Legged Robot

A robot that moves on legs instead of wheels, such as a quadruped or bipedal humanoid.

A legged robot moves by alternately placing its legs on the ground, and is classified by leg count as bipedal (humanoid), quadruped (robot dog), hexapod, and so on. Compared with wheeled robots, it only needs discrete footholds, so it can climb stairs, cross obstacles, and cover gravel and grass, making it suited to unstructured environments; the tradeoff is that control is hard, since it must keep its balance in real time. Early methods relied on model-based control, such as MPC or the zero moment point; in recent years the mainstream approach trains a locomotion policy with reinforcement learning in simulation, then transfers it to the real robot. Representative examples include Boston Dynamics' Spot, Unitree's Go2, ANYmal, MIT's Mini Cheetah, and various humanoid robots.

ExampleA Unitree Go2 quadruped walks over stairs and grass using a gait trained with reinforcement learning.

Related

Quadruped Robot · Bipedal Robot · Legged Locomotion · RL-based Locomotion Control · Wheel-legged Robot · MIT Mini Cheetah

Sources

IEEE Spectrum: How MIT's Mini Cheetah Can Help Accelerate Robotics Research