Loop Control Algorithm Research Articles

Simulink Model of Parallel Resonant Inverter with DSP Based PLL Controller

Resonant converters can operate at high switching frequencies with low switching losses. However, in order to reduce switching losses resonant frequency has an important role in the design. In this study, a DSP based closed loop phase locked loop (PLL) control algorithm for parallel resonant inverter is designed and simulated with MATLAB/Simulink. The validity of the Simulink model of current source inverter is tested for different loads and gain values obtained from Jury’s stability. The developed DSP controlled parallel resonant inverter tracks the resonant frequency and achieves soft switching. DOI: http://dx.doi.org/10.5755/j01.eee.21.6.13751

Aircraft Anti-Skid Brake Control Based on High-Speed on-off Valve

Aircraft hydraulic brake system usually use pressure servo valve for anti-skid brake control. As pressure servo valve realizes the pressure closed loop by hydraulic feedback loop, this structure increased the complexity of the processing and manufacturing, restricted the pressure closed loop parameters adjustment, and increased the difficulty of debugging the system design. Pressure servo valve is expensive and difficult to process, poor ability to resist pollution. This paper proposed a slip ratio large closed loop aircraft anti-skid brake control method based on high-speed on-off valve, built the model of aircraft ground vertical taxiing and slip ratio large closed loop control algorithm in the MATLAB/SIMULINK, and built the model of aircraft hydraulic brake system based on on-off valve in the AMESim and a joint simulation was carried out. The simulation results show that the aircraft anti-skid brake control method based on high-speed on-off valve is feasible, and the on-off valve is cheap with strong ability to resist pollution, easy processing and manufacturing and so on, showing a good application prospect.

Design of the Vehicular Eletro-Optical Tracking Turntable Servo System and the Research on its Tracking Control Scheme

In order to realize the high precision tracking control of the vehicular eletro-optical tracking turntable with the car bodys vibration, it is necessary to design a high performance turntable servo system and a set of high precision eletro-optical tracking control scheme. In this paper, a digital servo system is designed, which has the control platform based on PC104 processor, has the torque motor as the actuator, has the gyro as the inertial velocity measurement tool and has the high precision encoder as the position measurement tool. Then, the gyrostabilized double speed loop control algorithm with disturbance observer compensating is designed to realize a good inertial velocity stability performace; and, a set of eletro-optical tracking compound position loop control scheme based on the target-missing quality data processing, the segmented PID control and the acceleration lag compensating control is proposed to enhance the eletro-optical tracking precision. The result shows that the tracking turntable based on the control technology designed in this paper is reliable, responses quickly, has a good speed stability performance and a high eletro-optical tracking precision performance.

Closed Loop Control Algorithm of Fuel Cell Output Power for a City Bus

Closed Loop Control Algorithm of Fuel Cell Output Power for a City Bus

Direct design of a velocity controller and load disturbance estimation for a self-balancing industrial manual manipulator

Self-balancing manual manipulators are devices that countervail the weight of a load that must be manually handled and moved by a human operator. Standard manipulators are made of a framework with an electric motor on the top and a spool connected to the motor shaft through a transmission gear. The load is hung by a handling device connected to a metallic rope wound on the spool. The device considered in this paper, in its current layout, is endowed with a load cell that measures the load weight and is controlled in an open loop. A new layout has been designed, which is not including the weighting load cell and is feedback controlled. The load’s counterbalance and movement are obtained by a velocity closed loop control algorithm designed using a direct design method, the Virtual Reference Feedback Tuning (VRFT). VRFT provides controller parameters tuning in a completely automatic way based on a single I/O batch measurement on the plant. Moreover, the elimination of the load weight transducer causes issues to some handling devices that need weight measurements to attach and detach the load. So, a load mass observer has been designed using a gravitational torque estimator, which is an enhanced version of standard disturbance torque observer for electric motors.

