Catching what we can't see: manual interception of occluded fly-ball trajectories

Control of interceptive actions may involve fine interplay between feedback-based and predictive mechanisms. These processes rely heavily on target motion information available when the target is visible. However, short-term visual memory signals as well as implicit knowledge about the environment may also contribute to elaborate a predictive representation of the target trajectory, especially when visual feedback is partially unavailable because other objects occlude the visual target. To determine how different processes and information sources are integrated in the control of the interceptive action, we manipulated a computer-generated visual environment representing a baseball game. Twenty-four subjects intercepted fly-ball trajectories by moving a mouse cursor and by indicating the interception with a button press. In two separate sessions, fly-ball trajectories were either fully visible or occluded for 750, 1000 or 1250 ms before ball landing. Natural ball motion was perturbed during the descending trajectory with effects of either weightlessness (0 g) or increased gravity (2 g) at times such that, for occluded trajectories, 500 ms of perturbed motion were visible before ball disappearance. To examine the contribution of previous visual experience with the perturbed trajectories to the interception of invisible targets, the order of visible and occluded sessions was permuted among subjects. Under these experimental conditions, we showed that, with fully visible targets, subjects combined servo-control and predictive strategies. Instead, when intercepting occluded targets, subjects relied mostly on predictive mechanisms based, however, on different type of information depending on previous visual experience. In fact, subjects without prior experience of the perturbed trajectories showed interceptive errors consistent with predictive estimates of the ball trajectory based on a-priori knowledge of gravity. Conversely, the interceptive responses of subjects previously exposed to fully visible trajectories were compatible with the fact that implicit knowledge of the perturbed motion was also taken into account for the extrapolation of occluded trajectories

