Research On Configuration Synthesis Of Lunar Rover Locomotion System And Development Of ALR Principle Prototype

Rover locomotion system is one of the important tools for lunar exploration and carrier, which plays an important role in the lunar exploration. Recently many new types of rover locomotion system are proposed, but most of them aren't consistent, such as function, structure and dimension. These locomotion systems have their respective advantages and disadvantages. The design principles are also different. There is no theory and criterion for the design of lunar rover locomotion system. It is lack of unified evaluation criterion such as which performances lunar rover should have, which technologies meet the requirements of lunar exploration. So there are important research significance and application value in the aspects of research on configuration synthesis of lunar rover locomotion system and developing high performance locomotion system.According to structure composition of locomotion system this paper do some research on the configuration of wheel, suspension subsystem and differential mechanism. The topology graphs of the suspension subsystem are built based on graph theory. New topology graphs are rebuilt by adding wheel to the suspension subsystem. ALR (Articulated Lunar Rover) locomotion system suspension configuration is proposed through the mechanism synthesis of suspension subsystem for 4, 6 and 8-wheel rover locomotion system. Configuration synthesis of gear differential is carried out based on graph theory. Three types of gear differentials are found. A separating rope differential is proposed in this paper. Also configuration characteristics of separating type differential are summarized. Some other differential configurations are obtained by configuration combination. The method for improving draw-bar pull is analyzed according to theory of mechanism and two kinds of wheel configurations are put forward.Multi-objective optimization mathematical model is established, which takes minimum torque surmounting obstacle and load platform pitch angle as optimization objection for ALR suspension. Then structure parameters of ALR are optimized by sequential quadratics programming and suspension parameters of ALR suspension are determined. According to the results ALR locomotion system is designed including wheel, rope differential and steering gear. At last ALR locomotion system principle prototype used in ground test is developed (shortened name is ALR principle prototype). Simulation terrain has been studied for performance analysis of ALR locomotion systems principle prototype, the ways of establishing the typical and random terrain are given. ALR principle prototype virtual simulation model is built, analysis of its trafficability, stability, surmounting obstacle capability and differential performance on soft terrain are carried out. Then the capability of ALR and FAYC(Fang An Yang Che) which adopts the locomotion system of rocker-bogie is analyzed and compared. Simulation results indicated ALR locomotion system have better performance on load platform pitch angle, driving efficiency, obstacle-crossing capability and slip ratioThe relationship between performance and configuration parameters is analyzed based on terramechanics. According to the analysis results and the rule of technique, the index system of the performance evaluation for the rover locomotion system is established. To evaluate the performance of ALR principle prototype, the evaluation system is established based on the method of entropy weight and analytical hierarchy process comprehensive evaluation. The evaluation result is creditable, for the index of weight coefficient is confirmed by the methods of subjective and objective analysis, which use the experience of experts for references and respect the objective relationships of index. A software is developed based on the evaluation model. The performance of ALR principle prototype is evaluated by the software. For comprehensive evaluation ALR performance, evaluation comparison between ALR and FAYC locomotion system is carried out and analysis result indicates ALR locomotion system principle prototype has better mobility performance.To implement indoor experiment, the control and measure system is established. The tractive force and turning torque of ALR principle prototype is measured with the six-axis force/torque sensor. To analysis the locomotion performance of FAYC and ALR principle prototype, the rover locomotion system FAYC is developed. Also, the experiment of FAYC is done. The results show that ALR possesses higher performance of obstacle-crossing, wheel load-distributing and slip ratio.