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#### Solving robot motion planning problem using Hopfield neural network in a fuzzified environment

, Article IEEE International Conference on Plasma Science ; Volume 2 , 2002 , Pages 1144-1149 ; 07309244 (ISSN) ; Taheri, J ; Sharif University of Technology
2002

Abstract

In this paper, a new approach based on Artificial Neural Networks to solve the robot motion planning problem is presented. For this purpose, a Hopfield Neural Network is used in a certain constraint satisfaction problem of the robot motion planning in conjunction with fuzzy modeling of the real robot's environment so that the energy of a state can be interpreted as the extent to which a hypothesis fit the underlying neural formulation model. Thus, low energy values indicate a good level of constraint satisfaction of the problem. Finally, since the obtained answer by the Hopfield Neural Network is not optimal, some algorithms are designed to optimize and generate the final answer

#### Real-Time Hybrid Motion Planning For Autonomous Uavs in Dynamic Environments

, M.Sc. Thesis Sharif University of Technology ; Alasty, Aria (Supervisor)
Abstract

This study is about real-time hybrid motion planning for autonomous UAVs in dynamic environments. The algorithm is based on system dynamic quantization to trim trajectories and maneuvers, constructing a library of primitives which guarantee the controllability of the system. Random algorithms introduced in literature of motion planning have an offline phase, reducing the computational complexity of online phase. By using dynamic quantization, we have achieved a new totally online algorithm, increasing the probability of finding a solution. Dynamic programming is the core of this algorithm, instead of offline calculations in before random algorithms. In order to decrease the exponential...

#### A voronoi-based reactive approach for mobile robot navigation

, Article 13th International Computer Society of Iran Computer Conference on Advances in Computer Science and Engineering, CSICC 2008, Kish Island, 9 March 2008 through 11 March 2008 ; Volume 6 CCIS , 2008 , Pages 901-904 ; 18650929 (ISSN); 3540899847 (ISBN); 9783540899846 (ISBN) ; Hazar, N ; Sharif University of Technology
2008

Abstract

Robot navigation is a challenging problem in robotics, which involves determining of robot positioning relative to objects in the environment, and also the mobility of robot through obstacles without colliding into them. The former is known as localization, while the latter is called motion planning. This paper introduces a roadmap method for solving motion planning problem in a dynamic environment based on Generalized Voronoi Diagram (GVD). The efficiency of the proceeding work is verified by examining it in a sample home environment. © 2008 Springer-Verlag

#### An approximation algorithm for d1-optimal motion of a rod robot with fixed rotations

, Article International Journal of Computer Mathematics ; Volume 83, Issue 3 , 2006 , Pages 357-370 ; 00207160 (ISSN) ; Ghodsi, M ; Sharif University of Technology
2006

Abstract

Given a translating and rotating rod robot in a plane in the presence of polygonal obstacles with the initial and final placements of the rod known, the d1-optimal motion planning problem is defined as finding a collision-free motion of the rod such that the orbit length of a fixed but arbitrary point F on the rod is minimized. In this paper we study a special case of this problem in which the rod can translate freely, but can only rotate by some pre-specified given angles around F. We first characterize the d1-optimal motion of the robot under the given conditions and then present a (1 + ε)-approximation algorithm for finding the optimal path. The running time of the algorithm is bounded by...

#### A Motion Planning System in an Unknown Environment

, M.Sc. Thesis Sharif University of Technology ; Vosoughi Vahdat, Bijan (Supervisor) ; Mortazavi, Mohammad (Supervisor)
Abstract

Science has been improved in all aspects and robotics is considered an important field, which helps, do work more efficiently. In the meantime, one of the most popular aspects of robotics is the movement, both physical (in terms of the number of mechanical actuators, the number of arms and legs, the number of wheels, the robot's weight and gravity) and in terms of programming and algorithms. Programming and algorithms are divided into two categories: 1. Programs to control robots and manipulate dynamics associated with robot movement. 2. Algorithms and the ways for routing. The first group is programming associated with control of robots. Motion planning or path planning is the next. In...

