bluuebunny/crossref_metadata_2025 huggingface dataset:
Explicit Path Tracking by Autonomous Vehicles
Authors: Shin Dong Hun , Singh Sanjiv , Lee Ju Jang
Published: March 2009

We have suggested a novel approach to autonomously navigate a full sized autonomous vehicle that separately treats vehicle control and obstacle detection. In this paper we discuss the vehicle control that has enabled our autonomous vehicle to travel at speeds upto 20mph. We point out the limitations of existing schemes that restrict their consideration to kinematic models and show that it is possible to obtain an increase in performance through the use of approximate dynamical models that capture first–order effects. Our approach combines such a modeling philosophy with accurate feedback in world coordinates from sensors that have only recently become available. Experimental results of our implementation on NavLab, a modified van at CMU, are presented.
ELITE: A goal oriented vision system for moving objects detection
Authors: Borghese N. A. , Rienzo M. Di , Ferrigno G. , Pedotti A.
Published: March 2009

A specially designed system for movement monitoring is here presented. The system has a two level architecture. At the first level, a hardware processor analyses in real-time the images provided by a set of standard TV cameras and, using a technique based on the convolution operator, recognizes in each frame objects that have a specific shape. The coordinates of these objects are fed to a computer, the second level of the system, that analyses the movement of these objects with the aid of a set of rules representing the knowledge of the context. The system was extensively tested on the field and the main results are reported.

The whole system can work as a controlling device in robotics or as a general real-time image processor as well as an automatic movement analyser in biomechanics, orthopedic and neurological medicine.
Dextrous telerobotics with force feedback — An overview part 2: control and implementation
Authors: Burdea Grigore , Zhuang Jiachen
Published: March 2009

The control stategy for a dextrous masters is different from the general case of bilateral teleoperation since it models the human hand in much more detail. Such a model is discussed together with the selection of actuators used for force feedback control. Existing prototypes of dextrous masters with force feedback are then reviewed. These are the Servo Controlled Manipulator Device, the Portable Dextrous Force Feedback Master (P.D.M.F.F.), the Remote Handler, and the Advanced Multiple DOF Force Reflective Hand/Wrist Master.
Force-Controlled Assembly of two Objects with a Two-arm Robot
Authors: Dauchez Pierre , Delebarre Xavier
Published: March 2009

The use of a two-arm robot for assembling two objects, with each being held by one arm, is presented. The assembly task is decomposed into an approach phase and an assembly phase. For each phase, we propose a solution for describing the task. For the approach phase, we suggest to describe the task with respect to a mobile reference frame, attached to the end effector of one of the arms. This allows us to take advantage of the redundancy of the system. For the assembly phase, we propose two solutions, both involving some kind of force control. The first one is based upon a position control similar to the one used for the approach phase, with an updating of the reference position through a measurement of the contact forces. The second scheme is derived from a symmetrical hybrid control scheme initially proposed by Uchiyama and Dauchez to control a two-arm robot handling a single rigid object. The main results of this scheme are summarized, and the way of using it for an assembly task is presented. Finally, the experimental setup we have installed to validate our theoretical results is described.
Isoelastic behavior of parallel robots
Authors: Artigue F. , Amirat M. Y. , Pontnau J.
Published: March 2009

This paper presents a particular architecture of a parallel robot which is characterized by a diagonal stiffness matrix. This result suggests the use of a parallel robot in the final phase of insertion as a passive compliance device. The stiffness rate of this device is controlled by the gain of the feedback loop. As the correction of small angular misalignments due to contact forces do not generate lateral errors and vice versa, we have the equivalent of an isoelastic swivel.
Computer Automated Symbolic Modeling of Dynamics of Robotic Manipulators with Flexible Links
Authors: Cetinkunt Sabri , Ittop B.
Published: March 2009

