Safety analysis of mechatronic product lines

Most methodologies for the design and analysis of mechatronic systems target a single product. From a business perspective, successful product development requires shortening development times, reducing engineering costs and offering a greater variety of product options for customers. In software engineering, the software product line (SPL) technology has been developed to meet these conflicting goals, and several major companies have reported success stories resulting from SPL adoption. In mechanical engineering, similar methodologies have been developed under the name of product platforms. Methodologies for analyzing product qualities such as safety or reliability have been introduced for both SPL and product platforms. The problem with these methodologies is that they consider either software or mechanical product design, so they do not guide developers to find the best balance between the controller and the equipment to be controlled. Several system properties of a mechatronic product line should be investigated with mechatronic analysis methodologies before the development process branches to software, electronic and mechanical design. In particular, safety is one system property that can only be analyzed by considering both the equipment and its controller, so mechatronic methodologies early in the design are advantageous for discovering safety-related design constraints before costly design commitments are made. This paper extends the Functional Failure Identification and Propagation (FFIP) framework to the safety analysis of a mechatronic product line with options in software signal connections and equipment. The result of applying FFIP is that unsafe combinations of options are removed from the product line.     

A design paradigm for mechatronic systems

Concepts of mechatronics are applicable in the design of complex and multi-domain dynamic systems. This paper presents an approach based on the mechatronic design quotient (MDQ) for systematic design of a mechatronic system. Traditional procedures of design are hierarchically separated into topological design and parametric design. Extending this concept, an MDQ may be “structured” into a multi-layered hierarchy. The approach and significance of the application of MDQ in mechatronic design are indicated using illustrative examples.     

System-Based and Concurrent Design of a Smart Mechatronic System Using the Concept of Mechatronic Design Quotient (MDQ)

A mechatronic system needs an integrated, concurrent, and system-based design approach due to the existence of interactions among its subsystems, and also the existence of interactions between the criteria involved in a realistic evaluation of a mechatronic product. This paper presents a systematic methodology for a detailed mechatronic design based on a mechatronic design quotient (MDQ). MDQ is a multicriteria index, reflecting a system-based evaluation of a mechatronic design, which is calculated using soft computing techniques, thereby accommodating interactions between criteria and human experience. A niching genetic algorithm is utilized to explore the huge search space raised due to concurrent and integrated design approach, with the aim to find the elite representatives of different possible configurations. To demonstrate the method, it is applied to an industrial fish cutting machine called the Iron Butcher-an electromechanical system that falls into the class of mixed or multidomain systems.     

Interface model enabling decomposition method for architecture definition of mechatronic systems

Solving a complex problem often requires a way to break it down into smaller, interconnected and manageable sub-problems, and then to join them together. The concept of breaking down a problem into smaller pieces is generally referred to as decomposition. The design of mechatronic systems is an example of such complex problems, as it is based on the integration of several disciplines, such as mechanical, electrical and software engineering. Decomposition is thus a common technique to help designers to obtain solutions for the design of mechatronic systems during the systems engineering process. However, an effective decomposition method which can fully solve the design problems of mechatronic systems has not yet been proposed in systems engineering.The goal of the paper is to formalise this decomposition method based on an interface model. This method is applicable to the architecture definition in the context of the design of mechatronic systems during their conceptual design phase. The proposed decomposition method provides designers with high-level guidance to help them to achieve the appropriate hierarchies and granularities for the architecture of mechatronic systems. The proposed decomposition method is applied and demonstrated using the systems engineering practices of a 3D measurement system.     

Design of Mechatronic Systems With Configuration-Dependent Dynamics: Simulation and Optimization

This paper considers the simulation and optimization of mechatronic systems with configuration-dependent dynamics. A modeling methodology, able to capture the varying dynamics and the embedded control system actions, using affine reduced models and cosimulation, is proposed. In this way, mechatronic systems with configuration-dependent dynamics can be evaluated during the design phase. This methodology is applied to a pick-and-place assembly robot and an experimental validation is carried out. The mechatronic design approach, which takes into consideration structural and control parameters, is considered. Using time-domain metrics, two control strategies are derived: a linear time-invariant proportional--integral--derivative (PID) controller and a linear parameter-varying PID controller. Finally, design tradeoffs are evaluated in a truly mechatronic approach.      