Evolution of the Space Shuttle Primary Avionics Software and Avionics for Shuttle Derived Launch Vehicles

As a result of recommendation from the Augustine Panel, the direction for Human Space Flight has been altered from the original plan referred to as Constellation. NASA s Human Exploration Framework Team (HEFT) proposes the use of a Shuttle Derived Heavy Lift Launch Vehicle (SDLV) and an Orion derived spacecraft (salvaged from Constellation) to a new flexible direction for space exploration. The SDLV must be developed within an environment of a constrained budget and a preferred fast development schedule. Thus, it has been proposed to utilize existing assets from the Shuttle Program to speed development at a lower cost. These existing assets should not only include structures such as external tanks or solid rockets, but also the Flight Software which has traditionally been a long pole in new development efforts. The and for the Space Shuttle was primarily developed in the 70 s and considered state of the art for that time. As one may argue that the existing and flight may be too outdated to the new SDLV effort, this is a fallacy if they can be evolved over time into a avionics platform. The technology may be outdated, but the concepts and flight algorithms are not. The reuse of existing and also allows for the reuse of development, verification, and operations facilities. The keyword is evolve in that these assets can the fast development of such a vehicle, but then be gradually evolved over time towards more modern platforms as budget and schedule permits. The gold of the flight is the control loop algorithms of the vehicle. This is the Guidance, Navigation, and Control (GNC) algorithms. This is typically the most expensive to develop, test, and verify. Thus, the approach is to preserve the flight software, while first evolving the supporting (such as Command and Data Handling, Caution and Warning, Telemetry, etc.). This can be accomplished by gradually removing the support software from the legacy flight leaving only the algorithms. The support software could be re-developed for modern platforms, while leaving the algorithms to execute on technology compatible with the legacy system. It is also possible to package the algorithms into an emulated version of the original computer (via Field Programmable Gate Arrays or FPGAs), thus becoming a GNC on a Chip solution where it could live forever to be embedded in modern platforms.

Experimental Research on Dynamic Voltage Sag Compensation Using 2G HTS SMES

A high temperature superconducting magnetic energy storage system (HT-SMES) is constructed using YBCO coated conductor and is integrated with a cryogenic system using sub-cooled LN2. A closed loop control algorithm, based on the digital signal processor (DSP) TMS320F2812, is proposed using the 2G HT-SMES to compensate dynamic voltage sag in power systems. A dynamic simulation experiment for compensation of instantaneous voltage sag is achieved. The experiment circuit is built using a signal conditioning circuit, a DSP controlling circuit, a power conversion circuit and a SMES unit. Analysis of the voltage waveforms before and after compensation validates that this SMES system is able to compensate instantaneous voltage sag.

Study of Control Algorithm for Indirect Stabilized Optical Seeker

Indirect stabilization technology can make the optical seeker lower cost and more compact, but it will also decrease the system’s performance. In order to improve the line-of-sight (LOS) stabilization precision, the indirect stabilized seeker’s model and loop control algorithm must be deeply studied. In this paper, the dynamic model of LOS coordinate frame is created according to the working principle of indirect stabilization system; A new no-angle-error control scheme was proposed. For severse disturbance environment, a feedforward torque compensation control algorithm was proposed based on disturbance torque estimation. The simulation and experiment results show that the proposed control approach can make the system tracking the instruction angular rate quickly and exactly, and also have the strong disturbance resistance ability. The study result will have great significance to the indirect stabilization technology’s theory study and engineering application.

Stress relaxation of narrow molar mass distribution polystyrene following uniaxial extension

The stress in the startup of uniaxial elongational flow until steady state, followed by stress relaxation, has been measured for a narrow molar mass distribution polystyrene melt with a molecular weight of 145kg∕mol. The experiments are conducted on a filament stretching rheometer, where a closed loop control of the midfilament diameter ensures controlled uniaxial extension. The closed loop control algorithm is extended to apply to the stress relaxation part of the experiment. It ensures a constant midfilament diameter, by controlling the motion of the end plates. By dividing the measured stress with the theoretically predicted stress from the Doi and Edwards model during relaxation, the stretch factors corresponding to each imposed stretch rate are obtained. These stretch factors converge to a unique envelope and eventually converge to unity for long times for all measured elongational rates.

