Robotic path compensation training method for optimizing face milling operations based on non-contact CMM techniques

Currently, the use of industrial robots in the machining of large components in metallic materials of significant hardness is proliferating. The low rigidity of industrial robots is still the main conditioning for their use in machining applications, where the forces developed in the process cause significant deviations on the cutting tool path. Although there are already methodologies that facilitate the pose study of the robot mechanical behaviour, predicting deviation values of the cutting tool path and facilitating the selection of process variables, robotic cell users still request new methods able to allow them to optimize the use of these production systems. On the other hand, non-contact measurement technologies have burst into many fields of knowledge, their use is becoming consolidated, and they allow the digitization of complex surfaces. This research presents the development of a new method of robotic machining trajectory compensation that allows optimizing the manufacture of flat surfaces using an industrial anthropomorphic robot. The new training method determines the actual deviations of the cutting tool after the machining process, and checks if these are within the admissible range of flatness error. This method is a novel iterative technique that incorporates the algorithm that uses the measured deviations and a reduction factor fr to calculate the offset that modifies the coordinate value of the programmed path points outside the admissible range and generates a new machining path to be tested. The method has been tested on a pre-industrial scale for aluminium machining, and the algorithm has carried out two iterations to generate a compensated robotic milling path within a flatness tolerance range of 300 µm, improving the error deviation by 37% comparing to the initial path.     

A Robotic-Driven Disassembly Sequence Generator for End-Of-Life Electronic Products

In this study, we propose an intelligent automated disassembly cell for online (real time) selective disassembly. The cell is composed of an industrial robotic manipulator, a camera, range sensing and component segmentation visual algorithms. The cell prototype allows for robotic sensory-driven disassembly under uncertainty. An online genetic algorithm model for selective disassembly is also proposed for optimal and near/optimal disassembly sequencing.     

Adaptive Partial Shortcuts: Path Optimization for Industrial Robotics

The quality of a path generated from an automated motion planning algorithm is of considerable importance, particularly when used in a real world robotic application. In this work a new path optimization algorithm, called the Adaptive Partial Shortcut algorithm, is presented. This algorithm optimizes paths as a post process to motion planning, and is designed specifically for use on industrial manipulators. The algorithm optimizes a robot’s degrees of freedom independently allowing it to produce manipulator paths of particularly high quality. This new algorithm utilizes an adaptive method of selecting the degree of freedom to optimize at each iteration, giving it a high level of efficiency. Tests conducted show the effectiveness of the algorithm; over a range of different test paths, the adaptive algorithm was able to generate solutions with a 60 % reduction in collision checks compared to the original partial shortcut approach.     

Automated synthesis of hybrid Petri net models for robotic cells in the aircraft industry

The use of robots in the aircraft structural assembly is a challenge. The presence of human operators, auxiliary systems and industrial robots makes hybrid the dynamic behavior of a robotic cell in this context. Here, the focus is on the automated synthesis of a model for the sequencing of the activities of a robotic cell in the aircraft industry. The cell model is obtained from a simple specification of resources and tasks, considered the main cell components, running the algorithm presented in this paper. The effectiveness of the model is shown using a case study defined by the ongoing European project LOCOMACHS (LOw COst Manufacturing and Assembly of Composite and Hybrid Structures, http://www.locomachs.eu/).     

Merging the autoview image processing language with prolog

A new computer language, called provision, is defined. It combines features of both prolog (for artificial intelligence) and autoview (for image processing). Predicates for image processing, controlling cameras, illumination sources, optics, a video multiplexor and simple robotic devices are all integrated with PROLOG2, an extension of standard core prolog. The result is a powerful medium for expressing a wide range of algorithms for the visual control of robots and advanced industrial inspection. Several provision applications (i.e. ‘programs’) are presented.     

