Enhanced locomotive and drilling microrobot using precessional and gradient magnetic field

We propose a new electromagnetic actuation (EMA) system for an intravascular microrobot with steering, locomotion and drilling functions. The EMA system consists of 3 pairs of Helmholtz coil and 1 pair of Maxwell coil. Generally, Helmholtz coils can align a microrobot in a desired direction by generating a uniform magnetic flux. If the uniform magnetic field generated by Helmholtz coils can be rotated, a microrobot with Helmholtz coils can also be rotated. On the other hand, a Maxwell coil, which generates a constant gradient magnetic flux, can supply the propulsion force for the microrobot. A microrobot actuated by the proposed EMA system has a spiral shaped body containing two magnets with different magnetization directions. With the proposed EMA system, the microrobot can move to the target region and perform drilling there by the precessional magnetic field of the Helmholtz coil pairs. The propulsion force for the microrobot is produced by the gradient magnetic field generated by the Maxwell coil pair. The moving velocity and the drilling performance of the microrobot can be increased by the propulsion force of the Maxwell coil pair. Through various tests, the feasibility and enhancement of the microrobot actuated by the proposed EMA system were verified.     

Novel electromagnetic actuation (EMA) method for 3-dimensional locomotion of intravascular microrobot

A new electromagnetic actuation (EMA) method is proposed for 3-dimensional locomotion of a microrobot. Generally, the EMA system uses Helmholtz coils and Maxwell coils. The Helmholtz coil pair generates a uniform magnetic flux density and the Maxwell coil pair generates a uniform gradient magnetic flux. The microrobot can be aligned to the desired direction by the Helmholtz coils and then, be propelled in the aligned direction by the Maxwell coils. However, many previous EMA systems have been restricted to 2-dimensional planar actuation. The EMA system proposed in this paper consists of a pair of stationary Helmholtz–Maxwell coils and a pair of rotational Helmholtz–Maxwell coils. This new EMA system can manipulate a microrobot in 3-dimensional space. For accurate actuation of a microrobot, the gravitational force, which influences the motion of microrobot, has to be analyzed and compensated. Through various experiments, the performance of the proposed EMA system was evaluated. Finally, a microrobot was test-driven in a blood vessel phantom, and the result of the test drive verified the feasibility of 3-dimensional motion of a microrobot by the new EMA system.     

Preview control of web position in roll-to-roll printing using alignment patterns

In printed electronics systems, the roll-to-roll process is a next-generation process technology that may be applied to the production of various electronic products such as flexible electronic devices, solar cells, and display panels. The process allows for production at low unit cost and high speed. As a factor for improving the print quality, there are ink viscosity, printing speed, printing pressure, and alignment precision. Among these factors, alignment precision, a critical factor in the performance of an electronic circuit, is the accurate alignment of layers in a multi-layered structure. In our previous study, we suggested a measurement method for improving the alignment precision by using an optical pre-measuring device and an alignment pattern that is printed by roll-to-roll printing process. In the measuring system, when a web is transported in the web feed direction, the optical pre-measuring device measures the quantity of light reflected by the alignment pattern. A lateral position can be aligned accurately based on the measured signal. However, because the position is measured in advance in the web feed direction, it is not applicable to a real-time printing system, and when the lateral position is measured using the optical pre-measuring device, a lateral position error, that is generated by disturbances induced by tension acting on the web and the vibration of the motor, can be estimated. A motor driven linear translation stage for lateral direction is used to minimize the lateral position errors in roll-to-roll systems. In this paper, we propose a preview control system to reflect the measured lateral position error to the printing result at the appropriate time for improving the alignment precision in roll-to-roll printing. As a control method, using roll-to-roll model, the system of disturbance, lateral angle and lateral position can be expressed as a state-space equation. Based on this equation, a preview controller to find the optimal value of state and control error is designed in a similar method to the conventional preview control method used for the active suspension system of a vehicle. Then, the alignment results are verified using another optical measuring device of a web transport system.

