bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of a grey scale tactile array sensor pad for robotic applications
Authors: Driels M. R. , Michael K. M. , Cholakis P. N.
Published: July 2007

Since sensory feedback is an important part of robot control and the acquisition, manipulation, and recognition of objects, incorporating a sense of touch into a robotic system can greatly enhance the performance of that system. This article describes the evaluation of a recently developed low‐resolution tactile array sensor pad system for use in robotic applications. Computer algorithms are developed which acquire data from the sensor pad and display the data on a CRT screen. Vision algorithms are implemented in order to extract the necessary information from the tactile data which will aid in the acquisition, manipulation, and recognition of objects. An object's pose is estimated by calculating its center of gravity (position) and principal axis (orientation). Recognizing an object and distinguishing between different objects is accomplished by implementing algorithms which estimate an object's perimeter (shape) and area (size). This work demonstrates that a low‐resolution tactile array sensor is capable of providing the information that is required for many robotic applications in which objects must be acquired, manipulated, and recognized. Such a system provides a low‐cost alternative to more conventional vision‐based systems.
Mathematical modeling of a robot collision with its environment
Authors: Zheng Yuan‐Fang , Hemami Hooshang
Published: July 2007

In this article the collision of a robot with its environment is studied. In normal applications of a robot arm, a collision takes place because of the velocity of the end effector relative to the object at the time of contract. The collision has effects on the velocities and internal forces of the robotic system. Firstly, the generalized velocities representing joint rates have abrupt changes at the moment of collison with the environment. The mathematical model is derived to establish the quantitative relationship between this abrupt change and the severity of the collision. The latter is represented by either an external impulsive force or the instantaneous change of the linear velocity of the contact point. Secondly, internal to the system, large impulsive forces and torques of constraint may develop at each joint because of the collision. These impulses cause possible damages to the system. The mathematical model is also derived to establish a quantitative relation between the impulsive forces and torquest of constraint and the collision. These two models are applied to a Stanford Arm designed to pick up an object by its end effector, and the consequences of the collision are analyzed.
A kinematics and dynamics simulation of the IBM‐7565 robot using AML
Authors: Goldenberg A. A. , Kelly A.
Published: July 2007

This article presents a kinematics and dynamics simulation of the IBM‐7565 robot using its AML programming language. The kinematics and dynamics models are formulated according to the Denavit‐Hartenberg convention and a recursive Newton‐Euler algorithm, respectively. The simulation is integrated in a CAD software package (CATIA) which is used in robot offline programming and collision/interference analysis. The CAD package software which runs on an IBM 3033 main frame also emulates the AML for automatic programming. The simulation models can be run on the IBM 3033 using the emulator or on the robot's dedicated Series‐1 computer to where the programs are downloaded for execution and control of robot motion.
Improving the absolute positioning accuracy of robot manipulators
Authors: Hayati S. , Mirmirani M.
Published: July 2007

The absolute positioning accuracy of robot manipulator can be increased substantially by updating the nominal link parameters in the control software. This paper presents a general method to estimate the link parameter errors for any serial link manipulator (i.e., n links, and any combination of revolute and prismatic joints). The parameters are estimated through a linear kinematic model which relates the link bias errors to the end‐effector positioning error. Only end‐effector measurements are required instead of individual link measurements to implement this method.
Reliable real‐time robot operation employing intelligent forward recovery
Authors: Smith Richard E. , Gini Maria
Published: July 2007

Modern computer‐controlled robots typically fail at their tasks whenever they encounter an error, no matter how minor. The physical environment of a typical assembly robot is too unstructured to benefit from conventional software approaches to reliability. We present an approach which interfaces the real‐time operation of the robot with an intelligent subsystem that performs error analysis and forward recovery if a failure occurs. Our approach involves a special representation of the robot's program that efficiently tracks the robot's operation in real time and is easy to modify to include automatically generated recovery procedures.
Subminiature binary camera design for inspection and robotic assembly applications
Authors: Driels M. R. , Collins E.
Published: July 2007

The article describes the design and utilization of a small, lightweight digital camera intended to assist in robot assembly tasks and to provide a low cost visual inspection tool. The main operational features of the design are outlined together with some sample applications involving the identification of integrated circuit devices, and the location of assembly sites on a printed wiring board.
Robust discrete nonlinear feedback control for robotic manipulators
Authors: Neuman Charles P. , Tourassis Vassilios D.
Published: July 2007