Mutual information-enhanced digital twin promotes vision-guided robotic grasping

Vision-guided learning for autonomous robotic manipulations is a wide-ranging and high-impact topic in the context of smart manufacturing. Most learning strategies are object-centered or prior information-dependent, which likely lead to the problems of generalization across objects or scenes. To alleviate this, this work presented an embodiment decision-making method by the marriage between the digital twin epistemology and information-theoretic approach. The initial insight was that the mutual information generated in the interactions between the available vision models and real-world perceptions could decrease the uncertainty of sensing-action processes. Further, the real-time interactive information gains and visual templates constitute the digital twin through bidirectional data flowing and real-time optimization. As a demonstration of concept, on the conveyor-based and vision-guided robotic grasping platform, the robotic grasping experiments of freely placed and moving parts were performed. Experimental results indicated that the autonomous and real-time optimization of the conveyor-based and vision-guided robotic grasping system happens and the adaptability to the real-world changes had been clearly increased. This research suggested that the representation and dynamic capture of the complex interactions between both sides of cyber-physical system could generate new possibilities to the evolution of decision-making paradigm in more complex industrial processes.     

Flexible robotic demanufacturing using real time tool path generation

The need for new demanufacturing technologies exists due to a growing population of end of life electronic products. The demanufacturing method presented in this work is unique from disassembly because destructive methods are employed; thus, eliminating the need to account for precedence relationships. Furthermore, the new demanufacturing method employs cutting operations but differs from traditional machining operations due to the degree of flexibility required. To address this very high scale flexibility, a unique prototype flexible demanufacturing work cell has been established. Unique contributions of this flexible demanufacturing method include a new system model that utilizes a product surface model and a robot tool position model to actively generate real time tool paths. The model uses manifolds to reduce the tool path generation function to navigation of the surface manifold. Tool path generation occurs in three stages: machining operation sequencing, active tool path generation and active product avoidance. A case study of the demanufacture of mobile phones is presented to illustrate the flexible robotic demanufacturing operation. The case study shows that a new flexible robotic demanufacturing process has been achieved that requires no predetermined information on the product surface geometry.     

An architecture for universal construction via modular robotic components

A set of modular components is presented for use in reconfigurable robotic construction systems. The set includes passive and active components. The passive components can be formed into static structures and adaptable grids carrying electrical power and signals. Passive and active components can be combined into general purpose mobile manipulators which are able to augment and reconfigure the grid, construct new manipulators, and potentially perform general purpose fabrication tasks such as additive manufacturing. The components themselves are designed for low-cost, simple fabrication methods and could potentially be fabricated by constructors made of the same components. This work represents a step toward a Cyclic Fabrication System, a network of materials, tools, and manufacturing processes that can produce all of its constituent components. These and similar systems have been proposed for a wide range of far-term applications, including space-based manufacturing, construction of large-scale industrial facilities, and also for driving development of low-cost 3D printing machines.     

Merging the autoview image processing language with prolog

A new computer language, called provision, is defined. It combines features of both prolog (for artificial intelligence) and autoview (for image processing). Predicates for image processing, controlling cameras, illumination sources, optics, a video multiplexor and simple robotic devices are all integrated with PROLOG2, an extension of standard core prolog. The result is a powerful medium for expressing a wide range of algorithms for the visual control of robots and advanced industrial inspection. Several provision applications (i.e. ‘programs’) are presented.     

The state of the art of testing standards for integrated robotic systems

Technology standards facilitate the transparency in market and the supplies of products with good quality. For manufacturers, standards make it possible to reduce the costs by mass production, and enhance system adaptabilities through integrating system modules with the standardized interfaces. However, International standards on industrial robots such as ISO-9283 were developed in 1998, and they have not updated since then. Due to every-increasing applications of robots in complex systems, there is an emerging need to advance existing standards on robots for a broader scope of system components and system integration. This paper gives an introduction of the endeavors by National Institute of Standards and Technology (NIST); especially, it overviews the recent progresses on the standardized tests of robotic systems and components. The presented work aims to identify the limitations of existing industrial standards and clarify the trend of technology standardizations for industrial robotic systems.     

