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Iranian Conference on Electrical Engineering (ICEE)

作者： Mohammad Dehghani S. Ali A. Moosavian Center of Excellence in Robotics and Control Tehran Iran

This paper presents a new modeling approach for continuum robotic arms. A lot of efforts have been done on modeling statics and dynamics of continuum robots, and two main methods have been developed. One is suitable for static modeling, in in-plane loadings, where the sections of a robot experiences constant moments along their length. The other method is the Theory of Cosserat rod, which gives a set of differential equations for statics and dynamics of slender flexible rods. While this method provide suitable models for statics of continuum robots, its dynamic models are not practical, in the sense of numerical calculations. The modeling approach proposed in this paper is based on dividing the robot into many circular elements. Using this approach, modeling of the statics of continuum robots will be presented. Then, the proposed model will be validated using experimental data, to show the precision of the model. Finally, the merit and potentials of this method will be discussed, in conclusion.

关键词： Robots Mathematical model Equations Numerical models Kinematics Load modeling Force

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A new approach for orientation determination

A new approach for orientation determination

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2013 1st RSI/ISM International Conference on robotics and Mechatronics, ICRoM 2013

作者： Dehghani, Mohammad Moosavian, S. Ali A. Center of Excellence in Robotics and Control Dept. of Mechanical Eng. K. N. Toosi Univ. of Tech. Tehran Iran

ISBN: (纸本)9781467358118

In some modeling and control problems, especially in robotics, determination of orientation of a rotating body or frame requires slow and time taking numerical calculations. In some cases, such as for continuum robots, these time-taking calculations are an impediment to real-time control. The common approaches for orientation determination, such as Euler angles or Euler parameters, are beneficial when generalized coordinates are needed. Otherwise, these approaches require some time-taking equations for calculation of the rotation matrix (direction cosine matrix). Another method is to calculate the rotation matrix directly, based on the angular velocity. Although this method is very fast, it is numerically unstable, because of accumulation of some numerical errors. In this paper, an approach is introduced that cancels these errors with the least numerical efforts, and provides high accuracies. The application and importance of this approach is studied and discussed in the case of modeling and control of continuum robotic arms, as an instance. The proposed methods are used to model a spring, as a case study. The obtained results are validated by analytic data, and are compared to the results obtained by other methods. © 2013 IEEE.

关键词： Real time control

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Modeling of continuum robots with twisted tendon actuation systems

Modeling of continuum robots with twisted tendon actuation s...

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2013 1st RSI/ISM International Conference on robotics and Mechatronics, ICRoM 2013

作者： Dehghani, Mohammad Moosavian, S. Ali A. Center of Excellence in Robotics and Control Dept. of Mechanical Eng. K. N. Toosi Univ. of Tech. Tehran Iran

ISBN: (纸本)9781467358118

In contrast to traditional articulated robots, continuum robots do not have any joints. The backbone of these robots can be bent, twisted and stretched by environmental and actuation forces. A group of continuum robotic arms use tendon-driven actuation systems. In this group, the shape of robot backbone can be controlled by pulling the tendons. Generally, exact modeling of the forces and moments produced by tendon-driven systems has no closed form solution. However, for a simplified case where the backbone shape is a planar curve with a constant curvature, some closed-form solutions have been introduced. Such solutions are valuable, especially in control applications where Jacobian matrices must be calculated. For exact modeling of elastic rods in spatial deformations, constant curvature models are not accurate. In such cases, the theory of Cosserat rod can be used for backbone modeling. Continuum robots usually consist of an elastic rod as the backbone and an actuation system. The effects of the actuation systems must be included to the model of Cosserat rod. The effects of the actuation systems are more complicated, when the tendon passages are not parallel to the backbone. In this paper, a model for continuum robotic arms is presented, which considers both, the elastic backbone and the effects of the actuation system. Furthermore, the tendons can twist around the backbone, in an arbitrary passage. The presented model is more compact than other solutions, and will be validated in a case study, by comparison with numerical results obtained from existing models. © 2013 IEEE.