Nonlinear feedback control algorithms for manipulators utilize a complete (coupled and nonlinear) dynamic robot model to decouple the robot joints. In the companion article1 we outlined the practical problems introduced by modeling inaccuracies, unmodeled dynamics and parameter errors. We then introduced the α‐computed‐torque nonlinear feedback control algorithm which is robust in the presence of the aforementioned error sources. In this article, we apply the insight gained from the α‐computed‐torque algorithm to design a robust discrete‐time (accelerometer‐free) computed‐torque robot‐control algorithm founded upon our discrete dynamic robot model.2 Numerical experiments with the cylindrical robot confirm both the robust disturbance rejection characteristics and the practical applicability of our discrete‐time computer‐torque control algorithm.
A new approach to improve absolute positioning accuracy of robot manipulators
Authors: Ishii M. , Sakane S. , Kakikura M. , Mikami Y.
Published: July 2007

This article describes a new calibration system for robot manipulators which improves their absolute positioning accuracy by using parameter‐estimation algorithms based on the Newton method. When 3D position data of the specified points on a manipulator and the joint encoder values are input to the calibration system, the system estimates the offset values of joint encoders, link lengths, and position and orientation of the manipulator base coordinate system with respect to the world coordinate system which is difficult to obtain by conventional calibration methods. This calibration system can be applied to various manipulator types by just changing the basic kinematic equations. The system employs an algebraic programming system called REDUCE to automatically reduce the manipulator kinematic equation and partial differential calculus in the Newton method. For efficiency, first only the arm part with three degrees of freedom and then the hand part are calibrated. The experimental results demonstrate the effectiveness of this system by reducing the robot's absolute positioning errors to the order of repeatability errors.
Information‐control aspects of sensor systems for intelligent robotics
Authors: Nevins J. L.
Published: July 2007

In order to discuss sensor systems in intelligent robotics or manufacturing systems, it is necessary to classify tasks, controller requirements, as well as the information‐control aspects. This paper classifies tasks as deterministic (principally driven by geometry considerations) and non‐deterministic. The latter are the problems done by people requiring skill involving processes whose process models either do not exist or are poorly understood. Other non‐deterministic tasks involve inspection or data interpretation. The process tasks require adaptive‐learning type control systems and are rich in sensor needs. Automated inspection tasks can be implemented by Engineering‐Based Expert systems with more modest sensor system requirements.
On trajectory generation for flexible robots
Authors: Bayo E. , Paden B.
Published: July 2007

A trajectory based on a Gaussian velocity profile is presented as an alternative to the double square pulse acceleration profile. The new trajectory leads to the fast positioning of the tip of a flexible robot with a minimal excitation of high‐frequency modes. The torques necessary to move the robot according to this trajectory show a very smooth behavior. The absence of high‐frequency content, present when double square pulse accelerations are considered, eliminates the Occurrence of undesired residual vibrations produced by modeling uncemnties at high frequencies. The excellent results obtained suggest the use of this new trajectory for fast and precise positioning of flexible robots.
Issues and approaches of automatic focusing algorithms for intelligent robot eye‐in‐hand system
Authors: Luo Ren C. , Lin Min‐Hsiung
Published: July 2007

The new, fast, automatic focusing algorithms, namely Energy Maximization and Histogram Variance Maximization, for computer vision systems have been presented in this article. These two focusing algorithms have greatly reduced the arithmetical operations needed to perform an automatic focusing operation. Experimental evaluations and comparisons to previously developed algorithms have been performed and the results presented. The improved performance in accuracy and speed of our new algorithms will certainly benefit applications such as distance measurement, target tracking, and scene analysis by the use of computer vision techniques.
General‐purpose inverse kinematics transformations for robotic manipulators
Authors: Ang Marcelo H. , Tourassis Vassilios D.
Published: July 2007

Real‐time robot control requires efficient inverse kinematics transformations to compute the temporal evolution of the joint coordinates from the motion of the end‐effector. The development of a coherent, general‐purpose framework, incorporating position, velocity and acceleration transformations, is the theme of this paper. In this framework, the computational requirements of a new inverse kinematic algorithm are delineated. The algorithm is applicable to serial (open‐chain) manipulators with arbitrary axes of motion. Comparative evaluations of the computational cost of the algorithm demonstrate its efficacy and feasibility for real‐time applications.
Adaptive control strategies for cooperative dual‐arm manipulators
Authors: Seraji H.
Published: July 2007

The article describes three strategies for adaptive control of cooperative dual‐arm robots. In the position‐position control strategy, the adaptive controllers ensure that the end‐effector positions of both arms track desired trajectories in Cartesian space despite unknown time‐varying interaction forces exerted through the load. In the position‐hybrid control strategy, the adaptive controller of one arm controls end‐effector motions in the free directions and applied forces in the constraint directions; while the adaptive controller of the other arm ensures that the end‐effector tracks desired position trajectories. In the hybrid‐hybrid control strategy, the adaptive controllers ensure that both end‐effectors track reference position trajectories while simultaneously applying desired forces on the load. In all three control strategies, the coupling effects between the arms through the load are treated as “disturbances” which are rejected by the adaptive controllers while following desired commands in a common frame of reference. The adaptive controllers do not require the complex mathematical model of the arm dynamics or any knowledge of the arm dynamic parameters or the load parameters such as mass and stiffness. The controllers have simple structures and are computationally fast for on‐line implementation with high sampling rates. Simulation results are given to illustrate the proposed adaptive control strategies.
Visual control of autonomous mobile robot based on self‐organizing model for pattern learning
Authors: Suzuki Hisashi , Arimoto Suguru
Published: July 2007

