Environmental Regulation Using Plasticoding for the Evolution of Robots

Abstract

Evolutionary robot systems are usually affected by the properties of the environment indirectly through selection. In this paper, we present and investigate a system where the environment also has a direct effect—through regulation. We propose a novel robot encoding method where a genotype encodes multiple possible phenotypes, and the incarnation of a robot depends on the environmental conditions taking place in a determined moment of its life. This means that the morphology, controller, and behavior of a robot can change according to the environment. Importantly, this process of development can happen at any moment of a robot's lifetime, according to its experienced environmental stimuli. We provide an empirical proof-of-concept, and the analysis of the experimental results shows that environmental regulation improves adaptation (task performance) while leading to different evolved morphologies, controllers, and behavior.

The Impact of Early-death on Phenotypically Plastic Robots that Evolve in Changing Environments

“…Thirdly, the mechanism of plasticity is not perfect: sometimes robots look almost the same in both seasons (Fig. 7), and as shown previously, robots evolved with this plasticity capacity tend to be less fit than those evolved in each season separately (Miras et al, 2020a). The relation between these three reasons is that perhaps a genetic pool biased to one season would not be a problem if the portions of genetic material that code for the other season were optimally delineated by the mechanism of regulation.…”

“…Furthermore, the genotype encodes regulatory clauses that allow phenotypic plasticity -through these clauses, robots can develop different morphologies and controllers depending on environmental conditions. This particular encoding, decoding, and regulatory design were proposed by (Miras et al, 2020a), where more details about them and their variation operators can be found. In summary, each genotype is a distinct grammar, making use of the same alphabet.…”

“…A recent study that forms the starting point for this paper not only investigates the effects of the environment on evolved morphologies, controllers, and behaviors, but also proposes an environmental regulation mechanism that endows robots with phenotypic plasticity (Miras et al, 2020a). Phenotypic plasticity 1 means that robots can go through a developmental process and change their bodies (morphologies) and brains (controllers) during their lifetime according to the actual environmental conditions.…”

“…Phenotypic plasticity 1 means that robots can go through a developmental process and change their bodies (morphologies) and brains (controllers) during their lifetime according to the actual environmental conditions. The experiments in (Miras et al, 2020a) feature two seasons with different environmental conditions. Each robot is born in one particular season and develops a particular morphology, controller, and behavior adequate for that season.…”

“…The main objective of this paper is to revisit the study published in (Miras et al, 2020a) and investigate phenotypic plasticity in an evolving robot system that does not rely on the above assumption. In particular, we aim to answer the following research questions:…”