压电直动式气动PWM比例阀试验研究

传统的气动脉宽调制(PWM)比例阀因采用电磁铁为电 机械转换器而存在响应时间慢,稳态精度差等缺点,因而提出了一种基于压电陶瓷为电 机械转换器的新型压电直动式气动PWM比例阀的总体结构方案。研制了其实物样机,并进行了其动态特性试验研究,分析了PWM载波频率和载波幅值、比例P系数对阀动态性能的影响。与同级别气动比例阀的试验对比表明,该阀具有响应速度快和稳态精度高的特点,具有良好的工业应用前景。     

Advanced control strategy for a digital mass flow controller

Mass flow controllers are complex mechatronic devices, the design of which involves many techniques and skills in various scientific domains. Due to the slow response time of the sensors embedded in such devices, it is critically important to control gas flow variations in processes used in semiconductor industry. This paper shows how a digital controller for MFCs can be mathematically computed once the dynamic characteristics of the open-loop system have been identified. The proposed control method goes beyond prior art control methods as it explicitly takes into account the dynamics of the sensor, computes the digital controller appropriate to the order of the open-loop model and imposes a desired closed-loop transient response. The simulations performed and experimental results obtained with this new type of digital controller were very promising.     

New polarized electromagnetic actuators as integrated mechatronic components — design and application

This paper presents an overview over the computer-aided design process of mechatronic devices and systems, especially the design of electrodynamic and electromagnetic drives using modern high-energy permanent magnetic materials like NdFeB and SmCo. This paper also presents some examples of such actuators. The first example is a miniaturized pneumatic valve for industrial applications. This valve has an integrated bi-stable polarized solenoid actuator. The second example is a polarized electromagnetic valve manufactured by modern batch technologies using photo-structurable glass material. The valve seat and the actuator coils are realized using this glass material. The third example is a gripping device with compliant mechanism and planar moving coil actuator.     

Characterization of pneumatic muscles and their use for the position control of a mechatronic finger

The objective of this work is to present a methodology to construct pneumatic muscles with length sizes depending on the operation parameters such as working pressure, contraction and force and without the need of complicated mathematical models. To validate the convenience of the proposed methodology, a mechatronic finger driven by pairs of pneumatic muscles in antagonist operation reproducing similar movements to those of a human finger was developed and tested. This four-degrees-of-freedom mechatronic finger consists of a proximal phalanx with a ball-and- socket joint to allow flection-extension and adduction-abduction movements; a medial phalanx for flection-extension movements and a distal phalanx also for flection-extension movements. Inflation/deflation for each muscle is achieved by the use of proportional-type valves. To control the movement of each constituent joint the direct and inverse kinematic equations were obtained and PID-type controllers were tuned. Measurement of the angular position for each joint was obtained by the use of Hall-effect sensors. For the signal conditioning and processing a dsPIC-based, autonomous electronic board and a graphic user interface were developed to conform a portable stand-alone system. The finger presents two convenient features; functionality and anthropomorphism. Simulation tests including the kinematic model were carried out and experimental tests with the prototype were performed getting converging results. The achieved finger movements with and without a load mass were smooth and precise, justifying the convenience of using the proposed method for the dimensioning of the muscles sizes. Further work is the design of a mechatronic hand based on pneumatic fingers of this sort. By presenting and testing this methodology it is intended that this work contributes to the claim of different authors regarding the benefits of using pneumatic muscles as reliable bio-inspired actuators in applications such as orthopaedic rehabilitation equipment and in the design of wearable robotic devices for knee motions.     

Thermodynamic analysis of a mechatronic pneumatically drivenspherical joint

Jointed-member robotic devices (Arthrobots) can benefit from the pneumatic tug-and-twist technology. In particular, two crossed Twistor-pairs provide a flexural spherical joint in the form of a Twistor gimbal-drive. Previous papers have shown that the performance characteristics of both Tuggers and Twistors may be derived from a unique appropriate enthalpy function, which results in open-loop proportional control. This paper develops the Twistor enthalpy H(P, α) based upon independent volume and torque measurements, which fully accounts for pressure-dependent Twistor's stretch and Coulomb torque. This function then provides model equations for mechatronic computer-control of the final spherical joint     

