2018-08-21T18:43:24Z
http://ijr.kntu.ac.ir/?_action=export&rf=summon&issue=2125
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Visual Tracking using Kernel Projected Measurement and Log-Polar Transformation
Hamid
D. Taghirad
Hamid
D. Taghirad
Fateme
Bakhshande
Visual Servoing is generally contained of control and feature tracking. Study of previous methods shows that no attempt has been made to optimize these two parts together. In kernel based visual servoing method, the main objective is to combine and optimize these two parts together and to make an entire control loop. This main target is accomplished by using Lyapanov theory. A Lyapanov candidate function is formed based on kernel definition such that the Lyapanov stability can be verified. The implementation is done in four degrees of freedom and Fourier transform is used for decomposition of the rotation and scale directions from 2D translation. In the present study, a new method in scale and rotation correction is presented. Log-Polar Transform is used instead of Fourier transform for these two degrees of freedom. Tracking in four degrees of freedom is synthesized to show the visual tracking of an unmarked object. Comparison between Log-Polar transform and Fourier transform shows the advantages of the presented method. KBVS based on Log-Polar transform proposed in this paper, because of its robustness, speed and featureless properties.
Visual Servoing
Lyapanov Function
Log
Polar Transform
Fourier Transform
2015
06
01
1
12
http://ijr.kntu.ac.ir/article_12494_943887b9de23947c5793a6d4f7f0ed1b.pdf
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Optimization of the Kinematic Sensitivity and the Greatest Continuous Circle in the Constant-orientation Workspace of Planar Parallel Mechanisms
Mohammad
H. Saadatzi
Mehdi
Tale Masouleh
Morteza
Daneshmand
This paper presents the results of a comprehensive study on the efficiency of planar parallel mechanisms, considering their kinetostatic performance and also, their workspace. This aim is approached upon proceeding single- and multi-objective optimization procedures. Kinetostatic performances of ten different planar parallel mechanisms are analyzed by resorting to a recent index, kinematic sensitivity. Moreover, the greatest possible continuous circle in the constant-orientation workspace of the latter mechanisms is considered as another objective for the optimization procedures. Seeking the set of design parameters which compromises simultaneous optimal values for the two aforementioned objectives, i.e., kinematic sensitivity and workspace, necessitates launching a multi-objective optimization process. The mathematical framework adopted for the optimization problem is based on genetic algorithm. The results of multi-objective optimization are based on the sets of Pareto points, offering the most reliable decisions to reconciliate between some conïicting objectives. To this end, the ten planar parallel mechanisms are sorted into two sets based on their type of actuator, some of them with prismatic actuators and the other ones with revolute actuators. Finally, a comparison between performances of these mechanisms, according to the obtained results, is carried out.
Constant
orientation workspace
differential evolution
Kinematic sensitivity
NSGA
II
Planar parallel mechanisms
2015
06
01
12
21
http://ijr.kntu.ac.ir/article_12492_2fe566d0d187b3709b959ecde7d7c738.pdf
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Identification of an Autonomous Underwater Vehicle Dynamic Using Extended Kalman Filter with ARMA Noise Model
Saeed
Ebrahimi
Mohammad
Bozorg
Mehdi
Zare Ernani
In the procedure of designing an underwater vehicle or robot, its maneuverability and controllability must be simulated and tested, before the product is finalized for manufacturing. Since the hydrodynamic forces and moments highly affect the dynamic and maneuverability of the system, they must be estimated with a reasonable accuracy. In this study, hydrodynamic coefficients of an autonomous underwater vehicle (AUV) are identified using velocity and displacement measurements, and implementing an Extended Kalman Filter (EKF) estimator. The hydrodynamic coefficients are included in the augmented state vector of a six DOF nonlinear model. The accuracy and the speed of the convergence of the algorithm are improved by selecting a proper covariance matrix using the ARMA process model. This algorithm is used to estimate the hydrodynamic coefficients of two different sample AUVs: NPS AUV II and ISIMI. The comparison of the outputs of the identified models and the outputs of the real simulated models confirms the accuracy of the identification algorithm. This identification method can be used as an efficient tool for evaluating the hydrodynamic coefficients of underwater vehicles (robots), using the experimental data obtained from the test runs.
