Turn control of a three-dimensional quasi-passive walking robot based on forced entrainment

A turn control strategy was proposed in order to enable a quasi-passive walking robot to turn on flat ground by utilizing a mechanical oscillator based on forced entrainment. The target trajectory of the mechanical oscillator was determined by online planning of its period, phase, amplitude and angle of the central axis of oscillation. The turn radius can be controlled by adjusting the inclination angle of the central axis of the mechanical oscillator movement. The control method was numerically and experimentally examined. The results show that the robot can turn with different turn radius and it is possible for the robot to walk in various environments.