Bio-inspired retinal optic flow perception in robotic navigation

This thesis concerns the bio-inspired visual perception of motion with emphasis on locomotion targeting robotic systems. By continuously registering moving visual features in the human retina, a sensation of a visual flow cue is created. An interpretation of visual flow cues forms a low-level motion perception more known as retinal optic flow. Retinal optic flow is often mentioned and credited in human locomotor research but only in theory and simulated environments so far. Reconstructing the retinal optic flow fields using existing methods of estimating optic flow and experimental data from naive test subjects provides further insight into how it interacts with intermittent control behavior and dynamic gazing. The retinal optic flow is successfully demonstrated during a vehicular steering task scenario and further supports the idea that humans may use such perception to aid their ability to correct their steering during navigation.To achieve the reconstruction and estimation of the retinal optic flow, a set of optic flow estimators were fairly and systematically evaluated on the criteria on run-time predictability and reliability, and performance accuracy. A formalized methodology using containerization technology for performing the benchmarking was developed to generate the results. Furthermore, the readiness in road vehicles for the adoption of modern robotic software and related software processes were investigated. This was done with special emphasis on real-time computing and introducing containerization and microservice design paradigm. By doing so, continuous integration, continuous deployment, and continuous experimentation were enabled in order to aid further development and research. With the method of estimating retinal optic flow and its interaction with intermittent control, a more complete vision-based bionic steering control model is to be proposed and tested in a live robotic system

Gaze control modelling and robotic implementation

Although we have the impression that we can process the entire visual field in a single fixation, in reality we would be unable to fully process the information outside of foveal vision if we were unable to move our eyes. Because of acuity limitations in the retina, eye movements are necessary for processing the details of the array. Our ability to discriminate fine detail drops off markedly outside of the fovea in the parafovea (extending out to about 5 degrees on either side of fixation) and in the periphery (everything beyond the parafovea). While we are reading or searching a visual array for a target or simply looking at a new scene, our eyes move every 200-350 ms. These eye movements serve to move the fovea (the high resolution part of the retina encompassing 2 degrees at the centre of the visual field) to an area of interest in order to process it in greater detail. During the actual eye movement (or saccade), vision is suppressed and new information is acquired only during the fixation (the period of time when the eyes remain relatively still). While it is true that we can move our attention independently of where the eyes are fixated, it does not seem to be the case in everyday viewing. The separation between attention and fixation is often attained in very simple tasks; however, in tasks like reading, visual search, and scene perception, covert attention and overt attention (the exact eye location) are tightly linked. Because eye movements are essentially motor movements, it takes time to plan and execute a saccade. In addition, the end-point is pre-selected before the beginning of the movement. There is considerable evidence that the nature of the task influences eye movements. Depending on the task, there is considerable variability both in terms of fixation durations and saccade lengths. It is possible to outline five separate movement systems that put the fovea on a target and keep it there. Each of these movement systems shares the same effector pathway—the three bilateral groups of oculomotor neurons in the brain stem. These five systems include three that keep the fovea on a visual target in the environment and two that stabilize the eye during head movement. Saccadic eye movements shift the fovea rapidly to a visual target in the periphery. Smooth pursuit movements keep the image of a moving target on the fovea. Vergence movements move the eyes in opposite directions so that the image is positioned on both foveae. Vestibulo-ocular movements hold images still on the retina during brief head movements and are driven by signals from the vestibular system. Optokinetic movements hold images during sustained head rotation and are driven by visual stimuli. All eye movements but vergence movements are conjugate: each eye moves the same amount in the same direction. Vergence movements are disconjugate: The eyes move in different directions and sometimes by different amounts. Finally, there are times that the eye must stay still in the orbit so that it can examine a stationary object. Thus, a sixth system, the fixation system, holds the eye still during intent gaze. This requires active suppression of eye movement. Vision is most accurate when the eyes are still. When we look at an object of interest a neural system of fixation actively prevents the eyes from moving. The fixation system is not as active when we are doing something that does not require vision, for example, mental arithmetic. Our eyes explore the world in a series of active fixations connected by saccades. The purpose of the saccade is to move the eyes as quickly as possible. Saccades are highly stereotyped; they have a standard waveform with a single smooth increase and decrease of eye velocity. Saccades are extremely fast, occurring within a fraction of a second, at speeds up to 900°/s. Only the distance of the target from the fovea determines the velocity of a saccadic eye movement. We can change the amplitude and direction of our saccades voluntarily but we cannot change their velocities. Ordinarily there is no time for visual feedback to modify the course of the saccade; corrections to the direction of movement are made in successive saccades. Only fatigue, drugs, or pathological states can slow saccades. Accurate saccades can be made not only to visual targets but also to sounds, tactile stimuli, memories of locations in space, and even verbal commands (“look left”). The smooth pursuit system keeps the image of a moving target on the fovea by calculating how fast the target is moving and moving the eyes accordingly. The system requires a moving stimulus in order to calculate the proper eye velocity. Thus, a verbal command or an imagined stimulus cannot produce smooth pursuit. Smooth pursuit movements have a maximum velocity of about 100°/s, much slower than saccades. The saccadic and smooth pursuit systems have very different central control systems. A coherent integration of these different eye movements, together with the other movements, essentially corresponds to a gating-like effect on the brain areas controlled. The gaze control can be seen in a system that decides which action should be enabled and which should be inhibited and in another that improves the action performance when it is executed. It follows that the underlying guiding principle of the gaze control is the kind of stimuli that are presented to the system, by linking therefore the task that is going to be executed. This thesis aims at validating the strong relation between actions and gaze. In the first part a gaze controller has been studied and implemented in a robotic platform in order to understand the specific features of prediction and learning showed by the biological system. The eye movements integration opens the problem of the best action that should be selected when a new stimuli is presented. The action selection problem is solved by the basal ganglia brain structures that react to the different salience values of the environment. In the second part of this work the gaze behaviour has been studied during a locomotion task. The final objective is to show how the different tasks, such as the locomotion task, imply the salience values that drives the gaze