Active noise control for double glazing

Implementation of ANC on double glazing windows has been investigated through controlling the volume of the air gap between the two window panes. In past work, the major problem was the location (generally in the middle of the glass plane) and/or efficiency of the transducer generating the counter noise. A new transducer (called strip-transducer) overcomes this problem by locating the loudspeaker system in the window frame. The transducer consists of a beam like rigid membrane (less than 20 mm width and 500 mm length) attached to a longitudinal voice coil suspended in the magnetic field generated by a set of magnets located in a metallic U-shaped profile. These strip-transducers are driven by a local ANC control loop, the reference sensor being either a microphone or an accelerometer located in the emitting side and the error microphone being located on the receiving side. The control loop algorithm is based on TechnoFirsts patented cloverleaf filter, allowing a faster response than traditional X-LMS algorithms. The transducer design uses the concept of tuned membrane resonator (TMR) to reduce the drive energy needed. A prototype using this new concept is under experimentation and has shown very encouraging results.

Comparative performance of linear and nonlinear neural networks to predict irregular breathing

Breathing adaptation during external-beam radiotherapy is a matter of great concern because uncompensated tumour motion requires extended treatment margins that endanger sensitive tissue. Compensation strategies include beam gating, collimator tracking and robotic beam re-alignment. All of these schemes have a system latency of up to several hundred milliseconds, which calls in turn for predictive control loops. Irregularities in breathing make prediction difficult. We have evaluated the performance of two classes of control loop algorithms—the linear adaptive filter and the adaptive nonlinear neural network—for highly irregular patient breathing behaviours. The neural network demonstrated robust adaptability to all of the observed breathing patterns while the linear filter failed in a significant percentage of cases. For those cases where the linear filter could function, it made less accurate predictions than the neural network. Because the neural network presents no additional computational burden in the control loop we conclude that it is the preferred choice among heuristic predictive algorithms.

Implementation of Low Cost and Advanced Slotless Brushless DC Motor Drive Using PLL Algorithm

In this article, in order to enhance the performance of Hall-ICs, a position signal synthesize control algorithm is developed. Also, considering diagnosis of permanent magnet brushless DC (PM BLDC) motor control and safety operation or system protection in case of having trouble and fault in one of Hall-ICs during operation, the developed two Hall-IC control scheme is applied. With the position signal of phase lock loop (PLL) control algorithm and the remainder scheme, one can operate the slotless PM BLDC motor in high performance.

Implementation of phase-locked loop control for MEMS scanning mirror using DSP

The present study has employed the phase-locked loop control method to ensure the operating of MEMS actuators at their resonant frequency. In this study, the control algorism was simulated by the MATLAB. Further, the digital signal processing (DSP) technique was adopted to implement the concept of phase-locked loop control algorithm. Thus, a wide VCO lock-in dynamic range was achieved. In applications, the optical scanners fabricated using the SOI wafer and MOSBE process were respectively employed to demonstrate the present technique. The test show that the resonant frequency was tracked for various driving voltages, loop gains, and initial frequency offsets. Thus, the variation of the scanning angle resulted from the offset of the resonant frequency of the devices can be prevented.

Control of the road tunnel CO density by a feedforward algorithm

For a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution below the required level. To control the tunnel pollution, a closed loop control algorithm may be used. A feedforward prediction algorithm and a cascade control algorithm were developed to regulate the CO level in a tunnel. The feedforward prediction algorithm composed of a traffic estimation algorithm and a CO density prediction algorithm, and the cascade control algorithm composed of a jet fan control algorithm and an air velocity setpoint algorithm. The verification of control algorithms was carried out by dynamic models developed from actual tunnel data. Simulation results showed that control algorithms developed for this research may be effective for the control of the tunnel ventilation system. (A) This paper was presented at Safety in the underground space - Proceedings of the ITA-AITES 2006 World Tunnel Congress and the 32nd ITA General Assembly, Seoul, Korea, 22-27 April 2006. For the covering abstract see ITRD E129148. Reprinted with permission from Elsevier.

CONTROL OF VORTEX SHEDDING BEHIND A CIRCULAR CYLINDER USING ELECTROMAGNETIC FORCES

Both open and closed loop control algorithms have been developed for manipulating wake flows past a solid cylinder in an electrically low-conducting fluid. The intent is to avoid vortex shedding and flow separation from the body, which is achieved through the introduction of localized electromagnetic forces (Lorentz forces) in the azimuthal direction generated by an array of permanent magnets and electrodes on the surface of the circular cylinder. The array of actuators offers the advantage of making the Lorentz force time and space dependent. More specifically, one closed loop control method has been derived from the equations of motion capable of determining at all times the intensity of the Lorentz force in order to control the flow. This is accomplished first, independently of the flow (open loop algorithm) and second, based on some partial flow information measured on the surface of the solid body (closed loop algorithm).

