Compact Control System Research Articles

Theoretical and experimental investigations on thermal management of a PEMFC stack

In recent years micro-cogeneration systems (μ-CHPs), based on fuel cells technology, have received increasing attention because, by providing both useful electricity and heat with high efficiency, even at partial loads, they can have a strategic role in reduction of greenhouse gas emissions. For residential applications, the proton exchange membrane fuel cell (PEMFC), is considered the most promising, since it offers many advantages such as high power density, low operating temperature, and fast start-up and shutdown. In this paper the electrical and thermal behaviors of a PEMFC stack, suitable for μ-CHP applications, have been investigated through experimental and numerical activity. The experimental activity has been carried out in a test station in which several measurement instruments and controlling devices are installed to define the behavior of a water-cooled PEMFC stack. The test station is equipped by a National Instruments Compact DAQ real-time data acquisition and control system running Labview™ software. The numerical activity has been conducted by using a model, properly developed by the authors, based on both electrochemical and thermal analysis. The experimental data have been used to validate the numerical model, which can support and address the experimental activity and can allow to forecast the behavior and the performance of the stack when it is a component in a more complex energy conversion system.

A long-term in situ calibration system for chemistry analysis of seawater

An in situ calibration system is a versatile exploration instrument for electrochemical sensors investigating the biochemical properties of the marine environment. The purpose of this paper is to describe the design of an auto-calibrating system for electrochemical (pH) sensors, which permits two-point in situ calibration, suitable for long-term measurement in deep sea aqueous environments. Holding multiple sensors, the instrument is designed to perform long-term measurements and in situ calibrations at abyssal depth (up to 4000 m). The instrument is composed of a compact fluid control system which is pressure-equilibrated and designed for deep-sea operation. In situ calibration capability plays a key role in the quality and reproducibility of the data. This paper focuses on methods for extending the lifetime of the instrument, considering the fluidics design, mechanical design, and low-power consumption of the electronics controller. The instrument can last 46 d under normal operating conditions, fulfilling the need for long-term operation. Data concerning pH measured during the KNOX18RR cruise (Mid-Atlantic Ridge, July-August, 2008) illustrate the desirable properties of the instrument. Combined with different electrodes (pH, H2, H2S, etc.), it should be of great utility for the study of deep ocean environments, including water column and diffuse-flow hydrothermal fluids.

Optical force measurement system with mirror probe for nanoprobing inside a scanning electron microscope

In nanoprobing measurements the quality of the electrical contact strongly depends on the contact force. Probing semiconductors such as silicon requires applying very high and stable forces to establish an ohmic contact between the probe tip and the structure under study. Therefore, a compact force control system is needed for nanoprobing measurements inside a high-resolution scanning electron microscopy (SEM) system. In this work we have developed an optical force measurement system (OFMS) for nanoprobing based on the reflection of a laser beam from a mirror of the probe towards a position-sensitive photodiode detector (PSD). The system principle is similar to the so-called optical-lever principle used in atomic force microscopy (AFM). However, geometrical restrictions of the SEM chamber and adjacent probes require the incident and reflected laser beams to be on the same plane as the probe cantilever. This is achieved by placing a small mirror element perpendicular onto the cantilever surface. The use of high-precision nanomanipulators with OFMS allows to position probe tips on a selected structure on a macroscopic-scale sample with nanometer precision. The slim design of the nanomanipulator and the OFMS system allows to place several force controlled tips on the same nanostructure.

Application of quantum cascade lasers and infrared-fibres for the monitoring and control of industrial plasma processes

Quantum cascade lasers (QCL) offer attractive options for the application of mid-infrared absorption spectroscopy for industrial process monitoring and control. In particular the in-situ measurement of reactive plasma compounds can give new insight into the reaction kinetics of industrial plasma processes. For these purposes the compact quantum cascade laser measurement and control system (Q-MACS) has been combined with an infrared-fibre to allow a flexible and completely dust-sealed incoupling of the infrared radiation into the reactor chamber of an industrial plasma surface modification system. The system has been completed with a fast and compact detector and a data acquisition system to monitor concentrations of species of interest in the plasma process online. First tests proofed the potential of this approach.

