<title>Performance of wavefront sensing and control algorithms on a segmented telescope testbed</title>

Submarine inspections and surveys require underwater vehicles to operate in deep waters efficiently, safely and reliably. Autonomous Underwater Vehicles employing advanced navigation and control systems present several advantages. Robust control algorithms and novel improvements in positioning and navigation are needed to optimize underwater operations. This paper proposes a new general formulation of this problem together with a basic approach for the management of deep underwater operations. This approach considers the field of view and the operational requirements as a fundamental input in the development of the trajectory in the autonomous guidance system. The constraints and involved variables are also defined, providing more accurate modelling compared with traditional formulations of the positioning system. Different case studies are presented based on commercial underwater cameras/sonars, analysing the influence of the main variables in the measurement process to obtain optimal resolution results. The application of this approach in autonomous underwater operations ensures suitable data acquisition processes according to the payload installed onboard.

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Design and Research on Power Systems and Algorithms for Controlling Electric Underground Mining Machines Powered by Batteries

Energies ◽

10.3390/en14134060 ◽

2021 ◽

Vol 14 (13) ◽

pp. 4060

Author(s):

Artur Kozłowski ◽

Łukasz Bołoz

Keyword(s):

Power Systems ◽

Power Supply ◽

Internal Combustion Engines ◽

Underground Mining ◽

Test Stand ◽

Research Network ◽

Control Algorithms ◽

Systems And Control ◽

And Control ◽

Supply Systems

This article discusses the work that resulted in the development of two battery-powered self-propelled electric mining machines intended for operation in the conditions of a Polish copper ore mine. Currently, the global mining industry is seeing a growing interest in battery-powered electric machines, which are replacing solutions powered by internal combustion engines. The cooperation of Mine Master, Łukasiewicz Research Network—Institute of Innovative Technologies EMAG and AGH University of Science and Technology allowed carrying out a number of works that resulted in the production of two completely new machines. In order to develop the requirements and assumptions for the designed battery-powered propulsion systems, underground tests of the existing combustion machines were carried out. Based on the results of these tests, power supply systems and control algorithms were developed and verified in a virtual environment. Next, a laboratory test stand for validating power supply systems and control algorithms was developed and constructed. The tests were aimed at checking all possible situations in which the battery gets discharged as a result of the machine’s ride or operation and when it is charged from the mine’s mains or with energy recovered during braking. Simulations of undesirable situations, such as fluctuations in the supply voltage or charging power limitation, were also carried out at the test stand. Positive test results were obtained. Finally, the power supply systems along with control algorithms were implemented and tested in the produced battery-powered machines during operational trials. The power systems and control algorithms are universal enough to be implemented in two different types of machines. Both machines were specially designed to substitute diesel machines in the conditions of a Polish ore mine. They are the lowest underground battery-powered drilling and bolting rigs with onboard chargers. The machines can also be charged by external fast battery chargers.

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A Tip–Tilt and Piston Detection Approach for Segmented Telescopes

Photonics ◽

10.3390/photonics8010003 ◽

2020 ◽

Vol 8 (1) ◽

pp. 3

Author(s):

Shun Qin ◽

Wai Kin Chan

Keyword(s):

Error Detection ◽

Phase Retrieval ◽

Dynamic Range ◽

Detection Accuracy ◽

Wavefront Sensing ◽

Next Generation ◽

Large Aperture ◽

Detection Approach ◽

Segmented Mirror ◽

And Control

Accurate segmented mirror wavefront sensing and control is essential for next-generation large aperture telescope system design. In this paper, a direct tip–tilt and piston error detection technique based on model-based phase retrieval with multiple defocused images is proposed for segmented mirror wavefront sensing. In our technique, the tip–tilt and piston error are represented by a basis consisting of three basic plane functions with respect to the x, y, and z axis so that they can be parameterized by the coefficients of these bases; the coefficients then are solved by a non-linear optimization method with the defocus multi-images. Simulation results show that the proposed technique is capable of measuring high dynamic range wavefront error reaching 7λ, while resulting in high detection accuracy. The algorithm is demonstrated as robust to noise by introducing phase parameterization. In comparison, the proposed tip–tilt and piston error detection approach is much easier to implement than many existing methods, which usually introduce extra sensors and devices, as it is a technique based on multiple images. These characteristics make it promising for the application of wavefront sensing and control in next-generation large aperture telescopes.

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Design and Simulation of Pedal Simulator in Brake by Wire System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.1358 ◽

2014 ◽

Vol 556-562 ◽

pp. 1358-1361 ◽

Cited By ~ 1

Author(s):

Wen Bo Zhu ◽

Fen Zhu Ji ◽

Xiao Xu Zhou

Keyword(s):

Simulation Models ◽

Control Algorithms ◽

Brake Pedal ◽

Braking System ◽

Pedal Force ◽

Performance Requirements ◽

System A ◽

Pedal Feel ◽

And Control ◽

Wire System

Wire of the brake pedal is not directly connected to the hydraulic environment in the braking By-wire system so the driver has no direct pedal feel. Then pedal simulator is an important part in the brake-by-wire system. A pedal force simulator was designed based on the traditional brake pedal curve of pedal force and pedal travel, AMESim and Matlab / Simulink were used as a platform to build simulation models and control algorithms. The simulation results show that the pedal stroke simulator and the control strategy meet the performance requirements of traditional braking system. It can be used in brake by wire system.

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Comparative studies of the set up of two-dimensional pneumatic arm systems by muscle and rotational actuators

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1243/09596518jsce413 ◽

2007 ◽

Vol 221 (5) ◽

pp. 743-748 ◽

Cited By ~ 1

Author(s):

Y-T Wang ◽

R-H Wong ◽

J-T Lu

Keyword(s):

Control Systems ◽

Fuzzy Controller ◽

Control Algorithms ◽

Two Dimensional ◽

Pneumatic Control ◽

Learning Mechanism ◽

Set Up ◽

And Control ◽

Self Learning ◽

System Characteristics

As opposed to traditional pneumatic linear actuators, muscle and rotational actuators are newly developed actuators in rotational and specified applications. In the current paper, these actuators are used to set up two-dimensional pneumatic arms, which are used mainly to simulate the excavator's motion. Fuzzy control algorithms are typically applied in pneumatic control systems owing to their non-linearities and ill-defined mathematical model. The self-organizing fuzzy controller, which includes a self-learning mechanism to modify fuzzy rules, is applied in these two-dimensional pneumatic arm control systems. Via a variety of trajectory tracking experiments, the present paper provides comparisons of system characteristics and control performances.

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