bluuebunny/crossref_metadata_2025 huggingface dataset:
Reliability predictions for integrated circuits from test structure data
Authors: Kleppmann W. G.
Published: July 2007

For the prediction of product reliability from test structure data the observed times to failure have to be fitted to an assumed probability distribution and extrapolated to small failure probabilities. And the probability distribution for the (small) test structure size has to be extrapolated to the corresponding distribution for the (larger) product size.

With respect to the probability distribution it is shown that even in the ‘defect’ dominated case, extreme value distributions do not have to apply. This leads to considerable extrapolation uncertainties.

For the size extrapolation of test structure data to the product the degree of dependence between times to failure of substructures on the same chip is of crucial importance. It can change the predicted reliability by orders of magnitude. A model describing this dependence is given and analyses yielding the required information are suggested.
Bettering operation of Robots by learning
Authors: Arimoto Suguru , Kawamura Sadao , Miyazaki Fumio
Published: July 2007

This article proposes a betterment process for the operation of a mechanical robot in a sense that it betters the next operation of a robot by using the previous operation's data. The process has an iterative learning structure such that the (k + 1)th input to joint actuators consists of the kth input plus an error increment composed of the derivative difference between the kth motion trajectory and the given desired motion trajectory. The convergence of the process to the desired motion trajectory is assured under some reasonable conditions. Numerical results by computer simulation are presented to show the effectiveness of the proposed learning scheme.
Logical sensor systems
Authors: Henderson Tom , Shilcrat Esther
Published: July 2007

Multisensor systems require a coherent and efficient treatment of the information provided by the various sensors. We propose a framework, the Logical Sensor Specification System, in which the sensors can be defined abstractly in terms of computational processes operating on the output from other sensors. Various properties of such an organization are investigated, and a particular implementation is described.
Computational requirements of customized Newton‐Euler algorithms
Authors: Khosla Pradeep K. , Neuman Charles P.
Published: July 2007

To reduce the computational requirements of the Newton‐Euler (N‐E) algorithm for real‐time applications, we customize the algorithm for specific manipulator designs. We analyze the computational requirements of the algorithm for designs incorporating practical kinematic and dynamic parameter simplifications. We illustrate our approach by customizing the N‐E algorithm for the CMU direct drive arm II (DD Arm II). Our customized algorithm reduces the computational requirements of the general‐purpose N‐E algorithm by 56 percent. We describe the hardware implementation of our customized algorithm on a Marinco array processor. Our prototype computes in 1.2 ms the inverse dynamic torques for each trajectory set‐point.
The specification of distributed sensing and control
Authors: Henderson Tom , Hansen Chuck , Bhanu Bir
Published: July 2007

Logical Sensor System Specification (LSS) has been introduced as a convenient means for specifying multi‐sensor systems and their implementations. In this article we demonstrate how control issues can be handled in the context of LSS. In particular, the Logical Sensor Specification is extended to include a control mechanism which permits control information to (1) flow from more centralized processing to more peripheral processes, and (2) be generated locally in the logical sensor by means of a micro‐expert system specific to the interface represented by the given logical sensor. Examples are given including a proposed scheme for controlling the Utah/MIT dextrous hand.
A technique for the detection of robot joint gear tightness
Authors: Dagalakis Nicholas G. , Myers Donald R.
Published: July 2007

A new technique for the examination of gear tightness in robot joint drive systems is presented. A single robot joint is subjected to random excitation while the rest of the joints are constrained. The corresponding link motion is monitored by two accelerometers mounted on the link. The transfer function of the translational component of link acceleration is then obtained. From the half peak magnitude bandwidth of the first resonant frequency it is possible to determine whether the joint gears under testing have a tight or loose meshing. Tests were performed on the wrist rotation joint of an industrial robot in two steady state positions with the end effector loaded and unloaded.
Computational robot dynamics: Foundations and applications
Authors: Neuman Charles P. , Murray John J.
Published: July 2007

In 1984, the authors unveiled the computer program Algebraic Robot Modeler (ARM) for the symbolic generation of complete closed‐form dynamic robot models. In this paper, we introduce computational robot dynamics as the synthesis of classical mechanics and computer software for the symbolic and numeric modeling of robotic mechanisms, and branch‐out in three directions. First, we outline the foundations of computational robot dynamics. From its inception (in 1973), we review chronologically the contributions of prominent roboticists, tracing the parallel development of robot dynamics formulations and computational robot dynamics. We then highlight our research activities, the current capabilities of ARM, and our plans for the continuing development and application of ARM and computational robot dynamics. Finally, we focus on practical applications of computational robot dynamics. We apply ARM to produce examples illustrating the comparative computational requirements of robot dynamics formulations for symbolic processing and customized algorithms for numeric processing.
Adaptation of the IBM 7535 robot for use as a slave in a hierarchical master/slave relationship
Authors: Ward M. , Eberhardt Allen C.
Published: July 2007

