Speed regulation increases the robustness of a simple treadmill walker more than position control

Experiments have shown that humans walking on a treadmill strongly prioritize speed regulation from one stride to the next. Why this is so and what implications, if any, this has for fall risk is an open question. Here, we study the relationship between task-level regulation and global stability in a powered compass walker on a treadmill, with additional speed and position controllers. While both provide viable regulation strategies for treadmill walking, we find that speed regulation enlarges the walker's stability region much more than position control.