Sharif Digital Repository

The control of a brachiation robot has been the primary objective of this study. A brachiating robot is a type of a mobile arm that is capable of moving from branch to branch similar to a long-armed ape. In this paper, to minimize the actuator work, Pontryagin's minimum principle was used to obtain the optimal trajectories for two different problems. The first problem considers brachiation between fixed branches with different distance and height, whereas the second problem deals with the brachiating and catching of a moving target branch. Theoretical results show that the control effort in the proposed method is reduced by 25% in comparison with the target dynamics method which was proposed... 

This paper presents two effective methods to reduce power consumption of branch target buffer (BTB): 1) the first method is based on storing distance to next branch address in tag array instead of storing whole branch address, 2) the second method is to use a new field in data array of BTB namely Next Branch Distance (NBD) which holds distance of next branch address from current branch address. When a new hit is performed in BTB, based on NBD field, there would be no access through NBD number of instructions, so BTB can be shutdown not to consume power. The new architecture does not impose extra delay and reduction in prediction accuracy. Both methods were implemented and simulated using... 

Exploiting Compressive Sensing (CS) in MIMO radars, we can remove the need of the high rate A/D converters and send much less samples to the fusion center. In distributed MIMO radars, the received signal can be modeled as a block sparse signal in a basis. Thus, block CS methods can be used instead of classical CS ones to achieve more accurate target parameter estimation. In this paper a new method of energy allocation to the transmitters is proposed to improve the performance of the block CS-based distributed MIMO radars. This method is based on the minimization of an upper bound of the sensing matrix block-coherence. Simulation results show a significant increase in the accuracy of multiple... 

In this paper, the effect of the main rotor of an armed helicopter on radar return signal and its modulation condition are considered. After analyzing references and experimental data, this paper proposes a new method based on inherent modulation in main rotor echo. This method is able to enhance the probability of detection. The simulation is performed for both simulated and practical echo signal. Simulation results confirm that our proposed scheme is effective. Moreover, a new domain for distinguishing and measuring the rotation feature of a rotary target is proposed. This paper is based on practical experiments (rotation domain)  

A robust target recognition method proposed based on recurrence plot and recurrence quantification analysis (RQA) to generate robust features against noise, target velocity and aspect angle from micro-Doppler (m-D) signatures. The proposed method is tested on simulated data of three different targets using multiclass support vector machine (MSVM) and classification rate of about 95 % is achieved. Also, effect of noise and coherent processing time (CPT) on classification rate is investigated  

Human–robot interaction is an important issue in robotic researches which is the key in many rehabilitation and robot-assisted therapy applications. Impedance control can properly handle soft interaction of robots with the environment. Optimal target impedance selection can increase the performance of the overall system and guarantee the stability. The target impedance cannot be selected without proper knowledge about the stiffness and inertia parameters of the human. In this paper, a systematic analysis is done to introduce a method to estimate the human stiffness and consequently adjust the robot target stiffness. Then, particle swarm optimization is used to find the damping and inertia... 

This study presents and analyses a novel joint detection and parameters estimation of multiple targets using a co-located multiple input/multiple output radar with moving platform, in the presence of clutter and background noise. A notable feature of the proposed approach is that clutter cancellation is independent of received data. Moreover, to decrease the computational load, the authors propose to perform the target detection and parameters estimation by directly processing on the compressive measurements as opposed to Nyquist samples. © The Institution of Engineering and Technology  

Multiple input multiple output (MIMO) radar is known for its superiority over conventional radar due to its antenna and waveform diversity. Although higher angular resolution, improved parameter identifiability, and better target detection are achieved, the hardware costs (due to multiple transmitters and multiple receivers) and high energy consumption (multiple pulses) limit the usage of MIMO radars in large scale networks. On one hand, higher angle and velocity estimation accuracy is required, but on the other hand, a lower number of antennas/pulses is desirable. To achieve such a compromise, in this work, the Cram'er-Rao lower bound (CRLB) for the angle and velocity estimator is employed... 

Multiple-input multiple-output (MIMO) radar is known for its superiority over conventional radar due to its antenna and waveform diversity. Although higher angular resolution, improved parameter identifiability, and better target detection are achieved, the hardware costs (due to multiple transmitters and multiple receivers) and high-energy consumption (multiple pulses) limit the usage of MIMO radars in large scale networks. On one hand, higher angle and velocity estimation accuracy is required, but on the other hand, a lower number of antennas/pulses is desirable. To achieve such a compromise, in this paper, the Cramér-Rao lower bound (CRLB) for the angle and velocity estimator is employed... 

