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.     

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     

A mechatronic approach to microsystem design

This paper discusses the implementation of a concurrent-engineering view of microsystem design. The proposed concurrent-engineering or mechatronic approach to the design of hybrid microsystems is illustrated by three case studies. First, the design of an advanced computer writing tool is discussed. The design of this consumer product requires a mechatronic approach at different functional levels and at different levels of miniaturization. Another illustration of this approach is the design of an implantable drug delivery device. A device for solid drug delivery, as well as a device for liquid drug delivery, are presented. It is demonstrated that miniaturization can be obtained by a combination of functions in a single component. The multiplication of functions in a single component automatically leads to a concurrent-engineering approach far the design. Finally, the micromanufacturing of silicon parts by electrodischarge machining is described. It is demonstrated that electrodischarge machining of silicon is not only feasible, but forms an interesting and complementary technology to traditional silicon micromachining. Therefore, this powerful manufacturing technique opens the way for concurrent engineering of real three-dimensional micromechanical sensors and actuators with integrated processing electronics on the same wafer     

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.     

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.     

Integral resonant control for suppression of resonance in piezoelectric micro-actuator used in precision servomechanism

Micro-actuators are widely used nowadays in mechatronic systems that demand ultra-fine precision and accuracy in positioning the object to be controlled. A large bandwidth is required as well to achieve such performance. The resonant modes of the micro-actuator would be one of the major obstacles in the path to achieving such a necessary high bandwidth. The servo designer must have the resonant vibrations suppressed in order to set the necessary bandwidth target sufficiently high so that the necessary precision requirements are met. The conventional approach is to use a notch filter in cascade with the actuator to provide high attenuation at frequencies of these resonances. In this paper, we present an improved alternative approach using a feedback compensator, designed based on the principle of ‘integral resonant control’, for attenuating resonances of a piezoelectric micro-actuator. Here, the effectiveness of the design is underscored through simulation and experimental verification.     

An integrated mechatronic approach for the systematic design of force fields and programming of microactuator arrays for micropart manipulation

Micromanipulation is a hot topic in the rapidly emerging area of micromechatronics and particularly in the manufacturing and assembling of micromechatronic products. This paper introduces an integrated mechatronic approach for the systematic design and operation of flexible, sensorless, automated micromanipulation for a variety of microparts on microactuation arrays. This approach is a mechatronic synthesis of methods from different engineering areas such as solid modeling, electronics design, software for control and programming of mechanical actuation. It involves designing of programmable force fields for manipulation of convex or non-convex polygonal microparts on an array, hardware programmable circuitry for the activation of the array and a software algorithmic procedure for the programming. A detailed analysis is given, as well as several simulated experiments performed using the introduced approach on a cilia microactuator array for a variety of polygonal asymmetric and non-convex microparts and the results are presented and discussed. Finally, the advantages and limitations of this approach are analyzed and points for further research are raised.     

An example of design—Embodiment for electrorheological fluid based mechatronic transmission components

In this paper some design concept for mechatronic components used in transmission systems with ER fluid based on the testing of physical models is proposed. The proposed design concept of mechatronic components of a transmission system was used to control a viscous brake where application of various ER fluids was considered in order to vary its performance. The main problem was to investigate whether changes of rheological characteristics due to the application of different fluids correspond to changes of torque carried by the brake throughout the entire range of angular velocities.Based on the brake testing results it was concluded that the results obtained for one working fluid could be successfully used for the design of a brake with an ER fluid having different rheological characteristics.     

一种新的连续值反馈闭环拥塞控制方案的设计及性能分析

本文提出并分析了一种连续值反馈闭环拥塞控制方案。证明了它的无振荡稳定性,推导出使得系统性能达到最佳的参数设置。所谓最佳是指：系统达到稳定的速度很快;稳态下,系统的带宽利用率最大,并且延迟最小。文中的仿真结果表明,该方案在各种情况下运行正常,且性能优于其它的一些连续反馈控制方案。     

Toward a unified and automated design methodology for multi-domain dynamic systems using bond graphs and genetic programming

This paper suggests a unified and automated design methodology for synthesizing designs for multi-domain systems, such as mechatronic systems. A multi-domain dynamic system includes a mixture of electrical, mechanical, hydraulic, pneumatic, and/or thermal components, making it difficult use a single design tool to design a system to meet specified performance goals. The multi-domain design approach is not only efficient for mixed-domain problems, but is also useful for addressing separate single-domain design problems with a single tool. Bond graphs (BGs) are domain independent, allow free composition, and are efficient for classification and analysis of models, allowing rapid determination of various types of acceptability or feasibility of candidate designs. This can sharply reduce the time needed for analysis of designs that are infeasible or otherwise unattractive. Genetic programming is well recognized as a powerful tool for open-ended search. The combination of these two powerful methods is therefore an appropriate target for a better system for synthesis of complex multi-domain systems. The approach described here will evolve new designs (represented as BGs) with ever-improving performance, in an iterative loop of synthesis, analysis, and feedback to the synthesis process. The suggested design methodology has been applied here to three design examples. The first is a domain-independent eigenvalue placement design problem that is tested for some sample target sets of eigenvalues. The second is in the electrical domain––design of analog filters to achieve specified performance over a given frequency range. The third is in the electromechanical domain––redesign of a printer drive system to obtain desirable steady-state position of a rotational load.     

