Automated Assembly Systems Research Articles

Method for Energy-efficient Assembly System Design within Physics-based Virtual Engineering in the Automotive Industry

Automated assembly systems in the automotive industry require thorough virtual validation procedures complementary to early design stages and prior to commissioning and ramp-up. This contribution introduces a conceptual method to assure an energy-efficient assembly system design within the virtual validation procedure Virtual Engineering as pre-process to Virtual Commissioning. As initial step of the method, relevant system planning data (sequence diagram, BOM, etc.) is analyzed in order to identify energy consumption units (ECUs) and their activities in the manufacturing process. Subsequently, physics-based simulation capabilities based on game engine technology are used to model individual ECUs (electric motors, pneumatic drives, robots, etc.) of the production system and the entire manufacturing process in a virtual 3D-CAE simulation environment. The simulation delivers energy signatures of both the entire production system on an aggregated level as well as on an individual ECU-level. Based on this data, energy efficiency improvement measures are implemented and validated in the virtual model of the assembly system. This entails an energy-efficient production system design while maintaining predefined production system settings like cycle-time and output. The conceptual method is exemplified by a use case of an automated assembly system from the automotive industry presenting preliminary results.

Mechanical Design and Kinematic Simulation of Automated Assembly System for Relay

By means of Solid Works, three-dimensional model of automated assembly system was established, and kinematic simulation based on Solid Works Motion of assembly process for relay was performed. The simulation results proved the feasibility of mechanical design. Eventually, the productivity was estimated based on simulation analysis. The mechanical design provided a solution with high reference value to practical design of automated assembly system for relay.

Using Machine Vision for Flexible Automatic Assembly System

Flexible automatic assembly systems become the useful automation system for high mixed production lines of manufacturing processes. This research was aimed to design the primary prototype of the flexible automatic pick and place assembly system. We integrated the machine vision system with the robotic system to conduct a pick and place process. The product models consisted of a main part and an assembly part. The main parts were transferred to the mechanical system through a conveyor belt. When the main parts were held at the specific location, the images of the main parts were captured. Using the image processing of LabVIEW NI vision software and NI vision builder and image calibration method, we could obtain the shape, and orientation of assemble space in the main part which were used to control selective compliance articulated robot arm (SCARA). The SCARA was used to pick the assembly parts from the storage station and place them into the assembly spaces on the main parts. As the results of the prototyping, we evaluated the coordinate conversion factors from the image calibration and used them to control the movement of the SCARA. We finally obtained the reliable flexible automatic assembly system that could detect and identify the shape, and orientation of the assembly space correctly. The SCARA could also pick the correct assembly parts and place them into the assembly space perfectly.

Simulation of the behavior of pneumatic drives for virtual commissioning of automated assembly systems

Nowadays the development of complex automated assembly systems is almost impossible without the support of computer aided simulation methods. In order to increase the reliability of such simulations, the simulation models must depict the realistic, physically correct behavior of the assembly system. Thus, including the physical properties of the elements in the models allows for an increase in realism of the simulation. One of the challenging aspects in this field is the physical behavior of pneumatic drives. For simulating the correct pneumatic behavior in the validation procedure virtual commissioning, the simulation model must further meet real-time requirements. In this contribution a simulation model for the pneumatic behavior that can be used in virtual commissioning is presented. Physics based simulation capabilities based on game engine technology are applied, complemented by physics based modeling using thermodynamic laws. Additionally, the simulation model is quantitatively validated in terms of accuracy with respect to kinematics, dynamics, and compressed air consumption.

Experimental Validation of a Physics-based Simulation Approach for Pneumatic Components for Production Systems in the Automotive Industry

Automated assembly systems in automotive industry require thorough digital validation procedures prior to commissioning and ramp-up processes. One essential validation procedure is Virtual Commissioning, a method to test and validate real PLC-programs based on a virtual 3D-model of the production system using a HiL-approach. In order to increase the level of maturity of Virtual Commissioning and enrich the quality of the virtual 3D-model of the production system an innovative simulation approach using physics-based simulation capabilities based on game engine technology has been adopted. In particular, a physics-based model of pneumatic components (cylinders, clampers, etc.) typically found in automated assembly systems has been developed. The physics-based pneumatic model (PPM) enables more realistic simulations in real-time and is expected to be used within the next generation of Virtual Commissioning. However, before being utilized in industrial application PPM has to be validated. Kinematic and dynamic accuracy as well as compressed air consumption - a key performance indicator for energy consumption of the entire production system - of the PPM model are analytically and experimentally validated. In detail, validation was carried out considering different internal and external model parameters, such as pressure level, throttle valve settings, etc. and analyzing their impact on the PPM's informative value. Overall, PPM's validation shows promising results throughout all three different aspects (kinematics, dynamics, and compressed air consumption) and has thus a high potential for application in Virtual Commissioning.

