Analysis of Automatic Teaching Position Error to Optimize OLP (Off Line Programming) for Grinding/Lapping Robot System Using Laser Tracker

A robotic simulation and off-line programming package has been developed for use on Silicon Graphics workstations that has the capability of using several types commercially available virtual reality (VR) hardware devices. The software includes a library of 4, 5, and 6 degree-of-freedom (DOF) industrial robots with closed form inverse kinematics and translators that convert graphical simulation commands into the device control language that can be transferred to the robot control hardware. Forward kinematics, inverse kinematics, and joint space path planning methods used in the software development are discussed. The performance of three types of commercially available 6-DOF input devices are compared for use in interactive off-line programming. Stereo vision and external 6-DOF positioning devices were added to enhance programming efficiency and offer more realistic access to the virtual workcell environment.

The use of industrial robots for welding automation is a major and expanding applications area. In a welding task, the robot should smoothly trace along the weldseam with appropriate tool poses. For welding a complex 3-D curve, a large number of points should be taught to make the weld path smooth. This is a very tedious job and is not an easy way to leach the robot. In this paper, the requirements of a CAD system to be used as a robotic off-line arc-welding programming system are discussed. An off-line programming system for such application was developed. The workpieces and the weldseam were represented by analytical geometries. The positions and orientations of the weldgun along the trajectory were analysed by the task requirement of the welding procedure and solved by differential geometry. Calibration process was discussed to ensure programs were properly executed. This system is especially useful for off-line programming for the welding of complex 3-D curves.

Processing configuration off-line optimization for functionally redundant robotic drilling tasks

In order to realize automatic flexible drilling with high efficiency and good quality, a drilling system was established, which integrates the technology of laser measurement, off-line programming, computer control and robotics. In this system, the key coordinate frames are established by the laser tracker, the drilling programs are generated by the off-line programming and simulation system, the communication between the automatic drilling control system and the robot control system is based on the socket technique. By running drilling program, the moving platform, robot and the end effector can work automatically and harmoniously. In addition, the deviation compensation methods of hole position and its normal vector are proposed. The experimental results show that the efficiency of drilling can achieve 6 holes per minute, the position accuracy can be effectively controlled within 0.3mm, and the normal accuracy is better than 0.5°.

In this paper, a collision contact modeling method for virtual reality environments is presented. Models in virtual environments are typically represented using triangle meshes. Most traditional collision contact simulations require the surface information of rigid bodies. This makes traditional collision contact simulations inapplicable for most virtual environments. This paper presents methods to model the behavior of colliding objects in virtual environments using triangle mesh representations of the objects. RAPID™ is used to obtain the approximate collision contact information between individual triangle meshes. Impulse calculations are combined with the collision detection to simulate post-collision behavior of objects. A three-point method is introduced to calculate the final resting place of objects or calculate unstable equilibrium and further dynamics of objects. These methods have been integrated with the Virtual Assembly Design Environment (VADE) to enhance VADE’s existing dynamics simulation capabilities. A series of test cases are presented and analyzed to validate these new methods.

We present faceton, a geometric modeling primitive designed for building architectural models, using a six degrees of freedom (DoF) input device in a virtual environment (VE). A faceton is given as an oriented point floating in the air and defines a plane of infinite extent passing through the point. The polygonal mesh model is constructed by taking the intersection of the planes associated with the facetons. With the simple drag-and-drop and group interaction of faceton, users can easily create 3D architecture models in the VE. The faceton primitive and its interaction reduce the overhead associated with standard polygonal mesh modeling in VE, where users have to manually specify vertexes and edges which could be far away. The faceton representation is inspired by the research on boundary representations (B-rep) and constructive solid geometry (CSG), but it is driven by a novel adaptive bounding algorithm and is specifically designed for the 3D modeling activities in an immersive virtual environment.

The article discusses possible forms of educational STEM projects in the field of electronics and device control using Arduino controllers. As you know, the implementation of such STEM projects can be carried out not only using various electronic constructors, but also using virtual modeling environments. The knowledge obtained during modeling in virtual environments makes it possible to increase the efficiency of face-to-face practical training with a real constructor, and to improve the quality of students’ knowledge. The use of virtual modeling environments in combination with the use of real constructors provides links between distance and full-time learning. A real constructors can be used simultaneously by both the teacher and the student, jointly practicing the features of solving practical problems. The article provides examples of using a virtual environment for preliminary prototyping of circuits available in the documentation for electronic constructors, to familiarize students with the basics of designing and assembling electronic circuits using the surface mounting method and on a breadboard, as well as programming controllers on the Arduino platform that control electronic devices. This approach allows students to accelerate the assimilation of various interdisciplinary knowledge in the field of natural sciences using STEM design.

