47 research outputs found
Exploring Robot Morphology Spaces through Breadth-First Search and Random Query
Evolutionary robotics offers a powerful framework for designing and evolving
robot morphologies, particularly in the context of modular robots. However, the
role of query mechanisms during the genotype-to-phenotype mapping process has
been largely overlooked. This research addresses this gap by conducting a
comparative analysis of query mechanisms in the brain-body co-evolution of
modular robots. Using two different query mechanisms, Breadth-First Search
(BFS) and Random Query, within the context of evolving robot morphologies using
CPPNs and robot controllers using tensors, and testing them in two evolutionary
frameworks, Lamarckian and Darwinian systems, this study investigates their
influence on evolutionary outcomes and performance. The findings demonstrate
the impact of the two query mechanisms on the evolution and performance of
modular robot bodies, including morphological intelligence, diversity, and
morphological traits. This study suggests that BFS is both more effective and
efficient in producing highly performing robots. It also reveals that
initially, robot diversity was higher with BFS compared to Random Query, but in
the Lamarckian system, it declines faster, converging to superior designs,
while in the Darwinian system, BFS led to higher end-process diversity.Comment: arXiv admin note: text overlap with arXiv:2303.12594. substantial
text overlap with arXiv:2309.1309
Lamarck's Revenge: Inheritance of Learned Traits Can Make Robot Evolution Better
Evolutionary robot systems offer two principal advantages: an advanced way of
developing robots through evolutionary optimization and a special research
platform to conduct what-if experiments regarding questions about evolution.
Our study sits at the intersection of these. We investigate the question ``What
if the 18th-century biologist Lamarck was not completely wrong and individual
traits learned during a lifetime could be passed on to offspring through
inheritance?'' We research this issue through simulations with an evolutionary
robot framework where morphologies (bodies) and controllers (brains) of robots
are evolvable and robots also can improve their controllers through learning
during their lifetime. Within this framework, we compare a Lamarckian system,
where learned bits of the brain are inheritable, with a Darwinian system, where
they are not. Analyzing simulations based on these systems, we obtain new
insights about Lamarckian evolution dynamics and the interaction between
evolution and learning. Specifically, we show that Lamarckism amplifies the
emergence of `morphological intelligence', the ability of a given robot body to
acquire a good brain by learning, and identify the source of this success:
`newborn' robots have a higher fitness because their inherited brains match
their bodies better than those in a Darwinian system.Comment: preprint-nature scientific report. arXiv admin note: text overlap
with arXiv:2303.1259
A Comparative Study of Brain Reproduction Methods for Morphologically Evolving Robots
In the most extensive robot evolution systems, both the bodies and the brains
of the robots undergo evolution and the brains of 'infant' robots are also
optimized by a learning process immediately after 'birth'. This paper is
concerned with the brain evolution mechanism in such a system. In particular,
we compare four options obtained by combining asexual or sexual brain
reproduction with Darwinian or Lamarckian evolution mechanisms. We conduct
experiments in simulation with a system of evolvable modular robots on two
different tasks. The results show that sexual reproduction of the robots'
brains is preferable in the Darwinian framework, but the effect is the opposite
in the Lamarckian system (both using the same infant learning method). Our
experiments suggest that the overall best option is asexual reproduction
combined with the Lamarckian framework, as it obtains better robots in terms of
fitness than the other three. Considering the evolved morphologies, the
different brain reproduction methods do not lead to differences. This result
indicates that the morphology of the robot is mainly determined by the task and
the environment, not by the brain reproduction methods.Comment: 8 pages, ALif
Acquiring moving skills in robots with evolvable morphologies: Recent results and outlook
© 2017 ACM. We construct and investigate a strongly embodied evolutionary system, where not only the controllers but also the morphologies undergo evolution in an on-line fashion. In these studies, we have been using various types of robot morphologies and controller architectures in combination with several learning algorithms, e.g. evolutionary algorithms, reinforcement learning, simulated annealing, and HyperNEAT. This hands-on experience provides insights and helps us elaborate on interesting research directions for future development
Lamarckian Evolution of Simulated Modular Robots
We study evolutionary robot systems where not only the robot brains but also the robot bodies are evolvable. Such systems need to include a learning period right after ‘birth' to acquire a controller that fits the newly created body. In this paper we investigate the possibility of bootstrapping infant robot learning through employing Lamarckian inheritance of parental controllers. In our system controllers are encoded by a combination of a morphology dependent component, a Central Pattern Generator (CPG), and a morphology independent part, a Compositional Pattern Producing Network (CPPN). This makes it possible to transfer the CPPN part of controllers between different morphologies and to create a Lamarckian system. We conduct experiments with simulated modular robots whose fitness is determined by the speed of locomotion, establish the benefits of inheriting optimized parental controllers, shed light on the conditions that influence these benefits, and observe that changing the way controllers are evolved also impacts the evolved morphologies
How the Morphology Encoding Influences the Learning Ability in Body-Brain Co-Optimization
Embedding the learning of controllers within the evolution of morphologies has emerged as an effective strategy for the co-optimization of agents' bodies and brains. Intuitively, that is how nature shaped animal life on Earth. Still, the design of such co-optimization is a complex endeavor; one issue is the choice of the genetic encoding for the morphology. Such choice can be crucial for the effectiveness of learning, i.e., how fast and to what degree agents adapt, through learning, during their life. Here we evolve the morphologies of voxel-based soft agents with two different encodings, direct and indirect while learning the controllers with reinforcement learning. We experiment with three tasks, ranging from cave crawling to beam toppling, and study how the encoding influences the learning outcome. Our results show that the direct encoding corresponds to increased ability to learn, mostly in terms of learning speed. The same is not always true for the indirect one. We link these results to different shades of the Baldwin effect, consisting of morphologies being selected for increasing an agent’s ability to learn during its lifetime
A Comparative Analysis of Darwinian Asexual and Sexual Reproduction in Evolutionary Robotics
Evolutionary Robotics systems draw inspiration from natural evolution to solve the problem of robot design. A key moment in the evolutionary process is reproduction, when the genotype of one or more parents is inherited by their offspring. Existent approaches have used both sexual and asexual reproduction but a comparison between the two is still missing. In this work, we study the effects of sexual and asexual reproduction on the controllers of an Evolutionary Robotics system. In our system, both morphologies and controllers are jointly evolved to solve two separate tasks. We adopt the Triangle of Life framework, in which the controllers go through a phase of learning before reproduction. Using extensive simulations we show that sexual reproduction of the robots' brains is preferable over asexual reproduction as it obtains better robots in terms of fitness. Moreover, we show that sexually reproducing robots present different morphologies and behaviors than the asexually reproducing ones, even though the reproduction mechanism only affects their brains. Finally, we study the effects of the reproduction mechanism on the robots' learning capabilities. By measuring the difference between the inherited and the learned brain we find that robots that evolved using sexual reproduction have better inherited brains and are also better learners