前轮驱动自行车机器人定车运动的建模与实现

Modeling and Realization of Track Stand Motion for a Bicycle Robot with Front-Wheel Drive

针对前轮驱动自行车机器人原地难以实现定车问题,提出一种简化的力学模型,并研究其部分反馈线性化控制策略.首先,考虑车轮纯滚动条件及定车时车把和车架垂直的特点,推导出前轮驱动角速度和车架航向角速率间的约束关系,并利用拉格朗日方程建立系统的动力学模型.然后,将系统欠驱动的车架横滚角线性化,并选择全部自由度为输出,根据部分反馈线性化原理设计定车运动控制器.仿真控制结果表明,适当地选取控制参数,系统可以在输入驱动力矩不大的情况下快速实现±10°范围内定车.物理样机实验进一步证明,利用所设计的控制器,前轮驱动自行车机器人可仅依靠前轮驱动实现小角度范围的原地定车运动.

Considering pure rolling condition and track stand motion＇s characteristics of front-bar being vertical to frame,nonholonomic constraints between front-wheel＇s driving angle velocity and frame＇s yaw angle rotational rate are derived,from which dynamic model is built by Lagrange formulation.With partial feedback linearization method,a track stand motion controller is designed,in which the under-actuated frame rolling angle is linearized and the whole dynamics are taken as output.Simulation of the controller indicates that,under proper parameters,the track stand motion within ±10° rolling angle can be achieved quickly with a small driving torque.Experiment also validates that,with the proposed controller,the front-wheel drive bicycle robot can realized a small rolling angle range of track stand motion only by front-wheel driving torque input.