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Automated inspection planning system for CMMs
Abstract
Coordinate measuring machines (CMMs) have been recognized as a powerful tool for inspection and measurement purposes. Maximum utilization of CMMs requires the development of an automated inspection planning system. A computer-aided inspection planning (CAIP) system leads to minimization of the total time needed for inspection process and hence the overall cost of the final product. This work introduces a computer aided inspection system that reads a B-rep solid model in SAT format as an input and produces the final CMM program in DMIS format. The system includes the following: rule-based feature recognition module that identifies and extracts the necessary inspection features from the solid model, sampling strategy module to determine the number and the location of the needed measuring points on each inspection feature, accessibility analysis module to determine the number of probe orientations that can reach the measured points without collision, finally, a clustering module to minimize the total number of probe orientations need to fully inspect the entire part. All algorithms are developed using ACIS geometric kernel and object oriented programming using C++. The results are verified on CMM.
... That is why automation of inspection becomes one of the key aspects of modern manufacturing industries. "Automation generally is defined as the process of enabling machines to follow a predetermined sequence of operations with little or no human intervention and using specialized equipment and devices that could perform and control manufacturing processes and operations" [5]. "Dimensional inspection planning is an activity to be generated specific instructions to inspect manufactured parts based on the product design" [6]. ...
... Dimensional inspection is a key activity in manufacturing industry to ensure the conformance of work piece to design specifications [5]. CMMs are recognized as powerful tool for inspection and measurement purpose [5]. ...
... Dimensional inspection is a key activity in manufacturing industry to ensure the conformance of work piece to design specifications [5]. CMMs are recognized as powerful tool for inspection and measurement purpose [5]. CMMs are numerical controlled (NC) machines and can be programmed and automated in different ways. ...
Automated inspection planning is a recent research topic demonstrating great progress in the area of inspection planning. This study introduces a computer-aided inspection planning system that reads solid CAD (a B-rep solid model in SAT, and STEP AP203 file format) models as an input and produces the final CMM program in DMIS format. The most important, complicated, time consuming, and tedious, steps while generating the inspection plan for CMMs are the selection of the features to be measured, definition of the sampling strategy, selection of the required Probe orientations, and determination of the shortest collision free path and generation of the part setups. This paper addresses rule-based feature recognition module that identifies and extracts the necessary inspection features such as: plane faces, slots, complete and incomplete cylindrical holes and shafts from the solid model. Sampling strategy module is to determine the number and the location of the needed measuring points on each inspection feature; and accessibility analysis module to determine the number of probe orientations that can reach the measured points without collision. Moreover, a clustering module to minimize the total number of probe orientations needed to fully inspect the entire part and procedural method to generate collision-free paths automatically is described. All algorithms are developed using ACIS geometric kernel and object oriented programming using C++. In all cases, verification of results through example case studies is presented.
... It has enhanced the overall process efficiency by reducing human effort which leads to less human error in major tasks such as human/manual inspection (Reem Ashima, 2021) . Different industry disciplines have applied automated inspection in various areas such as the infrastructure of bridges (Yeum & Dyke, 2015), carbon fiber composites (Christopher Sacco, 2020) (Sacco C. R., 2019) (Sacco 2018) (Meister et al., 2021), cables (Supriya, 2021) (Klinieam, 2021), machines (Hussien, 2012), oil and gas pipelines, and tanks (Shukla 2013) (Shukla 2016), material quality (Kwak et al., 2000), different products in the agricultural and food industry (Tadhg Brosnan, 2002) (Misra, et al., 2020), and vehicles (Livanos, 2018) (Schäfer, 2016). In the last decade, automated inspection used contact devices to do the inspection, requiring the part to be stationary and carefully placed. ...
