Alleviating the estimation bias of deep deterministic policy gradient via co-regularization

The overestimation in Deep Deterministic Policy Gradients (DDPG) caused by value approximation error may result in unstable policy training. Twin Delayed Deep Deterministic Policy Gradient (TD3) addresses the overestimation but suffers from the underestimation. In this paper, we propose a Co-Regularization based Deep Deterministic (CoD2) policy gradient method to mitigate the estimation bias. Two learners characterized by overestimated and underestimated biases are trained with Co-regularization to achieve this goal. The overestimated and underestimated values are updated conservatively in CoD2 for policy evaluation. Experimental results show that our method achieves comparable performance compared with other methods.