A Dual-Mode Model Predictive Control Algorithm Trajectory Tracking in Discrete-Time Nonlinear Dynamic Systems

In this paper, a dual-mode model predictive/linear control method is presented, which extends the concept of dual-mode model predictive control (MPC) to trajectory tracking control of nonlinear dynamic systems described by discrete-time state-space models. The dual-mode controller comprises of a time-varying linear control law, implemented when the states lie within a sufficiently small neighborhood of the reference trajectory, and a model predictive control strategy driving the system toward that neighborhood. The boundary of this neighborhood is characterized so as to ensure stability of the closed-loop system and terminate the optimization procedure in a finite number of iterations, without jeopardizing the stability of the closed-loop system. The developed controller is applied to the central air handling unit (AHU) of a two-zone variable air volume (VAV) heating, ventilation, and air conditioning (HVAC) system

Optimal Constrained Planning for Complex Mechatronic Systems

This thesis focuses on the challenging problem of the optimal planning for mechatronic systems. The goal is to find strategies which maximize or minimize some cost criteria defined over a given constrained problem. The planning for mobile or industrial robots is a general framework under which several different open research issues can be found. Motion planning, in fact, involves the solution of a variety of optimality problems which range from the optimal path design to the optimal trajectory planning. Since, obviously, this is a very wide research field the scope of our analysis has been limited to three main contributions which represents the novelties proposed in this thesis. Initially, the optimal path generation problem is solved in the case of planar paths for mobile robots by using a new and powerful planning primitive recently proposed in the literature. Subsequently, the optimal path tracking problem is handled by a new control scheme able to online optimal scale any designed trajectory, which can be phisically unfeasible for the controlled system, in order to fulfill given kinematic and/or dynamic constraints. Finally, the problem of the generation of optimal controls for the minimum-time state transitions of nonlinear systems is presented and an innovative differential method is devised.La tesi tratta il problema della pianificazione ottima vincolata per sistemi meccatronici. In generale, l'obiettivo è la determinazione di strategie che minimizzino o massimizzino funzionali di costo definiti su dati problemi vincolati. Il termine di pianificazione ottima riferito a dispositivi robotici mobili o industriali individua una vasta area di ricerca all'interno della quale numerosi problemi di ottimizzazioni sono ancora indagati. La pianificazione di moto, infatti, richiede la risoluzione di una ampia varietà di problemi di ottimizzazione vincolata che spazia dalla ottima pianificazione di percorso alla pianificazione di traiettoria. Nella presente tesi, l'obiettivo di ricerca è stato limitato a tre importanti contributi innovativi. Inizialmente viene affrontato il problema della pianificazione di percorsi planari ottimi per dispositivi mobili mediante l'uso di una nuova ed estremamente versatile primitiva di pianificazione proposta in letteratura. Successivamente si affronta il problema dell'inseguimento di percorso. E' proposta una nuova struttura di controllo in grado di scalare in linea qualsiasi traiettoria pianificata, che potrebbe essere fisicamente irrealizzabile, in modo tale che i vincoli cinematici e dinamici che il sistema controllato impone siano soddisfatti. Infine si analizza il problema della generazione ottima di set-point per transizioni dello stato di generici sistemi nonlineari ed, in particolare, un innovativo metodo puramente differenziale per il controllo a tempo minimo è descritto

Smooth Trajectory Generation for Machine Tools and Industrial Robots

This thesis presents accurate and time-optimal smooth reference trajectory generation techniques for manufacturing equipment such as high-speed machine tools (MT) and industrial robots (IR). Typical machining tool-paths for MTs and IRs are defined as a series of discrete linear moves. Although Point-to-Point (P2P) feed motion can be generated by interpolating each linear segment with high-order velocity profiles, the continuous and accurate transition between consecutive segments is necessary to realize a non-stop contouring motion for efficient manufacturing. To generate continuous feed motion along sharp cornered tool-paths, most numerical control (NC) systems blend (smooth) corners locally using various curves and splines. The feed (speed) is reduced around the blend sections so that the motion system’s kinematic limits are respected. This thesis proposes 2 novel techniques to enable modern MT and IR to generate non-stop rapid motion along discrete tool-paths. Firstly, a Kinematic Corner Smoothing (KCS) technique has been proposed to generate time-optimal (minimum time) motion trajectories in a real-time within axis kinematic limits. A novel real-time interpolation technique based on Finite Impulse Response (FIR) filtering has also been proposed to suppress residual vibrations for high positioning accuracy of machine tools and motion systems as well. These two techniques are tailored for Cartesian structured motion systems such as 2-3 axis machine tools. Finally, a decoupled FIR filtering technique has been developed to synchronously interpolate tool position and orientation for accurate motion generation for 5-axis MTs and IRs. These techniques are computationally lightweight and suitable for real-time implementation on modern NC systems. Simulation and experimental validation on Cartesian and 5-axis machine tools are presented to validate the effectiveness of the developed algorithms to interpolate along with discrete commands for high-speed and high-accuracy motion

