سید محمدرضا ستاینده

There is no determined method for Micro Air Vehicles (MAVs) design (unlike full-scale aircraft), so MAVs design is very complex and vague. For this reason, the design of MAVs is very expensive (time-consuming), and finally, the obtained design could not be more optimal. To solve these challenges, this study developed a framework for Multidisciplinary Design Optimization (MDO) of fixed-wing MAVs. This framework aims to use the benefits of MDO (time reduction and achieving optimal design) in the design process of MAVs. So, it is tried to consider the most important modules for analysis, and the framework can consider all flight phases in the design optimization process. Geometry, weight, the center of gravity, aerodynamics, and power are the considered modules in this framework. The analysis of all modules is performed for the entire flight phase. To show the performance of this framework, the design optimization of a fixed-wing MAV has been done by considering take-off weight and drag as objective functions.  The considered constraints for this research are from stability and geometry modules. It is worth noting that with attention to the complex design space of MAVs and the capability of the Genetic Algorithm (GA), this algorithm has been considered as an optimization algorithm in this study.

In a holistic design; Creating a common language between different engineering, taking in to account the designer/customer's interests and preferences, removing potential shortcomings of common design methodologies and taking full advantage of the benefits of MDO approaches are the most important factors for achieving logical and realistic results. In this paper, a novel Comprehensive Preference-based Design approach is presented which attempts to achieve subjective attributes that are defined in the concept of maximization of designer/customer's satisfaction in addition to objective goals which are formulated in the form of minimization of a performance criterion in a two-phase structure using two nested optimizers. In the first phase of CPD, using the concept of satisfaction, the subjective preferences of the designer/customer are defined in terms of fuzzy relationships and operators in the form of demands and desires. Whereas the results of this phase are inaccurate, in the second phase, it is attempted to define a performance criterion and in order to achieve an optimal operational plan, attitude parameters and the compromises needed to meet the designer/customer's preferences are implemented. The methodology is utilized to design of a UAV with flight duration of 24 hours, 45 m/s of cruise speed at least, payload of 200 kg and less than 1 km take-off distance. To evaluate the results of CPD, the design process using MDO in AAO framework is also performed. Comparison of the results shows that despite the higher mass of UAV designed by CPD, overall satisfaction is higher and preferences have been satisfied.

In this paper, a comprehensive structure is expressed for multidisciplinary design optimization of the unmanned air vehicle and the design optimization of Predator MQ-1 has been studied for validation. The considered modules in the multidisciplinary analysis are performance, aerodynamic, weight, center of gravity, stability and control derivatives, trim and dynamic stability characteristics. The minimization of take-off weight and cruise drag are considered as objective functions. Since two objective functions are considered, therefore multi-objective genetic algorithm (with the non-dominated sorting concept) is used as optimizer which can generate set of optimal solutions as Pareto fronts. A method based on fuzzy logic named satisfaction degree function is expressed for final solution selection. The strengths of this paper are its comprehensiveness (the number of design modules, the number of design variables and constraints) and the presentation of a simple and efficient method for final solution selection. The optimization results show the effectiveness of the structured framework and suggested method.

In this study, a new guidance law for high maneuver targets is designed by using state dependent Riccati equation. The reason of using this equation is: no need to linearization of equations and simplification of implementation. The aim of this research is presenting a guidance law that compensate the depletion of classic guidance laws for high maneuver targets and in the second, the comparison among proportional navigation law, pure pursuit law and new guidance law. It is worth noting that the criterions of analyzing are: total of incoming acceleration and required time for hitting the target. So these laws have been compared for fixed target, moving target with constant speed and moving target with variable speed and for different initial conditions. Finally a sensitivity analysis has been done for investigation of laws behavior.

In this paper, behavior of the aircraft with flexible wing in dealing with atmospheric disturbances has been modeled and analyzed. In this research, material of wing is metal and wing has been modeled as a thin-walled (wing box), as well as wing mass distribution, shape modes and frequency is calculated by lumped mass and assumed mode shape method. For analyzing the effect of aircraft mass on the vehicle behavior, four models with different mass are simulated until critical condition is determined. Atmospheric disturbance is a undesirable input to aircraft dynamic where decrease flight safety therefore, the effect of this phenomena are analyzed as a random input on aircraft behavior. The using model for atmospheric disturbance is Monte Carlo model where the method of modeling is submitted. The effect of this disturbance has been simulated in two conditions. In the first simulation, intensity of turbulence is 100 ft/sec and intensity of the second simulation is 400 ft/sec until the turbulence that makes instability is assigned.