Just Around the Corner: The Impact of Instruction Method and Corner Geometry on Teleoperation of Virtual Unmanned Ground Vehicles

Teleoperated robots have proven useful across various domains, as they can more readily search for survivors, survey collapsed and structurally unsound buildings, map out safe routes for rescue workers, and monitor rescue environments. A significant drawback of these robots is that they require the operator to perceive the environment indirectly. As such, camera angles, uneven terrain, lighting, and other environmental conditions can result in robots colliding with obstacles, getting stuck in rubble, and falling over (Casper & Murphy, 2003). To better understand how operators remotely perceive and navigate unmanned ground vehicles, the present work investigated operators’ abilities to negotiate corners of varying widths. In Experiment 1, we evaluated how instruction method impacts cornering time and collisions, looking specifically at the speed-accuracy tradeoff for negotiating corners. Participants navigated a virtual vehicle around corners under the instruction to focus on accuracy (i.e., avoiding collisions) or speed (i.e., negotiating the corners as quickly as possible). We found that as the task became more difficult, subjects’ cornering times increased, and their probability of successful cornering decreased. We also demonstrated that the Fitts’ law speed-accuracy tradeoff could be extended to a cornering task. In Experiment 2, we challenged two of the assumptions of Pastel et al.’s (2007) cornering law and assessed how corner angle and differences in path widths impacted cornering time. Participants navigated a virtual vehicle around corners of varying angles (45°, 90°, and 135°) and varying path widths. We found that increases in corner angle resulted in increased cornering times and a decreased probability of successful cornering. The findings from these experiments are applicable to contexts where an individual is tasked with remotely navigating around corners (e.g., video gaming, USAR, surveillance, military operations, training)

The Effect of Anthropometric Properties of Self-Avatars on Action Capabilities in Virtual Reality

The field of Virtual Reality (VR) has seen a steady exponential uptake in the last decade and is being continuously incorporated into areas of popular interest like healthcare, training, recreation and gaming. This steady upward trend and prolonged popularity has resulted in numerous extravagant virtual environments, some that aim to mimic real-life experiences like combat training, while others intend to provide unique experiences that may otherwise be difficult to recreate like flying over ancient Egypt as a bird. These experiences often showcase highly realistic graphics, intuitive interactions and unique avatar embodiment scenarios with the help of various tracking sensors, high definition graphic displays, sound systems, etc. The literature suggests that estimates and affordance judgments in VR scenarios such as the ones described above are affected by the properties and the nature of the avatar embodied by the user. Therefore, to provide users with the finest experiences it is crucial to understand the interaction between the embodied self and the action capabilities afforded by it in the surrounding virtual environment. In a series of studies aimed at exploring the effect of gender matched body-scaled self-avatars on the user\u27s perception, we investigate the effect of self-avatars on the perception of size of objects in an immersive virtual environment (IVE) and how this perception affects the actions one can perform as compared to the real world. In the process, we make use of newer tracking technology and graphic displays to investigate the perceived differences between real world environments and their virtual counterparts to understand how the spatial properties of the environment and the embodied self-avatars affect affordances by means of passability judgments. We describe techniques for creation and mapping VR environments onto their real world counterparts and the creation of gender matched body-scaled self-avatars that provides real time full-body tracking. The first two studies investigate how newer graphical displays and off-the-shelf tracking devices can be utilized to create salient gender matched body-scaled self-avatars and their effect on the judgment of passability as a result of the embodied body schema. The study involves creating complex scripts that automate the process of mapping virtual worlds onto their real world counterparts within a 1cm margin of error and the creation of self-avatars that match height, limb proportions and shoulder width of the participant using tracking sensors. The experiment involves making judgments about the passability of an adjustable doorway in the real world and in a virtual to-scale replica of the real world environment. The results demonstrated that the perception of affordances in IVEs is comparable to the real world but the behavior leading to it differs in VR. Also, the body-scaled self-avatars generated provide salient information yielding performance similar to the real world. Several insights and guidelines related to creating veridical virtual environments and realistic self-avatars were achieved from this effort. The third study investigates how the presence of body-scaled self-avatars affects the perception of size of virtual handheld objects and the influence of the person-plus-virtual-object system created by lifting the said virtual object on passability. This is crucial to understand as VR simulations now often utilize self-avatars that carry objects while maneuvering through the environment. How they interact with these handheld objects can influence what they do in critical scenarios where split second decisions can change the outcome like combat training, role-playing games, first person shooting, thrilling rides, physiotherapy, etc. It has also been reported that the avatar itself can influence the perception of size of virtual objects, in turn influencing action capabilities. There is ample research on different interaction techniques to manipulate objects in a virtual world but the question about how the objects affect our action capabilities upon interaction remains unanswered, especially when the haptic feedback associated with holding a real object is mismatched or missing. The study investigates this phenomenon by having participants interact with virtual objects of different sizes and making frontal and lateral passability judgments to an adjustable aperture similar to the first experiment. The results suggest that the presence of self-avatars significantly affects affordance judgments. Interestingly, frontal and lateral judgments in IVEs seem to similar unlike the real world. Investigating the concept of embodied body schema and its influence on action-capabilities further, the fourth study looks at how embodying self-avatars that may vary slightly from your real world body affect performance and behavior in dynamic affordance scenarios. In this particular study, we change the eye height of the participants in the presence or absence of self-avatars that are either bigger, smaller or the same size as the participant. We then investigate how this change in eye height and anthropometric properties of the self-avatar affects their judgments when crossing streets with oncoming traffic in virtual reality. We also evaluate any changes in the perceived walking speed as a result of embodying altered self-avatars. The findings suggest that the presence of self-avatars results in safer crossing behavior, however scaling the eye height or the avatar does not seem to affect the perceived walking speed. A detailed discussion on all the findings can be found in the manuscript