Dynamic equations of chain structured robotic manipulators with compliant links and joints are developed in a non-recursive symbolic form. A program is developed in REDUCE to automate the symbolic expansion of these equations for any given chain structured manipulator. The symbolic non-recursive form of dynamic model is particularly suitable for controller synthesis and real-time control implementations. The link flexibility is included in the formulation using assumed mode shapes. The mode shapes and the parameters that are functions of the mode shapes are kept in symbolic form so that once a symbolic model is generated, different types of mode shapes can be studied using the same model. Because of the structural similarity between the developed equations and the well known rigid manipulator equations, the computer automated symbolic expansion capability presented here are likely to be utilized widely by many other researchers in the area who are already familiar with rigid manipulator problems.
Six degrees of freedom parallel robots with C5 links
Authors: Amirat Y. , Artigue F. , Pontnau J.
Published: March 2009

This paper presents at first a static and kinematic analysis of closed chains mechanisms which permits to deduce different possible fully parallel architectures. Then we focus on a particular parallel architecture with C5 links designed to perform precise assembly tasks. A general modeling of this C5 parallel robot is presented. Two typical assembly tasks in the automotive industry are also proposed; the first one uses the C5 links parallel robot as a left-hand device, while the second one uses it as the terminal tool of a sequential manipulator.
Step lengths and efficiencies of serial-operated and parallel-operated mechanical legs
Authors: McCloy D
Published: March 2009

When a free-ranging walking machine carries its own fuel and power source as well as a payload, it is important to maintain high mechanical efficiency. If the masses of the legs are negligible then, in a straight and level walk, the only power to be generated would be that needed to overcome ground and wind resistance and internal frictions. The paper shows this to be the case when one-input straight-line generating mechanisms are used. However, when two-input mechanisms are used the actuators can work against each other resulting in finite, sometimes large, power requirements. The paper determines the effects of limb lengths and ground clearance on step length and quantifies the power requirements of serial-operated and parallel-operated legs. It shows that parallel-operation offers greater efficiency.
Distributed positioning for redundant robotic systems
Authors: Potkonjak Veljko
Published: March 2009

A new approach to redundant robots is presented. The problem of the multiple solutions of the inverse kinematic is solved by making a special distribution of robot external motions to the redundant number of joint motions. The distribution is made in such a way to separate the smooth transport motion from the relative motion which could be fast and have high acceleration.
Tracking control of flexible robot manipulators with active inertia links
Authors: Jumarie Guy
Published: March 2009

The flexible structure of a robot multi-links manipulator can be either a side effect or, on the contrary, an essential feature. We present a fairly general model to derive the corresponding dynamic equations in quite a systematic and simple way. To this end, we use the Lagrange formulation with strain energy potential and Raleigh (dissipation) functions. The approach can incorporate torsional deformation and aerodynamic friction, and it applies easily to robots working in the sea. The trajectory control appears to be one in the presence of model imprecision, and a slightly modified version of the classical sliding control technique is utilized to design the tracking control of the manipulator. Then we introduce the time-varying inertia link device (carried out by means of sliding masses) which we suggested in earlier work, and we show how it can be used to improve the tracking control scheme above. This paper contributes new ideas concerning flexible multi-links arms and active inertia links.
Collision-free motion planning for two articulated robot arms using minimum distance functions
Authors: Chang C. , Chung M. J. , Bien Z.
Published: March 2009

This paper presents a collision-free motion planning method of two articulated robot arms in a three dimensional common work space. Each link of a robot arm is modeled by a cylinder ended by two hemispheres, and the remaining wrist and hand is modeled by a sphere. To describe the danger of collision between two modeled objects, minimum distance functions, which are defined by the Euclidean norm, are used. These minimum distance functions are used to describe the constraints that guarantee no collision between two robot arms. The collision-free motion planning problem is formulated as a pointwise constrained nonlinear minimization problem, and solved by a conjugate gradient method with barrier functions. To improve the minimization process, a simple grid technique is incorporated. Finally, a simulation study is presented to show the significance of the proposed method.
Deriving complex location data from simple movement sensors
Authors: Gordon J. L. , Williams D. , Hobson C. A.
Published: March 2009

Building Management Systems and Home Automation are, at present, active areas of research and development. One of the unsolved problems within this field is that of Occupant Location within a premises. Computer vision systems are, as yet, too expensive and still not entirely adequate to monitor occupation from every room in a building. The use of existing movement sensors is a cost effective solution but has the disadvantages of not detecting people who are stationary for some time, or giving any indication of how many people are in a room.

