Simulation of a Coaxial Unmanned Martian Helicopter Motion in Virtual Environment Systems

The paper considers the task of coaxial unmanned Martian helicopter motion simulation in virtual environment systems. To solve this task, a nonlinear mathematical model of helicopter dynamics with blade flapping motion is presented. This model also includes nonlinear equations for computing rotor thrust coefficients. The proposed solution for helicopter control is to use the feedback linearization method of nonlinear equations. Based on this approach, a control of the vertical and horizontal helicopter motion was implemented. Regarding this, expressions for the roll and pitch angles of helicopter relative to required rotor thrusts and aircraft accelerations were derived. The control results in the relationship for collective and cyclic pitch angles for both rotors. To ensure these angles, PD regulators were used, implementing computation of voltages supplied to the helicopter's swashplate actuators. The approbation of methods and algorithms proposed in the paper was carried out in our virtual environment complex, exemplified on the control of virtual coaxial helicopter using a training remote controller. Aiming this, software modules for helicopter dynamics simulation and control were developed and added to the complex. For this, a semi-implicit Euler scheme to integrate differential equations, and Newton's numerical method to solve nonlinear equations, were used. The helicopter control is implemented by means of a functional diagram scheme which inputs are commands from the remote controller and measurements from virtual sensors, and the voltages for actuators are generated at the output. Approbation results showed the adequacy of the solutions proposed in the paper, which can be further used in creation of simulators designed for teaching operators to control a coaxial Martian helicopter.