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Design and Experimental Implementation of Bipedal robot  [PDF]
Sreejith C,Sreeshma K
International Journal of Advanced Computer Research , 2012,
Abstract: Biped robots have better mobility thanconventional wheeled robots, but they tend to tipover easily. To be able to walk stably in variousenvironments, such as on rough terrain, up anddown slopes, or in regions containing obstacles, itis necessary for the robot to adapt to the groundconditions with a foot motion, and maintain itsstability with a torso motion. In this paper, we firstformulate the design and walking pattern for abipedal robot and then a kicking robot has beendeveloped for experimental verification. Finally,the correlation between the design and the walkingpatterns is described through simulation studies,and the effectiveness of the proposed methods isconfirmed by simulation examples andexperimental results.
An Improved ZMP-Based CPG Model of Bipedal Robot Walking Searched by SaDE  [PDF]
H. F. Yu,E. H. K. Fung,X. J. Jing
ISRN Robotics , 2014, DOI: 10.1155/2014/241767
Abstract: This paper proposed a method to improve the walking behavior of bipedal robot with adjustable step length. Objectives of this paper are threefold. (1) Genetic Algorithm Optimized Fourier Series Formulation (GAOFSF) is modified to improve its performance. (2) Self-adaptive Differential Evolutionary Algorithm (SaDE) is applied to search feasible walking gait. (3) An efficient method is proposed for adjusting step length based on the modified central pattern generator (CPG) model. The GAOFSF is modified to ensure that trajectories generated are continuous in angular position, velocity, and acceleration. After formulation of the modified CPG model, SaDE is chosen to optimize walking gait (CPG model) due to its superior performance. Through simulation results, dynamic balance of the robot with modified CPG model is better than the original one. In this paper, four adjustable factors ( , , , and ) are added to the joint trajectories. Through adjusting these four factors, joint trajectories are changed and hence the step length achieved by the robot. Finally, the relationship between (1) the desired step length and (2) an appropriate set of , , , and searched by SaDE is learnt by Fuzzy Inference System (FIS). Desired joint angles can be found without the aid of inverse kinematic model. 1. Introduction Recently, many approaches have been adopted for generation of bipedal walking gait. Some researches [1–3] adopted a simplified dynamic model to generate walking gait calculated through inverse kinematic model which is complex and hence the computation load is high. Inspired by neural science, some researchers investigated central pattern generator (CPG). The prime reason for arousing their interest is that CPG models provide several parameters for modulation of locomotion, such as step stride and rhythm, and are suitable to integrate feedback sensors. Hence, a good interaction between the robot and the environment can be achieved [4]. According to Ijspeert [4], CPG becomes more and more popular in robot community. Taga et al. [5] integrated feedbacks with neural oscillators for unpredicted environment. Yang et al. [6], Shafii et al. [7], and Yazdi et al. [8] utilized TFS to formulate ZMP-based CPG model as the basic walking pattern of bipedal robot. Or [9] presented a hybrid CPG-ZMP control system for flexible spine humanoid robot. Aoi and Tsuchiya [10] proposed a locomotion control system based on CPG model for straight and curved walking. Farzenah et al. [11] noted that many researches on CPG model are designed for specific motion only and thus cannot generate
Bipedal nanowalker by pure physical mechanisms  [PDF]
Juan Cheng,Sarangapani Sreelatha,Ruizheng Hou,Artem Efremov,Ruchuan Liu,Johan RC van der Maarel,Zhisong Wang
Quantitative Biology , 2013, DOI: 10.1103/PhysRevLett.109.238104
Abstract: Artificial nanowalkers are inspired by biomolecular counterparts from living cells, but remain far from comparable to the latter in design principles. The walkers reported to date mostly rely on chemical mechanisms to gain a direction; they all produce chemical wastes. Here we report a light-powered DNA bipedal walker based on a design principle derived from cellular walkers. The walker has two identical feet and the track has equal binding sites; yet the walker gains a direction by pure physical mechanisms that autonomously amplify an intra-site asymmetry into a ratchet effect. The nanowalker is free of any chemical waste. It has a distinct thermodynamic feature that it possesses the same equilibrium before and after operation, but generates a truly non-equilibrium distribution during operation. The demonstrated design principle exploits mechanical effects and is adaptable for use in other nanomachines.
Trajectory control of a bipedal walking robot with inertial disc  [PDF]
Carlos Eduardo de Brito Novaes,Paulo Sergio Pereira da Silva,Pierre Rouchon
Mathematics , 2013,
Abstract: In this paper we exploit some interesting properties of a class of bipedal robots which have an inertial disc. One of this properties is the ability to control every position and speed except for the disc position. The proposed control is designed in two hierarchic levels. The first will drive the robot geometry, while the second will control the speed and also the angular momentum. The exponential stability of this approach is proved around some neighborhood of the nominal trajectory defining the geometry of the step. This control will not spend energy to adjust the disc position and neither to synchronize the trajectory with the time. The proposed control only takes action to correct the essential aspects of the walking gait. Computational simulations are presented for different conditions, serving as a empirical test for the neighborhood of attraction.
