Study On Ultrasonic Measurement Technology Of Model’s Position And Pose For Low Speed Wind Tunnel Test

Multi-function Icing Wind Tunnel was established in December 2013 as a Major Science and Technology Infrastructure for our country. The model’s position and pose measurement system is the main part of the wind tunnel measurement and control system, and its performance is essential to the comprehensive performance of the wind tunnel. It is very inportant to take a real-time, non-contact, high accuracy and reliable model’s position and pose measurement technique and method for low speed wind tunnel test for the particularity of the wind tunnel test environment and accuracy requirements of low speed wind tunnel model’s position and pose. Based on all model’s position and pose measurement methods used in low speed wind tunnel at home and abroad, a non-contact measuring method and theory of low speed wind tunnel model’s position and posture based on ultrasonic measurement technology is proposed in this article for the first time, and the theory and calculation methods are studied in detail. The main work and results show that:(1) Establish a perfect theory model on non-contact ultrasonic measurement of the low speed wind tunnel model’s position and pose, including five relative independent parts: ultrasonic accurate distance measuring theory, single point ultrasound space location mathematical model and algorithm, identification model’s position and pose mathematical model and algorithm, and the position and pose ultrasonic measurement system calibration. The ultrasonic accurate distance measuring theory is used to measure accurate distance between the emitted and received sensor which are matched. The single point ultrasound space location mathematical model and algorithm is used to obtain coordinates in the wind tunnel of the target ultrasonic sensor installed on the model. The identification model’s position and pose parameter mathematical model and algorithm is used to solve the position and pose of the model during the wind tunnel test. The position and pose ultrasonic measurement system calibration includes the calibration of beacon ultrasonic sensor and target ultrasonic sensor coordinates, and distance between matched real-time sound velocity sensors.(2) The ultrasonic accurate distance measuring theory is used to measure the accurate distance between beacon ultrasonic sensor fixed on the inner wall of the closed test section(or the model boundary of the open test section) and target ultrasonic sensor fixed on the model. The single point ultrasonic space location mathematical model solves coordinates value the target sensor in the wind tunnel coordination by accurately measuring distances between a same target ultrasonic sensor with at least three beacon ultrasonic sensors and combination method. Analyzing this calculation method, this paper gives an optimal measurement structure to solve the target ultrasonic sensor coordinate, and verifies the efficiency and reliability of the single point ultrasound space location mathematical model and algorithm.(3) The identification model’s position and pose mathematical model and algorithm is a rigorous mathematical model and includes an axis systems transformation model and a pose solving model. The axis systems transformation model solves translation parameters and rotation parameters of the model coordination to the wind tunnel coordination by using at least three points coordinate in the model coordination and the wind tunnel coordination respectively, gravity treatment and variable separation methods. On the base of these works, the pose solving model can obtain model’s position and pose during wind tunnel test by analyzing translation and rotation matrix between coordinates system. Analyzing method of solving coordinates system transformation matrix in the identification model’s position and pose parameter mathematical model, this article proposes a point reconstruction theory of common points of two coordinates system in the wind tunnel coordinates system and two calculation models: equality solving model and multi-goal programming model. For solving of point reconstruction, we suggest multi-goal programming model.(4) The position and pose ultrasonic measurement system calibration theory is used to verify the measurement of this applied system. For the coordinate values and the measurement error of fixed location of the beacon ultrasonic sensor and the real-time sound velocity measurement ultrasonic sensor, this article proposes a basic point calibration method to calibration; for the distance measurement of real time sound velocity sensors, this article proposes basic point calibration method and a difference method. Considering the measurement accuracy requirements, the difference method is suggested to calibration; for the coordinate values and measurement error in the model coordinate system of the target ultrasonic sensor fixed on the model, this article proposes a coordinate superposition method to calibrate.(5) Take a 3m×2m Multifunction of Icing Wind Tunnel as an example, this article proposes a model’s position and pose ultrasonic measurement system design scheme used for No.1 4041 standard model test in the Icing Wind Tunnel and gives out system components, layout design of target ultrasonic sensor, beacon ultrasonic sensor and real time sound velocity measurement sensor, system calibration and calibration design, and measurement program, measurement steps and so on.