Quadrupedal or four-legged robots, which can mimic animal walking gait, have long been studied as the most important branch of bionic robot application. They can perform tasks in the environment with rough terrain with great stability compared to bipedal robots. We have seen four-legged robots performing a lot of impressive things so far – from 360-degree backflip to playing soccer.
Now, roboticists at Tokyo Metropolitan University have built a quadruped that can climb vertical ladders without falling. Unveiled at IROS 2019 last week, the four-legged robot has five degrees-of-freedom legs that include a sort of opposable thumb that turns its feet into grippers, which help it to autonomously climb vertical handrail-free ladders.
Climbing a vertical ladder is quite difficult for four-legged animals. This is because, as the steepness of the ladder increases to vertical, your center of mass moves farther and farther away from the rungs. You have to support an increasing amount of your own weight by actively gripping rungs rather than just standing on them, which is a problem for animals that don’t have robust grasping systems.
The team used a recurrent neural network that trained this 7 kg robot to ascend the ladder. And now, they are planning to generalize the system so that the robot can climb any ladders without prior training.
The quadruped robot is equipped with an inertial measurement unit (IMU), a time-of-flight 3D camera on its face, and touch and force sensors on each claw. All these components help it to climb precisely. An Intel NUC computer acts as the main control system, with an Arduino used as a secondary controller to manage the input-output signals of the internal sensors, as IEEE Spectrum reported.
Besides, for smooth climbing, the robot comes with 23 degrees of freedom (DoF): 5 DoF in each leg, 2 DoF for the dual laser rangefinder sensors, and 1 DoF for the head.