On periodically pendulum-diven systems for underactuated locomotion: a viscoelastic jointed model

This paper investigates the locomotion principles and nonlinear dynamics of the periodically pendulum-driven (PD) systems using the case of a 2-DOF viscoelastic jointed model. As a mechanical system with underactuation degree one, the proposed system has strongly coupled nonlinearities and can be utilized as a potential benchmark for studying complicated PD systems. By mathematical modeling and non-dimensionalization of the physical system, an insight is obtained to the global system dynamics. The proposed 2-DOF viscoelastic jointed model establishes a commendable interconnection between the system dynamics and the periodically actuated force. Subsequently, the periodic locomotion principles of the actuated subsystem are elaborately studied and synthesized with the characteristic of viscoelastic element. Then the analysis of qualitative changes is conducted respectively under the varying excitation amplitude and frequency. Simulation results validate the efficiency and performance of the proposed system comparing with the conventional system

Jūriniame intermodaliniame terminale naudojamų išmaniųjų krovos technologijų kūrimas ir tyrimas

Disertacijoje sumanaus krantinės krano nauja samprata yra tiesiogiai siejama su išmanaus konteinerio ir autonominio konteinerių vežėjo koncepcijų diegimu uostuose. Autonominio uosto vizijoje, artėjant krantinės krano griebtuvui prie konteinerio, radijo dažnio atpažinimo (RDA) technologija užkoduota informacija apie krovinio atsparumą perkrovai privalės būti tie-siogiai perduodama kranto valdymo sistemai. Apdoroti duomenys leis generuoti kiekvienam konteineriui individualizuotus sparčius ir saugius perkrovos režimus, atsižvelgiant į vėjo ir laivo sukeltus svyravimus ir t. t. Didžiųjų krantinės kranų griebtuvo įvairiakrypčius svyravimus slopinančios sumaniosios valdymo sistemos sukūrimas tampa vienu iš pagrindinių disertacijos uždavinių. Toks intelektinio transporto uždavinys yra sprendžiamas sukuriant krantinės krano laboratorinį prototipą ir jam pritaikytus matematinius ir valdymo sistemą imituojančius modelius, praktikoje taikant profilinį valdymą, realizuojamą proporciniu (P), integruojančiu (I) ir diferencijuojančiu (D) valdikliu (PID). Pabrėžtina, kad taikant PID valdiklį sistemose, kuriose pagrindinis transportuojamas objektas – konteineris kuris kabo ant ilgų lynų, gaunamos nemažos paklaidos. Disertacijoje sukurta virtuali sistemos skaitinio modeliavimo aplinka, kurios rezultatai patikrinti eksperimentu, tam panaudojant suprojektuotą ir pagamintą realaus krantinės krano laboratorinį prototipą. Disertaciją sudaro įvadas, trys skyriai, bendrosios išvados, naudotos li-teratūros ir autoriaus publikacijų sąrašai bei santrauka anglų kalba. Įvade aptariama tiriamoji problema, darbo aktualumas, aprašomas tyrimų objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų praktinė reikšmė, ginamieji teiginiai. Pirmasis skyrius skirtas literatūros apžvalgai. Aptarti žinomi kontei-nerio perkrovos laivas–krantinė matematiniai modeliai ir jais grindžiami sistemos valdymo algoritmai. Antrajame skyriuje aprašomi krantinės krano kėlimo mechanizmo matematiniai modeliai bei pateikiama diferencinių lygčių sistema skirta krantinės krano kėlimo mechanizmo ir griebtuvo su kroviniu sukeliamų svyravimų skaitiniam modeliavimui ir įtakos krovai vertinimui. Trečiajame skyriuje, apibendrinus virtualaus modeliavimo išvadas, projektuojamas ir sukuriamas krantinės krano laboratorinis prototipas valdymo algoritmų eksperimentams tyrimams atlikti. Taip pat aprašomas sukurtas valdymo algoritmas su svyravimų kompensavimo grandimi. Disertacija baigiama tyrimą apibendrinančiomis išvadomis. Disertacijos tema paskelbta 11 straipsnių: vienas – straipsnių rinkinyje, įtrauktame į Thomson ISI sąrašą, du – tarptautiniuose recenzuojamuose mokslo leidiniuose, 8 Lietuvoje bei kitose šalyse vykusių konferencijų leidiniuose

