Development of hardware-in-the-loop facility for optical navigation with the study of insect inspired algorithm for spacecraft landing

Abstract

The thesis objective was to develop a real-time interface to the robot controller and related software components in the hardware-in-the-loop simulation facility for optical navigation. For demonstration of the developed components, an insect-inspired landing algorithm using a camera was chosen to study along with the hardware-in-the-loop simulation development. The testing of the algorithm in the hardware-in-the-loop simulation provided the evaluation of the algorithm itself as well as the functional test of the hardware-in-the-loop software components. In this thesis, two simulation platforms were presented. First, the simulation platform using planetary image generation software was setup. The landing algorithm acquired image data from the image generation software by providing spacecraft dynamics information to the software. After image processing, the algorithm provided the feedback control to control the spacecraft. Second, the hardware-in-the-loop simulation software components were setup in the facility in German Aerospace Centre (DLR). The robotic arm carrying a camera was controlled to approach the scaled terrain model. Simple spacecraft dynamics was performed and transformed to the robotic arm movement. Reference frames for the transformation were defined. The real-time control software for the robotic arm was developed and the closed-loop control in the hardware-in-the-loop simulation was setup. Finally, control signals from the image processing module were transferred to change spacecraft dynamics in the simulation resulted in changing the movement of the robotic arm. An insect-inspired algorithm using optical flow from a camera for controlling the spacecraft during the landing was presented. The image processing for the optical flow determination and interpretation were described. The characteristics of the optical flow were studied. The control law for controlling the spacecraft velocity according to the optical flow was designed according to the optical flow characteristics. The delay in the control system was considered in the design of the control rule. The implementation of the algorithm with the tests in software-in-the-loop simulation and in the hardware-in-the-loop facility was presented. The landing algorithm can slow down the spacecraft and land softly both with image generation software and in hardware-in-the-loop simulation. The system with the delay was studied. The developed control rule can control the delayed system effectively. The thesis has shown that the insect- inspired landing algorithm using only the optical flow calculation is feasible for the landing of the spacecraft.Validerat; 20101217 (root