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Chapter 76 — Evolutionary Robotics

Stefano Nolfi, Josh Bongard, Phil Husbands and Dario Floreano

Evolutionary Robotics is a method for automatically generating artificial brains and morphologies of autonomous robots. This approach is useful both for investigating the design space of robotic applications and for testing scientific hypotheses of biological mechanisms and processes. In this chapter we provide an overview of methods and results of Evolutionary Robotics with robots of different shapes, dimensions, and operation features. We consider both simulated and physical robots with special consideration to the transfer between the two worlds.

Exploration and homing for battery recharge

Author  Dario Floreano

Video ID : 118

Evolved Khepera robot performing exploration and homing for battery recharge. The robot enters the recharging area approximately 2 s before full-battery discharge.

Introduction to evolutionary robotics at EPFL

Author  Dario Floreano

Video ID : 119

Method for evolving the neural network of a robot. Valid gene sequences are extracted (magnifying lens) from a binary string representing the genome of the robot. Those genes are translated into neurons of different types (colors) according to the genetic specifications, such as sensory, motor, excitatory, or inhibitory neurons. The corresponding neural network is connected to the sensors and motors of the robot and the resulting behavior of the robot is measured according to the fitness function. The genomes of the individuals that had the worst performance are discarded from the population (symbolically thrown into a dustbin) whereas the genomes of the best individuals are paired and crossed over with small random mutations to generate new offspring (the process of selective reproduction is symbolically shown to occur in a mother robot). After several generations of selective reproductions with mutations, robots display better or novel behaviors.

Evolution of visually-guided behaviour on Sussex gantry robot

Author  Phil Husbands

Video ID : 371

Behaviour evolved in the real world on the Sussex gantry robot in 1994. Controllers (evolved neural networks plus visual sampling morphology) are automatically evaluated on the actual robot. The required behaviour is a shape discrimination task: to move to the triangle, while ignoring the rectangle, under very noisy lighting conditions.

Evolved walking in octopod

Author  Phil Husbands

Video ID : 372

Evolved-walking behaviors on an octopod robot. Multiple gaits and obstacle avoidance can be observed. The behavior was evolved in a minimal simulation by Nick Jakobi at Sussex University and is successfully transferred to the real world as is evident from the video.

Evolved homing walk on rough ground

Author  Phil Husbands

Video ID : 373

Evolved, simulated hexapod walks over rough terrain while homing on a beacon. This behavior was incrementally evolved with the controlling neural-network architecture which was expanding at each stage. Work done at Sussex University by Eric Vaughan.

Evolved bipedal walking

Author  Phil Husbands

Video ID : 374

The video shows stages of evolution of bipedal walking in a simulated, bipedal robot using realistic physics (from the work by Torsten Reil and originating at Sussex University). This was the first example of successfully- evolved bipedal gaits produced in a physics-engine-based simulation. The problem is inherently dynamically unstable, thus making it an interesting challenge.

Evolved GasNet visualisation

Author  Phil Husbands

Video ID : 375

The video shows a successfully evolved GasNet controlling a simulated robot engaged in a visual-discrimination task under noisy lighting. The GasNet architecture and all node properties are evolved along with the visual sampling morphology (parts of the visual field used as inputs to the GasNet). A minimal simulation is used which allows transfer to the real robot (see Sussex gantry Video 371). A highly minimal controller and visual morphology have evolved. The system is highly robust, coping with very noisy conditions. As can be seen, the GasNet employs multiple oscillator subcircuits - partly to filter out noise. Work by Tom Smith and Phil Husbands.

Evolved group coordination

Author  Phil Husbands

Video ID : 376

Identical evolved robots are required to coordinate by coming together and moving off in the same direction. No roles are pre-assigned. The robots must evolve to coordinate such that one robot takes on the role of leader and the others follow. Only minimal sensing is available (proximity IR sensing) and no dedicated communication channels. The robot neural-network controllers are evolved using a minimal simualtion and, as can be seen, these successfully transfer to reality. Work by Matt Quinn, Giles Mayley, Linc Smith and Phil Husbands at Sussex University.

Morphological change in an autonomous robot.

Author  Josh Bongard

Video ID : 771

This video demonstrates a robot that is able to change its morphology. It is here shown that this change enables evolution to create useful controllers for this robot faster than a comparable robot that does not undergo morphological change.

More complex robots evolve in more complex environments

Author  Josh Bongard

Video ID : 772

This set of videos demonstrates that complex environments influence the evolution of robots with more complex body plans.