Auke Ijspeert builds robots to study the movement of animals. In his TED Talk, A robot that runs and swims like a salamander, Ijspeert demonstrates Pleurobot and his work in biorobotics.
Ijspeert says there are four systems that control animal locomotion. The body itself acts as the framework and support for the motion. The spinal cord connects neural activity and mechanical movement. Central pattern generators take simple inputs from the brain and create outputs as rhythmic patterns of movement as outputs. Descending modulation is what Auke calls the brain, processing information and sending movement signals to the body.
Pleurobot is part of an ongoing project to better understand the spinal cord in living beings, by creating spinal cord models and validating the design and systems on robots. The project starts simple on lampreys, moves up to salamanders, then cats, and finally humans. Progression is added at each level when building the spinal cord control system and the physical robot to test the controls.
Auke likes the salamander for a model because of the way the animal links the swimming motions of fish and the walking motions of mammals. He also points out that today's salamander is very close to the locomotion patterns of the first terrestrial vertebrate, and that makes the animal a kind of living fossil.
The anguilliform swimming gait is demonstrated first, as the muscle activity moves from the head to the tail. When the robot is placed on the ground it switches to a walking trot gait. The studies along with an X-ray machine from Jena University allow Ijspeert and his team to figure out which bones are important during each motion, and create videos of those motions in three dimensions.
Cheetah cub robots are also demonstrated in this talk, showing not just the robotic system but tying the robot's structure to kinematic pantographs. The cub robot's gait is created with an open loop, no sensors or feedback controls are required, just a constant signal to tell the robot how to move.
The robot demonstrations in this talk are incredible to me because of their ability to mimic animal systems and the idea that these robots are a tool to better understand biology. Ijspeert also mentions his upcoming projects where robots will do search and rescue operations with audio and video functionality attached to the system.