Dynamic optimization in future cellular networks

With multiple air-interface support capabilities and higher cell densities, future cellular networks will offer a diverse spectrum of user services. The resulting dynamics in traffic load and resource demand will challenge present control loop algorithms. In addition, frequent upgrades in the network infrastructure will substantially increase the network operation costs if done using current optimization methodology. This motivates the development of dynamic control algorithms that can automatically adjust the network to changes in both traffic and network conditions and autonomously adapt when new cells are added to the system. Bell Labs is pursuing efforts to realize such algorithms with research on near-term approaches that benefit present third-generation (3G) systems and the development of control features for future networks that perform dynamic parameter adjustment across protocol layers. In this paper, we describe the development of conceptual approaches, algorithms, modeling, simulation, and real-time measurements that provide the foundation for future dynamic network optimization techniques.

Gaming machine with automatic sound level adjustment and method therefor

A system and method for automatically adjusting the sound volume of a gaming machine based on the ambient noise level to an appropriate level. The gaming machine may implement an open loop control algorithm when the machine's sound output is inactive as determined, e.g., by software, or by analyzing samples from a soundboard. A closed loop control algorithm may be implemented when the gaming machine is active. Alternatively, the machine may implement only an open loop algorithm that provides volume adjustment only when the machine's sound output is inactive, in which case the adjusted volume is maintained through an active period, then adjusted again at the next inactive period. A saturation back off feature prevents the sound level of the gaming machine from escalating to, and remains at, a maximum, saturation level.

Yield improvement via minimisation of step height non-uniformity in chemical mechanical planarisation (CMP) with pressure and velocity as control variables

Obtaining local and global planarities is one of the prime criteria in dielectric and metal planarisations. Although chemical mechanical planarisation (CMP) helps us achieve these criteria in constant pattern density surfaces, the same is not true for variable pattern density surfaces. This results in formation of global step heights across the die. This paper provides open loop control algorithms for obtaining planarity across a die containing variations in pattern densities. Zonal pressure and/or velocity variations are used as control variables for this purpose. Based on the variation of pattern density and surface heights across the die, the surfaces are separated into zones and the pressure and velocity in individual zones are varied spatially and temporally. It is observed from simulations that the proposed algorithm can significantly improve the local and global planarities. The zonal pressure control improves the upper surface uniformity, whereas zonal velocity control significantly increases step height uniformity. The advantageous features of these two schemes are then combined to simultaneously maximise upper surface uniformity, and minimise step heights across the entire die. Work is currently in progress on physical realisation of these algorithms.

Yield Improvement via minimization of step height non-uniformity in Chemical Mechanical Planarization (CMP)

AbstractObtaining local and global planarity is one of the prime criteria in dielectric and metal planarizations. Although Chemical Mechanical Planarization (CMP) helps us achieve this criterion in constant pattern density surfaces, the same is not true for variable pattern density surfaces this results in formation of global step heights across the die. This paper provides a pressure open loop control algorithms for obtaining planarity across a die containing variations in pattern densities. Based on the variation of pattern density and surface heights across the die, the surfaces are separated into zones and the pressure is varied spatially and/or temporally to obtain uniform surface heights, with enhanced step height uniformity. One of the algorithms looks ahead and recalculates/modifies the pressure values by identifying the step heights that could be formed after a specified time step. The final surface predictions have improved uniformity on the upper surface as well as on the step heights across the entire die. The simulation would help us track the polishing process for each time step and guide us with the optimized pressure values that can be applied in order to an uniform final surface evolution.

Adaptive control of a composite cantilever beam with piezoelectric damping-modal actuators/sensors

Modeling and vibration control of a smart beam is investigated using piezoelectric damping-modal actuators/sensors. Theoretical formulations based on damping-modal actuator/sensors and numerical solutions are presented for the analysis of laminated composite beam with integrated sensors and actuators. Emphasis in this study is also given to the fiber orientation and the effect of actuator location on the control system. An instantaneous optimal close loop control algorithm coupling the direct and inverse piezoelectric effect is presented and used as an adaptive shape control of the dynamic response of the integrated laminated structure. An illustrative example, vibration control of large flexible structures is performed. A good correspondence has been obtained in all the examined results.