Gait trajectory generation for a five link bipedal robot based on a reduced dynamical model  [PDF]
Yosra Arous,Olfa Boubaker
Computer Science , 2014, DOI: 10.1109/MELCON.2012.6196594
Abstract: In this paper, a simple trajectory generation method for biped walking is proposed. The dynamic model of the five link bipedal robot is first reduced using several biologically inspired assumptions. A sinusoidal curve is then imposed to the ankle of the swing leg's trajectory. The reduced model is finally obtained and solved: it is an homogeneous second order differential equations with constant coefficients. The algebraic solution obtained ensures a stable rhythmic gait for the bipedal robot. It's continuous in the defined time interval, easy to implement when the boundary conditions are well defined.
Asymptotically Stable Walking of a Five-Link Underactuated 3D Bipedal Robot  [PDF]
Christine Chevallereau,Jessy W. Grizzle,Ching-Long Shih
Computer Science , 2010, DOI: 10.1109/TRO.2008.2010366
Abstract: This paper presents three feedback controllers that achieve an asymptotically stable, periodic, and fast walking gait for a 3D (spatial) bipedal robot consisting of a torso, two legs, and passive (unactuated) point feet. The contact between the robot and the walking surface is assumed to inhibit yaw rotation. The studied robot has 8 DOF in the single support phase and 6 actuators. The interest of studying robots with point feet is that the robot's natural dynamics must be explicitly taken into account to achieve balance while walking. We use an extension of the method of virtual constraints and hybrid zero dynamics, in order to simultaneously compute a periodic orbit and an autonomous feedback controller that realizes the orbit. This method allows the computations to be carried out on a 2-DOF subsystem of the 8-DOF robot model. The stability of the walking gait under closed-loop control is evaluated with the linearization of the restricted Poincar\'e map of the hybrid zero dynamics. Three strategies are explored. The first strategy consists of imposing a stability condition during the search of a periodic gait by optimization. The second strategy uses an event-based controller. In the third approach, the effect of output selection is discussed and a pertinent choice of outputs is proposed, leading to stabilization without the use of a supplemental event-based controller.
Adaptive Fractional PID Controller for Robot Manipulator  [PDF]
H. Delavari,R. Ghaderi,N. A. Ranjbar,S. H. HosseinNia,S. Momani
Physics , 2012,
Abstract: A Fractional adaptive PID (FPID) controller for a robot manipulator will be proposed. The PID parameters have been optimized by Genetic algorithm. The proposed controller is found robust by means of simulation in a tracking job. The validity of the proposed controller is shown by simulation of two-link robot manipulator. The result then is compared with integer type adaptive PID controller. It is found that when error signals in the learning stage are bounded, the trajectory of the robot converges to the desired one asymptotically.
Adaptive Control of 4-DoF Robot manipulator  [PDF]
P. Mironchyk
Computer Science , 2015,
Abstract: In experimental robotics, researchers may face uncertainties in parameters of a robot manipulator that they are working with. This uncertainty may be caused by deviations in the manufacturing process of a manipulator, or changes applied to manipulator in the lab for sake of experiments. Another situation when dynamical and inertial parameters of a robot are uncertain arises, is the grasping of objects by a manipulator. In all these situations there is a need for adaptive control strategies that would identify changes in dynamical properties of manipulator and adjust for them. This article presents a work on designing of an adaptive control strategy for 4-DoF manipulator with uncertain dynamical properties, and outcomes of testing of this strategy applied to control of simulator of robot.
Peg-in-hole insertion method based on adaptive impedance control

LU Jun,YAN Jing-ping,CHEN Jun-jie,
芦 俊

控制理论与应用 , 2003,
Abstract: A peg-in-hole insertion method based on adaptive impedance control is presented. The reference position of robot end-effector is modified according to force information through adaptation law, which makes the peg move in the direction that reduces jamming forces, and finally the insertion is accomplished. This method is simple and the modification can be computed on-line, so it satisfies the requirement of real-time control. Simulation results are given to verify its effectiveness.
Determination of kinematic parameters of a passive bipedal walking robot moving on a declined surface by image processing  [PDF]
A. Bagheri,M. Alitavoli,A. Hajiloo,S. Basiri
Journal of Achievements in Materials and Manufacturing Engineering , 2006,
Abstract: Purpose: This paper describes the design and manufacturing of the mechanisms that are able to move on a slope according to its gravity.Design/methodology/approach: After presenting the governing equations and the dynamics of the robot, a computer simulation is developed. A comparison between the results from the physical model and the results from the numerical simulation is done to check the validity of the project.Findings: This robot is able to move down on slope with a minimum tangent based on the gravity and without any controller or any supplier.Research limitations/implications: Image processing has blind nodes in some frames and can not determine node positions and at this paper a method for getting rid of that problem has been developed. Position accuracy depends on ability of processing unit.Practical implications: This method could be used for finding of kinematic parameters of each manipulator while moving.Originality/value: This paper describes a method for finding kinematic parameters of a passive robot by image processing.
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