Control of the reaching mode in variable structure systems

This paper focuses on the behaviour of variable structure systems with dynamic control, particularly during the reaching mode of operation. It is shown that stability problems may arise during this reaching phase. The causes of these problems are closely related with the problems of windup commonly found in conventional control systems with actuator constraints. Methods for stabilization of the reaching mode are proposed which are based on the concepts of 'realizable reference' and observers. Well-known algorithms that have been previously proposed from empiric ideas, can now be rigorously derived using these concepts. The theoretical framework developed by Kothare and co-workers in the context of windup is generalized to study and design control algorithms for the reaching mode

Control of the reaching mode in variable structure systems

This paper focuses on the behaviour of variable structure systems with dynamic control, particularly during the reaching mode of operation. It is shown that stability problems may arise during this reaching phase. The causes of these problems are closely related with the problems of windup commonly found in conventional control systems with actuator constraints. Methods for stabilization of the reaching mode are proposed which are based on the concepts of 'realizable reference' and observers. Well-known algorithms that have been previously proposed from empiric ideas, can now be rigorously derived using these concepts. The theoretical framework developed by Kothare and co-workers in the context of windup is generalized to study and design control algorithms for the reaching mode.Facultad de Ingenierí

Modified PSO based PID Sliding Mode Control using Improved Reaching Law for Nonlinear systems

In this paper, a new model based nonlinear control technique, called PID (Proportional-Integral-Derivative) type sliding surface based sliding mode control is designed using improved reaching law. To improve the performance of the second order nonlinear differential equations with unknown parameters modified particle swarm intelligent optimization (MPSO) is used for the optimized parameters. This paper throws light on the sliding surface design, on the proposed power rate exponential reaching law, parameters optimization using modified particle swarm optimization and highlights the important features of adding an integral term in the sliding mode such as robustness and higher convergence, through extensive mathematical modeling. Siding mode control law is derived using Lyapunov stability approach and its asymptotic stability is proved mathematically and simulations showing its validity. MPSO PID-type Sliding mode control will stabilize the highly nonlinear systems, will compensate disturbances and uncertainty and reduces tracking errors. Simulations and experimental application is done on the non-linear systems and are presented to make a quantitative comparison.Comment: arXiv admin note: substantial text overlap with arXiv:2207.1112

Vertical Take-Off and Landing Control via Dual-Quaternions and Sliding Mode

The landing and reusability of space vehicles is one of the driving forces into renewed interest in space utilization. For missions to planetary surfaces, this soft landing has been most commonly accomplished with parachutes. However, in spite of their simplicity, they are susceptible to parachute drift. This parachute drift makes it very difficult to predict where the vehicle will land, especially in a dense and windy atmosphere such as Earth. Instead, recent focus has been put into developing a powered landing through gimbaled thrust. This gimbaled thrust output is dependent on robust path planning and controls algorithms. Being able to have a powered landing with on-board real-time control algorithms is absolutely essential to exploring the solar system as it is the only effective way to bring heavy equipment or people to a planetary surface. A robust, efficient, and easy-to-use controls algorithm will be formulated to solve this controls problem known as the \emph{soft landing problem}. Through representing rigid body motion with dual-quaternions, translation and rotation can be represented in a single compact form that is free of singularities and provides the shortest path interpolation compared to any other formulation. These rigid bodies will be shown to follow a desired time-dependent orientation and position through one of the most powerful methods of modern control known for its accuracy, robustness, and easy tuning and implementation -- sliding mode control

Mariner IV Mission to Mars. Part I

This technical report is a series of individual papers documenting the Mariner-Mars project from its beginning in 1962 following the successful Mariner-Venus mission. Part I is pre-encounter data. It includes papers on the design, development, and testing of Mariner IV, as well as papers detailing methods of maintaining communication with and obtaining data from the spacecraft during flight, and expected results during encounter with Mars. Part 11, post-encounter data, to be published later, will consist of documentation of the events taking place during Mariner IV's encounter with Mars and thereafter. The Mariner-Mars mission, the culmination of an era of spacecraft development, has contributed much new technology to be used in future projects

Design of Sliding Mode PID Controller with Improved reaching laws for Nonlinear Systems

