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Johannes Fischer

6 accepted papers

2024

ConstrainedZero: Chance-Constrained POMDP Planning Using Learned Probabilistic Failure Surrogates and Adaptive Safety Constraints

IJCAI 2024poster

To plan safely in uncertain environments, agents must balance utility with safety constraints. Safe planning problems can be modeled as a chance-constrained partially observable Markov decision process (CC-POMDP) and solutions often use expensive rollouts or heuristics to estimate the optimal value…

2023

SHAIL: Safety-Aware Hierarchical Adversarial Imitation Learning for Autonomous Driving in Urban Environments

ICRA 2023poster

Designing a safe and human-like decision-making system for an autonomous vehicle is a challenging task. Generative imitation learning is one possible approach for automating policy-building by leveraging both real-world and simulated decisions. Previous work that applies generative imitation learnin…

Cited by 22SourcecodeScholar
2021

Minimizing Safety Interference for Safe and Comfortable Automated Driving with Distributional Reinforcement Learning

IROS 2021poster

Despite recent advances in reinforcement learning (RL), its application in safety critical domains like autonomous vehicles is still challenging. Although penalizing RL agents for risky situations can help to learn safe policies, it may also lead to highly conservative behavior. In this paper, we pr…

Cited by 30SourceScholar
2021

Sampling-based Inverse Reinforcement Learning Algorithms with Safety Constraints

IROS 2021poster

Planning for robotic systems is frequently formulated as an optimization problem. Instead of manually tweaking the parameters of the cost function, they can be learned from human demonstrations by Inverse Reinforcement Learning (IRL). Common IRL approaches employ a maximum entropy trajectory distrib…

Cited by 16SourceScholar
2020

Information Particle Filter Tree: An Online Algorithm for POMDPs with Belief-Based Rewards on Continuous Domains

ICML 2020poster

Planning in Partially Observable Markov Decision Processes (POMDPs) inherently gathers the information necessary to act optimally under uncertainties. The framework can be extended to model pure information gathering tasks by considering belief-based rewards. This allows us to use reward shaping to…

2015

Finding line spectral frequencies using the fast fourier transform

ICASSP 2015accepted

Main-stream speech codecs are based on modelling the speech source by a linear predictor. An efficient domain for quantization and coding of this linear predictor is the line spectral frequency representation, where the predictor is encoded into an ordered set of frequencies that correspond to the r…

Cited by 0SourceScholar