This article proposes a self‐organizing model for pattern learning together with an application to an autonomous mobile robot system. The self‐organizing model consists of a processing rule prescribed and a memory part being blank at the initial stage. To an input signal, the model searches for a similar signal in the memory, and recalls its related information. If the information accompanied with the input signal differs from the recalled information, the model adds the new information to the memory. It influences the subsequent operations. Thus, the model constructs successively a data‐base in a self‐organizing way. This model can universally learn and reproduce any pattern of input‐output response desired. Two principal functions in autonomous movement, i.e., position identification and obstacle avoiding movement were realized based on the self‐organizing model. Furthermore, a camera type autonomous mobile robot system for indoor was made up. The size of the robot is about 0.7 × 0.7 × 0.7 m, and the weight is about 30 kg. The speed of movement is less than 3 km/h. A small computer that has a 16 bit microprocessor and a 1Mbyte RAM controls the motion of the robot with an extendedClanguage.
An alternative algebra for deriving equations of motion of flexible manipulators
Authors: Everett Louis J.
Published: July 2007

An alternative means for deriving equations of motion of complex systems is demonstrated. Since the method is energy based, it is useful for elastic systems. Because the method can handle vectors expressed relative to rotating coordinate systems, it does not require the introduction of coordinate transformations and thereby produces equations in a simple form. The article shows that Kane's method for rigid body systems is a special case of this alternative method. Two example problems show how the algebra can be applied to rigid and flexible nonholonomic systems.
Engineering design of a multirate nonlinear controller for robot manipulators
Authors: Machado J. A. Tenreiro , Martins Carvalho J. L. De
Published: July 2007

A new multirate nonlinear controller for robot manipulators is described. The algorithm stems from the computed torque method, but has several modifications on its structure, resulting in a more robust controller.

The main philosophy behind those improvements resides on a sound engineering and management of the system resources. Consequently, the use of multirate sampling, memory tables, and predictive action arises naturally from that methodology.

The resulting controller is easy to tune using standard industrial engineering practice; moreover, by alleviating the computational burden its implementation is feasible with present day microprocessors.
Variable structure control of a robotic arm in the presence of uncertainty
Authors: Singh Sahjendra N. , Zakharia Youssef N.
Published: July 2007

Based on the theory of variable structure systems (VSS), control system design for the trajectory control of robotic systems is presented. It is assumed that the parameters of the system are uncertain and unknown frictional torques are acting at the various joints of the arm. For simplicity, the control of a three‐link PUMA arm is considered. For trajectory following, two control laws, CH and Cθ, based on the choice of coordinates of the end effector or joint angles as the controlled outputs, respectively, are derived. It is seen that whereas control Cθ has no singularity, certain singular surfaces arise where feedback elements of CH become infinity. These singular surfaces describe the boundary of the reachable region (workspace). Digital simulation results are presented to show that accurate trajectory following can be accomplished using the control CH or Cθ for large maneuvers of the arm in spite of the uncertainty in the system.
Adaptive control of a manipulator with a flexible link
Authors: Yang Y. P. , Gibson J. S.
Published: July 2007

An adaptive controller for a manipulator with one rigid link and one flexible link is presented. The performance and robustness of the controller are demonstrated by numerical simulation results. In the simulations, the manipulator moves in a gravitational field and a finite element model represents the flexible link.
Inversion techniques for trajectory control of flexible robot arms
Authors: De Luca A. , Lucibello P. , Ulivi And G.
Published: July 2007

A general framework is given for computing the torques that are needed for moving a flexible arm exactly along a given trajectory. This torque computation requires a dynamic generator system, as opposed to the rigid case, and can be accomplished both in an open‐ or in a closed‐loop fashion. In the open‐loop case, the dynamic generator is the full or reduced order inverse system associated to the arm dynamics and outputs. In order to successfully invert the arm dynamics, the torque generator should be a stable system. The stability properties depend on the chosen system output, that is on the robot variables (e.g., joint or end‐effector) to be controlled. The same inversion technique can be applied for closed‐loop trajectory control of flexible robots. A simple but meaningful nonlinear dynamic model of a one‐link flexible arm is used to illustrate different feasible control strategies. Simulation results are reported that display the effects of the system output choice on the closed‐loop stability and on the overall tracking performance.
On the motion of oblique bevel geared robot wrists
Authors: Ma R. , Gupta K. C.
Published: July 2007