Estimating motion and time to contact in 3D environments: Priors matter

[eng] Until the present moment, an extensive amount of research has been done on how humans estimate motion or parameters of a task, such as the timeto- contact in simple scenarios. However, most avoid questioning how we extract 3D information from 2D optic information. A Bayesian approach based on a combination of optic and prior knowledge about statistical regularities of the environment would allow solving the ambiguity when translating 2D into 3D estimates. The present dissertation aims to analyse if the estimation of motion and time-to-contact in complex 3D environments is compatible with a combination of visual and prior information. In the first study, we analyse the predictions of a Bayesian model with a preference for slow speeds to estimate the direction of an object. The information available to judge movement in depth is much less precise than information about the lateral movement. Thus, combining both sources of information with a prior with preference for low speeds, estimates of motion in depth will be proportionally more attracted to low speeds than estimates of lateral motion. Thus, the perceived direction would depend on stimulus speed when estimating the ball’s direction. Our experimental results showed that the bias in perceived direction increased at higher speeds, which would be congruent with increasingly less precise motion estimates (consistent with Weber’s law). In the second study, we analyse the existing evidence on using a priori knowledge of the Earth’s gravitational acceleration and the size of objects to estimate the time to contact in parabolic trajectories. We analysed the existing evidence for using knowledge of the Earth’s gravity and the size of an object in the interaction with the surrounding environment. Next, we simulate predictions of the GS model. This model allows predicting the time to contact based on a combination of a priori variables (gravity and ball size) and optic variables. We compare the accuracy of the predictions of time-to-contact with an alternative only using optic variables, showing that relying on priors of gravitation and ball size solves the ambiguity in the estimation of the time-to-contact. Finally, we offer scenarios where the GS model would lead to predictions with systematic errors, which we will test in the following studies. In the third study, we created trajectories for which the GS model gives accurate predictions of the time to contact at different flight times but provides different systematic errors at any other time. We hypothesized that if the ball’s visibility is restricted to a short time window, the participants would prefer to see the ball during the time windows in which the model predictions are accurate. Our results showed that observers preferred to use a relatively constant ball viewing time. However, we showed evidence that the direction of the errors made by the participants for the different trajectories tested corresponded to the direction predicted by the GS model. In the fourth and final study, we investigated the role of a priori knowledge of the Earth’s gravitational acceleration and ball size in estimating the time of flight and the direction of motion of an observer towards the interception point. We introduced our participants in an environment where both gravitational acceleration and ball size was randomized trial-to-trial. The observers’ task was to move towards the interception point and predict the remaining flight time after a short occlusion. Our results provide evidence for using prior knowledge of gravity and ball size to estimate the time-to-contact. We also find evidence that gravitational acceleration may play a role in guiding locomotion towards the interception point. In summary, in this thesis, we contribute to answering a fundamental question in Perception: how we interpret information to act in the world. To do so, we show evidence that humans apply their knowledge about regularities in the environment in the form of a priori knowledge of the Earth’s gravitational acceleration, the size of the ball, or that objects stand still in the world when interpreting visual information.[spa] Hasta el momento, se ha realizado una gran cantidad de investigación sobre como el ser humano estima el movimiento o los parámetros de una tarea como el tiempo de contacto en escenarios simples. Sin embargo, la mayoría evita preguntarse cómo se extrae la información 3D a partir de la información óptica 2D. Un enfoque bayesiano basado en una combinación de información óptica y a priori sobre regularidades estadísticas del entorno interiorizadas en forma de conocimiento permitiría resolver la ambigüedad a la hora de traducir claves ópticas en 2D a estimaciones sobre propiedades del mundo en 3D. El objetivo de esta tesis es analizar si la estimación del movimiento y del tiempo de contacto en entornos 3D complejos es compatible con una combinación de información visual y a priori. En el primer estudio, se analizan las predicciones de un modelo bayesiano con preferencia por las velocidades lentas para la estimación de la dirección de un objeto. La información disponible para juzgar el movimiento en profundidad es mucho menos precisa que la información sobre el movimiento lateral. Así, cuando se combinan ambas fuentes de información con un prior con preferencia por la velocidad baja, las estimaciones del movimiento en profundidad serán proporcionalmente más atraídas por el prior que las estimaciones del movimiento lateral. Por lo tanto, la dirección percibida dependería de la velocidad del estímulo. Nuestros resultados experimentales mostraron que el sesgo en la dirección percibida aumentaba a velocidades más altas, lo que sería congruente con estimaciones de movimiento cada vez menos precisas (consistente con la ley de Weber). En el segundo estudio, analizamos las evidencias existentes sobre el uso del conocimiento a priori de la aceleración gravitatoria de la Tierra y el tamaño de los objetos para estimar el tiempo de contacto en trayectorias parabólicas. Analizamos las pruebas existentes sobre el uso del conocimiento de la gravedad de la Tierra y el tamaño de un objeto en la interacción con el entorno. A continuación, simulamos las predicciones del modelo GS, un modelo que permite predecir el tiempo de contacto a partir de una combinación de variables a priori (gravedad y tamaño de pelota) y variables ópticas. Comparamos la precisión de las predicciones del tiempo de contacto con una alternativa que solo utiliza variables ópticas, mostrando que basarse en las variables a priori de la gravedad y el tamaño de la bola resuelve la ambigüedad en la estimación del tiempo de contacto. Por último, mostramos varios escenarios en los que el modelo GS conduciría a predicciones con errores sistemáticos; escenarios que pondremos a prueba en los siguientes estudios. En el tercer estudio, creamos trayectorias para las que el modelo GS da predicciones precisas del tiempo hasta el contacto en diferentes tiempos de vuelo, pero proporciona diferentes errores sistemáticos en cualquier otro momento. Hipotetizamos que, si la visibilidad de la pelota está restringida a una ventana de tiempo corta, los participantes preferirían ver la pelota durante las ventanas de tiempo en las que las predicciones del modelo son precisas. Nuestros resultados mostraron que los observadores preferían utilizar un tiempo de visualización de la pelota relativamente constante. Por otra parte, mostramos pruebas de que la dirección de los errores cometidos por los participantes para las diferentes trayectorias probadas se correspondía con la dirección predicha por el modelo GS. En el cuarto y último estudio, investigamos el papel del conocimiento a priori de la aceleración gravitatoria de la Tierra y del tamaño de la pelota en la estimación del tiempo de vuelo y la dirección de movimiento de un observador hacia el punto de interceptación. Introdujimos a nuestros participantes en un entorno en el que tanto la aceleración gravitatoria como el tamaño de la pelota se asignaban aleatoriamente ensayo a ensayo. La tarea de los observadores consistía en desplazarse hacia el punto de interceptación y predecir el tiempo de vuelo restante tras una breve oclusión. Nuestros resultados proporcionan pruebas del uso del conocimiento previo de la gravedad y el tamaño de la pelota para estimar el tiempo de contacto. También encontramos pruebas de que la aceleración gravitatoria puede desempeñar un papel en la orientación de la locomoción hacia el punto de intercepción. En resumen, en esta tesis contribuimos a responder a una cuestión fundamental en la Percepción: como interpretamos la información para actuar en el mundo. Para ello, mostramos evidencias de que los humanos aplican sus conocimientos sobre regularidades del entorno en forma de conocimiento a priori de la aceleración gravitatoria de la tierra, del tamaño de la pelota o de la estabilidad del mundo a nuestro alrededor para interpretar la información visual

