Improving the sequence of robotic tasks with freedom of execution
06 Nov 2014-pp 4503-4510
TL;DR: This paper proposes a method that is able to automatically improve the given sequence of robotic tasks that allow for a certain freedom in the position of the starting point along the curve, the orientation of the end-effector and the robot configuration.
Abstract: An industrial robot’s workflow typically consists of a set of tasks that have to be repeated multiple times. A task could be, for example, welding a seam or cutting a hole. The efficiency with which the robot performs the sequence of tasks is an important factor in most production domains. The more often a set of tasks can be performed by a robot the more advantages it provides to the company. In most practical scenarios, the majority of tasks have a certain freedom of execution. For example, closed-contour welding task can often be started and finished at any point of the curve. Also the exact orientation of the welding torch is not fixed, but may be in a certain range, e.g., between 85◦ and 95◦. Currently, these degrees of freedom are used to manually generate robot trajectories. However, their quality highly depends on skills and experience of the robot programmer. In this paper we propose a method that is able to automatically improve the given sequence of robotic tasks by adding certain freedom to (i) the position of the starting point along the curve, (ii) the orientation of the end-effector and (iii) the robot configuration. The proposed approach does not depend on the production domain and could be combined with any algorithm for constructing the initial task sequence. We evaluate the algorithm on a realistic case study and show that it could significantly improve the production time on the test instances from the cutting-deburring domain.
Citations
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Journal Article•
351 citations
TL;DR: A review of the literature on generating cutting paths for laser cutting machines is presented in this article, where a former classification method is updated to include all types of cutting path problems and a comprehensive review of solution methods and related applications is presented.
Abstract: This paper presents a review of the literature on generating cutting paths for laser cutting machines. Firstly, the cutting path problem is defined including all relevant technical side constraints which exist plentifully in laser cutting. Secondly, a former classification method is updated to include all types of cutting path problems. Thirdly, a comprehensive review of solution methods and related applications is presented. Throughout the literature review, trends in research in cutting path generation and interesting areas for future research are identified.
59 citations
TL;DR: This paper proposes a fuzzy PID control method for deburring industrial robots that relates to the trajectory and joint angular parameters of the end-effector on a robot through an adaptive fuzzy PID controller that updates online at each sampling time.
Abstract: This paper proposes a fuzzy PID control method for deburring industrial robots. The adaptive fuzzy PID controller relates to the trajectory and joint angular parameters of the end-effector on a robot. The PID controller parameters update online at each sampling time to guarantee trajectory accuracy of the end-effector. The simulation of the fuzzy PID control is provided based on the 6-DOF deburring industrial robot. Experimental results demonstrate the efficiency of the fuzzy PID control method.
22 citations
Cites background from "Improving the sequence of robotic t..."
...The end-effector orientation and position freedom, as well as the robot configuration, greatly influences the cost of supporting movement [14]....
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01 Sep 2014
TL;DR: This paper presents the trajectory optimization problem where the end-effector path is allowed to have a certain deviation, referred to as relaxed path, and constructs the minimal-cost robot trajectory.
Abstract: In this paper we consider the trajectory optimization problem for the effective tasks performed by industrial robots, e.g., welding, cutting or camera inspection. The distinctive feature of such tasks is that a robot has to follow a certain end-effector path with its motion law. For example, welding a line with a certain velocity has an even influence on the surface. The end-effector path and its motion law depend on the industrial process requirements. They are calculated without considering robot kinematics, hence, are often “awkward” for the robot execution, e.g., cause high jerks in the robot's joints. In this paper we present the trajectory optimization problem where the end-effector path is allowed to have a certain deviation. Such path is referred to as relaxed path. The goal of the paper is to make use of this freedom and construct the minimal-cost robot trajectory. To demonstrate the potential of the problem, jerk of the robot joint trajectory was minimized.
11 citations
Cites background from "Improving the sequence of robotic t..."
...For example, laser-welding can be performed with a set of possible tool orientations (Kovács, 2013) or cutting can be performed with a set of possible tool positions and orientations (Alatartsev and Ortmeier, 2014)....
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...For example, laser-welding can be performed with a set of possible tool orientations (Kovács, 2013) or cutting can be performed with a set of possible tool positions and orientations (Alatartsev and Ortmeier, 2014)....
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01 Sep 2015
TL;DR: This paper proposes a new approach for analyzing CPS configurations for manipulation tasks that applies a graph-based model to define the individual failures of each component and the geometrical links in between.
Abstract: The concepts of “Industry 4.0” are founded on Cyber-Physical Systems (CPS) that interact flexibly with each other. The system is no longer an individual robot equipped with a predefined set of sensors, drives and manipulators. Furthermore, it represents a task-specific selection of all available CPS in a certain area. This adaptive composition provides flexible handling of varying environmental conditions and stabilizes the perception quality related to the current task requests. But the permanent adaptation includes a number of challenging tasks - the selection and adjustment of the involved CPS has to be done on run-time now. In this paper we propose a new approach for analyzing CPS configurations for manipulation tasks. If a mobile robot has to handle an object, the algorithm explores all available actuators and sensors. The proposed concept applies a graph-based model to define the individual failures of each component and the geometrical links in between. Based on this representation, all suitable combinations are determined, the expected failure level is calculated and compared in relation to the requested handling precision.
