bluuebunny/crossref_metadata_2025_split huggingface dataset:
Calibration control of robot vertical assembly
Authors: Red Edward , Wang Xuguang , Turner Ed 
Published: July 2007

AbstractCalibration 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

AbstractA 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

AbstractA 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractThe 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

AbstractIntegral 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

AbstractThe 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

AbstractBased 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

AbstractIn 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractThis 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

AbstractA 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

AbstractThis 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

AbstractThis 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

AbstractTo 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

AbstractA 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

AbstractThis 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.
An algorithm for efficient computation of dynamics of robotic manipulators
Authors: He Xiaogeng , Goldenberg A. A. 
Published: July 2007

AbstractThis article presents a recursive algorithm for computation of dynamics of robot manipulators using the concepts of “augmented body” and “barycenter.” This efficient algorithm is proposed for real‐time control. The proposed method of computation is based on Newton‐Euler formalism, and it can be applied to any rigid‐link manipulator with open‐loop kinematic chains with revolute and/or prismatic joints. The computational efficiency of the proposed method is compared with other published methods.
Optimizing the location of assembly tasks in a manipulator's workspace
Authors: Nelson Brad , Donath Max 
Published: July 2007

AbstractOff‐line programming of robotic workcells has become an invaluable tool for the workcell designer, however, current robot programming systems lack the capability to automatically determine the locations for performing assembly operations within the manipulator's workspace. A gradient function of manipulability in Cartesian space was developed based on an explicit determination of the manipulability function and the gradient of the manipulability function in joint space. A modified method of the steepest descent optimization procedure was then used as the basis for an algorithm that automatically locates an assembly task away from singularities within a manipulator's workspace. This algorithm can readily be extended to any nonredundant manipulator.
Acceleration and torque feedback for robotic control: Experimental results
Authors: McInroy John E. , Saridis George N. 
Published: July 2007

AbstractGross motion control of robotic manipulators typically requires significant on‐line computations to compensate for nonlinear dynamics due to gravity, Coriolis, centripetal, and friction nonlinearities. One controller proposed by Luo and Saridis avoids these computations by feeding back joint acceleration and torque. This study implements the controller on a Puma 600 robotic manipulator. Joint acceleration measurement is obtained by measuring linear accelerations of each joint, and deriving a computationally efficient transformation from the linear measurements to the angular accelerations. Torque feedback is obtained by using the previous torque sent to the joints. The implementation has stability problems on the Puma 600 due to the extremely high gains inherent in the feedback structure. Since these high gains excite frequency modes in the Puma 600, the algorithm is modified to decrease the gain inherent in the feedback structure. The resulting compensator is stable and insensitive to high frequency unmodeled dynamics. Moreover, a second compensator is proposed which uses acceleration and torque feedback, but still allows nonlinear terms to be fed forward. Thus, by feeding the increment in the easily calculated gravity terms forward, improved responses are obtained. Both proposed compensators are implemented, and the real time results are compared to those obtained with the computed torque algorithm.