Exposure level of ergonomic risk factors in grocery retail industries

Generally, grocery retail work requires manual material handling tasks that Involve Ergonomic Risk Factors (ERFs) such as posture, repetition and movements. The aim of this study was to examine the level of Ergonomic Risk Factors (ERFs) among material handlers in grocery retail industries. This study was conducted by using two different types of tools which were Workplace Ergonomic Risk Assessment (WERA) and Rapid Entire Body Assessment (REBA) as a direction observation method. For WERA method, results showed most of them experienced high exposure level for leg and contact stress while for REBA method, results showed most of them experienced medium exposure level for upper arm and trunk. From the research conducted, MSDs and ERFs do related as it showed that musculoskeletal disorders may arise if the workers ignored the safety in ergonomic risk factors. Hence, some ergonomic improvements are needed in order to prevent workers from developing MSDs

Language Design for Reactive Systems: On Modal Models, Time, and Object Orientation in Lingua Franca and SCCharts

Reactive systems play a crucial role in the embedded domain. They continuously interact with their environment, handle concurrent operations, and are commonly expected to provide deterministic behavior to enable application in safety-critical systems. In this context, language design is a key aspect, since carefully tailored language constructs can aid in addressing the challenges faced in this domain, as illustrated by the various concurrency models that prevent the known pitfalls of regular threads. Today, many languages exist in this domain and often provide unique characteristics that make them specifically fit for certain use cases. This thesis evolves around two distinctive languages: the actor-oriented polyglot coordination language Lingua Franca and the synchronous statecharts dialect SCCharts. While they take different approaches in providing reactive modeling capabilities, they share clear similarities in their semantics and complement each other in design principles. This thesis analyzes and compares key design aspects in the context of these two languages. For three particularly relevant concepts, it provides and evaluates lean and seamless language extensions that are carefully aligned with the fundamental principles of the underlying language. Specifically, Lingua Franca is extended toward coordinating modal behavior, while SCCharts receives a timed automaton notation with an efficient execution model using dynamic ticks and an extension toward the object-oriented modeling paradigm

Embedded System Design of Robot Control Architectures for Unmanned Agricultural Ground Vehicles

Engineering technology has matured to the extent where accompanying methods for unmanned field management is now becoming a technologically achievable and economically viable solution to agricultural tasks that have been traditionally performed by humans or human operated machines. Additionally, the rapidly increasing world population and the daunting burden it places on farmers in regards to the food production and crop yield demands, only makes such advancements in the agriculture industry all the more imperative. Consequently, the sector is beginning to observe a noticeable shift, where there exist a number of scalable infrastructural changes that are in the process of slowly being implemented onto the modular machinery design of agricultural equipment. This work is being pursued in effort to provide firmware descriptions and hardware architectures that integrate cutting edge technology onto the embedded control architectures of agricultural machinery designs to assist in achieving the end goal of complete and reliable unmanned agricultural automation. In this thesis, various types of autonomous control algorithms integrated with obstacle avoidance or guidance schemes, were implemented onto controller area network (CAN) based distributive real-time systems (DRTSs) in form of the two unmanned agricultural ground vehicles (UAGVs). Both vehicles are tailored to different applications in the agriculture domain as they both leverage state-of-the-art sensors and modules to attain the end objective of complete autonomy to allow for the automation of various types of agricultural related tasks. The further development of the embedded system design of these machines called for the developed firmware and hardware to be implemented onto both an event triggered and time triggered CAN bus control architecture as each robot employed its own separate embedded control scheme. For the first UAGV, a multiple GPS waypoint navigation scheme is derived, developed, and evaluated to yield a fully controllable GPS-driven vehicle. Additionally, obstacle detection and avoidance capabilities were also implemented onto the vehicle to serve as a safety layer for the robot control architecture, giving the ground vehicle the ability to reliability detect and navigate around any obstacles that may happen to be in the vicinity of the assigned path. The second UAGV was a smaller robot designed for field navigation applications. For this robot, a fully autonomous sensor based algorithm was proposed and implemented onto the machine. It is demonstrated that the utilization and implementation of laser, LIDAR, and IMU sensors onto a mobile robot platform allowed for the realization of a fully autonomous non-GPS sensor based algorithm to be employed for field navigation. The developed algorithm can serve as a viable solution for the application of microclimate sensing in a field. Advisors: A. John Boye and Santosh Pitl

Algorithmes et architectures pour la commande et le diagnostic de systèmes critiques de vol

Flight-Critical Systems such as Electromechanical Actuators driven by Engine Control Units (ECU) or Flight Control Units (FCU) are designed and developed regarding drastic safety requirements. In this study, an actuator control and monitoring ECU architecture based on analytic redundancy is proposed. In case of fault occurrences, material redundancies in avionic equipment allow certaincritical systems to reconfigure or to switch into a safe mode. However, material redundancies increase aircraft equipment size, weight and power (SWaP). Monitoring based on dynamical models is an interesting way to further enhance safetyand availability without increasing the number of redundant items. Model-base dfault detection and isolation (FDI) methods [58, 26, 47] such as observers and parity space are recalled in this study. The properties of differential flatness for nonlinear systems [80, 41, 73] and endogenous feedback linearisation are used with nonlinear diagnosis models. Linear and nonlinear observers are then compared with an application on hybrid stepper motor (HSM). A testing bench was specially designed to observe in real-time the behaviour of the diagnosis models when faults occur on the stator windings of a HSM.Les systèmes critiques de vol tels que les actionneurs électromécaniques ainsi que les calculateurs de commande moteur (ECU) et de vol (FCU),sont conçus en tenant compte des contraintes aéronautiques sévères de sureté defonctionnement. Dans le cadre de cette étude, une architecture calculateur pourla commande et la surveillance d’actionneurs moteur et de surfaces de vol est proposée et à fait l’objet d’un brevet [13]. Pour garantir ces mesure de sureté, les ECU et FCU présentent des redondances matérielles multiples, mais engendrent une augmentation de l’encombrement, du poids et de l’énergie consommée. Pour ces raisons, les redondances à base de modèles dynamiques, présentent un atout majeur pour les calculateurs car elles permettent dans certains cas de maintenir les exigences d’intégrité et de disponibilité tout en réduisant le nombre de capteurs ou d’actionneurs. Un rappel sur les méthodes de diagnostic par générateurs de résidus et estimateurs d’états [58, 26, 47] est effectué dans cette étude. Les propriétés de platitude différentielle et la linéarisation par difféomorphisme et bouclage endogène [80, 41, 73] permettent d’utiliser des modèles linéaires équivalents avec les générateurs de résidus. Un banc d’essai a été conçu afin de valider les performances des algorithmes de diagnostic