bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental investigation of mapping and navigation based on certainty grids using sonar sensors
Authors: Lim Jong Hwan , Cho Dong Woo 
Published: March 2009

SUMMARYA mapping and navigation system based on certainty grids for an autonomous mobile robot operating in unknown environment is described. The system uses sonar range data to build a map of the robot's surroundings. The range data from sonar sensor are integrated into a probability map that is composed of two dimensional grids which contain the probabilities of being occupied by the objects in the environment. A Bayesian model is used to estimate the uncertainty of the sensor information and to update the existing probability map with new range data. The resulting two dimensional map is used for path planning and navigation. In this paper, the Bayesian updating model which was successfully simulated in our earlier work is implemented on a mobile robot and is shown to be valid in the real world by experiment.
A nonlinear model-based control of flexible robots
Authors: Pham CM. , Khalil W. , Chevallereau C. 
Published: March 2009

SUMMARYThis paper present a nonlinear, model-based control of flexible link robots. The control task is formulated requiring rigid joints variables to track reference time-varying trajectory and elastic deflection to be damped. The stability and robustness properties of the control scheme are analyzed from a passive energy consideration. A direct adaptive version is also proposed. Extensive evaluation of this approach is performed using experimental validations involving a single-flexible-link and a two-flexible-link horizontal robot. Experimental results show significant performances of the controller under relatively severe working conditions: 700% payload to arm ratio and 20% elastic deflection ratio at highest acceleration stages.
Shear deformation effect in design considerations of flexible manipulators
Authors: Lee Tian-Soon , Lin Yueh-Jaw 
Published: March 2009

SUMMARYIn this paper the role that shear deformation effect plays in flexible manipulator dynamics is investigated and reported. The shear deformation effect of manipulators with three typical cross-sectional geometries, namely, hollow round, hollow square, and hollow rectangle, is studied. In addition, one important issue for manipulator design considerations regarding the influence of the link dimension variations on flexible dynamics is also investigated. The dynamic simulation results show that the shear deformation effect is approximately inverse proportional to the thickness of manipulator link regardless of cross-sectional shapes, if the link length is fixed. It can also be observed that the longer the manipulator link the less shear effect will influence the manipulator deflection, although the frequency of deflection variances becomes less. Based on the simulation results, it is suggested that hollow circular cross-sectional link should be adopted to reduce shear effect for short and thin manipulator links as far as the flexible linkage manipulator design is concerned. For hollow square and hollow rectangular link cross-sections, the manipulator link must be long and thick to avoid significant influences of shear effects.
A New Class of P.I.D. Parameter Adaptation Algorithms for Robot Manipulators
Authors: Jumarie Guy 
Published: March 2009

SUMMARYBy using very simple considerations related to the mechanical Lagrangian itself, one obtains a new general class of parameter adaptation algorithms for robot manipulators, which provides such approaches as PID adaptation schemes. These models could apply to random structural mechanical Systems, subject to the conditon that they are defined by Lagrangians.
Aspects of robot repeatability
Authors: Mooring B. W. , Pack T. J. 
Published: March 2009

SUMMARYOne of the most important specifications associated with a robot manipulator is repeatability. Unfortunately, there are no standard procedures for determining or specifying the repeatability of a robot. This situation has resulted in a good deal of confusion when attempting to use a published repeatability specification to determine if a robot will meet the requirements of an application.The purpose of this paper, therefore, is to propose a systematic procedure for the determination and specification of robot repeatability. To accomplish this, three aspects of repeatability analysis are examined. First, a method of collecting data to study repeatability is discussed. A data acquisition system is described as well as an associated test procedure. Next, a procedure for utilizing the acquired data to develop a repeatability specification for a robot is proposed. This procedure results in a specification of the robot's ability to orient objects as well as the classical specification for positioning repeatability. A methodical approach to determining where in the workspace the repeatability test should be made is also addressed. Finally, an approach is presented whereby the data collected during the repeatability test may be used to determine which joints contribute most to the variations in robot repeatability.
Basic characteristics and stability properties of quadruped crab gaits
Authors: Min Byungeui , Bien Zeungnam , Hwangt† Seungku 
Published: March 2009

SUMMARYIn this paper, we investigate the crab gaits of a quadruped. Some important characteristics that simplify the analysis of crab gaits are presented, and several formulas for optimizing the longitudinal gait stability margin of a quadruped crab gait are derived by incorporating the time weighting factor. The analysis and implementation of the gait have been simplified by employing a pseudo-world coordinate frame as a reference frame for describing footholds and vehicle's motion. We also suggest a unique gait which optimizes gait stability margin according to the range of crab angle. Finally, we consider the effects of variations of footholds on stability and maximum permissible stroke in terms of support boundary angle. The results derived in this paper contain previous works on the forward walking gait as a special case of the crab gait.
CAD-Based off-line programming of painting robots
Authors: Klein Alexandr 
Published: March 2009