Comparative Analysis of Static Loading Performance of Rigid and Flexible Road Wheel based on Finite Element Method

To overcome the shortcomings of traditional rigid road wheel, such as poor damping effect and low load-bearing efficiency, a new type of flexible road wheel, having a unique suspension-bearing mode, was introduced. The three-dimensional nonlinear finite element model of rigid and flexible road wheel, considering the triple nonlinear characteristics of geometry, material and contact, is established for numerical investigation of static loading performance. The accuracy of the finite element model of the rigid and flexible road wheel is verified by static loading experiment. The static loading performance of the rigid and flexible road wheels is numerically analyzed. The influence of vertical load on maximum stress and deformation of the rigid and flexible wheels is also studied. The results show that the contact pressure uniformity of the flexible road wheel is better than that of the rigid road wheel under the static vertical load, but the maximum stress and deformation of the flexible road wheel are greater than that of the rigid road wheel. However, this problem can be solved by increasing the number of hinge sets and optimising the joints. The research results provide theoretical basis for replacing rigid road wheel with flexible road wheel, and also provide reference for structural optimisation of flexible road wheel

Development and evaluation of 4WSS electric-driven chassis for high-clearance sprayer

IntroductionThe high clearance sprayer with conventional steering mechanisms, as an intelligent spraying machine, is frequently stuck or broken in muddy fields due to the excessive torque load.MethodsA Four-Wheel Self-Steering (4WSS) electric-driven chassis with a smaller turning radius and better passability is developed to handle complex agricultural terrains. The 4WSS chassis is mainly composed of two custom-designed steering bridges and four in-wheel drive motors. It can achieve steering and driving forward simultaneously through coordinate differential speed control of drive motors, saving a set of dedicated servo steering systems and requiring less torque during steering compared to conventional structures. A kinematic model depicting the speed relationships between four wheels is established via geometric analysis, and a Speed Distribution Controller (SDC) is designed to accomplish locomotion objectives.ResultsExperimental results demonstrate the effectiveness of the new prototype 4WSS chassis system in tracking speed and steering angle. Compared to conventional agricultural chassis, the 4WSS chassis has a smaller turning radius of 2,877 mm. DiscussionThe 4WSS chassis exhibits superior performance in typical field conditions, including muddy terrain, deep gullies, and ridges

