Reflexes kick in and adjust the movement patterns to keep the animal from falling. A small bump on the ground, however, changes the walk. Furthermore, reflexes are involuntary motor control actions triggered by hard-coded neural pathways that connect sensors in the leg with the spinal cord.Īs long as the young animal walks over a perfectly flat surface, CPGs can be sufficient to control the movement signals from the spinal cord.
Central pattern generator networks aid the generation of rhythmic tasks such as walking, blinking or digestion. In humans and animals, these central pattern generators are networks of neurons in the spinal cord that produce periodic muscle contractions without input from the brain. The learning algorithm adapts control parameters of a Central Pattern Generator (CPG). The robot learns to walk by continuously comparing sent and expected sensor information, running reflex loops, and adapting its motor control patterns. A Bayesian optimization algorithm guides the learning: the measured foot sensor information is matched with target data from the modeled virtual spinal cord running as a program in the robot's computer. Learning algorithm optimizes virtual spinal cordĪfter learning to walk in just one hour, Ruppert's robot makes good use of its complex leg mechanics. But if it stumbles frequently, it gives us a measure of how well the robot walks."įelix Ruppert is first author of " Learning Plastic Matching of Robot Dynamics in Closed-loop Central Pattern Generators," which will be published Jin the journal Nature Machine Intelligence. "If an animal stumbles, is that a mistake? Not if it happens once.
"As engineers and roboticists, we sought the answer by building a robot that features reflexes just like an animal and learns from mistakes," says Felix Ruppert, a former doctoral student in the Dynamic Locomotion research group at MPI-IS. They built a four-legged, dog-sized robot, that helped them figure out the details.
Researchers at the Max Planck Institute for Intelligent Systems (MPI-IS) in Stuttgart conducted a research study to find out how animals learn to walk and learn from stumbling.