Hirotaka Hachiya
Tokyo Institute of Technology, University of Edinburgh, Wakayama University
Papers
14
Total Citations
266
H-Index
8
About
Hirotaka Hachiya is a researcher whose work spans machine learning, reinforcement learning, and robotics, with particular emphasis on developing statistically principled and computationally efficient algorithms. He has made significant contributions to conditional density estimation, introducing least-squares frameworks that go beyond traditional regression to capture multi-modal, asymmetric, and heteroscedastic distributions — work that has accumulated over 100 citations across two closely related papers. In reinforcement learning, Hachiya has tackled fundamental challenges in policy search and value function approximation, developing innovative techniques for sample reuse in policy gradient methods and EM-based policy search that reduce the prohibitive sampling costs common in continuous robot control tasks. His work on geodesic Gaussian kernels and manifold-based value function approximation demonstrates a sophisticated understanding of the geometric structure underlying real-world robotic environments, addressing discontinuities that standard Gaussian kernels fail to capture. His research also extends to robustness, exemplified by his least absolute policy iteration method for handling outliers in reward observations. More recently, Hachiya has explored deep generative approaches, applying variational autoencoders to laser-scan compression for robot self-localization. Collectively, his contributions reflect a career dedicated to bridging rigorous statistical methodology with practical robotics applications.
Research Focus
Key Achievements
Top Papers
- 1Least-Squares Conditional Density Estimation63 citations · 2010
- 2Conditional Density Estimation via Least-Squares Density Ratio Estimation44 citations · 2010
- 3Geodesic Gaussian kernels for value function approximation36 citations · 2008
- 4Efficient Sample Reuse in Policy Gradients with Parameter-Based Exploration27 citations · 2013
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- 7Efficient Sample Reuse in EM-Based Policy Search16 citations · 2009
- 8Value Function Approximation on Non-Linear Manifolds for Robot Motor Control15 citations · 2007
- 9Laser Variational Autoencoder for Map Construction and Self-Localization6 citations · 2018
- 10Least absolute policy iteration for robust value function approximation6 citations · 2009