SUMMARYThe complex model presented in this paper consists of three main parts: (a) a model of the robot; (b) tools for building and displaying models of workpieces to be painted; (c) a model of the spatial distribution of the paint particles. The simulation process is preceded by the creation of the surface to be coated. A colour graphic display is used for this purpose. The surface appears on the screen together with the robot (hidden line elimination is included). The “spray gun” is installed at the robot's tip and its orientation, performance and other characteristics are to be set. The paint particles sprayed are supposed to form a cone, and by considering its intersection with the surface, the amount of paint delivered to any point can be evaluated and visualized in different colours. The operator simulates the process of painting by moving the spray gun, changing the parameters (speed, distance, etc.), erasing and repeating any step of the process. He can also work in an automatic path generation mode. The result is a near-to-optimal path of the robot's tip (minimizing paint loss and providing a good evenness of coating).
A 3-Dimensional computer animation system with robotic applications
Authors: Siegler Andras , Bathor Miklos , Deri Gabor 
Published: March 2009

SUMMARYThe paper describes a newly developed three-dimensional computer animation system to be used for creating motion programs for a set of actors. The animation package includes a language for describing spatial motion of bodies, as well as an interactive tool to be used for assigning geometrical attributes to them and for guiding and visualizing the play-back of motion programs. One of the main uses of the package is robot programming and motion simulation. A geometrical modeller, which is a an aid in creating the models of animated bodies, is also described.
Optimum path planning of robot arms
Authors: Braibant V. , Geradin M. 
Published: March 2009

SUMMARYThe optimum control of an industrial robot can be achieved by splitting the problem into two tasks: off-line programming of an optimum path, followed by an on-line path tracking.The aim of this paper is to address the numerical solution of the optimum path planning problem. Because of its mixed nature, it can be expressed either in terms of Cartesian coordinates or at joint level.Whatever the approach adopted, the optimum path planning problem can be formulated as the problem of minimizing the overall time (taken as objective function) subject to behavior and side constraints arising from physical limitations and deviation error bounds. The paper proposes a very general optimization algorithm to solve this problem, which is based on the concept of mixed approximation.A numerical application is presented which demonstrates the computational efficiency of the proposed algorithm.
Use of coding and classification systems in the design of universal robotic grippers
Authors: Cho Jeoung S. , Malstromt Eric M. , Even John C. 
Published: March 2009

SUMMARYRecent hardware advances for robot accessories include self changing grippers. A universal wrist has the capability of accessing and pneumatically attaching itself to a limited number of grippers that can be stored in a magazine. This paper addresses the determination of self changing gripper characteristics to permit the grasping of a wide variety of geometric shapes with a limited number of different gripper types.
Using NASREM for real-time sensory interactive robot control
Authors: Lumia R. 
Published: March 2009

SUMMARYThe Flight Telerobotic Servicer (FTS) is a robotic device which will be used to build and maintain Space Station Freedom. The FTS is expected to evolve from its initial capability of teleoperation toward greater autonomy by taking advantage of advances in technology as they become available. In order to support this evolution, NASA has chosen the NASA/NIST Standard Reference model for Telerobot Control System Architecture (NASREM) as the FTS functional architecture. As a result of the definition of generic interfaces in NASREM, the system can be modified without major impact. Consequently, different approaches to solve a problem can be tested easily. This paper describes the implementation of NASREM in the NIST laboratory. The approach is to build a flexible testbed to enhance research in robot control, computer vision, and related areas. To illustrate the real-time aspects of the implementation, a sensory interactive motion control experiment will be described.
Adaptive control of a robot using neural networks
Authors: Pham D. T. , Oh S. J. 
Published: March 2009

SummaryThis paper describes an adaptive control system for an articulated robot with n joints carrying a variable load. The robot is a complex nonlinear time-varying MIMO plant with dynamic interaction between its inputs and outputs. However, the design of the control system is relatively straightforward and does not require any prior knowledge about the plant. This is because the control system is based on using neural networks which can capture the dynamic characteristics of the plant automatically. Three neural networks are employed in total, the first to learn the dynamics of the robot, the second to model its inverse dynamics and the third, a copy of the second neural network, to control the robot.
Optimal kinematic path tracking control of mobile robots with front steering
Authors: Hemami A. , Mehrabi M. G. , Cheng R. M. H. 
Published: March 2009

