Showing papers in "Journal of Robotic Systems in 1984"
TL;DR: A betterment process for the operation of a mechanical robot in a sense that it betters the nextoperation of a robot by using the previous operation's data is proposed.
Abstract: 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.
3,222 citations
TL;DR: A framework is proposed, 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.
Abstract: 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.
203 citations
TL;DR: A Newton-Raphson numerical procedure based on a composite Jacobian which now includes rows for all members under constraint may be applied to solve the inverse kinematic problem for a manipulator of any mechanical configuration without having to derive beforehand a closed-form solution.
Abstract: An inverse kinematic analysis addresses the problem of computing the sequence of joint motion from the Cartesian motion of an interested member, most often the end effector. Although the rates and accelerations are related linearly through the Jacobian, the positions go through a highly nonlinear transformation from one space to another. Hence, the closed-form solution has been obtained only for rather simple manipulator configurations where joints intersect or where consecutive axes are parallel or perpendicular. For the case of redundant manipulators, the number of joint variables generally exceeds that of the constraints, so that in this case the problem is further complicated due to an infinite number of solutions. Previous approaches have been directed to minimize a criterion function, taking into account additional constraints, which often implies a time-consuming optimization process. In this article, a different approach is taken to these problems. A Newton-Raphson numerical procedure has been developed based on a composite Jacobian which now includes rows for all members under constraint. This procedure may be applied to solve the inverse kinematic problem for a manipulator of any mechanical configuration without having to derive beforehand a closed-form solution. The technique is applicable to redundant manipulators since additional constraints on other members as well as on the end effector may be imposed. Finally, this approach has been applied to a seven degree-of-freedom manipulator, and its ability to avoid obstacles is demonstrated.
64 citations
TL;DR: The dynamics of a multi-linkage model of natural or man-made systems with arbitrary holonomic and non-holonomic constraints at the joints are formulated and nonlinear control strategies for postural balance and rhythmic motion are presented.
Abstract: The dynamics of a multi-linkage model of natural or man-made systems with arbitrary holonomic and non-holonomic constraints at the joints are formulated. The formulation is equally applicable to movements on the ground or in the air. Nonlinear control strategies for postural balance and rhythmic motion are presented. A predictive algorithm to compensate for computation or transmission delay is proposed. Digital computer simulations are presented to demonstrate the effectiveness of the control strategy for a five-link three-dimensional biped.
50 citations
TL;DR: This paper presents the study of an adaptive control which tracks a desired time-based trajectory as closely as possible for all times over a wide range of manipulator motion and payloads both in joint-variable coordinates and Cartesian coordinates.
Abstract: This paper presents the study of an adaptive control which tracks a desired time-based trajectory as closely as possible for all times over a wide range of manipulator motion and payloads both in joint-variable coordinates and Cartesian coordinates. The proposed adaptive control is based on the linearized perturbation equations in the vicinity of a nominal trajectory. The controlled system is characterized by feedforward and feedback components which can be computed separately and simultaneously. The feedforward component computes the nominal torques from the Newton-Euler equations of motion either using the resolved joint information or the joint information from the trajectory planning program. This computation can be completed in O(n) time. The feedback component consisting of recursive least square identification and one-step optimal control algorithms for the linearized system computes the perturbation torques in O(n3) time. Because of the parallel structure, the computations of the adaptive control may be implemented in low-cost microprocessors. A computer simulation study Was conducted to evaluate the performance of the adaptive control in joint-variable coordinates for a three-joint robot arm. The feasibility of implementing the adaptive control in Cartesian coordinates using present day low-cost microprocessors is discussed.
29 citations
TL;DR: As a new and successful approach the application of various hierarchical decision strategies in connection with extremely time-efficient evaluation of decision tables is presented, based on a suitable description of the actual possible collision spaces.
Abstract: For effective application of industrial robots in flexible manufacturing systems and in automatic assembly, guided automatic collision avoidance is an important and—in spite of many applications—so far unsolved problem. The basis is unconstrained path control of each robot controlled, for example, by optical sensors in connection with different priority levels assigned to the robots. Iterative, time-consuming, hierarchical control methods are not applicable due to the complexity and the real-time constraints of this task. As a new and successful approach the application of various hierarchical decision strategies in connection with extremely time-efficient evaluation of decision tables is presented. This concept is based on a suitable description of the actual possible collision spaces.