#### Optimization of kinematic redundancy and workspace analysis of a dual-arm cam-lock robot

, Article Robotica ; 2014 ; ISSN: 02635747 ; Osgouie, K. G ; Meghdari, A ; Sharif University of Technology
Abstract

In this paper, the problem of obtaining the optimal trajectory of a Dual-Arm Cam-Lock (DACL) robot is addressed. The DACL robot is a reconfigurable manipulator consisting of two cooperative arms, which may act separately. These may also be cam-locked in each other in some links and thus lose some degrees of freedom while gaining higher structural stiffness. This will also decrease their workspace volume. It is aimed to obtain the optimal configuration of the robot and the optimal joint trajectories to minimize the consumed energy for following a specific task space path. The Pontryagin's Minimum Principle is utilized with a shooting method to resolve kinematic redundancy. Numerical examples...

#### Investigating dynamic interaction between the one D.O.F. Manipulator and vehicle of a mobile manipulator

, Article Journal of Intelligent and Robotic Systems: Theory and Applications ; Volume 28, Issue 3 , 2000 , Pages 277-290 ; 09210296 (ISSN) ; Durali, M ; Naderi, D ; Sharif University of Technology
2000

Abstract

A manipulator mounted on a moving vehicle is called a mobile manipulator. A mobile manipulator with an appropriate suspension system can pass over uneven surfaces, thus having an infinite workspace. If the manipulator could operate while the vehicle is traveling, the efficiency concerning with the time and energy used for stopping and starting will be increased. This paper presents the kinematic and dynamic modeling of a one degree of freedom manipulator attached to a vehicle with a two degrees of freedom suspension system. The vehicle is considered to move with a constant linear speed over an uneven surface while the end effector tracks a desired trajectory in a fixed reference frame. In...

#### Extensions to Feedback Motion Planning

, M.Sc. Thesis Sharif University of Technology ; Ghodsi, Mohammad (Supervisor) ; Abam, Mohammad Ali (Co-Advisor)
Abstract

One of the ultimate goals in robotics is to design autonomous robots. Among other things, this means a robot has to be able to plan its own motion. To be able to plan a motion, a robot must have some knowledge about the environment in which it is moving. Some of this information can be provided by a floor plan. For other information the robot will have to rely on its sensors. In this thesis, we consider that the environment is unknown for the robot. So, the robot uses weak sensor to planning its motion. The sensor can distinguish between colors. The robot can follow the colors. Therefore, we need to specify the umber of colors in which the robot can navigate by them. We propose an efficient...

#### Optimal maneuver-based motion planning over terrain and threats using a dynamic hybrid PSO algorithm

, Article Aerospace Science and Technology ; Volume 26, Issue 1 , April–May , 2013 , Pages 60-71 ; 12709638 (ISSN) ; Pourtakdoust, S. H ; Sharif University of Technology
2013

Abstract

Motion planning is a key factor in enhancing the autonomy level of unmanned flying vehicles. A new dynamic hybrid algorithm is developed to solve the motion planning problem in real-time using a heuristic optimization approach. The proposed algorithm effectively combines desired features such as rapid convergence to an optimal path with reduced computational effort. In addition to the terrain obstacles, the proposed algorithm is able to avoid random threats that may arise sporadically in the terrain. Using the maneuver automaton concept, nonlinear dynamic model and performance constraints are also considered in the process of motion planning to further ensure feasible trajectories....

#### Adaptive motion planning with artificial potential fields using a prior path

, Article International Conference on Robotics and Mechatronics, ICROM 2015, 7 October 2015 through 9 October 2015 ; 2015 , Pages 731-736 ; 9781467372343 (ISBN) ; Jamzad, M ; Sharif University of Technology
2015

Abstract

Motion planning in an autonomous agent is responsible for providing smooth, safe and efficient navigation. Many solutions for dealing this problem have been offered, one of which is, Artificial Potential Fields (APF). APF is a simple and computationally low cost method which keeps the robot away from the obstacles in environment. However, this approach suffers from trapping in local minima of potential function and then fails to produce motion plans. Furthermore, Oscillation in presence of obstacles or in narrow passages is another disadvantage of the method which makes it unqualified for many planning problems. In this paper we aim to resolve these deficiencies by a novel approach which...