SummaryThis work concerns the class of wheeled mobile robots with single axis front steering. Because of the relatively low speed of these vehicles their dynamic properties have little effect on their path tracking behaviour. Their motion is, moreover, on a flat environment and can be assumed two dimensional.The kinematics of motion of such a vehicle can be utilized for design of control strategies for maintaining path following stability. In this paper, optimal control technique is implemented to such a system. First, the state space equations governing the motion are derived. The orientation error and the offset from a path form the states and the steering angle is the control input to the system. An optimal controller to minimize the two errors and the steering angle is then sought. The conditions for the existence of the feedback matrix are discussed. The controller structure is defined in terms of the forward speed of the vehicle and, thus, has the advantage of being flexible for speed changes. Numerical illustrative examples, however, demonstrate that variation of the speed has no effect on the controller structure.
Contribution to robots control with parallel degrees of freedom
Authors: Potkonjak V. , Petrović T. 
Published: March 2009

SummaryThis paper considers some problems concerning the motion and the control of large robots. The problem arises when highly nonuniform motion is required. It results in too strong dynamic loads and the robot cannot operate successfully. The solution is found in the introduction of redundancy in the form of parallel degrees of freedom. Kinematics of such a system follows the distributed positioning concept. The control scheme is developed for a one-dimensional redundant robot.
A Teaching Robot for Demonstrating Robot Control Strategies
Authors: Wang D. , Huissoon J.P. , Luscott K. 
Published: March 2009

SUMMARYIt is standard now in undergraduate and graduate courses in robotics to teach the basic concepts of position control design strategies. Due to the geared motors inherent in most educational and industrial manipulators, sophisticated control design strategies such as the inverse dynamics technique cannot be easily demonstrated in a laboratory setting. A direct drive 5-bar-linkage manipulator with reduced motor torque requirements is proposed in this paper for such a purpose. The manipulator dynamics are easily understood by undergraduates and an inverse dynamics control strategy is suggested which can be easily designed by students at the undergraduate level.
Avoidance of obstacles with unknown trajectories: locally optimal paths and path complexity, Part II
Authors: de Lamadrid James Gil , Zimmermanf Jill 
Published: March 2009

SUMMARYContinuing the work presented in part I, ‡ we consider the problem of moving a point robot through a two dimensional workspace containing polygonal obstacles moving on unknown trajectories. We propose to use sensor information to predict the trajectories of the obstacles, and interleave path planning and execution. We define a locally minimum velocity path as an optimal robot trajectory, given only local information about obstacle trajectories. We show that the complexity of a path planning problem can be characterized by how frequently the robot must change directions to approximate the locally minimum velocity path. Our results apply to both robots with and without maximum velocity limits.
Inaccuracy compensation and piecewise circular approximation of parametric paths
Authors: Beazel Vic , Red Edward 
Published: March 2009

SUMMARYA complication to the process of remotely generating tool paths is that mechanism controllers are typically capable of commanding a robot or machine tool to move along linear and circular arc space segments. This paper considers the decomposition of parametrically described, higher-order curvilinear paths into piecewise linear and circular path segments, thereby reducing the data required to store a higher order path.
Motion feasibility of a wheeled vehicle with a steering angle limit
Authors: Wang Yongji , Linnett J.A. , Roberts J.W. 
Published: March 2009

SUMMARYIn the problem of automatically controlling a wheeled vehicle so that a given reference point on the vehicle follows a prescribed path, several factors determine how the task can be accomplished; they are the shape of the path, the initial orientation angle, the steering angle limit and the position of the reference point on the vehicle. If the required steering angle exceeds the limit set by the steering mechanism or the required orientation angle is discontinuous at any point along the path, then the path cannot be followed. This paper investigates this motion feasibility problem, taking steering angle limit into consideration. First of all, we determine the dependence of the continuity of the orientation angle, steering angle and their derivatives on the continuity of the reference path and its derivatives, then discuss .the relationship between the steering angle limit and the feasible deviation angle intervals. Furthermore, we analyze in detail two typical motions, namely straight line motion and circular motion; some simulation results have been given based on a practical vehicle dimension.
Inverse dynamics and feedforward controllers for high precision position/force tracking of flexible joint robots
Authors: Jankowski Krzysztof P. , Elmaraghy Hoda A. 
Published: March 2009