A new programming environment for the IBM 7535 robot is introduced. AML/E is replaced by a hierarchical control scheme involving a host and a subservient robot. Application programs are developed on the host, an IBM‐PC XT, in an extended version of the “C” programming language. These extensions allow an application program to be composed of several concurrent processes, one of which is responsible for commanding the robot. To configure the robot as a slave in this relationship, a new operating system was developed for its controller. Written in the same language employed at the host level, it is structured as four concurrent processes managing the robot's resources. An interprocess message‐passing scheme provides a path for master/slave communication. The resultant environment is believed to be superior to the original language AML/E for the following reasons: Concurrency, along with the data and control structures of “C,” is made available to the application programmer. Communication is well structured. The robot's operating system is documented, written in a high‐level language, and open to the user for modification. Due to the significance of integrating the robot into more complex applications involving sensors, these characteristics are felt to be essential in future robots.
A finite‐element approach to control the end‐point motion of a single‐link flexible robot
Authors: Bayo Eduardo
Published: July 2007

A structural finite‐element technique based on Bernoulli‐Euler beam theory is presented which will permit the finding of the torques (or forces) that are necessary to apply at one end of a flexible link to produce a desired motion at the other end. This technique is suitable for the open loop control of the tip motion. It may also provide a good control law for feedback control. The finite‐element method is used to discretize the equations of motion. This method has a major advantage in the fact that different material properties and boundary conditions like hubs, tip loads, changes in cross sections, etc., can be handled in a very simple and straightforward manner. The resulting differential equations are integrated via the frequency domain. This allows for the expansion of the desired end motion into its harmonic components and helps to visualize the complex wave propagation nature of the problem. The performance of the proposed technique is illustrated in the solution of a practical example. Results point out the potential that this technique has in the study of the dynamics and control not only of flexible robots, but also of any other flexible mechanisms like those used in biomechanics, where high precision at the tip of very light flexible arms is required.
Generalized joint model for robot manipulator kinematic calibration and compensation
Authors: Driels Morris R. , Pathre Uday S.
Published: July 2007

A generalized model that goes beyond the usual assumption of “ideal” joint behavior is proposed. The “real” joint has five ancillary degrees of freedom besides the dominant motion. The resulting manipulator transformation with its greater degree of sophistication is expected to help in calibration and compensation of the various kinematic contributions to robot inaccuracy. The procedure to compute this generalized manipulator transformation is presented. The generalized model also results in manipulator differential relationships and these are discussed.
Direct adaptive control of manipulators in cartesian space
Authors: Seraji H.
Published: July 2007

A new adaptive‐control scheme for direct control of manipulator end effector to achieve trajectory tracking in Cartesian space is developed in this article. The control structure is obtained from linear multivariable theory and is composed of simple feedforward and feedback controllers and an auxiliary input. The direct adaptation laws are derived from model reference adaptive control theory and are not based on parameter estimation of the robot model. The utilization of adaptive feedforward control and the inclusion of auxiliary input are novel features of the present scheme and result in improved dynamic performance over existing adaptive control schemes. The adaptive controller does not require the complex mathematical model of the robot dynamics or any knowledge of the robot parameters or the payload, and is computationally fast for on‐line implementation with high sampling rates. The control scheme is applied to a two‐link manipulator for illustration.
Singularities in motion and displacement functions for a 7 degree‐of‐freedom manipulator
Authors: Litvin F. L. , Castelli V. Parenti , Shaheen M.
Published: July 2007

The authors propose a method for the determination of singularities in motion and displacement functions for a seven degree‐of‐freedom manipulator. The manipulator is considered, hereby, as a set of six degree‐of‐freedom manipulators. It is proven that two types of singularities in motion can occur at link positions that are independent and dependent with respect to the trajectory to be executed. The relations between the structure of singularity equations and displacement equations are discussed. The derivation of displacement equations for a manipulator with singularities of the second type is based on the idea of modeling of a manipulator by two open kinematic chains and invariants that may be found for these chains. The inverse kinematic equations and the equations of singularities in motion have been derived using a symbolic computer program which can handle manipulators of general structure (with five, six, and seven degrees‐of‐freedom). This program is written in the Symbolic Computation Language REDUCE.
A systematic formulation of dynamic equations for robot manipulators with elastic links
Authors: Lowl K. H.
Published: July 2007

