Rejection of yaw disturbance in a two-wheeled wheelchair system

In this paper, a virtual wheelchair (WC) model is developed within Visual Nastran (VN) software environment where the model is further linked with Matlab/Simulink for control purposes. The goal is to have stable two-wheeled WC by transforming the two front wheels (caster) to the upright position. Theoretically, when the two big wheels are fed by the same torque, the WC system will only move in one (x-) direction (with a small forward and backward movement before settlement is achieved). On the other hand, WC in VN produces action-reaction forces in terms of friction between the wheels and the defined ground that lead to small degree of rotation with respect to vertical z- axis, (yaw disturbance). Fuzzy logic control is designed in order to eliminate this unwanted rotation of the wheels during lifting and stabilizing phase. Results show that the unwanted rotation of the wheels is successfully reduced

Development And Human Performance Evaluation Of Control Modes Of An Exo-Skeletal Assistive Robotic Arm (esara)

This research was conducted to assist with functional tasks for a targeted group of individuals with spinal cord injury (SCI); with C5 to C7 level of injury relating to upper extremity movement. The specific population was selected as the existing technology was either too expensive, too bulky or was unable to address their needs in regards to upper extremity mobility. In addition, no platforms allowed multimodal control options for customization or provided a methodology for this crucial evaluation. The motivation of this research was to provide a methodology for selecting the appropriate control of an assistive device based on the range of basic human movements that were possible by the population under consideration (button pushing, lever sliding, and speech). The main idea was to create an evaluation methodology based on a user platform with multiple modes of control. The controls were developed such that they would allow operation of the device with respect to the capabilities of SCI participants. Engineering advancements have taken assistive robotics to new dimensions. Technologies such as wheelchair robotics and myo-electronically controlled systems have opened up a wide range of new applications to assist people with physical disabilities. Similarly exo-skeletal limbs and body suits have provided new foundations from which technologies can aid function. Unfortunately, these devices have issues of usability, weight, and discomfort with donning. The Smart Assistive Reacher Arm (SARA) system, developed in this research, is a voice-activated, lightweight, mobile device that can be used when needed. SARA was built to help overcome daily reach challenges faced by individuals with limited arm and hand movement capability, such as people with cervical level 5-6 (C5-6) SCI. The functional reacher arm with voice control can be beneficial for this population. Comparison study with healthy participants and an SCI participant shows that, when using SARA, a person with SCI can perform simple reach and grasp tasks independently, without someone else\u27s help. This suggests that the interface is intuitive and can be easily used to a high-level of proficiency by a SCI individual. Using SARA, an Exo-Skeletal Assistive Robotic Arm (eSARA) was designed and built. eSARA platform had multiple modes of control namely, voice (ballistic mode with no extremity movement), button (ballistic mode with minor extremity movement) and slider (continuous mode with major extremity movement). eSARA was able to extend a total of 7 inches from its original position. The platform also provided lift assist for users that can potentially enable them to lift up to 20lbs.The purpose of eSARA was to build a platform that could help design a methodology to select the modality for a specific level of SCI injury or capability. The eSARA platform\u27s Human Machine Interface (HMI) was based on two experiments `Fine movement experiment\u27 and `Gross movement experiment\u27. These experiments tested the reaching, grasping and lifting ability of the platform. Two groups of healthy young adults were selected to perform the experiment. The first group, 12 healthy participants, had no movement restrictions. The second group, 6 Occupational Therapy students, that could mimic restrictions similar to those of a level 5-6 SCI individual. The experiment was also conducted by an SCI individual. The results of the 2 groups from both the experiments were compared with the results of the SCI participant. It was found that the SCI participant\u27s time performance to finish the tasks was comparable to the average of the healthy participants. It was concluded that the developed methodology and platforms could be used to evaluate the control modes needed in order to customize the system to the capabilities of SCI individual. . These platforms can be tested for a broader range of participants including participants with arthritis, recovering from paralysis and seniors with movement issues

