Control Design for Relative Stability in a PWM-Controlled Pneumatic System

2003 ◽  
Vol 125 (3) ◽  
pp. 504-508 ◽  
Author(s):  
Eric J. Barth, ◽  
Jianlong Zhang, and ◽  
Michael Goldfarb

This paper presents a control design methodology that provides a prescribed degree of stability robustness for plants characterized by discontinuous (i.e., switching) dynamics. The proposed control methodology transforms a discontinuous switching model into a linear continuous equivalent model, so that loop-shaping methods may be utilized to provide a prescribed degree of stability robustness. The approach is specifically targeted at pneumatically actuated servo systems that are controlled by solenoid valves and do not incorporate pressure sensors. Experimental demonstration of the approach validates model equivalence and demonstrates good tracking performance.

2001 ◽  
Author(s):  
Eric J. Barth ◽  
Jianlong Zhang ◽  
Michael Goldfarb

Abstract This paper presents a rigorous analysis and design method for PWM-based control of pneumatic systems. An equivalent analytical model incorporating the effects of a finite PWM switching period is formulated. This equivalent model was motivated by a lack of control design and analysis techniques needed to treat the inherently non-analytical switching models associated with PWM-based systems. The equivalent model enables the design of a loop compensator that rigorously addresses control design issues of stability robustness, disturbance rejection, insensitivity to sensor noise, performance bandwidth and actuator saturation. Simulation of this compensator with both the equivalent design model and a full nonlinear switching model for a particular pneumatic robot application is presented which demonstrates and validates the proposed method.


2021 ◽  
Vol 6 (1) ◽  
pp. 34
Author(s):  
Serigne Modou Die Mbacke ◽  
Mohammed El Gibari ◽  
Benjamin Lauzier ◽  
Chantal Gautier ◽  
Hongwu Li

Implantable pressure sensors represent an important part of the research activity in laboratories. Unfortunately, their use is limited by cost, autonomy and temperature-related drifts. The cost of use depends on several parameters, particularly their low battery life and the need for miniaturization to be able to implant the animals and monitor them over a time that is long enough to be physiologically relevant. This paper studied the possibility of reducing the thermal drift of implantable sensors. To quantify and compensate for the thermal drift, we developed the equivalent model of the piezoresistive probe by using the Cadence software. Our model takes into account the temperature (34–39 °C) as well as the pressure (0–300 mmHg). We were thus able to identify the source of the drift and thanks to our model, we were able to compensate for it thanks to the compensation circuits added to the conditioning circuits of the sensor. The maximum relative drift of the sensor is (0.1 mV/°C)/3.6 mV (2.7%), a drift of the conditioning circuit is (0.98 mV/°C)/916 mV (0.1%) and the whole is (13.4 mV/°C)/420 mV (32%). The compensated sensor shows a relative maximum drift of (0.371 mV/°C)/405 mV (0.09%). The output voltage remains stable over the measurement temperature range.


Author(s):  
Zeyuan Li ◽  
Wennong Zhang ◽  
Yihuang Zhang ◽  
Xiang Xu

Author(s):  
Michel Joël Tchatchueng Kammegne ◽  
Yvan Tondji ◽  
Ruxandra Mihaela Botez ◽  
Lucian Teodor Grigorie ◽  
Mahmoud Mamou ◽  
...  

A morphing wing can improve the aircraft aerodynamic performance by changing the wing airfoil depending on the flight conditions. In this paper, a new control methodology is presented for a morphing wing demonstrator tested in a subsonic wind tunnel in the open-loop configuration. Actuators integrated inside the wing are used to modify the flexible structure, which is an integral part of the wing. In this project, the actuators are made in-house and controlled with logic control, which is developed within the main frame of this work. The characterization of the flow (laminar or turbulent) over the wing is obtained starting from the pressure signals measured over the flexible part of the wing (upper surface). The signals are acquired by using some pressure sensors (Kulite sensors) incorporated in this flexible part of the wing upper surface. The technique used to collect Kulite pressure data and the post-processing methodology are explained. The recorded pressure data are sometimes subjected to noise, which is filtered before being processed. The standard deviation and power spectrum visualization of the pressure data approaches are used to evaluate the quality of the flow over the wing and estimate the transition point position in the area monitored by the Kulite sensors. In addition, infrared thermography visualization is implemented to observe the transition region over the entire wing upper surface, and to validate the methodology applied to the pressure data in this way. The demonstrator measures 1.5 m chordwise and 1.5 m spanwise. Four miniature actuators fixed on two actuation lines are used to morph the wing. The wing is also equipped with a rigid aileron. The experimental aerodynamic results obtained after post processing validate the numerical prediction for the transition location.


Author(s):  
Perry Y. Li

Angle-domain repetitive disturbances refer to disturbances that are periodic in a generic angle variable which is monotonically increasing with time but not uniformly. This paper extends the classical prototype repetitive control methodology for time periodic disturbances to this situation. Instead of using an internal model approach to derive the control, an affine parameterization approach is adopted which reduces the control design methodology to one of estimating and canceling the disturbance. While the resulting control architectures are similar to the classical time-domain periodic case, the stability conditions are different and depend on the choice of signal norms. Compensator design for non-minimum phase plants also need to be modified. Robustness is also considered in the L2 setting and an affine Q-filter concept is introduced to achieve robust stability.


Author(s):  
Kevin B. Fite ◽  
Michael Goldfarb

This paper presents an architecture and control methodology for a multi-degree-of-freedom teleoperator system. The approach incorporates impedance control of the telemanipulator pair and formulates the system as a single feedback loop encompassing the human operator, telemanipulator, and remote environment. In so doing, multivariable Nyquist-like techniques are used to design compensation for enhanced stability robustness and performance. A measure of the transparency exhibited by the multivariable teleoperator system is attained using matrix singular values. The approach is experimentally demonstrated on a three degree-of-freedom scaled telemanipulator pair with a highly coupled environment. Using direct measurement of the power delivered to the operator to assess the system’s stability robustness, along with the proposed measure of multivariable transparency, the loop-shaping compensation is shown to improve the stability robustness by a factor of almost two and the transparency by more than a factor of five.


2020 ◽  
Vol 68 (5) ◽  
pp. 189-194
Author(s):  
Shinsuke Sakamoto ◽  
Takashi Shimomura ◽  
Sayaka Kanata

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