Journal of Computer and Robotics
Volume:10 Issue: 2, Summer and Autumn 2017

In this paper, a novel adaptive sliding mode control for rigid robot manipulators is proposed. In the proposed system, since there may exist explicit unknown parameters and perturbations, a Lyapunov based approach is presented to increase system robustness, even in presence of arbitrarily large (but not infinite) discontinuous perturbations. To control and track the robot, a continuous controller is designed with two phases of adaptation. The first phase is related to the robot parameters and the other one is accounted for perturbation estimating. We investigated the stability in the sense of Lyapunov with derive adaptive laws and uniform ultimate boundedness in the applied worst condition. The simulation results for two degrees of freedom rigid robot manipulator effectively demonstrate capability of the mentioned approach. Moreover, the results show that the domain of attraction is so vast and a global uniform ultimate boundedness could be expected.

One of the main problems of car-like robot is robust path following in the presence of sliding effect. To tackle this problem, a robust mix H2/H∞ static state feedback control method is selected. This method is the well-known linear robust controller which is robust against external disturbance as well as model uncertainty. In this paper, the path following problem is formulated as linear matrix inequality for the kinematic model of car-like robot, which includes sliding effect. The robustness and path following performance of the proposed controller are investigated based on the comparison of suggested controller with an optimal proportional integral controller. The simulation results, which have been performed by MATLAB Simulink, shows the presented controller is able to follow various paths including simple, linear and more complex function path like square, and sine function path even in the presence of sliding effect. In addition, the robustness and correctness of closed-loop system in the simulations are demonstrated based on the nonlinear analysis of equilibrium point.

In this paper, a high frequency contactless power transfer (CPT) system is designed with ∅2 inverter drive. This system works in 30MHz frequency and 380W power with low voltage stress and considers the inductive link parasitic capacitor effect. In the design, we formulated the inverter equations first and then suggested another design for the transmitter and the receiver coils as the energy transfer medium. Following the inverter equations, structures of proper coil are designed for a CPT system. The results of the coil and ∅2 inverter designs are implemented as a bipolar circuit model which is equal to considering the inductive link parasitic capacitors. The system characteristics such as the stress, efficiency, mutual induction, field scattering, magnetic field distribution and the parameters’ variations are evaluated along with analysis. The results demonstrate that the presented CPT system has high efficiency, low switching voltage stress, small passive energy storage elements and fast dynamic response.

Wireless mesh networks (WMNs) which mediates the broadband Internet access, have been recently received many attentions by the researchers. In order to increase capacity in these networks, nodes are equipped with multiple radios tuned on multiple channels emerging multi radio multi-channel WMNs (MRMC WMNs). Therefore, a vital challenge that poses in MRMC WMNs is how to properly assign channels to the radios. On the other hand, multicast routing lets the delivery of data possibly from one source to several destinations which makes it suitable for multimedia applications such as video conferencing and distant learning. In this paper, different methods of multicast routing in WMNs are investigated. Moreover, the existing methods are classified from the viewpoints of management style (centralized / decentralized) and achieving optimal solution (heuristic / meta-heuristic / operation research).

One of the major cipher symmetric algorithms is AES. Its main feature is to use S-BOX step, which is the only non-linear part of this standard possessing fixed structure. During the previous studies, it was shown that AES standard security was increased by changing the design concepts of S-BOX and production of dynamic S-BOX. In this paper, a change of AES standard security is studied by production of dynamic and key-dependent S-BOX. Also the LFSR random number generation hardware algorithm is applied in order to produce the dynamic S-BOX. In order to produce a dynamic and key-dependent S-BOX, the field bits of key are divided into separated bits at first and then a byte is selected by LFSR algorithm randomly. The number of selected bit is considered as the repeating number of LFSR algorithm and is applied in order to produce dynamic S-BOX. In the evaluation step, we compared the proposed model with fixed S-BOX model in the original AES algorithm. It was shown that the proposed implementation could increase the security as about 0.2%, 0.017% and 0.19%, 0.04 in the case of avalanche effect, output bits dependence criteria, compared with the strict avalanche criteria and in the case of linear criteria, respectively.

The aim of this paper is to detect bank credit cards related frauds. The large amount of data and their similarity lead to a time consuming and low accurate separation of healthy and unhealthy samples behavior, by using traditional classifications. Therefore in this study, the Adaptive Neuro-Fuzzy Inference System (ANFIS) is used in order to reach a more efficient and accurate algorithm. By combining evolutionary algorithms with ANFIS, the optimal tuning of ANFIS parameters is achieved by the Teaching-Learning-Based Optimization (TLBO) and the Particle Swarm Optimization (PSO). The aim of using this approach is to improve the network performance and to reduce calculation complexities compared to gradient descent and least square methods. The proposed algorithm is implemented and evaluated on credit cards data to detect fraud. The results demonstrate superior performance of the designed scheme compared to other intelligent identification methods.

The emerging Internet of Things (IoT) connects the physical world to the digital one and composes large networks of smart devices to support various applications. In order to provide a suitable communication in such networks, a reliable routing protocol is needed. In this paper, a modified version of an IPv6 Routing Protocol for Low-Power and Lossy networks (RPL), which has been standardized by IETF is proposed. It is used in Low power and Lossy Networks (LLNs) that consist of lossy links and electronic devices use a set of novel Internet of Things technologies. RPL protocol is based on the constructional concept of Directed Acyclic Graphs (DAGs) that is constructed using a scalar value called rank. The default metric which is commonly used in low power and lossy networks to compute rank of Expected Transmission Count (ETX) based on the number of re-transmission. While the results represent that this method of calculation is not effective enough. Therefore, we introduce a new method of ETX computation which is used to construct the DAGs with better rank computation and selected routes. The simulation results show that our proposed idea has better performance in contrast with the basic RPL and AODV protocols in terms of Packet Delivery Ratio (PDR), number of re-transmission, end to end delay, and throughput.

Wheeled mobile manipulators utilize both the locomotion capabilities of the wheeled platform and manipulation capacity of the arm. While the modelling and control of such systems have previously been studied, most of them have considered robots with rigid suspension and their wheels are subject to pure rolling conditions. To relax the aforementioned limiting assumptions, this research addresses modelling and control of a mobile manipulator with flexible suspension while considers the frictional effects. To this end, the Newton-Euler approach is employed and the modelling process is elaborated. To control the system, a two degree-of-freedom policy is suggested at two levels. In the first level, the Multiple Impedance Control (MIC) algorithm is modified and then is effectively utilized. Next, in the second level, the wheels actuating torques are adjusted such that the required forces/torques of the platform resulted from the first level be realized. The obtained simulation results support the proficiency of the suggested control scenario to control of wheeled mobile robots with flexible suspension and pneumatic tires.