PackIt: A Virtual Environment for Geometric Planning

The ability to jointly understand the geometry of objects and plan actions for manipulating them is crucial for intelligent agents. We refer to this ability as geometric planning. Recently, many interactive environments have been proposed to evaluate intelligent agents on various skills, however, none of them cater to the needs of geometric planning. We present PackIt, a virtual environment to evaluate and potentially learn the ability to do geometric planning, where an agent needs to take a sequence of actions to pack a set of objects into a box with limited space. We also construct a set of challenging packing tasks using an evolutionary algorithm. Further, we study various baselines for the task that include model-free learning-based and heuristic-based methods, as well as search-based optimization methods that assume access to the model of the environment. Code and data are available at https://github.com/princeton-vl/PackIt.Comment: Accepted to ICML 202

SOFT HYDROGEL BATTERIES: THE DANIELL CELL CONCEPTUALIZED IN HYBRID HYDROGELS

Energy storage devices such as batteries are important elements in many electronic devices. Currently, researchers are seeking to create new electronic devices that are "soft", i.e., bendable and stretchable. However, the batteries that power such devices are still mostly hard structures. In the current thesis, we have attempted to develop a "soft" battery out of hydrogels. Specifically, we have made a soft version of the Daniell Cell, which is a classic electrochemical cell. Our design involves a hybrid gel composed of three distinct layers. The top and bottom layers are gels swollen with a zinc salt and a copper salt, respectively, while the middle layer is akin to a "salt bridge" between the two. The hybrid gel is made by a polymerization technique developed in our laboratory and it retains good mechanical integrity (i.e., the individual layers do not delaminate). Zinc and copper foils are then attached to the hydrogel, thus creating an overall battery, and its discharge performance is reported. One unique aspect of these gel batteries is that they can be dehydrated and stored in a dry form, whereupon they are no longer batteries. In this inactive state, the materials are safe and light to transport. Upon rehydration, the gels revert to being functional batteries. This concept could be useful for military or other applications where an emergency energy storage is needed

Online Learning and Planning of Dynamical Systems Using Gaussian Processes

Master'sMASTER OF SCIENC

Modelling the Pedestrian Speed at Signalised Intersection Crosswalks for Heterogeneous Traffic Conditions

Pedestrian crossing speed is the key element in the design of pedestrian facilities. It depends on various attributes related to road, traffic and pedestrians. In this paper, an attempt has been made to explore the variation, examine the influencing factors and formulate a model for the pedestrian crossing speed at signalised intersection crosswalks. The data have been collected using video graphic technique at 16 signalised crosswalks of the Chandigarh city. The findings reveal that a 15th percentile crossing speed (1.11-1.31 m/s) exceeds the design crossing speed of 0.95 m/s. It is also higher than the crossing speed of 1.2 m/s, usually being prescribed and adopted in the developed countries. The statistical analysis indicates no significant difference in the percentile crossing speeds between males and females. However, the variation exists among different age groups, group sizes, and crossing patterns. The correlation analysis depicts that the pedestrian crossing speed has significant negative correlation with the crosswalk width, the crosswalk length, the width of the pedestrian island, the classification of road, average traffic flow and average pedestrian delay, whereas the availability of separate bicycle paths at intersections is positively correlated. Furthermore, the stepwise regression model with 70.1 percent accuracy reveals that the crosswalk width, the width of the pedestrian island and the average pedestrian delay play a predominant role in determining the pedestrian crossing speed. The authors propose the usage of the developed model for setting out the standards for the appropriate design crossing speed for different crosswalks having similar geometric and traffic conditions as that of the study area.</p

Pedestrian Safety on Crosswalks in India - Need of the Hour

A paradigm shift has been observed from ‘moving of vehicles’ to ‘moving of persons’ while planning for transportation facilities in cities. Provision of integrated and barrier free pedestrian facilities is essential to ensure inclusive mobility. Pedestrian facilities are a critical component in producing a pedestrianfriendly environment. In India, the present facilities provided for the pedestrians are not efficient in general and crosswalks (zebra crossings) in particular. The pedestrian casualties in India have registered an increase of 11.7 percent in the year 2017, of which 31 percent have occurred on crosswalks. Therefore, an attempt has been made to overview the level of safety provided on the crosswalks. It has been found that majority of crosswalks are not fulfilling their intended purposes due to improper signage and markings, inadequate maintenance and bad surface condition. Another significant reason hampering the safety of pedestrians at crosswalks has been found to be inappropriate provision of guardrails and pedestrian refuge islands. Hence, some measures have been suggested to augment the pedestrian safety on the crosswalks

Rel3D: A Minimally Contrastive Benchmark for Grounding Spatial Relations in 3D

Understanding spatial relations (e.g., "laptop on table") in visual input is important for both humans and robots. Existing datasets are insufficient as they lack large-scale, high-quality 3D ground truth information, which is critical for learning spatial relations. In this paper, we fill this gap by constructing Rel3D: the first large-scale, human-annotated dataset for grounding spatial relations in 3D. Rel3D enables quantifying the effectiveness of 3D information in predicting spatial relations on large-scale human data. Moreover, we propose minimally contrastive data collection -- a novel crowdsourcing method for reducing dataset bias. The 3D scenes in our dataset come in minimally contrastive pairs: two scenes in a pair are almost identical, but a spatial relation holds in one and fails in the other. We empirically validate that minimally contrastive examples can diagnose issues with current relation detection models as well as lead to sample-efficient training. Code and data are available at https://github.com/princeton-vl/Rel3D.Comment: Accepted to NeurIPS 202

A multimodal mixture-of-experts model for dynamic emotion prediction in movies

This paper addresses the problem of continuous emotion prediction in movies from multimodal cues. The rich emotion content in movies is inherently multimodal, where emotion is evoked through both audio (music, speech) and video modalities. To capture such affective information, we put forth a set of audio and video features that includes several novel features such as, Video Compressibility and Histogram of Facial Area (HFA). We propose a Mixture of Experts (MoE)-based fusion model that dynamically combines information from the audio and video modalities for predicting the emotion evoked in movies. A learning module, based on hard Expectation-Maximization (EM) algorithm, is presented for the MoE model. Experiments on a database of popular movies demonstrate that our MoE-based fusion method outperforms popular fusion strategies (e.g. early and late fusion) in the context of dynamic emotion prediction