SUMMARYA nonlinear feedback control based on inverse dynamics is proposed for robots with flexible joints during constrained motion task execution. Based on constrained system formalism, the presented control scheme achieves simultaneous, independent control of both position and contact force at the robot end-effector. The method can be directly applied to robot control, or it can be used as the basis for developing other advanced control strategies. In this paper, a. feedforward controller is considered. Issues related to the practical application of the full inverse dynamics and feedforward control algorithms, such as evaluation of feedback variables, the use of predictors to eliminate the time delay of digital control, and the design of robust controllers, are discussed. The results of extensive numerical simulation are used to show the effectiveness of the proposed controllers and to compare their performances. It is shown that it is possible to achieve high precision tracking if the appropriate predictors are used to eliminate the effect of computational delay of the digital controller. Applying a straightforward approach for robustness of the proposed controllers has additionally improved the trajectory tracking accuracy.
Characteristics and signal processing of a proximity sensor
Authors: Li Y.F. 
Published: March 2009

SUMMARYThis paper presents a fibre optic proximity sensor suitable for robotic applications. The sensor characteristics are first identified through experiments. Then the signal processing problem is studied for general applications where no prior knowledge of the sensor environment is assumed. The nonlinear filtering is carried out by applying a Kalman Filter. Particular attention is paid to the target nature dependence of the sensor output. Experimental results are reported by using the sensors on a real robot system.
On flexible link manipulators: modeling and analysis using the algebra of rotations
Authors: Xi F. , Fenton R.G. 
Published: March 2009

SUMMARYIn this paper, a complete model of the elasto-kinematics is formulated in terms of a new kinematic notation, called the algebra of rotations. Based on this formulation, the elegant and concise expressions are derived for the displacement equation and especially the Jacobians governing the motion mapping between the manipulator tip and joint variables as well as link deflections. Introduction of the elasto-kinematics into the elasto-dynamics can directly take into consideration the nonlinear coupling between joint variables and link deflections, and thus improve the result of the elasto-dynamics.
Fundamental problems of robot control: Part I, Innovations in the realm of robot servo-loops
Authors: Arimoto Suguru 
Published: March 2009

SummaryAfter the enthusiasm for creating “intelligent robots” in the early 1980's, progress of robotics research in the past decade has not fulfilled our expectations but revealed various difficulties in understanding motor control by man and implementing intelligent functions in robotic machines. To regain the initiative in the development of intelligent machines, this paper first presents a critical review of the state of the art of robot control and points out the necessity for improving robot servo-loops in order to facilitate skilled and dexterious motions in robotic manipulators and mechanical hands. It is then shown that the introduction of a quasi-natural potential in Lagrange's formulation of robot dynamics gives rise to the design of hyperstable PID servo-loops, which establish global asymptotic stability of set-point control. The hyperstability theoretical framework is then applied to the design of control commands in various control problems, such as hybrid (position/force) control, impedance control, model-based adaptive control, and learning control. In all cases, the passivity concept of residual robot dynamics plays a vital role in conjunction with the concept of feedback connections of two hyperstable nonlinear or linear blocks.
A three dimensional localiser for autonomous robot vehicles
Authors: Kleeman Lindsay 
Published: March 2009

SummaryA novel design of a three dimensional localiser intended for autonomous robot vehicles is presented. A prototype is implemented in air using ultrasonic beacons at known positions, and can be adapted to underwater environments where it has important applications, such as deep sea maintenance, data collection and reconnaissance tasks. The paper presents the hardware design, algorithms for position and orientation determination (six degrees of freedom), and performance results of a laboratory prototype. Two approaches are discussed for position and orientation determination – (i) fast single measurement set techniques and (ii) computationally slower Kalman filter based techniques. The Kalman filter approach allows the incorporation of robot motion information, more accurate beacon modelling and the capability of processing data from more than four beacons, the minimum number required for localisation.
From identification to motion optimization of a planar manipulator
Authors: Gaudin H. , Bessonnet G. 
Published: March 2009

SummaryIdentification of inertia constants and joint frictions of a robot manipulator is achievedin situ, without dismantling operations, by means of specific test motions. The necessary estimation of actuating torques is carried out by measuring, with Hall effect transducers, the current absorbed by the motors which power the system. This identification is accomplished by using a precise methodological order adapted to a planar SCARA type manipulator with two degrees of freedom. The identification of friction laws underscores a hysteresis phenomenon of the dissipative torques. This indicates that friction doesn't result from a simple superposition of a dry friction law and a viscous damping law. The identification results were applied with success to implementation of optimized trajectories computed on the basis of a dynamic criterion. The effective minimization of the performance criterion along the optimized trajectories, according to the corresponding standard trajectories, was verified experimentally by evaluating the motor work and actuator torques.