Self-lock characteristics of the continuous alternate wheel and the mobile robot are described. The structure of the continuous alternate wheel is analyzed firstly. The friction of a locked wheel can be divided into sliding friction in radial direction as well as rolling friction and bearing friction in axial direction, which are measured by experiment. Then, self-lock characteristics of the continuous alternate wheel are introduced based on the frictions measured above. The self-lock areas of the wheel on paper and on carpet are 0~ 15° and 0~ 18° by experiments. At last, a mathematical force model of a self-locked robot on a slope is developed, and some experiments about the robot self-lock characteristics on the slope of different materials, i.e. paper and carpet, are carried out. The experiment results indicate that the smallest self-lock angles of the robot on paper and on carpet are 19.7° and 16.4° respectively when the angle between the robot coordinate and slope coordinate is 45°. Meanwhile, the biggest self-lock angles of the robot on paper and on carpet are 30.3° and 25.5° respectively when the angle between the robot coordinate and slope coordinate is 0.
[1] 王卫华,熊有伦,孙荣磊.一种移动机器人轮子打滑的实验校核方法[J].机器人,2005,27(3):197-202. Wang W H, Xiong Y L, Sun R L. An experimental calibration method for wheel-slippage in mobile robots[J]. Robot, 2005, 27(3): 197-202.[2] Mori Y, Nakano E, Takahashi T, et al. Mechanism and running modes of new omni-directional vehicle ODV9[J]. JSME International Journal: Series C, 1999, 42(1): 210-217. [3] Nagatani K, Tachibana S, Sofue M, et al. Improvement of odometry for omnidirectional vehicle using optical flow information[C]//IEEE/RSJ International Conference on Intelligent Robots and Systems. Piscataway, USA: IEEE, 2000: 468-473.[4] Gracia L, Tornero J. Kinematic modeling of wheeled mobile robots with slip[J]. Advanced Robotics, 2007, 21(11): 1253-1279. [5] Williams II R L, Carter B E, Gallina P, et al. Dynamic model with slip for wheeled omnidirectional robots[J]. IEEE Transactions on Robotics and Automation, 2002, 18(3): 285-293. [6] 黄善均,林光.一种新型的万向车轮:中国,1435330[P]. 2003-08-13. Huang S J, Lin G. A new type omnidirectional wheel: China, 1435330[P]. 2003-08-13.[7] 漆安慎,杜婵英.力学[M].北京:高等教育出版社,1996. Qi A S, Du C Y. Mechanics[M]. Beijing: Higher Education Press, 1996.[8] 瓦伦丁 L P.接触力学与摩擦学的原理及其应用[M].李强,雒建斌,译.北京:清华大学出版社,2008. Valentin L. Contact mechanics and friction physical principles and applications[M]. Li Q, Luo J B, trans. Beijing: Tsinghua University Press, 2008.[9] Hwang Y S, Lee J, Hsia T C. A recursive dimension-growing method for computing robotic manipulability polytope[C]//IEEE International Conference on Robotic and Automation. Piscataway, USA: IEEE, 2000: 2569-2574.