Humanoid Robot Motion Planning Approaches: a Survey

Humanoid robots are complex, dynamic systems. Any humanoid robotic application starts with determining a sequence of optimal paths to perform a given task in a known or unknown environment. This paper critically reviews and rates available literature on the three key areas of multi-level motion and task planning for humanoid robots. First is efficiency while navigating and manipulating objects in environments designed for humans. Here, the research has broadly been summarized as behavior cloning approaches. Second is robustness to perturbations and collisions caused by operation in dynamic and unpredictable environments. Here, the modeling approaches integrated into motion planning algorithms have been the focus of many researchers studying humanoid motion's balance and dynamic stability aspects. Last is real-time performance, wherein the robot must adjust its motion based on the most recent sensory data to achieve the required degree of interaction and responsiveness. Here, the focus has been on the kinematic constraints imposed by the robot's mechanical structure and joint movements. The iterative nature of solving constrained optimization problems, the computational complexity of forward and inverse kinematics, and the requirement to adjust to a rapidly changing environment all pose challenges to real-time performance. The study has identified current trends and, more importantly, research gaps while pointing to areas needing further investigation.