This paper presents the development and experimental validation of a bio-inspired autopilot, called TauPilot, based on the ecological tau theory proposed by the psychologist David Lee. Tau theory postulates that animals and humans use a combination of simple guidance strategies and the tau variable (τ) (representing time-to-contact) to prospectively guide and control most of their purposeful movements. This research investigates the feasibility and effectiveness of applying tau theory principles to guidance and control of movement in four dimensions (three spatial dimensions plus time), with application to various crucial maneuvres of unmanned aircraft systems (UAS) such as braking, automated aerial docking and automatic landing. TauPilot includes a tau-guidance system, a tau-navigation system and a tau-controller, resulting in a four-dimensional (4D) guidance, navigation and control system that has the capability to accurately fit maneuvres or actions into 4D slots using only the universal temporal variable, tau. TauPilot has been integrated into two rotorcraft UAS and demonstrated in more than 1000 successful tau-controlled flights. TauPilot provided the UAS with the capability to perform the following maneuvres with high spatial and temporal accuracy: tau-braking, 4D straight- and curved-path tau-docking to a virtual target (a three-dimensional point in space), vertical and 4D coordinated tau-landing, and 4D tau-interception of a moving target point.
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