The authors discuss the difficulty in providing easy and transparent access to CNC controls. The major issues involve the integration of process control and the extension of the control to include additional user provided hardware and software. Specific attention is focused upon a modular architecture developed by the authors at the University of British Columbia over the past ten years.
Current machine control operating environments rely heavily upon G codes to specify the desired machine behavior. G codes provide a sequential non-preemptive execution semantics that, together with the operating environment, allow for precise control of the machine. However, G codes do not allow for the type of reactive behavior specification required in the next generation of open architecture manufacturing system and propose the semantics for a language that meets those requirements.
An algorithm suitable for triangulating 3D data points, produced by a machine vision system or coordinate measuring machine (CMM), is described. The algorithm is suitable for processing the data collected from objects composed of free form surface patches. The data is produced by a 3D machine vision system integrated into a computer numerically controlled CMM. The software can model very large 3D data sets, termed cloud data, using a unified, non-redundant triangular mesh. This is accomplished from the 3D data points in two steps. Firstly, an initial data thinning is performed, to reduce the copious data set size, employing 3D spatial filtering. Secondary, the triangulation commences, utilizing a set of heuristic rules, from a user defined seed point. The triangulation algorithm interrogates the local geometric and topological information inherent in the cloud data points. The spatial filtering parameters are extracted from the cloud data set, by a series of local surface patches, and the required spatial error between the final triangulation and the cloud data. Case studies are presented that illustrate the efficacy of the technique for rapidly constructing a geometric model from 3D digitized data.
The authors describe the integration of process planning and remote monitoring within an existing open architecture CNC. The process planning system described is designed to allow dynamic replanning of the process as well as the updating of technological information concerning tools and workpiece. The monitoring system is designed to drive a virtual machine tool at a remote location.
The advance of coordinate measurement technique is caused by the fact that by the introduction of CAD/CAM and CAQ systems connected to the technological process planning the need arises for quick, precise and automated inspection methods of form surfaces. In consequence of the advance of flexible manufacturing systems and CAD/CAM systems as well as the propagation of 3D measuring machines, there is increasing demand for the automated geometrical qualification of helicoid surfaces. The geometrical inspections and qualification of the most widely used cylindrical and conical helicoid surfaces - having constant pitch - on 3D coordinate measuring machine are an indispensable condition of the automated production of possible version of helicoid surfaces. Regarding the fact that the parameters affecting the above mentioned industrial features are closely connected with each other, the engineers who design the construction and plan the production need a high level special knowledge. The same is required from the specialists who deal with the production and assembly, because a significant percent of desired industrial features can be insured during the production and assembly. Within the conception design first of all we will deal with the geometrical characteristics, which influence the formation of the bearing pattern. The bearing pattern fundamentally determines the working characteristics. Furthermore, we will discuss the simulation which is a model of the operation.
This report deals with the analysis and the design of a conventional machining system by means of mathematical modeling of the machining process. The paper considers the machining process as a dynamic interaction between the cutting tool and workpiece in space and time that additionally involves the dynamic properties of the machine tool mechanical subsystem, the cutting motions. An ideal machining system provides an accurately controlled tool path. However, machining experience has shown that the geometric qualities of the machined part are not only defined by the uniformity of the too path, but are also influenced by the dynamics of the machine tool and cutting process and by the external and internal disturbances. Developed herein, is a systematic approach tying together the four main factors associated with the dynamic processes that play an important role during machining and influence the quality of the machined workpiece. These factors are (a) the kinematic/dynamic disturbances within the cutting/feed motion subsystem, (b) the dynamics of the machine tool mechanical subsystem, (c) the tool-workpiece interaction as a dynamic process, and (d) the forming of the workpiece surface as a dynamic surface as a dynamic process. The generalized mathematical model of the machining process is developed based on the dynamic relationships between those above-mentioned aspects of the process. The approach performs the dynamic analysis of a machining process for diagnostics, control, and process optimization purposes.