Advanced Discrete-Time Control Methods for Industrial Applications

This thesis focuses on developing advanced control methods for two industrial systems in discrete-time aiming to enhance their performance in delivering the control objectives as well as considering the practical aspects. The first part addresses wind power dispatch into the electricity network using a battery energy storage system (BESS). To manage the amount of energy sold to the electricity market, a novel control scheme is developed based on discrete-time model predictive control (MPC) to ensure the optimal operation of the BESS in the presence of practical constraints. The control scheme follows a decision policy to sell more energy at peak demand times and store it at off-peaks in compliance with the Australian National Electricity Market rules. The performance of the control system is assessed under different scenarios using actual wind farm and electricity price data in simulation environment. The second part considers the control of overhead crane systems for automatic operation. To achieve high-speed load transportation with high-precision and minimum load swings, a new modeling approach is developed based on independent joint control strategy which considers actuators as the main plant. The nonlinearities of overhead crane dynamics are treated as disturbances acting on each actuator. The resulting model enables us to estimate the unknown parameters of the system including coulomb friction constants. A novel load swing control is also designed based on passivity-based control to suppress load swings. Two discrete-time controllers are then developed based on MPC and state feedback control to track reference trajectories along with a feedforward control to compensate for disturbances using computed torque control and a novel disturbance observer. The practical results on an experimental overhead crane setup demonstrate the high performance of the designed control systems.Comment: PhD Thesis, 230 page

Bio-inspired robotic control in underactuation: principles for energy efficacy, dynamic compliance interactions and adaptability.

Biological systems achieve energy efficient and adaptive behaviours through extensive autologous and exogenous compliant interactions. Active dynamic compliances are created and enhanced from musculoskeletal system (joint-space) to external environment (task-space) amongst the underactuated motions. Underactuated systems with viscoelastic property are similar to these biological systems, in that their self-organisation and overall tasks must be achieved by coordinating the subsystems and dynamically interacting with the environment. One important question to raise is: How can we design control systems to achieve efficient locomotion, while adapt to dynamic conditions as the living systems do? In this thesis, a trajectory planning algorithm is developed for underactuated microrobotic systems with bio-inspired self-propulsion and viscoelastic property to achieve synchronized motion in an energy efficient, adaptive and analysable manner. The geometry of the state space of the systems is explicitly utilized, such that a synchronization of the generalized coordinates is achieved in terms of geometric relations along the desired motion trajectory. As a result, the internal dynamics complexity is sufficiently reduced, the dynamic couplings are explicitly characterised, and then the underactuated dynamics are projected onto a hyper-manifold. Following such a reduction and characterization, we arrive at mappings of system compliance and integrable second-order dynamics with the passive degrees of freedom. As such, the issue of trajectory planning is converted into convenient nonlinear geometric analysis and optimal trajectory parameterization. Solutions of the reduced dynamics and the geometric relations can be obtained through an optimal motion trajectory generator. Theoretical background of the proposed approach is presented with rigorous analysis and developed in detail for a particular example. Experimental studies are conducted to verify the effectiveness of the proposed method. Towards compliance interactions with the environment, accurate modelling or prediction of nonlinear friction forces is a nontrivial whilst challenging task. Frictional instabilities are typically required to be eliminated or compensated through efficiently designed controllers. In this work, a prediction and analysis framework is designed for the self-propelled vibro-driven system, whose locomotion greatly relies on the dynamic interactions with the nonlinear frictions. This thesis proposes a combined physics-based and analytical-based approach, in a manner that non-reversible characteristic for static friction, presliding as well as pure sliding regimes are revealed, and the frictional limit boundaries are identified. Nonlinear dynamic analysis and simulation results demonstrate good captions of experimentally observed frictional characteristics, quenching of friction-induced vibrations and satisfaction of energy requirements. The thesis also performs elaborative studies on trajectory tracking. Control schemes are designed and extended for a class of underactuated systems with concrete considerations on uncertainties and disturbances. They include a collocated partial feedback control scheme, and an adaptive variable structure control scheme with an elaborately designed auxiliary control variable. Generically, adaptive control schemes using neural networks are designed to ensure trajectory tracking. Theoretical background of these methods is presented with rigorous analysis and developed in detail for particular examples. The schemes promote the utilization of linear filters in the control input to improve the system robustness. Asymptotic stability and convergence of time-varying reference trajectories for the system dynamics are shown by means of Lyapunov synthesis