Extremum seeking control for soft landing of an electromechanical valve actuator

Many electromagnetic actuators suffer from high velocity impacts. One such actuator is the electromechanical valve actuator, recently receiving attention for enabling variable valve timing in internal combustion engines. Impacts experienced by the actuator are excessively loud and create unnecessary wear. This paper presents an extremum seeking controller designed to reduce the magnitude of these impacts. Based on a measure of the sound intensity at impact, the controller tunes a nonlinear feedback to achieve impact velocities of less than while maintaining transition times of less than . The control strategy is implemented with an eddy current sensor, to measure the valve position, and a microphone.     

The electromechanical response of a symmetric electret parallel-plates actuator

The electromechanical response of a symmetric electret parallel-plates actuator is analyzed. The actuator is constructed from a dielectric plate that is suspended by a linear spring between two electrodes of a planar capacitor. The dielectric plate is loaded with fixed charge, and is displaced due to the interaction between this charge and the electrostatic field. The electrostatic field that displaces the charged dielectric has three components: a field induced by the voltage difference across the capacitor plates, a field induced by the anti-symmetric part of charge, and a field induced by the combined effect of the symmetric part of charge and the displacement of the plate itself. The analysis shows that the displacement of the electret actuator is a linear function of the driving voltage, and that a full range of stable motion can be achieved. Furthermore, it is shown that all important characteristics of the fixed charge can be deduced from simple measurements.     

电动舵机的复合自适应非奇异终端滑模控制

非奇异终端滑模控制（NTSMc）能够实现误差的有限时间收敛,但一般NTSMC的控制律采用高增益项来消除系统不确定性的影响,具有较强的保守性．为了降低这种保守性,本文采用复合白适应律对系统的不确定参数进行估计,按照估计值设计复合自适应非奇异终端滑模控制（CANTSMC）,对不确定参数引起的系统动态进行补偿．本方案曾经应用于电动舵机,以补偿不确定参数对模型动态性能的影响．本文证明了闭环稳定性,以及输出跟踪误差在有限时间内的收敛性．通过仿真验证了该方法的有效性．     

The design optimization of the electromechanical actuator

This paper describes the design optimization of a flat-faced disk type of an electromagnet. In order to minimize volume and power dissipation, expressions for consumed power, magnetic attraction force, coil temperature and magnet volume have been obtained, depending on the dimensions. The sequential quadratic programming (SQP) method has been employed to solve the nonlinear optimization problem, and the different optimum solutions have been obtained to emphasize the significance of alterations in the temperature and power consumption. It has been showed that volume minimization has been improved about 25% compared to direct computation and, by the minimisation of power consumption, static characteristic of the magnet has been improved about 20%.     

Design and characterization of a multi-stable magnetic shape memory alloy hybrid actuator

This paper describes the design and the characterization of a multi-stable hybrid actuator composed of a single magnetic shape memory alloy element and an electromagnetic actuator. The series arrangement of the active material and the electromagnetic actuator allows a new shape of hysteresis curve and a precise positioning can be obtained. The design of the different magnetic circuits has been done by analytic and numeric simulations in MatLab and FEMM 4.2. This study gives results of the elongation, the blocking force, and the holding force that can be obtained with such an actuator. Strokes up to 0.35 mm and a blocking force of 2.6 N have been measured for the hybrid actuator using a magnetic shape memory alloy with a cross section of 2.5 mm². Such an actuator can find application in precise positioning and medium frequency actuation systems. Nevertheless, there is much design space for improvements in terms of energy consumption, heat transfer, and overall cost of the device.     

Design of a hybrid optical image stabilization actuator to compensate for hand trembling

In this paper, a novel hybrid optical image stabilization (OIS) actuator for digital camcorder is proposed. Image stabilization for this hybrid type consists of both radially and tangentially moving components to compensate for hand trembling. The proposed OIS actuator, which uses a voice coil motor method, is divided into two parts: a structure and a magnetic circuit. For the structural part, the driving mechanism consists of two systems: one system is based on a ball guide with a magnetic spring, and the other system is based on a pivot bearing. The former system is typically used as a driving mechanism in mobile devices, whereas the latter system has advantages such as mechanical stability and reduced friction. Overall, a magnetic spring between the magnet and yoke should be considered to select the best magnetic circuit part design and mechanism design. Regarding the electro-magnetic (EM) circuit, two types of EM circuits were designed to satisfy each direction: one circuit is a moving magnet circuit for the radial direction, and the other circuit is a moving coil for the tangential direction. In a digital camcorder, the space for the OIS actuator is limited, and thus, optimized actuator with adequate performances is required. To solve these problems, a sensitivity analysis was performed using the design of experiment procedure. Based on these results, an objective function was defined for the optimization procedure. Finally, the actuator was fabricated, and the dynamic characteristics and feasibility of adapting two types of mechanisms of the suggested OIS actuator were verified. The experimental results indicate that the proposed OIS actuator exhibits sufficient performance for the sensitivity.     