An evaluation of machine guarding techniques for robot guarding

An increasing number of problems caused by the use of industrial robots should be expected due to the dramatically increasing population of robots today. In this paper, machine guarding functions and techniques are reviewed. The possibilities of transferring the concepts of machine guarding to robotic systems are then analyzed. The analysis shows that most of the guarding techniques are still applicable to industrial robots with modifications to accommodate differences. A set of guidelines for installing safeguarding devices is also presented. Research is need in the areas of guarding techniques for robotic cells, new sensor development, and sensor reliability, fusion, and coordination problems.     

A manufacturing hand

In unmanned Flexible Manufacturing Cells, robots can be used for loading machines, inspection activities, and assembly operations. What kind of robotic end-effector should be built for such tasks? The human hand has evolved to be a general purpose manipulator that adapts to the richness of our daily lives but, in doing so, it is not particularly suited to manufacturing operations. Here, we rely heavily on special tools, fixtures, and protective layers. This paper describes the initial development of a hand specifically for manufacturing work. This has involved the manufacture of an instrumented wrist with an adjustable remote center of compliance, and the design of fingers for gripping. Object shapes have also been analysed in order to provide for a stable static grip. Importantly, these studies of the physical aspects of prehension have been matched to tasks. The research has considered a range of industrial operations and specified the level of end-effector control needed. This work is leading to some design guides for robotic end-effectors which, it is hoped, will be of use to industrial designers.     

PC-based hierarchical manufacturing cell control

Robots in the industrial factory plant build the backbone for CIM, which is outlined to be the factory automation strategy of the future. In this paper a hierarchical manufacturing cell control system for robotic work cells is described. This approach is based on low-cost personal computer hardware and consists of two different control systems, one for the robot control tasks and another for the work cell control tasks. The underlying concept is based on a strategic architectural model for hierarchical manufacturing control, where it focuses on the process sequence coordination and the process control in the bottom hierarchical layers.     

Autonomous robotic inspection and manipulation using multisensorfeedback

A six-degree-of-freedom industrial robot to which was added a number of sensors-vision, range, sound, proximity, force/torque, and touch-to enhance its inspection and manipulation capabilities is described. The work falls under the scope of partial autonomy. In teleoperation mode, the human operator prepares the robotic system to perform the desired task. Using its sensory cues, the system maps the workspace and performs its operations in a fully autonomous mode. Finally, the system reports back to the human operator on the success or failure of the task and resumes its teleoperation mode. The feasibility of realistic autonomous robotic inspection and manipulation tasks using multisensory information cues is demonstrated. The focus is on the estimation of the three-dimensional position and orientation of the task panel and the use of other nonvision sensors for valve manipulation. The experiment illustrates the need for multisensory information to accomplish complex, autonomous robotic inspection and manipulation tasks     

Economic analysis of robotic operations: A case study of a thermal spraying robot

There is growing interest in the industrial applications of computer-integrated manufacturing (CIM) and robotic technology. The economic analysis methods which are currently available to assess the cost effectiveness of robotic systems are, however, limited. This paper presents a methodology to address this issue. To demonstrate the methodology, a case-study is presented which uses a thermal spraying robot in a rapid tool manufacturing system. The interdependencies between tolerance, robot accuracy, and the probability of a successful spraying operation are demonstrated. The economic effects of using robots in the spraying process are analyzed. Analytical models are developed to estimate the productivity of components without any defects and the improvement in tool life attributable to robotic spraying. The economic analysis method presented in the paper is also applicable to other operations such as robotic assembly and robotic welding.     

A force–impedance controlled industrial robot using an active robotic auxiliary device

A strategy to improve the performance of current commercial industrial robots is presented in this paper. This strategy involves cooperation of two robotic manipulators: the robotic controlled impedance device (RCID) and a commercial industrial robot. The RCID is a small six degrees-of-freedom (DOF) high bandwidth force–impedance controlled parallel manipulator, developed at the School of Engineering of the University of Porto (Portugal). The RCID works attached in series with a position controlled commercial industrial robot. Combination of the two manipulators behaves as a single manipulator having the impedance and force control dynamic performance of the RCID, as well as the workspace and trajectory tracking bandwidth of the industrial robot. Force–impedance control of the RCID, and experimental results on typical tasks that involve end-effector contact with uncertain environments of unknown stiffness are presented.     