Although a variety of formulation schemes for the dynamic equations of robot manipulators with rigid links can be found in the literature, an efficient method of the formulation for robot manipulators with elastic links is not well known. Accordingly, this work presents the derivation of the equations of motion for application to mechanical manipulators with elastic links. The formulation is conducted analytically using Hamilton's principle. The resultant equations consist of the terms of inertial, Coriolis, centrifugal, gravitational, and exerted forces. They are expressed in terms of a set of independent generalized coordinates. In contrast to conventional variational approaches, the present method provides an efficient and systematic way for obtaining the compact symbolic equations of flexible manipulator systems. Two examples are presented to illustrate the proposed methodology. Firstly, a three‐link flexible manipulator with three revolute joints is studied. A flexible manipulator consisting of a prismatic joint and a discrete mass is the second model.
A strictly convergent real‐time solution for inverse kinematics of robot manipulators
Authors: Tsai Yusheng T. , Orin David E.
Published: July 2007

Inverse Kinematics has been recognized as an important problem in robotics applications. A robot independent solution can only be obtained through numerical methods, but most solutions which use this approach have problems with convergence especially near singularity points. This article develops a strictly convergent algorithm and a special‐purpose Inverse Kinematics Processor (IKP) to obtain the solution in real time. While the algorithm is based on open‐loop integration of rates, the absolute position deviation is used as a criterion to control the iteration, and a feedback mechanism has been especially designed to eliminate problems with long‐term drift or with initial errors in the solution. The architecture of the IKP is based on a high‐speed floating‐point arithmetic processor and is designed to perform the common matrix‐vector operations efficiently with a minimum processor cycle time. The algorithm has been simulated on the proposed architecture, and the results show its robustness and real‐time capability. For a six degree‐of‐freedom robot manipulator (for which no closed‐form solution exist), the Inverse Kinematics solution may be obtained at an approximate 2 khz rate with an error which is within standard repeatability limits.
Customized computational robot dynamics
Authors: Neuman Charles P. , Murray John J.
Published: July 2007

In 1983 the authors implemented the computer program Algebraic Robot Modeler (ARM) to generate symbolically complete closed‐form and recursive dynamic robot models.1–3Then, in 1985, we incorporated in ARM heuristic rules for the systematic organization of dynamic robot models to reduce the computational requirements of customized forward and inverse dynamics calculations. We resolve the issue of numerical efficiency of customized closed‐form and recursive forward and inverse dynamics algorithms for kinematically and dynamically structured manipulators. We find that ARM‐generated customized closed‐form algorithms are the most computationally efficient calculators of forward and inverse dynamics of three degree‐of‐freedom manipulators. For six DOF predominantly rotational manipulators, ARM‐generated customized recursive algorithms are the most computationally efficient foward and inverse dynamics algorithms; inverse dynamics can be computed in less than one millisecond on commercially‐available processors (in software, without special‐purpose hardware). In our companion article,4we compare the symbolic efficiencies of six robot dynamics formulations for generating closed‐form and recursive models.
Two robot arms in assembly by using impulsive information
Authors: Zheng Yuan F.
Published: July 2007

When two robot arms execute coordinated motions in assembly, collision between the two end‐effectors cannot be avoided. The collision effects on the two coordinating robots include two aspects: abrupt velocity changes of the robot joints and impulsive forces exerting on the contact point as well as on robot joints. Since the direction of the impulsive force exerting on the contact point is related to the relative position and orientation of the two mating parts, the impulsive force can be used to detect the alignment errors of the two end‐effectors. Thus a new assembly method is proposed in this article. The new method uses impulsive information to adjust the position and orientation errors of the two robot arms in assembly, rather than employing a compliance mechanism. The advantage of the new method is that the jamming problem, which is usually associated with compliance methods, never takes place. To make the method practically useful, wrist force sensors are suggested to installed at the wrist of each robot. Dynamic relations between the sensed information and the impulsive force at the contact point are then established. The sensed information thus becomes useful in analyzing the alignment situation. Finally, practical cases are studied to illustrate the use of the new assembly method.
Symbolically efficient formulations for computational robot dynamics
Authors: Neuman Charles P. , Murray John J.
Published: July 2007

In 1983, the authors implemented the computer program Algebraic Robot Modeler (ARM) to generatesymbolicallycomplete closed‐form and recursive dynamic robot models.1–4Then, in 1985, we incorporated in ARM heuristic rules for the systematic organization of dynamic robot models to reduce the computational requirements ofcustomizedforward and inverse dynamics calculations. We compare the symbolic efficiencies of six robot dynamics formulations for generating closed‐form and recursive models. We find that our Lagrange‐Christoffel formulation is the most symbolically efficient generator of closed‐form dynamic robot models. In our companion paper,3we resolve the issue of numerical efficiency of customized closed‐form and recursive algorithms for computing the forward and inverse dynamics of kinematically and dynamically structured manipulators.
Region filling operations with random obstacle avoidance for mobile robots
Authors: Cao Zuo Llang , Huang Yuyu , Hall Ernest L.
Published: July 2007