In this thesis, advanced design technique in sliding mode control (SMC) is presented with focus on PID (Proportional-Integral-Derivative) type Sliding surfaces based Sliding mode control with improved power rate exponential reaching law for Non-linear systems using Modified Particle Swarm Optimization (MPSO). To handle large non-linearities directly, sliding mode controller based on PID-type sliding surface has been designed in this work, where Integral term ensures fast finite convergence time. The controller parameter for various modified structures can be estimated using Modified PSO, which is used as an offline optimization technique. Various reaching law were implemented leading to the proposed improved exponential power rate reaching law, which also improves the finite convergence time. To implement the proposed algorithm, nonlinear mathematical model has to be decrypted without linearizing, and used for the simulation purposes. Their performance is studied using simulations to prove the proposed behavior. The problem of chattering has been overcome by using boundary method and also second order sliding mode method. PI-type sliding surface based second order sliding mode controller with PD surface based SMC compensation is also proposed and implemented. The proposed algorithms have been analyzed using Lyapunov stability criteria. The robustness of the method is provided using simulation results including disturbance and 10% variation in system parameters. Finally process control based hardware is implemented (conical tank system)

Control of the reaching mode in variable structure systems

This paper focuses on the behaviour of variable structure systems with dynamic control, particularly during the reaching mode of operation. It is shown that stability problems may arise during this reaching phase. The causes of these problems are closely related with the problems of windup commonly found in conventional control systems with actuator constraints. Methods for stabilization of the reaching mode are proposed which are based on the concepts of 'realizable reference' and observers. Well-known algorithms that have been previously proposed from empiric ideas, can now be rigorously derived using these concepts. The theoretical framework developed by Kothare and co-workers in the context of windup is generalized to study and design control algorithms for the reaching mode.Facultad de Ingenierí

Design of an Integral Suboptimal Second-Order Sliding Mode Controller for the Robust Motion Control of Robot Manipulators

The formulation of an integral suboptimal second-order sliding mode ((ISSOSM) control algorithm, oriented to solve motion control problems for robot manipulators, is presented in this paper. The proposed algorithm is designed so that the so-called reaching phase, normally present in the evolution of a system controlled via the sliding mode approach, is reduced to a minimum. This fact makes the algorithm more suitable to be applied to a real industrial robot, since it enhances its robustness, by extending it also to time intervals during which the classical sliding mode is not enforced. Moreover, since the algorithm generates second-order sliding modes, while the model of the controlled electromechanical system has a relative degree equal to one, the control action actually fed into the plant is continuous, which provides a positive chattering alleviation effect. The assessment of the proposal has been carried out by experimentally testing it on a COMAU SMART3-S2 anthropomorphic industrial robot manipulator. The satisfactory experimental results, also compared with those obtained with a standard proportional-derivative controller and with the original suboptimal algorithm, confirm that the new algorithm can actually be used in an industrial context

Multi-Path Automatic Ground Collision Avoidance System for Performance Limited Aircraft with Flight Tests: Project Have Medusa

A multi-path automatic ground collision avoidance system (Auto-GCAS) for performance limited aircraft was further developed and improved to prevent controlled flight into terrain. This research includes flight test results from the United States Test Pilot School\u27s Test Management Project (TMP) titled Have Multi-Path Escape Decisions Using Sophisticated Algorithms (MEDUSA). Currently, the bomber and mobility air- craft communities lack an Auto-GCAS. The F-16 Auto-GCAS was proven successful for fighter-type aircraft with seven aircraft and eight lives saved from 2014 to 2018. The newly developed and tested Rapidly Selectable Escape Trajectory (RSET) sys- tem included a 5-path implementation which continuously updated at a rate of up to 12.5 Hz. The research employed Level 1 Digital Terrain Elevation Data (DTED) to identify the offending terrain and an augmented 6 Degree-of-Freedom (DoF) Stitched aerodynamic model to create terrain avoidance paths based on the aircraft\u27s current state and location. The system then triggered when all paths predicted collision with the DTED and automatically activated the path which had the longest time until impact. A terrain safety buffer (TSB) of 200 ft added to the DTED to allowed for the time needed to process and execute the maneuver. The RSET system was flight tested against DTED using the Calspan Learjet 25D Variable Stability System (VSS). Path prediction error (PPE) did not meet the specified criteria and was larger than expected for the 30-second path predictions; however, at the maximum refresh rate of 12.5 Hz, the RSET system ensured terrain clearance in all cases tested. The RSET system was able to achieve and maintain target load factor and flight path angle with momentary overshoots. The system showed no tendency for nuisance. The RSET hand-back was favorable and can be used as a baseline for future Auto-GCASs