Manufacturers face two opposing challenges: the escalating demand for customized products and the pressure to reduce delivery lead times. To address these expectations, manufacturers must refine their processes, to achieve highly efficient and autonomous operations. Current manufacturing equipment deployed in several facilities, while reliable and produces quality products, often lacks the ability to utilize advancements from newer technologies. Since replacing legacy equipment may be financially infeasible for many manufacturers, implementing digital transformation practices and technologies can overcome the stated deficiencies and offer cost-affordable initiatives to improve operations, increase productivity, and reduce costs. This paper explores the implementation of computer vision, as a cutting-edge, cost-effective, open-source digital transformation technology in manufacturing facilities. As a rapidly advancing technology, computer vision has the potential to transform manufacturing operations in general, and quality control in particular. The study integrates a digital twin application at the endpoint of an assembly line, effectively performing the role of a quality officer by utilizing state-of-the-art computer vision algorithms to validate end-product assembly orientation. The proposed digital twin, featuring a novel object recognition approach, efficiently classifies objects, identifies and segments errors in assembly, and schedules the paths through the data pipeline to the corresponding robot for autonomous correction. This minimizes the need for human interaction and reduces disruptions to manufacturing operations.
... Most methods focus only on coordinate measuring machines. Research work from Hussien [15] presented a computer-aided inspection system that reads as input a fixed B-rep model in SAT format and produces the final CMM program in DMIS format. In research by Gaska et al. [16] they tried to present the direction of further research, but the discussion focused mainly on five-axis systems using touch-trigger probes. ...
The article analyses and evaluates the ever-important topic of assessing geometric deviation of tolerated formations related to bases with the usage of coordinate measuring machines. The basic system for off-line simulation consists of the coordinate planes of a component’s coordinate system. At the beginning of the measurement, the coordinate system is created by the “3–2–1“alignment. Due to production deviations in real surfaces of the component, each measurement generates mutually different coordinate systems, which is well proven by the experiment on measuring with a coordinate measuring machine DEA Global Performance 12.22.10. An integral part of the article is also the quantification of geometric deviations of ideal tolerated formations related to bases, the estimate of the uncertainty of measurement arising from the placement of points in defining the base system, and the effect of such uncertainty upon the interval of satisfactory values in conformity with the STN EN ISO 14253-1 technical standard. The article also includes a proposal measure in order to ensure the reproducibility of defining the mutual position of coordinate systems.
... The tolerance information, as input by the user, is combined with stored knowledge and a set of fuzzy rules to produce optimal measurement strategies. An automated CMM inspection planning system was introduced by Hussien et al. [26] consisting of several rule-based modules for feature recognition, sampling strategy, accessibility analysis, and probe orientation clustering and minimization. The final output generates a dimensional measuring interface standard (DMIS) code for operating a CMM. ...
Capturing the strategy followed during a coordinate measuring machine (CMM) inspection planning session has been an extremely challenging issue due to the time-consuming nature of traditional methods, such as interviewing experts and technical documents data mining. This paper presents a methodology demonstrating how a motion capture-based system can facilitate direct and nonintrusive CMM operator logging for capturing planning strategies and representing in knowledge formats. With the use of recorded motion data, embedded knowledge and expertise can be captured automatically and formalized in various formats such as motion trajectory graphs, inspection plans, integrated definition (IDEF) model diagrams, and other representations. Additionally, a part program can be generated for driving a CMM to execute component measurement. The system's outputs can be used to help understand how a CMM inspection strategy is planned, as well as training aids for inexperienced operators and the rapid generation of part programs.
... In relevant work on intelligent CMMs [1][2][3], a single camera is used to identify the position and orientation of the parts and a path planning method is proposed, but not for free-form surface parts [4]. Various methods, such as the ant colony algorithm and the genetic algorithm, have been proposed for path planning in the literature [5][6][7][8][9][10]. A method of path planning for free-form surface scanning has been presented [11]. ...
With the development of the modern manufacturing industry, the free-form surface is widely used in various fields, and the automatic detection of a free-form surface is an important function of future intelligent three-coordinate measuring machines (CMMs). To improve the intelligence of CMMs, a new visual system is designed based on the characteristics of CMMs. A unified model of the free-form surface is proposed based on T-splines. A discretization method of the T-spline surface formula model is proposed. Under this discretization, the position and orientation of the workpiece would be recognized by point cloud registration. A high accuracy evaluation method is proposed between the measured point cloud and the T-spline surface formula. The experimental results demonstrate that the proposed method has the potential to realize the automatic detection of different free-form surfaces and improve the intelligence of CMMs.
... For these two cases, the threedimensional (3D) path planning from one objective to another is necessary. Early studies of CMM path planning were mainly focused on multiple features of a small part [3][4][5][6][7]. For example, Zhang et al. used the Hopfield neural network to optimize the detection path for intelligent CMMs [3]. ...
