Bipedal robots are garnering increasing global attention due to their potential applications and advancements in artificial intelligence, particularly in Deep Reinforcement Learning (DRL). While DRL has driven significant progress in bipedal locomotion, developing a comprehensive and unified framework capable of adeptly performing a wide range of tasks remains a challenge. This survey systematically categorizes, compares, and summarizes existing DRL frameworks for bipedal locomotion, organizing them into end-to-end and hierarchical control schemes. End-to-end frameworks are assessed based on their learning approaches, whereas hierarchical frameworks are dissected into layers that utilize either learning-based methods or traditional model-based approaches. This survey provides a detailed analysis of the composition, capabilities, strengths, and limitations of each framework type. Furthermore, we identify critical research gaps and propose future directions aimed at achieving a more integrated and efficient framework for bipedal locomotion, with potential broad applications in everyday life.
Performing highly agile dynamic motions, such as jumping or running, over uneven stepping stones has remained a challenging problem in legged robot locomotion. This paper presents a framework that combines trajectory optimization and model predictive control to perform consecutive jumping on stepping stones. In our approach, we firstly utilize trajectory optimization for full-nonlinear dynamics to formulate periodic jumps for various jumping distances. A jumping controller based on model predictive control is then designed for dynamic jumping transitions, enabling the robot to achieve continuous jumps on stepping stones. The proposed framework is also validated to be robust to platforms with unknown height perturbations and model uncertainty (e.g. unknown load). Moreover, experiments are also conducted to show the robustness of our jumping controller on an unknown uneven platform.