Design And Experimental Research On Steering System Of A Coaxial Dual-rotor Mars Vehicle

In recent years,Mars exploration has been one of the most important goals of human space exploration.Many space probes have landed on Mars and used the Mars rover to survey the Martian environment and the surface.As the behavior of the Mars rover is affected by the complicated topography of Mars,scientists consider using a Mars vehicle instead of the Mars rover.A necessary condition for the feasibility of a Martian vehicle is that there is a thin atmosphere on Mars,and the rotor can generate lift to achieve the function of a ground vehicle.The coaxial dual-rotor Mars spacecraft has the advantages of compact structure and high lift-drag efficiency,which is the mainstream direction of Mars spacecraft research.The steering mechanism is a common control device for helicopter-like aircraft,which can control the Martian aircraft to hover and fly forward stably.The steering mechanism of the coaxial dual-rotor Mars aircraft follows the principle of helicopter control,and can control the pitch angle of the aircraft blades through the movement of the multi-degree-of-freedom mechanism,thereby manipulating the aircraft to tilt in the theoretical direction.Through the formulation of staged steering mechanism performance indicators,the mechanism principle and structure configuration of the steering mechanism are designed according to the performance indicators and design requirements,and the working space and output effect of the mechanism are increased by changing the rod parameters.Through theoretical solution,simulation analysis and experimental research,the kinematics characteristics of steering mechanism are comprehensively studied.The kinematics theory of the three-input three-output steering system is determined by solving the relationship between the lower ring of the swash plate,the upper ring of the swash plate and the attitude transformation of the swash plate.The kinematics model equations are numerically solved by calculation software,and the numerical solution results are fitted to study and analyze the fitting function of the kinematics theory of steering mechanism.By establishing a simplified kinematics model of the steering mechanism,the control variable method is used to study the relationship between the total pitch angle,the longitudinal periodic pitch angle,the transverse periodic pitch angle and the input amount of the rotation angle.The theoretical inverse kinematics equation of the steering mechanism is obtained by fitting experimental data,which is compared and analyzed with the theory.The electrical part of the steering system is composed of a drive unit and a control unit,which mainly includes a power supply circuit,a six-axis inertial measurement module,a three-axis inclinometer module,and a laser altimeter module.I choose chips that meet the test requirements to build the circuit and make the main control board and drive board and power supply board.The installation location and installation dimensions is determined according to the design model.The driver program is writed based on a self-made drive circuit to meet the dual closed-loop control requirements of the position closed-loop and speed closed-loop control of the steering motor.The upper and lower computer programs of the steering mechanism test and research are compiled,so that it can ensure the safety and sealing of the test,and finally achieve the goal of the hover attitude control test of the aircraft.In order to test and study the steering system of a coaxial dual-rotor Martian aircraft,it is necessary to design a test device that can carry the dynamic load of the aircraft and enable the aircraft to have pitch,roll,yaw and high degrees of freedom.The entire test bench is installed in a low-pressure container that simulates the Martian atmosphere,and mounted on a pulley block to offset the gravity difference between the Earth and Mars.In view of the various factors that affect the hover attitude control test,repeated tests are carried out to study its influence on the roll azimuth and roll angle of the aircraft,and substitute it into the control system to realize the hovering flight of the aircraft.