# Aerial Robot Control in Close Proximity to Ceiling: A Force Estimation-based Nonlinear MPC

## TL;DR

This paper presents a novel control framework for UAVs to perform safe, precise, and power-efficient close proximity flights near ceilings, using force estimation and nonlinear model predictive control.

## Contribution

A new control approach combining force estimation and nonlinear MPC enables UAVs to fly safely within 1 cm of ceilings, addressing complex nonlinear dynamics and safety constraints.

## Key findings

- UAV stabilizes at 1 cm from ceiling
- Power consumption reduces by up to 12.5% near ceiling
- Effective in complex nonlinear proximity environments

## Abstract

Being motivated by ceiling inspection applications via unmanned aerial vehicles (UAVs) which require close proximity flight to surfaces, a systematic control approach enabling safe and accurate close proximity flight is proposed in this work. There are two main challenges for close proximity flights: (i) the trust characteristics varies drastically for the different distance from the ceiling which results in a complex nonlinear dynamics; (ii) the system needs to consider physical and environmental constraints to safely fly in close proximity. To address these challenges, a novel framework consisting of a constrained optimization-based force estimation and an optimization-based nonlinear controller is proposed. Experimental results illustrate that the performance of the proposed control approach can stabilize UAV down to 1 cm distance to the ceiling. Furthermore, we report that the UAV consumes up to 12.5% less power when it is operated 1 cm distance to ceiling, which is promising potential for more battery-efficient inspection flights.