This paper addresses the problem of using the collaborative sum of these simple movement sensors in a temporal reasoning scheme to deduce room occupation.
Tactile image computation using a feature extraction algorithm
Authors: Mehdian M.
Published: March 2009

A binary tactile image feature extraction algorithm using image primitive notation and perceptrons is presented. The basic image segments are defined as geometric factors by which the image structure is described so that effective feature values such as image shape, image size, perimeter and texture may be extracted on the basis of local image computation. The local property of the tactile image computation is evaluated by the concept called order of the perceptrons and based on this feature extraction algorithm, an efficient tactile image recognition system is realised.
Kinematic control of planar redundant manipulators by extended motion distribution scheme
Authors: Chung W. J. , Chung W. K. , Youm Y.
Published: March 2009

The kinematic control of a planar manipulator with several-degrees of redundancy has been a difficult problem because of the heavy computational burden and/or lack of appropriate techniques. The extended motion distribution scheme, which is based on decomposing a planar redundant manipulator into a series of nonredundant/redundant local arms (referred to as subarms) and distributing the motion of an end-effector to subarms at the joint velocity level, is proposed in this paper. The configuration index, which is defined as the product of minors corresponding to subarms in the Jacobian matrix, is used to globally guide the redundant manipulators. To enhance the performance of the proposed scheme, a self-motion control, which handles the internal joint motion that does not contribute to the end-effector motion, can be used optionally to guarantee globally optimal manipulation. The repeatability problem for the redundant manipulators is discussed using the proposed scheme. The results of computer simulations are shown and analyzed in detail for planar 8-DOF and 9-DOF manipulators, as examples.
A geometric approach to manipulator path planning in 3D space in the presence of obstacles
Authors: Kirćanski Manja , Timčenko Olga
Published: March 2009

The paper presents a geometric method for collision-free manipulator path planning in 3D Euclidean space with polyhedral obstacles. It ensures that none of the links nor the manipulator tip collide with the objects. The method is computationally very cheap and it does not require intensive off-line preprocessing. Hence, it is real-time applicable if the information about obstacles positions and shapes is obtained from a higher control level. The trajectories generated lie within the reachable workspace. The method is implemented on a VAX 11/750 computer and the simulation results are included.
Design of robots driven by linear servo systems
Authors: Minotti P. , Pracht P.
Published: March 2009

The performance of robotic manipulators is limited by the nature of the control systems which do not satisfactorily integrate the non-linear phenomena associated with the dynamic behavior of the mechanisms. The significant variations in the axial inertias lead to control problems and require an optimization of the mechanical structures in order to improve the stability of the manipulators. This paper proposes mechanical solutions in the domain of dynamic decoupling of robots and demonstrates, using numerical simulations the value of these solutions in terms of control.
The geometry of machining for computer-aided manufacture
Authors: Stacey T. W. , Middleditch A. E.
Published: March 2009

A geometrical methodology for automatic machine tool command generation is introduced. The geometric entities relevant to machine tool operation are unambiguously defined by volume models. A vector sum operator is used to determine regions of the configuration space of the machine tool which correspond to undesired collisions, cavity access and material removal. Some indication of how cutter paths are generated is given and a practical implementation for the case of machining two and a half dimensional components under two and a half axis control is discussed in more detail.
Kinematic path control of robot arms
Authors: Krustev Evgeny , Lilov Ljubomir
Published: March 2009

Path planning of the end effector motion is here treated from the viewpoint of the path invariance under the transformations of its parametrical representation. Thus, a new method for path planning of the robot arm motion is being developed. Both the problems of finding the end effector time optimal motion and the end effector motion with a prescribed velocity profile along a preplanned path are being solved by the employment of this method. Simulation results are presented and some aspects of implementation are also discussed.
A sealing robot system with visual seam tracking
Authors: Sawano Susumu , Ikeda Junichi , Utsumi Noriyuki , Ohtani Yukio , Kikuchi Akira , Ito Yoshimasa , Kiba Hiroshi
Published: March 2009

