Efficient locomotion control of biped robots on unknown sloped surfaces with central pattern generators

A closed-loop system for the central pattern generator (CPG)-based locomotion control of biped robots that operates in the joint space is presented. The proposed system has been designed to allow biped robots to walk on unknown sloped surfaces. Feedback signals generated by the robot´s inertial and force sensors are directly fed into the CPG to automatically adjust the locomotion pattern over flat and sloped terrain in real time. The proposed control system negotiates sloped surfaces similarly to state-of-the-art CPG-based control systems; however, whereas the latter must continuously solve the computationally intensive inverse kinematics of the robot, the proposed approach directly operates in the joint space, which makes it especially suitable for direct hardware implementation with electronic circuits. The performance of the proposed control system has been assessed through both simulation and real experiments on a NAO humanoid robot.