In this article, we show that the principle of superposition can be applied for analyzing the spatial motion of a bevel geared three‐roll wrist with nonzero oblique angle. The total motion of the wrist is decomposed into three independent component motions, which are easier to analyze. A superposition tabulation is then constructed to derive the relations among the three wrist joint variables and three coaxial actuation variables. The displacement solution for the wrist joint variables is found by using the zero reference position method.
Stability analysis of wave‐crab gaits of a quadruped
Authors: Zhang Chang‐De , Song Shin‐Min
Published: July 2007

Crab walking is as important as forward walking as applied to walking machine control. Crab walking is especially important to a quadruped since a quadruped has a similar leg geometric layout in both longitudinal and lateral directions. In the studies of forward walking gaits, the wave gait was found to be the optimally stable. In this article, the wave gait is applied to the crab walking of a quadruped and it is modified into four types of wave‐crab gaits according to the range of crab angle. The stability formulae of these wave‐crab gaits are then derived analytically based on the following three stability measurements: stability margin (Sm), body‐longitudinal (or lateral) stability margin (Sbl or Sbt) and crab longitudinal stability margin (Scl). Sm is the true stability index under quasi‐static walking condition. However, the equations are more complicated. Sbl (or Sbt) is simpler and can be used as a good approximation of Sm. Scl was commonly adopted as the stability index in the previous gait studies. Nevertheless, Scl is found to be misleading for a large portion of crab angle range. The analytical results derived in this paper are useful to the geometric design and to the real‐time control of a quadruped.
Sensor integration and data fusion
Authors: Thomopoulos Stelios C. A.
Published: July 2007

The problem of sensor integration and data fusion is addressed. We consider the problem of combining information from diversified sources in a coherent fashion. We assume that information from various sensors may be available in different forms at the fusion. For example, data from infrared (IR) sensors may be combined with range radar (RR) data and further combined with visual images. In each case, data and information from different sensors are presented in a different format which may not be directly compatible for all sensors. Part of the available information may be in the form of attributes and part in the form of dynamical measurements. A generalized evidence processing theory and an architecture for sensor integration and data fusion that accommodates diversified sources of information are presented. Data (or, more generically, information) fusion may take place at different levels, such as the level of dynamics, the level of attributes, and the level of evidence. The common and different aspects of fusion at the different levels are investigated and several practical examples of real world data fusion problems are discussed.
Multiple sensor data association and fusion in aerospace applications
Authors: Blackman S. S. , Broida T. J.
Published: July 2007

This article presents a summary of some of the issues and methods encountered in the use of multiple sensors for surveillance and tracking problems that arise in aerospace and defense. Applications include air traffic control using multiple internetted ground‐based radar sensors, ship‐based air defense systems, and air‐to‐air systems for drug interdiction and for air combat. During the past decade signal and data processing technology has evolved quickly, in terms of computing power, cost, size, and weight. As a result, the automatic fusion of data from multiple sensors has become a viable way of increasing the capabilities and performance of multiple target surveillance and tracking systems, while simultaneously reducing operator or pilot workload. The design, implementation, and performance of automated single sensor systems are fairly well understood, but the same cannot be said of systems that involve fusion of data from multiple sensors. A number of fundamental issues in this area remain unresolved, and the general problem is an area of active research in both the aerospace and the academic communities.
Position control of robot manipulators with elastic joints using force feedback
Authors: Kircanski Nenad , Timcenko Aleksandar , Vukobratovic Miomir
Published: July 2007

Transmission flexibility, as a predominant source of mechanical resonance, often results in inaccurate tracking of prescribed robot trajectories. Thus, the control algorithm must compensate not only for nonlinear dynamics of the arm and payload variations, but also for resonant effects in joints. The compensation for all of these effects results in a very complicated control algorithms which are difficult to apply in practice. In this article we suggest the measurement of torque/force on the output shaft of elastic reducer in order to compensate for elastic effects. The torque measurement can be replaced by the simultaneous measurement of the joint and the motor‐shaft angle. Then, we introduce a dynamic compensator with two zeros and two poles to filtrate the torque signal. It appears that the obtained control law is very simple and compensates for nonlinear system dynamics, variable payload parameters and resonant effects in joints. The proposed control scheme is illustrated by computer simulation of a six‐degree‐of‐freedom robot.
A quadtree‐based path‐planning algorithm for a mobile robot
Authors: Noborio Hiroshi , Naniwa Tomohide , Arimoto Suguru
Published: July 2007

