Simulation and Analysis of Electro Mechanical Actuator with Position Control

In recent times, Electro-Mechanical Actuator (EMA) is widely employed in various aerospace applications because of its compactness, ease of maintenance, and cost efficiency. It attracts most of the researcher for simulation and performance analysis. It is very much important to study its control system behaviour. In general, EMA requires, three loop cascade control, but for aerospace application two loop cascade control is used for speed and position controls due to dynamic load changing requirement. Most research efforts on EMA system has used a transfer function model of all its subsystems. Nevertheless, this technique does not yield complete outcomes for analysing its performance. To analyse its performance and characteristics in dynamic condition, an experimental model is essential. In addition, this model needs to cater for analysing performance of different capacity EMA. The primary goal of this work is to simulate unique EMA model with position control using a practical data and analyse its performance. In this design, EMA is modelled by three-phase Brushless Direct Current (BLDC) motor, six-step commutation logic, a speed sensor (Tacho) and a position sensor using Linear Variable Differential Transformer (LVDT). Position and speed controls are handled by Proportional (P) and Proportional plus Integral (PI) controllers respectively. The process reaction curve method is used to tune the controllers. This tuning approach is adequate to enable accurate and robust speed and position control. This paper focus on the simulation and performance analysis of a practical EMA system with position and speed controls in matlab-simulink. The performance analysis results shows that simulated model characteristic is close to physical system and reliable

Analysis of acoustic back scattered signals of two different underwater materials using Empirical Mode Decomposition and support vector machine

656-664<span style="font-size:10.0pt;font-family: " times="" new="" roman","serif";mso-fareast-font-family:"times="" roman";mso-bidi-font-family:="" mangal;mso-ansi-language:en-gb;mso-fareast-language:en-us;mso-bidi-language:="" hi"="" lang="EN-GB">In this work an attempt has been made to analyse and discriminate acoustic backscattered signals from underwater objects of two different materials of PVC and Brass. A laboratory study of underwater acoustic scattering of spherical objects of PVC and Brass material is carried out using Empirical Mode Decomposition (EMD), HilbertTransform (HT) and Support Vector Machine (SVM). Incident signal used for the measurement is a Linear Frequency Modulated (LFM) signal of finite duration with the signal bandwidth of 40 kHz to 80 kHz. More than 80 back scattered acoustic signals from the objects are recorded and processed for discrimination. An EMD method is designed to decompose the scattered signal and HT was used to extract the features for discrimination. EMD decomposes the backscattered signal into intrinsic mode functions ((IMFs) and the significant features are extracted from the HT. The classification or discrimination is investigated using support vector machine (SVM) with four types of kernels such as linear, quadratic, RBF and polynomial.  Performance of the SVM shows that the proposed method using EMD and Hilbert transform is useful for underwater object discrimination.</span