USPOREDBA EFIKASNOSTI SLIJEĐENJA TRAJEKTORIJE ROBOTA PRI UPOTREBI RAZLIČITIH METODA NELINEARNOG UPRAVLJANJA

The Denavit-Hartenberg algorithm and the Lagrange-Euler method are used to derive realistic kinematics and dynamic models of a three-axis electric driven articulated planar robot with viscous, dynamic and static frictions. These robot models are further used for testing the following presented nonlinear robot control methods: fuzzy control, variable-structure control and model-reference variable-structure control. In the fuzzy-logic control method seven fuzzy sets are defined for two input variables. Triangular input membership functions and the 7x7 fuzzy rule table are chosen. The fuzzy controller output value is calculated according to the centre of gravity principle. The same fuzzy control algorithm is used in all robot servo control loops with a proper scaling of the linguistic variables. To eliminate the chattering of the variable-structure control signal and to reduce energy consumption, sign function in the original variable-structure control law is replaced with the following functions: a continuous, saturation and exponential function, all of them with a very thin boundary layer. The same modifications are also made in the original model-reference variable-structure control method. In all presented control methods controller parameters are chosen according to the principle of maximal allowed tracking error and a minimum of energy consumption. These control methods are tested by computer simulations in C programming language in the case of moving the tool of the chosen robot arm. The simulation results proved similar efficiencies of all mentioned modified nonlinear robot control methods, although modified variable structure control algorithms are the most suitable because of their simplicity and lower number of controller parameters.Denavit-Hartenbergov algoritam i Lagrange-Eulerova metoda upotrijebljeni su za izradu realnog kinematičkog i dinamičkog modela troosnog rotacijskog ravninskog robota s električnim motorima i viskoznim, dinamičkim i statičkim trenjem. Ti su modeli robota kasnije korišteni za provjeru sljedećih predstavljenih nelinearnih postupaka upravljanja robotom: neizrazitog upravljanja, upravljanja s promjenjivom strukturom te upravljanja s referentnim modelom i promjenjivom strukturom. U metodi upravljanja s neizrazitom logikom definirano je sedam neizrazitih skupova za dvije ulazne varijable. Izabrane su trokutaste ulazne funkcije pripadnosti i tablica neizrazitih pravila veličine 7 x 7. Vrijednost izlaza neizrazitog regulatora izračunata je po principu težišta neizrazitog skupa. Isti neizraziti upravljački algoritam upotrijebljen je u svim petljama slijednog upravljanja robotom, uz odgovarajuće skaliranje jezičnih varijabli. Za uklanjanje trešnje iz upravljačkog signala s promjenjivom strukturom i zbog smanjenja potrošnje energije, funkcija predznaka je u prvobitnom zakonu upravljanja s promjenjivom strukturom zamijenjena sljedećim funkcijama: neprekidnom, funkcijom zasićenja i eksponencijalnom funkcijom, s vrlo tankim graničnim slojem u svima. Iste su promjene također napravljene i u originalnoj metodi upravljanja s referentnim modelom i promjenjivom strukturom. U svim su predstavljenim postupcima upravljanja parametri regulatora izabrani po principu najveće dozvoljene pogreške slijeđenja i najmanje potrošnje energije. Ove su metode upravljanja provjerene računalnim simulacijama u programskom jeziku C na primjeru kretanja alata izabrane robotske ruke. Rezultati simulacija dokazali su sličnu efikasnost svih spomenutih promijenjenih nelinearnih postupaka upravljanja robotom, iako su modificirani upravljački algoritmi s promjenjivom strukturom najprimjenjiviji zbog svoje jednostavnosti i manjeg broja parametara regulatora