Pneumatic balloon actuators for tactile feedback in robotic surgery

PurposeRobotic surgery is limited by the lack of haptic feedback to the surgeon. The addition of tactile information may enable surgeons to feel tissue characteristics, appropriately tension sutures, and identify pathologic conditions. Tactile feedback may also enable expansion of minimally invasive surgery to other surgical procedures and decrease the learning curve associated with robotic surgery. This paper aims to explore a system to provide tactile feedback.Design/methodology/approachA pneumatic balloon‐based system has been developed to provide tactile feedback to the fingers of the surgeon during robotic surgery. The system features a polydimethyl siloxane actuator with a thin‐film silicone balloon membrane and a compact pneumatic control system. The 1.0 × 1.8 × 0.4 cm actuators designed for the da Vinci system feature a 3 × 2 array of 3 mm inflatable balloons.FindingsThe low‐profile pneumatic system and actuator have been mounted directly onto the da Vinci surgical system. Human perceptual tests have indicated that pneumatic balloon‐based tactile input is an effective means to provide tactile information to the fingers of the surgeon.Research limitations/implicationsApplication of a complete tactile feedback system is limited by current force sensing technologies.Originality/valueThe actuators have been designed such that they can be mounted directly onto the hand controls of the da Vinci robotic system, and are scalable such that they can be applied to various robotic applications.

A compact active control system for tonal noise reduction in axial fans

A compact active control system for tonal noise reduction in axial fans

A Compact Guidance, Navigation, and Control System for Unmanned Aerial Vehicles

The Flight Control System 20 (FCS20) is a compact, self-contained Guidance, Navigation, and Control system that has recently been developed to enable advanced autonomous behavior in a wide range of Unmanned Aerial Vehicles (UAVs). The FCS20 uses a floating point Digital Signal Processor (DSP) for high level serial processing, a Field Programmable Gate Array (FPGA) for low level parallel processing, and GPS and Micro Electro Mechanical Systems (MEMS) sensors. In addition to guidance, navigation, and control functions, the FCS20 is capable of supporting advanced algorithms such as automated reasoning, artificial vision, and multi-vehicle interaction. The unique contribution of this paper is that it gives a complete overview of the FCS20 GN&C system, including computing, communications, and information aspects. Computing aspects of the FCS20 include details about the design process, hardware components, and board configurations, and specifications. Communications aspects of the FCS20 include descriptions of internal and external dataflow.The information section describes the FCS20 Operating System (OS), the Support Vehicle Interface Library (SVIL) software, the navigation Extended Kalman Filter, and the neural network based adaptive controller. Finally, simulation-based results as well as actual flight test results that demonstrate the operation of the guidance, navigation, and control algorithms on a real Unmanned Aerial Vehicle (UAV) are presented.

A Low Force Valve for Dynamic Control of Molten Plastics in a Mold

Abstract Polymer processing has been limited by the lack of direct flow and pressure control of the polymer melt at multiple points in space and time. Improved axial and radial valve designs are discussed that require negligible actuation force to control the flow of the pressurized melt. The forces resulting from pressure loads and shear stresses are first analyzed for an axial valve pin. Subsequently, a radial valve design is implemented and experimentally characterized using neat polycarbonate. A sigmoidal response surface is fit to the experimental data and found to very well model the observed pressure drop as a function of flow rate and valve pin position. The juncture loss at the valve port is then characterized by estimating and removing the pressure drops in the circular flow segments of the valve. Analysis indicated that the juncture loss is inversely proportional to the exposed area, or vesica piscis, formed between the circular flow channel in the valve body and the flow port on the moving valve pin. While applicable to many different polymer processing operations, the validated models are used to show the dynamic valve pin position as a function of the desired flow rate and desired cavity pressure in the hot runner of an injection mold. Finally, the impact of the designs on lower power, more compact mechanical and control system designs are discussed.

