  Diversity-based approaches have recently gained popularity as an alternative
paradigm to performance-based policy search. A popular approach from this
family, Quality-Diversity (QD), maintains a collection of high-performing
policies separated in the diversity-metric space, defined based on policies'
rollout behaviours. When policies are parameterised as neural networks, i.e.
Neuroevolution, QD tends to not scale well with parameter space dimensionality.
Our hypothesis is that there exists a low-dimensional manifold embedded in the
policy parameter space, containing a high density of diverse and feasible
policies. We propose a novel approach to diversity-based policy search via
Neuroevolution, that leverages learned latent representations of the policy
parameters which capture the local structure of the data. Our approach
iteratively collects policies according to the QD framework, in order to (i)
build a collection of diverse policies, (ii) use it to learn a latent
representation of the policy parameters, (iii) perform policy search in the
learned latent space. We use the Jacobian of the inverse transformation
(i.e.reconstruction function) to guide the search in the latent space. This
ensures that the generated samples remain in the high-density regions of the
original space, after reconstruction. We evaluate our contributions on three
continuous control tasks in simulated environments, and compare to
diversity-based baselines. The findings suggest that our approach yields a more
efficient and robust policy search process.