A Closed-Loop Shared Control Framework for Legged Robots

Shared control, as a combination of human and robot intelligence, has been deemed as a promising direction toward complementing the perception and learning capabilities of legged robots. However, previous works on human–robot control for legged robots are often limited to simple tasks, such as controlling movement direction, posture, or single-leg motion, yet extensive training of the operator is required. To facilitate the transfer of human intelligence to legged robots in unstructured environments, this article presents a user-friendly closed-loop shared control framework. The main novelty is that the operator only needs to make decisions based on the recommendations of the autonomous algorithm, without having to worry about operations or consider contact planning issues. Specifically, a rough navigation path from the operator is smoothed and optimized to generate a path with reduced traversing cost. The traversability of the generated path is assessed using fast Monte Carlo tree search, which is subsequently fed back through an intuitive image interface and force feedback to help the operator make decisions quickly, forming a closed-loop shared control. The simulation and hardware experiments on a hexapod robot show that the proposed framework gives full play to the advantages of human–machine collaboration and improves the performance in terms of learning time from the operator, mission completion time, and success rate than comparison methods

Virtual Reality Interface Factors in a Power Wheelchair Simulator

Power wheelchairs (PWCs) can improve users’ quality of life by enabling them to participate in the activities of daily living, decreasing their dependence on human assistance. PWC users are faced with restricted environments, with limited space to manoeuvre, and are therefore vulnerable to collisions and injuries. To use a PWC effectively and safely, individuals must undertake training and assessment of their competency. There is significant potential for the use of virtual reality in the training and assessment of PWC users. To date, there is no standard tool available for PWC assessment and training. Rather, clinics use their own observation measurer and assessment is often largely based on guesswork. Several simulators have been developed to help the training of PWC users, yet the study of virtual assessment is an under-researched area. In fact, most simulators offer only very limited functionality and rely solely on client-centric information. For the development of a useful simulator, it is important to identify and evaluate interface factors affecting perception, behaviour, experience, and driving performance from both the user’s and clinician’s perspectives. In this thesis, issues with current PWC simulators were identified and investigated, with the intention of providing a suitable research platform for the advancement of bringing PWC simulator into clinical use. The aspects investigated include the interaction device, perception and behaviour, and virtual assessment. Three systems were developed to test each of these areas by incorporating theories and techniques from computer science and human-computer interaction. The first experiment answered the question, “which input devices are necessary and appropriate, and which virtual input device representations can and should be implemented for PWC simulation?” A proprietary PWC joystick was compared to a standard gaming joystick, and driving performance and experience were measured. Four experimental conditions (comprising two virtual input modalities and their two real-world counterparts) were studied. The findings suggest that performance is enhanced when the PWC joystick is represented and that the gaming joystick is adequate for PWC simulation. The second study investigated the question, “how do immersion factors influence behaviour, perception and sense of presence when navigating a PWC simulator?” The evaluated immersion factors include display type (head mounted display vs. monitor), field of view (changeable vs. static), and avatar presence (present vs. absent). User perception (explicit judgement of doorframe passability) and embedded behaviour (implicit measure of gap passability) were measured, based on the user’s decisions during the experiment. The results show that all three factors affect the user’s sense of presence. The display type affected both perceptual and behavioural measures, whereas field of view only affected behavioural measures. The final experiment explored the question, “how accurately can clinicians assess driving tasks in the virtual environment compared to the real world?” This study evaluated the effect of three observational techniques (viewpoints) on clinician assessment of PWC driving tasks. In addition, perceived ease of use, confidence level, and sense of presence were also examined. Observational techniques include walk, orbit, and standard viewpoints. The findings of this study suggest that clinicians could make accurate judgments and experience a high confidence level when they were able to walk or orbit the viewpoint. The results from all experiments provide general design guidelines for future virtual reality applications, in particular, PWC simulator design