#### A real-time algorithm for variable-objective motion planning over terrain and threats

, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 229, Issue 6 , 2015 , Pages 1043-1056 ; 09544100 (ISSN) ; Pourtakdoust, S. H ; Sharif University of Technology
SAGE Publications Ltd
2015

Abstract

A major issue required to enhance the autonomy level of unmanned vehicles is real-time motion planning. In this context, optimal trajectories need to be generated online considering the vehicle's dynamic potentials and constraints. However, autonomous air vehicles often need to plan and execute their missions with varying objectives that may even be dictated in flight. Therefore, the current study introduces and focuses on the new concept of variable-objective motion planning. In this regard, a new dynamic multi-objective heuristic optimization algorithm is developed for path and motion planning of autonomous air vehicles in presence of deterministic terrain obstacles as well as random...

#### Clearing an orthogonal polygon to find the evaders

, Article Theoretical Computer Science ; Volume 847 , December , 2020 , Pages 175-184 ; Ghodsi, M ; Sharif University of Technology
Elsevier B. V
2020

Abstract

In a multi-robot system, a number of autonomous robots would sense, communicate, and decide to move within a given domain to achieve a common goal. In the pursuit-evasion problem, a polygonal region is given and a robot called a pursuer tries to find some mobile targets called evaders. The goal of this problem is to design a motion strategy for the pursuer such that it can detect all the evaders. In this paper, we consider a new variant of the pursuit-evasion problem in which the robots (pursuers) each moves back and forth along an orthogonal line segment inside a simple orthogonal polygon P. We assume that P includes unpredictable, moving evaders that have bounded speed. We propose the...

#### A deadlock free shortest path routing algorithm for WK-recursive meshes

, Article 9th International Conference on Distributed Computing and Networking, ICDCN 2008, Kolkata, 5 January 2008 through 8 January 2008 ; Volume 4904 LNCS , 2008 , Pages 280-285 ; 03029743 (ISSN); 3540774432 (ISBN); 9783540774433 (ISBN) ; Hoseiny Farahabady, M ; Sarbazi Azad, H ; Sharif University of Technology
Springer Verlag
2008

Abstract

In this paper, we investigate an efficient deadlock-free shortest path routing algorithm for WK-recursive mesh networks which has been shown that possess several advantages like suitable to be manufactured by VLSI technology and easy to be expanded. It will be shown that the proposed algorithm requires O(√n) routing steps (where N is the network size) to route the entire network by exploiting either the self-routing or second order routing scheme. © Springer-Verlag Berlin Heidelberg 2008

#### An effective manipulator trajectory planning with obstacles using virtual potential field method

, Article 2007 IEEE International Conference on Systems, Man, and Cybernetics, SMC 2007, Montreal, QC, 7 October 2007 through 10 October 2007 ; January , 2007 , Pages 1573-1578 ; 1062922X (ISSN); 1424409918 (ISBN); 9781424409914 (ISBN) ; Sharif University of Technology
2007

Abstract

This paper presents a new approach for trajectory planning of manipulator robots based on Virtual Potential Field (VPF) in presence of static obstacles. In this method, a series of via points between starting point and goal point is obtained by traverse end-effector of manipulator in affected by different VPF while avoiding obstacles in the Cartesian space. An optimum trajectory is generated by using pattern search algorithm which determines strength of potential fields to minimize the value of desired objective function. Cubic splines are used to generate a smooth trajectory through path points in joint space that are obtained by inverse kinematics solution of corresponding points in the...

#### Novel minimum time trajectory planning in terrain following flights

, Article IEEE Transactions on Aerospace and Electronic Systems ; Volume 43, Issue 1 , 2007 , Pages 2-12 ; 00189251 (ISSN) ; Kosari, A. R ; Sharif University of Technology
2007

Abstract

A new methodology has been proposed to enhance inverse dynamics applications in the process of trajectory planning and optimization in terrain following flights (TFFs). The new approach uses a least square scheme to solve a general two-dimensional (2-D) TFF in a vertical plane. In the mathematical process, Chebyshev polynomials are used to model the geographical data of the terrain in a given route in a manner suitable for the aircraft at hand. The aircraft then follows the modeled terrain with sufficient clearance. In this approach the terrain following (TF) problem is effectively converted to an optimal tracking problem. Results show that this method provides a flexible approach to solve...

