  Parameter tuning for robotic systems is a time-consuming and challenging task
that often relies on domain expertise of the human operator. Moreover, existing
learning methods are not well suited for parameter tuning for many reasons
including: the absence of a clear numerical metric for `good robotic behavior';
limited data due to the reliance on real-world experimental data; and the large
search space of parameter combinations. In this work, we present an open-source
MATLAB Preference Optimization and Learning Algorithms for Robotics toolbox
(POLAR) for systematically exploring high-dimensional parameter spaces using
human-in-the-loop preference-based learning. This aim of this toolbox is to
systematically and efficiently accomplish one of two objectives: 1) to optimize
robotic behaviors for human operator preference; 2) to learn the operator's
underlying preference landscape to better understand the relationship between
adjustable parameters and operator preference. The POLAR toolbox achieves these
objectives using only subjective feedback mechanisms (pairwise preferences,
coactive feedback, and ordinal labels) to infer a Bayesian posterior over the
underlying reward function dictating the user's preferences. We demonstrate the
performance of the toolbox in simulation and present various applications of
human-in-the-loop preference-based learning.