The engineering process of creating cell control systems is described, and a Cell Control Engineering (CCE) concept is defined. The purpose is to assist people, representing different disciplines in the organisation, to implement cell controllers by addressing the complexity of having many systems in physically and logically different and changing manufacturing environments. The defined CCE concept combines state-of-the-art of commercially available enabling technologies for automation system software development, generic cell control models and guidelines for the complete engineering process. It facilitates the understanding of the task and structure of cell controllers and uses this knowledge directly in the implementation of the system. By applying generic models CCE facilitates reuse of software components and maintenance of applications. In many enterprises, software makes up an increasing part of any production installation and in addition the software element is often very critical as it is the integrating, controlling and co-ordinating system component. As such, a CCE concept providing high quality and high functionality as well as flexibility is an important aspect of a company's automation strategy. The concept has been validated and verified at ODENSE STEEL SHIPYARD Ltd. in several robotic arc welding systems in the production using an application enabler, UNIX, X, SQL and (wireless) Ethernet. Integration with off-line programming, production planning, monitoring and maintenance has been achieved resulting in increased utilisation of the capability and capacity of the robot systems.

INTRODUCTION: Augmented Reality (AR) offers the benefit of improved hand-eye coordination by accurately superimposing 3D stereoscopic displays for surgical instruments onto anatomic landmarks. METHODS: 120 pedicle screws were implanted using an AR system (OnPoint AR, OnPoint Surgical, Bedford, MA) (thoracic 50, lumbosacral 70; pre-op CT 40, O-arm 80). Heary grading was applied by an independent radiologist assessing the degree of pedicle breaches. 3D measurements of positional error (PE) and angular error (AE) were performed by comparing post-operative CT scans of implanted screws with planned trajectories. Statistical analyses compared PE and AE for OnPoint AR with the available values for other systems using an unequal variance t-test method. RESULTS: 113 screws placed demonstrated Heary grade 1 accuracy. 6 screws had a larger diameter than the pedicle and were planned with in-out-in technique with Heary grade 2 accuracy. One screw demonstrated a lateral breach (grade 2) caused by a loose connection to the screwdriver. PE and AE (mean ± 1SD) for OnPoint AR were the following: for intra-operative spin 1.1mm±0.5mm and 1.3°±0.5°; for pre-operative CT 1.9mm±1.2mm and 2.2°±1.3°. Percent increment in PE and AE for Medtronic Stealth Station, Brainlab navigation, Stryker nav3i, Medtronic Mazor X robot, Globus Excelsius robot, Augmedics Xvision, and Novarad VisAR compared to OnPoint AR ranged between 40–80%, with differences being highly significant for all comparisons. CONCLUSIONS: PE and AE for placing pedicle screws are statistically significantly smaller for the novel AR system compared to existing navigation, robotic, and AR systems. A positional error of 1.1mm and angular error of 1.3° makes this technology particularly suited for small pedicles, challenging anatomy, and MIS techniques.

Intramural productive practical training base play a very important role for training quality of engineering practical ability of higher vocational institute students. Hardware condition confines serious impact on practical effect of the practice teaching of mould professional in engineering vocational. In order to solve the prominent contradictions, we build productive mould training base cooperation with enterprises-the complete practice teaching mold manufacturing process is introduced to the practical teaching with mold manufacturing equipment and sites provided by school; guidance teachers, engineers and technicians guide students with co-training by division of responsibilities. As students to participate in the full mold manufacturing process in real situations, the training model trained professional core competence and innovative ability, greatly mobilized the enthusiasm of the students and received a good training effect.

