Due to its wide applications in different missions, identification of mathematical models of Unmanned Aerial Vehicles (UAVs) from flight test data becomes necessary for development of observers for states estimation, computer simulation, systems analysis, and in particular for autonomous flight control laws design. For an arbitrarily chosen aerial vehicle, Trex-700E -a single-rotor unmanned helicopter, a Low Order Equivalent System (LOES) model in longitudinal and lateral channels is identified respectively by utilizing CIFER ® system identification techniques. The flight test data is obtained at MicroPilot Inc. site by implementing piloted frequency sweep cyclic and collective inputs. Firstly, this paper presents a spectrum analysis performed on the input excitation signals of the flight tests.Secondly, non-parametric frequency-response models for on-axis longitudinal and lateral responses are acquired. Finally, a second-order transfer function model is identified for the longitudinal and lateral response respectively. The results show that LOES model for shortperiod mode can effectively predict the UAV system's relevant response. However, for lateral mode, the identified LOES model needs to be modified further with more flight test data. Nomenclature= vector of parameters to be estimated = cost function of parameter estimation = transfer function value evaluated in frequency and vector of estimated parameters = experimentally-determined frequency-responses evaluated in frequency = cost function weighting coefficient = equivalent time delay for the lumped effect of rotor and control system dynamics = equivalent time delay for effect of actuator and linkage dynamics = rotor time constant = short-period damping ratio = short-period undamped natural frequency = rotor-flap stiffness = lateral input gain = longitudinal input gain

Environmental simulation has an essential contribution in attitude determination and control verification tests of satellites. Specifically, real-time modeling of space environment can provide more precise and adapted simulation of real world in order to enable satellite attitude determination system by online outputs of sensors. Design and manufacturing of a moving mechanism which simulates the motion of real Sun relative to the satellite is proposed in this paper. Indeed, an artificial Sun carried by the mechanism will sensitize Sun Sensors mounted on a 3DOF model of satellite and finally the outputs of sensors are used to determine the attitude of the model satellite. The procedure of designing and manufacturing such a mechanism is described as follows. Firstly, the motion of Sun relative to the satellite on a specific orbit was ascertained. Next, considering the constraints such as laboratory space and its equipments, an appropriate mechanism was designed conceptually to satisfy the requirements. Then, the detailed characteristics of the mechanism were determined in the preliminary design phase and approved in the detailed design phase of the project. Finally, in order to verify the designed mechanism, a scaled down prototype was fabricated. Developmental tests on the prototype proved the ability of the model to simulate the Sun motion relative to the satellite properly.