Extended crossover model for human-control of fractional order plants

A data-driven generalization of the crossover model is proposed, characterizing the human control of systems with both integer and fractional-order plant dynamics. The model is developed and validated using data obtained from human subjects operating in compensatory and pursuit tracking tasks. From the model, it is inferred that humans possess a limited but consistent capability to compensate for fractional-order plant dynamics. Further, a review of potential sources of fractionality within such man–machine systems suggests that visual perception, based on visual cues that contain memory, and muscular dynamics are likely sources of fractional-order dynamics within humans themselves. Accordingly, a possible mechanism for fractional-order compensation, operating between visual and muscular sub-systems, is proposed. Deeper analysis of the data shows that human response is more highly correlated to fractional-order representations of visual cues, rather than directly to objective engineering variables, as is commonly proposed in human control models in the literature. These results are expected to underpin future design developments in human-in-the-loop cyber-physical systems, for example, in semi-autonomous highway driving

Slower Visuomotor Corrections with Unchanged Latency are Consistent with Optimal Adaptation to Increased Endogenous Noise in the Elderly

We analyzed age-related changes in motor response in a visuomotor compensatory tracking task. Subjects used a manipulandum to attempt to keep a displayed cursor at the center of a screen despite random perturbations to its location. Cross-correlation analysis of the perturbation and the subject response showed no age-related increase in latency until the onset of response to the perturbation, but substantial slowing of the response itself. Results are consistent with age-related deterioration in the ratio of signal to noise in visuomotor response. The task is such that it is tractable to use Bayesian and quadratic optimality assumptions to construct a model for behavior. This model assumes that behavior resembles an optimal controller subject to noise, and parametrizes response in terms of latency, willingness to expend effort, noise intensity, and noise bandwidth. The model is consistent with the data for all young (n = 12, age 20–30) and most elderly (n = 12, age 65–92) subjects. The model reproduces the latency result from the cross-correlation method. When presented with increased noise, the computational model reproduces the experimentally observed age-related slowing and the observed lack of increased latency. The model provides a precise way to quantitatively formulate the long-standing hypothesis that age-related slowing is an adaptation to increased noise

Humanoid Robots

For many years, the human being has been trying, in all ways, to recreate the complex mechanisms that form the human body. Such task is extremely complicated and the results are not totally satisfactory. However, with increasing technological advances based on theoretical and experimental researches, man gets, in a way, to copy or to imitate some systems of the human body. These researches not only intended to create humanoid robots, great part of them constituting autonomous systems, but also, in some way, to offer a higher knowledge of the systems that form the human body, objectifying possible applications in the technology of rehabilitation of human beings, gathering in a whole studies related not only to Robotics, but also to Biomechanics, Biomimmetics, Cybernetics, among other areas. This book presents a series of researches inspired by this ideal, carried through by various researchers worldwide, looking for to analyze and to discuss diverse subjects related to humanoid robots. The presented contributions explore aspects about robotic hands, learning, language, vision and locomotion

A Theory of Reaction Time Distributions

We develop a general theory of reaction time (RT) distributions in psychological experiments, deriving from the distribution of the quotient of two normal random variables, that of the task difficulty (top-down information), and that of the external evidence that becomes available to solve it (bottom-up information). The theory provides a unied account of known changes in the shape of the distributions depending on properties of the task and of the participants, and it predicts additional changes that should be observed. A number of known properties of RT distributions are homogeneously accounted\ud for by variations in the value of two easily interpretable parameters: the coefficients of variation of the two normal variables. The predictions of the theory are compared with those of multiple families of distributions that have been proposed to account for RTs, indicating our theory provides a significantly better account of experimental data. For this purpose, we provide comparisons with four large datasets across tasks and modalitities. Finally,\ud we show how the theory links to neurobiological models of response latencies

Complex, but flexible neural encoding of arm movements in the macaque parietal cortex

A central role in interacting with the environment is played by higher cortical areas, in which neurons are often sensitive to multiple features of the external world. This type of encoding is termed ‘mixed selectivity’ and it greatly expands the complexity of neural representations, making the neural code more reliable and flexible. Past studies demonstrated that the medial posterior parietal area V6A in the macaque is tuned by many aspects of reaching movements, thus it is likely to contain ‘mixed selectivity’ neurons. Here, we used Generalized Linear Models (GLMs) to simultaneously evaluate the contribution of several factors upon V6A cells during a fix-to-reach task and directly test this hypothesis. The activity of 181 V6A neurons has been recorded from 2 Macaca fascicularis during a foveated delayed reaching task performed towards 9 different targets in the darkness. During the first step of the fitting procedure, LASSO optimization was used to remove from the model the regressors with a negligible effect. Then many models were estimated and subsequently compared, leading to the definition of a ‘functional fingerprint’ representative of the properties of each unit. The analysis of the ‘functional fingerprints’ highlighted the virtual absence of units strictly selective for only one factor, revealing that most cells are characterized by ‘mixed selectivity’. The population resulted ‘category free’, with no evidence for any functional segregation. We also found that the spatial tuning of the population reached a peak during the movement phase, but overall a motor code is maintained along the entire task. Finally, the previous spiking history of each cell resulted extremely relevant to explain the neural modulations for most neurons (62%). In conclusion, the presence of ‘mixed selectivity’ in area V6A, highly expected but never directly tested before, supports the growing emphasis on the importance of neurons exhibiting complex neural behaviours

