61 research outputs found
Synthesis Study on Employing Snowplow Driving Simulators in Training
Departments of Transportation (DOTs) need to mobilize workers under harsh weather conditions for winter operations. Traditional snowplow driver training at INDOT is usually conducted annually before the snow season; therefore, it does not replicate the conditions which drivers will be exposed to during winter operations. To this point, some state DOTs have incorporated simulators in their snowplow driver training. Despite this raised interest, few studies have (1) surveyed other state DOTs about the use of this equipment in winter operations driver training, or (2) provided a systematic consideration of all factors involved in the decision to use driving simulators in snowplow driver training. To fill these gaps, the present study synthesizes information from previous literature, revises current information from INDOT, and surveys other state DOTs to identify the benefits and challenges of driving simulators for snowplow driver training. A mixed methods approach was utilized including a review of current INDOT practices, interviews with stakeholders, a survey of other state DOTs, and results from a pilot training. Based on the findings, the researchers recommend that INDOT continues to explore the use of driving simulators for training purposes in addition to the yearly snowplow driver training, due the ability to reinforce learning in a safe environment. Moreover, the research team suggests the following areas for further research: evaluating optimal simulator “seat time,” peer learning in simulator training, and the impact of experience level and work assignment in the perception of driving simulator training effectiveness
DCL: Differential Contrastive Learning for Geometry-Aware Depth Synthesis
We describe a method for unpaired realistic depth synthesis that learns
diverse variations from the real-world depth scans and ensures geometric
consistency between the synthetic and synthesized depth. The synthesized
realistic depth can then be used to train task-specific networks facilitating
label transfer from the synthetic domain. Unlike existing image synthesis
pipelines, where geometries are mostly ignored, we treat geometries carried by
the depth scans based on their own existence. We propose differential
contrastive learning that explicitly enforces the underlying geometric
properties to be invariant regarding the real variations been learned. The
resulting depth synthesis method is task-agnostic, and we demonstrate the
effectiveness of the proposed synthesis method by extensive evaluations on
real-world geometric reasoning tasks. The networks trained with the depth
synthesized by our method consistently achieve better performance across a wide
range of tasks than state of the art, and can even surpass the networks
supervised with full real-world annotations when slightly fine-tuned, showing
good transferability.Comment: Accepted by International Conference on Robotics and Automation
(ICRA) 2022 and RA-L 202
Game-Theoretic Robust Reinforcement Learning Handles Temporally-Coupled Perturbations
Robust reinforcement learning (RL) seeks to train policies that can perform
well under environment perturbations or adversarial attacks. Existing
approaches typically assume that the space of possible perturbations remains
the same across timesteps. However, in many settings, the space of possible
perturbations at a given timestep depends on past perturbations. We formally
introduce temporally-coupled perturbations, presenting a novel challenge for
existing robust RL methods. To tackle this challenge, we propose GRAD, a novel
game-theoretic approach that treats the temporally-coupled robust RL problem as
a partially-observable two-player zero-sum game. By finding an approximate
equilibrium in this game, GRAD ensures the agent's robustness against
temporally-coupled perturbations. Empirical experiments on a variety of
continuous control tasks demonstrate that our proposed approach exhibits
significant robustness advantages compared to baselines against both standard
and temporally-coupled attacks, in both state and action spaces
TACO: Temporal Latent Action-Driven Contrastive Loss for Visual Reinforcement Learning
Despite recent progress in reinforcement learning (RL) from raw pixel data,
sample inefficiency continues to present a substantial obstacle. Prior works
have attempted to address this challenge by creating self-supervised auxiliary
tasks, aiming to enrich the agent's learned representations with
control-relevant information for future state prediction. However, these
objectives are often insufficient to learn representations that can represent
the optimal policy or value function, and they often consider tasks with small,
abstract discrete action spaces and thus overlook the importance of action
representation learning in continuous control. In this paper, we introduce
TACO: Temporal Action-driven Contrastive Learning, a simple yet powerful
temporal contrastive learning approach that facilitates the concurrent
acquisition of latent state and action representations for agents. TACO
simultaneously learns a state and an action representation by optimizing the
mutual information between representations of current states paired with action
sequences and representations of the corresponding future states.
Theoretically, TACO can be shown to learn state and action representations that
encompass sufficient information for control, thereby improving sample
efficiency. For online RL, TACO achieves 40% performance boost after one
million environment interaction steps on average across nine challenging visual
continuous control tasks from Deepmind Control Suite. In addition, we show that
TACO can also serve as a plug-and-play module adding to existing offline visual
RL methods to establish the new state-of-the-art performance for offline visual
RL across offline datasets with varying quality
GIMO: Gaze-Informed Human Motion Prediction in Context
Predicting human motion is critical for assistive robots and AR/VR
applications, where the interaction with humans needs to be safe and
comfortable. Meanwhile, an accurate prediction depends on understanding both
the scene context and human intentions. Even though many works study
scene-aware human motion prediction, the latter is largely underexplored due to
the lack of ego-centric views that disclose human intent and the limited
diversity in motion and scenes. To reduce the gap, we propose a large-scale
human motion dataset that delivers high-quality body pose sequences, scene
scans, as well as ego-centric views with eye gaze that serves as a surrogate
for inferring human intent. By employing inertial sensors for motion capture,
our data collection is not tied to specific scenes, which further boosts the
motion dynamics observed from our subjects. We perform an extensive study of
the benefits of leveraging eye gaze for ego-centric human motion prediction
with various state-of-the-art architectures. Moreover, to realize the full
potential of gaze, we propose a novel network architecture that enables
bidirectional communication between the gaze and motion branches. Our network
achieves the top performance in human motion prediction on the proposed
dataset, thanks to the intent information from the gaze and the denoised gaze
feature modulated by the motion. The proposed dataset and our network
implementation will be publicly available
Effect of Anodal Direct-Current Stimulation on Cortical Hemodynamic Responses With Laser-Speckle Contrast Imaging
Transcranial direct-current stimulation (DCS) offers a method for noninvasive neuromodulation usable in basic and clinical human neuroscience. Laser-speckle contrast imaging (LSCI), a powerful, low-cost method for obtaining images of dynamic systems, can detect regional blood-flow distributions with high spatial and temporal resolutions. Here, we used LSCI for measuring DCS-induced cerebral blood flow in real-time. Results showed that the change-rate of cerebral blood flow could reach approximately 10.1 ± 5.1% by DCS, indicating that DCS can increase cerebral blood flow and alter cortical hemodynamic responses. Thus, DCS shows potential for the clinical treatment and rehabilitation of ischemic strokes
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