A fast integrated device for detection of connections and interns defects in aeronautical structures

The objectives are the fast detection (in real time) of beginning of internal elements defects and connections defects. The method is based on the fact that structure behaviours during its phase of excitation and afterwards, constitute powerful indicators of the quality of the limiting conditions or internal damage. It requires integration of a small number of sensors. Our study aimed deducing some criteria concerning these conditions and proposing an original exploitation

Self-organizing robot formations using velocity potential fields commands for material transfer

Mobile robot formations differ in accordance with the mission, environment, and robot abilities. In the case of decentralized control, the ability to achieve the shapes of these formations needs to be built in the controllers of each autonomous robot. In this paper, self-organizing formations control for material transfer is investigated, as an alternative to automatic guided vehicles. Leader–follower approach is applied for controllers design to drive the robots toward the goal. The results confirm the ability of velocity potential approach for motion control of both self-organizing formations

Real-Time Temperature Control of Thin Plates

Abstract -In this paper is investigated the control of the temperature on one side of the plate from the opposite side. To solve this problem, Laplace transform is used to obtain the quadrupole model of the direct heat equation and the analytical solution for the transfer function for the inverse problem. The resulting hyperbolic functions are approximated by Taylor expansions and the real-time open loop temperature control to a desired value is formulated. This approach is different from previous regularization methods of ill-posed problem and is suitable for real-time temperature control. Simulation results show the advantages and limitations of using inverse problem to control temperature of a plate

Nonlinear Robust Adaptive Multi-Modal Vibration Control of Bi-Electrode Micro-Switch with Constraints on the Input

Micro functionally graded material (FGM) structures are able to have proper functions in vast environments. In this paper, nonlinear governing equations of the size-dependent micro-switch are derived using modified couple stress theory. Effective external forces including fringing field of electrostatic force and Casimir force are considered. Two electrodes cooperate to track the in-plane motions of the micro continuous system by tuning the supply voltages of the electrostatic force. An adaptive projection law is proposed to compensate for the effect of error in the initial estimates of system parameters. To achieve more reliability, a robust active vibration strategy is presented to withstand external disturbances. At any time, just one electrode is operational, and optimization is performed to decrease the controller gains. The highly nonlinear inputs have a singularity in the dynamics of the system, which are known as pull-in instability, so for safety, the controller gains are chosen such that the pull-in voltage is avoided. The dynamic response of the system is simulated using a single mode or multiple modes to validate the effectiveness of the presented vibration control approaches. The effects of error of the initial estimate of system parameters, the effect of impulse and the influences of various volume fractions are studied

Gearbox fault diagnosis via generalized velocity synchronous Fourier transform and order analysis

Gearbox plays an essential role in many industrial equipment. Fault detection for gearboxes is very important yet extremely difficult due to the volatile working conditions which lead to non-stationary vibration signals. Order tracking is considered as a classic and effective technique for non-stationary vibration analysis and fault diagnosis of rotating machinery. To date, many order tracking methods that do not require a tachometer have been proposed, such as the resampling-based methods. However, most of them are complex and often introduce interpolation errors. To avoid such difficulties, a simple yet effective method is proposed in this paper. This method employs the generalized demodulation approach to extract a component whose frequency is proportional to the instantaneous shaft rotational frequency from the vibration signal, followed by demodulating the extracted component to recover the instantaneous shaft rotational phase. With such information the order spectrum can be directly obtained via the velocity synchronous discrete Fourier transform and finally the fault can be diagnosed by order spectrum analysis. The effectiveness of this method is validated by both simulated and lab experimental vibration signals of gearbox under time-varying rotational speed conditions.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Closed - Loop control of plate temperature using inverse problem

In this paper the temperature at one side of a plate is used to control in closed loop the temperature on the opposite side of the plate. To solve this problem, Laplace transform is used to obtain the quadrupole model of the direct heat equation and the analytical solution for the transfer function for the inverse problem. The resulting hyperbolic functions are approximated by Taylor expansions to facilitate the real-time closed loop temperature control formulation. Simulation results illustrate the advantages and permit to identify the limitations of using inverse problem to closed loop control temperature of a plate

Experimental verification for closed loop control of thin plate surface temperature

Thin plate surface temperature control is investigated using inverse problem in a closed loop control approach. This was achieved by solving the periodic boundary one-dimensional heat conduction equation, using Laplace transform, to get the transfer function for both direct problem and inverse problem. The resulting transfer functions were processed using Zero-Pole expansion to get a polynomial transfer functions for facilitating the simulation. After the simulation study of the closed loop temperature control, a closed loop experimental approach was developed using the inverse problem from simulation and connecting the results with a physical system by replacing the simulated direct problem. Experimental results were compared to previous simulation results