scholarly journals Control torque generation of a CMG-based small satellite with MTGAC system: a trade-off study

Author(s):  
M B Salleh ◽  
N M Suhadis ◽  
P Rajendran ◽  
N M Mazlan
2019 ◽  
Vol 16 (1) ◽  
pp. 172988141882396 ◽  
Author(s):  
Ali Roshanbin ◽  
André Preumont

This study describes the design, development, and flight tests of a novel control mechanism to generate yaw control torque of a hovering robotic hummingbird (known as Colibri). The proposed method generates yaw torque by modifying the wing kinematics while minimizing its influence on roll and pitch torques. To achieve this, two different architectures of series and parallel mechanisms are investigated; they are mathematically analyzed to investigate their behavior with respect to cross-coupling effects. The analysis is verified by measuring the control torque characteristics. The efficacy of the proposed method is also explored by flight experiments.


2012 ◽  
Vol 225 ◽  
pp. 458-463 ◽  
Author(s):  
Nurulasikin Mohd Suhadis ◽  
Renuganth Varatharajoo

In this paper, the Proportional-Derivative (PD) based attitude control algorithm of the gravity gradient stabilized satellite has been developed. The satellite is equipped with 3 magnetic torquers where each of the magnetic torquer is placed along the +x, +y, +z axes. The control torque is generated when the magnetic field generated by the magnetic torquers couples with the geomagnetic fields, whereby the vector of the generated torque is perpendicular to both the magnetic fields. The developed control algorithm was simulated using the complex and simplified geomagnetic field models for a Low Earth Orbit (LEO) satellite mission in a nominal attitude operation. Results from simulations exhibit the effectiveness of the attitude control torque generation that fulfills the mission attitude control requirements.


Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1297
Author(s):  
Safarbek Oshurbekov ◽  
Vadim Kazakbaev ◽  
Vladimir Prakht ◽  
Vladimir Dmitrievskii

Reliability, along with energy efficiency, is an important characteristic of pump units in various applications. In practical pump applications, it is important to strike a balance between reliability and energy efficiency. These indicators strongly depend on the applied control method of the pump unit. This study analyzes a trade-off method for regulating a system with three parallel pumps equipped with only one frequency converter (multi-pump single-drive system). A typical operating cycle of a pumping system with variable flow rate requirements is considered. The proposed trade-off method is compared with the traditional regulation, when a change in the operating point of the pump is achieved only by changing the rotation speed, and with the method for maximum reliability. It is shown that the proposed trade-off method makes it possible to ensure sufficient reliability of the multi-pump system operation without a significant increase in energy consumption.


2021 ◽  
Author(s):  
G. Governale ◽  
J. Rimani ◽  
N. Viola ◽  
V. Fernandez Villace

AbstractThe trend of cost-effective access to space and satellite technologies’ evolution is increasing the small satellite market. However, small payloads usually ride as piggyback, being a secondary passenger of a space vector, with very low flexibility in target orbit and launch schedule. The micro-launchers are designed to answer the needs of the small satellite missions, with a payload capacity up to 350 kg to Low Earth Orbit, aiming to low turn-over time and competitive prices. This paper explains the work performed by Politecnico di Torino in support of the ESA–ESTEC activities on micro-launchers. The aim is to provide preliminary guidelines for choosing and evaluating new innovative micro-launcher flight vehicle engineering processes. A trade-off methodology is proposed and defined based on the Analytically Hierarchical Process (AHP). This methodology considers, among other features, the flight profile, maximum payload, and physical characteristics. To support the trade-off analysis, a software tool is built for the automatic generation of the aerodynamics and propulsion parameters needed for the completion of the preliminary designs, enabling the performance estimation. The launcher’s performance models, with an analysis of the take-off sites and target orbits, are also produced. This allows the definition of performance maps where the maximum payload is graphed as a function of the orbit altitude and inclination. A set of innovative micro-launchers exploiting different technologies is also assessed as a case study.


Author(s):  
Hans Fehr

SummaryThis paper examines the distributional and efficiency effects of pension privatization in Germany. Starting from a benchmark that reflects the current unfunded pension system, a fully funded system is introduced. The accrued benefits of the old system are financed by alternative tax combinations as well as deficit increases. The quantitative analysis is based on an Auerbach-Kotlikoff type simulation model that distinguishes between five lifetime income classes within each age cohort. The simulations reveal a clear trade-off between the efficiency and equity aspects of alternative financing schemes. While consumption taxes are the most efficient financing instrument, they also undermine intra- and intergenerational equity. Phasing-out the unfunded system on the other hand not only dampens the income redistribution across and within generations, but also reduces the efficiency gains dramatically.


2021 ◽  
pp. 197-210
Author(s):  
Matthew S. Shugart ◽  
Matthew E. Bergman ◽  
Cory L. Struthers ◽  
Ellis S. Krauss ◽  
Robert J. Pekkanen

In Britain’s first-past-the-post (FPTP) system—an exclusively single-seat-district system—every member of the House of Commons is elected in a unique geographically defined single-seat district. The FPTP system thus maximizes the importance of the geographic location of votes to party seat maximization. Yet as a single-tier system with no intraparty competition, it also promotes reliance on the expertise model, as the party seeks to emphasize its national policy reputation. Given the crucial role of districting in such a system, a party is expected to trade off reliance on the expertise model in order to deploy its personnel to Select Committees as a means to maximize the party’s chances of holding marginal (swing) districts. The findings show that the expertise model holds more strongly for the Conservative Party, and more weakly for the Labour Party, with the reverse pattern holding for the electoral–constituency model. Both parties show a high tendency toward issue ownership.


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