#### Mechanism synthesis for path generation using the curvature based - Deflection based objective function

, Article WSEAS Transactions on Systems ; Volume 5, Issue 12 , 2006 , Pages 2839-2843 ; 11092777 (ISSN) ; Jafarijashemi, G ; Mamduhi, M ; Aghmioni, A. N ; Zohoor, H ; Sharif University of Technology
2006

Abstract

This paper proposed a new curvature based path-description method for path-generation of planar mechanism, in which the position vector of a point on coupler, which follows most closely a predefined path, is directly calculated as a function of coupler motion properties. In addition this curvature based method makes it possible to define an objective function independent of rotation and translation transformations. Therefore, in this method, initial position, orientation, and coupler point vector parameters are not the optimization variable. These five parameters could be calculated as a function of other design parameters and they are found when these optimal values are obtained. Reducing...

#### Integrated motion planning and trajectory control system for unmanned air vehicles

, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 227, Issue 1 , 2013 , Pages 3-18 ; 09544100 (ISSN) ; Pourtakdoust, S. H ; Sharif University of Technology
2013

Abstract

Motion planning and trajectory control are two basic challenges of unmanned vehicles. In motion planning problem, feasible trajectories are developed while nonlinear dynamic model and performance constraints of the vehicle under utility are considered. In this study, motion planning is performed via an enhanced particle swarm optimization algorithm. The resulting offline generated trajectories are tracked using a nonlinear trajectory control system methodology. The Lyapunov-based constrained backstepping approach and command filters are utilized in designing the trajectory control system. Command filters smoothen the input signals and provide their derivatives. Evaluation of the proposed...

#### A new motion planning method for discretely actuated hyper-redundant manipulators

, Article Robotica ; February , 2015 ; 02635747 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Cambridge University Press
2015

Abstract

A hyper-redundant manipulator is made by mounting the serial and/or parallel mechanisms on top of each other as modules. In discrete actuation, the actuation amounts are a limited number of certain values. It is not feasible to solve the kinematic analysis problems of discretely actuated hyper-redundant manipulators (DAHMs) by using the common methods, which are used for continuous actuated manipulators. In this paper, a new method is proposed to solve the trajectory tracking problem in a static prescribed obstacle field. To date, this problem has not been considered in the literature. The removing first collision (RFC) method, which is originally proposed for solving the inverse kinematic...

#### A new motion planning method for discretely actuated hyper-redundant manipulators

, Article Robotica ; Volume 35, Issue 1 , 2017 , Pages 101-118 ; 02635747 (ISSN) ; Zohoor, H ; Habibnejad Korayem, M ; Sharif University of Technology
Cambridge University Press
2017

Abstract

A hyper-redundant manipulator is made by mounting the serial and/or parallel mechanisms on top of each other as modules. In discrete actuation, the actuation amounts are a limited number of certain values. It is not feasible to solve the kinematic analysis problems of discretely actuated hyper-redundant manipulators (DAHMs) by using the common methods, which are used for continuous actuated manipulators. In this paper, a new method is proposed to solve the trajectory tracking problem in a static prescribed obstacle field. To date, this problem has not been considered in the literature. The removing first collision (RFC) method, which is originally proposed for solving the inverse kinematic...

#### A new online random particles optimization algorithm for mobile robot path planning in dynamic environments

, Article Mathematical Problems in Engineering ; Volume 2013 , 2013 ; 1024123X (ISSN) ; Kiani, K ; Samiei, E ; Sharifi, M ; Sharif University of Technology
2013

Abstract

A new algorithm named random particle optimization algorithm (RPOA) for local path planning problem of mobile robots in dynamic and unknown environments is proposed. The new algorithm inspired from bacterial foraging technique is based on particles which are randomly distributed around a robot. These particles search the optimal path toward the target position while avoiding the moving obstacles by getting help from the robot's sensors. The criterion of optimal path selection relies on the particles distance to target and Gaussian cost function assign to detected obstacles. Then, a high level decision making strategy will decide to select best mobile robot path among the proceeded particles,...