Measurement and Modeling of a Cargo Bicycle Tire for Vehicle Dynamics Simulation

In the field of inner-city cargo transportation, solutions such as electrified cargo trailers are increasingly being used. To provide an intelligent drivetrain control system that improves driving dynamics and enables safety, it is necessary to know the characteristics of the trailer system. This includes the behavior of the tires. Existing investigations of bicycle tires focus on camber-angle-dependent models. However, in most trailers, a rigid mounting of the tires without camber is used. For this reason, a bicycle tire model is created within the scope of this study using real measurement data that represent a 20 in tire with typical wheel loads and without camber. The measurements were collected with the mobile tire measurement laboratory of the Bern University of Applied Sciences on an asphalt test site under real conditions. Crosstalk occurring in the measurement hub during the data collection was successfully corrected using a matrix method. With help of the so-called Magic Formula, a tire model was created that can be used for driving dynamics simulations and controller design

Buchstaben der Welt – Welt der Buchstaben

In der Gestalt von Buchstaben und anderen Schriftzeichen manifestieren sich Denktraditionen und Schreibhorizonte: Indem Buchstaben Zeichen figurieren, machen sie implizit kulturelles Wissen lesbar. Der Unicode-Standard bietet heute die umfassendste Codierung in der Kultur der Menschheit; das Verhältnis von universeller Lesbarkeit und der phänomenalen Gestalt prinzipiell aller Schriftzeichen wird hier neu verhandelt. In Zeiten weltweiter Kommunikationstechnologien stellt sich auf der einen Seite die Frage nach kulturellen und phänomenalen Besonderheiten von „Buchstaben der Welt“ auch in vergleichender Hinsicht daher neu: Wie entstehen die Schriftzeichen, die wir schreiben, das heißt, was sind die technischen, semiotischen, linguistischen oder ästhetischen Bedingungen für ihre Form in verschiedenen Sprachsystemen? Auf der anderen Seite eröffnet sich eine „Welt der Buchstaben“ im Sinne einer Innenwelt, die phänomenologisch philosophisch analysiert werden kann. – Beiträge, die philosophische Denkräume und die Erscheinungsformen von Kultur als Buchstaben ausloten, bilden einen Schwer punkt des Bandes. Komparative Betrachtungen zu fernöstlichen Zeichen und Schreibweisen, wie in der japanischen Kalligraphie, erlauben einen erweiterten Blick auf die unterschiedlichen Ausformungen von Zeichen und hiermit verbundene Funktionen. Grundlegende Erörterungen zur Buchstabengestalt runden den Band ab: aus Sicht der Semiologie, der Linguistik und des Schriftgestalters

A Novel Resorbable Composite Material Containing Poly(ester-co-urethane) and Precipitated Calcium Carbonate Spherulites for Bone Augmentation—Development and Preclinical Pilot Trials

Polyurethanes have the potential to impart cell-relevant properties like excellent biocompatibility, high and interconnecting porosity and controlled degradability into biomaterials in a relatively simple way. In this context, a biodegradable composite material made of an isocyanate-terminated co-oligoester prepolymer and precipitated calcium carbonated spherulites (up to 60% w/w) was synthesized and investigated with regard to an application as bone substitute in dental and orthodontic application. After foaming the composite material, a predominantly interconnecting porous structure is obtained, which can be easily machined. The compressive strength of the foamed composites increases with raising calcium carbonate content and decreasing calcium carbonate particle size. When stored in an aqueous medium, there is a decrease in pressure stability of the composite, but this decrease is smaller the higher the proportion of the calcium carbonate component is. In vitro cytocompatibility studies of the foamed composites on MC3T3-E1 pre-osteoblasts revealed an excellent cytocompatibility. The in vitro degradation behaviour of foamed composite is characterised by a continuous loss of mass, which is slower with higher calcium carbonate contents. In a first pre-clinical pilot trial the foamed composite bone substitute material (fcm) was successfully evaluated in a model of vertical augmentation in an established animal model on the calvaria and on the lateral mandible of pigs

Algorithms and Methods for the Fault-Tolerant Design of an Automated Guided Vehicle

Researchers around the globe have contributed for many years to the research field of fault-tolerant control; the importance of this field is ever increasing as a consequence of the rising complexity of technical systems, the enlarging importance of electronics and software as well as the widening share of interconnected and cloud solutions. This field was supplemented in recent years by fault-tolerant design. Two main goals of fault-tolerant design can be distinguished. The first main goal is the improvement of the controllability and diagnosability of technical systems through intelligent design. The second goal is the enhancement of the fault-tolerance of technical systems by means of inherently fault-tolerant design characteristics. Inherently fault-tolerant design characteristics are, for instance, redundancy or over-actuation. This paper describes algorithms, methods and tools of fault-tolerant design and an application of the concept to an automated guided vehicle (AGV). This application took place on different levels ranging from conscious requirements management to redundant elements, which were consciously chosen, on the most concrete level of a technical system, i.e., the product geometry. The main scientific contribution of the paper is a methodical framework for fault-tolerant design, as well as certain algorithms and methods within this framework. The underlying motivation is to support engineers in design and control trough product development process transparency and appropriate algorithms and methods

