Enhanced Capture Point Control Using Thruster Dynamics and QP-Based Optimization for Harpy

Abstract

Our work aims to make significant strides in understanding unexplored locomotion control paradigms based on the integration of posture manipulation and thrust vectoring. These techniques are commonly seen in nature, such as Chukar birds using their wings to run on a nearly vertical wall. In this work, we developed a capture-point-based controller integrated with a quadratic programming (QP) solver which is used to create a thruster-assisted dynamic bipedal walking controller for our state-of-the-art Harpy platform. Harpy is a bipedal robot capable of legged-aerial locomotion using its legs and thrusters attached to its main frame. While capture point control based on centroidal models for bipedal systems has been extensively studied, the use of these thrusters in determining the capture point for a bipedal robot has not been extensively explored. The addition of these external thrust forces can lead to interesting interpretations of locomotion, such as virtual buoyancy studied in aquatic-legged locomotion. In this work, we derive a thruster-assisted bipedal walking with the capture point controller and implement it in simulation to study its performance.

Figures (9)

• Figure 2: Illustrates the Harpy platform, which motivates our thruster-assisted dynamic legged locomotion.
• Figure 3: Shows the Harpy reduced-order model with thrusters, represented by a single body and massless legs.
• Figure 4: Snapshots of Harpy dynamically trotting on flat ground.
• Figure 5: Harpy controller architecture.
• Figure 6: Illustrates Harpy states.