The purpose of this paper is to present a method for development of the optimal speed-dependent control matrix for a rotor supported on active magnetic bearings (AMBs) with the provision of minimum control power consumption over the operating speed range. The speed dependency of the optimal control matrix is the result of the dynamics of rotating machines. Most of published works on optimal control use a stationary optimal control matrix derived for the non-rotating system and thus neglecting the effect of gyroscopic phenomena. This paper employs the minimum energy consumption condition to derive the speed varying optimal control for rotating AMB rotor system. In the presented approach the control matrix is characterized by a second order polynomial matrix with the angular speed as a variable. This leads to a more compact and lower computational burden for controller implementation. Calculations are performed for a 4-axis AMB rotor test rig. Testing with rotor speed ramps is performed and experimental values for power consumption are presented. These results are compared to results with speed invariant optimal control and PID control.

The goal of this paper is to study the dynamics of a quadcopter using a variable geometry structure and discuss the advantages of using the geometry variation. A mathematical model has been described using simulation to show quadcopter dynamics. Based on the different geometric configurations of arms it is shown how the arms’ angles affect longitudinal and lateral dynamics. The design's assumptions refer to hovering and rotation with Euler angles. Simulation results show that both controllers stabilize the quadrotor and the amplitude of the vibrations is significantly decreased, compared to the vibration of a common quadcopter with fixed arms, by varying the arm's angle. The quadcopter remains stable and all Euler rotations are perfectly controlled.

This work studies the impact conditions between the adolescent pedestrian and the bus focusing on head and chest injury. The injury to the head is analyzed using both the Head Injury Criterion (HIC) 36 and the HIC15 parameters as established by the most advanced legislation and comparing the risk probability Abbreviated Injury Scale (AIS3+) and AIS4+. The parameter HIC15 gives a higher probability of risk with lower values, and therefore it can be considered more conservative. Moreover, the study of chest injury is performed with two different biomechanical parameters: the Thoracic Trauma Index (TTI) and the TTI(d); the last neglects the pedestrian mass. The results indicate that the parameters are equivalent for the assessment of chest injury. Instead the front pedestrian collision is characterized by 3 ms criterion. The results comparison with those obtained previously with other types of vehicles shows that, in all cases, the impact with the bus is most dangerous for the teenage pedestrian because of the higher values of the biomechanical parameters. Finally, the influence of the vehicle mass has been investigated, emphasizing how it cannot be neglected a priori. Numerical analysis results are in very good agreement with the results carried out experimentally, from several authors, in real accidents where buses are involved.

The purpose of this paper is to propose a useful method to implement active magnetic bearings (AMBs) on an existing\ud rotating shaft which rotates on conventional bearings. This is feasible if AMBs can produce the same reaction loads of\ud conventional ones and if the size of vane is large enough to host an AMB. As this substitution could offer some difficulties\ud due to the different size between magnetic bearings and conventional ones, a set of equations are performed to show\ud that a variation of some parameters can solve this problem. The journal ratio is the geometrical parameter introduced to\ud develop the present analysis. The variation of journal ratio does not produce a variation of the pole’s surface so that the\ud reaction load does not change. The results are analyzed by numerical analysis by mathematical relationships involving the\ud design parameters, magneto-static simulations and dynamic simulation on shaft when it is tested by disturbance rejection\ud and reference tracking input in order to analyze the differences on dynamic behavior of the shaft on its suspended\ud sections. Results show that the displacement pattern of the suspended sections remains unchanged, confirming that the\ud reaction load, produced by pole expansion, remains the same varying the journal ratio