23 citations
TL;DR: A manipulator model which has been used to simulate and control a real robot arm is presented and a method of describing the arm by its rotational characteristics is presented.
Abstract: The ability to mathematically model the movement of a robot manipulator is a prerequisite to the understanding of the key factors that influence a manipulator's performance. This paper presents a manipulator model which has been used to simulate and control a real robot arm. A method of describing the arm by its rotational characteristics. a set of equations called the “Inverse Arm” and an algorithm called the “Forward Arm” are presented. The Forward Arm simulates the movement of an arm and the Inverse Arm provides a means of computing the correct voltages to apply to an arm to achieve a desired movement.
22 citations
TL;DR: To simplify the obstacle description in the computer, a “pillar” model of the bounding polyhedra is constructed and fast decision making is accomplished by structuring a finite number of possible collision avoidance paths.
Abstract: Maneuvering an industrial robot to avoid a collision with obstacles in real time involves not only the fast obstacle detection and descripton, but also fast decision making. The problem is complicated since no a priori knowledge about obstacles is assumed. In addition, they may appear in the robot's path unexpectedly. To detect and describe the three-dimensional obstacles, stereo cameras are used to collect environmental images. Through the top view of the workspace, the cameras furnish the silhouette as well as heights of obstacles. To speed up the image processing, the pixel array is grouped into patches and the maximum height of each patch is determined. TO simplify the obstacle description in the computer, a “pillar” model of the bounding polyhedra is constructed. Fast decision making is accomplished by structuring a finite number of possible collision avoidance paths. Path feasibility is determined at the “module aisle” level while optimization is performed at the subpath level so that the magnitude of processing effort is reduced from the order of 6 to 3 × 6.
15 citations
TL;DR: An on-line parameter estimation algorithm based on the least-squares criterion is used to determine the parameter values along the path at the operating instances and a self-tuning adaptive controller is designed by minimizing a chosen performance criterion.
Abstract: The detailed model for the motion of a manipulator system is linearized along a specific path. An on-line parameter estimation algorithm based on the least-squares criterion is used to determine the parameter values along the path at the operating instances. Based on the estimated parameter values, a self-tuning adaptive controller is designed by minimizing a chosen performance criterion. Simulation results as well as experimental results are presented to demonstrate the approach. Certain aspects of the implementation are discussed.
13 citations
TL;DR: The control of a three-link planar robot, whose parameters roughly match a small commercially available arm, is considered and a control strategy is presented with nonlinear position and velocity error feedback gains which are state dependent.
Abstract: The control of a three-link planar robot, whose parameters roughly match a small commercially available arm, is considered. The end effector of the arm moves along a specified trajectory on a surface with dry friction while maintaining a prespecified constant pressure against the surface both with and without force sensors at the tip. A control strategy is presented with nonlinear position and velocity error feedback gains which are state dependent. Digital computer simulations of the motion are provided for comparison purposes and for demonstrating the effectiveness of this strategy.
9 citations
TL;DR: This work considers twenty eight models for the finger having three joints, and performs a simulation of their ability to grasp various shapes stably, and proposes the wrap-up rate to be used for the evaluation of the stability of grasping.
Abstract: An appropriate arrangement of finger joints is very important since the stability of grasping an object greatly depends on that arrangement. Multijointed fingers can grasp an object with many points of contact each of which is pressed against the object as if wrapping up that object. The amount of the wrapped up area and the form of the finger when an object is grasped are therefore important factors for determining the stability of grasping. We propose the wrapping factor to be used for the evaluation of the stability of grasping by using these factors. We consider 28 models for the finger having three joints, and perform a simulation of their ability to grasp various shapes stably. Based on the simulation results, an appropriate arrangement of lengths between phalanges for a multijointed finger is presented.
