Barrier Functions in Cascaded Controller: Safe Quadrotor Control
This work addresses the challenge of safe control for inherently unstable quadrotors with multiple dynamic constraints, but the method is incremental as it applies existing CBF techniques to a cascaded architecture.
The paper proposes a QP-based approach using control barrier functions on a cascaded control architecture to enforce multiple dynamic constraints for safe quadrotor control, demonstrating feasibility in simulation with simultaneous position and velocity constraints.
Safe control for inherently unstable systems such as quadrotors is crucial. Imposing multiple dynamic constraints simultaneously on the states for safety regulation can be a challenging problem. In this paper, we propose a quadratic programming (QP) based approach on a cascaded control architecture for quadrotors to enforce safety. Safety regions are constructed using control barrier functions (CBF) while explicitly considering the nonlinear underactuated dynamics of the quadrotor. The safety regions constructed using CBFs establish a non-conservative forward invariant safe region for quadrotor navigation. Barriers imposed across the cascaded architecture allows independent safety regulation in quadrotor's altitude and lateral domains. Despite barriers appearing in a cascaded fashion, we show preservation of safety for quadrotor motion in SE(3). We demonstrate the feasibility of our method on a quadrotor in simulation with static and dynamic constraints enforced on position and velocity spaces simultaneously.