Elektrikli tekerlekli sandalyenin ayrık-zaman optimal kontrolü

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Anahtar kelimeler: Elektrikli Tekerlekli Sandalye (ETS), Açısal Hız, Bozucu, Gözlemci, Model Öngörülü Kontrol (MÖK), Bozucu Gözleyici Destekli Model Öngörülü Kontrol (BGDMÖK) Elektrikli tekerlekli sandalye (ETS) engelli kişilerce kullanılan hareketlilik yardımcısı cihazlardır. Bağımsız hareket etmesi gereken veya el ile tekerlekli sandalye kullanamayan insanlar için ETS yararlıdır ve gereklidir. Tekerlekli sandalyede hız kontrol edilecek en önemli unsurdur. ETS sürüşü sırasında ortaya çıkan belirsiz çevre etkileri veya bozucuları ETS hız kontrolünün temel problemidir. Bu tez çalışmasında, çok giriş çok çıkışlı ve kublajlı olan ETS'nin sağ tekerlek ve sol tekerlek açısal hızlarını bir birinden bağımsız olarak kontrol etmek ve bozucu etkisini ortadan kaldırmak için kontrol yöntemleri önerilmiş ve tasarımları yapılmıştır. ETS'nin enerji denklemleri yazılır ve bu denklemlerden ayrık-zaman durum denklemleri doğrudan elde edilerek ETS modellenir. Durum uzay modeli kullanılarak Luenberger gözleyici sağ tekerlek ve sol tekerlek DC motor akımlarını ve hızlarını kestirmek için tasarlanır. ETS’nin hız kontrolönü yapmak üzere ayrık-zaman optimal Model Öngörülü Kontrol (MÖK) ve bozucu etkisini ortadan kaldırmak için Bozucu Gözleyici Destekli Model Öngörülü Kontrol (BGDMÖK) önerileri yapılır ve ETS nin ayrık-zaman durum uzay modeli kullanılarak tasarım yapılır. ETS’nin elde edilen ayrık zaman durum uzay model doğrulaması, ETS’nin sağ ve sol teker hızlarının bozucu etkiler altında bağımsız kontrölü için önerilen MÖK ve BGDMÖK yöntemlerinin performans değerlendirmeleri ve karşılaştırmaları benzetim çalışmaları ile verilmektedir. DISCRETE TIME OPTIMAL CONTROL OF ELECTRIC POWERED WHEELCHAIR (EPW)Keywords: Electric Powered Wheelchair (EPW), angular velocity, disturbance, observer, Model Predictive Control (MPC), Disturbance Observer Support to Model Predictive Control (DOSMPC) Electric powered wheelchair (EPW) is the mobility assistive device used by disabled persons. EPW is useful and necessary for people who are not able to use a manual wheelchair or for people who must move independently. The velocity of wheelchair is the important aspect to be controlled. The uncertain environmental effects or disturbances occuring during the EPW driving is the major problem of EPW velocity control. In this thesis, control methods have been proposed and implemented to eliminate the disturbance effect and to independently control the right and left wheel angular velocities of EPW that is a coupled and multi-input multi-output system. The energy equations are written and EPW is modeled by obtaining the discrete time state equations from the energy equations directly. By using state space model, the Luenberger observer is designed to estimate DC motor currents and velocities of right and left wheels. Discrete time optimal Model Predictive Control (MPC) for velocity control of EPW and Disturbance Observer Supported Model Predictive Control (DOSMPC) for eliminating disturbance effect are proposed and state space model of EPW is used in design. The discrete time state space model verification of the EPW is done by providing simulation results giving performance evaluation and comparison of MPC and DOSMPC methods proposed for independent velocity control of right and left wheels of ETS in the presence disturbance effect

