Reinforcement Learning with Dynamic Movement Primitives for Obstacle Avoidance

• Published in: Applied sciences 2021-12, Vol.11 (23), p.11184
• Main Authors: Li, Ang, Liu, Zhenze, Wang, Wenrui, Zhu, Mingchao, Li, Yanhui, Huo, Qi, Dai, Ming
• Format: Article
• Language: English
• Subjects: Algorithms; Behavior; Dynamic Movement Primitives; Learning; Neural networks; Obstacle avoidance; PI2 (policy improvement with path integrals); Reinforcement; reinforcement learning; Robot arms; Robots; Teaching methods
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app112311184

Dynamic movement primitives (DMPs) are a robust framework for movement generation from demonstrations. This framework can be extended by adding a perturbing term to achieve obstacle avoidance without sacrificing stability. The additional term is usually constructed based on potential functions. Although different potentials are adopted to improve the performance of obstacle avoidance, the profiles of potentials are rarely incorporated into reinforcement learning (RL) framework. In this contribution, we present a RL based method to learn not only the profiles of potentials but also the shape parameters of a motion. The algorithm employed is PI2 (Policy Improvement with Path Integrals), a model-free, sampling-based learning method. By using the PI2, the profiles of potentials and the parameters of the DMPs are learned simultaneously; therefore, we can optimize obstacle avoidance while completing specified tasks. We validate the presented method in simulations and with a redundant robot arm in experiments.