In design of defense structures, concrete are often used to provide protection against incidental dynamic loadings such as the impact of a steel projectile. In the present study, a new analytical model is proposed to predict penetration depth into concrete targets by og More
In design of defense structures, concrete are often used to provide protection against incidental dynamic loadings such as the impact of a steel projectile. In the present study, a new analytical model is proposed to predict penetration depth into concrete targets by ogive nose projectile. Hence, to develop the model and simulate penetration of high velocity ogive-shape nose steel projectiles into concrete targets, several tests has been simulated numerically with the Ls-Dyna finite element code. The results show good agreement with the analytical analyses and experimental results from other researchers.
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The Transfer functions of missiles change during flight. For proper control and desired performance of missiles through different situations during flight, their aerodynamic derivatives and mass inertia parameters need to be corrected at different working points. In thi More
The Transfer functions of missiles change during flight. For proper control and desired performance of missiles through different situations during flight, their aerodynamic derivatives and mass inertia parameters need to be corrected at different working points. In this paper the feedback of the tail flap vibrations are used to specify the gains and the aerodynamic parameters of a surface to air missile, for use in the transfer functions. The vibration characteristics of the tail flaps are usually good index of the missile’s speed and consequently its dynamic pressure which, can be used for aerodynamics and gain correction in different working points in the transfer functions. The vibration feedback from the tail flaps were used in a six degree of freedom missile simulation integrated with the tail flaps vibration model and the IMU model. Simulation results and its comparison with recorded results from test flights, shows that the vibration feedback from the tail flaps can quite adequately be used for estimation of missile speed, dynamic pressure, and correction of aerodynamic parameters of the transfer functions.
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A robot detects its surroundings through camera information and its response requires a high-speed image process. Due to the increasing application of vision systems, various algorithms have been developed to increase speed of image processing. This paper proposes a dou More
A robot detects its surroundings through camera information and its response requires a high-speed image process. Due to the increasing application of vision systems, various algorithms have been developed to increase speed of image processing. This paper proposes a double density Discrete Wavelet-based Neural Network to enhance feature extraction and classification of parts in each picture. The Discrete Wavelet-based Neural Network combines multi-scale analysis ability of the wavelet transform and the classification capability of the artificial neural network by setting the wavelet function as the transfer function of the neural network. The automatic assembly process needs to capture the image in an online process in order to recognize the parts in the image and identify the location and orientation of the parts. In this part, the two dimensional double density discrete wavelet transform have been applied to compress and remove noise from the captured Image. By applying a value for the threshold, the coefficients of the wavelet transform function are obtained using these coefficients and the characteristics of the wavelet coefficients are calculated. Subsequently, a multilayer perceptron is trained using these extracted features of the images. To find the best vector characteristics, various combinations of extracted properties have been investigated. This method has succeeded in object detection and results show that the Neural Networks and the training algorithm based on the wavelet transform function have exquisite accuracy in classification. Thus, the developed method is considered effective as compared to other state-of-the-art techniques.
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In this paper, a joint position-force controller is used to control a 6R general-purpose robot manipulator. The manipulator comes into interaction with a spherical object in a numerically simulated environment. A controller has been implemented using the MATLAB Simulink More
In this paper, a joint position-force controller is used to control a 6R general-purpose robot manipulator. The manipulator comes into interaction with a spherical object in a numerically simulated environment. A controller has been implemented using the MATLAB Simulink software which uses the Simmechanics second-generation toolbox. A useful numerical contact model is used for modelling the interaction between the manipulator’s end-effector and the environment which generates the interaction feedback forces. The control algorithm presented in this paper is developed in the Cartesian space and the original control algorithm was modified to satisfy the desired input position in the base coordinate frame. The control algorithm was verified using a virtual environment, before hardware implementation. The novelty of the controller is determining the input tactile forces for the robot without actually causing a collision between the end-effector and the object in the environment which can lead to fracture and damage to the environment or the manipulator. The modeling process of interaction with the spherical environment was investigated using Simmechanics to model precise mechanical characteristics of manipulator that are unknown to the designers and provide a great advantage in the simulation for them. The considered position and tactile force were tracked successfully with good accuracy. The results show that the proposed manipulator system controls the position and force with more than 95% accuracy and the accuracy of desired tracing trajectory is 99%.
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