2自由度门式起重机器人的轨迹控制

Trajectory Control a 2-Degree-of-freedom Gantry Crane Robot

为了解决2自由度门式起重机器人系统的吊运轨迹精确跟踪控制和反晃动的有效消除,在建立其非线性动力学模型的基础上,详细分析其所呈现的微分平坦性,指出这种微分平坦性对精确轨迹的生成带来了很大的便利;接着分析了其前馈控制器和基于微分平坦性的反馈轨迹跟踪控制器,指出其具有微分平坦性的动力学系统是非线性的,故其所对应的状态方程是非线性的,但可通过状态变换实现无反馈精确线性化,从而得到一个完全能观完全能控的线性系统;若对该线性系统施加一个误差线性反馈器,就得到输出解耦的闭环系统,这样通过调整反馈增益可使吊具的轨迹误差实现全局渐近收敛;仿真结果验证了理论研究结论的正确性,同时表明吊具在低速运动时,摩擦对起重机器人系统的驱动力输入的影响不大。

In order to realize the accurate trajectory tracking and anti-swing control of 2 degree-of-freedom gantry crane robot, detailed analysis of the differential flatness on the basis of its nonlinear dynamic model is given and it is pointed out that such kind of differential flatness is beneficial to accurate trajectory generation. The feedforward controller and feedback trajectory tracking controller are analyzed and it is found that the corresponding state space is nonlinear because the flatness-based dynamic system is nonlinear, but through the state space transformction, the system can be changed into a system of exact linearization without feedback. Hemee them a totally being observed and controled linear system is obtained. If an elTor linear feedback controller can be odded to this linear system, Thus, the error between the desired and real trajectory of the spreader can realize global asymptotic stability and convergence by adjusting the feedback gains. The simulation resuhs has proven the correctness of the theoretical conclusions and shown that influence of the friction on the inputs for the actuators is little when the spreader moves with a low speed.