无机械调节器的自行车机器人圆周运动实现

Circular Motion Realization of a Mechanical Regulator Free Bicycle Robot

为了研究无机械调节器自行车机器人的曲线运动平衡能力,给出一种前轮驱动自行车机器人的欠驱动力学模型以及这种机器人在水平面上实现小半径圆周运动的方法。根据几何关系得到车体的转弯半径,以此为基础推导出后轮转角速度和车架航向角速率,进一步采用拉格朗日方程建立系统的力学模型;分析圆周运动下重力矩和向心力矩的动态平衡条件,得到前轮驱动速度、车架横滚角以及车把转角之间的量化关系;基于部分反馈线性化方法,将模型中的欠驱动子系统线性化,设计出圆周运动控制器,并通过动态平衡条件设定车架横滚角和前轮驱动速度期望值来加速算法收敛。仿真控制和样机试验结果表明,控制器可以提供合理的驱动力矩实现自行车机器人的圆周平衡行走,并且给定不同的车架横滚角期望值可以对应得到不同的圆周运动周期,期望值越大,圆周运动周期越短。

In order to deal with balanced control of curvilinear motion for bicycle robot without mechanical regulator, a front-wheel drive bicycle robot is taken into consideration, including its simplified under-actuated dynamics and physical realization for circular motion. According to geometrical relationship, turning radius of the robot is get, and yaw rate of flame together with rotational velocity of rear-wheel are derived. Based on Lagrange formulation, dynamics of the system is established. Considering dynamic balance between gravitational moment and centripetal force moment under circular motion, the mathematical relationship among front-wheel driving velocity, frame roUing angle and front-bar rotational angle is derived. By linearizing the under-actuated firne rolling angle, balanced controller for circular motion is constructed with partial feedback linearization, in which dynamic balance condition is used to set expected values of frame rolling angle and front-wheel driving velocity for accelerating algorithm convergence. Simulation and prototype experiment results show that the proposed controller can realize circular motion with reasonable driving torque, and the expected value of the different rolling angle can lead to different circular motion period, which can be described as the bigger of the expected value is, the smaller of the motion period will be.