CT扫描攀爬机器人模糊PID力控制算法

Fuzzy PID Force Control Algorithm for the CT Scaning Climbing Robot

【目的】提出一种CT扫描攀爬机器人水平伸缩关节夹持力模糊PID控制算法,以实现其夹持力的精确控制,增强对古建筑立木柱的安全保护。【方法】首先,使用巴特沃斯二阶低通滤波器对压力传感器输出值进行滤波,减弱噪声等干扰信号对测量值的影响;然后,以力误差和力误差变化率为系统输入,选择三角函数为隶属度函数进行模糊化处理,根据PID整理规则分别建立PID参数的模糊推理规则,利用系数加权平均法对系统输出进行反模糊化处理;最后,对比分析模糊PID控制算法和耦合PD控制算法的力控制效果。【结果】接触过程中,压力传感器信号经滤波处理后,波动明显减小。夹紧过程中,相比耦合PD控制算法,模糊PID控制算法的夹持力控制精度最大可提高51.8%,相对关节力误差最高可提高99.8%,力调节时间也不同程度优化,且模糊PID控制算法还可消除夹持力调节过程中的超调现象。【结论】巴特沃斯二阶低通滤波可有效滤除压力传感器输出值中噪声等信号的干扰,提高接触检测的可靠性;相比耦合PD控制算法,模糊PID控制算法具有更好的夹持力控制效果,不仅可以提高CT扫描攀爬机器人工作的可靠性,而且能够进一步保证古建筑木立柱的安全。

【Objective】 In order to achieve precise control of clamping force, a fuzzy PID control algorithm is proposed for horizontal translational joints of the climbing robot.【Method】 Firstly, a Butterworth two-order low pass filter is designed to filter the output of the force sensor for weakening the influence of the interference on the force sensor. Then, the error and the variation rate of force are input to the system, and fuzzification is done by choosing the trigonometric function as the membership function. Followly, the fuzzy inference rules of PID are established according to the PID rules, and defuzzication of output is achieved using coefficient weighted average method . Finally, the effect of the force control test of the fuzzy PID algorithm and the PID coupling algorithm is analyzed comparatively.【Result】 In the contact, the fluctuation of force is weakened obviously by the filter. In the clamping, comparing to the coupling PD algorithm, the maximum precision is increased by 51.8%, the maximum force error between the relative joints is improved by 99.8%, and the time of dynamic adjustment is also optimized in different degrees. In addition, the overshoot of the clamping force is eliminated as well.【Conclusion】 The filter can effectively filter the interference in the signals of the force sensors, and improve the reliability of the contact detection. The effectiveness of fuzzy PID clamping force control algorithm is also verified better than that of the coupling PD clamping force control algorithm, which can not only improve the reliability of the climbing robot, but also guarantee the safety of the wooden column.