Stability control of nonlinear micromechanical resonators under simultaneous primary and superharmonic resonances

Fast effects of a slow excitation on the main resonance of a nonlinear micromechanical resonator are analytically and experimentally investigated. We show, in particular, how the bifurcation topology of an undesirable unstable behavior is modified when the resonator is simultaneously actuated at its primary and superharmonic resonances. A stabilization mechanism is proposed and demonstrated by increasing the superharmonic excitation

Geometric Mechanics, Stability and Control

This paper gives an overview of selected topics in mechanics and their relation to questions of stability, control and stabilization. The mechanical connection, whose holonomy gives phases and that plays an important role in block diagonalization, provides a unifying theme

FLIGHT-DETERMINED STABILITY AND CONTROL DERIVATIVES OF A SUPERSONIC AIRPLANE WITH A LOW-ASPECT-RATIO UNSWEPT WING AND A TEE-TAIL

Flight-determined stability & control derivatives of supersonic aircraft with low aspect ratio unswept wing & t-tai

Large-scale wind-tunnel tests of descent performance of an airplane model with a tilt wing and differential propeller thrust

Wind tunnel tests of wing stall, performance, and longitudinal stability & control of large model v/stol tilt wing transport aircraf

DIAGRAMS, FUNCTIONAL AND CONSTRUCTIVE SOLUTIONS OF THE STABILITY CONTROL SYSTEMS FOR AUTOMOTIVE APPLICATION

The modern car must correspond to certain requirements regarding the driver safety and more than that it must convince the potential buyer that it will offer him the safety he is so much in need of. For that reason the number and the diversity of the safety systems have increased so fast. Despite all this for the time being it can not be stated that a particular vehicle is totally safe and it can come through any difficult situation. Because of that the research in the field is carried on and the number of those who propose solutions mend to improve the vehicle behavior is getting bigger.active safety, vehicle, control

The Uptake and Expected Impact of Electronic Stability Control (ESC) amongst the Australian Passenger Vehicle Fleet

Electronic Stability Program (ESP) is an in-vehicle active control system which acts in loss of control situations to stabilise a vehicle. Several studies have shown the road safety benefits of ESP in international contexts. However, little consideration has been given for factors which may inhibit the uptake and potential effectiveness of ESP amongst the Australian vehicle fleet. This study highlights some of these potential factors including the rate of uptake of ESP into the Australian new vehicle market, purchasing patterns, driver behaviour, culture and the media. Conclusions are drawn in terms of future research directions and good public policy to maximise the effects of ESP in Australia

Fuzzy Logic Approach to Stability Control

Traditional Electronic Stability Control (ESC) for automobiles is usually accomplished through the use of estimated vehicle dynamics from simplified models. Starting with the conventional two degree-of-freedom vehicle model, one can estimate the vehicle states from the driver steering input. From this estimate, vehicle sideslip angle can be found and this is generally used with a threshold value to initiate a control action. The input/output relationship of the model depends heavily on the accuracy of the parameters used and various means to correct model inaccuracies. Specifically, these models depend on the tire cornering stiffness which is prone to change with age and loading of the tires. Moreover, not all consumers will replace the original equipment (OE) tires with the same ones. Vehicle response is also directly related to coefficient of friction between the tire and road which varies with road and tire conditions. These issues may result in the degradation of the effectiveness of the ESC system. At the very least, they may require extensive tuning of the control algorithms. This thesis proposes a different method for estimating the instability of a vehicle. It is solely based on measurable vehicle dynamic response characteristics including lateral acceleration, yaw rate, speed, and driver steering input. These signals are appropriately conditioned and evaluated with fuzzy logic to determine the degree of instability present. When the \u27degree of instability\u27 passes a certain threshold, the appropriate control action is applied to the vehicle in the form of differential yaw braking. Using only the measured response of the vehicle alleviates the problem of degraded performance when vehicle parameters change. Finally, ten case studies of different vehicles, configurations, environments, driver models, and maneuvers are tested with the same ESC strategy to examine the concept of stability control without estimation. Four very different vehicles ranging from a sports car to a sport utility vehicle (SUV) in multiple configurations including degraded rear tires and different loading conditions are used in evaluating the proposed ESC. These vehicles and configurations are subjected to multiple maneuvers including a double lane change and a fishhook maneuver with tire-to-road conditions such as split mu and low mu to simulate slippery road conditions. The main result of this research is the evolution of a new ESC concept where performance is not based on a vehicle model with set parameters that lose effectiveness in estimating the vehicle dynamic states when the vehicle changes. Instead, the algorithm relies only on the current measurable dynamic states of the vehicle to preserve stability