Autonomous Underwater Vehicle
Hydrodynamic coefficients
Extended Kalman Filter
system identification
parameter estimation
2015
06
01
22
28
http://ijr.kntu.ac.ir/article_12493_91150588423e7ecdc30a7575494e61a4.pdf
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Design and Kinematic Analysis of a 4-DOF Serial-Parallel Manipulator for a Driving Simulator
Mojtaba
Yazdani
Mohammadreza
Arbabtafti
Mehdi
Tale-Masouleh
Milad
Hasanvand
Ali
Nahvi
Amir
Jaberi
This paper presents the kinematic analysis and the development of a 4-degree-of-freedom serial-parallel mechanism for large commercial vehicle driving simulators. The degrees of freedom are selected according to the target maneuvers and the structure of human motion perception organs. Several kinematic properties of parallel part of the mechanism under study are investigated, including the inverse and the forward kinematics problems, workspace determination, singularity, and kinematic sensitivity analysis. The workspace of the parallel part of the mechanism is obtained by interval analysis. Moreover, using elimination theory, a univariate expression representing the forward kinematics solution of the parallel part is obtained.
driving simulator
Parallel mechanisms (PM)
Forward kinematics problem (FKP)
Kinematic sensitivity
Interval analysis
2015
06
01
29
37
http://ijr.kntu.ac.ir/article_12495_53d72b75fae2ad419b6fb69d2e8e59ed.pdf
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Control of Quadrotor Using Sliding Mode Disturbance Observer and Nonlinear Hâ
Kobra
Ghasemi
Ghasem
Alizadeh
In this paper, a nonlinear model of the underactuated six degrees of freedom (6 DOF) quadrotor helicopter was derived based on the Newton-Euler formalism. A new nonlinear robust control strategy was proposed to solve the stabilizing and path following problems in presence of external disturbances and parametric uncertainties. The proposed control structure consist of a sliding mode control based on disturbance observer (SMDO) to track the reference trajectory together with a nonlinear Hâ controller to stabilize the rotational movements. Simulation results in the presence of aerodynamic disturbances and parametric uncertainties are presented to corroborate the effectiveness and the robustness of the proposed strategy.
Disturbance Observer
Nonlinear H∞ Control
Sliding mode control
Quadrotor Helicopter
2015
06
01
38
46
http://ijr.kntu.ac.ir/article_12496_90601813885a23254cb41817db86767f.pdf
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Model Predictive Control and Stability Analysis of a Standing Biped with Toe-Joint
Mohammad Jafar
Sadigh
Mohammad Jafar
Sadigh
Ehsan
Kouchakia
In this paper standing balance control of a biped with toe-joint is presented. The model consists of an inverted pendulum as the upper body and the foot contains toe-joint. The biped is actuated by two torques at ankle-joint and toe-joint to regulate the upper body in upright position. To model the interaction between foot and the ground, configuration constraints are defined and utilized. To stabilize the biped around upright position, model predictive control (MPC) is implemented by which the constraints can be incorporate to the optimal control algorithm properly. To assess stability of system and to find domain of attraction of the fixed point, concept of Lyapunov exponents is utilized. Using the proposed control and stability analysis, we studied the effect of toe-joint in improving the stability of the biped and in decreasing actuator demand, necessary for stabilizing the system. In addition, effect of toe-joint is studied in improving domain of attraction of the stabilized fixed pint.
Model Predictive Control
Toe
Joint
Standing balance control
Lyapunov exponents
2015
06
01
47
54
http://ijr.kntu.ac.ir/article_12498_d23ca960080c146d85b660695b887d9e.pdf
International Journal of Robotics, Theory and Applications
IJR
2008-7144
2008-7144
2015
4
1
Conceptual Design of a Gait Rehabilitation Robot
Mohammad
D. Hasankola
Abbas
Ehsaniseresht
Majid
M. Moghaddam
Ali
Mirzaie Saba
Gait rehabilitation using body weight support on a treadmill is a recommended rehabilitation technique for neurological injuries, such as spinal cord injury. In this paper, a new robotic orthosis is presented for treadmill training. In the presented design the criteria such as low inertia of robot components, backdrivability, high safety and degrees of freedom based on human walking are considered. This robot is composed of a leg exoskeleton for leg control and a segment for pelvis control. In the exoskeleton two degrees of freedom are considered for the hip joint and one for the knee joint. Also two degrees of freedom are considered for the pelvis joints. The inertia of moving components and the required force for the robot motion are measured to evaluate the robot backdrivability and transparency. Further, a walking algorithm is implemented on the robot and is tested on a human subject. Evaluation of the design showed that the robot is suitable for gait rehabilitation exercises.
Rehabilitation
Treadmill Training
Exoskeleton Backdrivability
2015
06
01
55
61
http://ijr.kntu.ac.ir/article_12497_9637ea8724cc51fa6cd3242acc6f645b.pdf