The Wide Field Phasing Testbed for the Giant Magellan Telescope1 is comprised of six pairs of off-axis parabolas, an Offner relay and several additional fold mirrors. To align this optical system we used a Leica laser tracker and a 4D interferometer. The laser tracker was used to accurately position each fold mirror on the optical bench by measuring the position of a spherically mounted retroreflector with the laser tracker, first directly and then in reflection off the mirror to be aligned. The mirror was adjusted until the reflected image was in the correct location. Key to this operation was custom software that read in the Zemax prescription file specifying the location of each optic; interfaced with the laser tracker to measure the location of fiducial SMRs on the optical bench; performed transformations between coordinate systems attached to the laser tracker, the optical bench, the Zemax model, and the individual optics; and finally displayed the real-time position errors in a large font so that the optic could be easily adjusted to the correct location. The OAPs were also positioned using the laser tracker in conjunction with the interferometer. An SMR was placed at the desired focal position of the OAP using the laser tracker. This same SMR served as the return sphere for the interferometer which was used to adjust out tilt and astigmatism errors. With this system we were able to align the full optical system efficiently and in a deterministic way.

Path deviations caused by geometrical errors in machining equipment significantly affect the machining quality of optical components. To enhance the quality and efficiency of optical component processing, this paper presents a Chebyshev interpolated Levenberg-Marquardt algorithm (CILM) aimed at compensating for path deviations in a robotic smoothing system utilized for optical component processing. First, the positioning accuracy of the robotic smoothing system is measured using a laser tracker. Subsequently, an objective function is constructed based on robot kinematics and error models to optimize the geometric errors in the system. Then, the proposed method is adopted to identify the geometric parameters of the robotic smoothing system to compensate for the smoothing path deviations. The compensation results confirm the effectiveness of the proposed method in enhancing the absolute positioning accuracy of the robotic smoothing system. Additionally, experimental verification is conducted to validate the effectiveness of the proposed method in improving the surface quality of optical components through smoothing path compensation. The results of the three experiments indicate that the proposed CILM achieves optical components with peak-to-valley values 15.70%, 28.7%, and 4.01% lower than those obtained before compensation, along with root mean square of 33.67%, 21.57%, and 10.23% lower than before compensation values, respectively. Moreover, the power spectral density curves of CILM exhibit smoother characteristics in comparison to the curves before compensation.

This paper presents an interactive computational system for developing architectural compositions within a 3D real-time virtual environment. The features of implemented system within the interface of Activeworlds platform includes (a) providing a set of 3D building objects that are made available within the virtual environment and can be utilized by the user to construct architectural compositions; (b) allowing users to modify both geometrical and non-geometrical properties of these objects; and (c) maintaining interrelationships between these objects using constrain-based rules automated by the developed system in real-time. The developed IAMVE (Interactive Architectural Modeling in Virtual Environments) system provides more flexibility to architectural designers and develops an edge to multi-user real time 3D virtual environments to be better utilized in the context of architectural design

This paper discusses the proposed model of the collaborative virtual learning system for the introductory computer programming course which uses one of the collaborative learning techniques known as the “Think-Pair-Share”. The main objective of this study is to design a model for an online learning system that facilitates the collaborative learning activities in a virtual environment such as online communications and pair or small group discussions. In order to model the virtual learning environment, the RUP methodology has been used where it involves the data collection phase and the analysis and design phase. Fifty respondents have been randomly selected to participate in the data collection phase to investigate the students’ interest and learning styles as well as their learning preferences. The results have shown the needs for the development of online small group discussions that can be used as an alternative learning style for programming courses. The proposed design of the virtual learning system named as the Online Collaborative Learning System or OCLS is being depicted using the objectoriented models which are the use-case model and class diagram in order to show the concise processes of virtual “Think-Pair-Share” collaborative activities. The “Think-PairShare” collaborative learning technique that is being used in this model has been chosen because of its simplicity and relatively low-risk. This paper also presents the proposed model of the system’s architecture that will become the guidelines for the physical development of OCLS using the web-based applications.

Virtual environments are often used for training. In particular, virtual worlds can be used for situation-awareness. Such models allow users to gain an understanding of a real-world location or walk-through scenarios that may incorporate many participants and achieve training to develop skills and competencies. One of the main challenges for the developer is to create virtual models that are appropriately sized in comparison with the avatars. In-world measurements are different to those in the real-world. In-world models have exaggerated avatar heights and often use third-person viewing projections. This article describes our experience with developing a scale model. We have used Second Life to provide a case study for understanding virtual design issues and challenges of scale in development. We discuss these challenges and describe our experiences of developing real-world models in virtual environments.