82,822 research outputs found
Closed-loop autonomous docking system
An autonomous docking system is provided which produces commands for the steering and propulsion system of a chase vehicle used in the docking of that chase vehicle with a target vehicle. The docking system comprises a passive optical target affixed to the target vehicle and comprising three reflective areas including a central area mounted on a short post, and tracking sensor and process controller apparatus carried by the chase vehicle. The latter apparatus comprises a laser diode array for illuminating the target so as to cause light to be reflected from the reflective areas of the target; a sensor for detecting the light reflected from the target and for producing an electrical output signal in accordance with an image of the reflected light; a signal processor for processing the electrical output signal in accordance with an image of the reflected light; a signal processor for processing the electrical output signal and for producing, based thereon, output signals relating to the relative range, roll, pitch, yaw, azimuth, and elevation of the chase and target vehicles; and a docking process controller, responsive to the output signals produced by the signal processor, for producing command signals for controlling the steering and propulsion system of the chase vehicle
Intelligent Traffic Signal Control System Using Embedded System
A development of an intelligent traffic signal control (ITSC) system needed because present traffic light controllers are based on old microcontroller such as AT89C51 which has very less internal memory and no in-built ADC. These systems have limitation because they will use the predefined program that does not have the flexibility of modification on real time application. The present traffic system have fixed time interval for green and red signal which does not provide the flexibility to the system. The ITSC system consist of high-performance, low power AVR_32 microcontroller with 32kbytes of in-system programmable flash memory and in-built 8-channel, 10-bit ADC which is required to process the IR input from sensor network. The ITSC system will able to deal two basic problem of traditional traffic light system: i) Detection of traffic volume by using genetic algorithm. ii) Emergence vehicle detection such as ambulance, police etc by using wireless sensor network (IR) embedded at the signal intersection. Keywords: Traffic Volume Estimation, Genetic Algorithm, wireless sensor network, Vehicle detection, Intelligent Traffic Signal Controller, embedded system
Effect of Emergency Interrupt Complexity on the Performance of Adaptive Network Based Fuzzy Inference Traffic Light Control System
ANFIS controller is an advance technique of controlling in Traffic Light Control System (TLCS) which adjusts signal timing parameters in response to real time traffic flow fluctuations. However, the performance of ANFIS controller has not been investigated in an emergency environment. Hence, this paper investigates the effect of emergency lane sensor signal interrupt complexity on the performance of an Adaptive Network Based Fuzzy Inference System (ANFIS) TLCS. The cross roads junction with two lanes per road was considered. One Pedestrian and one Railway lane were considered as emergency lanes. One Traffic Light (TL) was used to control vehicle on each road. ANFIS-TLCS was simulated using graphic user interface tool of the MATLAB. The GUI was simulated for the four different cases of emergency interrupt complexity at some specific simulation periods and the preset number of vehicles for each lane using slide button. Performance of the ANFIS controller was tested for: no, more and most complexity emergency Interrupt cases using Cost Efficiency (CE) as a performance metric. The results obtained showed that ANFIS controller performed differently in all tested cases and worse as the complexity increases but performed relatively equal and better at a higher simulation period regardless of the interrupt complexity. Hence, ANFIS controller is recommended as a better Traffic Light controlling technique regardless of any complexity at the road junction. Keywords: Cross road, Traffic Light, Emergency Interrupt Complexity, ANFIS Object, and Cost Efficienc
A Visual Formalism for Interacting Systems
Interacting systems are increasingly common. Many examples pervade our
everyday lives: automobiles, aircraft, defense systems, telephone switching
systems, financial systems, national governments, and so on. Closer to computer
science, embedded systems and Systems of Systems are further examples of
interacting systems. Common to all of these is that some "whole" is made up of
constituent parts, and these parts interact with each other. By design, these
interactions are intentional, but it is the unintended interactions that are
problematic. The Systems of Systems literature uses the terms "constituent
systems" and "constituents" to refer to systems that interact with each other.
That practice is followed here. This paper presents a visual formalism, Swim
Lane Event-Driven Petri Nets, that is proposed as a basis for Model-Based
Testing (MBT) of interacting systems. In the absence of available tools, this
model can only support the offline form of Model-Based Testing.Comment: In Proceedings MBT 2015, arXiv:1504.0192
Time Domain Simulations of Arm Locking in LISA
Arm locking is a technique that has been proposed for reducing laser
frequency fluctuations in the Laser Interferometer Space Antenna (LISA), a
gravitational-wave observatory sensitive in the milliHertz frequency band. Arm
locking takes advantage of the geometric stability of the triangular
constellation of three spacecraft that comprise LISA to provide a frequency
reference with a stability in the LISA measurement band that exceeds that
available from a standard reference such as an optical cavity or molecular
absorption line. We have implemented a time-domain simulation of arm locking
including the expected limiting noise sources (shot noise, clock noise,
spacecraft jitter noise, and residual laser frequency noise). The effect of
imperfect a priori knowledge of the LISA heterodyne frequencies and the
associated 'pulling' of an arm locked laser is included. We find that our
implementation meets requirements both on the noise and dynamic range of the
laser frequency.Comment: Revised to address reviewer comments. Accepted by Phys. Rev.
