| New folding wing aircraft which can fold or expansion the wing in flight to maintain the best aerodynamic performance, in response to requirements of a variety mission,is an important development of smart morphing aircraft, which capture domestic and international aviation industry and scholars'attention in recent years. Actuation system is the heart of a machine, and the design of a large number of distributed actuators is a key technology of folding wing aircraft design.Traditional single actuator can't be applied to folding wing aircraft because of their disadvantage. SMA actuator has high power weight ratio and larger output force, but it is not easy to achieve precise position control and can't be self-locking. DC motor has a higher positioning accuracy, but the power weight ratio is lower. It can't be used in equipment which has higher requirements of the quality and size. This requires a new actuator that has small size, light weight, large output force, and high precision position control.We review the recent development of folding wing aircraft and the hybrid actuator first, then discuss several folding-wing aircraft and the principle of hybrid actuator for the special needs of aerospace, and then propose a concept that "SMA- linear motor hybrid actuator". The hybrid actuator has both the SMA's larger output force and the motor's higher precision displacement control. SMA-motor hybrid actuator can be used as the driving source of folding wings, and then we design a transmission mechanism of folding wing based on this actuator.First, we design transmission and drive mechanism of the folding wing. Establish the mathematical model of the crank slide mechanism. We make the constrained multi-objective optimization design about force and displacement of the crank slide actuator mechanism though Numerical Analysis Software and Multi-body dynamics software, to obtain the size parameters based on the requirements of the subject. Determine the support reaction force of the deputy campaign under the given load by dynamic simulation, in order to provide geometry and physical parameters for the design of hybrid actuator.Then, design the SMA-motor hybrid structure. Analyze the principle of hybrid actuator and design the parallel mode SMA-motor hybrid actuator prototype. The major part of the screw and the bearing force was checked. The appropriate motor is selected through theoretical calculations and simulation. Establish the dynamic equation of the screw nut, the SMA phase transformation kinetics equation and the DC motor model, to maintain the dynamical systems state space equation of the hybrid actuator. Create system simulation model to get the dynamics and kinematics curve of the hybrid actuator. Design whole of the three-dimensional model, then manufacture the hybrid actuator prototype.Last, coordinated control strategy of SMA and motor is proposed, which make the use of the gapΔP of screw nut. Variable duty cycle voltage is applied to the motor in order to drive the screw follow-up SMA's movement rapidly. The specific steps of control scheme is given, then design and produce a hybrid actuator control system, complete the integration assembly of mechanical parts and circuit. Do the simulation and make experimental tests of the control system.Simulation and experimental results show that the hybrid actuator not only provide larger output force but also achieve higher precision position control and its position can be locked. This new actuator can be used for new folding wing aircraft. |
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