Coordinate measuring machines (CMMs) are being subjected to an increasing number of intelligent requirements due to mass manufacturing in the industry. It is important to plan the 3D measuring path for a CMM to meet the requirements of multi-objective measurements. A stable and fast three-dimensional (3D) path planning algorithm is desirable to improve the detection efficiency of a CMM. This paper establishes a 3D ant colony map for the measurement space. Then, an improved ant colony algorithm that can converge to the optimal path more rapidly than the standard ant colony algorithm is proposed. Finally, a new path re-optimization algorithm (RE-OP) and the new space collision detection algorithm are proposed. The simulation experiments show that the improved ant colony algorithm can steadily and rapidly obtain the optimal security path and can improve the detection efficiency of CMMs.
... The feature-based inspection planning in [18] uses a feature precedence tree and associated probe approach directions. Hussien et al. [19], proposed an automatic system incorporating modules for feature recognition, sampling, accessibility analysis and clustering. The probing system is modelled as an infinite line. ...
Coordinate Measuring Machines (CMM) have been widely used as a means of evaluating product quality and controlling quality manufacturing processes. Many techniques have been developed to facilitate the generation of CMM measurement plans. However, there are major gaps in the understanding of planning such strategies. This significant lack of explicitly available knowledge on how experts prepare plans and carry out measurements slows down the planning process, leading to the repetitive reinvention of new plans while preventing the automation or even semi-automation of the process. The objectives of this paper are twofold: (i) to provide a review of the existing inspection planning systems and discuss the barriers and challenges, especially from the aspect of knowledge capture and formalization; and (ii) to propose and demonstrate a novel digital engineering mixed reality paradigm which has the potential to facilitate the rapid capture of implicit inspection knowledge and explicitly represent this in a formalized way. An outline and the results of the development of an early stage prototype - which will form the foundation of a more complex system to address the aforementioned technological challenges identified in the literature survey - will be given.
... An example of the extraction of geometric information from CAD model and formation of input data is presented in [59]. An automatic inspection planning on CMMs based on B-representation of solid model in SAT format is given in [60], and at the end CMM program is generated in DMIS format. ...
This paper presents a model of prismatic parts (PPs) inspection planning on CMMs, in terms of an intelligent concept of inspection planning. The developed model is composed of Inspection Feature Construction, Sampling Strategy, Probe Accessibility Analysis, Automated Collision-Free Generation, and Probe Path Planning. In this model, the simulation of a measuring probe path is based on three algorithms: Algorithm for Measurement Points Distribution, Algorithm for Collision Avoidance, and Algorithm for Probe Path Planning. The simulation output is a measuring protocol for CMM UMM500. An experiment was performed on two PPs that have been produced for the purpose of this research. The inspection results show that all tolerances for both PPs are within the specified limits. The proposed model presents a novel approach for the automatic inspection and a basis for the development of an integrated, intelligent concept of inspection planning. The advantages of this approach imply the reduction of preparation time due to an automatic generation of a measuring protocol, a possibility for the optimisation of measuring probe path, i.e. the reduction of a time needed for the actual measurement and analysis of a workpiece, and an automatic configuration of measuring probes.
... Concepts for the automatic inspection planning are presented in [19,20]; they could serve as a basis for development and implementation of optimisation models. The state of the art in inspection planning is given in [21], whereas trends in development of the production metrology in intelligent manufacturing are shown in [22]. ...
This paper presents optimisation of a measuring probe path in inspecting the prismatic parts on a CMM. The optimisation model is based on: (i) the mathematical model that establishes an initial collision-free path presented by a set of points, and (ii) the solution of Travelling Salesman Problem (TSP) obtained with Ant Colony Optimisation (ACO). In order to solve TSP, an ACO algorithm that aims to find the shortest path of ant colony movement (i.e. the optimised path) is applied. Then, the optimised path is compared with the measuring path obtained with online programming on CMM ZEISS UMM500 and with the measuring path obtained in the CMM inspection module of Pro/ENGINEER
The paper provides an overview of the architectures for the repair and maintenance management software package for a service enterprise. As part of the research work, asset management (EAM) and service management (ITSM) methodologies were studied. Three different architectures for the designed software package are proposed, their descriptions, advantages and disadvantages are given.