     

旋转磁矢量场发生器研究

为了在实验室环境下对飞行器滚转角测量装置进行调试,研究了一种旋转磁矢量场模拟试验装置;采用ANSYS软件对磁屏蔽筒的屏蔽效应及亥姆霍兹线圈的磁场分布进行了数值模拟,并采用TMS320F2809-100型DSP芯片和TIDSPBIOS实时操作系统实现矢量信号的发生;结果表明:磁屏蔽筒能有效屏蔽外界磁场,产生近似的零磁空间;亥姆霍兹线圈中心区域磁感强度为变化缓慢的均匀区,可作为被测装置的工作区;测量数据与模拟器输出信号的理论值的差值小于6%,DSP的CPU运算能力裕度大于50%;用磁屏蔽筒、亥姆霍兹线圈、矢量信号发生器可以构成用于飞行器滚转角测量的模拟实验装置。     

一种用于生物效应研究的电磁场发生装置

本文介绍了一种磁场参数可调的磁场发生器,它由振荡器、二阶系统、计数器、译码器、功率电路、亥姆霍兹线圈等组成。该装置主要用于生物效应研究,文中阐述了如何通过调节二阶系统的参数来调节亥姆霍兹线圈产生磁场强度和频率,其工作频率1～325kHz、场强≤200Gs,理论计算值与实际偏差在15%之内。     

Design and Control of a Four‐Wheeled Omnidirectional Mobile Robot with Steerable Omnidirectional Wheels

Omnidirectional mobile robots are capable of arbitrary motion in an arbitrary direction without changing the direction of wheels, because they can perform 3 degree‐of‐freedom (DOF) motion on a two‐dimensional plane. In this research, a new class of omnidirectional mobile robot is proposed. Since it has synchronously steerable omnidirectional wheels, it is called an omnidirectional mobile robot with steerable omnidirectional wheels (OMR‐SOW). It has 3 DOFs in motion and one DOF in steering. One steering DOF can function as a continuously variable transmission (CVT). CVT of the OMR‐SOW increases the range of velocity ratio from the wheel velocities to robot velocity, which may improve performance of the mobile robot. The OMR‐SOW with four omnidirectional wheels has been developed in this research. Kinematics and dynamics of this robot will be analyzed in detail. Various tests have been conducted to demonstrate the validity and feasibility of the proposed mechanism and control algorithm. © 2004 Wiley Periodicals, Inc.     

杆臂效应与挠曲变形一体化误差补偿技术研究

针对舰载机捷联惯导系统（Strapdown Inertial Navigation System,SINS）传递对准技术中存在挠性杆臂效应问题,提出一种采用误差模型一体化的补偿方案。建立了杆臂效应与挠曲变形的一体化误差模型,分析了线性量测方程下的简化非线性卡尔曼滤波（Unscented Kalman Filter,UKF）算法,将其应用在杆臂效应与挠曲变形的一体化误差补偿技术中。模拟海浪干扰下舰船的三轴摇摆动态仿真环境,利用仿真结果验证了一体化误差补偿方案可行性。     

微创血管介入手术机器人的主从交互控制方法与实现

微创血管介入手术是治疗冠心病的重要治疗手段, 手术中要求对导管、导丝等介入器械高精度递送.得益于机器人技术的高精度、可远程操作等特点, 血管介入手术机器人的研制受到了极大关注.在微创血管介入手术中, 按导管或导丝远端所处血管部位, 将介入器械递送过程分为三个阶段: 1) 主动脉阶段:导丝或导管远端位于主动脉, 需快速前送, 以减少X射线和造影剂的使用; 2) 冠脉入口阶段:导丝或导管远端进入冠脉, 此时需选择相应的病变冠脉分支; 3) 冠脉病变阶段:导丝或导管远端位于狭窄病变部位, 需要高精度操作才能使导丝或导管穿过狭窄病变.针对器械递送的不同阶段, 提出具有运动缩放的主从控制方法, 通过改变血管介入手术机器人主端和从端之间的运动缩放关系, 实现机器人从端对主端操作的放大、缩小或等比例复现.通过在微创血管介入手术机器人平台实验, 验证了机器人从端对主端操作缩放的可行性和有效性.通过操作时间和操作精度对比分析得到:在缩放因子为4时操作时间减少39.9%;在缩放因子为1/4时, 平移和旋转操作精度分别提高72.9%和77.1%.     

