A Linear Parameter-Varying Control Method for Inline Wheel Systems

The design of the bicycle and other single-track systems are continually evolving and have become a key tool for people and goods transportation worldwide [1],[2]. The form factor, carrying capacity, maneuverability, and cost of single-track vehicles makes them advantageous in a variety of circumstances and justifies their use case in the 21st Century [2] [3],[4]. As autonomous double track vehicles arrive on public roads, it is natural that single-track autonomous systems will be developed as well; however, the unstable and non-minimum phase dynamics of single-track vehicles make their control have an additional layer of complexity compared to double track vehicles. Although many researchers have provided commentary on the stability and tracking of a riderless bicycle, relatively few bodies of work have validated their analysis through experimental testing. This work successfully demonstrates that, through gain scheduling, a PID-type controller can balance a riderless single-track vehicle by using a linear actuator to implement front-fork steering control. This control system is novel in the way in which the front fork is actuated. The manual PID tuning process outlined in this body of work is also unique, as well as the specifics of the control law (although PID controllers have been used by other authors). The works of other authors on this topic is briefly summarized and a second-order dynamics system model is derived. Then controller analysis is simulated and then validated experimentally. Suggestions are also made on next steps that can be taken to build upon the work outlined in this thesis.MSEElectrical Engineering, College of Engineering & Computer ScienceUniversity of Michigan-Dearbornhttp://deepblue.lib.umich.edu/bitstream/2027.42/169157/1/Ronald Smith Final Thesis.pd

Bicycles, Motorcycles and Models

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Path Following and Stabilization of an Autonomous Bicycle

In this thesis we investigate the problem of designing a control system for a modern bicycle so that the bicycle is stable and follows a path. We propose a multi-loop control architecture, where each loop is systematically designed using linear control techniques. The proposed strategy guarantees that the bicycle asymptotically converges to paths of constant curvature. A key advantage of our approach is that by using linear techniques analysis and controller design are relatively simple. We base our control design on the nonlinear (corrected) Whipple model, which has been previously verified for correctness and experimentally validated. The equations of motion for the nonlinear model are very complicated, and would take many pages to explicitly state. They also have no known closed form solution. To enable analysis of the model we linearize it about a trajectory such that the bicycle is upright and travelling straight ahead. This linearization allows us to arrive at a parameterized linear time-invariant state-space representation of the bicycle dynamics, suitable for analysis and control design. The inner-loop control consists of a forward-speed controller as well as a lean and steer controller. To keep the bicycle at a constant forward speed, we develop a high-bandwidth proportional controller that uses a torque along the axis of the rear wheel of the bicycle to keep the angular velocity of the rear wheel at a constant setpoint. To stabilize the bicycle at this forward speed, lean torque and steer torque are treated as the control signals. We design a state-feedback controller and augment integrators to the output feedback of the lean angle and steer angle to provide perfect steady-state tracking. To arrive at the gains for state feedback, linear-quadratic regulator methods are used. When following a constant-curvature path, a vehicle has a constant yaw rate. Using this knowledge, we begin designing the outer-loop path-following control by finding a map that converts a yaw rate into appropriate lean angle and steer angle references for the inner loop. After the map is completed, system identification is performed by applying a yaw-rate reference to the map and analyzing the response of the bicycle. Using the linear approximation obtained, a classical feedback controller for yaw-rate tracking is designed. In addition to yaw-rate control, to track a path the yaw angle of the bicycle must match that of the path and the bicycle must physically be on the path. To analyze these conditions a linear approximation for the distance between the bicycle to the path is found, enabling construction of a linear approximation of the entire system. We then find that by passing the signal for the difference in yaw rate and the distance through separate controllers, summing their output, and subtracting from the reference yaw rate of the path, the bicycle converges to the path. After developing the general design procedure, the final part of the thesis shows a step by step design example and demonstrates the results of applying the proposed control architecture to the nonlinear bicycle model. We highlight some problems that can arise when the bicycle is started far from the path. To overcome these problems we develop the concept of a virtual path, which is a path that when followed returns the bicycle to the actual path. We also recognize that, in practice, typical paths do not have constant curvature, so we construct more practical paths by joining straight line segments and circular arc segments, representing a practical path similar to a path that would be encountered when biking through a series of rural roads. Finally, we finish the design example by demonstrating the performance of the control architecture on such a path. From these simulations we show that using the suggested controller design that the bicycle will converge to a constant curvature path. Additionally with using the controllers we develop that in the absence of disturbance the bicycle will stay within the intended traffic lane when travelling on a typical rural road