The article presents a new topic in path planning for mobile robots, region filling. which involves a sweeping operation to fill a whole region with random obstacle avoidance. The approaches for global strip filling and local path searching driven by sensory data procedures are developed. A computer graphic simulation is used to verify the filling strategy available. The research was developed from the program for the design of a robot lawn mower. However, the solution appears generic. The significance is that a problem of wide application and generic solutions for general autonomous mobile robots have been developed.
Collision avoidance for Robot manipulators: Application to Catia/IBM 7565 interface
Authors: Fletcher R. W. , Goldenberg A. A.
Published: July 2007

A collision avoidance algorithm has been developed to augment the capability of an automatic (off‐line) robot path planning (programming) tool. The use of off‐line programming tools for robot task programming is becoming increasingly important, but the advantages to be gained by off‐line programming may be lost if collision‐free path planning capabilities are not included. This article addressed the problem of collision‐free path planning in the context of a gantry type robot. The collision avoidance algorithm described here uses the  to collision‐free path planning. The manipulator and obstacles are modeled as spheres to simplify tests for collision. An important feature of this algorithm is that it permits the manipulation of objects in the robot's environment. When compared against an algorithm from the literature, given a lightly cluttered environment modelled by spheres, the new algorithm finds a collision‐free path much faster. This new algorithm has been implemented as part of the CATIA/IBM 7565 interface which forms an automatic off‐line programming system for the IBM 7565 robot. It has also been implemented as a supervisory collision filter to allow collision‐free control of the robot from the operator's console. In both cases the algorithm has been demonstrated to provide efficient and effective collision avoidance for the IBM 7565 robot.
Inverse dynamic analysis and simulation of a platform type of robot
Authors: Do W. Q. D. , Yang D. C. H.
Published: July 2007

This article presents an algorithm to solve the inverse dynamics for platform type of manipulators using Newton‐Euler equations of motion. We found that the inverse dynamics of the system is governed by thirty‐six linear equations. The number of these simultaneous equations can be reduced to six, if a proper sequence is taken. The relationships between the actuating forces and the shape of the structure are analyzed. Based on the algorithm, computer code for simulation was developed. Three cases were studied. As a result, configurations which minimize the actuating forces are suggested. It is also found that the fluctuation of the driving forces is lesser when the path is closer to the center of the base. These results are believed to be useful in the design and control of this type of manipulating devices.
Decoupling and control laws generation from lagrange formalism
Authors: Cotsaftis M. , Vibet C.
Published: July 2007

The decoupling method is directly applied to the Lagrange formalism. Explicit expressions of control laws are given, allowing for automatic derivation of control algorithms. Finally a 3‐dof robot is used to illustrate the proposed rules.
Numerical filtering for the operation of robotic manipulators through kinematically singular configurations
Authors: Maciejewski Anthony A. , Klein Charles A.
Published: July 2007

The loss of independent degrees of freedom at singular configurations is an inherent characteristic of robotic manipulators. Due to the unavoidable singularity of mechanical wrists, singular configurations cannot be avoided by simply restricting the bounds of the workspace. Techniques for operating at singular configurations without inducing unacceptably high joint velocities or end effector tracking errors are presented. Extensions to the damped least‐squares formulation which incorporate estimates of the proximity to singularities and selective filtering of singular components are illustrated. The generality of the technique presented is illustrated in a computer simulation of a commercially available manipulator operating through singular configurations.
Adaptive gait control for a walking robot
Authors: Kumar Vijay R. , Waldron Kenneth J.
Published: July 2007

Walking vehicles have the potential to emulate the superior off‐road mobility of biological systems. However, it is important to make the walking machine terrain adaptive and versatile, and to minimize man's role as an operator in order to realize this potential. Terrain adaptive locomotion involves intelligent foothold selection and the control of gait to produce the desired motion. This requires a departure from the idealized, structured stepping patterns for statically stable gaits which have been the object of considerable research. A modifiedwave gaitis used to demonstrate that it is possible for the vehicle velocity to be varied continuously in accordance with higher level commands even with irregular, asymmetric, and changing support patterns, A varying duty factor is employed to enable optimal leg cycling frequencies. Implementation of gait control algorithms and results from a computer simulation are also presented.
Dynamic control of redundant manipulators
Authors: Hsu Ping , Mauser John , Sastry Shankar
Published: July 2007

Redundant manipulators provide increased flexibility for the execution of complex tasks. Redundancy is often required to maintain manipulability and avoid obstacles while completing the required task. Self‐motion is the internal (joint) motion of the manipulator that does not contribute to the end effector motion. In this article we provide a dynamic feedback control law that guarantees the tracking of a desired end effector trajectory and provides redundancy resolution by making the self‐motion of the manipulator flow along the projection of a given arbitrary vector field. By choosing this vector field to be the gradient of a cost function, for example, the manipulator can be made to seek an optimum configuration. The effectiveness of the control law is illustrated with simulation results.
Six‐axis force sensor evaluation and a new type of optimal frame truss design for robotic applications
Authors: Bayo E. , Stubbe J. R.
Published: July 2007