A new robot system has been introduced which was designed to seal the seams of car body panels. The system has nine degrees of freedom, and includes the following features: (1) A seam tracking servo using a solid-state TV camera is mounted at the robot hand to compensate for the seam deviations. (2) The robot arm is equipped with a flexible mechanism at the wrist to provide a wide working range for the seal nozzle. (3) A two axis orthogonal robot carrier is provided to make the robot follow the work on an indexed conveyor during the sealing operation. This paper deals with the structure and operation of the system and presents test results obtained on a sealing line.
Automated manipulating system for an industrial robot for arc-welding
Authors: Shivarov Nedko , Yanakiev Kostadin
Published: March 2009

An automated manipulating system, which performs the task of loading, positioning and holding of parts in the working area of an industrial robot is discussed in this paper. The system feeds component parts for the lifting mechanisms of electric trucks to be arc-welded by the robot and then removes them, thus completing a predetermined cycle. It is a part of an actual assembly line in a standard workshop for manufacturing electric trucks. The system's operation is described in detail, and the basic technological characteristics of the welding and peripheral equipment are given. Also, some features of an original welding torch cleaning device are described. The principal approach of planning, designing and implementing robotized cells for automatic arc-welding using a robot is also discussed.
Differential relationship of kinematic model and speed control strategies for a computer-controlled robot manipulator
Authors: Ho C. Y. , Jen Sriwattanathamma
Published: March 2009

This paper describes a new approach to obtaining a differential relationship of a robot manipulator via the Theoretical Kinematics method which may expedite computational efforts. The method involves a successive transformation of velocities from the end-effector to the base of the manipulator, link by link, using the relationship of moving coordinate systems. The equations obtained are written in the form suitable for programming on a digital computer. Furthermore, this paper also discusses the speed control model for general robot manipulators and together presents the Inverse Jacobian of cases of underdetermined and overdetermined of joint-controlled variables.
Special configurations of robot-arms via screw theory
Authors: Hunt K. H.
Published: March 2009

Part 1 of the paper* was concerned with the Jacobian of serial robot-arms and its matrix of cofactors; part 2 emphasizes the end-effector's velocity characteristics as affected at special configurations. The displacement about a ‘fixture-point’ is extended dually to a ‘fixture-plane’, and then to a ‘fixture-line’. These fixture-elements serve to highlight the prolixity of special configurations. Reciprocal screws lead to a complete survey of how the end-effector can ‘twist’ when one freedom is lost; extension to loss of more freedoms is explained. Then the fixture-elements are given elementary displacements that allow common requirements to be studied with the minimum of complications. Further investigation is thought to have promise for robot-control.
Separability of pairs of polygons through single translations
Authors: Sack Jörg-Rüdiger , Toussaint Godfried T.
Published: March 2009

Let P = {p1, …,pn} and Q = {q1,…,qm} be two simple polygons in the plane with non-intersecting interiors, the vertices of which are specified by their cartesian coordinates in order. The translation separability query asks whether there exists a direction in which P can be translated by an arbitrary distance without colliding with Q. It is shown that all directions that admit such a motion can be computed in O(nlogm) time, where n > m, thus improving the previous complexity of O(nm) established for this problem. In designing this algorithm a polygon partitioning technique is introduced that may find application in other geometric problems.

The algorithm presented in this paper solves a simplified version of the grasping problem in robotics. Given a description of a robot hand and a set of objects to be manipulated, the robot must determine which objects can be grasped. The solution given here assumes a two-dimensional world, a hand without an arm, and grasping under translation only.
A three axis tactile sensor-probe for robotic use
Authors: Havlík Štefan
Published: March 2009

The paper deals with a three axis reaction force and displacement sensor. The design procedure of the strain gauges sensor for its intended application as a tactile proble is described. The deformable sensor body with strain gauges arrangement allows all three output voltage readings to be directly related with rectangular components of the force displacement vector in a remote contact reference system. The structural orthogonalisation that results in minimal cross component couplings is briefly outlined. The practical use of the designed probe is exemplified by seam following in a robotic welding system.
Adaptive control of an industrial robot
Authors: Karnik Ajit M. , Sinha Naresh K.
Published: March 2009

For the past several years, industrial robots are being used extensively. These robots are generally equipped with relatively simple control systems. Such control systems have proved adequate, but with increased demand on robot performance, there is need for advanced and sophisticated controllers. One of the probelms in the control of robots is that system dynamics change due to several factors such as the orientation of arms and their effective inertia.