Mechatronic design approach for engine management systems

Internal combustion engines with electronic management systems have developed to mechatronic systems. They basically consist of a thermodynamic process, electromechanic, hydraulic or pneumatic actuators, electronic sensors and one ore more digital control units with their specific software. In order to meet rising demands concerning drivability, emissions and consumption under the restriction of shorter development cycles, there is a rising need for modern identification methods (neural networks) and software/hardware tools (Rapid Control Prototyping (RCP), Hardware-in-the-Loop-Simulation) for the design of engine control units. In this contribution, a software/hardware environment for a mechatronic design approach for engine control systems is discussed. A dynamic engine test stand equipped with a RCP system is described which allows fast and comfortable design and testing of new control functions. Enlarged with an on-line indication system, a cylinder pressure based engine management system can be established, where the desired control settings are calculated by an upper level engine optimization. Time-variant optimization strategies for an improved exhaust-, consumption- and drivability performance were developed by means of adequate models of the engine behavior with fast neural networks.     

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.     

Methodology for design of a vibration operated valve for abrasive viscous fluids

In this paper a new ultrasonic operated valve is presented. The ultrasonic valve design was analyzed and the valve was prototyped and tested for flow control of abrasive viscous fluid. This innovative valve concept is based on controlling the friction of material by employing several friction elements along the flow direction. Abrasive particles in the viscous fluid are stopped by the force of friction when coming into contact with the friction elements. Friction is neutralized by use of vibration to break away the abrasive particles from the friction element surfaces. Several factors were considered in designing the piezoelectric valve. Factor identification was done by conducting experiments and analyzing the resulting data. Some important factors that affect the valve design were recognized to be pumping pressure, size of friction blades along the direction of flow, density of material, viscosity, amplitude of vibration, frequency of vibration, and proportion of abrasive particles in the mix. First, a method was designed for measuring the friction coefficient of the given viscous materials. A design of experiment approach was pursued in order to identify the significant parameters. A piezoelectric transducer was used, which vibrated at the resonance frequency of 20 kHz. FEM modeling was used at that stage to ensure that the resonance frequency of the designed valve matched the resonance frequency of the transducer and booster assembly that provided vibration. In order to perform proportional flow control pulse width modulation was used to control the duty cycle of the ultrasonic power transferred to the valve. A study was performed to find the best vibration characteristics.     

基于压电双晶片的气动高速开关阀研究

基于智能材料驱动的高速开关阀具有比电磁高速开关阀更好的动静态特性。针对传统悬臂梁结构压电双晶片输出力较小的缺点,该文研究了一种基于压电双晶片的气动高速开关阀,提出了一种简支梁结构固定方式。借助COMSOL对压电元件流固耦合问题进行分析,优化了阀的关键结构参数,并对样机进行了实验研究。实验结果表明,阀的工作频宽达到280 Hz,在压差0.3 MPa的条件下,最大流量为30.7 L/min。     

一种用于印刷机的压力自动气动控制系统

介绍了印刷压力控制对印刷质量的重要性,运用气动原理图从原理上重点分析了印刷头气动压力控制系统,并对其中的关键组成部分精密减压阀和电气比例阀的选型进行详细分析和计算;通过在印刷机上使用,该系统可满足印刷及精密压力控制需要。     

Design,development and control of a portable laboratory for the chili drying process study

Agricultural products such as chilies generally require drying for preservation. Traditionally, the chili drying process has been accomplished by burning fossil fuels in ovens or by open air drying. However, this process leads to severe losses in the quality and quantity of the final product. In this paper, a portable laboratory has been designed, developed and controlled using a mechatronic design philosophy in order to facilitate the chili drying process study. This portable laboratory can simulate different drying conditions under a controlled environment in order to find the best drying parameters for different kinds of chilies. Their computer based intelligence can monitor and control temperature, humidity, air flow, electric current and weight through a graphical user interface (GUI). The modeling and control technique of the system is described in detail. Simulation results using the mathematical model and experimental results under different drying conditions are presented to demonstrate the high performance of the portable laboratory and its great potential.     

