Learning while preventing mechanical failure due to random motions

Learning can be used to optimize robot motions to new situations. Learning motions can cause high frequency random motions in the exploration phase and can cause failure before the motion is learned. The mean time between failures (MTBF) of a robot can be predicted while it is performing these motions. The predicted MTBF in the exploration phase can be increased by filtering actions or possible actions of the algorithm. We investigated five algorithms that apply this filtering in various ways and compared them to SARSA(λ) learning. In general, increasing the MTBF decreases the learning performance. Three of the investigated algorithms are unable to increase the MTBF while keeping their learning performance approximately equal to SARSA(λ). Two algorithms are able to do this: the PADA algorithm and the low-pass filter algorithm. In case of LEO, a bipedal walking robot that tries to optimize a walking motion, the MTBF can be increased by a factor of 108 compared to SARSA(λ). This indicates that, in some cases, failures due to high frequency random motions can be prevented without decreasing the performance.