The different means currently available for six‐axis wrist force sensor evaluation are discussed, and a unified criteria is proposed that is based on the condition number, the overall static and dynamic stiffness of the sensor, and the strain gauge sensitivity. In this light a new frame/truss type of sensor body design is introduced. The uniqueness of the design lies in the elastic members that exhibit truss (axial deformation), as opposed to the commonly used beam (bending) behavior. Several improvements over previous designs result, including: increased force sensitivity with a consistently low condition number, increased rigidity, and improved design flexibility. In addition, a design methodology is presented that uses optimization theory in combination with finite element analysis, to yield the best possible frame/truss force sensor design for a given set of specified principal forces.
On controller tuning for a flexible‐link manipulator with varying payload
Authors: Yurkovich Stephen , Pacheco Fernando E.
Published: July 2007

In this article experimental results are presented for system identification and control of a single‐link flexible manipulator carrying an unknown, varying payload. The control objective is to maintain endpoint position accuracy in the presence of flexure effects after rapid movement due to a rigid body slew‐angle commanded position. Various time‐domain parameter estimation techniques are used to identify ARMA model representations to be employed in controller tuning schemes for vibration compensation. Only endpoint acceleration measurements and motor shaft angle measurements are utilized in relatively simple PID control schemes, which are tuned as dictated by a varying, unknown payload.
Criteria optimization using self‐motion of a 9‐R redundant robot
Authors: Lam K. P.
Published: July 2007

Using inverse kinematic solutions forself‐motionof a class of 9‐R redundant robots, a conjugate‐gradient based constrained optimization scheme for incremental trajectory planning is formulated. The proposed scheme has been evaluated and proved to be an efficient optimization method for redundancy utilization. It can also be used for studying 7‐R and 8‐R manipulators by simply restricting to one‐variable and two‐variable optimization, respectively. In contrast with other approaches which are based on the Jacobian, our scheme exploits the availability ofclosed‐forminverse kinematic solutions to give more effective and accurate results.
Calibration control of robot vertical assembly
Authors: Red Edward , Wang Xuguang , Turner Ed
Published: July 2007

Calibration methods that apply relative techniques to map robot inaccuracy increase robot flexibility by allowing for greater use and application of off‐line path planning techniques. To successfully implement the off‐line techniques described in this article, methods have been integrated for off‐line tool control frame (TCF) calibration, data base integration, and on‐line robot inaccuracy correction. The TCF calibration methods presented in this article successfully determine the TCF origin of the end‐effectors and sensors attached to the robot distal link to within the robot repeatability. When the methods were applied to a SEIKO DTRAN RT‐3000 robot, the TCP origins were statically predicted correct to within 0.025mm (0.001 in.). On‐line methods determine robot inaccuracy by mapping robot configurations relative to operational parts or to spatial templates, in contrast to the contemporary global mapping approaches. For the Seiko robot the resulting inaccuracy distributions permit simple error correction equations to be applied, improving robot positioning accuracy to less than ±0.1 mm in locally large regions and to within the repeatability of the robot ±0.025 mm) in smaller regions. This represents an order‐of‐magnitude decrease in robot inaccuracy.
An end‐effector based imaging proximity sensor
Authors: Mauer Georg F.
Published: July 2007

A two‐dimensional array of small capacitive sensors detects the distance between each sensor tip and the target object. When touching the surface or operating at close distance, an image of the surface contour is obtained. Each capacitive sensor consists of a thin short lead (line capacitance) embedded in a hard ceramic substrate. The sensor array is rugged and can, due to its small size, be configured to almost any desired shape in order to examine even hard‐to‐reach surfaces. An electronic circuit converts the capacitance variations into voltage signals. The sensing process is controlled by a microcomputer, which addresses the sensors in serial order through a multiplexer, samples the data and linearizes them according to the calibration curve. When compared to resistive touch sensors, the capacitive sensing method offers potentially higher package density and image resolution; another advantage is the capability to detect the presence of objects while approaching, before physical contact is made. A proximity sensor array mounted on a robot end effector can determine geometrical parameters such as edges of surfaces, hole center locations, and the end effector pose (angle of alignment between end effector and target surface).
A feedforward decoupling concept for the control of elastic robots
Authors: Pfeiffer Fried Rich
Published: July 2007