Synthesis of modular mechatronic products: a testabilityperspective

Producing modular products that combine modules with the consideration of product performance, e.g., testability of electronic systems, is frequently stated as a design goal. However, most of mechatronic frameworks (models) discussed in the literature do not consider testability of electronic subsystems of mechatronic products. This paper assumes that the product modules have been established, and aims at the development of modular mechatronic products with the consideration of testability of electronic subsystems as a performance criterion. The generation of modular products and module testability issues are discussed. Testability points, testability values, and access paths for a module/system are crucial to the generation of modular mechatronic products. A generalized label-correcting algorithm is developed to determine the points of focus, testability values, and access paths in modules     

Model-integrated mechatronics - toward a new paradigm in the development of manufacturing systems

The traditional approach for the development of manufacturing systems considers the constituent parts of the system, i.e., mechanical, electronic, and software, to be developed independently and then integrated to form the final system. This approach is being criticized as inappropriate for the complexity and the dynamics of today's systems. This paper proposes an architecture that promotes model integration not only for implementation space artifacts but also in artifacts of the early analysis and design phases of the development process. The proposed architecture, which promotes reuse and significantly decreases development and validation time, is at the heart of a new paradigm called model-integrated mechatronics (MIM). MIM applies domain-specific modeling languages for the concurrent engineering of mechanical, electronic and software components of mechatronic systems. It simplifies the integrated development process of manufacturing systems by using as basic construct the mechatronic component. The MIM paradigm was utilized to define "Archimedes," a system platform that supports the engineer through a methodology, a framework, and a set of tools to automate the development process of agile mechatronic manufacturing systems.     

Design for control-a concurrent engineering approach formechatronic systems design

The well-accepted basis for developing a mechatronic system is a synergetic concurrent design process that integrates different engineering disciplines. In this paper, a general model is derived to mathematically describe the concurrent design of a mechatronic system. Based on this model, a concurrent engineering approach, called design for control (DFC), is formally presented for mechatronic systems design. Compared to other mechatronic design methodologies, DFC emphasizes obtaining a simple dynamic model of the mechanical structure by a judicious structure design and a careful selection of mechanical parameters. Once the simple dynamic model is available, in spite of the complexity of the mechanical structure, the controller design can be facilitated and better control performance can be achieved. Four design scenarios in application of DFC are addressed. A case study is implemented to demonstrate the effectiveness of DFC through the design and control of a programmable four-bar linkage     

Optimal construction and control of flexible manipulators: a case study based on LQR output feedback

A mechatronic approach is studied here to design the mechanical system and controller concurrently for a robotic flexible manipulator. There is no coupling effects among these components which exit in traditional sequential design and this concurrent development leads to the global optimal performance. A linear quadratic regulator with output feedback is used to compare the results obtained from the traditional approach and this mechatronic approach. Using the mechatronic approach, optimal beam shapes as well as the associated optimal controllers for different feedback structures and for different objective functions can be achieved. Numerical results have indicated substantial improvements on performance.     

利用UG软件建立机械电子产品三维设计平台

对利用UG软件建立机械电子产品三维设计平台进行了探讨,提出了统一公共环境参数、定制模板、模式文件、建立标准件及公用件库、规范文件命名及目录体系等方面的解决方案。该方案已经成功应用于机械电子产品三维结构设计的工程应用中,明显提高了设计效率和质量。     

Nonlinear control of mechatronic systems with permanent-magnet DC motors

The current trends in development and deployment of advanced electromechanical systems have facilitated the unified activities in the analysis and design of state-of-the-art motion devices, electric motors, power electronics, and digital controllers. This paper attacks the motion control problem (stabilization, tracking, and disturbance attenuation) for mechatronic systems which include permanent-magnet DC motors, power circuity, and motion controllers. By using an explicit representation of nonlinear dynamics of motors and switching converters, we approach and solve analysis and control problems to ensure a spectrum of performance objectives imposed on advanced mechatronic systems. The maximum allowable magnitude of the applied armature voltage is rated, the currents are limited, and there exist the lower and upper limits of the duty ratio of converters. To approach design tradeoffs and analyze performance (accuracy, settling time, overshoot, stability margins, and other quantities), the imposed constraints, model nonlinearities, and parameter variations are thoroughly studied in this paper. Our goal is to attain the specified characteristics and avoid deficiencies associated with linear formulation. To solve these problems, an innovative controller is synthesized to ensure performance improvements, robust tracking, and disturbance rejection. One cannot neglect constraints, and a bounded control law is designed to improve performance and guarantee robust stability. The offered approach uses a complete nonlinear mechatronic system dynamics with parameter variations, and this avenue allows one to avoid the conservative results associated with linear concept when mechatronic system dynamics is mapped by a linear constant-coefficient differential equation. To illustrate the reported framework and to validate the controller, analytical and experimental results are presented and discussed. In particular, comprehensive analysis and design with experimental verification are performed for an electric drive. A nonlinear bounded controller is designed, implemented, and experimentally tested.     

