Creating a Dynamic Quadrupedal Robotic Goalkeeper with Reinforcement Learning

We present a reinforcement learning (RL) framework that enables quadrupedal robots to perform soccer goalkeeping tasks in the real world. Soccer goalkeeping using quadrupeds is a challenging problem, that combines highly dynamic locomotion with precise and fast non-prehensile object (ball) manipulation. The robot needs to react to and intercept a potentially flying ball using dynamic locomotion maneuvers in a very short amount of time, usually less than one second. In this paper, we propose to address this problem using a hierarchical model-free RL framework. The first component of the framework contains multiple control policies for distinct locomotion skills, which can be used to cover different regions of the goal. Each control policy enables the robot to track random parametric end-effector trajectories while performing one specific locomotion skill, such as jump, dive, and sidestep. These skills are then utilized by the second part of the framework which is a high-level planner to determine a desired skill and end-effector trajectory in order to intercept a ball flying to different regions of the goal. We deploy the proposed framework on a Mini Cheetah quadrupedal robot and demonstrate the effectiveness of our framework for various agile interceptions of a fast-moving ball in the real world.Comment: First two authors contributed equally. Accompanying video is at https://youtu.be/iX6OgG67-Z

The interception of a corner kick from the contraints-led perspective

El comportamiento motor surge de la continua interacción entre tres limitadores (organismo, entorno y tarea), que nunca actúan de forma aislada. Este artículo estudia su efecto en el rendimiento, comportamiento motor y comportamiento visual de porteros de fútbol durante el lanzamiento de córner. 31 participantes, divididos en tres grupos en función del nivel de juego, intentaron atrapar el balón procedente del lanzamiento de córner en dos situaciones (estática y dinámica), mientras que se registraron sus movimientos oculares. Entre los resultados se observa que los expertos tienen un rendimiento más estable, mientras que los otros grupos rinden peor en la situación más difícil; que los expertos realizan un inicio más tardío de la carrera hacia el balón y un patrón motor más rápido para atraparlo; y que la información contenida en los jugadores implicados no es relevante, ya que los porteros dedican valores cercanos al 0% del tiempo total a su fijaciónMotor behavior arises from the continuous interaction between three constraints (organism, environment and task), which never act in isolation. This paper studies the effect of the constraints on the performance, motor behavior and visual search behavior of soccer goalkeepers during the corner kick. 31 participants, divided into three groups depending on the level of play, tried to catch the ball out of a corner kick in two situations (static and dynamic), while their eye movements were recorded. Among the results it is observed that the experts have a more stable performance, while the other groups perform worse in the most difficult situation; that the experts make a later start of their run up towards the ball and a faster motor pattern to catch it; and that the that the information of the players involved is not relevant, goalkeepers dedicate values close to 0% of their visual total time to themLa presente investigación se llevó a cabo mientras el primer autor y la segunda autora disfrutaban de una beca FPU (Formación del Profesorado Universitario) otorgada por el Ministerio de Educación, Cultura y Deporte del Gobierno de España

Experimental Analysis of Task Prioritization Training for a Group of University Flight Technology Students

The purpose of this study was to evaluate changes in task prioritization performance between pilots who participated in a CTM training course and those who did not. A pretest-posttest control group design with random assignment was used. Pilots enrolled in the Central Washington University Flight Technology Program flew pretest and posttest simulated flights on a Frasca FTD. During a two week period between pretest and posttest simulated flights pilots in the experimental group participated in a CTM training course and pilots in the control group did not. Comparison of pre- and posttest error rates shows the experimental group had a 54% decrease in task prioritization errors and the control group had a 9% increase in errors

The Effects of Innovative Shotgun Shooting Methods on Collegiate Shotgun Shooters

Sporting activities are classified according to movement demands and can be categorized as either dynamic or static actions. Many events exist within the discipline of “shooting sports”, and dynamic and static demands vary drastically among those events. However, consideration for differences in movement demands is frequently disregarded in shooting sports; common practice protocol encourages shooters to utilize static shooting techniques for all shooting sport events. In particular, shooting techniques for shotgun shooting, a dynamic sporting event, regularly align with rifle shooting (static activity) methods. Innovative dynamic shotgun shooting techniques have recently been developed, however, no previous studies have examined the outcomes of employing these dynamic techniques. Therefore, the current research investigated the effects of innovative shotgun shooting methods on collegiate shotgun shooters (n=38). Pre and post trap and skeet scores were collected at a certified International Shooting Sport Federation and USA Shooting competition field. Upon completion of pre-test shooting, subjects participated in an Optimum Shooting Performance (OSP) intervention that outlined innovative dynamic shooting and practice techniques. Post-test shooting scores were collected after 2-weeks of OSP practice. A paired sample t test identified statistically significant improvements for trap shooting scores (t[32] = 2.82, p = .008, 95% CI [0.431, 2.660], d = .49), skeet shooting scores (t[32] = 2.59, p = .01, 95% CI [0.436, 3.625], d = .45), and total shooting (sum score of trap and skeet tests) scores (t[32] = 3.37, p = .002, 95% CI [1.417, 5.734], d = .59). These results suggest that learning and utilizing the OSP methods significantly increased the shooting performance of college shotgun shooters

The General Motor Ability Hypothesis: An old idea revisited

While specific motor abilities have become a popular explanation for motor performance, the older, alternate notion of a general motor ability should be revisited. Current theories lack consensus, and most motor assessment tools continue to derive a single composite score to represent motor capacity. In addition, results from elegant statistical procedures such as higher order factor analyses, cluster analyses, and Item Response Theory support a more global motor ability. We propose a contemporary model of general motor ability as a unidimensional construct that is emergent and fluid over an individual’s lifespan, influenced by both biological and environmental factors. In this article, we address the implications of this model for theory, practice, assessment, and research. Based on our hypothesis and Item Response Theory, our Lifespan Motor Ability Scale can identify motor assessment tasks that are relevant and important across varied phases of lifespan development

Controlling reaching movements with predictable and unpredictable target motion in 10-year-old children and adults

We investigated interception behavior in adults and 10-year-old children. Participants had to intercept virtual targets moving on either a predictable (linear) or unpredictable (non-linear) path (with random direction changes). Targets moved at two different velocities, which varied randomly from trial to trial. Participants reached for the targets via a force-feedback device. Reaching movements for linearly moving targets in a block of linearly moving targets were compared with reaching movements for linearly moving targets in the context of non-linearly moving targets. Movement direction and maximum speed of the first sub-movement were analyzed as well as frequency of target hits and number of sub-movements. Unpredictable target motion caused faster movement speeds than predictable target motion for both children and adults. Additionally, unpredictable target motion caused children and adults to gear their initial movement direction further towards the current position of the target, while with predictable target motion, they geared their initial movement direction further ahead of the target towards an anticipated interception position. Together, these results suggest differential processing of predictable and unpredictable object behavior in an interception task, and that this differential processing is already in place in 10-year-old

Co-Evolutionary Learning for Cognitive Computer Generated Entities

In this paper, an approach is advocated to use a hybrid approach towards learning behaviour for computer generated entities (CGEs) in a serious gaming setting. Hereby, an agent equipped with cognitive model is used but this agent is enhanced with Machine Learning (ML) capabilities. This facilitates the agent to exhibit human like behaviour but avoid an expert having to define all parameters explicitly. More in particular, the ML approach utilizes co-evolution as a learning paradigm. An evaluation in the domain of one-versus-one air combat shows promising results