A reference‐oriented procedure for controlling elastic robots is presented. This affords, in a first step, an optimal path planning method generating the reference trajectory. It will be realized by a classical feedforward decoupling scheme. The elastic deviations from this reference are corrected within the feedforward loop by calculation of the joint correction angles putting back the endpoint to its nominal position. In a final step, elastic vibrations of the arms are damped by an additional joint output control system, which uses as an input joint kinematics and strain gauge measurements of the elastic curvatures. The concept has been realized for a laboratory manipulator. Theory and experiments agree very well.
Self motion determination based on actuator velocity bounds for redundant manipulators
Authors: Euler J. A. , Dubey R. V. , Babcock S. M.
Published: July 2007

The movement of redundant manipulator joints that does not cause any end‐effector motion is referred to as its self motion. Control schemes for redundant manipulators utilize its self motion to optimize a performance criterion. Thus, commanded joint motion at each sampling step is the sum of the minimum joint motion required for the desired end‐effector motion and the self motion. However, the amount of self motion is limited by the bounds on actuator velocities, which are limited by the actuator torque bounds. A scheme is presented to determine the magnitude of self motion, the direction of which is determined by a gradient projection scheme. Implementation of this scheme on a Motorola 68020 VMEbus‐based controller of a seven‐degree‐of‐freedom manipulator is described.
Cartesian control of redundant robots
Authors: Colbaugh R. , Glass K.
Published: July 2007

This article presents a Cartesian‐space position/force controller for redundant robots. The proposed control structure partitions the control problem into a nonredundant position/force trajectory tracking problem and a redundant mapping problem between Cartesian control inputFϵRmand robot actuator torqueTϵRn(for redundant robots,m < n). The underdetermined nature of theF→Tmap is exploited so that the robot redundancy is utilized to improve the dynamic response of the robot. This dynamically optimalF→Tmap is implemented locally (in time) so that it is computationally efficient for on‐line control; however, it is shown that the map possesses globally optimal characteristics. Additionally, it is demonstrated that the dynamically optimal F→T map can be modified so that the robot redundancy is used to simultaneously improve the dynamic response and realize any specified kinematic performance objective (e.g., manipulability maximization or obstacle avoidance). Computer simulation results are given for a four degree of freedom planar redundant robot under Cartesian control, and demonstrate that position/force trajectory tracking and effective redundancy utilization can be achieved simultaneously with the proposed controller.
On‐line exploration of an unknown surface by a robotic probe
Authors: Brown David B. , Hemami Hooshang , Istefanopulos Yorgo
Published: July 2007

A control strategy is developed for a robotic probe with tactile sensing to explore an unknown surface without losing contact. Digital computer simulations are performed of a three‐link, planar manipulator exploring an ellipsoidal surface in order to test the control strategy. The equations of motion are written and linear, time‐varying, state‐variable feedback is applied to stabilize and decouple the system. A tactile sensor is simulated to supply the normal force between the robot and the surface. From the magnitude and direction of this force, the desired trajectory is determined. An inverse plant and force feedback are implemented to provide the required input torques to the robot's actuators.
A closed‐loop jacobian transpose scheme for solving the inverse kinematics of nonredundant and redundant wrists
Authors: Chiacchio Pasquale , Siciliano Bruno
Published: July 2007

The solution of the inverse kinematic problem is of the utmost importance in robotic manipulator control. This article proposes a closed‐loop scheme for solving the inverse kinematic problem for nonredundant and redundant wrists based on the computation of the Jacobian transpose. The manipulability measure is suitably introduced as a constraint for redundant wrists, by taking advantage of the null space of the Jacobian matrix. The resulting algorithm provides a computational tool to solve a specified orientation trajectory into a joint trajectory. Numerical results with two spherical wrists show the excellent performance of the scheme.
Robot control system using “intelligent” integrators
Authors: Krikelis Nikos J. , Cacambouras Miltos
Published: July 2007

Integral control is important in practice, but in many applications for robot systems this control is unsatisfactory, due to large initial conditions or disturbances. The overshoot becomes large, the speed of response not fast enough, and path tracking is needed. One cure for this problem is the use of the intelligent integral controller, which is very simple in implementation. This control scheme, as part of a PID controller, is applied to a robot system and its superiority, from the conventional one, becomes clear. The main advantage of this controller is that it gives very satisfactory results, while being rather simple.
Obstacle avoidance for redundant robots using configuration control
Authors: Colbaugh R. , Seraji H. , Glass K. L.
Published: July 2007

The article presents a new and simple solution to the obstacle avoidance problem for redundant robots. In the proposed approach, called configuration control, the redundancy is utilized to configure the robot so as to satisfy a set of kinematic inequality constraints representing obstacle avoidance, while the end‐effector is tracking a desired trajectory. The robot control scheme is very simple, and uses on‐line adaptation to eliminate the need for the complex dynamic model and parameter values of the robot. Several simulation results for a four‐link planar robot are presented to illustrate the versatility of the approach. These include reaching around a stationary obstacle, simultaneous avoidance of two obstacles, robot reconfiguration to avoid a moving obstacle, and avoidance of rectangular obstacles. The simplicity and computational efficiency of the proposed scheme allows on‐line implementation with a high sampling rate for real‐time obstacle avoidance in a dynamically varying environment.
Control of flexible joint robots via external linearization approach
Authors: Lin Lih‐Chang , Yuan King
Published: July 2007