10 citations
Cites background from "Improving the sequence of robotic t..."
...…aggregation of the context parameters, 2) comparison between requested and provided capabilities 3) decision about the applicability of a certain pickup and setting In case of a negative result the engineer probably integrates additional sensors, refines the control or reconfigures the manipulator....
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References
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01 Jan 2006
TL;DR: This coherent and comprehensive book unifies material from several sources, including robotics, control theory, artificial intelligence, and algorithms, into planning under differential constraints that arise when automating the motions of virtually any mechanical system.
Abstract: Planning algorithms are impacting technical disciplines and industries around the world, including robotics, computer-aided design, manufacturing, computer graphics, aerospace applications, drug design, and protein folding. This coherent and comprehensive book unifies material from several sources, including robotics, control theory, artificial intelligence, and algorithms. The treatment is centered on robot motion planning but integrates material on planning in discrete spaces. A major part of the book is devoted to planning under uncertainty, including decision theory, Markov decision processes, and information spaces, which are the “configuration spaces” of all sensor-based planning problems. The last part of the book delves into planning under differential constraints that arise when automating the motions of virtually any mechanical system. Developed from courses taught by the author, the book is intended for students, engineers, and researchers in robotics, artificial intelligence, and control theory as well as computer graphics, algorithms, and computational biology.
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"Improving the sequence of robotic t..." refers background in this paper
...Often a point in this space is described with homogeneous transformation matrix [8]....
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01 Jan 1986
TL;DR: This chapter discusses Jacobians: Velocities and Static Forces, Robot Programming Languages and Systems, and Manipulator Dynamics, which focuses on the role of Jacobians in the control of Manipulators.
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5,992 citations
TL;DR: The phrase "direct search" is used to describe sequential examination of trial solutions involving comparison of each trial solution with the "best" obtained up to that time together with a strategy for determining (as a function of earlier results) what the next trial solution will be.
Abstract: In dealing with numerical problems for which classical methods of solution are unfeasible, many people have tried various procedures of searching for an answer on a computer. Our efforts in this direction have produced procedures which seem to have had (for us and for others who have used them) more success than has been achieved elsewhere, so that we have been encouraged to publish this report of our studies. We use the phrase \"direct search\" to describe sequential examination of trial solutions involving comparison of each trial solution with the \"best\" obtained up to that time together with a strategy for determining (as a function of earlier results) what the next trial solution will be. The phrase implies our preference, based on experience, for straightforward search strategies which employ no techniques of classical analysis except where there is a demonstrable advantage in doing so. We have found it worthwhile to study direct search methods for the following reasons: (a) They have provided solutions to some problems, of importance to us, which had been unsuccessfully attacked by classical methods. (Examples are given below.) (b) They promise to provide faster solutions for some problems that are solvable by classical methods. (For example, a method for solving systems of linear equations, proposed in Section 5, seems to take an amount of time that is proportional only to the first power of the number of equations.) (c) They are well adapted to use on electronic computers, since they tend to use repeated identical arithmetic operations with a simple logic. Classical methods, developed for human use, often stress minimization of arithmetic by increased sophistication of logic, a goal which may not be desirable when a computer is to be used. (d) They provide an approximate solution, improving all the while, at all stages of the calculation. This feature can be important when a tentative solution is needed before the calculations are completed. (e) They require (or permit) different kinds of assumptions about the functions involved in various problems, and thus suggest new classifications of functions which may repay study. Direct search is described roughly in Section 2, and explained heuristically in Section 3. Section 4 describes a kind of strategy. Sections 5 and 6 describe
4,184 citations
"Improving the sequence of robotic t..." refers methods in this paper
...We applied the Pattern search [19] for optimization on the Stages 1 and 2....
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24 Apr 2000
TL;DR: A simple and efficient randomized algorithm is presented for solving single-query path planning problems in high-dimensional configuration spaces by incrementally building two rapidly-exploring random trees rooted at the start and the goal configurations.
Abstract: A simple and efficient randomized algorithm is presented for solving single-query path planning problems in high-dimensional configuration spaces. The method works by incrementally building two rapidly-exploring random trees (RRTs) rooted at the start and the goal configurations. The trees each explore space around them and also advance towards each other through, the use of a simple greedy heuristic. Although originally designed to plan motions for a human arm (modeled as a 7-DOF kinematic chain) for the automatic graphic animation of collision-free grasping and manipulation tasks, the algorithm has been successfully applied to a variety of path planning problems. Computed examples include generating collision-free motions for rigid objects in 2D and 3D, and collision-free manipulation motions for a 6-DOF PUMA arm in a 3D workspace. Some basic theoretical analysis is also presented.
3,102 citations
"Improving the sequence of robotic t..." refers background in this paper
...Often they do not have constraints on the execution and are programmed manually or calculated with collision-free path planners [3]....
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