Research on embedded MAS based manipulator control

PurposePresents an embedded MAS (Multi‐Agent System) based control method for multi link series manipulators.Design/methodology/approachThe manipulator's completing operation work is based on several agents' cooperation. The entire embedded MAS of a manipulator is implemented in one ARM7 microprocessor. The multi agents and the communications between the agents are constructed depending on the real‐time multitasking capability and the system services of real time operation system, μC/OS‐(tm). An improved distributed inverse kinematics algorithm, which is the foundation the agents' behavior strategies, and the system architecture designing are described in detail.FindingsThis method is very suitable for tele‐operation redundant manipulators' embedded control systems designing, with high reliability.Research limitations/implicationsUsing this paradigm, the embedded system firmware development for a redundant manipulator would be very easy and the code would be reusable. A few amendments should be made for miscellaneous manipulators.Practical implicationsIt is suitable for controlling a high reliability expected tele‐operation manipulator system.Originality/valueThe embedded MAS based manipulator control paradigm has several attractive advantages, led from MAS theory. Basing this method, we do not require computing the traditional inverse (or pseudoinverse) Jacobian matrix to control a redundant manipulator, especially for mobile redundant robot based on a compact embedded control system, expecting high reliability and potential complexity for coping with dynamical environments. The development procedure would be very easy and the code would be reusable. A few amendments should be made for different manipulators.

Adaptive active control of flexural waves in a beam in the presence of a nearfield

This paper describes a wave-based, adaptive, feedforward system for the control of flexural waves in a beam when a significant nearfield wave is present. Many potential applications for active vibration control require a physically compact control system, in which the error sensors are located close to the control actuator. Because of the small physical size of the control system, there can be a significant nearfield wave as well as propagating waves in the vicinity of the error sensors, and the presence of this nearfield must be taken into account. An estimate of the downstream propagating wave amplitude is obtained by digitally filtering and combining the outputs of an array of three sensors, and is used as a cost function in a conventional filtered X-LMS adaptive algorithm. This has significant advantages over the more conventional approach in which the response at a single point is used as a cost function. Numerical simulations and experimental implementation of the control achieved with the wave-based and conventional systems are presented. It is seen that the wave-based system can offer significantly better broadband attenuation than the conventional approach in which response at a point is minimised.

Experiment of Antenna Pointing Control for Satellite Communications Tracking Systems on Vehicles. Experiment of Acquisition and Tracking for BS Satellite.

Satellite communications are utilized widely fields -navigations, broadcast and scientific. Recently mobile communications and satellite broadcast are developing remarkably. And the active antenna pointing sysem is required so that we may communicate with satellite in transportation, such as sail boat, truck and car. In this case, we can assume that the antenna base receives perturbation of a high frequency, and we must construct a compact antenna control system with high response. In this research, we use an existing antenna system consisting of a 2-axis gimbal structure driven by stepping motor and a 3-axis vibratory rate gyroscope to control the base attitude. The antenna system is used to track a Japanese broadcast satellite in geostationary orbit. We propose intellectual satellite position search system with feedback control using AGC level and feedforward control using gyro sensor to correct various errors. This papers discusses the 2-axis gimbal structure, sensor system, control algorithm, and experimental result.

A method to calculate the acoustic response of a thin, baffled, simply supported poroelastic plate

The Helmholtz integral equation formulation is used to produce the solution for the acoustic field reflected from a finite, thin, poroelastic plate in a rigid baffle with simply supported edges. The acoustic properties of the porous material are predicted using the effective fluid assumption. The solutions for the displacement of the plate and for the loading acoustic pressures are given in the form of the sine transform. The sine transform coefficients are obtained from the solution of a system of linear equations resulting from three integral Helmholtz formulations which relate the displacement of the plate and the acoustic pressures on the front and on the back of the plate. The effect of an air gap behind the plate in the front of a rigid wall is also considered. A parametric study is performed to predict the effect of variations in the parameters of the poroelastic plate. It is shown that thin, light, poroelastic plates can provide high values of the acoustic absorption even for low frequency sound. This effect can be exploited to design compact noise control systems with improved acoustic performance.