Worm-, hypoid-, spiroid-, toroid- and crown wheel gear drives can be mentioned as gears with offset of axes. It is well known that eh efficiency of gears with offset of axes are less favorable than gears with parallel axes. The reason is the stretch difference between the elements, the gears of the drive, which has an additional effect on the load of carrying bearing. The loss following the friction between tooth-surfaces and the corresponding drive efficiency has discussed theoretically with acceptable accuracy just in case of work gears. The measured values gained in laboratories and factories show quite high spread figures relating them either to one another or to the calculated results as expressed above. That is why it seem to be logical to separate the tribological tests - the results of which we are trying to summon up in the Coulomb factor - from the stretch rate appearing between the tooth surfaces. This stretch-rate depends on the geometrical structure of the space of meshing and can be expressed in loss factor not attached to any dimension. This loss factor can be defined either geometrically or kinematically taking the tangential speed into consideration. Knowing the value of Cv loss factor at any point of the space of meshing can be expressed quite simply.
Multiple off-the-shelf cameras can be configured to simultaneously provide a large variety of part features that are impossible to capture with a single CCD camera or range scanner. One unsolved problem is using several cameras for passive shape recognition is that of multi-view registration. Registration is the process of associating the feature vectors extracted from the image captured by one camera view with that from another view. This paper describes an unsupervised clustering algorithm used to associate redundant and complementary features extracted from different views of a 3D object for part identification and inspection. The unsupervised learning algorithm ensures that 'similar' feature vectors will be assigned to cluster units that lie in close spatial proximity in a 3D feature map. The technique reduces the dimensionality of the input by exploiting hidden redundancies in the training data. During the inspection phase, novel features activate a number of cluster nits that have weights similar to the applied training data. During the inspection phase, novel features activate a number of cluster units that have weights similar to the applied training input. If the sum- of-square error between the input and weights of the cluster unit with the strongest response is greater than a predefined tolerance, then the part is rejected. A simulation study is presented to illustrate how the proposed multi-sensor fusion technique can be applied to identifying parts for inspection.
A fiber optic sensor system is described for non-contact measurement of surface texture. The sensor employs a fiber optic guide and lens arrangement that forms an interferometric cavity between the lens front face and the surface. Changes in the surface topography are manifested as phase changes between the light reflected from the surface and the front face of the lens. An electronic control and data acquisition system converts the phase change into a voltage signal proportional to surface topography. The sensor performance is evaluated against stylus profilometer result and comparison of the amplitude parameter, Ra, shows good agreement.
Recently the main purpose of the companies is to product their products in the highest quality corresponding to the market demand. Instead of the inspection of the products more and more the increased inspection of the production process and devices is required for providing the desired quality. The reliability and the effectiveness of the measurings performed during inspections can not be provided without measuring data collecting and feedback to the manufacturing process, its rapid evaluation and documentation. These activities require advanced measuring technique devices. This article shows devices and application examples from the are of the latest measuring technique development.
Biological visual information processing can be divided into two processing levels: low level and high level.Low level visual processing includes several elementary operations allowing a reduction of the large amount of data present in a scene and from this recovering useful information at a higher level. An important operation is edge detection, which consists of image segmentation and consequent higher level processing for pattern classification and object recognition. Approaches to the edge detection problem vary from histogram based thresholding to biologically motivated gradient operators and discriminant functions. They provide edge detection of given images with various fidelities and at different computational expenses.
With this publication a high-processing non-contact distance sensor for heavy accessible movable components in industrial machines and engines is presented. A lot of systems exist for distance measurement. Most of them have a rectangular casing and it is not possible to use them in every industrial environment. Another disadvantage is the slow signal processing which makes it impossible to use them for the signal processing of high-speed motions. The common CCD sensors can only run with ca 5kHz measuring rate. Additional the relation of resolution and measurement range is too low for the actual used triangulation sensor. Furthermore, this paper gives some detailed information about the accuracy, resolution and the measuring rate of the new sensor.
Laserwelding is a most important technique in automatic production lines for high numbers of production units. Visualizing the process accelerates the production, enables controlling the process parameters and reduces waste. We present latest results of an online visualization system in this industrial process. Sensor of different sensitivity, combined with optical materials, new in this field, give information to signal processors for mathematical evaluation. Computed result give immediate response to the system. We used the latest digital signal processing technique to cover the need for quick response within a few microseconds. Thus the system can react and for example exceed the laser power or add material to avoid pores.
Simultaneous to the rapid evolution of laser welding, with increased improvements concerning reliability and effectiveness, the need for quality control has grown. The development of system which monitor process quality online, and detect faulty welding results immediately after the defect occurs, has proven to be useful. Such process monitoring systems are usually based on the evaluation of the radiation emitted from the welding spot. This procedure offers a simple way to rate the welding quality, and to detect typical errors. However, it is not possible to recognize the nature of the fault with these single-sensor- setups. To obtain more specific information about the process, additional sensoring is necessary. Within this paper, an approach with IR signal acquisition is described, and correlations are presented. It is shown that the supplementary information coming from a 2D thermo-image allows the identification of typical welding defects. Subsequently, a method for an optimized and practical evaluation strategy using a 1D, line-shaped IR-acquisition is introduced.
