scholarly journals Phase Compensation Strategies for Modulated-Demodulated Control With Application to Pulsed Jet Injection

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Cory Hendrickson ◽  
Robert T. M’Closkey
Keyword(s):  
Disturbance Rejection ◽  
Jet Injection ◽  
Phase Compensation ◽  
Reference Tracking ◽  
Pulsed Jet ◽  
Control Frequency ◽  
Dynamic Phase ◽  
Compensation Methods ◽  
Aerospace Systems ◽  
Periodic Signals

Modulated-demodulated control is an effective method for asymptotic disturbance rejection and reference tracking of periodic signals, however, conventional static phase compensation often limits the loop gain in order to avoid sensitivity function peaking in a neighborhood of the frequencies targeted for rejection or tracking. This paper introduces dynamic phase compensation for modulated-demodulated control which improves disturbance rejection characteristics by inverting the plant phase in a neighborhood of the control frequency. Dynamic phase compensation is implemented at baseband which enables the use of low-bandwidth compensators to invert high frequency dynamics. Both static and dynamic phase compensation methods are used to demonstrate a novel application of repetitive control for pulsed jet injection. In this application pulsing an injectant has been shown to produce advantageous effects such as increased mixing in many energy generation and aerospace systems. The sharpness of the pulse can have a large impact on the effectiveness of control. Modulated-demodulated control is used to maximize the sharpness of a pulsed jet of air using active forcing by tracking a square wave in the jet’s temporal velocity profile.

A Design of the Beam-Adjustable Metasurface Based on the Plasma Metamaterial with the Dielectric Matching Layers

Frequenz ◽  
2019 ◽  
Vol 73 (3-4) ◽  
pp. 89-97
Author(s):  
Hai-Feng Zhang ◽  
Yu Ma ◽  
Hao Zhang
Keyword(s):  
Phase Curve ◽  
Refractive Indices ◽  
The Novel ◽  
Phase Compensation ◽  
Matching Layer ◽  
Excitation Region ◽  
Compensation Methods ◽  
Spatial Beam ◽  
Layer Technique ◽  
Simulation Results

Abstract In this paper, a beam-adjustable metasurface (BAM) is realized based on the plasma metamaterial with a dielectric matching layer technique, which is a novel phase compensation method. In order to realize phase compensation from 0° to 360°, the dielectric matching layers are added above the BAM to compensate the phase. The added dielectric layers can have different refractive indices or different thicknesses. Compared with the conventional phase compensation methods, such a method has an universal adaptability, and the phase curve of unit cell does not need to cover 0° ~ 360°. The elements of the BAM can be reconstructed by adjusting the excitation region of the plasma resonance structures to achieve spatial beam scanning. The simulation results show that the proposed BAM has a good performance. It provides that such a novel idea can help to design the novel BAMs to obtain the adjustable and scannable reflective beam in space.

Numerical simulations of high frequency transverse pulsed jet injection into a supersonic crossflow

2020 ◽  
Vol 103 ◽  
pp. 105908 ◽  
Author(s):  
Nehemiah J. Williams ◽  
Trevor M. Moeller ◽  
Richard J. Thompson
Keyword(s):  
Numerical Simulations ◽  
High Frequency ◽  
Jet Injection ◽  
Pulsed Jet

High-Precision Cutting Tool Tracking With a Magnetic Bearing Spindle

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Alexander Smirnov ◽  
Alexander H. Pesch ◽  
Olli Pyrhönen ◽  
Jerzy T. Sawicki
Keyword(s):  
Pid Control ◽  
Disturbance Rejection ◽  
High Speed ◽  
Cutting Tool ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
External Loading ◽  
Reference Tracking ◽  
Tool Position ◽  
Tool Tracking

A method is presented for tool tracking in active magnetic bearing (AMB) spindle applications. The method uses control of the AMB air gap to achieve the desired tool position. The reference tracking problem is transformed from the tool coordinates into the AMB control axes by bearing deflection optimization. Therefore, tool tracking can be achieved by an off-the-shelf AMB controller. The method is demonstrated on a high-speed AMB boring spindle with a proportional integral derivative (PID) control. The hypothetical part geometries are traced in the range of 30 μm. Static external loading is applied to the tool to confirm disturbance rejection. Finally, a numerical simulation is performed to verify the ability to control the tool during high-speed machining.

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