IV-Posterior: Inverse Value Estimation for Interpretable Policy Certificates
This work provides a method for robot skill and policy deployment to improve reliability and interpretability by identifying environmental conditions where a policy is effective, which is an incremental improvement for RL practitioners.
This paper addresses the problem of policy interpretability in model-free reinforcement learning by proposing IV-Posterior, a method to identify the inductive biases or idealised operating conditions of pre-trained policies. By fitting distributions over environmental parameters where a policy is effective, IV-Posterior enables substantial performance gains when this knowledge guides policy selection.
Model-free reinforcement learning (RL) is a powerful tool to learn a broad range of robot skills and policies. However, a lack of policy interpretability can inhibit their successful deployment in downstream applications, particularly when differences in environmental conditions may result in unpredictable behaviour or generalisation failures. As a result, there has been a growing emphasis in machine learning around the inclusion of stronger inductive biases in models to improve generalisation. This paper proposes an alternative strategy, inverse value estimation for interpretable policy certificates (IV-Posterior), which seeks to identify the inductive biases or idealised conditions of operation already held by pre-trained policies, and then use this information to guide their deployment. IV-Posterior uses MaskedAutoregressive Flows to fit distributions over the set of conditions or environmental parameters in which a policy is likely to be effective. This distribution can then be used as a policy certificate in downstream applications. We illustrate the use of IV-Posterior across a two environments, and show that substantial performance gains can be obtained when policy selection incorporates knowledge of the inductive biases that these policies hold.