A Pseudo-Distance Algorithm for Collision Detection of Manipulators Using Convex-Plane-Polygons-based Representation

Robots have become indispensable parts for the industrial automated workshop. The distance calculation between the industrial robot and obstacles is a fundamental problem for the robotic collision-free motion control. But existing methods for this problem have the disadvantage that the accuracy and execution efficiency cannot be guaranteed at the same time. In this paper, a pseudo-distance algorithm is presented based on the convex-plane-polygons-based representation to solve this problem. In this algorithm, convex plane polygons (CPPs) and cylinders are utilized to represent obstacles and the manipulator, respectively. The spatial relationship between each CPP and each cylinder is discussed through defining condition parameters, and is divided into six conditions including three special conditions when the contact happens, and the other three conditions when there exists a certain distance between the CPP and the cylinder. The distance is modelled under different relations based on the theory of mathematics and geometry. The pseudo distance is determined through selecting the smallest value from distances between CPPs and cylinders. The numerical experiment is performed based on the proposed and two previous algorithms to estimate the shortest distance between an industrial robot and a groove-shape obstacle. And an application example is performed to show the significance of this work on the robotic motion control. Results indicate that the proposed algorithm is more efficient than previous algorithms under a certain precision requirement, and can be effectively applied in the robotic motion control.     

The NTUA snake: Design,planar kinematics,and motion planning

A new kind of robotic mechanism is proposed to be used for inspection tasks in complex setups of industrial plants. We propose a multiarticulated snake‐like mobile robot, with a body consisting of repeating modules, capable of both efficiently moving and reaching points inside complicated or unstructured areas, where human personnel cannot reach or work properly. An analysis of the basic design along with most of the component specifications is presented. This mechanical system is subject to nonholonomic constraints. The kinematic model for motion on‐plane of the mobile robot is derived by taking into consideration these constraints. The nonholonomic motion planning is partially solved by converting the multiple‐input system to a multiple‐chain, single‐generator chained form via state feedback and a coordinate transformation. Stabilization and trajectory tracking issues are also considered. We also consider the general case of the n‐trailer (or n‐module) robotic snake. Simulation results are provided for various test cases. ©1999 John Wiley & Sons, Inc.     

Autonomous weld seam identification and localisation using eye-in-hand stereo vision for robotic arc welding

One of the main difficulties in using robotic welding in low to medium volume manufacturing or repair work is the time taken to programme the robot to weld a new part. It is often cheaper and more efficient to weld the parts manually. This paper presents a method for the automatic identification and location of welding seams for robotic welding using computer vision. The use of computer vision in welding faces some difficult challenges such as poor contrast, textureless images, reflections and imperfections on the surface of the steel such as scratches. The methods developed in the paper enables the robust identification of narrow weld seams for ferrous materials combined with reliable image matching and triangulation through the use of 2D homography. The proposed algorithms are validated through experiments using an industrial welding robot in a workshop environment. The results show that this method can provide a 3D Cartesian accuracy of within ±1 mm which is acceptable in most robotic arc welding applications.     

Fuzzy multi-criteria evaluation of industrial robotic systems

Industrial robots have been increasingly used by many manufacturing firms in different industries. While the number of robot manufacturers is also increasing with many alternative ranges of robots, potential end-users are faced with many options in both technical and economical factors in the evaluation of the industrial robotic systems. Industrial robotic system selection is a complex problem which many qualitative attributes must be considered. These kinds of attributes make the evaluation process hard and vague. Hierarchical structure is a good approach to describe a complicated system. This paper proposes a fuzzy hierarchical TOPSIS model for the multi-criteria evaluation of the industrial robotic systems. An application is presented with some sensitivity analyses by changing the critical parameters.