Adaptive controllers have the advantage that the system is continuously modelled and controller parameters are evaluated on-line, thus resulting in superior performance. Adaptive controllers can be realized in several ways.

This paper describes the design and performance of an explicit self tuning regulator for a robot arm.
Numerical complexity of decentralized dynamic control laws for manipulator systems
Authors: Vukobratović M. , Kirćanski N.
Published: March 2009

The numerical complexity of robot dynamic models, inverse control structures and decentralized control laws is analyzed in a systematic fashion. Dynamic models of actuators (DC motors and hydraulic cylinders) are taken into account, too. The exact number of floating-point multiplications and additions/subtractions for an n−link manipulator is determined. The results are applied to several typical industrial manipulators. Measuring of computation time for various control structures is realized on an up-to-date 16-bit microcomputer, widely used in robot controllers. Thereby, the real-time applicability and effectively the “price” of different control laws are estimated.
A Distributed On-Line Trajectory Generator for Intelligent Sensory-Based Manipulators
Authors: Zalzala A. M. S. , Morris A. S.
Published: March 2009

An algorithm is presented for the on-line generation of minimum-time trajectories for robot manipulators. The algorithm is designed for intelligent robots with advanced on-board sensory equipment which can provide the position and orientation of the end-effector. Planning is performed in the configuration (joint) space by the use of optimised combined polynomial splines, along with a search technique to identify the best minimum-time trajectory. The method proposed considers all physical and dynamical limitations inherent in the manipulator design, in addition to any geometric path constraints. Meeting the demands of the heavy computations involved lead to a distributed formulation on a multiprocessor system, for which an intelligent control unit has been created to supervise its proper and practical implementation. Simulation results of a proposed case study are presented for a PUMA 560 robot manipulator.
Dextrous Telerobotics with Force Feedback – An Overview. Part 1: Human Factors
Authors: Burdea Grigore , Zhuang Jiachen
Published: March 2009

Complex tasks that need to be performed through teleoperation led to the development of multifinger robot hands. A dextrous master is a multi-DOF controller which is worn by the operator in order to teleoperate these anthropomorphic hands. Force feedback is very useful when there is interaction with the environment. Providing force feedback to dextrous masters is an area of active research. We outline some of the human factors that influence the design of such masters. Of obvious importance is the hand geometry and the desired number of degrees of freedom. Additional criteria relate to the force perception of the hand. Finally, the man-machine impedance is of importance, since at the man/machine interface there are two impedances acting in series. One is the effective impedance of the human operator holding the master controller, the second is the impedance of the master controller being manipulated.
A Variational Approach for Modeling Flexibility Effects in Manipulator Arms
Authors: Meghdari Ali
Published: March 2009

This paper presents a general technique to model flexible components (mainly links and joints flexibilities are considered) of manipulator arms based on Castigliano's theorem of least work. The robotic arms flexibility properties are derived and represented by the matrix of compliance coefficients. Such expressions can be used to determine the errors due to the robotic tip deformations under the application of a set of applied loads at the tip in a Cartesian space. Once these deformations are computed, they may be used to correct for the positional errors arisen from the robotic structural deformations in the motion control algorithms.
Optimizing motion trajectories of dextrous fingers by dynamic programming technique
Authors: Meghdari Ali , Sayyaadi Hassan
Published: March 2009

An optimization technique based on the well known Dynamic Programming Algorithm is applied to the motion control trajectories and path planning of multi-jointed fingers in dextrous hand designs. A three-fingered hand with each finger containing four degrees of freedom is considered for analysis. After generating the kinematics and dynamics equations of such a hand, optimum values of the joints torques and velocities are computed such that the finger-tips of the hand are moved through their prescribed trajectories with the least time or/and energy to reach the object being grasped. Finally, optimal as well as feasible solutions for the multi-jointed fingers are identified and the results are presented.
Generalized predictive control of a robotic manipulator with hydraulic actuators
Authors: Kotzev A. , Cherchas D. B. , Lawrence P. D. , Sepehri N.
Published: March 2009

