Verification of the nozzle position in thrust vector control systems with image processing methods

The thrust vector control (TCV) system is a control system that changes the thrust direction of vehicles. Conventional methods of missile guidance cannot be used in non-atmospheric applications because they use aerodynamic surfaces, thus TCV systems are needed. TCV systems generally provide nozzle movement with two linear actuators. With the actuator sensors, it is found how many degrees the nozzle moves. However, a reference point is needed to measure this movement. Finding this reference point requires expensive mechanical parts and sensors. In addition, after the initial position is determined, the nozzle position sensors must be verified. In the thesis study, a system has been proposed considering these needs. In this system, the absolute angle of the nozzle is measured by estimating the depth with a Zed camera with stereo vision. For depth estimation, image rectifying and simple triangulation methods were used as well as camera calibration. Aruco markers are preferred for precise depth measurement. The resolution, which decreases with increasing distance in TCV system measurement, is increased by super resolution methods. The distortions in increasing resolution were corrected with the adaptive threshold value, and a precise depth calculation was made. According to the test results, it was observed that the depth errors in the measurements taken from distances up to 700 mm were below 1 mm and the standard deviation values were below 0.1 mm. The planes in the TCV system were obtained by using the least squares method by making precise depth measurements. The angle between the planes was calculated with the help of trigonometric formulas. The nozzle angle found was divided into the actuator axes (yaw and pitch) and when these angles were compared with the data from the actuator sensors, the maximum error was found to be 0.1642°. It is envisaged that this application, which was realized as a result of the thesis study and has a very low cost compared to its counterparts, is used in verification tests and the operation time and labor force can be reduced if the absolute nozzle position is determined according to the reference point found.