Figure 13.

Fast online learning of a static feedback controller for a Matsuoka oscillator on ReCTeR based on uncalibrated strain-gauge sensors. The top left plot shows the fraction of feed-forward versus feedback control. During learning, both feedback and feed-forward controllers (training signals) are active. The influence of the open-loop feed-forward controller decreases, and when its fraction is below 0.2, learning stops and only the trained feedback controller is active. The left plot on the second row shows vertical coordinates (in millimetres) of the four end caps with the largest vertical displacements as a function of time. The five surrounding plots are details of this plot, showing different training and testing phases. (a) Fully open-loop control. (b) Switch from partially open-loop and feedback control to full feedback control, learning stops. (c) We perturb the robot by pushing it down, preventing all movements. (d) The feedback controller recovers after the robot was lifted from the ground. (e) Behaviour of the robot after 250 s (170 s closed loop).