فهرست مطالب

Robotics - Volume:5 Issue: 1, 2019
  • Volume:5 Issue: 1, 2019
  • تاریخ انتشار: 1398/04/19
  • تعداد عناوین: 6
  • Behnam Miripour Fard, Ahmad Bagheri *, Nader Nariman Zadeh Pages 1-15
    This paper presents the ability of hybrid zero dynamics (HZD) feedback control method to reproduce human like movements for walking push recovery of an under-actuated 3D biped model. The balance recovery controller is implemented on a three-dimensional under-actuated bipedal model subjected to a push disturbance. The biped robot model is considered as a hybrid system with eight degrees of freedom (DOF) in the single support phase and two degrees of under-actuation in the ankle joint. The control is done based on the method of virtual constraints and HZD, by adjusting the desired trajectory of the event-based feedback controller. Several simulations have been done considering pushes exerted during walking. The results showed the performance of the method in recovery of pushes occurring in the sagittal and frontal planes and also in the both directions, simultaneously. The results showed that the simulated motions can be characterized in terms of strategies observed in human for balance recovery against perturbations during walking.
    Keywords: Inverse biomimetic, Biped robot, 3D model, under-actuation, walking push recovery, hybrid feedback control
  • Seyyed Ali Mousavi Mohammadi, Alireza Akbarzadeh *, Ehsan Adel Rastkhiz, Morteza Shariatee Pages 16-26
    The present paper investigates an intuitive way of robot path planning, called robot teaching by demonstration. In this method, an operator holds the robot end-effector and moves it through a number of positions and orientations in order to teach it a desired task. The presented control architecture applies impedance control in such a way that the end-effector follows the operator’s hand with desired dynamic properties. The operator often teaches the robot in the middle of the robot workspace. Then, this leads to lose a lot of accessible space. Workspace boundary is specified where a joint meets its end or a singularity happens. In this paper, a method is proposed to warn the operator before the end-effector faces the boundary of the workspace which results in using the robot workspace efficiently. It is achieved by means of two fuzzy controllers which smoothly increase the damping parameter of the impedance controller when the robot is closing on to a joint limit or a singularity. The increase of damping parameter dissipates the kinetic energy that is imposed by the operator to move the end-effector toward workspace boundary. The proposed method is applied on an industrial grade SCARA type robot. Experimental results show the effectiveness of the proposed method in a clear way.
    Keywords: Physical human-robot interaction, Teaching by demonstration Impedance control, Fuzzy switching control
  • Alireza Khodayari *, Houri Khodayari, Farshad Pazooki Pages 27-34
    In this paper, an optimal stable algorithm is presented for members of a robots swarm moving toward a target. Equations of motion of the swarm are based on Lagrangian energy equations. Regarding of similar research On the design of swarm motion algorithm, an equation of motion considered constraints to guarantee no collision between the members and the members and obstacles along the motion path is presented. In order to optimize the swarm motion stability algorithm, the required constraints are introduced into the equations of motion in the form of a potential function. Considering Points of various coordinates on a target and applied potential function, each member is guided to the closest point using their coordinates while communicating with others from the beginning of the swarm motion. As a result, the need for having the members gathered within an area close to the center of the swarm observed in previously designed algorithms is eliminated. The designed optimal stability algorithm is simulated in MATLAB Software for a swarm composed of two robots under different sets of conditions. Simulation results of swarm member behavior were indicative of reducing mission time with increasing motion space for the swarm members while optimizing the behavior of the swarm moving toward the target. Finally, some experimental results related to designed algorithm are presented.
    Keywords: Swarm, Robot Swarm, Optimal Stability Algorithm, Simulation
  • Mohammad Bozorg *, Masoud Bahraini, Ahmad Rad Pages 35-46
    SLAM (Simultaneous Localization and Mapping) is a fundamental problem when an autonomous mobile robot explores an unknown environment by constructing/updating the environment map and localizing itself in this built map. The all-important problem of SLAM is revisited in this paper and a solution based on Adaptive Unscented Kalman Filter (AUKF) is presented. We will explain the detailed algorithm and demonstrate that the estimation error is significantly reduced and the accuracy of thenavigation is improved. A comparison among AUKF, Unscented Kalman Filter (UKF) and Extended Kalman Filter (EKF) algorithms is investigated through simulated as well as experimental dataset. An indoor dataset is generated from a two-wheel differential mobile robot in order to validate the robustness of AUKF-SLAM to noise of modeling and observation, and to examine the applicability of the method for real-time navigation. Both experimental and simulation results illustrate that AUKF-SLAM is more accurate than the standard UKF-SLAM and the EKF-SLAM. Finally, the well-known Victoria Park dataset is used to prove the applicability of the AUKF algorithm in large-scale environments.
    Keywords: SLAM, Adaptive UKF, Scaling Parameter, Mobile robots
  • Foudil Abdessemed * Pages 47-62
    This paper, proposes a methodology to implement a suitable nonsingular terminal sliding mode controller associated with the output feedback control to achieve a successful trajectory tracking of a non-holonomic wheeled mobile robot in presence of longitudinal and lateral slip accompanied. This implementation offers a relatively faster and high precision tracking performance. We investigate this approach and demonstrate its feasibility for such situations where robustness against perturbation and measurement errors are required. In this study, tyre-forces are considered as perturbation. These forces appear because of wheel slip of the wheeled mobile robot moving at high speed or on a slippery surface. The need to compensate these forces are achieved through a design of an intelligent estimation paradigm. The estimator is realized by a fuzzy logic model that requires slip angle and slip ratio as inputs. The weight of the robot mechanical structure is an important parameter in this design. In fact, it is used to adjust the gain of the output, resulting in a fuzzy estimator that synthesizes the magic formula for a large model of tyres. Simulation results are reported and discussed.
    Keywords: WMR, Slip Fuzzy estimator TSMC Tyre forces
  • S. Ali A. Moosavian, M. Nabipour* Pages 63-72

    Utilizing orthosis and exoskeletons has drawn a lot of attention in many applications including medical industries. These devices are used in the area of physical therapy to facilitate the patient’s exercises and as an assisting device to help the elderly carry out their daily activities. In this paper, the RoboWalk body-weight support assist device is introduced and its performance is analyzed by studying its influence on a human model. For this purpose, the forward kinematics of the human model and the inverse kinematics of RoboWalk are introduced in the first step. The dynamics of the human and a comprehensive model for RoboWalk are then obtained using the Newton-Euler method without considering the contact forces. These forces are then included in the model using the jacobian of contact points. The obtained models are then augmented to estimate the RoboWalk joint forces and torques, and those of the human model. The Recursive Newton Euler Algorithm and ADAMS software are used to verify the modeling obtained from the non-recursive Newton-Euler algorithm. The recursive algorithm is suitable for implementation purposes due to its low computational cost. After ensuring the accuracy of the obtained models, a control strategy is designed and implemented on RoboWalk. The performance of RoboWalk is then investigated by defining some criteria, e.g. floor reaction force and human model joint torques, before and after using RoboWalk.

    Keywords: Assistive exoskeleton, Body-weight support, Newton-Euler, Human-robot interaction