Modeling and Verification of Reconfigurable and Energy-Efficient Manufacturing Systems

This paper deals with the formal modeling and verification of reconfigurable and energy-efficient manufacturing systems (REMSs) that are considered as reconfigurable discrete event control systems. A REMS not only allows global reconfigurations for switching the system from one configuration to another, but also allows local reconfigurations on components for saving energy when the system is in a particular configuration. In addition, the unreconfigured components of such a system should continue running during any reconfiguration. As a result, during a system reconfiguration, the system may have several possible paths and may fail to meet control requirements if concurrent reconfiguration events and normal events are not controlled. To guarantee the safety and correctness of such complex systems, formal verification is of great importance during a system design stage. This paper extends the formalism reconfigurable timed net condition/event systems (R-TNCESs) in order to model all possible dynamic behavior in such systems. After that, the designed system based on extended R-TNCESs is verified with the help of a software tool SESA for functional, temporal, and energy-efficient properties. This paper is illustrated by an automatic assembly system.

Human-robot Cooperation in Future Production Systems: Analysis of Requirements for Designing an Ergonomic Work System

Both humans and robots have crucial advantages regarding industrial assembly processes. While robots ace at repetitive and monotonous assembly steps, humans are able to adapt flexibly to new situations and upcoming problems. Combining these advantages by means of direct human-robot cooperation seems to be interesting for producing companies but has not been realized yet. While the corresponding technologies are already available, appropriate safety standards to ensure occupational safety are missing and represent one of the main barriers for introducing direct human-robot cooperation. This paper describes the requirements for a workplace, where humans and robots jointly perform an assembly process without separation between their workspaces. The requirements are identified in line with an ergonomic workplace for different aged working persons, whereas the robot assists the human with the assembly process. The analysis considers technical, human-related, and normative requirements. Afterwards, an early implementation of the concept is presented based on a cognitively automated assembly system using a lightweight robot.

Automated Experience-Based Learning for Plug and Produce Assembly Systems

This paper presents a self-learning technique for modular automated assembly systems. The technique consists of automatically acquiring experience on the changes made on an assembly system to cope with new production requirements or to recover from disruptions. Experience is generalised into operational knowledge that is used to aid operators in future adaptation processes. The experience model and the self-learning technique reflect the modular structure of the assembly machine and are particularly suitable for plug and produce systems, which are designed to offer high levels of self-organisation.

An Interdisciplinary and Hands-on Learning Approach for Industrial Assembly Systems

Planning and realisation of industrial assembly systems is an interdisciplinary task that requires theoretical and experience-based knowledge in diverse fields (e.g. product design, industrial engineering, automation and robotics). In order to develop students’ competences, the Institute of Production Systems introduced the two-step course series “Industrial Assembly”. It combines transfer of interdisciplinary theoretical knowledge lectured by different professorships and hands-on tasks in manual and automated assembly systems training environments with a realistic industrial assembly setting. The paper describes the learning objective and procedure of the course series “Industrial Assembly” and underlines the relevance of this interdisciplinary and hands-on learning approach.

Retraction Note: Applying TRIZ and AHP to develop innovative design for automated assembly systems

Innovative design in the development of new product and process has become the core value in most business establishments. These innovative designs are often associated with the long-established trade-off compromises or conflicting performance parameters where speed and reliability or quality and cost are readily acknowledged. The rate of change in technology and the commercial environment suggests that the opportunity for innovative design is accelerating and systematic support for innovation process is needed. This study combines the Russian theory of inventive problem solving (TRIZ) and the analytical hierarchy process (AHP) for designing the automated manufacturing systems. This study applied the contradiction matrix table, 40 innovative principles, and 39 engineering parameters to compromise the trade-off between design contradictions and engineering parameters. The design engineers can acquire more feasible solutions and inspiration through the proposed approach. However, due to vagueness and uncertainty in the decision maker’s judgment, an AHP is employed as a decision support tool that can adequately represent qualitative and subjective assessments under the multiple criteria decision making environment. Moreover, the proposed approach can help decision makers facilitate the selection and evaluation of innovative designs in the presence of intangible attributes and uncertainty. In short, the objectives of this research are to use TRIZ to propose the automated design alternatives under the innovative design consideration and to use an AHP to evaluate and select the best feasible alternative under multiple criteria. A case study of designing automated connector assembly line has been used to demonstrate the applicability of the proposed approach.