Efficient resource allocation for automotive active vision systems

Individual mobility on roads has a noticeable impact upon peoples' lives, including traffic accidents resulting in severe, or even lethal injuries. Therefore the main goal when operating a vehicle is to safely participate in road-traffic while minimising the adverse effects on our environment. This goal is pursued by road safety measures ranging from safety-oriented road design to driver assistance systems. The latter require exteroceptive sensors to acquire information about the vehicle's current environment. In this thesis an efficient resource allocation for automotive vision systems is proposed. The notion of allocating resources implies the presence of processes that observe the whole environment and that are able to effeciently direct attentive processes. Directing attention constitutes a decision making process dependent upon the environment it operates in, the goal it pursues, and the sensor resources and computational resources it allocates. The sensor resources considered in this thesis are a subset of the multi-modal sensor system on a test vehicle provided by Audi AG, which is also used to evaluate our proposed resource allocation system. This thesis presents an original contribution in three respects. First, a system architecture designed to efficiently allocate both high-resolution sensor resources and computational expensive processes based upon low-resolution sensor data is proposed. Second, a novel method to estimate 3-D range motion, e cient scan-patterns for spin image based classifiers, and an evaluation of track-to-track fusion algorithms present contributions in the field of data processing methods. Third, a Pareto efficient multi-objective resource allocation method is formalised, implemented, and evaluated using road traffic test sequences

Modelling Human-Driver Behaviour Using a Biofidelic Approach

This dissertation is concerned with the subject of modelling human steering control of ground vehicles. Special care has been taken with respect to designing a model that is biofidelic, i.e., a model that operates according to the principles of human control. With this aim, first classical human control theory has been revisited, both from a literature review and an experimental perspective; data have been recorded from test subjects in compensatory and pursuit tracking tasks. The tracking experiments are the first ever to be performed with fractional order plants, which are plants suitable to represent system memory. From the data, an extension of the Crossover model by McRuer’s is designed, to include the control of such category of plants. The proposed model is referred to as the Fractional Crossover Model. This is followed by a study on modelling memory in human-machine systems from a classical control theory viewpoint. These results broaden the existing array of manual control modelling techniques and can be employed in a modular manner, combined with current models. More significantly – and still with respect to the domain of generic human control and human-machine systems – a new approach for modelling the human-operator is proposed. This approach consists in treating the problem from a statistical viewpoint. With this methodology a novel human control model based on multiplicative dynamics is presented. The model, which was inspired on actual results in neuroscience, is validated with the tracking data obtained from test subjects and by comparing it to classical models in the literature. Hence the model is useful to analyse human performance or to reproduce human control in simulation, field tests or in the video game industry. With respect to steering control modelling, which is the main topic of this dissertation, additional experiments with test subjects were conducted in a simple vehicle simulator – with hardware and software specifically developed during this research program to test multiple hypotheses. The data were analysed with the intent of identifying which optical variables drivers employ while controlling a vehicle on public roads; it is seen that the splay angles– which are the projections of the road lines on the retina – are likely candidates for lane keeping at low speeds. This brings on a novel human-centred driver model first proposed here. This model includes multiplicative human control over the splay angles, and far-point error perception for lane keeping at higher speeds. The human-centred model has its domain of applicability in the intelligent transportation industry, in particular for the development of shared control systems and advanced driver-assistance systems for semi-autonomous ground vehicles. Additionally, the model can be employed in field testing of ground vehicles – for example, in vehicle durability tests. Furthermore, the topic of alternative steering devices for driving autonomous and semi-autonomous vehicles is investigated. This leads to another of the contributions in this dissertation. Here it is proposed that for such vehicles, and for the control of systems with a shared control perspective, anisometric steering wheel can be advantageous under certain schemes – tight rein or loose rein modes according to the H-metaphor. This is supported by additional data collected in the driving simulation experiments. Resulting from this, fractional order transfer functions are employed to increment steering stability and control accuracy with the isometric device. This prototypical steering system is applicable for the control of ground vehicles with the so-called by-wire controls, which are already incorporated in some commercially available vehicles

The Economy Of Typography (the Arrangement or Mode of Operation of Typography)

The thesis will show that the current research into legibility and readability regarding certain aspects or characters of type is incomplete, and will demonstrate what further research is necessary to complete the analysis of these aspects or characters in the economy of typography in continuous text. Chapter 1 will show that the development of reading depends on the legibility of the typography and characters ‘recognizing patterns, planning strategy, and feeling’ in other words reading and writing are interdependent all depend in some part on the construction of the characters and their relationship to each other. It will also show that readable writing is desirable and important for the reader’s sake. Chapter 2 will deal with the practical presentation of the characters of what the reading public read, and the role played by legibility and readability of typography in conveying their message. Printers and designers will also have a working knowledge and experience of legibility and readability which is incorporated into typograhy presentations, and this also is taken into account in chapter 2. Chapter 3 reviews the criteria and methods used in typography readability and legibility research. The research will show that readability is the ease with which the eye can absorb the message and move along the line, and legibility is based on the ease with which one letter can be identified from another. Chapter 4 entitled Analysis and Recommendations concludes the thesis with a summary of chapters 1, 2 and 3 before presenting a comparative analysis of current research into legibility, with particular emphasis on misreading or misrecognition of characters, and provides illustrations of the conclusions reached by way of bar chart and tables. Appendix One of the thesis contains a comprehensive list of the research into legibility and readability. Appendix Two contains the graphics of Benjamin Sherbow showing typography layout supportive of type spacing matters discussed in chapter 2. The thesis has an extensive bibliography of the works referred to throughout the thesis