외란 관측기의 이론적 해석 : 안정성 및 성능

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 8. 심형보.This dissertation provides the stability and performance analysis of the disturbance observer and proposes several design methods for guaranteeing the robust stability and for enhancing the disturbance rejection performance. Compared to many success stories in industry, theoretic analysis on the disturbance observer itself has attracted relatively little attention. In order to enlarge the horizon of its applications, we provide some rigorous analysis both in the frequency and time domain. In the frequency domain, we focus on two main issues: disturbance rejection performance and robust stability. In spite of its powerful ability for disturbance rejection, the conventional disturbance observer rejects the disturbance approximately rather than asymptotically. To enhance the disturbance rejection performance, based on the well-known internal model principle, we propose a design method to embed an internal model into the disturbance observer structure for achieving the asymptotic disturbance rejection and derive a condition for robust stability. Thus, the proposed disturbance observer can reject not only approximately the unmodeled disturbances but also asymptotically the disturbances of sinusoidal or polynomial-in-time type. In addition, a constructive design procedure to satisfy the proposed stability condition is presented. The other issue is to design of the disturbance observer based control system for guaranteeing robust stability under plant uncertainties. We study the robust stability for the case that the relative degree of the plant is not exactly known and so it happens to be different from that of nominal model. Based on the above results, we propose a universal design method for the disturbance observer when the relative degree of the plant is less than or equal to 4. Moreover, from the observation about the role of each block, we generalize the design of disturbance observer and propose a reduced order type-k disturbance observer to improve the disturbance rejection performance and to reduce the design complexity simultaneously. As a counterpart of the frequency domain analysis, we analyze the disturbance observer in the state space for the purpose of extending the horizon of the disturbance observer applications and obtaining the deeper understanding of the role of each block. Based on the singular perturbation theory, it reveals not only well-known properties but also interesting facts such as the peaking in the transient response. Moreover, we investigate robust stability of the disturbance observer based control systems with and without unmodeled dynamics and derive an explicit relation between the nominal performance recovery and the time constant of Q-filter. Since the classical linear disturbance observer does not ensure the recovery of transient response, a nonlinear disturbance observer, in which all the benefits of the classical one are still preserved, is presented for guaranteeing the recovery of transient as well as steady-state response.Abstract List of Figures Symbols and Acronyms 1. Introduction 1.1 Motivation 1.2 Contributions and Outline of the Dissertation 2. Robust Stability for Closed-loop System with Disturbance Observer 2.1 Structure of Disturbance Observer 2.2 Robust Stability Condition for Closed-loop System with Disturbance Observer 2.3 Illustrative Example 3. Embedding Internal Model in Disturbance Observer with Robust Stability 3.1 Design Method for Embedding Internal Model of Disturbance 3.2 Design of Q-filter for Guranteeing Robust Stability 3.2.1 Robust Stability Condition of Closed-loop System 3.2.2 Selecting a_i's for Robust Stability 3.3 Illustrative Example 3.4 Discussions on Robustness 3.4.1 Pros and Cons of Proposed Design Procedure 3.4.2 Bode Diagram Approach 4. Disturbance Observer with Unknown Relative Degree of the Plant 4.1 Robust Stability 4.2 A Guideline for Selecting Q and P_n 4.2.1 A Universal Robust Controller 4.3 Technical Proofs 4.4 Illustrative Examples 5. Reduced Order Type-k Disturbance Observer under Generalized Q-filter 5.1 Concept of Disturbance Observer with Generalized Q-filter Structure 5.2 Robust Stability 5.3 Reduced Order Type-k Disturbance Observer 5.4 Illustrative Examples 6. State Space Analysis of Disturbance Observer 6.1 State Space Realization of Disturbance Observer 6.2 Analysis of Disturbance Observer based on Singular Perturbation Theory 6.3 Discussion on Disturbance Observer Approach 6.3.1 Relation of Robust Stability Condition between State Space and Frequency Domain Approach 6.3.2 Effect of Zero Dynamics 6.3.3 Stability of Nominal Closed-loop System 6.3.4 Infinite Gain Property with p-dynamics 6.3.5 Peaking in Fast Transient 6.4 Nominal Performance Recovery with respect to Time Constant of Q-filter 7. Nominal Performance Recovery and Stability Analysis of Disturbance Observer under Unmodeled Dynamics 7.1 Problem Formulation 7.2 Stability and Performance Analysis based on Singular Perturbation Theory 7.2.1 Nominal Performance Recovery 7.2.2 Multi-time-scale Singular Perturbation Analysis 7.3 Nominal Performance Recovery by Disturbance Observer under Unmodeled Dynamics 8. Extensions of Disturbance Observer for Guaranteeing Robust Transient Performance 8.1 Extensions to MIMO Nonlinear Systems 8.1.1 SISO Nonlinear Disturbance Observer with Nonlinear Nominal Model 8.1.2 MIMO Nonlinear Disturbance Observer with Linear Nominal Model 9. Conclusions Appendix Bibliography 국문초록Docto

