Terminal Control System Research Articles

Development of a Terminal Control System with Variable Minimum Airflow Rate

A constant minimum airflow rate is used in conventional Single Duct Variable Air Volume Terminal Box control sequences. This control sequence can cause occupant discomfort or use excessive energy under partial load conditions. If the minimum airflow rate is higher than required; terminal boxes will have significantly more simultaneous heating and cooling; and AHUs will consume more fan power. Buildings will have indoor air quality problems if the minimum airflow rate is less than required. Many engineers and researchers have investigated advanced variable air volume terminal box control algorithms without a system retrofit for thermal comfort; indoor air quality and energy savings. In this study a developed control system with variable minimum airflow rate for Single Duct Variable Air Volume Terminal Boxes was applied and validated using an actual building and evaluated for comfort; indoor air quality and energy consumption. The energy consumption and thermal performance of terminal boxes using the conventional and proposed control algorithms were compared.

Robust Nonsingular Terminal Sliding-Mode Control for Nonlinear Magnetic Bearing System

This study presents a robust nonsingular terminal sliding-mode control (RNTSMC) system to achieve finite time tracking control (FTTC) for the rotor position in the axial direction of a nonlinear thrust active magnetic bearing (TAMB) system. Compared with conventional sliding-mode control (SMC) with linear sliding surface, terminal sliding-mode control (TSMC) with nonlinear terminal sliding surface provides faster, finite time convergence, and higher control precision. In this study, first, the operating principles and dynamic model of the TAMB system using a linearized electromagnetic force model are introduced. Then, the TSMC system is designed for the TAMB to achieve FTTC. Moreover, in order to overcome the singularity problem of the TSMC, a nonsingular terminal sliding-mode control (NTSMC) system is proposed. Furthermore, since the control characteristics of the TAMB are highly nonlinear and time-varying, the RNTSMC system with a recurrent Hermite neural network (RHNN) uncertainty estimator is proposed to improve the control performance and increase the robustness of the TAMB control system. Using the proposed RNTSMC system, the bound of the lumped uncertainty of the TAMB is not required to be known in advance. Finally, some experimental results for the tracking of various reference trajectories demonstrate the validity of the proposed RNTSMC for practical TAMB applications.

Inventory-based dispatching of automated guided vehicles on container terminals

This paper deals with automated guided vehicles (AGVs) which transport containers between the quay and the stack on automated container terminals. The focus is on the assignment of transportation jobs to AGVs within a terminal control system operating in real time. First, we describe a rather common problem formulation based on due times for the jobs and solve this problem both with a greedy priority rule based heuristic and with an exact algorithm. Subsequently, we present an alternative formulation of the assignment problem, which does not include due times. This formulation is based on a rough analogy to inventory management and is solved using an exact algorithm. The idea behind this alternative formulation is to avoid estimates of driving times, completion times, due times, and tardiness because such estimates are often highly unreliable in practice and do not allow for accurate planning. By means of simulation, we then analyze the different approaches. We show that the inventory-based model leads to better productivity on the terminal than the due-time-based formulation.

加減速環境下における超音速軸対称型インテークの制御に関する実験的研究｀＊１´

A control system of variable geometry mixed compression axisymmetric intake is experimentally studied at ONERA S3 supersonic wind tunnel. The acceleration/deceleration of the space plane is simulated by changing the free stream velocity. The intake is successfully controlled with 90% of the maximum total pressure recovery and mass capture ratio. In this experiment, two subjects about control of axisymmetric intake are also cleared. First, the effect of the trapping of the terminal shock by bleed holes causes the disturbances in the terminal shock control system. Second, a special compression form change operation is necessary when the intake compression form change from all external compression to mixed compression.

Simple neuro-controller with a modified error function for a synchronous generator

A simple neuro-controller for a synchronous generator is presented in this paper. The controller consists of a single neuron trained on-line using the back propagation algorithm based on a modified error function. The modified error function uses the controlled variable and its derivatives. Based on the variables used in the modified error function, the controller performs the functions of terminal voltage control and power system stabilizer. Simulation studies for a single-machine and multi-machine power system environment are presented to demonstrate the effectiveness of using the simple neuro-controller.

Human Factors Lessons Learned in Terminal Air Traffic Control System Procurement

The Federal Aviation Administration Standard Terminal Automation Replacement System (STARS) acquisition program will replace aging terminal radar workstations and computers at 172 US airports. In 1997, human factors issues associated with this commercial off-the-shelf product emerged that spanned STARS tower, terminal, and maintenance components. Many lessons were learned from subsequent intensive human factors efforts to incorporate user requirements into the STARS equipment. This experience resulted from diverse usability assessments and controlled tests as well as the application of rapid prototyping tools. Design changes were defined and prototyped under significant time pressure using an integrated team approach. Due to the breadth and the size of the program, the lessons learned will extend to air traffic control and other system acquisitions and will be of interest to practitioners in terms of specific techniques and issues.

Synthesis of a Terminal Control System in an Orthogonal-Function Basis

Synthesis of a Terminal Control System in an Orthogonal-Function Basis

On the location of filtering in a linear terminal control system

This paper deals with a linear system with terminal control which has application to the homing guidance loop. The characteristic considered here is the effect of filtering on the error position measurement when the filter is located before the time varying gain. It is shown that such filtering profoundly modifies the behavior of the loop with possible desta-bilization of the adjoint system.

