基于分数阶控制器的电液伺服系统位置控制的研究

Research on Position Control of Electro-hydraulic Servo System Based on Fractional Controller

为了适应电液伺服系统的非线性特征,提高它对期望位置跟踪的准确性,提出基于分数阶控制器的电液伺服系统位置控制方法。在对电液伺服系统进行建模的基础上,分析其工作过程,并得出伺服阀内流量的连续方程以及活塞的运动方程,建立了电液伺服系统中伺服阀的一阶模型。通过分析PID控制器,构建了鲁棒性能较好的分数阶控制器,加入了调节参数,以更好地调节控制系统的动态特性。采用遗传算法对分数阶控制器的相关参数进行调整,使其能够更好地适应电液伺服系统的非线性特征,从而控制电液伺服系统准确地对期望位置进行跟踪。实验中利用设计的分数阶控制器对阶跃以及正弦期望位置轨迹进行跟踪,以测试其控制性能。从测试结果可见:相对于粒子群控制器,采用分数阶控制器跟踪阶跃和正弦期望位置轨迹时,产生的最大超调率分别减少了7.56%和8.75%,说明设计的分数阶控制器能够较好地控制电液伺服系统对期望位置轨迹进行跟踪。

In order to adapt to the non-linear characteristics of the electro-hydraulic servo system and improve its tracking accuracy to desired position,a position control method for the electro-hydraulic servo system based on fractional order controller was proposed.Based on the modeling of the electro-hydraulic servo system,the working process was analyzed,and the continuous equation of the flow in the servo valve and the motion equation of the piston were obtained.The first-order model of the servo valve in the electro-hydraulic servo system was established.Through the analysis to the PID controller,a fractional order controller with better robustness was constructed,and adjusting parameters were added to make the dynamic characteristics of the system be better regulated and controlled.Genetic algorithm was used to adjust the parameters of the fractional order controller,so it could better adapt to the non-linear characteristics of the electro-hydraulic servo system,so as to control the electro-hydraulic servo system to track the desired position accurately.The designed fractional order controller was used to track the step and sinusoidal desired position trajectory in order to test its control performance.The test results show that the maximum overshoot rate of fractional order controller is reduced by 7.56%and 8.75%respectively when tracking step and sinusoidal desired position trajectories compared with particle swarm optimization controller.It shows that the designed fractional order controller can be used to control the electro-hydraulic servo system to track the desired position trajectory better.