Dattaraj Rao

Dattaraj Rao

Contextual bandits provide an effective way to model the dynamic data problem in ML by leveraging online (incremental) learning to continuously adjust the predictions based on changing environment. We explore details on contextual bandits, an extension to the traditional reinforcement learning (RL) problem and build a novel algorithm to solve this problem using an array of action-based learners. We apply this approach to model an article recommendation system using an array of stochastic gradient descent (SGD) learners to make predictions on rewards based on actions taken. We then extend the approach to a publicly available MovieLens dataset and explore the findings. First, we make available a simplified simulated dataset showing varying user preferences over time and how this can be evaluated with static and dynamic learning algorithms. This dataset made available as part of this research is intentionally simulated with limited number of features and can be used to evaluate different problem-solving strategies. We will build a classifier using static dataset and evaluate its performance on this dataset. We show limitations of static learner due to fixed context at a point of time and how changing that context brings down the accuracy. Next we develop a novel algorithm for solving the contextual bandit problem. Similar to the linear bandits, this algorithm maps the reward as a function of context vector but uses an array of learners to capture variation between actions/arms. We develop a bandit algorithm using an array of stochastic gradient descent (SGD) learners, with separate learner per arm. Finally, we will apply this contextual bandit algorithm to predicting movie ratings over time by different users from the standard Movie Lens dataset and demonstrate the results.

S Ritika, Dattaraj Rao

Regular maintenance of all the assets is pivotal for proper functioning of railway. Manual maintenance can be very cumbersome and leave room for errors. Track anomalies like vegetation overgrowth, sun kinks affect the track construct and result in unequal load transfer, imbalanced lateral forces on tracks which causes further deterioration of tracks and can ultimately result in derailment of locomotive. Hence there is a need to continuously monitor rail track health. Track anomalies are rare with the skew as high as one anomaly in millions of good images. We propose a method to build training data that will make our algorithms more robust and help us detect real world track issues. The data augmentation will have a direct effect in making us detect better anomalies and hence improve time for railroads that is spent in manual inspection. This paper talks about a real world use case of detecting railway track defects from a camera mounted on a moving locomotive and tracking their locations. The camera is engineered to withstand the environment factors on a moving train and provide a consistent steady image at around 30 frames per second. An image simulation pipeline of track detection, region of interest selection, augmenting image for anomalies is implemented. Training images are simulated for sun kink and vegetation overgrowth. Inception V3 model pretrained on Imagenet dataset is finetuned for a 2 class classification. For the case of vegetation overgrowth, the model generalizes well on actual vegetation images, though it was trained and validated solely on simulated images which might have different distribution than the actual vegetation. Sun kink classifier can classify professionally simulated sun kink videos with a precision of 97.5%.

S Ritika, Dattaraj Rao

Train Pilot is a very tedious and stressful job. Pilots must be vigilant at all times and its easy for them to lose track of time of shift. In countries like USA the pilots are mandated by law to adhere to 8 hour shifts. If they exceed 8 hours of shift the railroads may be penalized for over-tiring their drivers. The problem happens when the 8 hour shift may end in middle of a journey. In such case, the new drivers must be moved to the location locomotive is operating for shift change. Hence accurate monitoring of drivers during their shift and making sure the shifts are scheduled correctly is very important for railroads. Here we propose an automated camera system that uses camera mounted inside Locomotive cabs to continuously record video feeds. These feeds are analyzed in real time to detect the face of driver and recognize the driver using state of the art deep Learning techniques. The outcome is an increased safety of train pilots. Cameras continuously capture video from inside the cab which is stored on an on board data acquisition device. Using advanced computer vision and deep learning techniques the videos are analyzed at regular intervals to detect presence of the pilot and identify the pilot. Using a time based analysis, it is identified for how long that shift has been active. If this time exceeds allocated shift time an alert is sent to the dispatch to adjust shift hours.