Wheeled Mobile Robots: State of the Art Overview and Kinematic Comparison Among Three Omnidirectional Locomotion Strategies

In the last decades, mobile robotics has become a very interesting research topic in the feld of robotics, mainly because of population ageing and the recent pandemic emergency caused by Covid-19. Against this context, the paper presents an overview on wheeled mobile robot (WMR), which have a central role in nowadays scenario. In particular, the paper describes the most commonly adopted locomotion strategies, perception systems, control architectures and navigation approaches. After having analyzed the state of the art, this paper focuses on the kinematics of three omnidirectional platforms: a four mecanum wheels robot (4WD), a three omni wheel platform (3WD) and a two swerve-drive system (2SWD). Through a dimensionless approach, these three platforms are compared to understand how their mobility is afected by the wheel speed limitations that are present in every practical application. This original comparison has not been already presented by the literature and it can be used to improve our understanding of the kinematics of these mobile robots and to guide the selection of the most appropriate locomotion system according to the specifc application

Bioinspired Implementation and Assessment of a Remote-Controlled Robot

This research was funded by the Universidad de Las Americas, Direccion General de Investigacion.Daily activities are characterized by an increasing interaction with smart machines that present a certain level of autonomy. However, the intelligence of such electronic devices is not always transparent for the end user. This study is aimed at assessing the quality of the remote control of a mobile robot whether the artefact exhibits a human-like behavior or not. The bioinspired behavior implemented in the robot is the well-described two-thirds power law. The performance of participants who teleoperate the semiautonomous vehicle implementing the biological law is compared to a manual and nonbiological mode of control. The results show that the time required to complete the path and the number of collisions with obstacles are significantly lower in the biological condition than in the two other conditions. Also, the highest percentage of occurrences of curvilinear or smooth trajectories are obtained when the steering is assisted by an integration of the power law in the robot's way of working. This advanced analysis of the performance based on the naturalness of the movement kinematics provides a refined evaluation of the quality of the Human-Machine Interaction (HMI). This finding is consistent with the hypothesis of a relationship between the power law and jerk minimization. In addition, the outcome of this study supports the theory of a CNS origin of the power law. The discussion addresses the implications of the anthropocentric approach to enhance the HMI.publishersversionpublishe