Algorithmic Methods of Increasing Reliability of Space Vehicles Terminal Control

Certain ways to increase reliability of space vehicles control via design of the appropriate control algorithms are discussed. Such algorithms provide control capable of fulfilling the terminal task in spite of failures of system parts. Implementation of the techniques is exemplified by terminal rendez-vous control system.

Control aspects of efficient rocket propulsion systems

The means for enhancing the efficiency of rocket propulsion of spacecraft is considered in terms of the control of propellant consumption, trajectory planning, and in-flight operations management. Particular attention is given to techniques by which all the fuel and oxidizer are consumed completely by mixture adjustment as an example of a terminal control system providing significant propulsion efficiency.

Interferometer Design for Elevation Angle Estimation

Radars that are developed for the purpose of monitoring aircraft landings in the terminal air traffic control system can be designed to exploit the relatively high signal-to-noise ratio that characterizes the power budgets calculated for such a link. An interferometer using a pair of low gain antennas can be used to obtain passive coverage over a targe azimuth and elevation sector. A large baseline can be used to obtain the desired elevation angle estimation accuracy. In this paper an optimal tradeoff between the width of the subarray aperture and the width of the interferometer baseline is performed that achieves a specified elevation angle estimation error while minimizing the overall height of the interferometer configuration. The algorithm searches through the class of antenna patterns that can be synthesized from so-called finite impulse response, linear phase digital filters. For the specific problem of designing an elevation sensor for monitoring landing aircraft on final approach, the elevation angle can be estimated with no more than 1-mrad rms error when the aircraft is within ± 60° azimuth, 2.5° to 40° elevation, using two 7-wavelength subarray antennas spaced 8 wave-lengths apart. The design of a separate sensor for resolving the interferometer ambiguities is formulated as a hypothesis testing problem and solved using statistical decision theory. A bound on the probability of an ambiguity error is derived that accounts for the effects of ground reflection multipath and receiver noise.

An Improved Control System for Van De Graaff Accelerators

In an effort to improve the energy stability and operating convenience of the Rutgers-Bell FN Tandem, a study has been made of the processes involved in the standard Van de Graaff corona stabilization system. In the light of these observations, a terminal voltage control system has been designed using error signals derived both from the slit system and the capacity pickoff plates. The system operates using either the standard slit system, or the machines' Generating Voltmeter as the terminal voltage reference, switching automatically to the G. V. system when beam is lost for any reason.

Analytical methods of research into terminal area air traffic operations

The application of mathematical models of various suboperations in the terminal area, and the use of fast time simulation on a digital computer to study the operation of a complete terminal area traffic control system, are briefly demonstrated. Mathematical models are used to analyze the capacity of race track holding patterns, the laddering operation, and the instrument landing system (ILS) funnel with time separations at the gate. The results of a fast time simulation on an IBM 7094, for an advanced method of providing sequencing and spacing for a single ILS runway are given. The landing system demonstrates a capacity of 32 landings/hr, along with runway availability for 20 takeoffs.

THE EFFECT OF RULE FLEXIBILITY ON SYSTEM ADAPTATION.

A study was performed to test the effect of strict vs. flexible operating rules on a simulated terminal air traffic control system under a variety of traffic conditions with constant load. Twelve college students were trained in control procedures, were assigned to two crews, and operated the system in a sequence of 24 problem sessions in which the variables were arranged in factorial combination. Only the change to more flexible rules produced consistently significant performance changes. The differences in the way the two crews responded to the changes in the rules depended on the degree of crew cohesiveness. A theoretical formulation of system adaptation derived from earlier studies with an air defense system is discussed, and a new formulation is presented which is consistent with the findings in both the present and the earlier studies.

Radar System Design for Spacecraft Terminal Control

This paper discusses several radar design considerations for use in the terminal control of manned and unmanned space vehicles of the maneuverable type. The main body of the paper deals with specific areas of radar development resulting from recent work in developing a terminal control system. The radar system discussed uses a transponder on board the vehicle. The transponder receives and transmits PCM commands and flight data in addition to reference pulses for angle and range tracking. The technical areas discussed are reliability of self-acquisition, pulse code modulated (PCM) data transmission, semidigital ranging, and the accuracy of computed radar data.

Terminal control system applications

This paper describes a synthesis procedure for terminal control systems. The synthesis procedure is illustrated by application to the design of an aircraft automatic landing system. A simplified model for the landing aircraft is chosen and justified. The prediction equations for this model are discussed. Using the prediction equations, a two-condition terminal controller, which controls the altitude and altitude rate at time of touchdown to the desired values, is developed. The terminal control landing system developed is simplified by combining feedback loops in a straightforward fashion to arrive at a practical mechanization. A stability analysis of the simplified terminal controller, considered as a servo with time variable gains and time constants, is presented. The results of extensive analog computer simulation and flight test of the terminal control landing system developed in this paper are reviewed. It is shown that the synthesis procedures developed in this paper result in a system which can be implemented by state-of-art hardware to land aircraft successfully.

Multicondition Terminal Control Systems for Aircraft

A method is presented for synthesizing a type of control system applicable to automatic landing of aircraft and designated as a multicondition terminal control system. This closed-loop control system is designed to cause the response of a controlled member to meet several independently specified conditions at a particular instant of time. The desired values of altitude and altitude rate at touchdown typify such conditions. Because the S3^stem operates to shape the response at one time only, it is suitable for use with controlled members that have oscillatory or divergent responses to forcing inputs.