A Fuzzy Virtual Actuator for Automated Guided Vehicles

In the last decades, virtual sensors have found increasing attention in the research community. Virtual sensors employ mathematical models and different sources of information such as actuator states or sensors, which are already existing in a system, in order to generate virtual measurements. Additionally, in recent years, the concept of virtual actuators has been proposed by leading researchers. Virtual actuators are parts of a fault-tolerant control strategy and aim to accommodate faults and to achieve a safe operation of a faulty plant. This paper describes a novel concept for a fuzzy virtual actuator applied to an automated guided vehicle (AGV). The application of fuzzy logic rules allows integrating expert knowledge or experimental data into the decision making of the virtual actuator. The AGV under consideration disposes of an innovative steering concept, which leads to considerable advantages in terms of maneuverability, but requires an elaborate control system. The application of the virtual actuator allows the accommodation of several possible faults, such as a slippery surface under one of the drive modules of the AGV

Resilient Design of Product Service Systems with Automated Guided Vehicles

Automated guided vehicles undertake complex transportation tasks, for instance, in production and storage systems. In recent years, an increased focus on sustainability has occurred as the effects of ongoing climate change have become more apparent. Engineers are searching intensively for ways to design technical systems that are not only environmentally sustainable, but are also resilient to the challenges of the changing climate and other environmental conditions. The production of automated guided vehicles requires considerable resources; therefore, a long operation time is desirable for overall sustainability. The performance of transportation tasks requires certain processes, such as control, path planning, coordination/synchronization, and maintenance and update processes—the latter are also very important for a long operation time. This article proposes understanding these processes as services and to explore product service systems with automated guided vehicles. Due to their complexity, the efficient and safe operation of such systems can be at risk because of several factors, such as component faults, external attacks and disturbances. For several years both resilient control and resilience engineering have been researched as possible remedies. An extension of these two concepts to the early stages of system development processes and including the system’s hardware is proposed in this article. This extension is referred to as resilient design. A primary purpose of resilient design is sustainability through extended usability and planned updates. The main intention of this article is to provide a comprehensive understanding of resilient design through application to product service systems with automated guided vehicles. The basis for this contribution is an extensive literature review and detailed system analyses on different levels. The main research results include novel application modes for product development methods. The explanation of the results is supported by means of an illustrative example based on a product service system with automated guided vehicles

Approaches for Modelling the Physical Behavior of Technical Systems on the Example of Wind Turbines

Models of technical systems are an essential means in design and product-development processes. A large share of technical systems, or at least subsystems, are directly or indirectly connected with the generation or transformation of energies. In design science, elaborated modelling approaches were developed for different levels of product concretization, for instance, requirement models and function models, which support innovation and new product-development processes, as well as for energy-generating or -transforming systems. However, on one product-concretization level, the abstract level that describes the physical behavior, research is less mature, and an overview of the approaches, their respective advantages, and the connection possibilities between them and other modelling forms is difficult to achieve. This paper proposes a novel discussion structure based on modelling perspectives and digital-engineering frameworks. In this structure, current approaches are described and illustrated on the basis of an example of a technical system, a wind turbine. The approaches were compared, and their specific advantages were elaborated. It is a central conclusion that all perspectives could contribute to holistic product modelling. Consequently, combination and integration possibilities were discussed as well. Another contribution is the derivation of future research directions in this field; these were derived both from the identification of “white spots” and the most promising modelling approaches

Health-Aware Model-Predictive Control of a Cooperative AGV-Based Production System

In the paper, a new scheduling strategy for assembly systems consisting of cooperating Automated Guided Vehicles (AGVs) based on their remaining operational time is developed. The operational time is associated with state of charge and state of health of the AGV battery. While the latter is defined as a possible number of repetitions of a set of given tasks, both are impossible to measure on-line directly with conventional sensors. Therefore, a novel state-of-charge estimator is proposed, which uses battery current and voltage sensor readings. In contrast to the approaches presented in the literature, a comprehensive analysis of its convergence is provided. Subsequently, a state-of-health predictor is developed. With the above measures, a new control strategy for cooperative AGVs is proposed. It is achieved by the allocation of alternative tasks among two cooperating robots referring to the state of the accomplished tasks from the previous stage of the assembly process. The proposed method allows a predictive control of assembly processes with several constraints, e.g., productivity of each assembly station, speed of the communication, or operation capability of the robots involved in the assembling process. The final part of the paper shows an experimental study exhibiting the performance of the proposed approach

AGENTES- Agent-based Engineering of Mechatronic Products

An efficient and effective engineering of mechatronic products requires support by information technology; a promising approach is the application of intelligent software agents. A current project at the Hochschule Ravensburg-Weingarten called "Agentes" is exploring this approach. This paper follows two aims. Firstly, it is intended to elucidate the application of software agents in engineering processes for mechatronic products. Secondly, it is intended to elaborate initial requirements and a framework for the application of software agents in such processes. This elaboration is based on a detailed analysis of an engineering process of a mobile robot