Based on the feedback linearization structure algorithm of differential geometric nonlinear control theory, an external linearization approach to the control of multilink flexible joint robots is considered in this article. The resulting externally linearized and input‐output decoupled closed‐loop system contains a linear subsystem and a nonlinear subsystem. The linear part describing the rigid motor motions is suitable for the design of nominal trajectory following control. However, the nonlinear joint deformation subsystem will cause perturbations in the nominal trajectory. To actively damp out the elastic vibrations and to render the complete closed‐loop system robust to uncertainty in system parameters, a combined LQR stabilizer and servocompensator is used as the internal stabilization and error correcting control. The tracking errors of the end effector caused by the quasi‐static joint deflections due to gravity can be compensated for by taking into account the nominal deflections in the trajectory planning and LQ regulation. A three‐link PUMA type arm is tested via simulation.
An efficient local approach for the path generation of robot manipulators
Authors: Mayorga R. V. , Wong A. K. C. , Ma K. S.
Published: July 2007

In this article an efficient local approach for the path generation of robot manipulators is presented. The approach is based on formulating a simple nonlinear programming problem. This problem is considered as a minimization of energy with given robot kinematics and subject to the robot requirements and a singularities avoidance constraint. From this formulation a closed form solution is derived which has the properties that allows to pursue both singularities and obstacle avoidance simultaneously; and that it can incorporate global information. These properties enable the accomplishment of the important task that while a specified trajectory in the operational space can be closely followed, also a desired joint configuration can be attained accurately at a given time. Although the proposed approach is primarily developed for redundant manipulators, its application to nonredundant manipulators is examplified by considering a particular commercial manipulator.
Experimental study on direct adaptive control of a PUMA 560 industrial robot
Authors: Seraji H. , Lee T. , Delpech M.
Published: July 2007

The article describes the implementation and experimental validation of a new direct adaptive control scheme on a PUMA 560 industrial robot. The testbed facility consists of a Unimation PUMA 560 six‐jointed robot and controller, and a DEC Micro VAX II computer which hosts the RCCL (Robot Control “C” Library) software. The control algorithm is implemented on the Micro VAX which acts as a digital controller for the PUMA robot, and the Unimation controller is effectively bypassed and used merely as an I/O device to interface the Micro VAX to the joint motors. The control algorithm for each robot joint consists of an auxiliary signal generated by a constant‐gain PID controller, and an adaptive position‐velocity (PD) feedback controller with adjustable gains. The adaptive independent joint controllers compensate for the interjoint couplings and achieve accurate trajectory tracking without the need for the complex dynamic model and parameter values of the robot. Extensive experimental results on PUMA joint control are presented to confirm the feasibility of the proposed scheme, in spite of strong interactions between joint motions. The scheme is also implemented for control of the end‐effector motion in Cartesian space. Experimental results validate the capabilities of the proposed control scheme. The control scheme is extremely simple and computationally very fast for concurrent processing with high sampling rates.
A discrete‐time adaptive control scheme for robot manipulators
Authors: Tarokh M.
Published: July 2007

A discrete‐time model reference adaptive control scheme is developed for trajectory tracking of robot manipulators. The scheme utilizes feedback, feedforward, and auxiliary signals, obtained from joint angle measurement through simple expressions. Hyperstability theory is utilized to derive the adaptation laws for the controller gain matrices. It is shown that trajectory tracking is achieved despite gross robot parameter variation and uncertainties. The method offers considerable design flexibility and enables the designer to improve the performance of the control system by adjusting free design parameters. The discrete‐time adaptation algorithm is extremely simple and is therefore suitable for real‐time implementation. Simulations and experimental results are given to demonstrate the performance of the scheme.
Robot arm‐wrist coordination. Part 1. Quantitative rating
Authors: Ang Marcelo H. , Tourassis Vassilios D.
Published: July 2007

The robotic capability for controlled motion depends upon the robot's ability to coordinate its arm and wrist in order to accomplish the desired task. The objective of this article is to define formally the arm‐wrist coordination and to introduce a quantitative measure for it. We develop a mathematical framework that provides for the analysis of the impact of both the fixed manipulator geometry and the changing robot configuration upon the efficiency of arm‐wrist coordination. In the companion paper (Part 2). manipulator design guidelines are then formulated to guarantee task decomposition for any desired robot task. Numerical simulations demonstrate the efficacy of these design guidelines.
The use of the generalized links to determine the minimum inertial parameters of robots
Authors: Khalil W. , Bennis F. , Gautier M.
Published: July 2007

