| This paper aimed at the excellent character traveling on sand, basing on the structureand morphology of the ostrich foot, according to sandy environment characteristics and theprinciple of bionics engineering, the desert environment walking mechanism was studied,this article was aimed at improving the sandy trafficability. Through the analysis in thecontribution of ostrich toe traveling on sand, the touching sand device which was bionic andadaptive was designed in accordance with the contribution mechanism of ostrich foottraveling on sand, and the wheel surface structures were combined to study the trafficabilityof sandy rigid wheel traveling on sand, a new type of bionic walking wheel which has thehigh trafficability was developed.The research techniques of macroscopic observation, anatomical measurement, microsurface test and high-speed video analysis were adopted, the high-speed and stablemechanism of ostrich foot traveling on sand was overall studied, revealing the delicaterelationship among two-toed configuration, toe posture, four bones each toe, columnarmastoid group on foot bottom and scales at toe back and the ability of ostrich foot travelingon sand; The high-speed motion type of ostrich foot traveling on sand was studied, and theunique action mode of ostrich foot inserting sand, acceleration and high-speed break wereachieved.According to the way and posture of ostrich foot touching sand, the bionic self-adaptivemechanism was designed by using the engineering bionics technology. The bionicself-adaptive mechanism to support some load on sand was designed in the way ofsimulating the ostrich foot into sand. It can change the postures of touching sand, the initialtouch state, intermediate state and the ultimate bearing state, according to the bearing load,and it can surround the sand and restrict sand flow to prevent subsidence, avoid slip andincrease traction force. The process of bionic device inserting sand was simulated withdiscrete element method, the result was compared with that of the ordinary device, the bionicdevice had good performances of traveling on sand and load bearing were confirmed.Direct at the analysis in the influence of rigid sandy wheels with different surfacestrafficability, six wheel models with different radian surfaces of concave, convex and planewere made to conduct the static subsidence experiment and dynamic platform experimentunder the condition of three different particle size sand, and discrete element simulation ofthis wheel models under fine particle size sand had been completed in the experimentalconditions. Experiment and simulation results show that wheel surface structures and soil properties have important influence on wheel trafficability. The plane round wheel has bettercapability to prevent subsidence, avoid slip and increase traction force than concave andconvex ones on the flowing tiny sand and dustAccording the ostrich foot morphology structure and movement mode, the self-adaptivemechanism was combined with the research results of rigid round wheel surfaces; a newbionic walking mechanism was developed. Wheel legs have effects of sand fixation and flowlimitation by cooperating with the column and the slider, and it can drive wheel thorninstitution into traction working state and non-working state to reduce the interference onsand. The multi-rigid-body dynamics analysis software was used to forecast the activity areaand interference extent among the wheel legs of the bionic walking device traveling on sand.The smoothness was selected as the index to design the optimal baseplate width of thewalking wheel. In order to verify its good traveling effectiveness on sand and its mechanismof sand fixation and flow limitation, the interaction relation between wheel foot surface andsand was analysed in discrete element method software. So the bionic walking mechanismnot only has characteristics of sand fixation and flow limitation but also could provide largertraction force, at the same time,it has good riding comfort. |
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