Modificaiton Of Wheel-Soil Contact Dynamic Model And Simulation Of Six-Wheel Driving-Steering Mars Rover

Successful lunar exploration has helped humans know more about planets other than the earth and ushered in a worldwide upsurge of Mars exploration by wheeled robots(rovers).So far,China,the U.S.,Russia and European Space Agency(ESA)have announced their 2020 Mars exploration programs,initiating a challenge for rovers to make normal operation on soft but rugged terrain.In this respect,studies on wheel-soil interaction dynamics models are pretty conducive to rover design,navigation control system design,performance evaluation and dynamic simulation of rovers among others.Current studies are mostly concerned with the conventional terrain vehicle mechanics.However,rovers have a great difference from terrain vehicles regarding the running environment,structural dimensions,control mode,etc.and it is hard to do a mobile performance experiment on rovers in a completely simulated non-earth planetary environment on the earth.Therefore,it is imperative to study wheel-soil interaction dynamics models of rovers and make dynamic simulation of rovers.And to study terrain mechanics models of rovers,correction of traditional terrain vehicle mechanics models counts.Through a contrastive analysis on the Bekker model,Wong-Reece model,and Janosi model,it is concluded that the Bekker model is to be corrected.And through a comparison between calculated results and experimental results of the Bekker model,the orientation of model correction is determined,where slip subsidence impact is taken into account.Based on the preceding findings,the model is extended in three dimensions;meanwhile,to make the model applicable to simulation,the model is further corrected.To build an accurate Mars rovers dynamics model,theories of multi-body dynamics are combined with ADAMS in modeling.Since ADAMS cannot be directly used to build dynamics models for special mechanisms,motor-driven torque or wheel-soil interaction,a modeling method is put forward for special mechanisms,motor-driven torque and wheel-soil interaction.In this method,a Mars rover dynamics model is set up and verified.And a Mars rover motion simulation platform is needed for the dynamic simulation of the model.Based on the Mars rover dynamics model,the Mars motion simulation platform is designed and put into practice.Built on the ground of the ADAMS software.this simulation platform comprises a dynamic generation module,dynamic computation module,master control program module,navigation instruction module and post-processing module.It is verified that this simulation platform can implement real-time simulation,which has been used in China's Mars exploration mission at the moment.By reference to fundamentals of terrain vehicle mechanics,a series of Mars rover performance evaluation indicators are offered.A simulated analysis is made on the Mars rover model under such typical working conditions as flat terrain,slope terrain,swerving,crawling,and lifting in the simulation platform in conjunction with the preceding performance evaluation indicators to ultimately implement a longtime massive simulation in natural terrains.