A Geometric Formulation of Multirotor Aerial Vehicle Dynamics

A geometric dynamic modeling framework for generic multirotor aerial vehicles (MAV), based on a modern Lie group formulation of classical screw theory, is presented. Our framework allows for a broad range of rotor-wing con gurations: any number of rotors can be attached in arbitrary con gurations to either the body or wings, with the rotors and wings also tiltable. Our framework takes into account all masses and inertias of the MAV body and rotors, and accounts for both rotor thrust forces and moments as well as external aerodynamic and other forces. Compared to existing methods, our Lie group framework possesses several practical advantages useful for applications ranging from design optimization to model identi cation and trajectory optimization: (i) the dynamic equations can be easily transformed to coordinates of any reference frame; (ii) kinematic and mass-inertial parameters can be easily factored from the dynamic equations; (iii) exact, closedform analytic derivatives of the dynamics with respect to the con guration variables are easily derived. We demonstrate our systematic modeling procedure on examples of xed-tilt, variable-tilt, and hybrid MAVs with wings.

Polygonal plot scaling method for plant protection of rotor-like UAVs

In this paper, a universal polygonal block boundary method is proposed to solve the problem of integral shrinkage and integral expansion of the boundary of the operation area when facing complex operation area boundary and obstacle boundary in the plant protection process of rotor-wing unmanned aerial vehicles (UAVs). When rotorcraft UAVs carry out plant protection operation, they cannot spray more or miss spraying, and they cannot have any collision with obstacles. Based on the method proposed in this paper, the boundary of the operation area and the boundary of the obstacles can be shrunk and expanded as a whole, so as to improve the safety factor of UAVs and the operation accuracy and efficiency.

Performance simulation of multi-stage axial-flow compressor of turbo-shaft engine with account for erosive wear nonlinearity of its blades

The construction and useful practice of gas-turbine engine diagnosis systems depend largely on the availability of the engine mathematical models and its certain components in their structure. Utilization of multi-stage axial flow compressor performance with account for erosive wear of its parts during the operation fundamentally raises possibilities of such systems as erosive wear of flow channel, blade rings of impellers and vane rings of multi-stage compressor is a common cause of preschedule gas-turbine engine detaching from an aircraft. As evidenced by various contributions presented in the article, special emphasis on abrasive wear impact assessment on axial flow compressor performance is placed upon rotor-wing turbo-shaft engine due to their particular operating conditions. One of the main tasks in the process of mathematic simulation of an axial flow compressor blade ring is consideration of its wear type that again has a nonlinear distribution along the level of the blade. In addition, wear rate at entry and exit blade edges often have different principles. Detecting of these principles and their consideration when constructing the compressor mathematical model is a crucial task in diagnostic assessment and integrity monitoring of rotor-wing turbo-shaft engine in operation. The article represents a concept to an estimate nonlinear erosive wear effect of axial flow compressor blades on its performance based on the three-dimensional flow approach in the gas-air flow duct of compressor with a formulation of the blade rings. This approach renders possible to take into account the nonlinearity of the compressor blades wear during their operation. Through the example of the inlet compressor stage of a rotor-wing aircraft gas-turbine engine, the engine pump properties predictions with different kind of rotor blade wear have been presented.