axebot机器人：全方位自主移动机器人的机械设计毕业论文外文翻译(编辑修改稿)

axebot机器人：全方位自主移动机器人的机械设计毕业论文外文翻译(编辑修改稿)内容摘要：

2020 first had Delrin rollers to minimize friction and weight. Delrin is a kind of plastic which is used with moving contact surfaces because of its low friction coefficients with other materials. After a few test with the prototype robot it became clear that the Delrinrollers easily broke with a collision. Therefore the Cornell Robot 2020 was equipped with aluminum rollers. These were strong enough to withstand collisions and aluminum has a low density (pared to other metals). However, during other prototype tests of the Cornell Robot 2020 team some aluminum residue built up on the steel rollers axles. The Cornell Robot 2020 did not encounter problems due to the wearing of the aluminum rollers, but to optimize the design of the AxeBot wheels this problem was solved. To avoid wearing of the aluminum rollers other material for the axles can be used or the rollers can be made of a tougher material. After a few calculations it became clear that roller axles of Delrin (to reduce the friction) are strong enough (see the section about the axles), but it is not possible to produce thin bars of Delrin. Therefore steel axles are used, the same material as the roller axles of the Cornell Robot 2020. So to avoid wear of the rollers a more though material than aluminum has to be used for the rollers. Steel is more though and an easily obtainable and cheap material. A disadvantage of steel pared to aluminum is its higher density. This will increase the moment of the inertia which „costs‟ more torque of the motor. The total moment of inertia of a wheel with steel rollers is 10−4kgm2 and the moment of inertia of a wheel with aluminum rollers is 10−4kgm2. Using steel rollers instead of aluminum rollers would increase the moment of inertia by 7 this increase is neglectable small and steel rollers can be used. Concerning friction, using steel rollers and steel axles is also better than using aluminum rollers and steel axles since the frictioncoefficient between steel and steel is lower than that between steel and aluminum. A lubricant can also be used to even more reduce friction. . Roller axle As mentioned above, the use of Delrin for the roller axles was investigated since it would reduce the wear of the aluminum rollers. In a static situation was calculated whether Delrin axles of mm diameter would be strong enough. This was also done in a dynamical situation (dropping the robot on the floor and landing on one roller), but without using a Finite Element Method this did not result in realistic results. When the total weight of kg of one AxeBot 2020 would pletely be on one roller axle this would result in a shear stress in the axle. In this situation the shear stress can be calculated by dividing the force on the axle (due to the weight of the AxeBot) by the area of the shear plane. The area of the shear plane is of course the area of a circle with a radius similar to the radius of the axles. Note that the weight of the AxeBot has to be divided by two since there are two shear planes in one axle. The magnitude of the shear stress would be MPa. Delrin starts to plastically deform in due to shear at around 44 MPa. Statically, Delrin axles would be strong enough. However, this calculation was not necessary it became clear that it is not possible to produce Delrin bars of mm (diameter). Therefore steel axles will be used (aluminum axles would result in more friction). To reduce friction, the axles were coated with a lubricant like carbon. Lubricants like carbon are easily available. The Cornell robot team 2020 documentation does not mention problems of wear of their polycarbonate shells due to their steel roller axles. As one can be read further down this section, the shells of the AxeBot wheels will be made of aluminum or polycarbonate. The coefficient of friction between aluminum (shells) and steel (axles) and between polycarbonate (shells) and steel (axles) are of equal sizes (about []). Also, the geometry of the wheels of the Cornell robot and the AxeBot are almost the same. Therefore it is most likely that wearing due to friction will not be a problem with steel roller axles and polycarbonate or aluminum shells. Production the axles can easily be made out of a steel bar. Depending on the available diameters of steel bars, the diameter of the axles could be adjusted. The edges of the axles are rounded to avoid sharp corners. . Hub The hub connects the wheel to the axle of the motor. A M2bolt can be used for this purpose, the hole in the hub where this bolt will be placed is dimensioned mm in diameter so screw thread can be made to fit in the M2bolt. The hub is connected to the shells by three M3screws. Corresponding holes of mm will be made in the hub and the shells. The geometry of the hub can be changed to facilitate the production process. The hub can be made out of aluminum or polycarbonate, both light materials. To investigate the option (and price) of injection moulding the hub out of polycarbonate a sketch of a design for a mould has been made. . Shells Almost the all geometry of the shells of the Cornell Robot 2020 is used. Only little changes in the slots for the rollers of the axles have been made to facilitate the production process of the shells. In the section about the production of the shells a different design for the slots of the axles is presented to make the production of the shells easily. The shells can be made out of aluminum or a though, light plastic like polycarbonate. The Cornell Robot had shells of polycarbonate. The best machinable material is preferred, and the one used on the AxeBot‟s shell. When using a plastic that can be injection molded, molds have been designed to check the prices of injection moulding. 4. Shooting Device This design consists of a vertical arm (the kick arm), that ca。