汽车电泳涂装输送用混联机构的分数阶PI~λD^u控制

Fractional-Order PI~λD^u Control of Hybrid Mechanism for Automobile Electro-Coating Conveying

针对一种新型汽车电泳涂装输送用混联机构,基于机构结构特点,分别采用单回路控制策略对混联机构的各条支路进行独立控制。由于机构在实际的运动过程中,各支路间存在耦合关系,会引起系统的不稳定。因此,为了解决输送机构各支路间耦合作用,提高控制系统在高速度、高加速度的情况的控制精度,提出了一种分数阶+前馈补偿控制策略对输送机构的各支路进行独立控制,并通过建立动力学模型和定义的耦合强度系数,进一步分析得出各支路之间存在耦合作用,采用前馈补偿的方式消除耦合作用的影响。然后,利用遗传算法对所提出的分数阶控制器进行参数优化。最后利用MATLAB软件分别对分数阶控制+前馈补偿和经典PID控制+前馈补偿进行仿真比较,结果表明分数阶控制+前馈补偿控制有着良好的跟踪性能,对外部的随机干扰具有较好的鲁棒性,且系统稳态误差较小,满足系统高性能控制要求。

Based on the structural characteristics of a novel hybrid mechanism for automobile electro-coating conveying, the single-loop control strategy is adopted to control each branch of the hybrid mechanism independently. During the process of actual movement, there are coupling relationships among every branches, which will affect the dynamic and static characteristics of the system, and even lead to the system instability. Therefore, in order to eliminate the coupling effects among the branches of the conveying mechanism and improve the control precision of the control system in case of high speed and high acceleration, a fractional-order combined with feed-forward compensation control strategy is proposed to control each branch of the conveying mechanism independently. At the same time, further analysis of coupling effects among branches are obtained by establishing dynamic model and defining the coupling strength coefficient, then the coupling effect is eliminated by feed-forward compensation. After that, the genetic algorithm is used to optimize the parameters of the proposed fractional-order controller. Finally, the MATLAB simulation results demonstrate that the fractional-order control combined with feed-forward compensation has better tracking performance, stronger robustness for random disturbance and smaller steady-state error comparing with the classical PID control combined with feed-forward compensation. To sum up, the proposed control method could satisfy the requirements of high-performance control of the system.