| The indicator of trafficability is an important indicator of a tracked vehicle, which is the basis for applying widely in various fields. However, it has the great difficulty in the studying trafficability of tracked vehicle, due to the vast territory of our country. In order to solve the problem, based on the project background of the trafficability of crawler bulldozer, this dissertation aims to explore the unknown soil properties and predict the trafficability of tracked vehicle.In previous studies, little model is proposed for track-soil coupling system which can contain the relationship of road wheels and subsidence depth of the tracks on soft soil.Moreover, in current methods for suiting soil conditions, soil parameters need to be given and the traction performance cannot always be satisfied on soft soil. Therefore, existing methods can not solve the trafficability of track-soil coupling system when the soil properties parameters are time-variation. This paper aims to solve the above problem, and clarify the track-soil coupling mechanism. Then a detailed mathematical model is proposed which can contain the key informations of the soil and tracked vehicle. Furthermore, the evaluation system is established based on the mathematical model. Afterthat, a novel algorithm is developed for online track-soil estimation. By this method, the mathematical model and evaluation system are used to predict the trafficability for the crawler bulldozer based on the track-soil estimation on engineering.Based on the above idea, the innovative results obtained in this dissertation include:(1) Based on the analysis of track-soil coupling mechanism, the mechanism rules of track-soil coupling system are revealed. Then a mathematical model of track-soil coupling system is proposed which can contain the key informations of soil and tracked vehicle.(2) Based on the mathematical model of track-soil coupling system, the evaluation system of trafficability characteristic is established. In this evaluation system, the trafficability characteristic of tracked vehicle and soil properties can be analysised. Then the assessment index is defined, which can consider the slippage, grouser and soil properties parameters toevaluat the trafficability.(3) An improved strong tracking filtering(ISTF) algorithm is proposed, and the convergence of algorithm has been demonstrated in theory. Then a dual filter is proposed based on Kalman and ISTF. By changing the order of suboptimal fading factors, the stability of nonlinear system can be improved. ISTF and the dual filter are used to estimate the track-soil paramerters on line, whicn can solve the model uncertainty.(4) On engineering, based on the analysis of track-soil coupling mechanism, the mathematical model of track-soil coupling system is proposed for crawler bulldozer, which contain the key informatins of soil parameters and crawler bulldozer. Then the trafficability of evaluation system is established based on the track-soil estimation for crawler bulldozer.Based on the soil cone index(CI) experiments, evaluation system can analyze the impact factors on soil cone index. Finally, based on the experimental studies and soil cone index data,the evaluation system of trafficability can be corrected into practical application.This research is the challenging research which has highly practical engineering and theoretical background. The innovations of the paper are that: in theory, around track-terramechanic problem, the mathematical model of track-soil coupling system is proposed, and dual filter is used to estimate the track-soil paramerters on line, whicn can solve the problem of model uncertainty. On engineering, evaluation system of trafficability is established to enhance traction performance for the crawler bulldozer. This research has important theoretical and engineering efficiency. |