Calibration of robotic drilling systems with a moving rail

Industrial robots are widely used in aircraft assembly systems such as robotic drilling systems. It is necessary to expand a robot’s working range with a moving rail. A method for improving the position accuracy of an automated assembly system with an industrial robot mounted on a moving rail is proposed. A multi-station method is used to control the robot in this study. The robot only works at stations which are certain positions defined on the moving rail. The calibration of the robot system is composed by the calibration of the robot and the calibration of the stations. The calibration of the robot is based on error similarity and inverse distance weighted interpolation. The calibration of the stations is based on a magnetic strip and a magnetic sensor. Validation tests were performed in this study, which showed that the accuracy of the robot system gained significant improvement using the proposed method. The absolute position errors were reduced by about 85% to less than 0.3mm compared with the maximum nearly 2mm before calibration.

The Control System of Virtual Simulation and Speed Optimization on Assembly Manipulator

Considering the characteristics and control requirements of assembly line, we develop a virtual simulation system which combines virtual reality and electrical control technology. The system can be used in system monitoring, debugging and staff training. The electrical control program is written by software of Rockwell based on virtual PLC, which realizes the application of velocity curve in linear type and Cosine-linear type on the object of virtual simulation through the RSTestStand software to build 3D virtual simulation model of the automatic assembly system of manipulator. The motion visual effect and monitor curve on the object of virtual simulation can indicate that the control system works well. It can also reduce mechanical arm joint motion and force effectively, through the start and stop, acceleration and deceleration of the manipulator movement and optimization of the speed using cosine timing scheme in uniform conversion.

Flexible Automated Assembly Systems for Large CFRP-structures

Abstract In this publication an approach for flexible automated assembly systems for large CFRP-structures will be presented. This approach divides the assembly system into two main components, the automated joining process and the flexible automated holding fixture. Special attention will be given to the holding fixture, its components and automatic processes to achieve an optimal 6D-position and shape of the CFRP-structure to be assembled. First, a short overview about the state-of-the-art assembly systems will be given, followed by a description of the approach and the developed generic prototype for flexible automated holding fixtures. The prototype will be presented as a future solution that opens new possibilities of adaptive assembly optimization in comparison to conventional part specific systems. Furthermore, the main automatic processes applied to the generic prototype will be presented as independent technologies working together as an intelligent system. The automatic processes to be described are machine measurement, contact-points adjustment, 6D-position adjustment and shape adjustment.

Establishing Energy Efficiency as Criterion for Virtual Commissioning of Automated Assembly Systems

Physics engines, originating from gaming industry, are lately employed to perform realistic virtual simulations in early phases of assembly systems development processes. In particular, physics engine-based Virtual Commissioning boosts level of maturity of assembly systems due to advanced real-time collision detection and precise cycle time determination. This paper describes the improvement of DAIMLER's Virtual Commissioning process by virtually predicting and visualizing mechanic energy consumption of automated assembly system components using a physics engine. Based on simulation results, established approaches for reducing energy consumption of automated assembly system can be implemented in the virtual model.

A Decade of High Accuracy Die Attach Equipment and Process Developments (Addressing Photonics Device Packaging Challenges)

Fueled by the Internet and nowadays unlimited connectivity expectations, the assembly of optoelectronic packages became a key element to enable the explosive growth in the communication field around the entire globe. The primary challenge in the field of advanced optoelectronics and photonic device packaging (e.g. laser diodes, VCSEL's, optical benches, lenses etc.) is to accurately align the different optical components in reference to each other for optimal optical device performance. This growing need for high precision die attach (<= 0.5um @ 3 sigma) systems and solutions at the shortest possible cycle times has been studied and implemented by AMICRA Microtechnologies. AMICRA's state of the art high accuracy automated assembly system solutions have been successfully used for over a decade in both a laboratory setup and a high volume manufacturing environment. From handling a large variety of substrate materials, thin and fragile chips with odd aspect ratios, lenses and other components, the flexible and dynamic vision alignment concept and the bonding process controls required to achieve high overall component placement accuracies has been AMCIRA's industry focus since the company's inception. While significant progress has been made to provide solutions for all communications and photonics applications there are currently still some challenges out there to be overcome, challenges that can also change on an application by application basis. Besides the technical challenges the cost effectiveness or cost per bond for those applications is a very critical overall success factor as well. This paper will elaborate on manufacturability concerns and equipment automation challenges associated with the key parameters of a Photonics applications high accuracy die attach process which, amongst others, not only require highly sophisticated vision alignment algorithms but also thermal transfer processes either using an eutectic process or a laser soldering technique. Given the ever shrinking packaging form factors, all of AMICRA's research and developments in the Photonics field have also been successfully introduced and applied in more traditional semiconductor applications which have an increasing need for high accuracy die attach.

