Research On Motion Control Of Multijointed Lunar Rover Based On RTAI

Because the multi-task lunar rover motion control system has the requirements of high real-time performance and system reliability, this dissertation carries out the research on the real-time motion control platform of the lunar rover and the related technology based on the RTAI (Real-Time Application Interface), aiming at the characteristics of multi-jointed rover mechanism and multi-wheel coordinated control. And the rover wheel servo characteristics and coordinated control implementation with RTAI are researched to give the foundation for the application of open platform of control system in the aerospace industry with RTAI.Taking the multi-jointed lunar rover with six cylinder-conical wheels as the research object, multi-mode motion control strategy is put forward, based on the classification of the unstructured lunar surface attributes and the rover mechanical characteristics. The motion modes can be divided into: passive terrain adaptation motion mode, wheel-walking motion mode, active passing obstacle motion mode and crossing ditch motion mode. The application and planning of these motion modes are analyzed and kinematics models of the rover motion on complicated uneven landform are set up, which lay the solid foundation for the multi-wheel coordinated control.To achieve the real-time requirement of the rover motion control system, this dissertation researches the method of improving real-time performance of the general OS, put forward the design and implementation of the interrupt processor and task scheduler of the real-time multi-task platform based on open sourced Linux, and set up the inter-task communication with method of device driver and soft interrupt mechanism, which give the theory guideline and useful reference for the realization of real-time multi-task platform based on the real-time OS.To realize the soft motion control which can reduce the hardware design complexity and improve system reliability, this dissertation put forward soft motion control platform based on RTAI, which has hard real-time performance. Based on the characteristics of rover motion control structure and RTAI, the implementation technology of open motion control system platform is researched, its multi-task model is realized with the RTAI real-time thread based on the threads cooperation model. The communication structure of lunar rover motion control is simplified with the command relay-transmit mode, by the analysis of RTAI communication.As an application example, open real-time control platform based on RTAI is realized in the motion control of multi-joint six cylinder-conical-wheel lunar rover. Effective motor control is import for the motion control system, so for the sake of research of performance evaluation and easy implementation of real-time motion control, a design method of real-time application based on RTAI-Lab is put forward, which can be used to save time spending and improve development reliability. To research the performance of the software hard real-time motion control system, the influence of delay and jitter on motor control is researched. Taking the lunar rover with six cylinder-conical wheels as example, this dissertation researches the coordinated control of multiple independent driven wheels to achieve the optimization of driving efficiency and locomotion accuracy.The real-time motion control system of six cylinder-conical-wheel lunar rover prototype based on RTAI is setup, and motion experiments are carried out. These experiments demonstrate the validation of the designed multi-wheeled coordinated motion control system and prove its feasibility.