TL;DR: This article describes a sensor-based obstruction avoidance technique that, if implemented on the on-board computer of a mobile robot, would enable the robot to move through an unknown environment.
Abstract: This article describes a sensor-based obstruction avoidance technique. This technique, if implemented on the on-board computer of a mobile robot, would enable the robot to move through an unknown environment. The proposed approach is driven by sensory data. The robot thus senses and adapts to the changes in the environment. The software also does path planning. As more information about the environment is obtained the robot's path planning capabilities improve. Illustrative examples are used to describe the algorithms.
TL;DR: This article describes the operation and properties of electro-optical imaging sensors and presents a relatively comprehensive overview of the parameters used to describe imaging sensors.
Abstract: Robot vision, robotics vision, and computer vision are terms that have evolved over the past few years to include two separate but related functions that provide visual sensing for computerdriven robots. These two functions are “electro-optical imaging” and “image processing.” The purpose of electro-optical imaging is to convert optical radiation to an appropriate electronic signal for input to the robot's computer; whereas, the purpose of image processing is to extract useful information from the electronic image provided by the sensor. This article deals with the electro-optical sensing part of robot vision. It describes the operation and properties of electro-optical imaging sensors. The fundamental concepts of optical radiation, optical radiation quantities and units, and photon energies are defined. The fundamental principles for detecting optical radiation and definitions for the primary performance measures for optical detectors are given. A relatively comprehensive overview of the parameters used to describe imaging sensors is presented. Factors affecting these parameters and obtainable sensor performance are compared. Example design analyses are presented to show the interaction of various performance measures.
TL;DR: An attempt is made to provide a comparative analysis of all the stated control algorithms and to point out the advantage of decentralized control concept.
Abstract: Different concepts for dynamic control of manipulation robots are presented. Principles for the synthesis of optimal control, optimal regulator, “inverse problem” technique, force feedback, decoupled control, and decentralized control are considered. An attempt is made to provide a comparative analysis of all the stated control algorithms and to point out the advantage of decentralized control concept.
TL;DR: The structure of the dynamical system is provided using two complementary approaches based on Lagrangian techniques while the second is a modified version of Hollerbach's recursive formula.
Abstract: Beginning with an outline of the accepted methods for kinematic analysis of robot manipulators, the structure of the dynamical system is provided using two complementary approaches. The first of these is based on Lagrangian techniques while the second is a modified version of Hollerbach's recursive formula. The results of both methods are demonstrated for the particular case of a PUMA robot, and the code for both algorithms is provided in the Appendix.
TL;DR: A generalized inversion technique and algorithm is presented for the purpose of computing the 9n coefficients pertaining to the three segments—i.e., liftoff, transitory, and setdown— of a motion trajectory of an n-axis robot manipulator.
Abstract: A generalized inversion technique and algorithm is presented for the purpose of computing the 9n coefficients pertaining to the three segments—i.e., liftoff, transitory, and setdown—of a motion trajectory of an n-axis robot manipulator. The technique and the computer program presented is general enough to be immediately applicable to an n-axis robot manipulator if only the desired initial and final position, velocity, acceleration, as well as the intermediate “via” positions are given. A number of examples are presented for a wide spectrum of these constraint conditions on the desired motion trajectories.
TL;DR: The problem of picking up single cylindrical objects using a robot equipped with a vision system and how the robot defines the position of objects located within the workcell is investigated.
Abstract: The problem of picking up single cylindrical objects using a robot equipped with a vision system is investigated. Explanation of how the robot defines the position of objects located within the workcell is provided. Image analysis, camera calibration, and algorithm specification are also defined.
TL;DR: An algorithm for the creation of line drawings of polyhedral scenes is described, which finds the two-dimensional position of the vertices and it generates a topological description of the scene in terms of the connectiveness of the Vertices by edges.
Abstract: In this article an algorithm for the creation of line drawings of polyhedral scenes is described. It finds the two-dimensional position of the vertices and it generates a topological description of the scene in terms of the connectiveness of the vertices by edges. Application of this algorithm on a stereoscopic pair of views yields the basis for the range data acquisition. The algorithm is far from complete yet, but the results are promising.