Advances in Mechanical Systems Dynamics 2020

The fundamentals of mechanical system dynamics were established before the beginning of the industrial era. The 18th century was a very important time for science and was characterized by the development of classical mechanics. This development progressed in the 19th century, and new, important applications related to industrialization were found and studied. The development of computers in the 20th century revolutionized mechanical system dynamics owing to the development of numerical simulation. We are now in the presence of the fourth industrial revolution. Mechanical systems are increasingly integrated with electrical, fluidic, and electronic systems, and the industrial environment has become characterized by the cyber-physical systems of industry 4.0. Within this framework, the status-of-the-art has become represented by integrated mechanical systems and supported by accurate dynamic models able to predict their dynamic behavior. Therefore, mechanical systems dynamics will play a central role in forthcoming years. This Special Issue aims to disseminate the latest research findings and ideas in the field of mechanical systems dynamics, with particular emphasis on novel trends and applications

Eco-Driving planification profile for electric motorcycles

Los perfiles de Eco-Driving son algoritmos capaces de utilizar información adicional para crear recomendaciones o limitaciones sobre las capacidades del conductor. Aumentan la autonomía del vehículo, pero actualmente su uso no está relacionado con la autonomía requerida por el conductor. Por esta razón, en este trabajo, el desafío de la conducción ecológica se traduce en un controlador óptimo de dos capas diseñado para vehículos eléctricos puros. Este controlador está orientado a asegurar que la energía disponible sea suficiente para completar un viaje demandado, agregando límites de velocidad para controlar la tasa de consumo de energía. Se exponen y analizan los modelos mecánicos y eléctricos requeridos. La función de costo está optimizada para corresponder a las necesidades de cada viaje de acuerdo con el comportamiento del conductor, el vehículo y la información de la trayectoria. El controlador óptimo propuesto en este trabajo es un controlador predictivo de modelo no lineal (NMPC) asociado a una optimización unidimensional no lineal. La combinación de ambos algoritmos permite aumentar alrededor de un 50% la autonomía con una limitación del 30% de las capacidades de velocidad y aceleración. Además, el algoritmo es capaz de asegurar una autonomía final con un 1,25% de error en presencia de ruido de sensor y actuador.The Eco-Driving profiles are algorithms capable to use additional information in order to create recommendations or limitation over the driver capabilities. They increase the autonomy of the vehicle but currently its usage is not related to the autonomy required by the driver. For this reason, in this paper, the Eco-Driving challenge is translated into two layers optimal controller designed for pure electric vehicles. This controller is oriented to ensure that the energy available is enough to complete a demanded trip, adding speed limits to control the energy consumption rate. The mechanical and electrical models required are exposed and analyzed. The cost function is optimized to correspond to the needs of each trip according to driver behavior, vehicle and trajectory information. The optimal controller proposed in this paper is a nonlinear model predictive controller (NMPC) associated to a nonlinear unidimensional optimization. The combination of both algorithms lets to increase around 50% the autonomy with a limitation of the 30% of the speed and acceleration capabilities. Also, the algorithm is capable to ensure a final autonomy with a 1.25% of error in the presence of sensor and actuator noise.Doctor en IngenieríaDoctorad

Commonsense understanding of causes of motion.

There are many findings about children's spontaneous reasoning in dynamics. These\ud studies suggest that a non-Newtonian framework is used by students across a large age range\ud but there is controversy as to whether pupils' conceptions represent systematic mental\ud structures or temporary constructions. Ogborn (1985) constructed a theory of commonsense\ud understanding of motion, which proposes a definite structure of thinking. Unlike\ud much previous work, his theory is susceptible to testing.\ud This research sets out to test this hypothesis about the content and nature of commonsense\ud ideas of motion. After preliminary work using interviews and repertory grids, a formal\ud model of the theory was constructed which provided the basis for the collection of data in\ud the main study. The adoption of a causal model of motion provided a template for linking\ud primitive abstractions such as effort and support in a natural way.\ud In order to test a large number and wide age range of subjects (7 - 16 years), a matching pairs\ud paper and pencil task was developed for the main study. Subjects were asked to distinguish\ud between examples of nine stereotypical motions by comparing the similarity or difference\ud of the causes of pairs of motions. It was then possible to test theoretical predictions of the\ud comparisons against empirical data.\ud The results suggest that people's responses can be predicted by the model but that there is\ud an improvement in the correlations with the additon of an animacy correction. An\ud independent test was carried out where the animate nature of moving objects was varied\ud systematically and it was found that this feature, previously neglected by the theoretical\ud account, was an important distinction in subjects' consideration of causes of motion. As\ud predicted, the results were similar over a considerable age range, being however better for\ud older children than the younger ones.\ud Taking account both of these results and of Piaget's description of the sensori-motor period\ud of child development, a new version of the model is proposed, and tested against the\ud available data