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     

Comparison of MRI-Compatible Mechatronic Systems With Hydrodynamic and Pneumatic Actuation

The strong magnetic fields and limited space make it challenging to design the actuation for mechatronic systems intended to work in MRI environments. Hydraulic and pneumatic actuators can be made MRI-compatible and are promising solutions to drive robotic devices inside MRI environments. In this paper, two comparable haptic interface devices, one with hydrodynamic and another with pneumatic actuation, were developed to control one-degree-of-freedom translational movements of a user performing functional MRI (fMRI) tasks. The cylinders were made of MRI-compatible materials. Pressure sensors and control valves were placed far away from the end-effector in the scanner, connected via long transmission lines. It has been demonstrated that both manipulandum systems were MRI-compatible and yielded no artifacts to fMRI images in a 3-T scanner. Position and impedance controllers achieved passive as well as active subject movements. With the hydrodynamic system we have achieved smoother movements, higher position control accuracy, and improved robustness against force disturbances than with the pneumatic system. In contrast, the pneumatic system was back-drivable, showed faster dynamics with relatively low pressure, and allowed force control. Furthermore, it is easier to maintain and does not cause hygienic problems after leakages. In general, pneumatic actuation is more favorable for fast or force-controlled MRI-compatible applications, whereas hydrodynamic actuation is recommended for applications that require higher position accuracy, or slow and smooth movements.     

Fractional order control to the electro-hydraulic system in insulator fatigue test device

In this paper, a special composite hydraulic cylinder, which includes two pistons and three working chambers, is proposed for driving the insulator fatigue test device. In this force loading system, a servo valve and a proportional pressure valve are used to control the composite hydraulic cylinder to generate alternating force and fixed force respectively. Furthermore, the models of the electro-hydraulic system are built and its dynamic characteristic is analyzed based on the models. Considering the uncertainty of the model parameters, the fractional order proportional-integral-derivative controller is adopted to control the two valves. The Oustaloup method is used to discrete the fractional order controller and the iteration feedback tuning method is presented to tune the controller parameters. The tuning process which is independent on the system model can be done on the close loop system. Simulation and experimental results have shown that the fractional order controller is effective.     

Modeling and design methodology for mechatronic systems

The integration of mechanical systems and microelectronics opens many new possibilities for process design and automatic functions. After discussing the mutual interrelations between the design of the mechanical system and digital electronic system the different ways of integration within mechatronic systems and the resulting properties are described. The information processing can be organized in multi levels, ranging from low level control through supervision to general process management. In connection with knowledge bases and inference mechanisms, intelligent control systems result. The design of control systems for mechanical systems is described, from modeling, identification to adaptive control for nonlinear systems. This is followed by solving supervision tasks with fault diagnosis. Then design tools for mechatronic systems are considered and examples of applications are given, like adaptive control of electromagnetic and pneumatic actuators, adaptive semiactive shock absorbers for vehicle suspension, and electronic drive-chain damping.     

Design and hybrid control of the pneumatic force-feedback systems for Arm-Exoskeleton by using on/off valve

This article models a pneumatic force-feedback system consisting of the double-acting cylinder and a set of high-speed on–off valves, and its fuzzy controller in order to provide an insight into pneumatic system design and force-feedback control requirements of the Arm-Exoskeleton, which is applied in robot-teleoperation and robotics. In modeling, effects of nonlinear flow through the valves, air compressibility in cylinder chambers, and time delay and attenuation of the pressure input in the connecting tubes are considered. Based on this mathematical model, the hybrid fuzzy control method for the precise force-feedback control is proposed and the fuzzy controllers are realized with the Mega8 MCUs as the units of the distributed control system in the Arm-Exoskeleton. At last a series of experiments validated the models and control method.     

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.     

Modeling and control of a novel pneumatic two-stage piezoelectric-actuated valve

In manufacturing automation, there is a strong need for highly integrated intelligent components and subsystems. In this context, a novel two-stage pneumatic piezoelectric-actuated valve has recently been developed. It covers a wide range of pneumatic products and functions in one compact component and enables flexible and adaptive plant operation. The valve consists of four poppet main-stage valves that are driven by piezoelectrically actuated pre-stage valves and includes pressure sensors as well as a powerful computational unit. This work presents the systematic development of a model-based position control algorithm including modeling, identification, and controller design. The control concept comprises a hysteresis compensation based on the Prandtl–Ishlinskii operator theory, a flatness-based feedforward controller, and a PI feedback controller with appropriate anti-windup measures. Measurement results from a test bench demonstrate the performance of the proposed concept.