Scientists have developed a controller that can generate complex gaits in a six-legged robot, allowing the automaton to mimic the movement of insects.
AsianScientist (Mar. 15, 2018) – A research group at the Tokyo Institute of Technology (Tokyo Tech), Japan, has developed a method to control the movement of multi-legged robots. They published their findings in IEEE Access.
In the natural world, many species can walk over slopes and irregular surfaces, reaching places inaccessible even to the most advanced rover robots. It remains a mystery how such complex movements are handled so seamlessly by even the tiniest creatures.
What researchers do know is that even the simplest brains contain pattern-generator circuits (CPGs), which are wired up specifically for generating walking patterns. Attempts to replicate such circuits artificially have so far had limited success, due poor flexibility.
In this study, the researchers led by Dr. Ludovico Minati at Tokyo Tech, have developed a controller for walking pattern generation capable of producing complex gaits. The biologically-inspired controller consists of two levels. At the top, it contains a CPG, responsible for controlling the overall sequence of leg movements, known as gait. At the bottom, it contains six local pattern generators (LPGs) responsible for controlling the trajectories of the individual legs.
They demonstrated the efficacy of their controller in an ant-like hexapod robot. Minati explained that insects can rapidly adapt their gait depending on a wide range of factors. Some gaits are observed frequently and are considered as canonical, but in reality, a near-infinite number of gaits are available, and different insects such as ants and cockroaches realize similar gaits in very different postures. Difficulties have been encountered when trying to condense so much complexity into artificial pattern generators.
With their controller, the authors of the study were able to achieve an extremely high level of versatility because they employed field-programmable analog arrays (FPAAs), which allow on-the-fly reconfiguration and tuning of all circuit parameters. The controller is built on years of previous research on non-linear and chaotic electronic networks which have demonstrated their ability to replicate phenomena observed in biological brains, even when wired up in very simple configurations.
“Perhaps the most exciting moment in the research was when we observed the robot exhibit phenomena and gaits which we neither designed nor expected, and we later found out that such gaits also exist in biological insects,” said Minati.
“As the controller responds gradually and embodies a biologically plausible approach to pattern generation, we think that it may be more seamless to drive compared to systems which decode discrete commands. This may have practical implications, and our lab has substantial know-how in this area,” said Dr. Natsue Yoshimura of Tokyo Tech, who is a co-author of the study.
The article can be found at: Minati et al. (2018) Versatile Locomotion Control of a Hexapod Robot Using a Hierarchical Network of Nonlinear Oscillator Circuits.