A Simulation Study on the Layout Design of Micro Assembly Line for Lens Module

Phone-camera lens module is composed of several components which are assembled together with a given sequence. Assembly processes are conducted in an assembly line which could be a manual type or automatic type. There have been many types of automated assembly system for lens module assembly to enhance the productivity and save the labor cost. Micro assembly system introduced in this paper is another automated system having the merits of space saving and flexibility. The micro assembly line is constructed with several micro assembly machines, numbers of conveyors and a mini-crane for material handling. To compare the productivity of the micro assembly line, three layout types of rotary table with different assembly process were designed, and they are evaluated using simulation.

Development of a Self-Learning, Automatic Parameterisation of an Aerodynamic Part Feeding System

The individualisation of customer requirements and the increasing pressure to reduce manufacturing costs due to the internationalisation of markets requires undertakings to react flexibly and to ensure long-term competitiveness through innovations in production processes. As far as lowering manufacturing costs is concerned, there is considerable potential for rationalisation in assembly work. At the same time, it is expected that the provision and supply of parts in automated assembly systems will become a bottleneck in future with regard to quality, time and costs. The reason for this is that the part feeding systems traditionally used are stretched to their limits in terms of supply performance, flexibility and process reliability. Orienting parts in feeding systems is often the most technically demanding process. Active, aerodynamic orientation systems for feeding parts have been developed at the Institute of Production Systems and Logistics. The system’s parameters have had to be configured manually by experienced technicians to date. This work takes up a great deal of time. In order to minimise this time spent by users, a genetic algorithm (GA) is developed in this paper, which enables the optimum parameter values for unknown parts to be identified automatically. To this end, the optimisation problem to be solved, namely to identify the parameter values for aerodynamic orientation, is first described mathematically. The structure of the GA and its method of functioning are then explained. A methodology to accelerate the convergence speed of the GA is presented in this context, in that the quantity of individuals in each generation and the number of test parts observed is adapted to the quality of the solution in order to shorten the time needed to find the solution.

Modelling and optimization of fully flexible assembly systems (F‐FAS)

PurposeThe paper aims to address the modelling and optimization of fully flexible assembly systems (F‐FAS), a new concept in flexible automation recently introduced by the authors.Design/methodology/approachThe paper presents a mathematical model of the F‐FAS, which makes it possible to predict its efficiency, throughput and unit direct production costs, correlating such values with system and production variables. The mathematical model proposed in the paper was derived from experimental and simulation data, which were analysed for a wide range of different productions and system settings.FindingsCorrelation analysis revealed that there are three main determinants of the efficiency of the F‐FAS: the number of components (types of parts) used to assemble the models (production variable); the average complexity of the models to be assembled (production variable); the ratio of the average perimeter of components (production variable) over a significant dimension of the working plane (system variable). Such parameters makes it possible to estimate the maximum attainable efficiency of the F‐FAS, and to calculate the optimal setting of the feeder which makes it possible to obtain such efficiency during the execution of the whole production order.Originality/valueThe model presented in the paper makes it possible to quantify in advance the real potential of the F‐FAS, according to the characteristics of the production mix and type of components to be assembled. By using the methodologies presented in the paper, one can first evaluate the convenience of the F‐FAS approach with respect to traditional FAS technology and manual assembly, then identify the optimal design and settings of the F‐FAS, according to the needs of a specific application. As a result, not only can the investment on the automated assembly system be accurately evaluated in advance, but also the return on investment can be maximized.

Life cycle oriented evaluation of flexibility in investment decisions for automated assembly systems

Due to fast changing market requirements and short product life cycles, flexibility is one of the crucial characteristics of automated and partly automated assembly systems besides purchasing and operation costs. Since the life cycle of an assembly system is longer than the one of the assembled products, flexibility enables an assembly system to adapt to future product requirements as well as production scenarios. The approach proposed in this paper strives for a systematic and economic measurement of flexibility in investment decisions. It offers methods and key-figures supporting the investment decisions for automated assembly systems. The right levels of flexibility and automation of an assembly system are evaluated by using a set of potential future scenarios of the system's life cycle. Based on two new key-figures called Return on Automation and Return on Flexibility, the approach allows comparing different configurations of an assembly system and therefore supports well-informed investment decisions.

The Application of Machine Vision in Automatic Assembly of Locks

In the automatic assembly of locks system the pins’ selection depends on depth of key’s groove. Although the kinds of groove’s depth are fixed, the arrangements are random and they can’t be unpredictable. The difference in depth of key’s groove is very small, so it can’t be judged by eyes accurately. To solve the problem that the pins assembly is tried frequently, the depth of keys’ groove can be measured accurately by the machine vision. So the problem of the serious influence production efficiency is solved successfully. This kind lock is widely used and machine’s cost is very low by allocation. The experiments show that this method fully met the locks automatic assembly system requirements from the assembly precision, real time performance and robustness and other aspects, solving the problems encountered in the lock assembly.