Development of an autonomous omnicopter aerial vehicle

Abstract

Traditional multirotors and helicopters control translational movement by changing the orientation of the entire vehicle. This limits the effectiveness of such vehicles in applications as a mobile manipulator base. In these applications it is often necessary to fly in proximity to large structures where unpredictable aerodynamic conditions exist. In order to maintain precise control of position it is necessary to counteract disturbance forces quickly, and, due to the delay induced by rolling and pitching the entire vehicle, traditional multirotors and helicopters have a limited ability to maintain position precisely. Additionally, a mobile base must be capable of resisting arbitrary combinations of force and torque resulting from use of a manipulator arm. This is also not possible for traditional multirotors and helicopters. A novel Unmanned Aerial Vehicle (UAV) concept is presented which features the addition of four rotors directed orthogonally to the main lift rotors of a traditional quadrotor design. These rotors allow de-coupling of orientation from translational movement. Tests done on a physical prototype demonstrated improvements in disturbance rejection and an ability to roll or pitch up to 20 degrees independently of translational movement, including the ability to move backwards at an angle. This type of motion is impossible for a traditional multirotor vehicle. By adding a goal velocity term to the control algorithm, the ability to match the position and velocity of a moving target was demonstrated. This, combined with the ability to control orientation independently of the direction of flight, gives the OmniCopter the ability to land on or dock with a moving target.