Industry 4.0 represents high-level methodologies for the development of new generation manufacturing metrology systems, which are more intelligent (smart), autonomous, flexible, high-productive, and self-adaptable. One of the systems capable of responding to these challenges is a cyber-physical manufacturing metrology system (CP2MS) with techniques of artificial intelligence (AI). In general, CP2MS systems generate Big data, horizontally by integration [coordinate measuring machines (CMMs)] and vertically by control. This paper presents a cyber-physical manufacturing metrology model (CP3M) for Industry 4.0 developed by applying AI techniques such as engineering ontology (EO), ant-colony optimization (ACO), and genetic algorithms (GAs). Particularly, the CP3M presents an intelligent approach of probe configuration and setup planning for inspection of prismatic measurement parts (PMPs) on a CMM. A set of possible PMP setups and probe configurations is reduced to optimal number using developed GA-based methodology. The major novelty is the development of a new CP3M capable of responding to the requirements of an Industry 4.0 concept such as intelligent, autonomous, and productive measuring systems. As such, they respond to one smart metrology requirement within the framework of Industry 4.0, referring to the optimal number of PMPs setups and for each setup defines the configurations of probes. The main contribution of the model is productivity increase of the measuring process through the reduction of the total measurement time, as well as the elimination of errors due to the human factor through intelligent planning of probe configuration and part setup. The experiment was successfully performed using a PMP specially designed and manufactured for the purpose.
Nowadays, digitizing precise parts consisting of free-form surfaces is essential in geometrical inspections and reverse engineering. Despite the ease of use and high speed of non-contact techniques, contact methods have higher precision. However, using touch probes confront a few difficulties. Various compensation approaches that are often post-processing techniques have been introduced for contact probe errors consisting of ball-tip-radius error, stylus tilt, pre-travel, and probe lobbing. Moreover, in precise applications, achieving satisfying results is difficult and time-consuming.
The current paper proposes a computer-aided planning method by implementing a new 4-DOF parallel robot and a cost-effective linear contact probe. This parallel structure exploits three translational DOF and one rotational DOF. Furthermore, the robot is equipped with a precise turn-table. A measuring algorithm for free-form surfaces by normal-to-surface contact has been developed. Evaluating the simulation and the practical measuring results shows excellent feasibly of the method on elimination or great reduction of errors.
This chapter presents optimisation of a measuring probe path in the inspection of prismatic parts on a CMM. The optimisation model is based on the mathematical model that establishes an initial path presented by the set of points, with defined sequence of measuring probe passes without collision, and the solution of the travelling salesman problem (TSP) obtained using ant colony optimisation (ACO). A mathematical model was developed, analysed and presented in Chap. 3, so that a brief reference will be made to it in this chapter in order to relate it to the measuring path optimisation. The problem of finding the shortest measuring probe path in inspection planning of PMP on a CMM is reduced into the TSP solution. TSP is solved by using the techniques of artificial intelligence (AI) such as genetic algorithms (GA), neural networks (NN) and recently the swarm theory (ST). In order to solve TSP, ACO algorithm that aims to find the shortest path of ant colony movement (i.e. the optimised path) is applied. Then, the optimised path is compared with the measuring path obtained by online programming on CMM ZEISS UMM500 and with the measuring path obtained in the CMM module for inspection in software Pro/ENGINEER version Wildfire 4.0 (PTC Creo).
Research and development of intelligent systems for inspection planning on coordinate measuring machines (CMMs) present a precondition for the development of a new generation of technological systems and their application in a digital quality concept, which is based on a global product interoperability model [1, 2, 3, 4, 5] where CAD-CAM-CAI information is integrated within a digital platform. This approach presents a basis for virtualisation, simulation and planning inside metrological systems, particularly for the inspection of prismatic parts (PMPs) on a CMM. Research conducted within this book relates to the field of inspection planning for the metrologically complex prismatic parts on a CMM. In a broad sense, the research is directed to the development of the local and global inspection plan for prismatic parts on a CMM. In a narrow sense, it encompasses determination of inspection sequences for metrological features, determination of the number and position of measuring points, as well as the optimal measuring probe path.