With this publication a coil identification algorithm inside a high precision triangulation sensor for residual shorts measurements of cooling material is presented. The sensor is a stand-alone system. A digital signal processor, a field programmable gate array and a microcontroller collect and process the data of the linear CCD-sensors. The basic element of the sensor is a symmetrical arrangement of two laser emitters and their receiving optics. Due to this arrangement we get a stable thermal behavior of the sensor. Furthermore this paper gives some detailed information about the accuracy, resolution and the measuring range of the sensor. One industrial application is listed at the end of this paper.
In the operation of an intelligent system, the role of multi-sensor integration and fusion can best be understood with reference to the type of information that the integrated multi-sensor can uniquely provide the system. The potential advantages gained through the synergistic use of this multi-sensor information can be decomposed into a combination of four fundamental aspects: the redundancy, complementarily, timeliness, and cost of the information. In this paper, the concept of fusion entropy is presented by generalizing the entropy theory, it is defined to be the posterior entropy of the fusion system. The validity of multi-sensor fusion is proved based on the transition of fusion entropy in information process; the result shows that the uncertainty in the output of a multi-sensor system is less than that in the output of a single sensor system. And then the rule to choose the multi-sensor is presented by the theorem.
The rapid development of information technology and e- commerce requires fast response form scheduling systems. Based on the Lagrangian relaxation approach for job shop scheduling, this paper present an integrated system that will generate schedules quickly. The Lagrangian relaxation approach is an iterative optimization process, where dynamic programming is solved in each iteration. Since dynamic programming is computational expensive especially for large problems, this paper develops the simplified dynamic programming, which will cut the computation time of each iteration by one order. Furthermore, a digital circuit to be embedded in PC is designed to implement the iterative optimization algorithm, leading to another order of speed improvement. The resulting integrated scheduling system consists of the hardware for optimization and the related software. It is estimated that two orders of magnitude gain in speed can be obtained, which will make on-line scheduling for practical job shops possible.
Automation of semiconductor manufacturing is a very large segment of the automation industry. The automation ranges from machinery capable of handling a single semiconductor wafer to automated material handling system that transport large numbers of these wafers at one time.
In hot plate mills the slabs from incoming reheat furnace are reduced to the desired width and thickness, being rolled out with considerable accuracy. The process of changing the plate width is controlled by a pair of edge rolls, which is called edger. The objectives of this edging process are to meet tight width tolerances of plates and to reduce the yield loss caused by trimming when irregular width is formed at the plate edge. There are several factors that result in complexity and uncertainty in width control. These include inaccurate edger set-up model, degradation of various mill equipment, variation of operation conditions, environments and variation of the dimension of incoming cast slabs. In this paper, a genetic algorithm-based PID control is proposed to ensure the control of the desired width at the exit of the mill. The approach adopted here is essentially optimization of the PID controller gains in order to minimize the error between the desired and actual slab width. Since the design parameters associated with genetic algorithm affect convergence performance, the effects of these parameters are investigated in detail. In addition, the control performance is also evaluated for various process parameters such as initial width of the incoming slab and temperature of the slab. Based on the result obtained from a series of simulations, the proposed control method is found to yield satisfactory performance for various process conditions.
In order to increase the tactile sensing range and allow larger AGV speeds that result in larger vehicle stopping distances, the recently reported fiber-optic 'curvature gauges' sensitized to their geometric curvature are arranged in loops around the AGV. When the AGV is driven into other objects, these loops deform, resulting in the change of their curvature - which is registered. While many different types of bumpers and whiskers have been sued in the past for a similar purpose, the key difference here is that no intermediate mechanical elements are employed to either transfer the impact loads onto the sensitive element or provide compliance to it. Optical fibers themselves provide both functions simultaneously. As a result, tactility is achieved within a comparatively large range extending over 10 cm. Throughout this range, virtually no reaction forces are generated with the impacting body. The range mentioned is on top of the one provided by the more traditional elastic bumper the optical fibers are mounted on.