Thumb-actuated two-axis controller
A two axis joystick controller is described. It produces at least one output signal in relation to pivotal displacement of a member with respect to an intersection of the two axes. The member is pivotally movable on a support with respect to the two axes. The support has a centrally disposed aperture. A light source is mounted on the pivotally movable member above the aperture to direct light through the aperture. A light sensor is mounted below the aperture in the support at the intersection of the two axes to receive the light from the light source directed through the aperture. The light sensor produces at least one output signal related to a location on the sensor at which the light from the light source strikes the sensor
Understanding and Design of an Arduino-based PID Controller
This thesis presents research and design of a Proportional, Integral, and Derivative (PID) controller that uses a microcontroller (Arduino) platform. The research part discusses the structure of a PID algorithm with some motivating work already performed with the Arduino-based PID controller from various fields. An inexpensive Arduino-based PID controller designed in the laboratory to control the temperature, consists of hardware parts: Arduino UNO, thermoelectric cooler, and electronic components while the software portion includes C/C++ programming. The PID parameters for a particular controller are found manually. The role of different PID parameters is discussed with the subsequent comparison between different modes of PID controllers. The designed system can effectively measure the temperature with an error of ± 0.6℃ while a stable temperature control with only slight deviation from the desired value (setpoint) is achieved. The designed system and concepts learned from the control system serve in pursuing inexpensive and precise ways to control physical parameters within a desired range in our laboratory
The performance of arm locking in LISA
For the laser interferometer space antenna (LISA) to reach it's design
sensitivity, the coupling of the free running laser frequency noise to the
signal readout must be reduced by more than 14 orders of magnitude. One
technique employed to reduce the laser frequency noise will be arm locking,
where the laser frequency is locked to the LISA arm length. This paper details
an implementation of arm locking, studies orbital effects, the impact of errors
in the Doppler knowledge, and noise limits. The noise performance of arm
locking is calculated with the inclusion of the dominant expected noise
sources: ultra stable oscillator (clock) noise, spacecraft motion, and shot
noise. Studying these issues reveals that although dual arm locking [A. Sutton
& D. A Shaddock, Phys. Rev. D 78, 082001 (2008).] has advantages over single
(or common) arm locking in terms of allowing high gain, it has disadvantages in
both laser frequency pulling and noise performance. We address this by
proposing a hybrid sensor, retaining the benefits of common and dual arm
locking sensors. We present a detailed design of an arm locking controller and
perform an analysis of the expected performance when used with and without
laser pre-stabilization. We observe that the sensor phase changes beneficially
near unity-gain frequencies of the arm-locking controller, allowing a factor of
10 more gain than previously believed, without degrading stability. We show
that the LISA frequency noise goal can be realized with arm locking and
Time-Delay Interferometry only, without any form of pre-stabilization.Comment: 28 pages, 36 figure
A digital signal processor based optical position sensor and its application to flexible beam control
A Digital Signal Processor (DSP) based optical position sensor was developed. The sensor system consists of the following components: 1) analog electronics, 2) the DSP based synchronous demodulation software, 3) PC based interface software which samples and saves the data, and 4) PC based control codes for a flexible beam. experiment.
The ability of the system to determine the distance from the optical sensor to the power modulated light source was assessed by the following tests: 1) a stationary drift test to evaluate the system\u27s noise, 2) a short-range test to determine the resolution of the optical sensor over a 25mm range and, 3) a long-range test to evaluate the ability of the system to predict the location of the optical sensor over a 600mm range. It was found that the resolution of the system is approximately 0.5mm for the short range test and 5mm for the long range test.
Finally, the sensor was deployed for the position feedback of a flexible beam experiment. Performance indices used to evaluate the response of the system were: 1) the sum of the squared position error, 2) the final steady state position error of the end of the flexible beam, and 3) the 5% settling time of the flexible beam. A number of control laws were evaluated and it was determined that a variable PID controller produced the best overall performance. The system can consistently position the end of the flexible beam from a +1-20cm to within 5mm of the command position in approximately 8 seconds with a properly tuned controller
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