This chapter presents an approach of probe configuration and setup planning for inspection of PMPs. The developed model is composed of two main parts: the analysis of PMP setups and the probe configuration for inspection on a CMM. A set of possible PMP setups and probe configurations for two types of sensors (probe star and probe head) is reduced to optimal number using a modified, current GA-based methodology. For each part setup, the optimal probe configuration and optimal point-to-point measuring path are possible to obtain. The advantage of the model is reduction of the total measurement time as well as elimination of errors due to human factor (minimising human involvement) through intelligent planning of probe configuration and part setup. This setup model can be applied not only for inspection planning on a CMM but also for the setup of prismatic parts machining on machining centres.
Computer Integrated Manufacturing (CIM) can be defined as the development of a fully automatic manufacturing system from which a complete product can be manufactured in the most efficient way. The proposed methodology focuses on an integrated system of Computer Aided Design (CAD) and Computer Aided Inspection (CAI). The integration of CAD and Computer Aided Inspection Planning (CAIP) is essential for modern industries. The proposed framework of the integrated system is composed of three main modules: Automatic Features Extraction Module, Automatic Inspection Planning Module and Coordinate Measuring Machine Module. The purposes of this paper are (a) to address the issue of integration of CAD and inspection planning in which the prismatic features of design with inspection are linked efficiently and (b) to generate and execute inspection plans through the incorporation of CAIP with CMM using DMIS code programming. Finally, a case study is presented to demonstrate and validate the integrated system.
Effective integration of the different tasks involved in CMM inspection planning is a key issue in the development of an automated and robust inspection planner. This problem has not yet been well addressed due to the lack of a formalized and integrated approach for accessibility analysis, measurement operations sequencing, and resource allocation.This paper presents a novel methodology that integrates robust analysis of the accessibility of geometric features by the CMM probe with optimum sequencing and resource allocation. The accessibility analysis is based on ray-tracing algorithms and takes into account the actual size and position of the probe. A new notion of principal clusters, which represent all possible maximum clusters of measurement points accessible with the same set of probe orientations, is introduced. Each of these clusters is associated with a specific set of probe orientations represented as a Tool/Operation matrix. The accessibility analysis is followed by establishing the optimum sequence of measurement points and optimally selecting the probes and their orientations. This methodology is believed to provide useful contributions to the development of an automated CMM inspection planner.
This article describes a method of accessibility analysis based on the geometrical study of all possible interferences between the probe and the part to be inspected. The parts considered in the analysis are rotational parts and their recognition is automatically made from a feature-based design. The probe considered is a star type, defined by adjustable parameters that allow for the adaptation to different types and sizes. The system analyses the possible collision with the machine column, touch probe and probe stylus. Apart from determining the conditions of collision, the system also calculates any collision-free positions on each surface to be probed. These positions can be used to obtain inspection paths for communication to a CMM or to a global inspection planning system. The collision conditions calculated have been checked and validated using different rotational parts.
This paper presents a general method for the accessibility
analysis of points in 3D space by straight lines such as light rays,
measurement probes and welding rods. This method can be applied to any
type of solid or surface and is not limited by continuity or
derivability constraints and may be implemented on any commercial solid
modeler with an exact representation of spheres. It is based on the
intersection of concentric spherical shells (ICSS) centred at the
analyzed point. The exact accessibility cones can be generated easily as
a limit case of the ICSS. This method has been used for the
accessibility analysis of measurement points by coordinates measuring
machines and has potential applications in fields such as machining and
robotics
The accessibility of coordinate measuring machines (CMM) and path generation in dimensional inspection are studied. The objective is to develop an algorithm which can determine all the feasible probe orientations for the inspection of a workpiece using a touch trigger probe. The feasible probe orientations ensure that when the probe tip is in contact with the workpiece there should be no collision with either the touch probe or the probe stylus. The algorithm should be able to handle internal holes and complex surfaces and be capable of extending to multiple surfaces. After solving for the probe orientations, a heuristic method determines the number of probe orientations required to inspect the workpiece. It then picks the optimal probe orientation and creates a collision-free inspection path based on the information for probe orientation.
