Underactuated drone arm writes precisely on vertical and inclined surfaces
Contact-Aware Incremental Model Predictive Control for an Underactuated Aerial Manipulator
Robotics
Summary
Controlling drones to touch surfaces accurately is hard because they have limited motors and face wind and friction. The authors designed a control method combining prediction and feedback techniques so a drone with a simple arm can write on walls precisely and steadily, even with disturbances. This method does not need complicated arms or special force sensors. They tested it both in simulations and real life on a drone that holds a pen to write on different surfaces with varying forces and wind.
What this means in practice
- •For drone developers: Enable drones with simple arms to perform precise contact tasks on walls without extra sensors or complex mechanics.
- •For industrial automation teams: Implement stable contact manipulation with aerial robots for inspection or surface operations in environments with wind or friction.
Authors
Darwin Liu, Tamas Keviczky, Sihao Sun
Abstract
We present a robust contact-aware control framework for aerial writing on an underactuated platform. The framework combines nonlinear model predictive control (NMPC) for accurate end-effector position and normal-force tracking at small reference penetration depths, with consistent performance across controller tunings, with whole-body incremental nonlinear dynamic inversion (INDI) for robustness to frictional and aerodynamic disturbances during contact. The proposed controllers are validated on a quadrotor-based aerial manipulator with a rigid, single-link, one-degree-of-freedom (DoF) arm in simulation and real-world experiments. The aerial writing experiments span vertical and inclined surfaces, multiple reference forces, different friction conditions, and wind disturbances. The results demonstrate that robust simultaneous five-DoF end-effector pose and contact-force tracking is achievable on a standard underactuated quadrotor with a simple, rigid, single-link arm, without requiring a fully actuated platform, a complex arm, or dedicated force/torque sensing.