Integrated structure and control design for mechatronic systems with configuration-dependent dynamics

This paper considers the optimal design of mechatronic systems with configuration-dependent dynamics. An optimal mechatronic design requires that, among the structural and control parameters, an optimal choice has to be made with respect to design specifications in the different domains. Two main challenges are treated in this paper: the non-convex nature of the optimization problem and the difficulty in modeling serial machines with flexible components and their embedded controllers. The optimization problem is treated using the direct design strategy which considers simultaneously structural and control parameters as variables and adopts non-convex optimization algorithms. Linear time-invariant and gain-scheduling PID controllers are addressed. This methodology is exploited for the multi-objective optimization of a pick-and-place assembly robot with a gripper carried by a variable-length flexible beam. The resulting design tradeoffs between system accuracy and control efforts demonstrate the advantage of an integrated design approach for mechatronic systems with configuration-dependent dynamics.     

Telescopes as mechatronic systems

The system design of telescopes is usually dominated by the aspects of the optics and receiving instruments. The telescope structure, mechanism, and control are "only" aids to position these elements toward the celestial target, but their quality has a big impact on the final performance. This paper describes an integrated design approach to these "mechatronic" telescope subsystems.     

挠性印制板设计及其在系统设计中的应用

挠性印制板以其轻、薄和可弯曲等特点得到广泛的应用.与传统的刚性印制板相比,挠性印制板的设计有很多特殊的要求.以多种形式对挠性印制板的设计进行了说明.挠性印制板因其自身的特点,根据其外形及应用的环境,对其进行针对性设计,在系统设计中还能起到独到的作用,发挥出挠性印制板的独特的优势.     

液晶显示器模组黑态均匀性改善研究

随着显示行业发展,市场对液晶显示品质提出了更高的要求,特别是车载等领域,背光亮度几乎在10 000cd/m2以上,此时显示装置的细微缺陷可能被凸显进而影响画面显示品质。黑态均匀性是液晶显示模组显示画质的重要指标,为提升液晶显示模组黑态均匀性,改善显示画质,特对可能造成黑态漏光的相应结构及设计进行研究。从液晶面板受外力方向,针对机构干涉及柔性电路板(FPC)应力两方面的影响因素设计实验,确定出利于提升黑态均匀性的设计方法或管控标准。实验结果表明,通过对背光及铁框平整度的管控及缓冲胶带优化可减少机构干涉应力,通过对FPC结构及外形设计优化可减少FPC弯折应力,通过玻璃厚度减薄及增大下偏光片尺寸可提升液晶面板抗变形能力,从而将模组黑态均匀性提升到80%以上。     

Model-based system design of annealing simulators

We discuss several aspects of mechatronic product development processes, such as finding and evaluating design concepts and dependencies between design parameters. One of the key issues in the development of modern mechatronic systems is the benefit of consistent integration of mechanical, electrical, and electronic control and software aspects from the very beginning of the earliest design phases. Even for a single design problem defined by a given specification, different designers will probably respond with a variety of different design concepts, each of which may be acceptable in terms of meeting the specification. In the conceptual design phase, we propose that some aspects of design, such as hierarchy of parameters and modularity of the design, are analysed with conceptual models. The application presented in this paper shows the conceptual design of an experimental laboratory annealing simulator (anneal.sim-lab). Physical simulation of the annealing process requires consideration of different heating methods for various types of specimen. One critical step is the modularisation of sections (annealing, cooling, and quenching), and their geometric arrangement. We use a design structure matrix to analyse the requirements and their structure and demonstrate a realisation in a parametric 3D-CAD model.     

Integrated system and control design of a one DoF nano-metrology platform

Mechanical vibrations and precision of conventional positioning systems are limiting factors for using nano-metrology tools directly in production environments. Vibrations cause relative motion between workpiece and inspection tool, which distorts measurements at the nanometer level. To enable robot based in-line nano-metrology, this paper proposes a metrology platform that is mounted on a robot arm and maintains a constant and precise relative distance to the workpiece by means of a control loop. This paper presents the mechatronic system design of a 1 degree of freedom (DoF) metrology platform for tracking a vibrating sample in the sub-nanometer range. By incorporating control relevant requirements in the mechanical and electrical design, which is supported by a dynamic error budgeting analysis, the implementation of a high bandwidth feedback loop is enabled. The metrology platform consists of a 1 DoF Lorentz actuator with gravity compensator, a low stiffness flexure-based guiding mechanism and a moving mass of 4 kg with high structural resonance frequencies. A high-bandwidth PD based controller that utilizes the signal of an interferometer is implemented for feedback control. Experiments show a tracking error of 4 nm RMS when exposing the sample under test to on-site measured vibrations, which complies with the dynamic error budgeting analysis. This demonstrates viability of the implemented mechatronic design for in-line metrology applications requiring sub-nanometer precision.