This paper presents practical vision-based collision avoidance for objects approximating a single point feature. Using a spherical camera model, a visual predictive control scheme guides the aircraft around the object along a conical spiral trajectory. Visibility, state and control constraints are considered explicitly in the controller design by combining image and vehicle dynamics in the process model, and solving the nonlinear optimization problem over the resulting state space. Importantly, range is not required. Instead, the principles of conical spiral motion are used to design an objective function that simultaneously guides the aircraft along the avoidance trajectory, whilst providing an indication of the appropriate point to stop the spiral behaviour. Our approach is aimed at providing a potential solution to the See and Avoid problem for unmanned aircraft and is demonstrated through a series of experimental results using a small quadrotor platform.

This paper presents a new image-based visual servoing approach that simultaneously solves the feature correspondence and control problem. Using a finite-time optimal control framework, feature correspondence is implicitly solved for each new image during the control selection, alleviating the need for additional image processing and feature tracking. The proposed approach demonstrates mild robustness properties and leads to acceptable or improved image feature behavior and robot trajectories compared to classical image-based visual servoing, particularly for underactuated robots. As such, preliminary experimental results using a small unmanned quadrotor are also presented.