Дві декомпозиції в системах векторного керування електричними машинами змінного струму

Дисертаційна робота складається зі вступу, 6 розділів, висновків, списку використаних джерел з 52 найменувань і 16 додатків. Повний обсяг дисертації становить 248 сторінок і 29 рисунків. Мета роботи – підвищення динамічних показників та енергоефективності керування в ЕМС з векторно-керованими електричними двигунами за рахунок розробки узагальнених нелінійних методів керування з вільно формованими показниками якості керування. В роботі здійснено аналіз існуючих методів керування класом нелінійних об’єктів з електромеханічним перетворенням енергії, які піддаються перетворенню Блондель-Парка, і визначено, що на даний час узагальнених методів керування всіма електричними машинами даного класу немає або вони є дуже складними. Як альтернатива запропоновано узагальнений метод синтезу векторного керування на основі полеорієнтованого перетворення координат з декомпозицією електромеханічної системи на електромеханічну електромагнітну підсистеми та механічну-електричну підсистеми. Для прикладу та доведення асимптотичної стійкості і розв’язки процесів керування в цих підсистемах виконано синтез алгоритмів керування механічними координатами наступних двигунів: двигун постійного струму з незалежним збудженням, явнополюсний синхронний двигун з постійними магнітами, асинхронний двигун з короткозамкненим ротором при прямій та непрямій орієнтації за полем ротора.The dissertation consists of an introduction, 6 sections, conclusions, a list of sources used with 52 names and 16 appendices. The full volume of the dissertation is 248 pages and 29 figures. The purpose of the work is to increase of dynamic performance and energy efficiency of control in EMS with vector-controlled electric motors due to development of the generalized nonlinear control methods with freely formed indicators of control performance. The paper analyzes the existing methods of control of a class of nonlinear objects with electromechanical energy conversion that are subject to the transformation of Blondel-Park, and determines that currently there are no generalized methods of control of all electric machines of this class or they are very complex. As an alternative, a generalized method of synthesis of vector control based on field-oriented transformation of coordinates with decomposition of electromechanical system into electromechanical-electromagnetic subsystems and mechanical-electric subsystems is proposed. To illustrate and prove the asymptotic stability and solution of control processes in these subsystems, a synthesis of control algorithms for the mechanical coordinates of the following motors was performed: DC motor with independent excitation, interior permanent magnets synchronous motor, induction motor with shortcircuit rotor

Kinematics and Robot Design II (KaRD2019) and III (KaRD2020)

This volume collects papers published in two Special Issues “Kinematics and Robot Design II, KaRD2019” (https://www.mdpi.com/journal/robotics/special_issues/KRD2019) and “Kinematics and Robot Design III, KaRD2020” (https://www.mdpi.com/journal/robotics/special_issues/KaRD2020), which are the second and third issues of the KaRD Special Issue series hosted by the open access journal robotics.The KaRD series is an open environment where researchers present their works and discuss all topics focused on the many aspects that involve kinematics in the design of robotic/automatic systems. It aims at being an established reference for researchers in the field as other serial international conferences/publications are. Even though the KaRD series publishes one Special Issue per year, all the received papers are peer-reviewed as soon as they are submitted and, if accepted, they are immediately published in MDPI Robotics. Kinematics is so intimately related to the design of robotic/automatic systems that the admitted topics of the KaRD series practically cover all the subjects normally present in well-established international conferences on “mechanisms and robotics”.KaRD2019 together with KaRD2020 received 22 papers and, after the peer-review process, accepted only 17 papers. The accepted papers cover problems related to theoretical/computational kinematics, to biomedical engineering and to other design/applicative aspects

Nonlinear filters for the generation of smooth trajectories

A nonlinear variable structure (VS) system is presented, suitable for smooth trajectory generation in motion control system. Joined to a rough reference trajectory generator (step, ramp, etc.) it provides smooth output signals according to user-selectable bounds on trajectory derivatives. The bounds on output derivatives can be changed during system operation without impairing system stability. Moreover, minimum time response with guaranteed no overshoot is ensured both in the continuous and discrete-time implementations. The main contribution of the paper lies in the discrete-time version of the trajectory generator. The performance of the proposed nonlinear filters is tested through simulation experiments. Simulation results concerning the use of the discrete filter in a position tracking control system are also presented