关键词： Tendons

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Context transfer and Q-Transferable tasks 29

Context transfer and Q-Transferable tasks

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29th AAAI Conference on Artificial Intelligence, AAAI 2015

作者： Mousavi, Amin Araabi, Babak Nadjar Ahmadabadi, Majid Nili Robotics and AI Lab Control and Intelligent Processing Center of Excellence School of Electrical and Computer Engineering University of Tehran Iran School of Cognitive Science Tehran Iran

ISBN: (纸本)9781577357209

This article discusses the notion of context transfer in reinforcement learning tasks. Context transfer, as defined in this article, implies knowledge transfer between tasks that share the same environment's dynamics and reward function, but have different state and action spaces. For example, we have a working mobile robot in an environment. At some point, we decide to upgrade its sensors and/or actuators. Any change in these modules will result in a different description of the agent- environment model, and the trained knowledge is no longer applicable. We consider the tasks of the old and new robots, as the source and target tasks, respectively. The Markov decision process (MDP) of these tasks, under certain conditions, are called Q-transferable tasks, and the problem of knowledge transfer between them is called context transfer. We investigate the relation of the MDPs of these tasks. Copyright © 2015, Association for the Advancement of Artificial Intelligence (***). All rights reserved.

关键词： Markov processes

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Characteristics identification of continuum robots for exact modeling

Characteristics identification of continuum robots for exact...

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2013 1st RSI/ISM International Conference on robotics and Mechatronics, ICRoM 2013

作者： Dehghani, Mohammad Moosavian, S. Ali A. Center of Excellence in Robotics and Control Dept. of Mechanical Eng. K. N. Toosi Univ. of Tech. Tehran Iran

ISBN: (纸本)9781467358118

Continuum robots do not have any joint in contrast to traditional articulated robots. Instead, these robots can bend, twist and stretch their backbone, to shape desired configurations and end-effector position. Therefore, exact modeling of these robots is a challenging problem, particularly in spatial deformations. This paper suggests identification of some mechanical characteristics of the backbone of continuum robots, to achieve accurate results. The importance of identification of characteristics, such as undeformed shape and modulus of elasticity, will be discussed. Then, some methods to identify these characteristics are presented. Theory of Cosserat Rod will be introduced and used for modeling continuum robotic arms in this paper. Finally, the proposed approach is used for a given robot, and the model obtained based on the identified parameters will be validated by experimental results. © 2013 IEEE.

关键词： End effectors

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A new approach in gait planning for humanoid robots

A new approach in gait planning for humanoid robots

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2013 1st RSI/ISM International Conference on robotics and Mechatronics, ICRoM 2013

作者： Khadiv, Majid Moosavian, S. Ali A. Center of Excellence in Robotics and Control Department of Mechanical Engineering K. N. Toosi Univ. of Technology PO Box 19395-1999 Tehran Iran

ISBN: (纸本)9781467358118

Due to redundancy and natural instability of humanoid robots, their motion planning becomes a challenging task. Designing stable gaits with smooth trajectories for a humanoid robot is the main goal of this article. Taking all related parameters on robot's walking into consideration, a new gait planning approach in the task space is developed. Various aspects like upper-body motion and stability requirements have the most significant role in this new gait planning process. In order to reduce undesired fluctuations on robot center of mass a new method in trajectory planning is also suggested. To show performance of the proposed algorithm, it is compared with another reliable approach in this field, and the results will be discussed. © 2013 IEEE.

关键词： Inverse kinematics

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Dynamics modelling and stable motion control of a Ballbot equipped with a manipulator

Dynamics modelling and stable motion control of a Ballbot eq...

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2013 1st RSI/ISM International Conference on robotics and Mechatronics, ICRoM 2013

作者： Asgari, Pouya Zarafshan, Payam Moosavian, S. Ali A. Center of Excellence in Robotics and Control Department of Mechanical Engineering K. N. Toosi Univ. of Technology PO Box 19395-1999 Tehran Iran

ISBN: (纸本)9781467358118

Human-Robot physical interaction is an important attribute for robots operating in human environments. A Ballbot is an under-actuated system with nonholonomic dynamic constraints. It is a skinny robot with a small base that helps the robot to move in limited space. It is as tall as human height until could interact by people whereas a Ballbot has not been equipped with a manipulator. This manipulator adds new advantages to the Ballbot such as object manipulation and grasping. In this paper and to achieve more performance of a Ballbot, it is equipped with a PUMA type manipulator which gives to the proposed robot the capability of better stabilization. To this end, dynamics equations of the assumed mobile robot is presented and verified. Then, by respecting to this fact that a Ballbot is in the class of under-actuated systems, a control algorithm is proposed to attain the stable motion control of the system. Finally, a simulation routine is performed to move along the desired path/trajectory. Obtained results reveal the merits of the verified model of the new Ballbot and the considered control algorithm which will be discussed. © 2013 IEEE.