A new method based on Hough transform is introduced for detection of linear trajectories in a 3-D data space. Data space is constructed from returned radar data using range, bearing, and time information. This information is then mapped into a 3-D Cartesian data space. The near constant velocity target trajectories appear as straight lines in this space, and are detected by the usage of the new method which is based on two 2-D Hough transforms in the bearing-time and range-time data spaces. The efficacy of this Combinational Hough transform method is verified by simulation and shown that it has a better performance, as compared with one 2-D data map case, where only uses the range-time... 

A 3-D Hough transform is introduced for detection of linear trajectories in a 3-D data space. Data space is constructed from returned radar data using range, bearing, and time information. This information is then mapped into a 3-D Cartesian data space. The constant velocity target trajectories appear as straight lines in this space, and are detected by the usage of 3-D Hough transform. The efficacy of the 3-D Hough transform is verified by simulation. In comparison with the 2-D case, when only the range-time information is used, the 3-D Hough transform has a better performance. © 2008 IEEE  

NiTiHf thin films with varying hafnium contents up to 28.7at% were fabricated using simultaneous sputter deposition from separate Ni, Ti, and Hf targets onto unheated substrates. The required film composition was achieved by adjusting the power ratio to the targets. The as-deposited films were amorphous; and post deposition annealing was performed at 550°C, slightly above their crystallization temperatures. The crystallization temperature of the films varied as a function of Hf concentration, and was as high as 520°C at a Hf content of 28.7at%. 2μm thick crystallized films with I0at% or greater Hf were martensitic at room temperature. DSC analysis demonstrated that above 10at%Hf additions... 

Multiple target detection in conventional PCL (Passive Coherent Location) radar systems by means of Ambiguity Function Processing and without any powerful algorithm is impossible. Presented Gradual Clean Algorithm (GCA) is a new and simple method, which could provide the perfect detection in noisy environment and heavy clutter condition up to SNR=-15 dB and SCR=-100 dB (clutter is assumed as a distributed target with large RCS). Determining the number of real targets and keeping the false alarm probability approximately constant are the presented algorithm capabilities  

Visual target tracking is one of the most sought-after yet challenging research topics in computer vision. Given the ill-posed nature of the problem and its popularity in a broad range of real-world scenarios, a number of large-scale benchmark datasets have been established, on which considerable methods have been developed and demonstrated with significant progress in recent years - predominantly by recent deep learning (DL)-based methods. This survey aims to systematically investigate the current DL-based visual tracking methods, benchmark datasets, and evaluation metrics. It also extensively evaluates and analyzes the leading visual tracking methods. First, the fundamental... 

In this paper, a novel scheme of command to line-of-sight guidance law regarding the outstanding practical limitations is proposed. With the aid of formulating problem in pursuer's line of sight frame, the exact feed-forward acceleration commands are derived for a general target motion in three-dimensional engagement geometry. Then, a nonlinear control scheme constructed from feed-forward terms along with a nested saturated feedback strategy is suggested. Two momentous practical limitations are considered. The first is related to existence of pursuer's acceleration saturation which is ignored in all existing solutions. The required conditions to insure the global stability are derived... 

Visual target tracking is one of the most sought-after yet challenging research topics in computer vision. Given the ill-posed nature of the problem and its popularity in a broad range of real-world scenarios, a number of large-scale benchmark datasets have been established, on which considerable methods have been developed and demonstrated with significant progress in recent years - predominantly by recent deep learning (DL)-based methods. This survey aims to systematically investigate the current DL-based visual tracking methods, benchmark datasets, and evaluation metrics. It also extensively evaluates and analyzes the leading visual tracking methods. First, the fundamental... 

The control of a brachiation robot has been the primary objective of this study. A brachiating robot is a type of a mobile arm that is capable of moving from branch to branch similar to a long-armed ape. In this paper, to minimize the actuator work, Pontryagin's minimum principle was used to obtain the optimal trajectories for two different problems. The first problem considers “brachiation between fixed branches with different distance and height,” whereas the second problem deals with the “brachiating and catching of a moving target branch”. Theoretical results show that the control effort in the proposed method is reduced by 25% in comparison with the “target dynamics” method which was...