Intelligent control of DC motor driven electromechanical fin actuator

In this paper modeling, simulation and control of an electromechanical actuator (EMA) system for aerofin control (AFC) with permanent magnet brush DC motor driven by a constant current driver are investigated. Nonlinear model of the EMA-AFC system has been developed and experimentally verified in actuator test bench. Model has been used as the starting point for PID position controller synthesis. To improve performances of the system, computational intelligence has been applied. Genetic PID optimization, genetic algorithm (GA) optimized fuzzy supervisory PID control and finally GA optimized nonlinear PID algorithm modification are proposed. Improved transient response and system behavior have also been experimentally validated.     

基于DSP的主动光学力促动器控制系统设计

针对步进电机型力促动器,设计了一种基于DSP的力促动器控制系统,并进行了测试.系统以TMS320F28069型DSP作为主控制器,采用ADS1259高精度A/D转换器采集传感器LoadCell输出力信号,通过DSP片上PWM模块输出电机控制脉冲给电机细分驱动芯片TMC389,驱动步进电机转动,形成力控制闭环.系统软件采用PID控制算法来校正力促动器输出偏差,并给出了控制程序流程图.实验测试结果表明:该控制系统具有良好的响应特性和较强的抗干扰能力,满足主动光学实验系统的要求.     

机电作动器悬架硬件在环仿真测试平台研究

为了提高汽车的平顺性,提出一种机电作动器悬架,设计了机电作动器悬架硬件在环仿真测试平台。建立基于机电作动器的主动悬架数学模型与仿真模型,以嵌入式系统单片机为主处理器设计机电作动器悬架的控制器;在此基础上,以dSPACE为模型运行载体搭建机电作动器悬架硬件在环仿真测试平台;利用该测试平台进行了仿真试验。结果表明所研究的硬件在环仿真测试平台具备较好的硬件在环仿真功能,能够对机电作动器悬架性能、主动悬架控制算法进行验证与评价。     

Design principle of micromechanical probe with an electrostatic actuator for friction force microscopy

It is important to understand friction force in micro/nano mechanical devices both at high sliding speed and with high lateral resolution. Dual-axis friction force microscopes that can provide high lateral resolution and accuracy have been proposed; however, the sliding speed is limited by the probe scan speed. While a micro mechanical probe (MMP) with an electrostatic actuator can overcome this problem, details of probe design have not been established yet. This paper presents the principle of the mechanical design for an MMP with high force sensitivity and sufficient drive force. The dimensions of the double cantilever beam control the spring constants, resonant frequencies, and drive force. The use of an actuated MMP enables accurate friction force microscopy at high sliding speeds, which is required for the design of micro/nano mechanical devices.     

Design and experimental evaluation of a robust force controller for an electro-hydraulic actuator via quantitative feedback theory

This paper presents the design and experimental evaluation of an explicit force controller for a hydraulic actuator in the presence of significant system uncertainties and nonlinearities. The nonlinear version of quantitative feedback theory (QFT) is employed to design a robust time-invariant controller. Two approaches are developed to identify linear time-invariant equivalent model that can precisely represent the nonlinear plant, operating over a wide range. The first approach is based on experimental input–output measurements, obtained directly from the actual system. The second approach is model-based, and utilizes the general nonlinear mathematical model of a hydraulic actuator interacting with an uncertain environment. Given the equivalent models, a controller is then designed to satisfy a priori specified tracking and stability specifications. The controller enjoys the simplicity of fixed-gain controllers while exhibiting robustness. Experimental tests are performed on a hydraulic actuator equipped with a low-cost proportional valve. The results show that the compensated system is not sensitive to the variation of parameters such as environmental stiffness or supply pressure and can equally work well for various set-point forces.     

Design and fabrication of a hybrid silicon three-axial force sensor for biomechanical applications

This paper presents the design and development of a silicon-based three-axial force sensor to be used in a flexible smart interface for biomechanical measurements. Normal and shear forces are detected by combining responses from four piezoresistors obtained by ion implantation in a high aspect-ratio cross-shape flexible element equipped with a 525 μm high silicon mesa. The mesa is obtained by a subtractive dry etching process of the whole handle layer of an SOI wafer. Piezoresistor size ranges between 6 and 10 μm in width, and between 30 and 50 μm in length. The sensor configuration follows a hybrid integration approach for interconnection and for future electronic circuitry system integration. The sensor ability to measure both normal and shear forces with high linearity (99%) and low hysteresis is demonstrated by means of tests performed by applying forces from 0 to 2 N. In this paper the packaging design is also presented and materials for flexible sensor array preliminary assembly are described.     

Diagnosis of process valve actuator faults using a multilayer neural network

This paper investigates the ability of a multilayer neural network to diagnose actuator faults in a Fisher-Rosemount 667 process control valve. A software package that comes with the valve is used to obtain experimental figures of merit related to the position response of the valve given a step command. The particular values of the dead time, peak time, percent overshoot, steady state error, 63% and 86% rise times, and gain are shown to depend on the severity of three commonly occurring faults: incorrect supply pressure, actuator vent blockage, and diaphragm leakage. The relationships between these parameters form fault signatures for each operating condition that are subsequently learned by a multilayer feedforward neural network. The results show that the trained network has the capability to detect and identify various magnitudes of the faults of interest. In addition, it is observed that the network has the ability to estimate fault levels not seen by the network during training. The approach presented in this paper allows the existing instrumentation to be utilised without modification. Thus, the proposed methodology is practical to implement.     

