气动FA补偿变结构Bang-Bang位置伺服算法

 首先提出了一种基于两位两通高速开关阀的无杆气缸脉宽调制（PWM）控制方案,为气缸提供了中位截止机能。然后针对Bang-Bang控制算法中存在的超调和振荡现象,提出了摩擦力和加速度（FA）补偿的变结构Bang-Bang算法。该算法综合位置和速度误差的影响构造了加速度方向切换评价函数,考虑了摩擦力对控制量设定的影响,分别依据阶跃函数、线性函数和反正切函数对活塞加速度值进行动态设定,实现了运动过程中对活塞摩擦力的补偿和加速度的调整。最后,利用该算法进行了无杆气缸的带载伺服定位试验,对3种加速度设定函数的控制效果做了比较。结果证明FA补偿变结构算法在提高气缸定位精度方面有显著效果。

FA Compensation Variable Bang-Bang Controller for Pneumatic Position Servo

At first, this paper presents a pulse width modulation (PWM) control method for the rodless cylinder based on two-bit two-channel high speed on-off valves, which features in the ability of cutting-off the chambers of the cylinder. To overcome the phenomena of overshooting and oscillation exiting in the common Bang-Bang controller, a force and acceleration (FA) compensation variable Bang-Bang controller for PWM based pneumatic position servo is presented. Based on a trigger evaluation function whose parameters are the position error and the velocity error, the controller is able to compensate the fiction force brought out by the movement of the piston by adding the fiction force in the chamber force evaluation equation. To adjust the controlling parameters dynamically, some kinds of increasing functions, such as step function, linear function and invert tangent function, are used to setting the piston’s desired acceleration with the reduction of the position error. A pneumatic glass-wall cleaning robot "Sky-cleaner IV" is used to implement a series of on loading position servo experiments to testify the feasibility of the controllers with the above three desired acceleration setting functions respectively. The different results of them are compared to find that the FA compensation variable Bang-Bang Controller is available in promoting the position servo precision.