Climbing and Walking Robots

With the advancement of technology, new exciting approaches enable us to render mobile robotic systems more versatile, robust and cost-efficient. Some researchers combine climbing and walking techniques with a modular approach, a reconfigurable approach, or a swarm approach to realize novel prototypes as flexible mobile robotic platforms featuring all necessary locomotion capabilities. The purpose of this book is to provide an overview of the latest wide-range achievements in climbing and walking robotic technology to researchers, scientists, and engineers throughout the world. Different aspects including control simulation, locomotion realization, methodology, and system integration are presented from the scientific and from the technical point of view. This book consists of two main parts, one dealing with walking robots, the second with climbing robots. The content is also grouped by theoretical research and applicative realization. Every chapter offers a considerable amount of interesting and useful information

ALTERNATE FOOT PLACEMENT: INVESTIGATING THE ROLE OF GAIT PARAMETERS, PLANAR OBSTACLE COMPLEXITY, AND ATHLETIC TRAINING

On a daily basis modifications, based upon environmental demands and the capabilities of the individual, are made to the locomotor pattern to enable avoidance of undesirable landing areas (i.e. planar obstacles). Athletes and dancers have been suggested to have superior perception-action coupling compared to non-athletes, allowing them to perform various tasks at a greater speed without a loss of precision (Federici et al., 2005; Gerin-Lajoie et al. (2007). The current study assessed non-athletes, dancers, and field athletes to investigate whether training influences the maintenance of forward progression and stability in relation to alternate foot placement during planar obstacle avoidance. Eleven field athletes (22± 2.68 years) having recent/ current sport participation, 10 individuals (21.1± 1.1 years) with previous/current dance training, and 12 non-athletes (21.75± 1.54 years) with no participation in organized sport in \u3e5 years were asked to walk to a goal (~13 m away) at a self-selected pace, avoiding any obstacle(s) when present (50% of trials; 15cm wide x 70cm long rectangles, projected ~8m from the start position). Obstacle conditions were: 1) Single obstacle appearance (SIN) where the obstacle (at N) appeared when the participant was 2 steps away from the first obstacle (N-2) ; 2) Double obstacle appearance was delayed (DDEL) until at N-2; and 3) Double obstacle appearance after participants reached steady state (i.e. ~3 steps from start)(DSS). All participants, regardless of training, stepped medially during SIN. Avoidance during double obstacle conditions was variable (i.e. medial-medial, medial-lateral, and lateral-medial). The variability of behaviour, computed as a coefficient of unalikeability (the proportion of possible comparisons which are unalike), had significant moderate positive correlations with the minimum Dynamic Stability Margin at N-1 for DSS and DDEL (r = 0.36; r = 0.44, respectively, p\u3c0.001) and a significant weak positive relationship with ML COM variability (r = 0.28, p\u3c0.05) during DDEL. To a degree, greater ML COM variability leads to avoidance behaviour that exploits forward progression more so than stability, as stepping medially perturbs the COM the least from its forward momentum but narrows the BOS creating instability that must be offset in the following step. Avoidance of planar obstacles at a comfortable walk lacked context specificity to dance or field sport training to elicit any behavioural differences

Development of a Bio-inspired GNS methodology in the dark environment

The current research explores the connection between gazing and locomotion of acoustic guided animals and the application of this in autonomous vehicles guidance and navigation strategies. Research groups worldwide are currently investigating different technologies and autonomous guidance algorithm-based strategies. The use of nature-inspired innovations ensures both the efficiency and the robustness of guidance strategies. The current research looks to fill the lack of research of those methodologies using bio-inspired techniques for acoustic guided animals as only visual-based methodologies have been implemented for a variety of tasks. Also, to connect the results from bat¿s flight experiments of Moss et al. with the Tau Theory of David Lee. The connection between the Tau Theory and flight dynamics and manoeuvring is another interesting topic not only for autonomous navigation but also for handling qualities and safety improvement. After carrying out a data analysis of Bat¿s flight experiments through the cluttering of the environment and connecting the flight behaviour with the extensive research done upon environmental cues perception guiding locomotion action for visual and acoustic cues. This concept is in an early phase of development and therefore, the aim is to set the baseline for further research on the topic. Results showed that bats perform a controlled braking manoeuvre when closing gaps, which is coined the term ¿Energised Approach¿. However, biased errors were found in some cases hence the results were negatively impacted, causing the results to be inaccurate in certain phases of the analysis. Despite the error found post-analysis, the results found in this research can still be considered insightful however artificial intelligence algorithms should be incorporated in future studies in order to achieve a more accurate result and finding.Outgoin