two different data-driven modelling methods for estimation of air mass are investigated. They also offer a flexible modelling approach considering various options for equipment as well as sensors and actuators in the engines. Both data-driven methods, the Gaussian mixture regression (GMR) and the local linear model tree (LOLIMOT) algorithm, allow a flexible modelling with a high input space dimensionality, with sparsity of data, a good interpretability and also offer possibilities of adaptation and local optimisation. While the GMR uses a statistical approaches to train the model, in the LOLIMOT an incremental, heuristic approach is used. Both methods are applied to the data obtained from a spark-ignition engine and the results are compared and discussed.
From Manoeuvre Assistance to Manoeuvre Automation Schubert, Agnes U.; Kurowski, Martin; Damerius, Robert ...
Journal of physics. Conference series,
10/2019, Letnik:
1357, Številka:
1
Journal Article
Recenzirano
Odprti dostop
One of the greatest challenges in shipping automation is the automatic manoeuvring in areas with high safety standards which are executed today exclusively by nautical officers with appropriate ...expertise. Precise manoeuvre plans and suitable control solutions are missing because the human operators act according their mental strategies. The presented approach for automated manoeuvring primarily bases on a complex dynamic motion model of a specific vessel. This model is adapted and used to plan a complete manoeuvre sequence considering the common nautical guidelines and the vessel characteristics. The resulting digital manoeuvre plan forms the basis for the assistance during manual manoeuvring as well as the automatic manoeuvring. Prognosticated weather conditions can be involved already during the planning. For automatic manoeuvring, the deduced manoeuvre trajectory is implemented into the feed-forward part of velocity control. The entire control structure is cascaded in outer trajectory controller and inner velocity controller. The described approach was successfully applied for large vessels in ship handling simulator for automatic collision avoidance and port manoeuvres.
PDF
