Motion Planning And Control During Fast Insertion Of Fast Insertion Mechanism

At present,research on hypersonic vehicles is on the rise.All the major space powers in the world have invested huge manpower and resources to seize the commanding heights of this future.The frictional heat generated by hypersonic flight poses a challenge to the safety and performance of hypersonic vehicles.The aerodynamic heat and thermal protection of hypersonic vehicles has become critical.Through the simulation experiments in the wind tunnel,the aerodynamic characteristics of the aircraft can be effectively simulated and predicted,which can guide the design and optimization of the aircraft thermal protection.During the heat flow measurement test of the wind tunnel,the time taken by the aircraft model to feed into the center of the flow field has the greatest impact on the accuracy of the test results.The development of the quick insertion mechanism can minimize the time for the aircraft model to enter the center of the flow field,and greatly improve the accuracy and reliability of the wind tunnel test data.However,the quick insertion mechanism needs to send the model into the center of the flow field in a very short time and complete the start-stop action,which requires extremely high speed and control precision.At the same time,the weight of the model and the tail strut causes a large load on the driving of the quick-insertion mechanism,and the motion inertia of the mechanism is large.The high speed,heavy load and start and stop in short range during the fast insertion process pose a challenge to the successful development of the quick insertion mechanism.Most of the existing quick insertion mechanisms are implemented by hydraulic or pneumatic driving,and have problems such as poor flexibility and low control precision.This paper investigates the use of a linear motor as a fast insertion motion implementation of the drive.The arrangement of the linear motor and the corresponding control implementation and accuracy assurance method are described.In particular,it provides a corresponding solution for the key technical difficulties such as high-speed heavy-duty,short-moment start-stop and short-time and high-precision control.The main work of this paper is as follows:In order to avoid the flexible impact during the fast insertion motion,the control of the acceleration and deceleration changes during the fast insertion motion is planned.By referring to the commonly used acceleration and deceleration control laws in the CNC center,the advantages and disadvantages of each acceleration and deceleration law are compared.The 3-4-5th polynomial acceleration/deceleration control algorithm and the improved five-segment trigonometric function algorithm are selected to accelerate and decelerate the fast-release process.The separately planned results are enumerated and the appropriate curves are selected for comparison.Finally,the improved five-segment trigonometric function acceleration and deceleration algorithm is selected as the acceleration and deceleration control law during the fast-moving motion.The timeliness and stability of the system movement are guaranteed.The synchronization problem of two linear motors is realized by the master-slave control method of direct torque distribution.The displacement curve is non-uniformly sampled using the velocity values at the same time as weights.A five-time polynomial curve is fitted between two adjacent sampling points for transition using five Hermite interpolations.A complex displacement curve is achieved by the electronic cam tool of the control system.Solved the problem that the control system cannot directly realize the planned complex acceleration and deceleration control curve.The mathematical model and system transfer function of the linear motor are established.According to the characteristics of the control system PID controller,the PI control of the system speed loop was simulated by MATLAB.Aiming at the problem of pneumatic load impact in the process of rapid insertion,based on the traditional PID control,the intelligent fuzzy PID adaptive control is adopted to improve the control precision and reduce the response time of the system speed loop.