Gravity and known size calibrate visual information to time parabolic trajectories

Catching a ball in a parabolic flight is a complex task in which the time and area of interception are strongly coupled, making interception possible for a short period. Although this makes the estimation of time-to-contact (TTC) from visual information in parabolic trajectories very useful, previous attempts to explain our precision in interceptive tasks circumvent the need to estimate TTC to guide our action. Obtaining TTC from optical variables alone in parabolic trajectories would imply very complex transformations from 2D retinal images to a 3D layout. We propose based on previous work and show by using simulations that exploiting prior distributions of gravity and known physical size makes these transformations much simpler, enabling predictive capacities from minimal early visual information. Optical information is inherently ambiguous, and therefore, it is necessary to explain how these prior distributions generate predictions. Here is where the role of prior information comes into play: it could help to interpret and calibrate visual information to yield meaningful predictions of the remaining TTC. The objective of this work is: (1) to describe the primary sources of information available to the observer in parabolic trajectories; (2) unveil how prior information can be used to disambiguate the sources of visual information within a Bayesian encoding-decoding framework; (3) show that such predictions might be robust against complex dynamic environments; and (4) indicate future lines of research to scrutinize the role of prior knowledge calibrating visual information and prediction for action control

Trajectory Modeling, Estimation and Interception of a Thrown Ball using a Robotic Ground Vehicle

abstract: Toward the ambitious long-term goal of developing a robotic circus, this thesis addresses key steps toward the development of a ground robot that can catch a ball. Toward this end, we examine nonlinear quadratic drag trajectories for a tossed ball. Relevant least square error fits are provided. It is also shown how a Kalman filter and Extended Kalman filter can be used to generate estimates for the ball trajectory. Several simple ball intercept policies are examined. This includes open loop and closed loop policies. It is also shown how a low-cost differential-drive research grade robot can be built, modeled and controlled. Directions for developing more complex xy planar intercept policies are also briefly discussed. In short, the thesis establishes a foundation for future work on developing a practical ball catching robot.Dissertation/ThesisMasters Thesis Mechanical Engineering 201

A Neural Circuit Model for Prospective Control of Interceptive Reaching

Two prospective controllers of hand movements in catching -- both based on required velocity control -- were simulated. Under certain conditions, this required velocity controlled to overshoots of the future interception point. These overshoots were absent in pertinent experiments. To remedy this shortcoming, the required velocity model was reformulated in terms of a neural network, the Vector Integration To Endpoint model, to create a Required Velocity Integration To Endpoint modeL Addition of a parallel relative velocity channel, resulting in the Relative and Required Velocity Integration To Endpoint model, provided a better account for the experimentally observed kinematics than the existing, purely behavioral models. Simulations of reaching to intercept decelerating and accelerating objects in the presence of background motion were performed to make distinct predictions for future experiments.Vrije Universiteit (Gerrit-Jan van Jngen-Schenau stipend of the Faculty of Human Movement Sciences); Royal Netherlands Academy of Arts and Sciences; Defense Advanced Research Projects Agency and Office of Naval Research (N00014-95-1-0409

Cognitive Psychology in Crisis: Ameliorating the Shortcomings of Representationalism

Traditional cognitive psychology relies on concepts bordering idealism, an issue that has been known since the end of the 19th century. At best, the underlying assumptions are misleading and do not bring us closer to an understanding of human enterprise. Also, psychology in general is not a unified paradigm; its sub-disciplines rely on different conceptual bases. Ecological Psychology can change that. Getting rid of the non-sequitur “it is all in the brain” is a start and not that controversial, but, this is simply a stepping stone to a complete change in perspective. Organisms are born into an ever-changing environment, which they constantly interact with, perceive themselves in, constantly change and are changed by. An attempt is made to contrast computational and ecological assumptions about how the brain works by having participants intercept an object on a computer screen. Hypothesis is that participants will favour an ecological strategy over a computational. Results speak in favour of reliance on ecological assumptions rather than computational and also indicates that representations may not be necessary even for objects that are temporarily imperceptible

Interaction between different sources of situational probability information to anticipate the bowler’s intention in cricket