Computer-Aided Inspection Planning (CAIP) has been a research topic for the past 25 years. Most of the CAIP systems were developed for Coordinate Measuring Machines (CMMs). The authors reviewed these CAIP systems and categorized them into two groups: tolerance-driven and geometry-based CAIP systems. Compared with CMMs, On-Machine Inspection (OMI) systems provide direct inspection in manufacturing and quality control, which is vital for automated production. Since the early 1990s, new CAIP systems have been developed for OMI systems. New technologies were developed in improving CAIP. New product data standards such as STEP and STEP-NC have been developed to provide standardized and comprehensive data models for machining and inspections. This paper systematically reviewed the recent development of these CAIP systems, new standard and technologies. A new notion of integrating the machining and inspection process planning based on the STEP-NC standard is discussed.
A feature is a local shape of a product directly related to the manufacturing process. In the computer aided process planning, information on manufacturing is essential. To get the manufacturing related information from CAD data, features should be recognized. In this paper, we thoroughly investigate the composite features, which consist of interacting simple features. The simple features in the composite feature usually have precedence relations in terms of processing sequence. The composite features are directly recognized from CAD data by our proposed projective feature recognition algorithm. Once features are recognized, they are used as input for the process planning. In the process planning, the number of set-up orientations is minimized while process sequence for the features are generated. We propose an algorithm for process planning based on the topological sorting and breadth-first search of graphs.
A method for three-axis machining of sculptured surfaces with optimal workpiece orientations (set-ups) is presented. The procedure consists of two steps: accessibility analysis and clustering of points to be machined. Feasible tool orientations along which the tool can reach the cutting locations (CLs) without colliding with the workpiece are first determined using point accessibility analysis. The cutting locations are then classified into separate groups according to their accessibility domains in order to define the workpiece set-ups. Finally, the CL points are sorted out in each group to generate tool paths. The part surface is, therefore, virtually divided into a set of subareas, and each subarea is separately machined with a defined part set-up. The main objective is to minimize the number of part set-ups, to increase the number of feasible tool orientations in each set-up and to decrease tool path discontinuity. This makes it feasible and economical to utilize three-axis machines with a table with two degrees of freedom for cutting five-axis machinable sculptured surfaces. The primary application of the introduced algorithm is in machining processes, where it can efficiently determine optimal tool orientations in surface finishing. The solution is suitable for many other manufacturing applications, such as inspection, assembly, robotics, painting and welding. Two examples including a complex centrifugal pump are used for verification.
In this paper, the probe accessibility of coordinate measuring machines (CMM) in dimensional inspection is studied. Based on the previous methods of the accessibility map, the influence of the actual configuration of the probe on the accessibility is analyzed in detail. A method, which takes the effects of the probe length and volume into account, is proposed so that the shortcomings of abstracting the probe as an infinite half-line could be overcome completely. Finally, a feasible and efficient algorithm is given.
The future success of CAD and CAM depends on the ability of these two processes to communicate with each other and with the intermediate manufacturing database. CAD-generated objects can be defined and stored as complete geometric and topologic solids. The elements of CAM, however, cannot make full use of the CAD part description because it exists in terms of low-level faces, edges and vertices or primitive volumes usually unrelated to manufacturing processes. Consequently, manufacturing planning continues to depend upon human interpretation of the part definition according to manufacturing needs. The automatic linking of CAD and CAM involves a computer interpretation of the part database to extract manufacturing-specific semantic knowledg about the part. This knowledge can enable process planning and other CAM operations to proceed automatically without human guidance or intervention.A method has been developed to automatically extract manufacturing information in the form of part features. The procedure consists of searching the part description, recognizing cavity features, extracting those features as solid volumes of material to be removed and arranging them in a feature graph, a high level data structure appropriate for manufacturing process planning. The feature recognition step uses logic programming implemented in PROLOG. Using rules of logic, definitions have been formulated to describe some common features of a part, such as holes and slots. The part is represented as a set of facts in a boundary representation format and these facts are searched to satisfy the feature rules. Multiple feature cavities can be separated into their component feature parts. This work has relevance in the areas of CAD/CAm linking, automated process planning, expert systems and, in fact, the interpretation of any 3-D data.
In this paper, the issue of inspection planning for a coordinate measuring machine (CMM) is addressed. A method is presented for the automation of the probe selection decision, with the ultimate goal of determining the set of workpiece orientations recommended for use on a CMM equipped with an indexable probe. The methodology uses a computer-aided design (CAD) model of the workpiece and a list of tolerance information as input to a feature accessibility algorithm. For each inspection feature, the algorithm generates a feasible set of probe orientations using information about potential probe/workpiece collisions, and computes an estimate of its percentage accessibility.