ОСОБЕННОСТИ РАБОТЫ УБОРОЧНОЙ ТЕХНИКИ НА СЛАБОНЕСУЩИХ ГРУНТАХ В ДАЛЬНЕВОСТОЧНОМ РЕГИОНЕ

The authors based on own researches established actual problems of harvesting in the Amur region: ensuring passability of machines on the waterlogged soil, need of machines adaptivising to technologies of soybean harvesting, transfer of a part of the combine fleet to a caterpillar track, implementation of reloading reducing impact on the soil technologies of harvesting, increase in cost efficiency of mashines use and postharvest drying of grain and corn.Perspective solutions of problems are shown: design development of caterpillar end trucks of combines with the rubber-reinforced tracks (RRT); engineering and production of the soybean-grain harvester with RRT or a set of devices for the grain harvester with RRT as the option transferring it to the category the soybean-grain ones; process development to provide harvesting of soybean heap by the machine with RRT which crush and spread straw across the field simultaneous, to deliver soybean heap to stationary point of postharvest handling for the subsequent separation into seeds, marketable soybean and a soy chaff as valuable protein feed for livestock production, ready for feeding and storage; engineering of the forage harvester with RRT on a block and modular basis, that is based on the multipurpose power mean on RRT with the 4-machine scheme of a hydrostatic power drive of a undercarriager; development of a design of caterpillar blocks with triangular shape of contour; implementation of reloading technologies of harvest operations on system VIMLIFT.Production of harvest transport vehicles should be performed on a block and modular basis - in the form of a complex of self-propelled agricultural machines based on the released multipurpose power module with a set of the replaceable technological adapters providing its loading within a year. The agroterm of corn on grain harvesting should be delayed to later time when grain reaches standard humidity naturally.На основании исследований авторы выявили актуальные задачи уборочных работ в Амурской области: обеспечение проходимости машин по переувлажненной почве, необходимость адаптирования машин к технологиям уборки сои, перевод части комбайнового парка на гусеничный ход, внедрение перегрузочных почвощадящих технологий уборки, повышение экономической эффективности машиноиспользования и послеуборочной сушки зерна колосовых и кукурузы. Показаны перспективные пути решения этих проблем: совершенствование конструкции гусеничных ходовых тележек комбайнов на резиноармированных гусеницах (РАГ); разработка и производство соезернового комбайна на РАГ или комплекта приспособлений к зерноуборочному комбайну на РАГ как опции, переводящей его в разряд соезерновых; разработка технологии, обеспечивающей сбор зерносоевого вороха полевой машиной на РАГ с одновременным измельчением и разбрасыванием соломы по полю, доставку зерносоевого вороха на стационарный пункт послеуборочной обработки для последующего разделения на семенное, товарное зерно и соевую полову как ценный белковый корм для животноводства, готовый для скармливания и хранения; разработка кормоуборочного комбайна на РАГ на блочно-модульной основе, то есть на базе универсального энергосредства на РАГ с 4-машинной схемой объемного гидропривода ходовой части; совершенствование конструкции гусеничных блоков с треугольной формой обвода; реализация перегрузочных технологий уборочных работ по системе ВИМЛИФТ. Производство уборочно-транспортных машин должно осуществляться на блочно-модульной основе - в виде комплекса самоходных сельскохозяйственных машин на базе высвобождаемого гибкого энергомодуля с комплектом сменных технологических адаптеров, обеспечивающих его загрузку в течение года. Агросрок уборки кукурузы на зерно следует перенести на более позднее время, когда зерно естественным образом достигает кондиционной влажности