To enable a mobile robot to select automatically a collision‐free path in a given workspace, design of a path‐planning algorithm which must work efficiently in real‐time is crucial. This article proposes a path‐planning algorithm that selects a reasonable collision‐free path tying start and goal points out of a quadtree representation of the robot workspace. The quadtree is obtained from fast conversion of a real image taken through a camera on the ceiling. It represents obstacles and their allocation in the workspace in good time and hence the algorithm is able to find a collision‐free path while following the change of obstacles and their allocation. The algorithm is designed on the basis of “small‐is‐quick” principle. That is, the smaller a search space of the algorithm is, the faster the algorithm selects the shortest path out of the search space. To put the principle in practice, the algorithm investigates a path graph instead of the quadtree while spreading the path graph on the quadtree as small as possible, and selects fast the shortest collision‐free path out of the path graph as a reasonable collision‐free path. Thus the algorithm fulfils its function fast even in a workspace that has a number of obstacles with complicated shape. In comparison with several conventional path‐planning algorithms presented so far, it is shown from experimental results that the proposed algorithm selects faster a reasonable collision‐free robot path than others.
Optimal control of robotic manipulators in the presence of obstacles
Authors: Chen Yao‐Chon , Vidyasagar Mathukumalli
Published: July 2007

In this article, the optimal control problem for (rigid) robotic manipulators in the presence of obstacles is considered. First, two methods for the modeling of obstacles are considered. Through these methods, closed‐form approximations of obstacles in terms of the generalized coordinates of the manipulator are obtained. These expressions are then used to formulate an optimal control problem with state space constraints. The resulting optimal control problem is then solved numerically.
Control of the Utah/MIT dextrous hand: Hardware and software hierarchy
Authors: Speeter Thomas H.
Published: July 2007

This article describes a hardware and software hierarchy for the control of manipulation with the Utah/MIT Dextrous Hand (UMDH). Control algorithms execute within a multiprocessing, shared memory computer environment partitioned into a three tiered hierarchy. Joint level servo algorithms are executed at the lowest level, trajectory generation and communication at the middle level and at the highest level, a new programming language called HPL (Hand Programming Language) is implemented. A functional approach to the control of manipulation is described and the functional philosophy is embedded within HPL. Tasks are specified by the concatenation and linear combination of small functional units called motor primitives. HPL provides an abstraction of the process of manipulation through its use of motor primitives. Hand control programs can be written and easily refined within the HPL programming environment and the resulting programs act as a conveniently annotated description of manipulation tasks.
The local calibration method for robot inaccuracy compensation
Authors: Davies Brady R. , Red W. Edward , Lawson John S.
Published: July 2007

This article presents a local calibration method that is philosophically different from the more contemporary global calibration methods. Local methods seek models of robot performance at the robot distal link measured relative to parts in localized part regions. In contrast, global methods seek to model various sources of robot inaccuracy internal to the robot. For example, a significant global research area is the determination of the actual robot arm structural parameters. Given more accurate estimates of these parameters, global compensation methods propose perturbation techniques or improved kinematic models that can be used to control the as‐manufactured robot. To implement local calibration methods, calibration procedures have been developed to locate tool and sensor tool control frames (TCF's) and to measure robot inaccuracy in localized regions. Using the measured position and orientation (pose) data obtained by hardware sensors, the components of operational inaccuracy are integrated into compensation models. This article discusses compensating model effectiveness and considers the interactions between hardware sensors and part features necessary to extract robot pose measurements automatically and effectively. Applying the relative calibration methodologies presented in this article to a GMF S‐200 six‐axis robot, robot repeatability was reduced by 39% and average localized robot inaccuracy was reduced from 3.4 mm (0.134 inch) to less than 0.86 mm (0.034 inch). The compensated robot inaccuracy is near the unstructured robot repeatability.
Improved configuration control for redundant robots
Authors: Seraji H. , Colbaugh R.
Published: July 2007

This article presents a singularity‐robust task‐prioritized reformulation of the configuration control scheme for redundant robot manipulators. This reformulation suppresses large joint velocities near singularities, at the expense of small task trajectory errors. This is achieved by optimally reducing the joint velocities to induce minimal errors in the task performance by modifying the task trajectories. Furthermore, the same framework provides a means for assignment of priorities between the basic task of end‐effector motion and the user‐defined additional task for utilizing redundancy. This allows automatic relaxation of the additional task constraints in favor of the desired end‐effector motion, when both cannot be achieved exactly. The improved configuration control scheme is illustrated for a variety of additional tasks, and extensive simulation results are presented.
A new solid model HSM and its application to interference detection between moving objects
Authors: Liu Yun‐Hui , Arimoto Suguru , Noborio Hiroshi
Published: July 2007

In order to realize collision‐free coordination of multiple robots, it is crucial to model the robots in a computer adequately and to detect existence or nonexistence of an interference between them on the basis of data structure of the robot models. Motivated by this observation, this article proposes a new solid model named “Hierarchical Sphere Model” (HSM) for modeling moving objects (robots) and presents a feasible algorithm for checking an interference between them on the basis of HSM. HSM arranges region informations in a hierarchical tree structure whose nodes correspond to spherical regions. On the basis of hierarchy of HSM, the algorithm checks only intersections between HSMs' nodes which are close to each other, and hence it works efficiently even if the objects have complicated shape. Furthermore, because a node of HSM represents a spherical region, intersection between, two nodes can be easily found just by calculating the distance between two spheres corresponding to them no matter how the objects move. Finally, the efficiency of the algorithm is demonstrated by several experiments.
A new composite body method for manipulator dynamics
Authors: Lin Shir‐Kuan
Published: July 2007

