Development of Off-road Vehicle with 4 Rotating Crawlers Driven Independently

1.我们设计和开发了一个液压动力的原型车，以克服粗糙的地形或障碍。该车辆有四套小型履带作为行走装置，履带行走的同时，履带的壳体自行转动，每个壳体的轴上连接有两套前后差速齿轮。该样机具有以下优点：1）无论地形如何起伏，四组履带都能始终保持与地形的接触; 2）只要左右两侧的地形水平相同（如：1）两组差速器都能正常工作，车辆不会发生侧倾。在沟渠或树篱上行驶），3）可以简化保持车辆底盘水平的控制系统。然而，由于左右履带之间的地面接触载荷通常是不同的，因此车辆倾向于在特定地形上引起其滚动运动。为避免滚动，四个外壳轴中至少有一个应根据地形图进行控制。讨论并设计了几种特殊的履带形状，以避免车辆的侧倾运动。通过使用这些履带，与传统的履带形状相比，左右履带的地面接触力之差可以减小到2/3-1/2左右.设计并研制了一种装有四套轮胎行走装置的模型车，其壳体轴由两个直线轴承构成，使左右壳体轴所受力矩保持一致。该装置的两个壳体轴连接到一组差动齿轮，并且轮胎的地面接触力变得相等，因为壳体轴处的力矩相同。具有各种地形形状的台架测试显示出期望的性能，尽管至少一个壳体应如上所述进行控制。

1. We designed and developed a hydrawlic powered prototype vehicle to overcome rough terrains or obstacles. The vehicle has four sets of small type crawler as running device, whose housing rotates by itself at the same time the crawler moves for running, and each housing shafts are connected to two sets of front and rear differential gear. The prototype showed many benefits such as : 1)the whole four sets of crawler can always stay in touch with terrain regardless of its bumpy figure, 2) the two sets of differential gear can work normally without having rolling motion of the vehicle as long as the level of the terrain is the same between right and left side (eg. overriding on the ditch or hedge), 3) the control system to keep maintaining the vehicle chassis horizontal can be simplified. However, the vehicle tend to induce its rolling motion on certain figure of the terrain because the ground contact loads between the right and left crawlers, in general, are different. To avoid rolling, at least one housing shaft out of four should be controlled in accordance with figure of the terrain.2. Some particular crawler's shapes were discussed and designed to avoid the rolling motion of vehicle. By using these crawlers, the difference of the ground contact forces between the right and left crawlers can be decreased to about 2/3-1/2 compared with the traditional shape of crawler.3. We designed and developed a model vehicle equipped with four sets of running device with a tire, whose housing shaft was constituted with two linear bearings so that the moment exerted to the right and left housing shafts stayd the same. Two housing shafts of the device were connected to a set of differential gears, and the ground contact forces of the tires became equal, being the fact that the moments at the housing shafts were the same. A bench test with various terrain shape showed desired performance, although at least one of the housing should be controlled as above.