Multi-task learning by robots poses the challenge of the domain knowledge: complexity of tasks, complexity of the actions required, relationship between tasks for transfer learning. We demonstrate that this domain knowledge can be learned to address the challenges in life-long learning. Specifically, the hierarchy between tasks of various complexities is key to infer a curriculum from simple to composite tasks. We propose a framework for robots to learn sequences of actions of unbounded complexity in order to achieve multiple control tasks of various complexity. Our hierarchical reinforcement learning framework, named SGIM-SAHT, offers a new direction of research, and tries to unify partial implementations on robot arms and mobile robots. We outline our contributions to enable robots to map multiple control tasks to sequences of actions: representations of task dependencies, an intrinsically motivated exploration to learn task hierarchies, and active imitation learning. While learning the hierarchy of tasks, it infers its curriculum by deciding which tasks to explore first, how to transfer knowledge, and when, how and whom to imitate.

提出了一种多任务学习的层级强化学习框架，名为SGIM-SAHT，用于使机器人完成各种复杂的控制任务，并演示了该框架能够学习到基本的任务和复合任务之间的层次关系，从而实现了从简到难的任务学习，并通过表示任务依赖性、内在动机探索、主动模仿等途径，使机器人能够推断出自己的任务学习进度，并决定何时、如何、以及向谁进行模仿学习。

机器人内在动机和自动课程学习实现逐步复杂任务