This article presents a new composite body method for numerically forming the inertia matrix and the bias vector of manipulators, which is more efficient than the other two existing types of composite body methods. The main discrepancy of this one from the existing ones is that all points in a manipulator are observed from the origin of the base frame and the distances are all measured from this origin. The required computations of the present method for the inertia matrix and the bias vector of a manipulator withnrotational joints are (10.5n2+ 38.5n‐ 85)M + (6n2+ 39n‐ 70)A and (12.5n2+ 5.5n+ 3)M + (9n2+n)A, respectively, where “M” denotes multiplications, “A” does additions. In numerically forming the inertia matrix, the present method is more efficient than other methods in the literature for a manipulator with five or more joints; whereas this method is also superior to the recursive Newton‐Euler formulation in computing the bias vector for a manipulator with six or less joints.
Trajectory optimization for kinematically redundant arms
Authors: Carignan Craig R.
Published: July 2007

A review of local optimization methods for resolving joint configurations in underconstrained manipulation tasks is conducted. A new approach is developed for observing joint limits and avoiding obstacles during the trajectory planning. The methodology is used in a four‐link arm example to avoid a workspace singularity and is compared with results using the extended Moore‐Penrose technique. An alternative measure of arm “manipulability” based directly on the rank of the Jacobian is also introduced.
Modeling methods for underwater robotic vehicle dynamics
Authors: Goheen K. R.
Published: July 2007

Models of the open‐loop dynamics for prototype Remotely Operated Underwater Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs) are required for performance prediction and autopilot design. This article describes techniques which can be used to derive these models. The methods may be conveniently grouped into predictive techniques i.e., those which require only vehicle design data and which predict dynamics before the prototype is built and testing techniques i.e., methods which measure open‐loop dynamics from the trials performance of a prototype ROV. The relative benefits and drawbacks of the various methods are examined.
A kinematic analysis of the space station remote manipulator system (SSRMS)
Authors: Crane Carl D. , Duffy Joseph , Carnahan Tim
Published: July 2007

An efficient reverse analysis of three 6‐degree‐of‐freedom (dof) subchains of the 7‐dof SSRMS is presented. The first subchain is formed by locking the seventh joint. The second subchain is formed by locking the second joint, while the third subchain is formed by locking the first joint (the grounded joint is counted as the first joint in the chain). There are a maximum of eight different arm configurations in each of the three subchains, and these were determined by employing a computer‐efficient algorithm, which required the rooting of only at most quadratic polynomials. The algorithms were implemented, and the SSRMS was employed in an animated environment to perform and practice a number of useful tasks for space station servicing. The locking of the second joint has the advantage in that an operator could, at the outset, choose the orientation of the plane that contains the two longest links (the upper arm and forearm) so as to avoid collisions with obstacles. However, it has the disadvantage that when the second joint angle equals 0° or 180°, the manipulator is in a singularity configuration (a singularity analysis of the SSRMS is presented in a second article). It is interesting to note that this plane can also be oriented by specifying the first joint angle. This has the distinct advantage that the plane can be oriented arbitrarily and, in this way, the singularity is avoided.
Dynamic steering control of conventionally steered mobile robots
Authors: Feng Dai , Krogh Bruce H.
Published: July 2007

This article presents an algorithm for dynamically steering an autonomous mobile robot (AMR) along a collision‐free path to a goal using local feedback information. A twolevel navigation algorithm is presented in which a subgoal selection algorithm (SSA) generates visible subgoals to be pursued by the steering control algorithm (SCA). An earlier article presented the SSA in detail, demonstrating how subgoals can be updated while the AMR is moving so that a continuous motion is achieved without stopping to replan the path when new sensor data become available. This study focuses on the SCA. In particular, a general feedback scheme is developed for dynamically steering an AMR to a visible goal in the local obstacle‐free space identified by the SSA. We present the detailed implementation of the SCA for a conventionally steered AMR (CAMR). Simulation results are presented that demonstrate the effectiveness of the combined SSA‐SCA feedback scheme. The algorithm has been successfully implemented on the NavLab at CMU.
Kinematics of a parallel‐serial (Hybrid) manipulator
Authors: Shahinpoor M.
Published: July 2007

