An electro-pneumatic control system and single op-amp PID control circuit is provided for regulating the output pressure response provided to a load. The control system includes a control valve for producing a control pressure signal and a booster for providing an output pressure response to a pneumatic load in accordance with the control pressure signal. A pressure sensor is further provided for measuring the output pressure response provided to the load and for generating a corresponding feedback voltage signal provided to the control circuit. The control circuit compares the feedback signal to a command signal input in accordance with a predetermined transfer function having proportional, integral and derivative (PID) components, and generates a control voltage signal for stably controlling the output pressure response provided to the load.

Electro-pneumatic control system and PID control circuit

An active low-pass filter suitable as a 90° phase shifter circuit is provided which requires few external components when formed as an IC. The current resulting from the input signal outputted from a first impedance element is amplified by a first current amplifier, and the resulting output current is converted by a first converting means to a voltage, which is supplied via a second impedance element to a second current amplifier; the output current of the second current amplifier is converted by a second converting means to a voltage, which is outputted as a filter output, while the current corresponding to the output voltage of the second converting means is negatively fed back into the inputs of the first and second current amplifiers; furthermore, at least the current amplification factor of the first current amplifier is made controllable, thereby permitting the cut-off frequency to be varied arbitrarily.

Active low-pass filter

Linear high gain (greater than 20 dB) and high power (greater than +20 dbm) devices for RF power amplifiers are achieved using either fully monolithic or hybridized versions of silicon MMIC two-stage cascaded amplifiers. The device features three feedback loops in conjunction with a DC biasing network. Resistor-capacitor feedback circuits utilize only two capacitiveelements Cblock, Cf6 which are provided as a single three-terminal element having a common lower plate.

High gain monolithic microwave integrated circuit amplifier

of the Disclosure A circuit including a conventional digital-to-analog converter (DAC) and a charge pump for producing an analog representation of an input waveform defined by an input digital bit stream, the analog representa-tion being relatively free of spurious aberrations usually present in the output of a conventional DAC. The charge pump and an associated integrator are used to produce a first approximation of the input waveform and the DAC and an associated detuned slew-rate filter are used to maintain the first approximation in long-term conformance with a more accurate second approxima-tion. Spurious aberrations in the second approximation are integrated over several steps of the input bit stream, thereby minimizing their adverse impact on the relatively true first approximation.

Charge-pump glitch filter

This variable gain amplifier is provided with an operational amplifier. The non-inversion input terminal of the operational amplifier is connected to a reference potential. A feedback resistor is connected between the output terminal and inversion input terminal of the operational amplifier. An input resistor is inserted between the inversion input terminal of the operational amplifier and the input terminal of the variable gain amplifier circuit. An adjustment resistor is connected between the inversion input terminal of the operational amplifier and the reference potential. The resistance value of the adjustment resistor is controlled in such a way as to maintain constant against the resistance value change a combined resistance value in its parallel connection with the input resistor when changing the resistance value of the input resistor.

Variable gain amplifier circuit and filter circuit

An electronic filter comprised of three active filter sections (A, B, C) is provided to smooth the stepped signal from a digital-to-analog converter The first section has a noninverting low-pass filter transfer function, and the second has an inverting transfer function designed to pass a narrow frequency band centered at the step frequency of the stepped output signal with sharp cutoff on either side of that narrow band The third section adds the noninverted output of the first section to the inverted output of the second section This third section has a lead-lag transfer function designed to reduce the phase angle between the signal at its output terminal and the stepped signal at the input of the first section

Smoothing filter for digital to analog conversion

When designing a flight simulator, providing a set of low mass variable-characteristic pilot controls can be very difficult. Thus, a strong incentive exists to identify the highest possible mass that will not degrade the validity of a simulation. The NASA Dryden Flight Research Center has conducted a brief flight program to determine the maximum acceptable mass (system inertia) of an aircraft sidearm controller as a function of force gradient. This information is useful for control system design in aircraft as well as development of suitable flight simulator controls. A modified Learjet with a variable-characteristic sidearm controller was used to obtain data. A boundary was defined between mass considered acceptable and mass considered unacceptable to the pilot. This boundary is defined as a function of force gradient over a range of natural frequencies. This investigation is limited to a study of mass-frequency characteristics only. Results of this investigation are presented in this paper.

https://www.nasa.gov/centers/dryden/pdf/88340main_H-2014.pdf

Charles A. Wagner

Papers

Smoothing filter for digital to analog conversion

Effects of mass on aircraft sidearm controller characteristics