An expert inspection task planning system for Coordinate Measuring Machines(CMM) is developed in PROLOG. It is generative in nature and is bused on a feature-oriented computer-aided modelling system which has been developed in association with the planning system. The planning system takes into consideration the CMM characteristics, inspected part function and geometric properties, geometric tolerancing theory as well as the data extracted from the modelling system. New ideas regarding feature accessibility, feature representation in terms of the geometric elements used by CMM, inspection priority of datum features, measurement grouping according to the nature of geometric elements, checking all possible accessible features before changing a probe and/or part orientation, grouping tolerance checking tasks together based on corresponding datums, etc. and associated algorithms are proposed and implemented in this reseach. These concepts were verified and found to be feasible. Syntactic Pattern Recognition technique is used to identify a part directly from a feature-based CAD database from inspection planning point of view. The developed Feature-Oriented Modelling and Planning System, using artificial intelligence techniques, is discussed. Inspection knowledge representation and planning logic are described and illustrated with examples. Sample planning rules and inspection plan are also included. It is believed that this research can provide some useful contributions towards the development of automated inspection task planning, systems especially for coordinate measuring machines.
An overall strategy for inspection planning is discussed, and
attention is focused on local and global accessibility cones and on
algorithms for computing and clustering them. The direction-cone
clusters serve to generate a minimal set of directions for inspecting a
part. The algorithms are based primarily on the computation on Gaussian
images and Minkowski (or sweeping) operations. Applications to computer
vision and automatic machining are briefly presented
In recent years, various researchers have come up with different ways and means to integrate CAD and CAM. Automatic feature recognition from CAD solid systems highly impacts the level of integration. CAD files contain detailed geometric information of a part, which are not suitable for using in the downstream applications such as process planning. Different CAD or geometric modeling packages store the information related to the design in their own databases. Structures of these databases are different from each other. As a result no common or standard structure has been developed so far, that can be used by all CAD packages. For that reason this paper proposes an intelligent feature recognition methodology (IFRM) to develop a feature recognition system which has the ability to communicate with various CAD/CAM systems. The proposed methodology is developed for 3D prismatic parts that are created by using solid modeling package by using CSG technique as a drawing tool. The system takes a neutral file in Initial Graphics Exchange Specification (IGES) format as input and translates the information in the file to manufacturing information. The boundary (B-rep) geometrical information of the part design is then analyzed by a feature recognition program that is created specifically to extract the features from the geometrical information based on a geometric reasoning approach by using object oriented design software which is included in C++ language. A feature recognition algorithm is used to recognize different features of the part such as step, holes, etc. Finally, a sample application description for a workpiece is presented for demonstration purposes.
A hierarchical planning system using heuristics for path planning in dimensional inspection using coordinate measuring machines (CMMs) is presented. The objective is to automate the planning of a collision-free inspection path for dies and molds. The proposed system demonstrates that the inspection paths of geometrically complex parts having multiple surfaces can automatically be generated with efficiency. This is made possible by appropriate CMM abstractions, genuine 3D collision detections, and heuristic modifications of reasonably assumed default inspection paths. Automatic generation of probe angles based on a local accessibility analysis of a given surface is also presented. The collision-free inspection path can then be simulated in a CAD environment before it is carried out by the real CMM. Both simulation and experiment show excellent results of the proposed path planning strategies and demonstrate the feasibility of automatic path planning in dimensional inspection of dies and molds using CMMs.
This paper presents a methodology for determining a set of part orientations on a coordinate measuring machine (CMM), given part descriptions and tolerance information. A part frequently needs more than one orientation for inspection, and therefore it is important to determine a set of part orientations such that all tolerances under consideration can be inspected. The methodology utilizes the visibility map (VMap) to represent accessible directions from which measurements for inspecting a tolerance can be performed. The concept of VMap dimensionality is proposed to provide the basis for clustering VMaps as well as to facilitate the clustering procedure. The presented heuristic groups dimensioned VMaps into a set of disjoint VMap clusters, providing a reasonably small number of part orientations. The algorithms are implemented in C++ and tested on a SGI workstation.
This paper addresses sampling models for trimmed sculptured surfaces, and multiple patches with boundary conditions. A CAD-based
sampling system is developed and implemented in this work. The sculptured features are sampled along their isoparametric curves.
