New Reinforcement Learning Using a Chaotic Neural Network for Emergence of "Thinking" - "Exploration" Grows into "Thinking" through Learning -

Abstract

Expectation for the emergence of higher functions is getting larger in the framework of end-to-end reinforcement learning using a recurrent neural network. However, the emergence of "thinking" that is a typical higher function is difficult to realize because "thinking" needs non fixed-point, flow-type attractors with both convergence and transition dynamics. Furthermore, in order to introduce "inspiration" or "discovery" in "thinking", not completely random but unexpected transition should be also required. By analogy to "chaotic itinerancy", we have hypothesized that "exploration" grows into "thinking" through learning by forming flow-type attractors on chaotic random-like dynamics. It is expected that if rational dynamics are learned in a chaotic neural network (ChNN), coexistence of rational state transition, inspiration-like state transition and also random-like exploration for unknown situation can be realized. Based on the above idea, we have proposed new reinforcement learning using a ChNN as an actor. The positioning of exploration is completely different from the conventional one. The chaotic dynamics inside the ChNN produces exploration factors by itself. Since external random numbers for stochastic action selection are not used, exploration factors cannot be isolated from the output. Therefore, the learning method is also completely different from the conventional one. At each non-feedback connection, one variable named causality trace takes in and maintains the input through the connection according to the change in its output. Using the trace and TD error, the weight is updated. In this paper, as the result of a recent simple task to see whether the new learning works or not, it is shown that a robot with two wheels and two visual sensors reaches a target while avoiding an obstacle after learning though there are still many rooms for improvement.