Analyse biomécanique et électromyographique des éléments d'anticipation de l'initiation de déplacement en fauteuil roulant manuel

People with Disabled Mobility (PDM) often suffer from limitation during locomotion. Several tools are at their disposal to help and assist them in their displacement, specifically the electric or the Manual Wheelchair (MW). This thesis works focuses on the Human-MW-Interaction (H-MW-I) subject to determine elements predictors of forthcoming displacement with a view of aid to locomotion. Understanding (H-MW-I) is a current challenge to improve the displacement and optimize the performance as well as comfort, by minimizing fatigue and injury risk. In order to enhance understanding and even improving the (H-MW-I), a set of studies focusing on Biomechanics and electromyographic analysis of anticipation elements of the Manual Wheelchair Initiation Displacement (MW-ID) was performed during the thesis works. This set of studies focuses on i) Anticipatory Muscular Activities (AMA) in the sitting position to question the predictability of the movements in relation to its prior parameters; ii) evolution of muscular patterns and pressures on the seat when MW-ID to question the adaptability or specificity of the initial parameters during various displacements using MW in healthy subjects ; iii) evolution of muscular patterns and pressures on the seat when MW-ID in spinal cord injury subjects and; iv) multivariate analysis of the MW-ID parameters. The CNS presents an important capacity of adaptability to the forthcoming movement by adjusting motor commands to the global physiological condition of the subject. This adaptability has led to significant percentages prediction and it can be saved through macroscopic elements to envisage help systems to displacement for PDM.Les Personnes à Mobilité Réduite (PMR) souffrent souvent de limitation au cours de la locomotion. Plusieurs outils sont à leurs dispositions pour les aider et les assister dans leur déplacement, plus particulièrement le Fauteuil Roulant Manuel (FRM) ou électrique. Ces travaux de thèse se focalisent sur les interactions entre le sujet et le FRM afin de déterminer des éléments prédictifs du déplacement à venir dans l’optique d’une aide à la locomotion. Comprendre l'Interaction Homme-FRM (IHF) est un enjeu actuel afin d'améliorer le déplacement et d’optimiser la performance ainsi que le confort, en minimisant la fatigue et les risques des blessures. Pour contribuer à mieux comprendre voire améliorer cette IHF, un ensemble d'études centrées sur une analyse biomécanique et électromyographique des éléments d'anticipation de l'Initiation du Déplacement en FRM (ID-FRM) a été réalisé au cours de ces travaux de thèse. Cet ensemble d’études porte sur i) les Activités Musculaires Anticipatoires (AMA) en position assise pour interroger la prédictibilité des mouvements au regard de ses paramètres préalables ; ii) l’évolution des patterns musculaires et des pressions sur l'assise lors de l'ID-FRM, pour interroger l’adaptabilité ou la spécificité des paramètres initiaux lors de différents déplacements en FRM chez des sujets valides. ; iii) l’évolutions des patterns musculaires et des pressions sur l'assise lors de l'ID-FRM chez des sujets blessés médullaires et ; iv) l’analyse multi-variée des paramètres de l'ID-FRM. Le SNC présente des capacités d'adaptabilité importantes au mouvement à venir en ajustant les commandes motrices aux conditions physiologiques globales du sujet. Cette adaptabilité a conduit à des pourcentages importants de prédiction et elle peut être enregistrée au travers d'éléments macroscopiques permettant d'envisager des systèmes d'aide au déplacement, notamment pour les PMR