Modelling,simulation and identification of an engine air path electromechanical actuator

This paper deals with the modelling and the identification of an electromechanical Diesel engine actuator. The studied Bosch GPA-S actuator is designed for swirl/tumble flaps to control the air amount entering into the cylinder. This study aims to design a complete simulator that reproduces, with sufficient accuracy, the actuator dynamics taking into account the effects of the friction phenomenon. Hence, an overview of the actuator structure and its operation principle is first given. Then, its mathematical model as well as the nonlinearity, related to its behaviour, is discussed. Next, three identification procedures, which allow estimating both the system parameters and the friction model coefficients, are introduced. Finally, simulation results, using MATLAB, and experimental results, using LabVIEW, are presented demonstrating the effectiveness of the proposed techniques.     

Shaped comb fingers for tailored electromechanical restoring force

Electrostatic comb drives are widely used in microelectromechanical devices. These comb drives often employ rectangular fingers which produce a stable, constant force output as they engage. This paper explores the use of shapes other than the common rectangular fingers. Such shaped comb fingers allow customized force-displacement response for a variety of applications. In order to simplify analysis and design of shaped fingers, a simple model is developed to predict the force generated by shaped comb fingers. This model is tested using numerical simulation on several different sample shaped comb designs. Finally, the model is further tested, and the use of shaped comb fingers is demonstrated, through the design, fabrication, and testing of tunable resonators which allow both up and down shifts of the resonant frequency. The simulation and testing results demonstrate the usefulness and accuracy of the simple model. Finally, other applications for shaped comb fingers are described, including tunable sensors, low-voltage actuators, multistable actuators, or actuators with linear voltage-displacement behavior.     

Grasping impact force control of a flexible robotic gripper using a piezoelectric actuator

This paper presents robust force tracking control of a flexible beam during a grasping operation using a piezoceramic actuator. Equations describing the motion of the gripper in conditions of contact and noncontact are derived based on the cantilever beam. In this study, contact force is regulated, in addition to the impact force generated at the instant of contact, based on variable structure model reference adaptive control theory using only force measurements. For the derivation of the control law, it is assumed that parameters of the beam and the stiffness of the object are unknown. Computer simulations show the effectiveness the controller. This work was presented, in part, at the Fourth International Symposium on Artificial Life and Robotics, Oita, Japan, January 19–22, 1999     

Observer-based backstepping force control of an electrohydraulic actuator

A backstepping approach is used in this paper to design a nonlinear controller for force control of a single-rod electrohydraulic actuator. The control design guarantees the convergence of the tracking error. The implementation of the control design requires system states for feedback, but in this case only the force output is available. To overcome this problem, a PI observer is used to estimate the states of the system. Experimental results have illustrated the success of the observer-based backstepping controller. The results are also compared to those obtained with conventional P and PI controllers. It can be shown that the observer-based backstepping controller has a relatively better tracking performance.     

Design of a magnetostrictive (MS) actuator

Several advanced technologies are introduced in automotive applications. Higher energy density and dynamic performance are demanding new and cost-effective actuator structures. Magnetostriction (MS), change in shape of materials under the influence of an external magnetic field, is one of the advanced technologies. Good understanding of specific design constrains is required to define and optimize a magnetostrictive actuator. This paper presents parametrical analysis with magnetic simulation of a magnetostrictive actuator. Proposed actuator has been designed, and the performance has been evaluated on experimental rig. Strain, elongation of the shaft, of 1000 ppm at 10 A and a blocked force over 4500 N has been achieved with shaft of 8 mm diameter, made of Terfenol-D. Furthermore, the effect of pre-stress of the Terfenol-D shaft has been evaluated experimentally. The study shows that excellent features can be obtained by magnetostrictive materials for many advanced applications.     

Design and modeling of a novel electromechanical optical micro-scanner

Microsystem Technologies - This article presents a design principle of a novel small-sized compliant optical micro-scanner with two translational (X, Y) and a rotational (θz) degree of...     

Stacked dielectric elastomer actuator for tensile force transmission

This paper presents a novel approach for active structures driven by soft dielectric electro-active polymers (EAPs), which can perform contractive displacements at external tensile load. The active structure is composed of an array of equal segments, where the dielectric films are arranged in a pile-up configuration. The proposed active structure has the capability of exhibiting uniaxial contractive deformations, while being exposed to external tensile forces. The serial arrangement of active segments has one contracting degree of freedom in the thickness direction of the dielectric EAP film layers.Due to the envisaged tension force transmission capability, special attention is paid to the electrode design which is of paramount importance with regard to functionality of the actuator. A compliant electrode system with anisotropic deformation properties is presented based on nano scale carbon powder. In experiments, the free deformation as well as the contractive motion under external tensile loading of several actuator configurations with different setups is characterized. These involve the study of various sizes and numbers of stacked film layers as well as different electrode designs.