These curves are then used to re-construct the model geometry using the skinning of cross section curves. We refer to the
re-constructed model as the substitute geometry. The problem is to determine the sample curve locations such that the substitute
geometry satisfies certain geometric conditions. These are, the form error, and the continuity of the substitute geometry
across the boundaries of adjacent surfaces. Three criteria are integrated to determine the sample locations: the surface curvature
change, the substitute geometry deviation from the CAD model, and the significance of trimmed portions of the surface. A boundary
representation-based methodology for the sampling of trimmed surfaces is developed and implemented. This methodology is extended
to handle n-sided surfaces obtained through filling n-sided regions with quadrilateral surface patches, and models that may include multiple surface patches. Furthermore, a tool
to assess the sampling plans based on the continuity of the substitute geometry across boundaries of adjacent surface patches
is developed. The developed algorithms, their implementations, and case studies are presented in this paper.
This paper presents a new approach for the sampling of sculptured surfaces using continuous scanning coordinate measuring machine probe heads. This approach is based on scanning isoparametric lines on the sculptured surface. This paper addresses the issue of isoparametric line sampling. The problem is to determine the locations of the sample lines extracted from the surface CAD model. These lines are fitted to construct a substitute geometry of the surface. The accuracy of the sampling plan is characterised by the maximum deviation between the substitute geometry and the surface CAD model. Two new algorithms for sampling isoparametric lines are proposed. These are, automatic sampling, and surface curvature-based sampling. Both algorithms are constrained by the maximum number of scan lines, and the step over distance between subsequent sample lines. Automatic sampling uses the deviations between the substitute geometry, and the surface CAD model to determine the sample locations. Curvature change-based sampling uses the change in surface curvature to determine the sampling line locations. Both algorithms are compared to uniform iso-planar sampling. The algorithms, their implementation, and a case study are presented in this paper.
This paper presents an integrated artificial intelligent (IAI) system for dynamic computer-aided process planning (CAPP). The system, IAI-CAPP, integrates fuzzy logic (FL) and artificial neural networks (ANN) to perform the dynamic recognition and adaptive-learning tasks of the workpieces and process plans. Also, it adopts the idea of important (critical) feature concept for evaluating the suitability of existing process plans for incoming product designs. In addition, the technique of expert system (ES) is utilized. The system combines variant and generative CAPP and is capable of generating plans that are suitable for workpieces that either are similar to existing workpieces or new. The proposed system described has been realized on a computer prototype program. An illustrative example is also provided.
This paper addresses the issue of inspection planning, presenting a technique for automating decisions regarding probe selection and part setup for inspection on a coordinate measuring machine (CMM). Motivated by the time and expense associated with part setups, the planner is based on decreasing the number of part setups required in fully inspecting and verifying defined dimensional and geometrical constraints. Successfully implemented and tested, the feature accessibility algorithm utilizes a computer-aided design (CAD) model of the workpiece and a list of tolerance information in applying a geometric projection technique to define the accessible region(s) of each inspection feature. A heuristic technique is implemented to analyse accessibility results and probe selections in defining the set of workpiece orientations recommended for full inspection and verification of the defined dimensions and tolerances.
Computer-controlled dimensional inspection is typically performed
with coordinate measuring machines (CMMs), which are very precise
Cartesian robots that use touch probes to measure the coordinates of
points on a workpiece's surfaces. Automatic planning and programming of
inspection tasks with a CMM involve spatial reasoning, to determine how
to orient the part on the CMM, which probes to use, how to orient the
probes, and so on. This paper introduces the notions of accessibility
and approachability, which are important for inspection planning, and
describes two sets of implemented algorithms for computing accessibility
information. One of these sets of algorithms performs exact computations
on polyhedral objects and is relatively slow, whereas the other uses
discrete approximations and achieves high speed by exploiting standard
computer graphics hardware. The discretized algorithm has been tested on
real-world parts, and is sufficiently fast for industrial applications
Computer Aided Process Planning Using Feature Recognition For Milled Parts, M.Sc. Thesis, Military Technical College
- A M Fikry
Industrial Coordinate Metrology -Ten years of innovations
- H Neumann
H. J Neumann, Industrial Coordinate Metrology -Ten years of innovations, Carl Zeiss international Publications. 2000.