Hybrid manipulators are parallel‐serial connection robots that give rise to a multitude of highly articulate robotic manipulators. These manipulators are modular and can be extended by additional modules over large distances. Every module has a hemispherical work space and collective modules give rise to highly dexterous symmetrical work space. In this article, some basic designs and kinematical structures of these robot manipulators are discussed, the associated direct and the inverse kinematics formulations are presented, and solutions to the inverse kinematic problem are obtained explicitly and elaborated upon. These robot manipulators are shown to have a strength‐to‐weight ratio many times larger than the value currently available with industrial or research manipulators. This is due to the fact that these hybrid manipulators are stress compensated and have an ultralight weight, yet are extremely stiff due to the fact that the force distribution in their structure is mostly axial. The means of actuation in these manipulators are entirely prismatic and can be provided by ball‐screws with antibacklash nuts or linear induction motors for maximum precision.
Multiplexed piezoelectric polymer tactile sensor
Authors: Kolesar Edward S. , Reston Rocky R. , Ford Douglas G. , Fitch Robert C.
Published: July 2007

An electrically multiplexed robotic tactile sensor has been realized using a monolithic silicon‐integrated circuit coupled to a piezoelectric polyvinylidene fluoride (PVDF) film. The integrated circuit incorporates 25 sensor electrodes arranged in a symmetrical 5 × 5 matrix. Each electrode occupies a 600 × 600 m̈m square area, and they are separated from each other by 600 m̈m. A 25‐m̈m thick PVDF film was experimentally determined to be compatible with the fabrication process, and also yielded very favorable tactile sensing performance characteristics. The response of the tactile sensor is essentially linear for loads spanning 0.8 to 60 g force (gmf). The response bandwidth is 33 Hz, the hysteresis level is very small, and crosstalk is not a significant problem. A novel precharge bias scheme has been implemented to stabilize the pre‐ and postload sensor response. A rudimentary tactile object image measurement process was evaluated to recognize the shapes of circular, rectangular, toroidal, and hexagonal loads.
Model‐based, sensor‐directed remediation of underground storage tanks
Authors: Christensen B. , Drotning W. , Thunborg S.
Published: July 2007

Sensor‐rich, intelligent robots that function with respect to models of their environment have significant potential to reduce the time and cost for the cleanup of hazardous waste while increasing operator safety. Sandia National Laboratories is performing experimental investigations into the application of intelligent robot control technology to the problem of removing waste stored in tanks. This article describes the experimental environment employed at Sandia with particular attention to the computing and software control environment. Intelligent system control is achieved through the integration of extensive geometric and kinematic world models with real‐time sensor‐based control. All operator interactions with the system are through fully animated, graphical representations that validate all operator commands before execution to provide for safe operation. Sensing is used to add information to the robot system's world model and to allow sensor‐based servo control during selected operations. The results of a first critical features test are reported and the potential for applying advanced intelligent control concepts to the removal of waste in storage tanks is discussed.
A kinematic analysis of the modified flight telerobotic servicer manipulator system
Authors: Crane Carl , Carnahan Tim , Duffy Joseph
Published: July 2007

A reverse analysis of a 6 degree of freedom (dof) subchain of a modified 7 dof flight telerobotic servicer (FTS) manipulator system is presented. The 6 dof subchain is designated as a TR‐RT* chain. At the outset, it was considered that the reverse analysis would be similar to a TTT manipulator analyzed previously for which the third and fourth joints intersect at a finite point. This was not, however, the case and a sixteenth‐degree tan‐half‐angle polynomial was derived for the TR‐RT manipulator. The elimination procedure is interesting and much simpler than the procedures for the general case.
Vision‐based obstacle detection for rotorcraft flight
Authors: Sridhar Banavar , Suorsa Ray , Smith Phillip , Hussien Bassam
Published: July 2007

The ability of rotorcraft to fly at low altitude is hindered by the high pilot workload required to avoid obstacles. The development of automation tools that can detect obstacles in the rotorcraft flight path, warn the crew, and interact with the guidance system to avoid detected obstacles would significantly reduce pilot workload and increase safety. This article describes an obstacle detection approach based on feature tracking and recursive range estimation that takes into account the characteristics of rotorcraft flight. The merits and weaknesses of the approach are discussed using image sequences from the laboratory and from flight. © 1992 John Wiley & Sons, Inc.
The reachability and dexterity of elbow and dual‐elbow robot manipulators
Authors: Emiris Dimitrios M. , Tourassis Vassilios D.
Published: July 2007

The objective of this article is to highlight the reachability and dexterity of dual‐elbow manipulators and provide a comparative evaluation of their capabilities. By necessity, dual‐elbow robots are compared to elbow manipulators, the de facto standard of industrial applications. Although it is well established that the ideal elbow and dual elbow geometries are comparable in terms of workspace optimization, it is shown that the corresponding realistic geometries exhibit distinct properties. Realistic dual‐elbow and elbow manipulators are investigated and the effects of manufacturing distortions on the flexibility and workspace utilization of the two geometries are quantified and contrasted. Realistic dual‐elbow geometries are shown to provide, in general, better reachability and dexterity, especially for manipulators with a large structural frame, and to be less sensitive to parallelism errors. © 1992 John Wiley & Sons, Inc.
An efficient technique for finding the desired global optimum of robotic joint displacement
Authors: Lin Paul P. , Yang An‐Jen
Published: July 2007

