Intelligent Adaptive Motion Control for Ground Wheeled Vehicles

In this paper a new intelligent adaptive control is applied to solve a problem of motion control of ground vehicles with two independent wheels actuated by a differential drive. The major objective of this work is to obtain a motion control system by using a new fuzzy inference mechanism where the Lyapunov’s stability can be assured. In particular the parameters of the kinematical control law are obtained using an intelligent Fuzzy mechanism, where the properties of the Fuzzy maps have been established to have the stability above. Due to the nonlinear map of the intelligent fuzzy inference mechanism (i.e. fuzzy rules and value of the rule), the parameters above are not constant, but, time after time, based on empirical fuzzy rules, they are updated in function of the values of the tracking errors. Since the fuzzy maps are adjusted based on the control performances, the parameters updating assures a robustness and fast convergence of the tracking errors. Also, since the vehicle dynamics and kinematics can be completely unknown, a dynamical and kinematical adaptive control is added. The proposed fuzzy controller has been implemented for a real nonholonomic electrical vehicle. Therefore system robustness and stability performance are verified through simulations and experimental studies

Noise control and utility: From regulatory network to spatial patterning

Stochasticity (or noise) at cellular and molecular levels has been observed extensively as a universal feature for living systems. However, how living systems deal with noise while performing desirable biological functions remains a major mystery. Regulatory network configurations, such as their topology and timescale, are shown to be critical in attenuating noise, and noise is also found to facilitate cell fate decision. Here we review major recent findings on noise attenuation through regulatory control, the benefit of noise via noise-induced cellular plasticity during developmental patterning, and summarize key principles underlying noise control

Robust control of a bimorph mirror for adaptive optics system

We apply robust control technics to an adaptive optics system including a dynamic model of the deformable mirror. The dynamic model of the mirror is a modification of the usual plate equation. We propose also a state-space approach to model the turbulent phase. A continuous time control of our model is suggested taking into account the frequential behavior of the turbulent phase. An H_\infty controller is designed in an infinite dimensional setting. Due to the multivariable nature of the control problem involved in adaptive optics systems, a significant improvement is obtained with respect to traditional single input single output methods

Robust multivariable predictive control: how can it be applied to industrial test stands ?

To cope with recent technological evolutions of air conditioning systems for aircraft, the French Aeronautical Test Center built a new test stand for certification at ground level. The constraints specified by the industrial users of the process seemed antagonistic for many reasons. First, the controller had to be implemented on an industrial automaton, not adaptable to modern algorithms. Then the specified dynamic performances were very demanding, especially taking into account the wide operating ranges of the process. Finally, the proposed controller had to be easy for nonspecialist users to handle. Thus, the control design and implementation steps had to be conducted considering both theoretical and technical aspects. This finally led to the development of a new multivariable predictive controller, called alpha-MPC, whose main characteristic is the introduction of an extra tuning parameter alpha that has enhanced the overall control robustness. In particular, the H1-norm of the sensitivity functions can be significantly reduced by tuning this single new parameter. It turns out to be a simple but efficient way to improve the robustness of the initial algorithm. The other classical tuning parameters are still physically meaningful, as is usual with predictive techniques. The initial results are very promising and this controller has already been adopted by the industrial users as the basis of the control part for future developments of the test stand

Adaptive Control: Actual Status and Trends

Important progress in research and application of Adaptive Control Systems has been achieved in the last ten years. The techniques which are currently used in applications will be reviewed. Theoretical aspects currently under investigation and which are related to the application of adaptive control techniques in various fields will be briefly discussed. Applications in various areas will be briefly reviewed. The use of adaptive techniques for vibrations monitoring and active vibration control will be emphasized

Adaptive feedforward cancellation viewed from an oscillator amplitude control perspective

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. 335-340).This thesis presents methods of characterizing the convergence, error, stability, and robustness properties of Adaptive Feedforward Cancellation (AFC) for use on fast tool servos in high-precision turning applications. Previous work has shown that classical control techniques can be used to analyze the stability and robustness of an AFC loop. However, determination of the convergence and error properties of the closed-loop system to changes in the reference or disturbance signal is not an obvious output of these analyses. We have developed a method of viewing AFC from an oscillator amplitude control (OAC) perspective, which provides additional use of classical control techniques to determine the convergence and error properties of the closed-loop system. AFC is a form of repetitive control that can be used to significantly improve periodic trajectory following/disturbance rejection. Fast tool servos used in high-precision turning applications commonly follow periodic trajectories and develop large errors, which usually occur at integer harmonics of the fundamental spindle rotation frequency. We have developed a loop-shaping approach to designing multiple resonator AFC controllers and have implemented this design on a commercially available piezoelectric (PZ) driven FTS using a PC-based digital control system. Our view of Adaptive Feedforward Cancellation from an oscillator amplitude control perspective builds upon previous work in the literature. We use an averaging analysis to simplify the single resonator AFC system into two coupled single-input single-output (SISO) oscillator amplitude control loops and show that by using the correct rotation matrix, these loops are effectively decoupled. This simplification provides the use of classical control techniques to approximate the dynamics of the closedloop output to changes in the amplitude or frequency of the reference/disturbance signal. The simulated and experimental results conform well to our analytical predictions for sufficiently low gain values.by Joseph Harry Cattell.S.M