This paper presents some aspects of the behavior of hydraulically actuated heavy duty manipulators. This category of manipulators is used extensively in large resource based industries and any improvement in efficiency may result in major financial benefits. In this paper an adaptive control algorithm is used for a two rigid link manipulator driven by hydraulic actuators. The dynamic model of the manipulator is derived as well as the models of the hydraulic actuators including compliance, dead time and full dynamics of the servo valves. An adaptive control algorithm is considered since changes occur on-line in the system's parameters. The adaptive algorithm used is Generalized Predictive Control (GPC). The GPC uses a controlled autoregressive integrated moving average (CARIMA) type model and a cost function that minimizes a predicted future output error and future weighted control inputs to the plant, resulting in a sequence of future control increments. The procedure, in this work, does not separate the hydraulic actuator and the link dynamics into separate sub-systems, but controls them as one system. The changes in the system's parameters due to the hydraulics or the link dynamics can be estimated and the coefficients of the model adjusted without the necessity of identifying the exact cause of the changes.

It was found in this work that the variations of the GPC control horizon can lead to faster response during transients and significantly reduced overshoot in the nonlinear hydraulic actuation system. An on-line change of the maximum output horizon is also introduced.

This work shows the analysis and results of a two link manipulator with hydraulic actuators. It can be implemented on any hydraulically actuated manipulator with any number of links and actuators.

Numerical simulations are performed on a Vax 3200 computer and the results are presented.
A systemic approach to pattern recognition
Authors: Emptoz H. , Lamure M.
Published: March 2009

We suggest a new pretopological model for pattern recognition which was introduced to study complex economic systems. The model has its origin in the concept of “neighbour”, which is both primitive and fundamental in pattern recognition. Pretopology enables us to develop a perceptive and topological approach for patterns and to see that problems, apparently different, are in fact identical e.g. clustering and recognition, search of skeletons in image processing and search of an informative learning set. It should be noted that the suggeted model is more than a descriptive one.
Machine tool technology: an extended view
Authors: McKee Keith E.
Published: March 2009

Many of the evolving technologies related to machining will expand the traditional concept of the machine tool industry. Preprocessing of materials into net or near-net shapes will reduce or even eliminate the need for machining operations. Conversion of particles into parts is one generic approach which, when automated, could be integrated into a machining center. Similarly diecasting or squeeze casting could become an integrated part of the machining center for volume production. The machine tool industry could automate die manufacturing so that dies could be made in real time and could justify net shape production for small quantities and rush jobs.

Much and often most of the time and costs within a “machining” operation are generated by secondary operations such as heat treating, plating, and welding–operations done in different parts of or even at different plants. The concept of extending the machining center to include these secondary operations has been considered for several years and to a limited extent, has occurred. Laser extended machining centers provide one possibility for integrating several of the secondary operations with machines at a single site.

Post processing of machined parts at the site of the machining center can result in parts oriented and appropriately presented or packaged for subsequent operations. When several machined parts subsequently become an assembly or subassembly, the concept of machining could be extended to include the assembly.

When machining is considered in this broader context, the technology futures of the machine tool industry are considerably broadened. Smarter machine tools, improved support structures, and high speed machining are important, but competitors are looking at the same opportunities and the competitive advantage is likely to be limited. “Leap frog” improvement depends on some of the less conventional technologies considered in this paper. Broadening of the machine tool horizons is likely to offer the technology path for revitalization and growth of the machine tool industry.
Experimental investigation of mapping and navigation based on certainty grids using sonar sensors
Authors: Lim Jong Hwan , Cho Dong Woo
Published: March 2009

A 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

This 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

In 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

By 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

One 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

In 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

The 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

The 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

The 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

Recent 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

The 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

This 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

This 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

This 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

It 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

Continuing 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

A 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

In 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.