Design And Analysis Of A New Type Of Electric Steering Gear For A Trajectory Correction Projectile

With the rapid development of modern warfare,higher requirements are needed on the guided munitions.The EMA(electro-mechanical actuator),as a key component of the two-dimensional trajectory correction projectile,whose system performance directly affects the ammunition's striking accuracy.Based on the 120mm two-dimensional trajectory correction projectile,a new type of EMA system was studied.The spatial mechanism RCCR with unequal setover and the harmonic gear drive were applied in this system.Through the theoretical calculation and simulation analysis,the system feasibility of the EMA was verified.Firstly,the kinematic theory calculation and simulation of the spatial mechanism RCCR's kinematics characteristics were carried out in this paper.Then,the working mechanism of the actuator was designed.Secondly,the kinetostatic of the spatial mechanism RCCR was analyzed and joint force(or torque)were solved.And the rigid-flexible coupling model of the RCCR mechanism was established by the ADAMS software.The results of the theoretical and simulation were compared and they fit well.The correctness of the simulation model were verified.Thirdly,the dynamic model of the EMA system,including the friction moment,moment of inertia and hinge moment,was established.The curve equation of the system's load characteristics was derived,based on the equation,the optimal reduction ratio of the reducer was calculated.Through the load matching,appropriate parameters of the motor performance were selected.Fouthly,according to the optimal reducer reduction ratio and the high load condition of the EMA,the main parameters and structure of the harmonic gear were designed.And the stress and strain distribution of harmonic gears,under no-load and under load,were analyzed by using the finite element software ANSYS.The results show that the harmonic gear reducer can meet the strength requirements of the EMA system.Lastly,the overall structure of the EMA system was designed,and the total transmission ratio was calculated.The motor output power and system transmission efficiency,with the friction torque and hinge moment,were studied.Theoretical analysis and simulation results show that,the new EMA system has the advantages of simple structure,good dynamic characteristics and high transmission efficiency,which is suitable for two-dimensional trajectory correction projectile.