关键词： Manipulators

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A stable nonlinear in parameter neural network controller for a class of saturated nonlinear systems 19

A stable nonlinear in parameter neural network controller fo...

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19th IFAC World Congress on International Federation of Automatic control, IFAC 2014

作者： Esfandiari, K. Abdollahi, F. Talebi, H.A. Center of Excellence on Control and Robotics Department of Electrical Engineering AmirKabir University of Technology Tehran Iran Department of Electrical and Computer Engineering Concordia University MontrealQC Canada

ISBN: (纸本)9783902823625

This paper deals with the tracking problem for a class of uncertain nonlinear systems subjected to actuator saturation constraint. Despite most of proposed control schemes for saturated systems which employed linear in parameter neural networks (LPNNs), in the present work nonlinear in parameter neural network (NLPNN) is introduced to support global approximation property. To compensate the effect of the input saturation constraint an auxiliary system is introduced and the error dynamics are modified based on the auxiliary states. Then, learning rules are achieved based on the back propagation (BP) algorithm and by adding two robustifying terms to the standard BP learning rules the stability of the overall system is ensured via Lyapunov direct method. Finally simulations performed on a "generalized pendulum" nonlinear system to illustrate the effectiveness of the proposed tracking control scheme. © IFAC.

关键词： Adaptive control systems

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Pursuit formation control scheme for double-integrator multi-agent systems 19

Pursuit formation control scheme for double-integrator multi...

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19th IFAC World Congress on International Federation of Automatic control, IFAC 2014

作者： Rezaee, Hamed Abdollahi, Farzaneh Center of Excellence on Control and Robotics Department of Electrical Engineering AmirKabir University of Technology Tehran Iran Department of Electrical and Computer Engineering Concordia University MontrealQC Canada

ISBN: (纸本)9783902823625

Pursuit formation control of double-integrator Multi-Agent Systems (MASs) is considered in this paper. To achieve a formation, a hierarchical control scheme is proposed in two layers. In the first layer, in a leaderless architecture, each agent pursues another one in a cyclic topology to achieve a regular polygon formation around a centroid, namely, pursuit centroid, and in the second layer, the agents agree on a pursuit centroid around which they pursue each other. Despite existing cyclic pursuit approaches in the literature which are based on agents with kinematic models and constant forward speeds, the proposed approach is based on agents with double-integrator dynamics without speed constraints. Numerical simulations for a team of six agents confirm the accuracy of the proposed control scheme. © IFAC.

关键词： Multi agent systems

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The effect of finite duration inputs on the dynamics of a system： Proposing a new approach for cancer treatment

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International Journal of Biomathematics 2015年第3期8卷 155-173页

作者： Mostafa Nazari Ali Ghaffari Center of Excellence in Robotics and Control K. N. Toosi University of Technology Pardis St. Tehran 19697 64499 Iran Mechanical Engineering DepartmentK. N. Toosi University of TechnologyPardis St. Tehran 19697 64499 Iran

In this paper, a principal question regarding the effect of inputs on the characteristics of dynamic systems is discussed. Whether an input implemented only for a limited duration, can change the characteristics of a dynamic system such that the behavior of the free system, after eliminating the input, differs from that before acting the input？ In this paper, it is shown that a limited time acted input is not able to change the dynamical properties of a system after its elimination. Regarding the proposed approach, a novel finite duration treatment method is developed for a tumor-immune system. The vaccine therapy is used to change the parameters of the system and the chemotherapy is applied for pushing the system to the domain of attraction of the healthy state. For optimal chemotherapy, an optimal control is used based on state-dependent Riccati equation （SDRE）. It is shown that, in spite of eliminating the treatment （therapeutic inputs）, the system approaches to healthy state conditions. The present analysis suggests that a proper treatment method must change the dynamics of the cancer instead of only reducing the population of cancer cells.

关键词： Cancer stability changeable dynamic properties system.

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