This article presents a new method to determine the minimum set of inertial parameters of robots. The method permits to determine most of the regrouped parameters by means of recursive closed form relations. It is based on the use of a new expression for the kinetic and potential energy of the robot as function of the inertial parameters of the generalized links. The demonstration is seen to be easier than the previous methods and gives a clear idea about the physical meaning of the regrouped parameters.
The modified adaptive Hough transform (MAHT)
Authors: Berger Alan D. , Khosla Pradeep K.
Published: July 2007

A fast and robust algorithm for extracting line segments from an image through use of the Hough Transform is presented. The framework for our algorithm comes from the work of Illingworth and Kittler. We have extended their Adaptive Hough Transform algorithm to handle lines of arbitrary slope, multiple lines, and lines in very low signal to noise environments. We present our Modified Adaptive Hough Transform along with experimental results obtained with data from a tactile sensor.
Model‐based sensory pattern fusion
Authors: Stephanou H. E. , Erkmen A. M.
Published: July 2007

This article describes an evidential pattern classifier for the combination of data from physically different sensors. We assume that the sensory evidence is multiresolutional, incomplete, imprecise, and possibly inconsistent. Our focus is on two types of sensory information patterns: visual and tacticle. We develop a logical sensing scheme by using a model‐based representation of prototypical 3‐D surfaces. Each surface represents a class of topological patterns described by shape and curvature features. The sensory evidence is classified by using aconductivitymeasure to determine which prototypical surface best matches the evidence.
Motion estimation of 3‐D objects using multisensor data fusion
Authors: Luo Ren C. , Yang Woo Suk
Published: July 2007

This article presents an approach to estimate the general 3‐D motion of a polyhedral object using multiple sensor data some of which may not provide sufficient information for the estimation of object motion. Motion can be estimated continuously from each sensor through the analysis of the instantaneous state of an object. The instantaneous state of an object is specified by the rotation, which is defined by a rotation axis and rotation angle, and the displacement of the center of rotation. We have introduced a method based on Moore‐Penrose pseudoinverse theory to estimate the instantaneous state of an object, and a linear feedback estimation algorithm to approach the motion estimation. The motion estimated from each sensor is fused to provide more accurate and reliable information about the motion of an unknown object. The techniques of multisensor data fusion can be categorized into three methods: averaging, decision, and guiding. We present a fusion algorithm which combines averaging and decision. With the assumption that the motion is smooth, our approach can handle the data sequences from multiple sensors with different sampling times. We can also predict the next immediate object position and its motion. The simulation results show our proposed approach is advantageous in terms of accuracy, speed, and versatility.
Integrated sensing for circuit board insertion
Authors: Kelley Robert B. , Sood Deepak , Repko Michael C.
Published: July 2007

To automate tasks like assembly, disassembly, repair and maintenance, the issues arising from environmental uncertainties must be addressed. An integrated sensing approach which addresses uncertainties is presented for two robot systems equipped with multiple sensors. The target tasks involve the insertion of printed circuit boards into cages. Sensors are used to calibrate the robot to the workspace, locate the supply of printed circuit boards and the destination insertion slots. A fingertip lightbeam sensor is used to refine the location information to the precision required for a successful insertion. Two plausible approaches are explored to test some of the sensing concepts. One approach examines blind system sensing strategies; the other examines vision sensing in conjunction with fuzzy reasoning. A controller which is based on fuzzy logic is used to interpret the forces and torques generated by the wrist‐mounted force‐torque sensor during the insertion process. These explorations represent the first steps which lead toward the development of integrated sensing skills to perform generic activities such asinsertandlocate.
A simple model of flexible manipulators with six axes and vibration control by using accelerometers
Authors: Matsuno Fumitoshi , Sakawa Yoshiyuki
Published: July 2007

A simple model of flexible manipulators having a heavy end‐effector is presented by introducing a set of equivalent springs which represent all flexibility of manipulators. The equations of vibrations of the end‐effector and the equations of motion of robot links are derived on the basis of the proposed model. Accelerometers are installed on the end‐effector for measuring the vibrations, and output signals of the accelerometers are fedback for suppressing the vibrations. A feedback control law incorporating a state observer is proposed, and stability problem of the feedback system is treated by using small gain theorem. Several satisfactory experimental results are shown.
Inverse kinematics of calibrated robots
Authors: Ji Zhiming , Leu Ming C.
Published: July 2007

This article presents a new approach for solving the inverse kinematics of calibrated industrial robots. The presented method solves this type of inverse kinematics problem, which has no analytical (explicit) solution, by iteratively employing Pieper's solution for inverse manipulator kinematics. It provides fast and accurate solutions for virtually all calibrated commercial robots.