Observer-corrector control design for robots with destabilizing unmodeled dynamics

Industrial robotic manipulators and other mechatronic systems often possess undesirable higher order dynamics exhibited in the form of resonance conditions which affect closed-loop stability when feedback control is applied. In this study, an alternative reduced-complexity control design strategy is presented. The fundamental idea of the proposed approach is to synthesize a substitute feedback signal which reflects the dominant dynamics essential for operation of the system subject to control but does not include the undesirable higher order dynamic effects. A unique arrangement of a band-limited state observer and a low-pass filter corrector is employed for this purpose, providing a mechanism to extract the dominant dynamics from the output of the system with minimal amplitude and phase distortion. The resulting synthetic signal is used as a controller input, effectively eliminating destabilizing effects of the undesirable higher order dynamics. As a result, the controller can be designed practically without taking the higher order dynamic effects into account, which allows for use of conventional control techniques, and translates into reduced modeling requirements, simplified controller design and shorter development time when compared to a complete dynamic analysis. The effectiveness of the proposed concept is demonstrated experimentally on motion control of a four-axis direct-drive robotic manipulator for automated pick-place operations in semiconductor manufacturing applications. It is concluded that the proposed control design strategy provides improved control performance, increased stability margin, and added robustness against variations in system parameters in comparison to common methods adopted currently in the engineering practice.     

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.      

Optimal design of ball-screw driven servomechanisms through an integrated mechatronic approach

This paper proposes a novel model-based mechatronic approach for the design of ball-screw driven servomechanisms. The proposed technique is aimed at selecting the optimal combination of electric motor and ball-screw which minimizes the motor torque, while ensuring the achievement of the prescribed dynamic performances of the closed loop system. Such performances, as well as feasibility constraints related to the component characteristics, are translated in the method as bounds in the lead – diameter space. In particular, feasible torque and speed are the constraints posed by the motor; screw critical speed, ball critical speed, service life, buckling load are those due to the ball-screw, while the controlled system performances are included through the inertia ratio and the bandwidth requirements. To this purpose, the ball-screw non-ideal characteristics are represented through models with different complexity and are accounted for in the design. A straightforward graphical approach is formulated to trade off between the many conflicting requirements and to prevent both overly conservative and undersized design, while ensuring problem solvability.     

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.     

Development and implementation of an FPGA based fractional order controller for a DC motor

Fractional calculus has been gaining more and more popularity in control engineering in numerous fields, including mechatronic applications. One of the most common applications in all mechatronic domains is the control of DC motors. Several control algorithms have been proposed for such motors, ranging from traditional PID algorithms, to the more sophisticated advanced methods, including fractional order controllers. Nevertheless, very little information regarding the implementation problems of such fractional algorithms exists today. The paper proposes a simple approach for designing a fractional order PI controller for controlling the speed of a DC motor. The resulting controller is implemented on an FPGA target and its performance is compared to other possible benchmarks. The experimental results show the efficiency of the designed fractional order PI controller. Beside the initial DC motor, two other different DC motors are also used in the experiments to demonstrate the robustness of the controller.     

Analytical computation of the energy-efficient optimal planning in rest-to-rest motion of constant inertia systems

Among the techniques to improve energy efficiency of mechatronic systems, the synthesis of optimized motion profiles has been proved to be an effective and almost costless method. In order to boost the use of this approach, this paper proposes an analytical method for improving energy efficiency in rest-to-rest motion through optimal planning, by selecting both the optimal motion law and the optimal motion time (duration). The proposed technique is suitable for constant inertia systems. As a matter of fact, this kind of mechatronic systems covers a wide range of applications in production, packaging or logistic plants.The method practical application is straightforward, since it just relies on the knowledge of the task specifications and of some system parameters to compute the optimal motion time for each selected trajectory and to compare analytically different motion profiles. The limitations due the servo-actuator (torque, speed, bandwidth), to machine throughput requirements, as well as the smoothness specifications (acceleration and jerk limitations, degree of continuity) are explicitly accounted for through bounds, to ensure the feasibility of the motion profiles developed.Since the proposed method proposes an analytical algebraic equation, it does not require either time-consuming simulations and trial-and-error evaluations, or numerical optimizations. Hence, it is well suited for industrial mechatronic applications.