Wideband beam‐steerable configuration of metasurface loaded slot antenna

In this article, a wideband two dimensional (2D) beam‐steerable antenna structure is presented. The proposed structure is based on a radially gradient hybrid metasurface (RGHMS) illuminated through a slot antenna. The half aperture of the RGHMS comprises of a gradient phase profile topology, while its other half aperture consists of a constant phase profile configuration. The slot antenna possessing the bidirectional radiation pattern is printed on a relatively thin substrate, which operates over a wide bandwidth of 1420 MHz (15.10%). The placement of RGHMS tilts the main beam of slot antenna by 15° away from normal direction. Further, in‐plane movement of MS provides beam steering in both elevation and azimuth planes, with a conical region of an apex angle of 30°. Apart from the beam steering capability, the placement of RGHMS in front of slot antenna also enhances the overall bandwidth and gain by 360 MHz and 5 dB, respectively. Thus, a wide band beam steering configuration with the impedance bandwidth of 1780 MHz (18.85%) is obtained. In order to investigate the frequency dependent beam tilting capability of the RGHMS in the elevation plane, a detailed analysis is carried out using the principle of refraction.     

Robust control of robots via linear estimated state feedback

In this note we propose a robust tracking controller for robots that requires only position measurements. The controller consists of two parts: a linear observer part that generates an estimated error state from the error on the joint position and a linear feedback part that utilizes this estimated state. It is shown that this computationally efficient controller yields semi-global uniform ultimate boundedness of the tracking error. An interesting feature of the controller is that it straightforwardly extends results on robust control of robots by linear state feedback to linear estimated-state feedback     

车轮定位参数微辅助测量系统

介绍一种新型汽车车轮定位参数的微机测量系统。该系统采用8031单片微机为主机，可完成车轮定位参数、转向轮最大转角、方向盘转角范围及自由行程的自动测量及显示、打印输出；绘制阿克曼特性曲线和转向系角传动比特性曲线，还可对轮辋及夹角“摆差”进行自动补偿。     

一种新型混合磁浮系统研究

本文通过分析永磁与常导、高温超导与常导混合磁浮系统，以及纯超导吸力悬浮方案的局限性，结合二者优点提出一种新的混合悬浮方案——高温超导与永磁混合悬浮系统，建立其悬浮模型，探讨系统的PID控制原理，通过仿真分析了系统的稳定性和优点。     

An innovative micro-diamagnetic levitation system with coils applied in micro-gyroscope

This paper presents design, simulation, and fabrication, levitation experiment of a micro-diamagnetic levitation system with coils. This micro-system module can be applied in the micro-gyroscope system because of its stable levitation of disc. The device configuration consists of three main parts: micro-disc, stator and permanent magnet (PM). Micro-disc is stably levitated on the top of the stator and PMs due to stable diamagnetic force produced between PMs and pyrolytic graphite disc. Simulation on levitation shows the situation of diamagnetic force at the centre, and offset from centre. Finally, from the levitation experiment we can see clearly the influence on levitation height of PM thickness and micro-disc thickness. As far as micro-gyroscope is concerned, coils analysis shows relationship between rotation torque and current frequency by Ansoft Maxwell, and a rotation circuit also is designed by the authors in the end of the paper.     

Development of a Novel Optimal Backstepping Control Algorithm of Magnetic Impeller-Bearing System for Artificial Heart Ventricle Pump

Abstract

In this work, a new backstepping control algorithm is developed for accurate suspension of the rotating impeller in the artificial heart based on supported magnetic suspension system. The magnet suspension system of the artificial heart ventricle consists mainly of the proposed controller and magnetic coils. The controller is used to actuate the magnetic coils with required currents to establish the magnetic field necessary for suspending the impeller at accurate position. Two pairs of magnetic coils at each end of the rotor are responsible for suspension in both vertical and horizontal planes such as three-dimension suspension control is achieved. The backstepping control algorithm is developed using the stability analysis based on the Lyapunov theory. The design parameters of backstepping controller have direct impact on the performance of controlled system. The present work suggested Particle Swarm Optimization technique for tuning these design parameters toward better performance of proposed controller. The effectiveness of the optimized backstepping controller is verified via computer simulation within MATLAB/SIMULINK environment.     

Directional control–response compatibility of joystick steered shuttle cars

Shuttle cars are an unusual class of vehicle operated in underground coal mines, sometimes in close proximity to pedestrians and steering errors may have very serious consequences. A directional control–response incompatibility has previously been described in shuttle cars which are controlled using a steering wheel oriented perpendicular to the direction of travel. Some other shuttle car operators are seated perpendicular to the direction of travel and steer the car via a seat mounted joystick. A virtual simulation was utilised to determine whether the steering arrangement in these vehicles maintains directional control–response compatibility. Twenty-four participants were randomly assigned to either a condition corresponding to this design (consistent direction), or a condition in which the directional steering response was reversed while driving in-bye (visual field compatible). Significantly less accurate steering performance was exhibited by the consistent direction group during the in-bye trials only. Shuttle cars which provide the joystick steering mechanism described here require operators to accommodate alternating compatible and incompatible directional control–response relationships with each change of car direction.