Mechatronic systems incorporate multiple actuators and sensor which must be properly coordinated to achieve the desired system functionality. Many mechatronic systems are designed as one-of-a-kind custom projects without consideration for facilitating future system or alterations and extensions to the current syste. Thus, subsequent changes to the system are slow, different, and costly. It has become apparent that manufacturing processes, and thus the mechatronics which embody them, need to be agile in order to more quickly and easily respond to changing customer demands or market pressures. To achieve agility, both the hardware and software of the system need to be designed such that the creation of new system and the alteration and extension of current system is fast and easy. This paper describes the design of a Universal Mechatronics Coordinator (UMC) which facilitates agile setup and changeover of coordination software for mechatronic systems. The UMC is capable of sequencing continuous and discrete actions that are programmed as stimulus-response pairs, as state machines, or a combination of the two. It facilitates the modular, reusable programing of continuous actions such as servo control algorithms, data collection code, and safety checking routines; and discrete actions such as reporting achieved states, and turning on/off binary devices. The UMC has been applied to the control of a z- theta assembly robot for the Minifactory project and is applicable to a spectrum of widely differing mechatronic systems.
Agile assembly production means increased flexibility and intelligence needs for assembly equipment. One key area in this context is handling of parts as part of an automatic assembly process. In many case it is reasonable to use a freely programmable servo gripper. Normally these servo grippers are based on electrical actuators unlike on-off grippers, which are mostly pneumatic. This paper discusses result of a research project where a compact and intelligent servo pneumatic griper was developed. The main idea of the discussed research has been to design a gripper which could be used and integrate din any assembly robot and robot controller. The result is an independent system, needing only standard power supply, pressurized air and a standard bus giving good agility in automatic assembly.
In precision robotic assembly a small misalignment between parts to be assembled woudl always occur at the interface between mating parts due to positioning inaccuracy of robot, assembly fixtures and manufacturing tolerance of parts. This misalignment, however small can produce large contact forces, resulting in damage to parts or robots and thus lead to failure in assembly. Therefore the misalignment has to be detected and compensated accurately during mating period. For this purpose visual sensing technique has been widely used since it can detect rather large misalignment and also parts shape distance. In case of adopting camera, this technique usually obtain local information due to the limited range of its field of view. Furthermore, it can not avoid self-occlusion generated by the invisible region occluded by objects to be viewed. This problem has been a major hindrance to the success of assembly action when assembly is execute by a vision-based technique. In this paper, two novel visual sensing methodologies are developed to avoid such criticisms. Both system consists of four components: an inside mirror and outside mirror, a pair of plane mirrors and a camera with a collecting lens. The difference between the two is that the system A adopts conic mirror configuration, while the system B employs pyramidal one. Due to this configuration difference, the system A is shown to be capable of detecting two pi omni-directional image, while in addition to this functionality the system B can detect 3D measurement of objects with only one image capture. The measurement principles are described in detail and compared with each other. The image acquiring process is shown to easily detect the in-situ status of assembly action, while the recognition method is found to be effective to identify instantaneous misalignment between the peg and hole. The results obtained from a series of experiments show that the proposed visual sensing methods are an effective means of detecting misalignment between mating parts even in the presence of self-occlusion. The implication is that they will dramatically increase the rate of success when actually utilized in assembly process.
The subpixel imaging system with line-array CCD sensors and with area-array CCD sensors are introduced in the past paper. The system is consisted of a high-resolution lens, a beam splitter and two line-array CCD sensors or four area- array CCD sensor with subpixel displacements in the focal planes. In order to get a high spatial resolution in the pushbroom direction for pushbroom imaging system, the sample spacing between line images is decreased. Processing the original images got through the subpixel imagin system specially, a new image with higher spatial resolution could be constructed. The imaging system will be suitable for space application because the configuration is stable and rugged. The key techniques involved in the subpixel imagin system are the following: (1) the precision measuring technique of the CCD sensors' location and (2) the technique of the new image constructing.
The machining centers which implement manufacturing operation concentration in the highest degree can be used for complete machining of cylindrical type components, while these machines ensure the protectional procedures with stationary cutting tools typical of lathes and the protectional procedures with rotating cutting tools peculiar to drilling and milling machines. The GTIPROG-EC system, which was developed by us and can be run on IBM PC-s, is useful for operation planning of machining and making programs for manufacturing on turning centers. Our paper deals with the new results of development and the accuring problems. We especially examined the simulational possibilities of the GTIPROG/EC system.