Hybrid Control For Aerospace Systems

Hybrid dynamical systems are dynamical systems in which continuous and discrete evolutions coexist and interact. Their twofold nature makes them particularly powerful for both describing and synthesizing complex dynamical behaviors. In this work we exploit this capability for designing innovative control and estimation algorithms that cope with challenges in aerospace applications. In particular: 1. we propose different impulsive control strategies for the problem of close-range rendezvous between two spacecrafts in elliptic orbits; 2. we design a robust time-sub-optimal controller for a class of linear systems emerging in aerospace applications where the control input is limited in magnitude; 3. we synthesize an observer to estimate the speed of rotary systems providing angular measurements that evolve on the unit circle. To this end, we make use of a recent formalism tailored to hybrid dynamical systems for both modeling and proving desirable properties of the proposed algorithms, which are as well confirmed by simulative and experimental validations

A Class of Hybrid Velocity Observers for Angular Measurements With Jumps

International audienceWe propose a hybrid nonlinear high-gain observer to estimate the speed of rotary systems equipped with potentiometer-based, capacitive or hall-effect rotary sensors or providing angular measurements evolving in S1, exhibiting unpredictable jumps of 2π. A hybrid measurement model is proposed, based on which a hybrid high-gain observer is synthesized, which does not require the knowledge of the jump times. Asymptotic tracking of the proposed observer is proven. A sampled-data approximation of the proposed observer is developed as well, based on which an experimental validation shows suitability for real-time applications

Benchmark model of Quanser's 3 DOF Helicopter

This paper proposes a software benchmark tool for the Quanser " 3 DOF Helicopter " in the Mathworks Simscape environment, based on a multi-body model of the experimental setup. The proposed benchmark tool takes into account a number of implementation features of the experimental setup and aims at providing a tool for simulative validation and performance analysis of control strategies. Along with this software-in-the-loop tool, a novel reduced complexity non-linear model for the Quanser " 3 DOF Helicopter " is derived from the Lagrangian description of the full multi-body model, with the scope of being used in the control synthesis phase. The identification of the models parameters is carried out following a " gray-box " type of paradigm in order to match the models with the experimental setup. A feedback linearizing control law is as well proposed, based on the reduced complexity model. Closed-loop experimental results both show the accuracy of the simulated response compared to the experimental response, and the effectiveness of the proposed control strategy in a set-point regulation task

Robust time-sub-optimal control of the saturated double integrator applied to attitude stabilization

International audienceThis paper proposes a robust time-sub-optimal controller for the double integrator with saturated input, based on a hybrid blend of a local and a global controller. The scheme makes use of two hysteresis mechanisms in order to provide robustness to unmodelled dynamics and measurement noise. Rigorous certificates of the stability of the proposed controller are given, by exploiting the properties of hybrid dynamical system established in recent works of Teel et al. Attitude stabilization with the proposed control strategy is then illustrated by simulations. The method shows its effectiveness in stabilizing the attitude, preventing the typical chattering and robustness issues emerging with classical time-optimal implementations

An LMI-based approach for the control of semi-active magnetorheological suspensions

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A hybrid control framework for impulsive control of satellite rendezvous

International audienceWe focus on the problem of satellite rendezvous between two spacecraft in elliptic orbits. Using a linearized model of the relative dynamics, we first propose a periodic similarity transformation based on Floquet-Lyapunov theory, leading to a set of coordinates under which the free motion is linear time-invariant. Then we address the problem of impulsive control of satellite rendezvous as a hybrid dynamical system, and we show that the arising elegant representation enables designing impulsive control laws with different trade-offs between computational complexity and fuel consumption. The adopted hybrid formalism allows us to prove suitable stability properties induced by the proposed controllers. The results are comparatively illustrated on simulation examples

A hybrid control framework for impulsive control of satellite rendezvous

International audienceWe focus on the problem of satellite rendezvous between two spacecraft in elliptic orbits. Using a linearized model of the relative dynamics, we first propose a periodic similarity transformation based on Floquet-Lyapunov theory, leading to a set of coordinates under which the free motion is linear time-invariant. Then we address the problem of impulsive control of satellite rendezvous as a hybrid dynamical system, and we show that the arising elegant representation enables designing impulsive control laws with different trade-offs between computational complexity and fuel consumption. The adopted hybrid formalism allows us to prove suitable stability properties of the proposed controllers. The results are comparatively illustrated on simulation examples

Position and speed control of a low-cost two-wheeled, self-balancing inverted pendulum vehicle

International audienceIn this paper we present a low-cost prototype of a two-wheeled, self-balancing inverted pendulum realized at the mechatronics laboratory of the University of Trento. This vehicle lends itself to represent a class of control problems that arise in many educational robotic devices custom built and assembled with low-end market components. We provide a detailed description of the equipment and describe the strategies adopted to suitably address backlash of the low-cost DC motors and disturbances arising from the voltage controlled hardware. Then we propose a nested control paradigm where an inner loop provides regulation of a virtual control requested by an outer loop that uses the pitch angle to regulate the longitudinal displacement and speed. Three saturation-based control laws are proposed for the outer loop, all of them allowing the designer to adjust the maximum pitch angle. Experimental results illustrate the effectiveness of the proposed control laws and the operation of the developed prototype

Geniale cbersetzungen. Goethe \u2013 Benjamin \u2013 Spengler

Morphology and metamorphosis are analyzed as ways of genial translations. In the case of Goethe as a translation of natural rules into artistical rules (Faust), in that of Spengler and Benjamin as that of natural morphology into proceedings of philosophy of history. Metamorphosis and translation are ways of mediation between different fields of scientific and cultural activities. Moreover, they represent a mimetic and intuitive way of dealing with problems which does not transcend into mere logical thought. This part is treated also in reference to Aristotle and Hegel. At the end the approaches of Benjamin and Spengler are briefly criticized and compared in reference to their Goethean origin and to the difference between their outcome and solutions