Practitioner Summary: A virtual simulation of an underground coal shuttle car demonstrates that the design incorporates a directional control–response incompatibility when driving the vehicle in one direction. This design increases the probability of operator error, with potential adverse safety and productivity consequences.     

Quantum steering and entanglement in three-mode triangle Bose–Hubbard system

We consider the possibility of generation steerable states in Bose–Hubbard system composed of three interacting wells in the form of a triangle. We show that although our system still fulfills the monogamy relations, the presence of additional coupling which transforms a chain of wells onto triangle gives a variety of new possibilities for the generation of steerable quantum states. Deriving analytical formulas for the parameters describing steering and bipartite entanglement, we show that interplay between two couplings influences quantum correlations of various types. We compare the time evolution of steering parameters to those describing bipartite entanglement and find the relations between the appearance of maximal entanglement and disappearance of steering effect.     

Adaptive steering‐based HDTC algorithm for PMSM

This paper introduces sensorless hysteresis direct torque control for permanent magnet synchronous motors to provide a reduced torque pulsation profile, which leads to a smaller mechanical vibration. The suggested algorithm utilizes the principle of vehicle steering, which continuously fixes the direction of the vehicle in the track. Moreover, the algorithm efficiently employs the output of torque and the output of flux error controllers used in basic hysteresis direct torque control to select two nonzero adjacent vectors. The initial switching time for the selected vectors is determined by a function that considers the absolute magnitude of the torque error and the magnitude of the flux error in addition to the space angle position of the stator flux. To reduce the processing time in the control signal flow, a suggested structure for switching the initial time of the selected vectors is developed. The final switching time of the vectors is adaptively adjusted according to the minimum required stator voltage to drive the load and according to the stored rotor energy that arises due to the inertia of the mechanical load connected to the motor shaft. The simulation results along with the experimental results show a fast dynamic response of torque, relatively reduced torque ripples, and reduced current harmonics compared to the basic hysteresis direct torque control.     

Quantum steering borders in three-qubit systems

We discuss a family of states describing three-qubit systems in a context of quantum steering phenomena. We show that symmetric steering cannot appear between two qubits—only asymmetric steering can appear in such systems. The main aim of this paper is to discuss the possible relations between the entanglement measures and steering parameter for two-mode mixed state corresponding to the qubit–qubit subsystem. We have derived the conditions determining boundary values of the negativity parametrized by concurrence. We show that two-qubit mixed state cannot be steerable when the negativity of such state is smaller than, or equal to, its boundary value. Finally, we have found ranges of the values of the mixedness measure, parametrized by concurrence and negativity for steerable and unsteerable two-qubit mixed states.     

基于力矩信息的拖拉机转向动态PID控制方法

针对拖拉机驾驶机器人自主转向系统在转向过程中的阻尼具有非线性和时变性的特点,同时为了提高转向系统的控制性能,设计了基于力矩信号检测的拖拉机转向控制系统,其由力矩传感器、STM32处理器、工控机、驱动器及直流电机等组成.首先通过仿真研究不同力矩时的最优PID控制参数,给出不同力矩时的最优PID参数规律,再通过力矩传感器检测的力矩信号动态调整PID参数来控制电机的转向.仿真及实验结果均表明,基于力矩信号反馈的拖拉机动态PID转向控制方法能够有效控制拖拉机的方向,响应快、超调小、适应性强.     

一种改进的可变对角加载自适应波束形成算法

由于观测方向误差的存在,使得实际获得的方向向量与其理论值产生偏差,进而对各类自适应波束形成算法性能造成较大影响。为此提出一种有效的对角加载自适应波束形成算法,首先利用目标信号的方向向量在噪声子空间中投影最小的原理,对带有误差的方向向量进行校正,然后再使用可变对角加载原理求得对角加载因子,对实际获得的自相关矩阵进行对角加载后,形成自适应波束,从而很好地消除了方向向量误差造成的影响。算法能够有效克服目标信号对消现象,并具有良好的保形能力和快速收敛的特点。计算机仿真结果验证了这些优点。