In elite fastball sports, such as cricket, performance occurs at the limit of human capability as the time constraints of perceiving and acting are severe. Cricket batsmen are therefore required to use the two sources of advanced information (kinematic cues and situational probability) to anticipate an upcoming delivery to negate the effects of the time constraints. The source of information that will be focused on in this study will be situational probability, with the aim being to determine the interaction between bowling sequence and field placement as sources of situational probability used by skilled cricket batsmen to predict a bowler’s intention. Four different conditions were created according to the situational probability information presented to the batsmen, namely no sources, sequence alone, field placement alone, and both sources. Fifteen skilled cricket batsmen were required to face deliveries projected by a bowling machine and make predictions as to where the next delivery outcome was going to pitch based on perceived situational probability information and attempt to make successful bat-ball contact. In order to compare the use and importance of the four conditions of situational probability information,prediction accuracy, response accuracy and the initial movement time of the batsmen were recorded and analysed. Results of the study revealed no significant difference between conditions of situational probability presented to batsmen for prediction accuracy, response accuracy, and initial movement time. However, significant differences were found between categories of congruence for prediction accuracy results. The prediction accuracy results reveal that batsmen equally value each source of situational probability information and that when sources were presented in conjunction with each other, no enhancement in anticipatory performance or interception of the cricket ball occurred.The results of the current study suggest that it is not necessarily the number of sources present, but rather the relevance of the source that is most important for a batsman to predict the outcome of a delivery. The prediction accuracy of batsmen is dependent on the nature of the information presented rather than the amount of information presented. Performers draw upon more pertinent information variables according to the relevance to the task at hand.The response accuracy results reveal that the batsmen have the required action capabilities to make successful bat-ball contact regardless of whether or not they correctly anticipate the upcoming delivery’s landing position

Design of a Specialized UAV Platform for the Discharge of a Fire Extinguishing Capsule

Tato práce se zabývá návrhem systému specializovaného pro autonomní detekci a lokalizaci požárů z palubních senzorů bezpilotních helikoptér. Hašení požárů je zajištěno automatickým vystřelením ampule s hasící kapalinou do zdroje požáru z palubního vystřelovače. Hlavní část této práce se soustředí na detekci požárů v datech termální kamery a jejich následnou lokalizaci ve světě za pomoci palubní hloubkové kamery. Bezpilotní helikoptéra je poté optimálně navigována na pozici pro zajištění průletu ampule s hasící kapalinou do zdroje požáru. Vyvinuté metody jsou detailně analyzovány a jejich chování je testováno jak v simulaci, tak současně i při reálných experimentech. Kvalitativní a kvantitativní analýza ukazuje na použitelnost a robustnost celého systému.This thesis deals with the design of an unmanned multirotor aircraft system specialized for autonomous detection and localization of fires from onboard sensors, and the task of fast and effective fire extinguishment. The main part of this thesis focuses on the detection of fires in thermal images and their localization in the world using an onboard depth camera. The localized fires are used to optimally position the unmanned aircraft in order to effectively discharge an ampoule filled with a fire extinguishant from an onboard launcher. The developed methods are analyzed in detail and their performance is evaluated in simulation scenarios as well as in real-world experiments. The included quantitative and qualitative analysis verifies the feasibility and robustness of the system

(De)synchronization of advanced visual information and ball flight characteristics constrains emergent information–movement couplings during one-handed catching

Advance visual information of a projection action and ball flight information is important for organizing dynamic interceptive actions like catching. However, how the central nervous system (CNS) manages the relationship between advance visual information and emerging ball flight information in regulating behavior is less well understood. Here, we sought to examine the extent that advance visual information to the CNS constrains regulation of catching actions by synchronizing and desynchronizing its relationship with ball trajectory characteristics. Novel technology was used to present video footage of an actor throwing a ball at three different speeds, integrated with information from a real ball projected by a machine set to the three speeds. The technology enabled three synchronized and six desynchronized conditions between advance visual information and subsequent ball flight trajectories. Catching performance, kinematic data from the catching hand and gaze behaviors were recorded. Findings revealed that desynchronization of video images of ball projection shaped emergent catching behaviors. Footage of slower throws, paired with faster ball projection speeds, caused catching performance decrements. Timing in early phases of action was organized by the CNS to match the advance visual information presented. In later phases, like the grasp, ball flight information constraints adapted and regulated behaviors. Gaze behaviors showed increased ball projection speed resulted in participants tracking the ball for a smaller percentage of ball flight. Findings highlighted the role of the two visual systems in perception and action, implicating the importance of coupling advanced visual information and ball flight to regulate emergent movement coordination tendencies during interceptive behaviors