Optimizing Execution of Dynamic Goal-Directed Robot Movements with Learning Control
This work addresses stability and efficiency issues in dynamic robot control for tasks like table tennis, offering an incremental improvement over existing learning control methods.
The paper tackled the problem of learning to track dynamic robot movements with inaccurate models, proposing a new adaptive Iterative Learning Control algorithm that achieved accurate tracking in simulations and on a robotic table tennis platform, outperforming high-gain PD-control and other ILC methods.
Highly dynamic tasks that require large accelerations and precise tracking usually rely on accurate models and/or high gain feedback. While kinematic optimization allows for efficient representation and online generation of hitting trajectories, learning to track such dynamic movements with inaccurate models remains an open problem. In particular, stability issues surrounding the learning performance, in the iteration domain, can prevent the successful implementation of model based learning approaches. To achieve accurate tracking for such tasks in a stable and efficient way, we propose a new adaptive Iterative Learning Control (ILC) algorithm that is implemented efficiently using a recursive approach. Moreover, covariance estimates of model matrices are used to exercise caution during learning. We evaluate the performance of the proposed approach in extensive simulations and in our robotic table tennis platform, where we show how the striking performance of two seven degree of freedom anthropomorphic robot arms can be optimized. Our implementation on the table tennis platform compares favorably with high-gain PD-control, model-free ILC (simple PD feedback type) and model-based ILC without cautious adaptation.