For an industrial robot on a daily operation basis such as pick and place, it is desired to minimize the robotic joint displacements when moving the robot from one location to another. The objective of the optimization here is to simultaneously minimize a robot end effector's positional error and the robotic joint displacements. By modifying the searching algorithm in the existing complex optimization method, this article presents a technique for finding the desired global optimum solution more efficiently. To compare the optimum searching capability between the proposed and existing searching algorithms, a modified Himmelblau's function is used as an objective function. The presented technique is then applied to a spatial three‐link robot manipulator for global minimization of the joint displacements. © 1992 John Wiley & Sons, Inc.
Kinematics of an infinitely flexible robot arm
Authors: Choi P. J. , Rice J. A. , Cesarone J. C.
Published: July 2007

This article describes a research effort to develop a command and control algorithm for a proposed flexible robot arm. This robot arm, unlike previous arms, is assumed to be extremely flexible, possessing a large number of degrees of freedom and functioning as a “tentacle.” Algorithms for commanding smooth motion of this arm in the presence of obstacles are developed, including both forward and inverse kinematics. The approach is based on the use of Catmull‐Rom splines and local radius of curvature commands to discrete actuators along the arm's length. Several example trajectories are presented and explained. According to the proposed method, a spline curve algorithm is successfully applied for the configuration of the flexible robot and the accuracy and the collision avoidability of the flexible arm are verified through simulation.
Nonlinear control with end‐point acceleration feedback for a two‐link flexible manipulator: Experimental results
Authors: Khorrami Farshad , Jain Sandeep
Published: July 2007

Experimental results for end‐point positioning of multi‐link flexible manipulators through end‐point acceleration feedback are presented in this article. The advocated controllers are implemented on a two‐link flexible arm developed at the Control/Robotics Research Laboratory at Polytechnic University. The advocated approach in this article is based on a two‐stage control design. The first stage is a nonlinear (1) feedback linearizing controller corresponding to the rigid body motion of the manipulator. Because this scheme does not utilize any feedback from the end‐point motion, significant vibrations are induced at the end effector. To this effect, and to enhance the robustness of the closed‐loop dynamics to parameter variations, the inner loop is augmented with an outer loop based on a linear output LQR design that utilizes an end‐point acceleration feedback. The forearm of the manipulator is significantly more flexible as compared with the upper arm. Experimental and simulation results validate the fact that the end‐effector performance is significantly better with the proposed (1) feedback linearizing control as compared with the linear independent joint PD control. In addition, the nonlinear control offers other advantages in terms of smaller and smoother actuator torques and reducing the effects of nonlinearities. Close conformation between simulation and experimental results validates the accuracy of the model.
Inverse kinematics and inverse dynamics for control of a biped walking machine
Authors: Shih Ching‐Long , Gruver William A. , Lee Tsu‐Tian
Published: July 2007

Analytical techniques are presented for the motion planning and control of a 12 degree‐of‐freedom biped walking machine. From the Newton‐Euler equations, joint torques are obtained in terms of joint trajectories, and the inverse dynamics are developed for both the single‐support and double‐support cases. Physical admissibility of the biped trajectory is characterized in terms of the equivalent force‐moment and zero‐moment point. This methodology has been used to obtain reference inputs and implement the feedforward control of walking robots. A simulation example illustrates the application of the techniques to plan the forward‐walking trajectory of the biped robot. The implementation of a prototype mechanism and controller is also described.
Geometric analysis of antagonistic stiffness in redundantly actuated parallel mechanisms
Authors: Yi Byung‐Ju , Freeman Robert A.
Published: July 2007

Parallel closed‐chain mechanical architectures allow for redundant actuation in the force domain. Antagonistic actuation, afforded by this input force redundancy, in conjunction with nonlinear linkage geometry creates an effective stiffness directly analogous to that of a wound metal spring. A general stiffness model for such systems is derived and it is shown that the constitutive relationship between actuation effort and active stiffness is the second‐order kinematic constraint set relating the actuation sites. The extent of stiffness modulation possible is then evaluated and necessary conditions for full stiffness modulation are obtained. Configuration‐dependent, second‐order, geometric singularities affecting stiffness generation are illustrated in terms of a three‐degree‐of‐freedom parallel spherical mechanism example and discussed in relation to their more commonly investigated first‐order counterparts that affect force and velocity transmission. Finally, a load distribution methodology for simultaneous motion and stiffness generation is introduced, and it is shown that with hyperredundant actuation the internal load state of the mechanism can be controlled independent of its motion and effective stiffness. © 1993 John Wiley & Sons, Inc.