Improvement of semi-active control suspensions based on gain-scheduling control

This study presents the development of a non-linear control strategy for a semi-active suspension controller using a gain-scheduling structure controller. The aim of the study is to overcome the constraints of conventional control strategies and improve semi-active suspension to achieve performance close to that of full active control. Various control strategies have been investigated to improve the performance of semi-active vibration control systems. A wide range of semi-active control strategies have also been experimentally tested by researchers in the attempt to enhance the performance of semi-active suspension systems. However, the findings published in the literature indicate that there appears to be a ceiling to performance improvements with the control strategies that have been proposed to date, which is about the half of what could be achieved with full active control. The main constraint for semi-active devices such as Magnetorheological (MR) dampers is that they are only capable of providing active control forces by dissipating energy, in their active mode, and they switch to work as simple passive dampers, the passive mode, when energy injection is demanded by the associated control laws. The split in durations of time between the active and passive modes for the conventional semi-active control strategies is around 50:50. This study will focus on the development of a novel semi-active control strategy that aims to extend the duration of the active mode and hence reduce the duration of the passive mode for semi-active suspensions by using a gain-scheduling control structure that dynamically changes the control force demanded by the operating conditions. The proposed control method is applied to both vertical and lateral suspensions of a railway vehicle in this study and the improvements in ride quality are evaluated with several different track data. For the purpose of performance comparison, a semi-active controller based on skyhook damping control integrated with MR dampers and also a vehicle with passive suspensions are used as the benchmark, and are used as a reference case for assessment of the proposed design. Numerical simulations are carried out to assess the performance of the proposed gain-scheduling controller. The simulation results obtained illustrate the performance improvement of the proposed control strategy over conventional semi-active control approaches, where the ride quality of the new controller is shown to be significantly improved and comparable with that of full active control. Potentially, this kind of adaptive capability with variable control approaches can be used to deliver the level of the performance that is currently only possible with fully active suspension without incurring the associated high costs and power consumption

Peripheral visions: you would not want to be staring like that at me: the American other and the carnival spectacle in HBO’s True Blood, Deadwood and Carnivàle, & a novel, Tarnished

‘You would not want to be staring like that at me.’ The minacious words of Deadwood’s Al Swearengen ring out beyond the show’s Wild West confines and speak to the wider cultural anatomy of the United States. Swearengen is threatening his nemesis, Sheriff Bullock, who has decided to communicate his contempt for Swearengen with one, long look. Al returns this glare, his verbal riposte a mere addendum to their power struggle that is, in that moment, reaching its climactic end through a distinctly visual discourse. The visual, what we look like, what we look at and how we look at each other, the superficial dermal sign and what it signifies, not only about itself but about the viewer also, permeates and produces American subcultural interactions. Philip McGowan calls this ‘an economy of seeing’, and conceives it as a distinctly American version of the Carnivalesque that renders the act of looking a method of both highlighting and monetising difference and negating the different, of constructing and deconstructing the identities of those who do not fit into the template of the norm (white, able-bodied), and of creating a binary between this norm and an American ‘Other’, the racial, physiological, cultural outsider. McGowan traces the development of restrictive visual exchange through the chronology of the American exposition, the midway and the freak show, arguing that these public events provided a model for the paying public on how to frame and interact with this ‘Other’ in both showground and more quotidian spaces. McGowan follows this historical precedent through to its literary permutations, exploring texts that best illustrate his conceptual reframing of the Carnivalesque in distinctly American terms. I seek to take this updated framework and apply it to its other natural counterpart, serial television (HBO specifically), the filmic, opt-in, long-form narratives that have overtaken cinema as both our premier visual product and primary means of replicating, investigating and evaluating culture. The shows I have selected (True Blood, Deadwood and Carnivàle) each stand as and offer up instances of these visual behaviours through their narratives and aesthetics, depicting this normal/’Other’ binary in illuminative, intersectional and often disruptive ways. With these concerns in mind, I also present my own creative work, a novel that attempts to converge American Gothic and Western tropes (succeeding other less explicitly coalesced examples) in order to more fully materialise the inherent potential of this specific hybrid, and that was, in part, written in consideration of and as response to this critical discourse and its associated visual, cultural and historical cues