Compact disc players in the laboratory: experiments in optical storage, error correction, and optical fiber communication

The compact disc player is a synergy of optics, communication theory, digital signal processing, and control engineering. This familiar consumer product may be employed as a cost-effective laboratory instrument to teach the fundamentals of optical storage, error detection and correction, and optical communication. The compact disc audio system, from analog input, through optical storage and distribution, to audio reproduction, provides an excellent model of a complete real-world optical transmission and storage system. A series of experiments, which illustrate some of the more significant operational principles of the compact disc player, are presented in this contribution. Optical read-out and the physics of information density are explored through a set of experiments in optical storage. Error detection and correction are studied experimentally by evaluating the performance of the compact disc player's error control system. The design of an optical fiber communication system is studied by extracting the channel bit stream from a compact disc player, transmitting it over an optical fiber link, and then reinserting it back into the compact disc player for audio reproduction.

Recipe Control for Closed-Field Unbalanced Magnetron Sputter Ion-Plating Machines

The requirements, specification and chosen implementation of a secure, reliable and compact process control system on a personal computer is described for automating closed-field unbalanced magnetron sputter ion-plating machines. The made-to-order nature of many such installations has consequences for the design of the control system, necessitating great flexibility and ease of reconfiguration. The system described has been implemented for the deposition of Al2O3, alloy nitride, ‘diamond-like’ carbon and other coatings. Examples are presented of the control script language and a typical mimic display.

Integrating fuzzy control of the dexterous National Taiwan University (NTU) hand

Compared to traditional tendon-driven robots, the mechanism design of the National Taiwan University hand has an uncoupled configuration and is compact in size. In this paper, a specially designed compact control system, which is embedded into the NTU hand to satisfy the limited space, is developed to perform the control of the five-finger robot with 17 degrees of freedom (DOF). There are total 17 actuators including transmission mechanism, 17 potentiometers, and 18 tactile sensor pads to be integrated. Those 17 actuators should be controlled simultaneously by integrating 17 position sensing signals and 18 tactile signals. Multi-loop position control is further complicated by multi-loop force control as well as sensor integration. The proposed control system distributes the computation load into several modules and utilizes the DSP chip. It takes advantage of the fuzzy control by introducing the knowledge of human and sensor fusion with the finger joint and tactility. Using the communication function of the control system, the knowledge bases can be loaded for high level computation and modified during run time.

Compact data processing and control system for SIMS and AES

An improved version of a data processing and control system has been used with state-of-the-art AES and SIMS instruments. It consists of a mainframe with CPU, buffer and IEEE 488 interface to a host computer and a range of plug-in submodules. Its features include three-dimensional analysis, imaging, multichannel spectra and sample bias control. The performance of the system has been tested by AES and SIMS depth profile measurements of Si-Ge multilayers.

A Combustion Air Changeover Control for Heat Recovery Boilers

This paper presents an automatic combustion air changeover control for the heat recovery boilers of a co-generation plant. The boiler, with a burner system, operates either on exhaust gas of a gas turbine generator (GTG) or on a forced draft fan (FDF). The changeover control enables continuous boiler operation even in case of GTG emergency shutdown. A compact control system provides automatic air changeover.

A compact scanning tunneling microscopy control and data acquisition system based on a Macintosh II workstation

A compact system based on a Macintosh II workstation for scanning tunneling microscopy (STM) control, data acquisition, and image display and processing is presented. To access the versatile analog electronics and the piezo scanner of our STM, a multifunction board (MacAdios II) is employed as an interface. The on-board timer/counter permits well defined time intervals between each tip movement and subsequent data acquisition. For on-line control and image display of scanning processes an efficient code was written in Pascal and C. To achieve simple and user-friendly operation, the program takes advantage of so-called mouse–window–desktop techniques supported by the Macintosh operating system. The entire code has a modular structure and therefore facilitates easy replacement of existing modules or implementation of additional ones.

Low Cost Digital Controller for PWM Converter

The design of a compact control system for a sinusoidal PWM transistor inverter is presented. The hardware of the control system consists of 16-bit microcontroller with a few additional components. The PWM signales are generated in a digital way. In addition to generation of the PWM signals, the microcontroller performs closed loop control functions. Both sampling frequency and PWM carrier frequency can be adjusted by software, according to the requirments from the digital controller and the power transistors used in converter. The sampling frequency is up to several KHz, and the carrier frequency from less than 1 KHz to 46 KHz. Interaction with an operator or an on-line supervisory computer is provided through a serial communication, digital port or analog input lines. Simulation and experimental test results from an implementation of the control system on a high power IGBT inverter are given.